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Search for "cyclophane" in Full Text gives 33 result(s) in Beilstein Journal of Organic Chemistry.
Switchable molecular tweezers: design and applications
- Pablo Msellem,
- Maksym Dekthiarenko,
- Nihal Hadj Seyd and
- Guillaume Vives
Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45
- solution. This concept was further developed with a bis-acridinium cyclophane [31] as a multiresponsive receptor for selective phase transfer. In organic media, this macrocyclic receptor presented an affinity for polyaromatic guests with strong selectivity for perylene. A reversible guest release was
Graphical Abstract
Figure 1: Principle of switchable molecular tweezers.
Figure 2: Principle of pH-switchable molecular tweezers 1 [19].
Figure 3: a) pH-Switchable tweezers 2 substituted with alkyl chains as switchable lipids. b) Schematic depict...
Figure 4: Modification of spectral properties of 3 by controlled induction of Pt–Pt interactions.
Figure 5: Conformational switching of di(hydroxyphenyl)pyrimidine-based tweezer 4 upon alkylation or fluoride...
Figure 6: Hydrazone-based pH-responsive tweezers 5 for mesogenic modulation.
Figure 7: pH-Switchable molecular tweezers 6 bearing acridinium moieties.
Figure 8: a) Terpyridine and pyridine-hydrazone-pyridine analogs molecular tweezers and b) extended pyridine ...
Figure 9: Terpyridine-based molecular tweezers with M–salphen arms and their field of application. Figure 9 was adapt...
Figure 10: a) Terpyridine-based molecular tweezers for diphosphate recognition [48]; b) bishelicene chiroptical te...
Figure 11: Terpyridine-based molecular tweezers with allosteric cooperative binding.
Figure 12: Terpyridine-based molecular tweezers presenting closed by default conformation.
Figure 13: Pyridine-pyrimidine-pyridine-based molecular tweezers.
Figure 14: Coordination-responsive molecular tweezers based on nitrogen-containing ligands.
Figure 15: Molecular tweezers exploiting the remote bipyridine or pyridine binding to trigger the conformation...
Figure 16: Bipyridine-based molecular tweezers exploiting the direct s-trans to s-cis-switching for a) anion b...
Figure 17: a) Podand-based molecular tweezers [66,67]. b) Application of tweezers 32 for the catalytic allosteric reg...
Figure 18: Anion-triggered molecular tweezers based on calix[4]pyrrole.
Figure 19: Anion-triggered molecular tweezers.
Figure 20: a) Principle of the weak link approach (WLA) developed by Mirkin and its application to b) symmetri...
Figure 21: Molecular tweezers as allosteric catalyst in asymmetric epoxide opening [80].
Figure 22: Allosteric regulation of catalytic activity in ring-opening polymerization with double tweezers 41.
Figure 23: a) Conformational switching of 42 by intramolecular –S–S– bridge formation. b) Shift of conformatio...
Figure 24: a) Redox-active glycoluril-TTF tweezers 44. b) Mechanism of stepwise oxidation of said tweezers wit...
Figure 25: Mechanism of formation of the mixed-valence dimers of tweezers 45.
Figure 26: Mechanism of carbohydrate liberation upon redox-mediated conformation switching of 46.
Figure 27: a) The encapsulation properties of 47 as well as the DCTNF release process from its host–guest comp...
Figure 28: Redox-active bipyridinium-based tweezers. a) With a ferrocenyl hinge 49, b) with a propyl hinge 50 ...
Figure 29: Redox-active calix[4]arene porphyrin molecular tweezers.
Figure 30: a) Mechanism of the three orthogonal stimuli. b) Cubic scheme showing the eight different states of ...
Figure 31: Redox-controlled molecular gripper based on a diquinone resorcin[4]arene.
Figure 32: a) Shinkai's butterfly tweezers and their different host–guest properties depending on the isomer. ...
Figure 33: Cyclam-tethered tweezers and their different host–guest complexes depending on their configuration.
Figure 34: Azobenzene-based catalytic tweezers.
Figure 35: Photoswitchable PIEZO channel mimic.
Figure 36: Stilbene-based porphyrin tweezers for fullerene recognition.
Figure 37: Stiff-stilbene-based tweezers with urea or thiourea functional units for a) anion binding, b) anion...
Figure 38: Feringa’s photoswitchable organocatalyst (a) and different catalyzed reactions with that system (b)....
Figure 39: a) Irie and Takeshita’s thioindigo-based molecular tweezers. b) Family of hemithioindigo-based mole...
Figure 40: Dithienylethylene crown ether-bearing molecular tweezers reported by Irie and co-workers.
BINOL as a chiral element in mechanically interlocked molecules
- Matthias Krajnc and
- Jochen Niemeyer
Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53
- spectroscopic analysis of the [2]catenanes (18, 20, and 22) revealed various dynamic processes in solution. While circumrotation of the polyether macrocycle around the tetracationic cyclophane was either impossible (for 18 and 20, due to the presence of the sterically demanding BINOL unit) or slow on the NMR
- timescale at room temperature (for 22), the other two dynamic processes, namely circumrotation of the tetracationic cyclophane through the cavity of the polyether and a “rocking motion” of the oxygen–oxygen axis of the hydroquinone units, were fast on the NMR timescale at room temperature. In a follow-up
- and P isomers), similar to (S,S)-5 (see Figure 2). Secondly, the embedding of the DNP unit in the tetracationic cyclophane leads to an element of planar chirality (Rp and Sp isomers). Thus, for each configuration of BINOL, four different diastereoisomers are possible. However, for these specific
Graphical Abstract
Figure 1: Molecular structures of (R)-BINOL (left) and (S)-BINOL (right).
Figure 2: Synthesis of Sauvage´s [2]catenanes (S,S)-5 and (S,S)-6 containing two BINOL units by the passive m...
Figure 3: Synthesis of Saito´s [2]rotaxane (R)-10 from a BINOL-based macrocycle by the active metal template ...
Figure 4: Synthesis of Stoddart´s [2]rotaxane (rac)-14 by an ammonium crown ether template.
Figure 5: Synthesis of Stoddart´s BINOL-containing [2]catenanes 18/20/22/24 by π–π recognition.
Figure 6: Synthesis of Takata´s rotaxanes featuring chiral centers on the axle: a) rotaxane (R,R,R/S)-27 obta...
Figure 7: Takata´s chiral polyacetylenes 32/33 featuring BINOL-based [2]rotaxane side chains.
Figure 8: Synthesis of Takata´s chiral thiazolium [2]rotaxanes (R)-35a/b and (R)-38.
Figure 9: Results for the asymmetric benzoin condensation of benzaldehyde (39) with catalysts (R)-35a/b and (R...
Figure 10: Synthesis of Takata´s pyridine-based [2]rotaxane (R)-42.
Figure 11: The asymmetric desymmetrization reaction of meso-1,2-diols with rotaxane (R)-42.
Figure 12: Synthesis of Niemeyer´s axially chiral [2]catenane (S,S)-47.
Figure 13: Results for the enantioselective transfer hydrogenation of 2-phenylquinoline with catalysts (S,S)-47...
Figure 14: Synthesis of Niemeyer´s chiral [2]rotaxanes (S)-56/57.
Figure 15: Results for the enantioselective Michael addition with different rotaxane catalysts (S)-56a/56b/57a/...
Figure 16: Synthesis of Beer´s [2]rotaxanes 64a/b for anion recognition.
Figure 17: Association constants of different anions (used as the Bu4N+ salts) to the [2]rotaxanes (S)-64a/b a...
Figure 18: Synthesis of Beer´s [3]rotaxane (S)-68.
Figure 19: Association constants of different anions (used as the Bu4N+-salts) to the [2]rotaxane (S)-68 and a...
Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro[2.2]metaparacyclophanes
- Suraj Patel,
- Tyson N. Dais,
- Paul G. Plieger and
- Gareth J. Rowlands
Beilstein J. Org. Chem. 2021, 17, 1518–1526, doi:10.3762/bjoc.17.109
- ]metaparacyclophane and a cyclohexadienone cyclophane. Keywords: cyclophane; metaparacyclophane; nitration; paracyclophane; rearrangement; Introduction Cyclophanes have been described as having bent and battered benzene rings [1] due to a structure that involves one, or more, aromatic rings linked by aliphatic
- chains at non-adjacent carbon positions. Their constrained three-dimensional shapes enforce unusual conformations and interactions between the aromatic decks, all of which results in their unique properties [2][3][4][5]. The most studied cyclophane is [2.2]paracyclophane (1, Figure 1). Not only is it the
- archetypal cyclophane, with a strong interaction between the two aromatic rings, but it is readily available, being a ‘dimer’ for the polymer parylene [6][7]. Over the last twenty years, there has been a resurgence in interest in this compound as a scaffold for the synthesis of asymmetric catalysts, energy
Graphical Abstract
Figure 1: The common [2.2]cyclophanes.
Scheme 1: Nitration of [2.2]paracyclophane (1) and the synthesis of 4-hydroxy-5-nitro[2.2]metaparacyclophane (...
Figure 2: Crystal structure of 5. Ellipsoids are drawn at a 50% probability level [63-66].
Figure 3: Crystal structure of 6. Ellipsoids are drawn at a 50% probability level [63].
Scheme 2: Possible mechanism for the formation of [2.2]metaparacyclophane 5 and cyclohexadienone cyclophane 6...
Scheme 3: Conjugate addition of methanol and subsequent elimination.
Figure 4: Crystal structure of 14. Ellipsoids are drawn at a 50% probability level [63].
Figure 5: Crystal structure of 15. Ellipsoids are drawn at a 50% probability level [63].
Figure 6: Possible origin of stereoselectivity.
Chiral isothiourea-catalyzed kinetic resolution of 4-hydroxy[2.2]paracyclophane
- David Weinzierl and
- Mario Waser
Beilstein J. Org. Chem. 2021, 17, 800–804, doi:10.3762/bjoc.17.68
- decades, it was shown that enantioenriched 2 may serve as a valuable building block to access more advanced chiral cyclophane ligands and catalysts [3][4][19][20][21][22] and therefore its asymmetric synthesis became an important task [3][4][18][19][20][21][22][23][24][25][26][27]. Several strategies to
Graphical Abstract
Scheme 1: Overview about established methods to access enantioenriched 2 and the herein investigated kinetic ...
Scheme 2: Use of alternative acylating agents 4 for the kinetic resolution of rac-2.
