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Search for "alkali metals" in Full Text gives 18 result(s) in Beilstein Journal of Organic Chemistry.
Tying a knot between crown ethers and porphyrins
- Maksym Matviyishyn and
- Bartosz Szyszko
Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120
- alkali metals. Due to the presence of crown ether moieties, the receptors exhibited selective binding of K+, NH4+, and Ba2+. The pronounced changes in the absorption spectra of free-base ligands 1 and TriCP with adding K+, NH4+, and Ba2+ cations were observed, whereas Na+, Mg2+, and Ca2+ did not produce
Graphical Abstract
Figure 1: Porphyrin and crown ether.
Figure 2: Timeline demonstrating the contributions into the crown ether–porphyrin chemistry.
Figure 3: Tetra-crowned porphyrin 1 and dimer 2 formed upon K+ binding.
Figure 4: meso-Crowned 25-oxasmaragdyrins 3a–c and their boron(III) complexes (3a–c)-BF2.
Scheme 1: CsF ion-pair binding of 4. The molecular structure of 4-CsF is shown on the right [101].
Figure 5: CsF ion pair binding by 5. The molecular structure of 5-CsF is shown on the right [102].
Scheme 2: Ion-pair binding by 6. The molecular structure of (6-CsCl)2 is shown on the right [103].
Scheme 3: Hydrated fluoride binding by 7 [104].
Figure 6: β-Crowned porphyrin 8.
Figure 7: Crown ether-capped porphyrins 9.
Figure 8: The capped porphyrin 10 and complex [10-PQ](PF6)2.
Figure 9: The double-capped porphyrin 11.
Figure 10: Selected examples of iminoporphyrinoids [58,122].
Scheme 4: The synthesis of 13.
Scheme 5: Tripyrrane-based crown ether-embedding porphyrinoid 15.
Figure 11: Macrocycles 16–19 and their coordination compounds.
Scheme 6: The flexibility of 16-Co [66].
Figure 12: Hexagonal wheel composed of six 16-Co(III) monomers [66].
Scheme 7: The synthesis of 16-V [67].
Figure 13: The molecular structure of dimers [16-Mn]2 [67].
Scheme 8: Synthesis of crownphyrins 28–33. Compounds 23a/b and 29a/b were obtained from 4,7,10-trioxa-1,13-tr...
Figure 14: The molecular structures of 22a, 34a·(HCl)2, and 29b [69].
Figure 15: Molecular structures of 22a-Pb and (29b)2-Zn [69].
Scheme 9: Reactivity of 29a/b.
Scheme 10: Synthesis of 36 and 37 [131].
Scheme 11: Synthesis of 40–45.
Figure 16: Potential applications of porphyrin-crown ether hybrids.
Photoredox catalysis harvesting multiple photon or electrochemical energies
- Mattia Lepori,
- Simon Schmid and
- Joshua P. Barham
Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81
- half potential (*E1/2 = −3.36 V vs SCE) even more negative than alkali metals including lithium, making it one of the most potent chemical reductants ever reported. Owing to this exceptional reductive redox power, hydrodehalogenation of various electron-poor and electron-rich aryl bromides and
Graphical Abstract
Figure 1: Oxidative and reductive activations of organic compounds harvesting photoredox catalysis.
Figure 2: General catalytic cycles of radical ion conPET (left) and radical ion e-PRC (right).
Figure 3: “Beginner’s guide”: comparison between advantages, capacities, and prospectives of conPET and PEC.
Figure 4: A) conPET reductive dehalogenation of aryl halides with PDI. B) Reductive C–H arylation with pyrrol...
Figure 5: A) Chromoselective mono- and disubstitution or polybrominated pyrimidines with pyrroles. B) Sequent...
Figure 6: A) Synthesis of pyrrolo[1,2-a]quinolines. B) Synthesis of ullazines.