1,2,3-Triazolium macrocycles in supramolecular chemistry
- Mastaneh Safarnejad Shad,
- Pulikkal Veettil Santhini and
- Wim Dehaen
Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211
- fundamental hydrogen bonding and electrostatic interactions related to the individual recognition motifs [53]. Another cyclophane macrocycle containing two 1,2,3-triazolium moieties was synthesized by Alcalde and co-workers in a moderate yield [54]. The anion-binding behavior of receptor 11 (Figure 10) was
- helped to increase the ability of complexation of 12 with iodide [56]. 2.7. Functional molecular crystal and materials Combining anion–arene interactions and controlling the electron-transfer or charge-transfer process concerning an anionic guest by using a cyclophane is uncommon [57] but can be realized
- by inserting a photoactive binding motif into a cyclophane [58]. In this regard, Li et al. have synthesized a cationic cyclophane 13 (Figure 11) based on an electron poor naphthalenediimide (NDI) moiety and cationic 1,2,3-triazolium units. Cyclophane 13 was employed to control the interactions
Graphical Abstract
Figure 1: Hydrogen, halogen or chalcogen bonding to anions within a bistriazolium macrocycle.
Figure 2: Main synthetic strategies towards macrocyclic triazoliums.
Figure 3: Chemical structure of compound 1 (1a, 1b and 1c) and 2.
Figure 4: Chemical structure of compound 3 and 4.
Figure 5: Chemical structure of compound 5.
Figure 6: Chemical structure of compound 6.
Figure 7: Chemical structure of compound 7.
Figure 8: Chemical structure of compound 8.
Figure 9: Chemical structures of compound 9.
Figure 10: Chemical structures of compound 10, 11 and 12.
Figure 11: Chemical structure of compound 13.
Figure 12: Chemical structure of compound 15 including the sigma-connected TCNQ dimer.
Figure 13: Chemical structure of compound 16 for the kinetic resolution of epoxides.
Figure 14: Chemical structure of compound 17a (bisnaphtho crown ether shown).
Figure 15: Jump rope in molecular double-lasso compounds 18.
Figure 16: Chemical structure of compound 19 and acid–base triggered motions.
Learning from B12 enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis
- Keishiro Tahara,
- Ling Pan,
- Toshikazu Ono and
- Yoshio Hisaeda
Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232
- cyclophane-type B12 artificial enzyme also mediated similar carbon-skeleton rearrangements [32]. We developed another artificial enzyme composed of human serum albumin (HSA) and heptapropyl cobyrinate [34]. It is known that HSA acts as a carrier for in vivo hydrophobic molecules. Hydrophobic B12 model
Graphical Abstract
Figure 1: (a) Structure and (b) reactivity of B12.
Figure 2: (a) Schematic representation of B12 enzyme-involving systems. (b) Construction of biomimetic and bi...
Scheme 1: (a) Carbon-skeleton rearrangement mediated by a coenzyme B12-depenedent enzyme. (b) Electrochemical...
Scheme 2: Electrochemical carbon-skeleton arrangements mediated by B12 model complexes.
Figure 3: Key electrochemical reactivity of 1 and 2 in methylated forms.
Scheme 3: Carbon-skeleton arrangements mediated by B12-vesicle artificial enzymes.
Scheme 4: Carbon-skeleton arrangements mediated by B12-HSA artificial enzymes.
Scheme 5: Photochemical carbon-skeleton arrangements mediated by B12-Ru@MOF.
Scheme 6: (a) Methyl transfer reaction mediated by B12-dependent methionine synthase. (b) Methyl transfer rea...
Scheme 7: Methyl transfer reaction for the detoxification of inorganic arsenics.
Scheme 8: (a) Dechlorination of 1,1,2,2-tetrarchloroethene mediated by a reductive dehalogenase. (b) Electroc...
Scheme 9: Visible-light-driven dechlorination of DDT using 1 in the presence of photosensitizers.
Scheme 10: 1,2-Migration of a phenyl group mediated by the visible-light-driven catalytic system composed of 1...
Scheme 11: Ring-expansion reactions mediated by the B12-TiO2 hybrid catalyst with UV-light irradiation.
Scheme 12: Trifluoromethylation and perfluoroalkylation of aromatic compounds achieved through electrolysis wi...
Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps
- Sambasivarao Kotha,
- Milind Meshram and
- Chandravathi Chakkapalli
Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223
- %). Subsequently, hydrogenation of compounds 126 and 125 was accomplished with H2 under Pd/C catalysis conditions to afford the respective saturated macrocyclic products 127 (80%) and 128 (90%). Since the small ring cyclophane is highly strained, compound 125 was formed as a minor product (Scheme 19). Recently, Li
- coupling approach to Z-stilbene derivative 85. Synthesis of substituted trans-stilbene derivatives via SM coupling and RCM. Synthesis of biaryl derivatives via sequential EM, DA followed by SM coupling. Synthesis of the dibenzocyclooctadiene core of schisandrene. Synthesis of cyclophane 115 via SM coupling
- and RCM as key steps. Synthesis of cyclophane 120 and 122 via SM coupling and RCM as key steps. Synthesis of cyclophanes via SM and RCM. Synthesis of MK-6325 (141) via RCM and SM coupling. Acknowledgements We thank the Council of Scientific and Industrial Research (CSIR), New Delhi [02(0272)/16/EMR
Graphical Abstract
Figure 1: Various catalysts used for metathesis reactions.
Scheme 1: SM coupling and RCM protocol to substituted indene derivative 10.
Scheme 2: Synthesis of polycycles via SM and RCM approach.
Figure 2: Various angucyclines.
Scheme 3: SM coupling and RCM protocol to the benz[a]anthracene skeleton 26.
Scheme 4: Synthesis of substituted spirocycles via RCM and SM sequence.
Scheme 5: Synthesis of highly functionalized bis-spirocyclic derivative 37.
Scheme 6: Synthesis of spirofluorene derivatives via RCM and SM coupling sequence.
Scheme 7: Synthesis of truxene derivatives via RCM and SM coupling.
Scheme 8: Synthesis of substituted isoquinoline derivative via SM and RCM protocol.
Scheme 9: Synthesis to 8-aryl substituted coumarin 64 via RCM and SM sequence.
Scheme 10: Synthesis of cyclic sulfoximine 70 via SM and RCM as key steps.
Scheme 11: Synthesis of 1-benzazepine derivative 75 via SM and RCM as key steps.
Scheme 12: Synthesis of naphthoxepine derivative 79 via RCM followed by SM coupling.
Scheme 13: Sequential CM and SM coupling approach to Z-stilbene derivative 85.
Scheme 14: Synthesis of substituted trans-stilbene derivatives via SM coupling and RCM.
Scheme 15: Synthesis of biaryl derivatives via sequential EM, DA followed by SM coupling.
Scheme 16: Synthesis of the dibenzocyclooctadiene core of schisandrene.
Scheme 17: Synthesis of cyclophane 115 via SM coupling and RCM as key steps.
Scheme 18: Synthesis of cyclophane 120 and 122 via SM coupling and RCM as key steps.
Scheme 19: Synthesis of cyclophanes via SM and RCM.
Scheme 20: Synthesis of MK-6325 (141) via RCM and SM coupling.
Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules
- Hendrik V. Schröder and
- Christoph A. Schalley
Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190
- first TTF-based pseudorotaxane was reported by Stoddart and Williams in 1991 (Figure 5) [33]. At this time, they investigated the host–guest properties of the π-electron-poor cyclophane cyclobis(paraquat-p-phenylene) (3) in form of the tetrakis(hexafluorophosphate) salt [58]. The square-shaped host
- -called “rotacatenane” (Figure 22) [99]. The rotacatenane 24 consists of their previously used rotaxane framework except that the enlarged cyclophane cyclobis(paraquat-4,4′-biphenylene) is used as wheel component. The cavity of this macrocycle is large enough to host two planar molecules in a cofacial
- breakthroughs for the construction of TTF-based supramolecular architectures: (b) Stepwise deprotection/alkylation, (c) phosphite-mediated heterocoupling, and (d) pyrrolo-annulated TTF derivatives I and J. (a) Host–guest equilibrium between π-electron-poor cyclophane 3 and different TTFs with their
Graphical Abstract
Figure 1: The two one-electron oxidation reactions of tetrathiafulvalene (TTF, 1) and the corresponding prope...
Figure 2: UV–vis spectra and photographs of TTF 2 in its three stable oxidation states (black line = 2, orang...
Figure 3: Structure and conformations of two TTF dimers in solution, the mixed-valence and the radical-cation...
Figure 4: (a) The isomerism problem of TTF. (b)–(d) Major synthetic breakthroughs for the construction of TTF...
Figure 5: (a) Host–guest equilibrium between π-electron-poor cyclophane 3 and different TTFs with their corre...
Figure 6: TTF complexes with different host molecules.
Figure 7: Stable TTF (a) radical-cation and (b) mixed-valence dimers in confined molecular spaces.
Figure 8: A “three-pole supramolecular switch”: Controlled by its oxidation state, TTF (1) jumps back and for...
Figure 9: Redox-controlled closing and opening motion of the artificial molecular lasso 12.
Figure 10: Graphical illustration how a non-degenerate TTF-based shuttle works under electrochemical operation....
Figure 11: The first TTF-based rotaxane 13.
Figure 12: A redox-switchable bistable molecular shuttle 14.
Figure 13: The redox-switchable cyclodextrin-based rotaxane 15.
Figure 14: The redox-switchable non-ionic rotaxane 16 with a pyromellitic diimide macrocycle.
Figure 15: The redox-switchable TTF rotaxane 17 based on a crown/ammonium binding motif.
Figure 16: Structure and operation of the electro- and photochemically switchable rotaxane 18 which acts as po...
Figure 17: (a) The redox-switchable rotaxane 19 with a donor–acceptor pair which is stable in five different s...
Figure 18: Schematic representation of a molecular electronic memory based on a bistable TTF-based rotaxane. (...
Figure 19: Schematic representation of bending motion of a microcantilever beam with gold surface induced by o...
Figure 20: TTF-dimer interactions in a redox-switchable tripodal [4]rotaxane 22.
Figure 21: (a) A molecular friction clutch 23 which can be operated by electrochemical stimuli. (b) Schematic ...
Figure 22: Fusion between rotaxane and catenane: a [3]rotacatenane 24 which can stabilize TTF dimers.
Figure 23: The first TTF-based catenane 25.
Figure 24: Electrochemically controlled circumrotation of the bistable catenane 26.
Figure 25: A tristable switch based on the redox-active [2]catenane 27 with three different stations.
Figure 26: Structure of catenane-functionalized MOF NU-1000 [108] with structural representation of subcomponents. ...
Figure 27: (a) [3]Catenanes 29 and 30 which can stabilize mixed-valence or radical-cation dimers of TTF. (b) S...
From supramolecular chemistry to the nucleosome: studies in biomolecular recognition
- Marcey L. Waters
Beilstein J. Org. Chem. 2016, 12, 1863–1869, doi:10.3762/bjoc.12.175
- interests. (a) Cyclophane receptors from Dennis Dougherty’s group in the late ‘80’s and early ‘90’s that demonstrated cation–π interactions [2]. (b) Cyclophane receptors from the Diederich group in the late ‘80’s and early ‘90’s that demonstrated the “nonclassical hydrophobic effect” [3]. (c) The Hunter
Graphical Abstract
Figure 1: (a) Frodo the dog (copyright to MLW). (b) Ron Waters in an A6 in 1961 at the age of 26 (reproduced ...