Figure 7: A) Reductive phosphorylation of aryl halides via conPET. B) Selected examples from the substrate sc...
Figure 8: A) Reductive dehalogenation of aryl halides via conPET and selected examples from the substrate sco...
Figure 9: A) Reductive C–H arylation of aryl halides via conPET (top) and selected examples from the substrat...
Figure 10: A) Reductive hydrodehalogenation of aryl halides with Mes-Acr-BF4. B) Selected examples from the su...
Figure 11: A) Reductive hydrodechlorination of aryl chlorides with 4-DPAIPN. B) Proposed formation of CO2•−. C...
Figure 12: A) Reductive conPET borylation with 3CzEPAIPN (top) and selected examples from the substrate scope ...
Figure 13: Scale-up of conPET phosphorylation with 3CzEPAIPN.
Figure 14: A) Borylation of 1d. B) Characteristics and structure of PC1 with green and red parts showing the l...
Figure 15: A) Reductive C–H arylation scope with polysulfide conPET (top) and selected examples from the subst...
Figure 16: Scale-up of A) C–H arylation and B) dehaloborylation with polysulfide photocatalysis in continuous-...
Figure 17: A) Formation of [Ir1]0 and [Ir2]0 upon PET between [Ir1]+ and Et3N. B) Mechanism of multi-photon ta...
Figure 18: A) Reductive hydrodehalogenation of aryl halides via multi-photon tandem photocatalysis. B) Selecte...
Figure 19: A) Carbonylative amidation of aryl halides in continuous flow. B) Selected examples from the substr...
Figure 20: A) General scheme for reductive (RQ) and oxidative quenching (OQ) protocols using [FeIII(btz)3](PF6)...
Figure 21: A) Carbonylative amidation of alkyl iodides with [IrIII(ppy)2(dtbbpy)]PF6. B) Selected examples fro...
Figure 22: A) Carboxylative C–N bond cleavage in cyclic amines. B) Selected examples from the substrate scope....
Figure 23: A) Formal reduction of alkenes to alkanes via transfer hydrogenation. B) Selected examples from the...
Figure 24: A) Birch-type reduction of benzenes with PMP-BPI. B) Selected examples from the substrate scope (sc...
Figure 25: Proposed mechanism of the OH− mediated conPET Birch-type reduction of benzene via generation of sol...
Figure 26: Reductive detosylation of N-tosylated amides with Mes-Acr-BF4. B) Selected examples from the substr...
Figure 27: A) Reductive detosylation of N-tosyl amides by dual PRC. B) Selected examples from the substrate sc...
Figure 28: A) Mechanism of the dual PRC based on PET between [Cu(dap)2]+ and DCA. B) Mechanism of the dual PRC...
Figure 29: A) N–O bond cleavage in Weinreb amides with anthracene. B) N–O bond cleavage in Weinreb amides rely...
Figure 30: A) Pentafluorosulfanylation and fluoride elimination. B) Mechanism of the pentafluorosulfanylation ...
Figure 31: A) α-Alkoxypentafluorosulfanylation (top) and selected examples from the substrate scope (bottom). ...
Figure 32: A) Oxidative amination of arenes with azoles catalyzed by N-Ph PTZ. B) Selected examples from the s...
Figure 33: A) C(sp3)–H bond activation by HAT via chloride oxidation by *N-Ph PTZ•+. B) Proposed mechanism for...
Figure 34: A) Recycling e-PRC C–H azolation of electron-rich arenes with pyrazoles using Mes-Acr+ as a photoca...
Figure 35: A) Radical ion e-PRC direct oxidation of unactivated arenes using TAC+ as an electro-activated phot...
Figure 36: A) Radical ion e-PRC direct oxidation of unactivated arenes using TPA as an electro-activated photo...
Figure 37: Proposed mechanism (top) and mode of preassembly (bottom).
Figure 38: A) Possible preassemblies of reactive (left) vs unreactive (right) arenes. B) Calculated spin densi...