Figure 2: The Wulff–Dötz reaction.
Figure 3: Work by others that inspired my interests. (a) Cyclophane receptors from Dennis Dougherty’s group i...
Figure 4: (a) Model β-hairpin for investigation of aromatic interactions. (b) Examples of noncovalent interac...
Figure 5: (a) A clay model of our WKWK peptide (aka “Saratide”) made by Jes Park, a former graduate student i...
Figure 6: (a) Binding pocket of the Drosophila HP1 chromodomain (blue) bound to trimethyllysine (orange), PDB...
Figure 7: Dynamic combinatorial chemistry [41,42].
Smart molecules for imaging, sensing and health (SMITH)
- Bradley D. Smith
Beilstein J. Org. Chem. 2015, 11, 2540–2548, doi:10.3762/bjoc.11.274
- kinetic and thermodynamic properties. The nanomolar affinity in water is exceptionally strong for a synthetic cyclophane host molecule, and it is driven by a large favorable change in enthalpy. The two oxygen atoms on the encapsulated squaraine dye form hydrogen bonds to the four macrocycle NH residues
Graphical Abstract
Figure 1: The author as a teenager in his school uniform, but on the nearby Myrtleford golf course.
Scheme 1: Chronological progression of Smith group research projects.
Scheme 2: Molecular transporters promote translocation of ions or hydrophilic biomolecules across a synthetic...
Figure 2: (left) Association of ZnDPA probe with phosphatidylserine head group. (middle) False colored fluore...
Scheme 3: Macrocyclic receptor that binds solvent separated ion-pairs.
Scheme 4: Trapping a macrocyclic receptor containing a reactive ion-pair produces an interlocked [2]rotaxane.
Figure 3: (left) General structure of a squaraine rotaxane dye. (right) Fluorescence image of a living mouse ...
Scheme 5: (top) Basis of Synthavidin technology. A fluorescent squaraine dye that is flanked by PEG chains ca...
Figure 4: The author as director of the Notre Dame Integrated Imaging Facility.
Recent highlights in biosynthesis research using stable isotopes
- Jan Rinkel and
- Jeroen S. Dickschat
Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271
- benzene ring includes intermediate loss of aromaticity followed by rearomatization during the formation of the cyclophane ring [51]. However, a recently investigated example shows, that breaking the aromatic character of a phenyl ring is not necessary for building up a bended aryl ether in a biological
Graphical Abstract
Figure 1: Structures of lovastatin (1), aflatoxin B1 (2) and amphotericin B (3).
Scheme 1: a) Structure of rhizoxin (4). b) Two possible mechanisms of chain branching catalysed by a branchin...
Scheme 2: Structure of coelimycin P1 (8) and proposed biosynthetic formation from the putative PKS produced a...
Scheme 3: Structure of trioxacarcin A (9) with highlighted carbon origins of the polyketide core from acetate...
Scheme 4: Proposed biosynthetic assembly of clostrubin A (12). Bold bonds show intact acetate units.
Figure 2: Structure of forazoline A (13).
Figure 3: Structures of tyrocidine A (14) and teixobactin (15).
Figure 4: Top: Structure of the NRPS product kollosin A (16) with the sequence N-formyl-D-Leu-L-Ala-D-Leu-L-V...
Scheme 5: Proposed biosynthesis of aspirochlorine (20) via 18 and 19.
Scheme 6: Two different macrocyclization mechanisms in the biosynthesis of pyrrocidine A (24).
Figure 5: Structure of thiomarinol A (27). Bold bonds indicate carbon atoms derived from 4-hydroxybutyrate.
Figure 6: Structures of artemisinin (28), ingenol (29) and paclitaxel (30).
Figure 7: The revised (31) and the previously suggested (32) structure of hypodoratoxide and the structure of...
Figure 8: Structure of the two interconvertible conformers of (1(10)E,4E)-germacradien-6-ol (34) studied with...
Scheme 7: Proposed cyclization mechanism of corvol ethers A (42) and B (43) with the investigated reprotonati...
Scheme 8: Predicted (top) and observed (bottom) 13C-labeling pattern in cyclooctatin (45) after feeding of [U-...
Scheme 9: Proposed mechanism of the cyclooctat-9-en-7-ol (52) biosynthesis catalysed by CotB2. Annotated hydr...
Scheme 10: Cyclization mechanism of sesterfisherol (59). Bold lines indicate acetate units; black circles repr...
Scheme 11: Cyclization mechanisms to pentalenene (65) and protoillud-6-ene (67).
Scheme 12: Reactions of chorismate catalyzed by three different enzyme subfamilies. Oxygen atoms originating f...
Scheme 13: Incorporation of sulfur into tropodithietic acid (72) via cysteine.
Scheme 14: Biosynthetic proposal for the starter unit of antimycin biosynthesis. The hydrogens at positions R1...
Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics
- Kevin Lafaye,
- Cyril Bosset,
- Lionel Nicolas,
- Amandine Guérinot and
- Janine Cossy
Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241
- of 2,6-disubstituted pyridine 60 was treated with GI, the expected macrocycle 61 was obtained (51%) together with the dimeric cyclophane 62 (20%). The authors explained that the sulfone moieties facilitated the RCM by steering the alkenyl chains into a favorable conformation, but it also may be
Graphical Abstract
Figure 1: Some ruthenium catalysts for metathesis reactions.
Scheme 1: Decomposition of methylidenes 1 and 2.
Scheme 2: Deactivation of G-HII in the presence of ethylene.
Scheme 3: Reaction between GI/GII and n-BuNH2.
Scheme 4: Reaction of GII with amines a–d.
Scheme 5: Amine-induced decomposition of GII methylidene 2.
Scheme 6: Amine-induced decomposition of GII in RCM conditions.
Scheme 7: Deactivation of methylidene 2 in the presence of pyridine.
Scheme 8: Reaction of G-HII with various amines.
Scheme 9: Formation of olefin 22 from styrene.
Scheme 10: Hypothetic deactivation pathway of G-HII.
Scheme 11: RCM of dienic pyridinium salts.
Scheme 12: Synthesis of polycyclic scaffolds using RCM.
Scheme 13: Enyne ring-closing metathesis.
Scheme 14: Synthesis of (R)-(+)-muscopyridine using a RCM strategy.
Scheme 15: Synthesis of a tris-pyrrole macrocycle.
Scheme 16: Synthesis of a bicyclic imidazole.
Scheme 17: RCM using Schrock’s catalyst 44.
Scheme 18: Synthesis of 1,6-pyrido-diazocine 46 by using a RCM.
Scheme 19: Synthesis of fused pyrimido-azepines through RCM.
Scheme 20: RCM involving alkenes containing various N-heteroaromatics.
Scheme 21: Synthesis of dihydroisoquinoline using a RCM.
Scheme 22: Formation of tricyclic compound 59.
Scheme 23: RCM in the synthesis of normuscopyridine.
Scheme 24: Synthesis of macrocycle 64.
Scheme 25: Synthesis of macrocycles possessing an imidazole group.
Scheme 26: Retrosynthesis of an analogue of erythromycin.
Scheme 27: Retrosynthesis of haminol A.
Scheme 28: CM involving 3-vinylpyridine 70 with 71 and vinylpyridine 70 with 73.
Scheme 29: Revised retrosynthesis of haminol A.
Scheme 30: CM between 78 and crotonaldehyde.
Scheme 31: Hypothesized deactivation pathway.
Scheme 32: CM involving an allyl sulfide containing a quinoline.
Scheme 33: CM involving allylic sulfide possessing a quinoxaline or a phenanthroline.
Scheme 34: CM between an acrylate and a 2-methoxy-5-bromo pyridine.
Scheme 35: Successful CM of an alkene containing a 2-chloropyridine.
Scheme 36: Variation of the substituent on the pyridine ring.
Scheme 37: CM involving alkenes containing a variety of N-heteroaromatics.
Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks
- Zhan-Ting Li
Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222
- ]catenane 6c with the tetracationic cyclophane holding one of the peripheral benzene rings [14]. The TTF unit in 6a and 6b adopted a stable cis or trans configuration, although typically the two configurations easily isomerize into each other in solution. Macrocycle 3 is a brown solid due to the existence
Graphical Abstract
Scheme 1: Proposed structures of complexes between 1a and 1b with 2.
Scheme 2: The formation of catenanes 6a–c.
Scheme 3: The structures of cantenanes 7a–c.
Scheme 4: The structures of dimer 8·8 and compounds 9 and 10.
Figure 1: X-ray structure of 10 showing a quadruple hydrogen-bonded dimeric motif [17].
Scheme 5: The structures of compounds 11a–g.
Figure 2: Zipper-featured folding motif of δ-peptides 11a–g driven by the cooperative donor–acceptor interact...
Scheme 6: The structures of compounds 12a–g and the formation of the helical conformation by the longer oligo...
Scheme 7: The structures of compounds 13a,b, 14, and 15a–d.
Scheme 8:
The structures of complex C60 ![[Graphic 1]](/bjoc/content/inline/1860-5397-11-222-i19.png?max-width=637&scale=1.18182)
16 and dynamic [2]catenane formed by compounds 17–19.
Scheme 9: The structure of homodimers 20a·20a and 20b·20b.
Scheme 10: The structures of foldamers 21 and 22a–c.
Scheme 11: Complexation-promoted hydrolysis of foldamer 23.
Scheme 12: The structure of foldamer 24.
Scheme 13: The structures of foldamers 24a–c.
Scheme 14: Proposed structures of heterodimers 25·28, 26·28, and 27·28.
Scheme 15: Proposed structure of complex formed by 29 and 30.
Scheme 16: The structures of polymers P31a,b and P32a–d.
Scheme 17: The structure of compound 33.
Scheme 18: The structure of compound 34.
[2.2]Paracyclophane derivatives containing tetrathiafulvalene moieties
- Laura G. Sarbu,
- Lucian G. Bahrin,
- Peter G. Jones,
- Lucian M. Birsa and
- Henning Hopf
Beilstein J. Org. Chem. 2015, 11, 1917–1921, doi:10.3762/bjoc.11.207
- (Figure 1). The molecular dimensions confirm the extensive p–π conjugation within the dithiocarbamate group; the N(1)–C(19) bond length is 1.341(3) Å, some 0.12 Å shorter than N(1)–C(20) and N(1)–C(21), which are essentially σ-bonds. The cyclophane group displays the usual indicators of strain (e.g
- -2-thione group relative to the cyclophane; the torsion angle C3–C4–C17–S3 is −45.9° in the first molecule but −142.4° in the second. CCDC-1412357 contains the supplementary crystallographic data for compound 6 (see also Supporting Information File 1). These data can be obtained free of charge from
Graphical Abstract
Scheme 1: Synthesis of 2-N,N-dialkylamino-4-([2.2]paracyclophan-4-yl)-1,3-dithiol-2-ylium perchlorates 5.