Figure 39: A) Recycling e-PRC C(sp2 )–H acetoxylation of arenes using DDQ as a photocatalyst. B) Proposed cata...
Figure 40: Gram scale hydroxylation of benzene in a recirculated flow setup.
Figure 41: A) Radical ion e-PRC vicinal diamination of alkylarenes using TAC+ as an electro-activated photocat...
Figure 42: A) Sequential oxygenation of multiple adjacent C–H bonds under radical ion e-PRC using TAC+ as an e...
Figure 43: A) Enantioselective recycling e-PRC cyanation of benzylic C–H bonds using ADQS as photocatalyst. B)...
Figure 44: Proposed tandem mechanism by Xu and co-workers.
Figure 45: A) Enantioselective recycling e-PRC decarboxylative cyanation using Cu(acac)2, Ce(OTf)3 and a box l...
Figure 46: A) Enantioselective recycling e-PRC benzylic cyanation using Cu(MeCN)4BF4, box ligand and anthraqui...
Figure 47: A) Radical ion e-PRC acetoxyhydroxylation of aryl olefins using TAC+ as an electro-activated photoc...
Figure 48: Selected examples from the substrate scope.
Figure 49: Photoelectrochemical acetoxyhydroxylation in a recirculated flow setup.
Figure 50: A) Radical ion e-PRC aminooxygenation of aryl olefins using TAC+ as an electro-activated photocatal...
Figure 51: A) Recycling e-PRC C–H alkylation of heteroarenes with organic trifluoroborates using Mes-Acr+ as p...
Figure 52: A) Recycling e-PRC decarboxylative C–H alkylation of heteroarenes using CeCl3·7H2O as catalyst. B) ...
Figure 53: A) Recycling e-PRC decarboxylative C–H alkylation of heteroarenes using Fe(NH4)2(SO4)2·6H2O as cata...
Figure 54: A) Recycling e-PRC C–H alkylation of heteroarenes with alkyl oxalates and 4CzIPN as photocatalyst. ...
Figure 55: A) Recycling e-PRC decarboxylative C–H carbamoylation of heteroarenes using 4CzIPN as photocatalyst...
Figure 56: A) Photoelectrochemical HAT-mediated hydrocarbon activation via the chlorine radical. B) Proposed m...
Figure 57: A) Selected examples from the substrate scope. B) Gram and decagram scale semi-continuous flow PEC ...
Figure 58: A) Photoelectrochemical HAT-mediated dehydrogenative coupling of benzothiazoles with aliphatic C–H ...
Figure 59: A) Photoelectrochemical HAT activation of ethers using electro-activated TAC+ as photocatalyst. B) ...
Figure 60: Selected examples from the substrate scope.
Figure 61: A) Photoelectrochemical HAT-mediated synthesis of alkylated benzimidazo-fused isoquinolinones using...
Figure 62: A) Decoupled photoelectrochemical cerium-catalyzed oxydichlorination of alkynes using CeCl3 as cata...
Figure 63: Proposed decoupled photoelectrochemical mechanism.
Figure 64: A) Decoupled photoelectrochemical ring-opening bromination of tertiary cycloalkanols using MgBr2 as...
Figure 65: A) Recycling e-PRC ring-opening functionalization of cycloalkanols using CeCl3 as catalyst. B) Prop...
Figure 66: Selected examples from the substrate scope of the PEC ring-opening functionalization.
Figure 67: A) Radical ion e-PRC reduction of chloro- and bromoarenes using DCA as catalyst and various accepto...
Figure 68: A) Screening of different phthalimide derivatives as catalyst for the e-PRC reduction of aryl halid...
Figure 69: Screening of different organic catalysts for the e-PRC reduction of trialkylanilium salts.
Figure 70: A) e-PRC reduction of phosphonated phenols and anilinium salts. B) Selected examples from the subst...