Figure 1: Molecular structure of compound 4a. Ellipsoids represent 30% probability levels. Selected molecular...
Scheme 2: Synthesis of tetrathiafulvalenes 7.
Figure 2: Molecular structure of compound 6 (two independent molecules). Ellipsoids represent 30% probability...
Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis
- David W. Manley and
- John C. Walton
Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173
- cyclophane 41b being formed in 23% yield along with 30% of 42b. Diacid 40c returned only the dialkane product 42c probably because the two reaction centers were held too far apart by the rigid p-xylene linker. Some other compound types have proved to be effective donors in SCPC, picking up h+ from the
Graphical Abstract
Figure 1: Production and utilization of h+ and e– by photoactivation of a semiconductor.
Figure 2: Photoredox activity of TiO2 with moist air.
Scheme 1: TiO2 promoted oxidation of phenanthrene [29].
Scheme 2: SCPC assisted additions of allylic compounds to diazines and imines [40-42].
Scheme 3: TiO2 promoted addition and addition–cyclization reactions of tert-amines with electron-deficient al...
Scheme 4: Reactions of amines promoted by Pt-TiO2 [48,49].
Scheme 5: P25 Promoted alkylations of N-phenylmaleimide with diverse carboxylic acids [53,54]. aAccompanied by R–R d...
Scheme 6: SCPC cyclizations of aryloxyacetic acids with suitably sited alkene acceptors [54]. aYields in brackets...
Scheme 7: TiO2 promoted reactions of aryloxyacetic acids with maleic anhydride and maleimides [53,54].
Scheme 8: Photoredox addition–cyclization reactions of aryloxyacetic and related acids promoted by maleimide [63]....
Scheme 9: SCPC promoted homo-couplings and macrocyclizations with carboxylic acids [64].
Scheme 10: TiO2 promoted alkylations of alkenes with silanes [66] and thiols [67].
Scheme 11: TiO2 reduction of a nitrochromenone derivative [70].
Scheme 12: TiO2 mediated hydrodehalogenations and cyclizations of organic iodides [71].
Scheme 13: TiO2 promoted hydrogenations of maleimides, maleic anhydride and aromatic aldehydes [79].
Scheme 14: Mechanistic sketch of SCPC hydrogenation of aryl aldehydes.
Design and synthesis of hybrid cyclophanes containing thiophene and indole units via Grignard reaction, Fischer indolization and ring-closing metathesis as key steps
- Sambasivarao Kotha,
- Ajay Kumar Chinnam and
- Mukesh E. Shirbhate
Beilstein J. Org. Chem. 2015, 11, 1514–1519, doi:10.3762/bjoc.11.165
- via Grignard addition, Fischer indolization and ring-closing metathesis as key steps. Keywords: cyclophane; Grignard reaction; Fischer indolization; ring-closing metathesis; Introduction Modern olefin metathesis catalysts enable a late stage ring-closing step starting with bisolefinic substrates
- cyclophanes the development of powerful and general synthetic methods is highly desirable. Herein, we report a new approach to thiophene- and indole-containing hybrid cyclophane derivatives via Grignard addition, Fischer indolization and RCM as key steps. Strategy The retrosynthetic strategy to the target
- cyclophane 1 containing the thiophene and indole moieties is shown in Figure 1. Here, we conceived thiophene-containing diolefin 3 as a possible synthon to assemble the target molecule 1 via 2. Route A involves an RCM of 3 followed by Fischer indolization of 2 (Figure 1). Alternatively, Fischer indolization
Graphical Abstract
Figure 1: Retrosynthetic approach to hybrid cyclophane derivative 1.
Scheme 1: Attempted synthesis of thiophenophane derivative 2.
Scheme 2: Synthesis of hybrid cyclophane 1.
Figure 2: The molecular crystal structure of 1 with 50% probability [41].
Scheme 3: Attempted synthesis of thiophenophane derivative 2a.
Scheme 4: Synthesis of cyclophane 1a with a thiophene and an indole moiety.
Selected synthetic strategies to cyclophanes
- Sambasivarao Kotha,
- Mukesh E. Shirbhate and
- Gopalkrushna T. Waghule
Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142
- , we have included a strategy where the reaction was used for assembling the cyclophane skeleton for further functionalization. In several instances, after the cyclophane is made several popular reactions are used and these are not covered here. We included various natural products related to
- cyclophanes. To keep the length of the review at a manageable level the literature related to orthocyclophanes was not included. Keywords: addition reactions; coupling reactions; cyclophane; metathesis; muscopyridine; name reactions; natural products; Indroduction Cyclophanes [1][2][3][4][5][6][7][8][9][10
- attachment of the alkyl chain to the aromatic system. In this review we are not discussing orthocyclophanes but rather focus on meta- and paracyclophanes only. The aromatic ring present in the cyclophane system can be either heterocyclic or carbocylic in nature. If there is a heteroatom present in the
Graphical Abstract
Figure 1: General representation of cyclophanes.
Figure 2: cyclophanes one or more with heteroatom.
Figure 3: Metathesis catalysts 12–17 and C–C coupling catalyst 18.
Figure 4: Natural products containing the cyclophane skeleton.
Figure 5: Turriane family of natural products.
Scheme 1: Synthesis of [3]ferrocenophanes through Mannich reaction. Reagents and conditions: (i) excess HNMe2...
Scheme 2: Synthesis of cyclophanes through Michael addition. Reagents and conditions: (i) xylylene dibromide,...
Scheme 3: Synthesis of normuscopyridine analogue 37 through an oxymercuration–oxidation strategy. Reagents an...
Scheme 4: Synthesis of tribenzocyclotriyne 39 through Castro–Stephens coupling reaction. Reagents and conditi...
Scheme 5: Synthesis of cyclophane 43 through Glaser–Eglinton coupling. Reagents and conditions: (i) 9,10-bis(...
Scheme 6: Synthesis of the macrocyclic C-glycosyl cyclophane through Glaser coupling. Reagents and conditions...
Scheme 7: Synthesis of cyclophane-containing complex 49 through Glaser–Eglinton coupling reaction. Reagents a...
Scheme 8: Synthesis of cyclophane 53 through Glaser–Eglinton coupling. Reagents and conditions: (i) K2CO3, ac...
Figure 6: Cyclophanes 54–56 that have been synthesized through Glaser–Eglinton coupling.
Figure 7: Synthesis of tetrasubstituted [2.2]paracyclophane 57 and chiral cyclophyne 58 through Eglinton coup...
Scheme 9: Synthesis of cyclophane through Glaser–Hay coupling reaction. Reagents and conditions: (i) CuCl2 (1...
Scheme 10: Synthesis of seco-C/D ring analogs of ergot alkaloids through intramolecular Heck reaction. Reagent...
Scheme 11: Synthesis of muscopyridine 73 via Kumada coupling. Reagents and conditions: (i) 72, THF, ether, 20 ...
Scheme 12: Synthesis of the cyclophane 79 via McMurry coupling. Reagents and conditions: (i) 75, decaline, ref...
Scheme 13: Synthesis of stilbenophane 81 via McMurry coupling. Reagents and conditions: (i) TiCl4, Zn, pyridin...
Scheme 14: Synthesis of stilbenophane 85 via McMurry coupling. Reagents and conditions: (i) NBS (2 equiv), ben...
Figure 8: List of cyclophanes prepared via McMurry coupling reaction as a key step.
Scheme 15: Synthesis of paracyclophane by cross coupling involving Pd(0) catalyst. Reagents and conditions: (i...
Scheme 16: Synthesis of the cyclophane 112 via the pinacol coupling and 113 by RCM. Reagents and conditions: (...
Scheme 17: Synthesis of cyclophane derivatives 122a–c via Sonogoshira coupling. Reagents and conditions: (i) C...
Scheme 18: Synthesis of cyclophane 130 via Suzuki–Miyaura reaction as a key step. Reagents and conditions: (i)...
Scheme 19: Synthesis of the mycocyclosin via Suzuki–Miyaura cross coupling. Reagents and conditions: (i) benzy...
Scheme 20: Synthesis of cyclophanes via Wurtz coupling reaction Reagents and conditions: (i) PhLi, Et2O, C6H6,...
Scheme 21: Synthesis of non-natural glycophanes using alkyne metathesis. Reagents and conditions: (i) G-I (12)...
Figure 9: Synthesis of cyclophanes via ring-closing alkyne metathesis.
Scheme 22: Synthesis of crownophanes by cross-enyne metathesis. Reagents and conditions: (i) G-II (13), 5 mol ...
Scheme 23: Synthesis of (−)-cylindrocyclophanes A (156) and (−)-cylindrocyclophanes F (155). Reagents and cond...
Scheme 24: Synthesis of cyclophane 159 derivatives via SM cross-coupling and RCM. Reagents and conditions: (i)...
Scheme 25: Sexithiophene synthesis via cross metathesis. Reagents and conditions: (i) 161, Pd(PPh3)4, K2CO3, T...
Scheme 26: Synthesis of pyrrole-based cyclophane using enyne metathesis. Reagents and conditions: (i) Se, chlo...
Scheme 27: Synthesis of macrocyclic derivatives by RCM. Reagents and conditions: (i) G-I/G-II, CH2Cl2, 0.005 M...
Scheme 28: Synthesis of enantiopure β-lactam-based dienyl bis(dihydrofuran) 179. Reagents and conditions: (i) ...
Scheme 29: Synthesis of a [1.1.6]metaparacyclophane derivative 183 via SM cross coupling. Reagents and conditi...
Scheme 30: Synthesis of a [1.1.6]metaparacyclophane derivative 190 via SM cross coupling. Reagents and conditi...
Scheme 31: Template-promoted synthesis of cyclophanes involving RCM. Reagents and conditions: (i) acenaphthene...
Scheme 32: Synthesis of [3.4]cyclophane derivatives 200 via SM cross coupling and RCM. Reagents and conditions...
Figure 10: Examples for cyclophanes synthesized by RCM.
Scheme 33: Synthesis of the longithorone C framework assisted by fluorinated auxiliaries. Reagents and conditi...
Scheme 34: Synthesis of the longithorone framework via RCM. Reagents and conditions: (i) 213, NaH, THF, rt, 10...
Scheme 35: Synthesis of floresolide B via RCM as a key step. Reagents and conditions: (i) G-II (13, 0.1 equiv)...
Scheme 36: Synthesis of normuscopyridine (223) by the RCM strategy. Reagents and condition: (i) Mg, THF, hexen...
Scheme 37: Synthesis of muscopyridine (73) via RCM. Reagents and conditions: (i) 225, NaH, THF, 0 °C to rt, 1....
Scheme 38: Synthesis of muscopyridine (73) via RCM strategy. Reagents and conditions: (i) NaH, n-BuLi, 5-bromo...
Scheme 39: Synthesis of pyridinophane derivatives 223 and 245. Reagents and conditions: (i) PhSO2Na, TBAB, CH3...
Scheme 40: Synthesis of metacyclophane derivatives 251 and 253. Reagents and conditions: (i) 240, NaH, THF, rt...
Scheme 41: Synthesis of normuscopyridine and its higher analogues. Reagents and conditions: (i) alkenyl bromid...
Scheme 42: Synthesis of fluorinated ferrocenophane 263 via a [2 + 2] cycloaddition. Reagents and conditions: (...
Scheme 43: Synthesis of [2.n]metacyclophanes 270 via a [2 + 2] cycloaddition. Reagents and conditions: (i) Ac2...
Scheme 44: Synthesis of metacyclophane 273 by a [2 + 2 + 2] co-trimerization. Reagents and conditions: (i) [Rh...
Scheme 45: Synthesis of paracyclophane 276 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditions: ...
Scheme 46: Synthesis of cyclophane 278 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditions: (i) ...
Scheme 47: Synthesis of cyclophane 280 via a [2 + 2 + 2] cycloaddition. Reagents and conditions: (i) [(Rh(cod)(...
Scheme 48: Synthesis of taxane framework by a [2 + 2 + 2] cycloaddition. Reagents and conditions: (i) Cp(CO)2 ...
Scheme 49: Synthesis of cyclophane 284 and 285 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditio...
Scheme 50: Synthesis of pyridinophanes 293a,b and 294a,b via a [2 + 2 + 2] cycloaddition. Reagents and conditi...
Scheme 51: Synthesis of pyridinophanes 296 and 297 via a [2 + 2 + 2] cycloaddition. Reagents and conditions: (...
Scheme 52: Synthesis of triazolophane by a 1,3-dipolar cycloaddition. Reagents and conditions: (i) propargyl b...
Scheme 53: Synthesis of glycotriazolophane 309 by a click reaction. Reagents and conditions: (i) LiOH, H2O, Me...
Figure 11: Cyclophanes 310 and 311 prepared via click chemistry.
Scheme 54: Synthesis of cyclophane via the Dötz benzannulation. Reagents and conditions: (i) THF, 100 °C, 12 h...
Scheme 55: Synthesis of [6,6]metacyclophane by a Dötz benzannulation. Reagents and conditions: (i) THF, 100 °C...
Scheme 56: Synthesis of cyclophanes by a Dötz benzannulation. Reagents and conditions: (i) THF, 65 °C, 3 h; (i...
Scheme 57: Synthesis of muscopyridine (73) via an intramolecular DA reaction of ketene. Reagents and condition...
Scheme 58: Synthesis of bis[10]paracyclophane 336 via Diels–Alder reaction. Reagents and conditions: (i) DMAD,...
Scheme 59: Synthesis of [8]paracyclophane via DA reaction. Reagents and conditions: (i) maleic anhydride, 3–5 ...
Scheme 60: Biomimetic synthesis of (−)-longithorone A. Reagents and conditions: (i) Me2AlCl, CH2Cl2, −20 °C, 7...
Scheme 61: Synthesis of sporolide B (349) via a [4 + 2] cycloaddition reaction. Reagents and conditions: (i) P...
Scheme 62: Synthesis of the framework of (+)-cavicularin (352) via a [4 + 2] cycloaddition. Reagents and condi...
Scheme 63: Synthesis of oxazole-containing cyclophane 354 via Beckmann rearrangement. Reagents and conditions:...
Scheme 64: Synthesis of cyclophanes 360a–c via benzidine rearrangement. Reagents and conditions: (i) 356a–d, K2...
Scheme 65: Synthesis of cyclophanes 365a–c via benzidine rearrangement. Reagents and conditions: (i) BocNHNH2,...
Scheme 66: Synthesis of metacyclophane 367 via Ciamician–Dennstedt rearrangement. Reagents and conditions: (i)...
Scheme 67: Synthesis of cyclophane by tandem Claisen rearrangement and RCM as key steps. Reagents and conditio...
Scheme 68: Synthesis of cyclophane derivative 380. Reagents and conditions: (i) K2CO3, CH3CN, allyl bromide, r...
Scheme 69: Synthesis of metacyclophane via Cope rearrangement. Reagents and conditions: (i) MeOH, NaBH4, rt, 1...
Scheme 70: Synthesis of cyclopropanophane via Favorskii rearrangement. Reagents and conditions: (i) Br2, CH2Cl2...
Scheme 71: Cyclophane 389 synthesis via photo-Fries rearrangement. Reagents and conditions: (i) DMAP, EDCl/CHCl...
Scheme 72: Synthesis of normuscopyridine (223) via Schmidt rearrangement. Reagents and conditions: (i) ethyl s...
Scheme 73: Synthesis of crownophanes by tandem Claisen rearrangement. Reagents and conditions: (i) diamine, Et3...
Scheme 74: Attempted synthesis of cyclophanes via tandem Claisen rearrangement and RCM. Reagents and condition...
Scheme 75: Synthesis of muscopyridine via alkylation with 2,6-dimethylpyridine anion. Reagents and conditions:...
Scheme 76: Synthesis of cyclophane via Friedel–Craft acylation. Reagents and conditions: (i) CS2, AlCl3, 7 d, ...
Scheme 77: Pyridinophane 418 synthesis via Friedel–Craft acylation. Reagents and conditions: (i) 416, AlCl3, CH...
Scheme 78: Cyclophane synthesis involving the Kotha–Schölkopf reagent 421. Reagents and conditions: (i) NBS, A...
Scheme 79: Cyclophane synthesis involving the Kotha–Schölkopf reagent 421. Reagents and conditions: (i) BEMP, ...
Scheme 80: Cyclophane synthesis by coupling with TosMIC. Reagents and conditions: (i) (a) ClCH2OCH3, TiCl4, CS2...
Scheme 81: Synthesis of diaza[32]cyclophanes and triaza[33]cyclophanes. Reagents and conditions: (i) DMF, NaH,...
Scheme 82: Synthesis of cyclophane 439 via acyloin condensation. Reagents and conditions: (i) Na, xylene, 75%;...
Scheme 83: Synthesis of multibridged binuclear cyclophane 442 by aldol condensation. Reagents and conditions: ...
Scheme 84: Synthesis of various macrolactones. Reagents and conditions: (i) iPr2EtN, DMF, 77–83%; (ii) TBDMSCl...
Scheme 85: Synthesis of muscone and muscopyridine via Yamaguchi esterification. Reagents and conditions: (i) 4...
Scheme 86: Synthesis of [5]metacyclophane via a double elimination reaction. Reagents and conditions: (i) LiBr...
Figure 12: Cyclophanes 466–472 synthesized via Hofmann elimination.
Scheme 87: Synthesis of cryptophane via Baylis–Hillman reaction. Reagents and conditions: (i) methyl acrylate,...
Scheme 88: Synthesis of cyclophane 479 via double Chichibabin reaction. Reagents and conditions: (i) excess 478...
Scheme 89: Synthesis of cyclophane 483 via double Chichibabin reaction. Reagents and conditions: (i) 481, OH−;...
Scheme 90: Synthesis of cyclopeptide via an intramolecular SNAr reaction. Reagents and conditions: (i) TBAF, T...
Scheme 91: Synthesis of muscopyridine (73) via C-zip ring enlargement reaction. Reagents and conditions: (i) H...
Figure 13: Mechanism of the formation of compound 494.
Scheme 92: Synthesis of indolophanetetraynes 501a,b using the Nicholas reaction as a key step. Reagents and co...
Scheme 93: Synthesis of cyclophane via radical cyclization. Reagents and conditions: (i) cyclododecanone, phen...
Scheme 94: Synthesis of (−)-cylindrocyclophanes A (156) and (−)-cylindrocyclophanes F (155). Reagents and cond...
Scheme 95: Cyclophane synthesis via Wittig reaction. Reagents and conditions: (i) LiOEt (2.1 equiv), THF, −78 ...
Figure 14: Representative examples of cyclophanes synthesized via Wittig reaction.
Scheme 96: Synthesis of the [6]paracyclophane via isomerization of Dewar benzene. Reagents and conditions: (i)...
The preparation of new functionalized [2.2]paracyclophane derivatives with N-containing functional groups
- Henning Hopf,
- Swaminathan Vijay Narayanan and
- Peter G. Jones
Beilstein J. Org. Chem. 2015, 11, 437–445, doi:10.3762/bjoc.11.50
- preparation of various cyclophanes bearing substituents with nitrogen-containing functional groups, e.g., the pseudo-ortho diamine 8, the bis secondary amine 23, and the crownophanes 18 and 19. Several of these new cyclophane derivatives (18, 19, 22, 26, 28) have been characterized by X-ray structural
- rings, [Sar]n, n again ranging from 1 to 8. Of course, these two types of substituents will display different reactivities since they are bonded to differently hybridized carbon atoms. In a way, the rigid cyclophane carbon framework may be regarded as a hexadecavalent “superatom” that can bind up to 16
- cyclophane molecule, all pointing in the same direction, a structure results that bears functional groups on the one half of the molecule whereas the other consists of aliphatic and aromatic C–H bonds only. It is very likely that these geometries will have a strong influence on chemical and physical
Graphical Abstract
Figure 1: A selection of highly substituted/functionalized [2.2]paracyclophanes.
Figure 2: A selection of [2.2]paracyclophanes carrying several nitrogen-containing substituents.
Scheme 1: The preparation of 4,12-diamino[2.2]paracyclophane (8).
Scheme 2: Preparation of cyclic and acyclic urethanes from 4,12-diisocyanato[2.2]paracyclophane (16).
Figure 3: (a, above): The molecule of compound 18 in the crystal; ellipsoids represent 50% probability levels...
Scheme 3: LiAlH4-reduction of crownophane 18.
Figure 4: (a, above): The molecule of compound 22 in the crystal; ellipsoids represent 30% probability levels...
Scheme 4: The preparation of several derivatives of 4,16-dicarboxy[2.2]paracyclophane (25) carrying N-contain...
Figure 5: The molecule of compound 26 in the crystal; ellipsoids represent 50% probability levels. Only the a...
Figure 6: (a, above): The molecule of compound 28 in the crystal; ellipsoids represent 50% probability levels...