Figure 71: A) ConPET and e-PRC reduction of 4-bromobenzonitrile using a naphthalene diimide (NDI) precatalyst ...
Figure 72: A) Radical ion e-PRC reduction of phosphinated aliphatic alcohols with n-BuO-NpMI as catalyst. B) C...
Figure 73: Selected examples from the substrate scope.
Figure 74: A) Recycling e-PRC reductive dimerization of benzylic chlorides using a [Cu2] catalyst. B) Proposed...
Figure 75: A) Decoupled photoelectrochemical C–H alkylation of heteroarenes through deamination of Katritzky s...
Figure 76: Proposed mechanism by Chen and co-workers.
Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis
- Prodip Howlader and
- Michael Schmittel
Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62
- the electrostatic interaction of crown ethers and alkali metals [4]. While, in the beginning, crown ethers were an excellent choice for metal ion complexation, they later received ample recognition as supramolecular catalysts [49]. The majority of host capsules, however, has been constructed using
Graphical Abstract
Figure 1: Butterfly 1 (Figure was reprinted with permission from [45]. Copyright 2012 American Chemical Society. ...
Figure 2: Synthesis of the three-component heteroleptic molecular boat 8 and its use as a catalyst for the Kn...
Figure 3: Synthesis of the two-component triangle 14 and three-component heteroleptic prism 15 [59]. Figure was a...
Figure 4: Catalytic Michael addition reaction using the urea-decorated molecular prism 15 [59].
Figure 5: Self-assembly of two-component tetragonal prismatic architectures with different cavity size. Figur...
Figure 6: Construction of artificial LHS using rhodamine B as an acceptor and 24b as donor generating a photo...
Figure 7: Synthesis of supramolecular spheres with varying [AuCl] concentration inside the cavity. Figure was...
Figure 8: Hydroalkoxylation reaction of γ-allenol 34 in the presence of [AuCl]-encapsulated molecular spheres ...
Figure 9: Two-component heteroleptic triangles of different size containing a BINOL functionality. Figure was...
Figure 10: Asymmetric conjugate addition of chalcone 42 with trans-styrylboronic acid (43) catalyzed by BINOL-...
Figure 11: Encapsulation of monophosphoramidite-Rh(I) catalyst into a heteroleptic tetragonal prismatic cage 47...
Figure 12: (a) Representations of the basic HETPYP, HETPHEN, and HETTAP complex motifs. (b) The three-componen...
Figure 13: Two representative four-component rotors, with a (top) two-arm stator and (bottom) a four-arm stato...
Figure 14: Four-component rotors with a monohead rotator. Figure was adapted with permission from [94]. Copyright ...
Figure 15: (left) Click reaction catalyzed by rotors [Cu2(55)(60)(X)]2+. (right) Yield as a function of the ro...
Figure 16: A supramolecular AND gate. a) In truth table state (0,0) two nanoswitches serve as the receptor ens...
Figure 17: Two supramolecular double rotors (each has two rotational axes) and reference complex [Cu(78)]+ for...
Figure 18: The slider-on-deck system (82•X) (X = 83, 84, or 85). Figure is from [98] and was reprinted from the jo...
Figure 19: Catalysis of a conjugated addition reaction in the presence of the slider-on-deck system (82•X) (X ...
Figure 20: A rotating catalyst builds a catalytic machinery. For catalysis of the catalytic machinery, see Figure 21. F...
Figure 21: Catalytic machinery. Figure was adapted from [100] (“Evolution of catalytic machinery: three-component n...
Figure 22: An information system based on (re)shuffling components between supramolecular structures [99]. Figure ...
Figure 23: Switching between dimeric heteroleptic and homoleptic complex for OFF/ON catalytic formation of rot...
Figure 24: A chemically fueled catalytic system [112]. Figure was adapted from [112]. Copyright 2021 American Chemical S...