Selenium halide-induced bridge formation in [2.2]paracyclophanes
- Laura G. Sarbu,
- Henning Hopf,
- Peter G. Jones and
- Lucian M. Birsa
Beilstein J. Org. Chem. 2014, 10, 2550–2555, doi:10.3762/bjoc.10.266
- neglected so far. Functional groups in pseudo-geminally substituted [2.2]paracyclophanes often undergo highly specific reactions. This is due to the rigid framework and the short distance between the two aromatic rings within the [2.2]paracyclophane unit. Thus, unsaturated cyclophane bis(esters) undergo
- :1.4. It is interesting to note that the synthesis of the [2.3.2](1,2,4)cyclophane derivative 5 has been previously reported as the result of bromine addition to bis(acetylene) 1, in 87% yield [13]. In both experiments, the formation of elemental red selenium was observed. The unexpected reaction
- dichloride or selenium dibromide, we isolated only the [2.3.2](1,2,4)cyclophane derivatives 2, 3 and 5, 6, respectively; no traces of tetrahalides 4 and 7 were detected (Table 1, entries 2 and 4). Although unexpected, the lack of tetrahalides from these experiments proved later to be of significant
Graphical Abstract
Scheme 1: Reactions of selenium dichloride and selenium dibromide with pseudo-geminal bis(acetylene) 1.
Scheme 2: Reaction of phenylselenyl chloride with pseudo-geminal bis(acetylene) 1.
Scheme 3: Plausible reaction mechanism for the addition of phenylselenyl chloride to pseudo-geminal bis(acety...
Scheme 4: Reactions of selenium dichloride and selenium dibromide with 4,13-bis(propyn-1-yl)[2.2]paracyclopha...
Figure 1: Molecular structure of compound 13. Ellipsoids represent 50% probability levels. Selected molecular...
Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation
- Henning Hopf,
- Swaminathan Vijay Narayanan and
- Peter G. Jones
Beilstein J. Org. Chem. 2014, 10, 2021–2026, doi:10.3762/bjoc.10.210
- in the past on numerous cyclophane derivatives bearing condensed four- to seven-membered rings, as shown by the representative examples of 1 (E = CO2CH3) [2], 2 [3], 3 [4], and 4 [5]. Many of these compounds possess interesting structural and spectroscopic properties, and can be used as substrates
- of the cyclophane framework (endo-orientation) or to the outer section of the derivative (exo-orientation). Thus altogether the six different diastereomers 10–15 result. Results and Discussion As the experiment shows (treatment of 9 with either sodium hydroxide in methanol or aniline in methanol
- cyclophane core. In other words, the oxygen atom faces a methylene hydrogen atom of the bridge. In principle the alternative orientation is also possible, with the methyl substituent taking this position. A comparable situation has been observed for the 4-acetyl derivative of [2.2]paracyclophane, with the
Graphical Abstract
Scheme 1: [2.2]Paracyclophane derivatives with annelated alicyclic rings.
Scheme 2: The formation of the tetraketone 9 by a Diels–Alder addition.
Scheme 3: The possible structures of the aldols formed from 9.
Figure 1: Structure of 12·CDCl3 in the crystal. Ellipsoids represent 50% probability levels. Selected bond le...
Scheme 4: The mechanism of the aldol cyclization.
Scheme 5: Dehydration of the aldol 12.
Scheme 6: Dehydration of the aldol 15.
Figure 2: Structure of compound 21 in the crystal. Ellipsoids represent 50% probability levels. Selected bond...
Building complex carbon skeletons with ethynyl[2.2]paracyclophanes
- Ina Dix,
- Lidija Bondarenko,
- Peter G. Jones,
- Thomas Oeser and
- Henning Hopf
Beilstein J. Org. Chem. 2014, 10, 2013–2020, doi:10.3762/bjoc.10.209
- extensive column chromatography/recrystallization. Isomer 11 is chiral and could be separated on a column impregnated with cellulose tris(3,5-dimethylphenyl)carbamate. The bridge-extended cyclophane precursor 18 furnished the ring-enlarged cyclophanes 19 and 20 on Glaser–Hay coupling. Cross-coupling of 4
- 12 displays the “parallel” geometry of the extra bridges, and the two paracyclophane units are indeed exactly parallel to each other by symmetry. The cyclophane rings of the asymmetric unit are twisted by 8.4°. The extra bridges are again bowed, and the angles depart slightly more from 180° (167° at
- (r.m.s.d. 0.12 Å). The bridges are “parallel”, although the angle between the two cyclophane units is ca. 16° (the average of the interplanar angles between the two halves across the pseudo-mirror plane). The two paracyclophane units each show the usual patterns of strain; the twist angles are 1.4 and 4.4
Graphical Abstract
Scheme 1: Planar and layered ethynyl aromatics as building blocks for extended aromatic structures.
Scheme 2: Previous coupling experiments with pseudo-ortho-diethynyl[2.2]paracyclophane 4.
Scheme 3: Glaser coupling of pseudo-gem-diethynyl[2.2]paracyclophane 2.
Scheme 4: Glaser coupling of pseudo-ortho-diethynyl[2.2]paracyclophane, 4.
Figure 1: Above: The molecule of compound 11 in the crystal; ellipsoids represent 30% probability levels. Onl...
Figure 2: Above: The molecule of compound 12 in the crystal; ellipsoids represent 50% probability levels. Onl...
Scheme 5: Sonogashira coupling of aldehyde 13 with ortho-diiodobenzene (14).
Scheme 6: Preparation of benzologs of dimers 11/12.
Figure 3: Above: The molecule of compound 19 in the crystal; ellipsoids represent 50% probability levels. Sol...
Figure 4: Above: One of the three independent molecules of compound 20 in the crystal; ellipsoids represent 3...
Scheme 7: Cross dimerization of 1 and 4.
Figure 5: The molecule of compound 22 in the crystal; ellipsoids represent 50% probability levels.
Scheme 8: An attempt to prepare a biphenylenophane.
Figure 6: The molecule of compound 26 in the crystal; ellipsoids represent 50% probability levels.
Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics
- Gijs Koopmanschap,
- Eelco Ruijter and
- Romano V.A. Orru
Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50
Graphical Abstract
Scheme 1: The proposed mechanism of the Passerini reaction.
Scheme 2: The PADAM-strategy to α-hydroxy-β-amino amide derivatives 7. An additional oxidation provides α-ket...
Scheme 3: The general accepted Ugi-mechanism.
Scheme 4: Three commonly applied Ugi/cyclization approaches. a) UDC-process, b) UAC-sequence, c) UDAC-combina...
Scheme 5: Ugi reaction that involves the condensation of Armstrong’s convertible isocyanide.
Scheme 6: Mechanism of the U-4C-3CR towards bicyclic β-lactams.
Scheme 7: The Ugi 4C-3CR towards oxabicyclo β-lactams.
Scheme 8: Ugi MCR between an enantiopure monoterpene based β-amino acid, aldehyde and isocyanide resulting in...
Scheme 9: General MCR for β-lactams in water.
Scheme 10: a) Ugi reaction for β-lactam-linked peptidomimetics. b) Varying the β-amino acid resulted in β-lact...
Scheme 11: Ugi-4CR followed by a Pd-catalyzed Sn2 cyclization.
Scheme 12: Ugi-3CR of dipeptide mimics from 2-substituted pyrrolines.
Scheme 13: Joullié–Ugi reaction towards 2,5-disubstituted pyrrolidines.
Scheme 14: Further elaboration of the Ugi-scaffold towards bicyclic systems.
Scheme 15: Dihydroxyproline derivatives from an Ugi reaction.
Scheme 16: Diastereoselective Ugi reaction described by Banfi and co-workers.
Scheme 17: Similar Ugi reaction as in Scheme 16 but with different acids and two chiral isocyanides.
Scheme 18: Highly diastereoselective synthesis of pyrrolidine-dipeptoids via a MAO-N/MCR-procedure.
Scheme 19: MAO-N/MCR-approach towards the hepatitis C drug telaprevir.
Scheme 20: Enantioselective MAO-U-3CR procedure starting from chiral pyrroline 64.
Scheme 21: Synthesis of γ-lactams via an UDC-sequence.
Scheme 22: Utilizing bifunctional groups to provide bicyclic γ-lactam-ketopiperazines.
Scheme 23: The Ugi reaction provided both γ- as δ-lactams depending on which inputs were used.
Scheme 24: The sequential Ugi/RCM with olefinic substrates provided bicyclic lactams.
Scheme 25: a) The structural and dipole similarities of the triazole unit with the amide bond. b) The copper-c...
Scheme 26: The Ugi/Click sequence provided triazole based peptidomimetics.
Scheme 27: The Ugi/Click reaction as described by Nanajdenko.
Scheme 28: The Ugi/Click-approach by Pramitha and Bahulayan.
Scheme 29: The Ugi/Click-combination by Niu et al.
Scheme 30: Triazole linked peptidomimetics obtained from two separate MCRs and a sequential Click reaction.
Scheme 31: Copper-free synthesis of triazoles via two MCRs in one-pot.
Scheme 32: The sequential Ugi/Paal–Knorr reaction to afford pyrazoles.
Scheme 33: An intramolecular Paal–Knorr condensation provided under basic conditions pyrazolones.
Scheme 34: Similar cyclization performed under acidic conditions provided pyrazolones without the trifluoroace...
Scheme 35: The Ugi-4CR towards 2,4-disubstituted thiazoles.
Scheme 36: Solid phase approach towards thiazoles.
Scheme 37: Reaction mechanism of formation of thiazole peptidomimetics containing an additional β-lactam moiet...
Scheme 38: The synthesis of the trisubstituted thiazoles could be either performed via an Ugi reaction with pr...
Scheme 39: Performing the Ugi reaction with DMB-protected isocyanide gave access to either oxazoles or thiazol...
Scheme 40: Ugi/cyclization-approach towards 2,5-disubstituted thiazoles. The Ugi reaction was performed with d...
Scheme 41: Further derivatization of the thiazole scaffold.
Scheme 42: Three-step procedure towards the natural product bacillamide C.
Scheme 43: Ugi-4CR to oxazoles reported by Zhu and co-workers.
Scheme 44: Ugi-based synthesis of oxazole-containing peptidomimetics.
Scheme 45: TMNS3 based Ugi reaction for peptidomimics containing a tetrazole.
Scheme 46: Catalytic cycle of the enantioselective Passerini reaction towards tetrazole-based peptidomimetics.
Scheme 47: Tetrazole-based peptidomimetics via an Ugi reaction and a subsequent sigmatropic rearrangement.
Scheme 48: Resin-bound Ugi-approach towards tetrazole-based peptidomimetics.
Scheme 49: Ugi/cyclization approach towards γ/δ/ε-lactam tetrazoles.
Scheme 50: Ugi-3CR to pipecolic acid-based peptidomimetics.
Scheme 51: Staudinger–Aza-Wittig/Ugi-approach towards pipecolic acid peptidomimetics.
Figure 1: The three structural isomers of diketopiperazines. The 2,5-DKP isomer is most common.
Scheme 52: UDC-approach to obtain 2,5-DKPs, either using Armstrong’s isocyanide or via ethylglyoxalate.
Scheme 53: a) Ugi reaction in water gave either 2,5-DKP structures or spiro compounds. b) The Ugi reaction in ...
Scheme 54: Solid-phase approach towards diketopiperazines.
Scheme 55: UDAC-approach towards DKPs.
Scheme 56: The intermediate amide is activated as leaving group by acid and microwave assisted organic synthes...
Scheme 57: UDC-procedure towards active oxytocin inhibitors.
Scheme 58: An improved stereoselective MCR-approach towards the oxytocin inhibitor.
Scheme 59: The less common Ugi reaction towards DKPs, involving a Sn2-substitution.
Figure 2: Spatial similarities between a natural β-turn conformation and a DKP based β-turn mimetic [158].
Scheme 60: Ugi-based syntheses of bicyclic DKPs. The amine component is derived from a coupling between (R)-N-...
Scheme 61: Ugi-based synthesis of β-turn and γ-turn mimetics.
Figure 3: Isocyanide substituted 3,4-dihydropyridin-2-ones, dihydropyridines and the Freidinger lactams. Bio-...
Scheme 62: The mechanism of the 4-CR towards 3,4-dihydropyridine-2-ones 212.
Scheme 63: a) Multiple MCR-approach to provide DHP-peptidomimetic in two-steps. b) A one-pot 6-CR providing th...
Scheme 64: The MCR–alkylation–MCR procedure to obtain either tetrapeptoids or depsipeptides.
Scheme 65: U-3CR/cyclization employing semicarbazone as imine component gave triazine based peptidomimetics.
Scheme 66: 4CR towards triazinane-diones.
Scheme 67: The MCR–alkylation–IMCR-sequence described by our group towards triazinane dione-based peptidomimet...
Scheme 68: Ugi-4CR approaches followed by a cyclization to thiomorpholin-ones (a) and pyrrolidines (b).
Scheme 69: UDC-approach for benzodiazepinones.
Scheme 70: Ugi/Mitsunobu sequence to BDPs.
Scheme 71: A UDAC-approach to BDPs with convertible isocyanides. The corresponding amide is cleaved by microwa...
Scheme 72: microwave assisted post condensation Ugi reaction.
Scheme 73: Benzodiazepinones synthesized via the post-condensation Ugi/ Staudinger–Aza-Wittig cyclization.
Scheme 74: Two Ugi/cyclization approaches utilizing chiral carboxylic acids. Reaction (a) provided the product...
Scheme 75: The mechanism of the Gewald-3CR includes three base-catalysed steps involving first a Knoevnagel–Co...
Scheme 76: Two structural 1,4-thienodiazepine-2,5-dione isomers by U-4CR/cyclization.
Scheme 77: Tetrazole-based diazepinones by UDC-procedure.
Scheme 78: Tetrazole-based BDPs via a sequential Ugi/hydrolysis/coupling.
Scheme 79: MCR synthesis of three different tricyclic BPDs.
Scheme 80: Two similar approaches both involving an Ugi reaction and a Mitsunobu cyclization.
Scheme 81: Mitsunobu–Ugi-approach towards dihydro-1,4-benzoxazepines.
Scheme 82: Ugi reaction towards hetero-aryl fused 5-oxo-1,4-oxazepines.
Scheme 83: a) Ugi/RCM-approach towards nine-membered peptidomimetics b) Sequential peptide-coupling, deprotect...
Scheme 84: Ugi-based synthesis towards cyclic RGD-pentapeptides.
Scheme 85: Ugi/MCR-approach towards 12–15 membered macrocycles.
Scheme 86: Stereoselective Ugi/RCM approach towards 16-membered macrocycles.
Scheme 87: Passerini/RCM-sequence to 22-membered macrocycles.
Scheme 88: UDAC-approach towards 12–18-membered depsipeptides.
Figure 4: Enopeptin A with its more active derivative ADEP-4.
Scheme 89: a) The Joullié–Ugi-approach towards ADEP-4 derivatives b) Ugi-approach for the α,α-dimethylated der...
Scheme 90: Ugi–Click-strategy for 15-membered macrocyclic glyco-peptidomimetics.
Scheme 91: Ugi/Click combinations provided macrocycles containing both a triazole and an oxazole moiety.
Scheme 92: a) A solution-phase procedure towards macrocycles. b) Alternative solid-phase synthesis as was repo...
Scheme 93: Ugi/cyclization towards cyclophane based macrocycles.
Scheme 94: PADAM-strategy towards eurystatin A.
Scheme 95: PADAM-approach for cyclotheanamide.
Scheme 96: A triple MCR-approach affording RGD-pentapeptoids.
Scheme 97: Ugi-MiBs-approach towards peptoid macrocycles.
Scheme 98: Passerini-based MiB approaches towards macrocycles 345 and 346.
Scheme 99: Macrocyclic peptide formation by the use of amphoteric aziridine-based aldehydes.
The chemistry of bisallenes
- Henning Hopf and
- Georgios Markopoulos
Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225
- properties (polarity, solubility) strongly enough to allow easy separation/purification by chromatography and/or recrystallization. The different isomers 178–181 are interesting starting materials in cyclophane chemistry in their own right. Other asymmetrically substituted triple-bond dienophiles that have
Graphical Abstract
Figure 1: Loschmidt’s structure proposal for benzene (1) (Scheme 181 from [3]) and the corresponding modern stru...
Figure 2: The first isolated bisallenes.
Figure 3: Carbon skeletons of selected bisallenes discussed in this review.
Scheme 1: The preparation of 1,2,4,5-hexatetraene (2).
Scheme 2: The preparation of a conjugated bisallene by the DMS-protocol.
Scheme 3: Preparation of the 3-deuterio- and 3,4-dideuterio derivatives of 24.
Scheme 4: A versatile method to prepare alkylated conjugated bisallenes and other allenes.
Scheme 5: A preparation of 3,4-dimethyl-1,2,4,5-hexatetraene (38).
Scheme 6: A (C6 + 0)-approach to 1,2,4,5-hexatetraene (2).
Scheme 7: The preparation of a fully alkylated bisallenes from a 2,4-hexadiyne-1,6-diol diacetate.
Scheme 8: The preparation of the first phenyl-substituted conjugated bisallenes 3 and 4.
Scheme 9: Selective hydrogenation of [5]cumulenes to conjugated bisallenes: another (C6 + 0)-route.
Scheme 10: Aryl-substituted conjugated bisallenes by a (C3 + C3)-approach.
Scheme 11: Hexaphenyl-1,2,4,5-hexatetraene (59) by a (C3 + C3)-approach.
Scheme 12: An allenation route to conjugated bisallenes.
Scheme 13: The preparation of 3,4-difunctionalized conjugated bisallenes.
Scheme 14: Problems during the preparation of sulfur-substituted conjugated bisallenes.
Scheme 15: The preparation of 3,4-dibromo bisallenes.
Scheme 16: Generation of allenolates by an oxy-Cope rearrangement.
Scheme 17: A linear trimerization of alkynes to conjugated bisallenes: a (C2 + C2 + C2)-protocol.
Scheme 18: Preparation of a TMS-substituted conjugated bisallene by a C3-dimerization route.
Scheme 19: A bis(trimethylsilyl)bisallene by a C3-coupling protocol.
Scheme 20: The rearrangement of highly substituted benzene derivatives into their conjugated bisallenic isomer...
Scheme 21: From fully substituted benzene derivatives to fully substituted bisallenes.
Scheme 22: From a bicyclopropenyl to a conjugated bisallene derivative.
Scheme 23: The conversion of a bismethylenecyclobutene into a conjugated bisallene.
Scheme 24: The preparation of monofunctionalized bisallenes.
Scheme 25: Preparation of bisallene diols and their cyclization to dihydrofurans.
Scheme 26: A 3,4-difunctionalized conjugated bisallene by a C3-coupling process.
Scheme 27: Preparation of a bisallenic diketone by a coupling reaction.
Scheme 28: Sulfur and selenium-substituted bisallenes by a [2.3]sigmatropic rearrangement.
Scheme 29: The biallenylation of azetidinones.
Scheme 30: The preparation of a fully ferrocenylated conjugated bisallene.
Scheme 31: The first isomerization of a 1,5-hexadiyne to a 1,2,4,5-hexatetraene.
Scheme 32: The preparation of alkynyl-substituted bisallenes by a C3-dimerization protocol.
Scheme 33: Preparation of another completely ferrocenylated bisallene.
Scheme 34: The cyclization of 1,5-hexadiyne (129) to 3,4-bismethylenecyclobutene (130) via 1,2,4,5-hexatetraen...
Scheme 35: Stereochemistry of the thermal cyclization of bisallenes to bismethylenecyclobutenes.
Scheme 36: Bisallene→bismethylenecyclobutene ring closures in the solid state.
Scheme 37: A bisallene cyclization/dimerization reaction.
Scheme 38: A selection of Diels–Alder additions of 1,2,4,5-hexatetraene with various double-bond dienophiles.
Scheme 39: The stereochemistry of the [2 + 4] cycloaddition to conjugated bisallenes.
Scheme 40: Preparation of azetidinone derivatives from conjugated bisallenes.
Scheme 41: Cycloaddition of heterodienophiles to a conjugated bisallene.
Scheme 42: Addition of triple-bond dienophiles to conjugated bisallenes.
Scheme 43: Sulfur dioxide addition to conjugated bisallenes.
Scheme 44: The addition of a germylene to a conjugated bisallene.
Scheme 45: Trapping of conjugated bisallenes with phosphinidenes.
Scheme 46: The cyclopropanantion of 1,2,4,5-hexatetraene (2).
Scheme 47: Photochemical reactions involving conjugated bisallenes.
Scheme 48: Base-catalyzed isomerizations of conjugated bisallenes.
Scheme 49: Ionic additions to a conjugated bisallene.
Scheme 50: Oxidation reactions of a conjugated bisallene.
Scheme 51: The mechanism of oxidation of the bisallene 24.
Scheme 52: CuCl-catalyzed cyclization of 1,2,4,5-hexatetraene (2).
Scheme 53: The conversion of conjugated bisallenes into cyclopentenones.
Scheme 54: Oligomerization of a conjugated bisallene by nickel catalysts.
Scheme 55: Generation of 1,2,5,6-heptatetraene (229) as a reaction intermediate.
Scheme 56: The preparation of a stable derivative of 1,2,5,6-heptatetraene.
Scheme 57: A bisallene with a carbonyl group as a spacer element.
Scheme 58: The first preparation of 1,2,6,7-octatetraene (242).
Scheme 59: Preparation of 1,2,6,7-octatetraenes by (C4 + C4)-coupling of enynes.
Scheme 60: Preparation of 1,2,6,7-octatetraenes by (C4 + C4)-coupling of homoallenyl bromides.
Scheme 61: Preparation of 1,2,6,7-octatetraenes by alkylation of propargylic substrates.
Scheme 62: Preparation of two highly functionalized 1,2,6,7-octatetraenes.
Scheme 63: Preparation of several higher α,ω-bisallenes.
Scheme 64: Preparation of different alkyl derivatives of α,ω-bisallenes.