Figure 25: (Top) Operation of a fuel acid. (Bottom) Knoevenagel addition [112].
Figure 26: Development of the yield of Knoevenagel product 118 in a fueled system [112]. Figure was reprinted with ...
Figure 27: Weak-link strategy to increased catalytic activity in epoxide opening [119]. Figure was adapted from [24]. C...
Figure 28: A ON/OFF polymerization switch based on the weak-link approach [118]. Figure was reprinted with permissi...
Figure 29: A weak-link switch turning ON/OFF a Diels–Alder reaction [132]. Figure was reprinted with permission fro...
Figure 30: A catalyst duo allowing selective activation of one of two catalytic acylation reactions [133] upon subs...
Figure 31: A four-state switchable nanoswitch (redrawn from [134]).
Figure 32: Sequential catalysis as regulated by nanoswitch 138 and catalyst 139 in the presence of metal ions ...
Figure 33: Remote control of ON/OFF catalysis administrated by two nanoswitches through ion signaling (redrawn...
Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186
Graphical Abstract
Figure 1: Representation of corannulene (1) and sumanene (2), the subunits of fullerene (C60).
Scheme 1: Mehta’s unsuccessful effort for the synthesis of sumanene scaffold 2.
Scheme 2: First synthesis of sumanene 2 by Sakurai et al. from norbornadiene 10.
Scheme 3: Synthesis of trimethylsumanene 28 from easily accessible norbornadiene (10).
Scheme 4: Generation of anions 29–31 and the preparation of tris(trimethylsilyl)sumanene 32.
Scheme 5: Synthesis of tri- and hexa-substituted sumanene derivatives.
Scheme 6: Synthesis of bowl-shaped π-extended sumanene derivatives 37a–f.
Scheme 7: Synthesis of monooxasumanene 38, trioxosumanene 40 along with imination of them.
Scheme 8: Synthesis of trimethylsumanenetrione 46 and exo-functionalized products 45a,b.
Scheme 9: Synthesis of bisumanenylidene 47 and sumanene dimer 48 from 2.
Scheme 10: The mono-substitution of 2 to generate diverse mono-sumanene derivatives 49a–d.
Scheme 11: Synthesis of sumanene building block 53 useful for further extension.
Scheme 12: Synthesis of hexafluorosumanene derivative 55 by Sakurai and co-workers.
Scheme 13: Preparation of sumanene-based carbene 60 and its reaction with cyclohexane.
Scheme 14: Barton–Kellogg reaction for the synthesis of sterically hindered alkenes.
Scheme 15: Synthesis of hydroxysumanene 68 by employing Baeyer–Villiger oxidation.
Scheme 16: Synthesis of sumanene derivatives having functionality at an internal carbon.
Scheme 17: Mechanism for nucleophilic substitution reaction at the internal carbon.
Scheme 18: Synthesis of diverse monosubstituted sumanene derivatives.
Scheme 19: Synthesis of di- and trisubstituted sumanene derivatives from sumanene (2).
Scheme 20: Preparation of monochlorosumanene 88 and hydrogenation of sumanene (2).
Scheme 21: The dimer 90 and bissumanenyl 92 achieved from halosumannes.
Scheme 22: Pyrenylsumanene 93 involving the Suzuki-coupling as a key transformation.
Scheme 23: Synthesis of various hexaarylsumanene derivatives using the Suzuki-coupling reaction.
Scheme 24: Synthesis of hexasubstituted sumanene derivatives 96 and 97.
Scheme 25: Synthesis of thioalkylsumanenes via an aromatic nucleophilic substitution reaction.
Scheme 26: Synthesis of tris(ethoxycarbonylethenyl)sumanene derivative 108.
Scheme 27: Synthesis of ferrocenyl-based sumanene derivatives.
Scheme 28: Synthesis of sumanenylferrocene architectures 118 and 119 via Negishi coupling.