Scheme 65: The preparation of functionalized 1,2,7,8-nonatetraene derivatives.
Scheme 66: Preparation of functionalized α,ω-bisallenes.
Scheme 67: The preparation of an α,ω-bisallene by direct homologation of an α,ω-bisalkyne.
Scheme 68: The gas-phase pyrolysis of 4,4-dimethyl-1,2,5,6-heptatetraene (237).
Scheme 69: Gas-phase pyrolysis of 1,2,6,7-octatetraene (242).
Scheme 70: The cyclopropanation of 1,2,6,7-octatetraene (242).
Scheme 71: Intramolecular cyclization of 1,2,6,7-octatetraene derivatives.
Scheme 72: The gas-phase pyrolysis of 1,2,7,8-nonatetraene (265) and 1,2,8,9-decatetraene (266).
Scheme 73: Rh-catalyzed cyclization of a functionalized 1,2,7,8-nonatetraene.
Scheme 74: A triple cyclization involving two different allenic substrates.
Scheme 75: Bicyclization of keto derivatives of 1,2,7,8-nonatetraene.
Scheme 76: The preparation of complex organic compounds from functionalized bisallenes.
Scheme 77: Cycloisomerization of an α,ω-bisallene containing a C9 tether.
Scheme 78: Organoborane polymers from α,ω-bisallenes.
Scheme 79: Preparation of trans- (337) and cis-1,2,4,6,7-octapentaene (341).
Scheme 80: The preparation of 4-methylene-1,2,5,6-heptatetraene (349).
Scheme 81: The preparation of acetylenic bisallenes.
Scheme 82: The preparation of derivatives of hydrocarbon 351.
Scheme 83: The construction of macrocyclic alleno-acetylenes.
Scheme 84: Preparation and reactions of 4,5-bismethylene-1,2,6,7-octatetraene (365).
Scheme 85: Preparation of 1,2-bis(propadienyl)benzene (370).
Scheme 86: The preparation of 1,4-bis(propadienyl)benzene (376).
Scheme 87: The preparation of aromatic and heteroaromatic bisallenes by metal-mediated coupling reactions.
Scheme 88: Double cyclization of an aromatic bisallene.
Scheme 89: Preparation of an allenic [15]paracyclophane by a ring-closing metathesis reaction of an aromatic α...
Scheme 90: Preparation of a macrocyclic ring system containing 1,4-bis(propadienyl)benzene units.
Scheme 91: Preparation of copolymers from 1,4-bis(propadienyl)benzene (376).
Scheme 92: A boration/copolymerization sequence of an aromatic bisallene and an aromatic bisacetylene.
Scheme 93: Formation of a layered aromatic bisallene.
Figure 4: The first members of the semicyclic bisallene series.
Scheme 94: Preparation of the first bis(vinylidene)cyclobutane derivative.
Scheme 95: Dimerization of strain-activated cumulenes to bis(vinylidene)cyclobutanes.
Scheme 96: Photodimerization of two fully substituted butatrienes in the solid state.
Scheme 97: Preparation of the two parent bis(vinylidene)cyclobutanes.
Scheme 98: The preparation of 1,3-bis(vinylidene)cyclopentane and its thermal isomerization.
Scheme 99: The preparation of the isomeric bis(vinylidene)cyclohexanes.
Scheme 100: Bi- and tricyclic conjugated bisallenes.
Scheme 101: A selection of polycyclic bisallenes.
Scheme 102: The first endocyclic bisallenes.
Figure 5: The stereochemistry of 1,2,6,7-cyclodecatetraene.
Scheme 103: The preparation of several endocyclic bisallenes.
Scheme 104: Synthesis of diastereomeric derivatives of 1,2,6,7-cyclodecatetraene.
Scheme 105: Preparation of a derivative of 1,2,8,9-cyclotetradecatetraene.
Scheme 106: The preparation of keto derivatives of cyclic bisallenes.
Scheme 107: The preparation of cyclic biscumulenic ring systems.
Scheme 108: Cyclic bisallenes in natural- and non-natural-product chemistry.
Scheme 109: The preparation of iron carbonyl complexes from cyclic bisallenes.
Figure 6: A selection of unknown exocyclic bisallenes that should have interesting chemical properties.
Scheme 110: The thermal isomerization of 1,2-diethynylcyclopropanes and -cyclobutanes.
Scheme 111: Intermediate generation of a cyclooctapentaene.
Scheme 112: Attempted preparation of a cyclodecahexaene.
Scheme 113: The thermal isomerization of 1,5,9-cyclododecatriyne (511) into [6]radialene (514).
Scheme 114: An isomerization involving a diketone derived from a conjugated bisallene.
Scheme 115: Typical reaction modes of heteroorganic bisallenes.
Scheme 116: Generation and thermal behavior of acyclic hetero-organic bisallenes.
Scheme 117: Generation of bis(propadienyl)thioether.
Scheme 118: The preparation of a bisallenic sulfone and its thermal isomerization.
Scheme 119: Bromination of the bisallenic sulfone 535.
Scheme 120: Metalation/hydrolysis of the bisallenic sulfone 535.
Scheme 121: Aromatic compounds from hetero bisallenes.
Scheme 122: Isomerization/cyclization of bispropargylic ethers.
Scheme 123: The preparation of novel aromatic systems by base-catalyzed isomerization of bispropargyl ethers.
Scheme 124: The isomerization of bisacetylenic thioethers to bicyclic thiophenes.
Scheme 125: Aromatization of macrocyclic bispropargylic sulfides.
Scheme 126: Preparation of ansa-compounds from macrocyclic bispropargyl thioethers.
Scheme 127: Alternate route for cyclization of a heterorganic bisallene.
Scheme 128: Multiple isomerization/cyclization of “double” bispropargylic thioethers.
Scheme 129: Preparation of a bisallenyl disulfide and its subsequent bicyclization.
Scheme 130: Thermal cyclization of a bisallenyl thiosulfonate.
Scheme 131: Some reactions of heteroorganic bisallenes with two sulfur atoms.
Scheme 132: Further methods for the preparation of heteroorganic bisallenes.
Scheme 133: Cyclization reactions of heteroorganic bisallenes.
Scheme 134: Thermal cycloadditions of bisallenic tertiary amines.
Scheme 135: Cyclization of a bisallenic tertiary amine in the presence of a transition-metal catalyst.
Scheme 136: A Pauson–Khand reaction of a bisallenic ether.
Scheme 137: Formation of a 2:1adduct from two allenic substrates.
Scheme 138: A ring-forming silastannylation of a bisallenic tertiary amine.
Scheme 139: A three-component cyclization involving a heterorganic bisallene.
Scheme 140: Atom-economic construction of a complex organic framework from a heterorganic α,ω-bisallene.
Photoreactions of cyclic sulfite esters: Evidence for diradical intermediates
- Rick C. White,
- Benny E. Arney Jr. and
- Heiko Ihmels
Beilstein J. Org. Chem. 2012, 8, 1208–1212, doi:10.3762/bjoc.8.134
- -containing functionalities are rather rare. For instance, the photoextrusion of sulfur dioxide was carried out to facilitate the preparation of cyclophane derivatives [15]. The photochemistry of the corresponding cyclic sulfite esters is even less well known [16][17][18]. A report on the photochemistry of
Graphical Abstract
Scheme 1: Photolysis of cyclic carbonate esters 1a and 1b in acetonitrile.
Scheme 2: Photoreactivity of styrene glycol sulfite (8).
Scheme 3: Photochemical pathway for photoextrusion of SO2 from cyclic sulfites.
Scheme 4: Photoreactivity of meso-hydrobenzoin sulfite (9).
Control over molecular motion using the cis–trans photoisomerization of the azo group
- Estíbaliz Merino and
- María Ribagorda
Beilstein J. Org. Chem. 2012, 8, 1071–1090, doi:10.3762/bjoc.8.119
- used light intensity [112][113][114]. Molecular threader Stoddart, Balzani et al. [115][116] created an intelligent molecular device (trans-10∙11) capable of moving within a cyclophane 11, as a needle through a buttonhole (Figure 12). The interaction between the two systems is measured on the
- fluorescence emitted by the pyridinium salt free cyclophane. The azobenzene trans-10 is conveniently replaced with electron donor units, so that when it is associated, as azo-10∙11, the fluorescence is completely inhibited by charge-transfer interactions. The photoexcitation carried out by irradiation with
- light of λ = 360 nm of a solution of trans-10 and 11 causes a process of “unthreading”. The cis isomer 10 has a much weaker interaction with cyclophane 11, and this fact is reflected in the large increase in fluorescence intensity of 11. The trans-isomer 10 is regenerated when the mixture is left in the
Graphical Abstract
Figure 1: Photoisomerization process of azobenzene.
Figure 2: Representative example of an UV spectrum of an azocompound of the azobenzene type (blue line: trans...
Figure 3: Mechanistic proposals for the isomerization of azobenzenes.
Figure 4: Representation of the photocontrol of a K+ channel in the cellular membrane based on the isomerizat...
Figure 5: (a) MAG interaction with iGluR; (b) photocontrol of the opening of the ion channel by trans–cis iso...
Figure 6: Photocontrol of the structure of the α-helix in the polypeptide azoderivative 2. Reprinted (adapted...
Figure 7: Recognition of a guanidinium ion by a cis,cis-bis-azo derivative 3.
Figure 8: Recognition of cesium ions by cis-azo derivative 4.
Figure 9: Photocontrolled formation of an inclusion complex of cyclodextrin trans-azo 5+6.
Figure 10: Pseudorotaxane-based molecular machine.
Figure 11: Molecular hinge. Reprinted (adapted) with permission from Org. Lett. 2004, 6, 2595–2598. Copyright ...
Figure 12: Molecular threader. Reprinted (adapted) with permission from Acc. Chem. Res. 2001, 34, 445–455. Cop...
Figure 13: Molecular scissors based on azobenzene 12. Reprinted (adapted) with permission from J. Am. Chem. So...
Figure 14: Molecular pedals. Reprinted by permission from Macmillan Publishers Ltd: Nature, 2006, 440, 512–515...
Figure 15: Design of nanovehicles based on azo structures. Reprinted (adapted) with permission from Org. Lett. ...
Figure 16: Light-activated mesostructured silica nanoparticles (LAMs).
Figure 17: Molecular lift.
Figure 18: Conformational considerations in mono-ortho-substituted azobenzenes.
Scheme 1: Synthesis and photoisomerization of sulfinyl azobenzenes. Reprinted (adapted) with permission from ...
Figure 19: Photoisomerization of azocompound 22 and its application as a photobase catalyst.
Figure 20: Effect of irradiation with linearly polarized light on azo-LCEs. Reprinted by permission from Macmi...
Figure 21: Chemically and photochemically triggered memory switching cycle of the [2]rotaxane 25.
Figure 22: Unidirectional photoisomerization process of the azobenzene 26.