Scheme 29: Diosmylation and the synthesis of phenylboronate ester 121 of sumanene.
Scheme 30: Synthesis of the iron-complex of sumanene.
Scheme 31: Synthesis of tri- and mononuclear sumanenyl zirconocene complexes.
Scheme 32: Synthesis of [CpRu(η6-sumanene)]PF6.
Scheme 33: Preparation of sumanene-based porous coordination networks 127 (spherical tetramer units) and 128 (...
Scheme 34: Synthesis of sumanenylhafnocene complexes 129 and 130.
Scheme 35: Synthesis of 134 and 135 along with PdII coordination complex 136.
Scheme 36: Synthesis of alkali metals sumanene complex K7(C21H102−)2(C21H93−)·8THF (137) containing di- and tr...
Scheme 37: The encapsulation of a Cs+ ion between two sumanenyl anions.
Scheme 38: Synthesis of monothiasumanene 140 and dithiasumanene 141 from 139.
Scheme 39: Synthesis of trithiasumanene 151 by Otsubo and his co-workers.
Scheme 40: Synthesis of trithiasumanene derivatives 155 and 156.
Scheme 41: Synthetic route towards hexathiolated trithiasumanenes 158.
Scheme 42: Synthesis of triselenasumanene 160 by Shao and teammates.
Scheme 43: Synthesis of tritellurasumanene derivatives from triphenylene skeletons.
Scheme 44: Synthesis of pyrazine-fused sumanene architectures through condensation reaction.
Scheme 45: Treatment of the trichalcogenasumanenes with diverse oxidative reagents.
Scheme 46: Ring-opening reaction with H2O2 and oxone of heterasumanenes 178 and 179.
Scheme 47: Synthesis of polycyclic compounds from sumanene derivatives.
Scheme 48: Synthesis of diimide-based heterocycles reported by Shao’s and co-workers.
Scheme 49: Synthesis of pristine trichalcogenasumanenes, 151, 205, and 206.
Scheme 50: Synthesis of trichalcogenasumanenes via hexaiodotriphenylene precursor 208.
Scheme 51: Synthesis of trisilasumanenes 214 and 215.
Scheme 52: Synthesis of trisilasumanene derivatives 218 and 219.
Scheme 53: Synthesis of novel trigermasumanene derivative 223.
Scheme 54: An attempt towards the synthesis of tristannasumanene derivative 228.
Scheme 55: Synthesis of triphosphasumanene trisulfide 232 from commercially available 229.
Scheme 56: The doping of sumanene derivatives with chalcogens (S, Se, Te) and phosphorus.
Scheme 57: Synthesis of heterasumanene containing three different heteroatoms.
Scheme 58: Synthesis of trichalcogenasumanene derivatives 240 and 179.
Scheme 59: Preparation of trichalcogenasumanenes 245 and 248.
Scheme 60: Design and synthesis of trichalcogenasumanene derivatives 252 and 178.
Scheme 61: Synthesis of spirosumanenes 264–269 and non-spiroheterasumanenes 258–263.
Scheme 62: Synthesis of sumanene-type hetero polycyclic compounds.
Scheme 63: Synthesis of triazasumanenes 288 and its sulfone congener 287.
Scheme 64: Synthesis of C3-symmetric chiral triaryltriazasumanenes via cross-coupling reaction.
Scheme 65: Synthesis of mononaphthosumanene 293 using Suzuki coupling as a key step.
Scheme 66: Synthesis of di- and trinaphthosumanene derivatives 302–304.
Scheme 67: Synthesis of hemifullerene skeletons by Hirao’s group.
Scheme 68: Design and construction of C70 fragment from a C60 sumanene fragment.
Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex
- Ross F. Koby,
- Nicholas R. Rightmire,
- Nathan D. Schley,
- Timothy P. Hanusa and
- William W. Brennessel
Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181
- difficult, and the extent of even partial exchange is hard to predict. For the alkali metals, all electronegativity scales indicate that caesium is the most electropositive, but they also indicate that there is comparatively little variation in this metric [12]. What happens when the energy difference
- concerns place limits on the combinations of halides and alkali metals that could be feasibly studied in intra-alkali exchange experiments. For example, the fluorides have the largest heats of formation of the alkali halides, regardless of metal, but their high lattice energies make them typically
Graphical Abstract
Figure 1: Portion of the polymeric chain of [CsKA'2], with thermal ellipsoids drawn at the 50% level. Hydroge...
Figure 2: Partial packing diagram of [CsKA'2], illustrating some of the interchain contacts, predominantly K1…...
Figure 3: Portion of the polymeric chain of [(C6H6)KA']∞, with thermal ellipsoids drawn at the 50% level. Hyd...
Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions
- László Jicsinszky,
- Federica Calsolaro,
- Katia Martina,
- Fabio Bucciol,
- Maela Manzoli and
- Giancarlo Cravotto
Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145
- the CD OH groups. The formation of CD alkali salts always results in residual water when no metals or metal hydrides are used. The safer use of the hydroxides, in comparison with alkali metals or their hydrides, considerably outweighs the purification costs. Scheme 1 shows a general reaction scheme
Graphical Abstract
Scheme 1: The reaction of CDs with oxiranes.
Figure 1: Jar-temperature changes during the reaction of 1,2-propylene oxide and cyclodextrins in the presenc...
Figure 2: Comparative SEM pictures of a β-CD bead and β-CDP (20 mmol, Table 3, entry 10).
Figure 3: Comparison of β-CDP (Table 3, entry 9) and γ-CDP (Table 3, entry 12) prepared in a ball mill on 2 mmol scale.
Figure 4: Normalised particle-size distribution of insoluble CD polymers (entries 9, 10, and 12 of Table 3).
Figure 5: UV–vis spectra and adsorption isotherm of the insoluble β-CDP polymer in 10 ml 0.050 mM MO solution...
Figure 6: UV–vis spectral changes of 0.050 mM MO solution by GPTS-β-CD (left) and GPTS-γ-CD (right), as prepa...
Figure 7: UV–vis spectral changes of 0.050 mM MO solution by GPTS-β-CD (left) and GPTS-γ-CD (right), as prepa...
Reactions of 3-(p-substituted-phenyl)-5-chloromethyl-1,2,4-oxadiazoles with KCN leading to acetonitriles and alkanes via a non-reductive decyanation pathway
- Akın Sağırlı and
- Yaşar Dürüst
Beilstein J. Org. Chem. 2018, 14, 3011–3017, doi:10.3762/bjoc.14.280
- ], transition metal complexes [25], and alkali metals in a variety of solvents [26]. Generally, they require mostly an inert atmosphere as well as harsh reaction conditions. These facts constitute challenges to the development of mild reaction conditions in the reduction of nitrilated compounds. In the light of
Graphical Abstract
Figure 1: Synthesis of mono- or dialkylated acetonitriles.
Figure 2: Cyanation through 5-chloromethyl-3-(p-substituted-phenyl)-1,2,4-oxadiazole.
Figure 3: Expanded HSQC spectrum of 4a and 3a.
Figure 4: X-ray ORTEP plots of 3a and 4e.
Scheme 1: Plausible mechanism for the formation of 3.
Scheme 2: Plausible mechanism for the formation of 4 via decyanation of 3.
One hundred years of benzotropone chemistry
- Arif Dastan,
- Haydar Kilic and
- Nurullah Saracoglu
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
Graphical Abstract
Scheme 1: Tropone (1), tropolone (2) and their resonance structures.
Figure 1: Natural products containing a tropone nucleus.
Figure 2: Possible isomers 11–13 of benzotropone.
Scheme 2: Synthesis of benzotropones 11 and 12.
Scheme 3: Oxidation products of benzotropylium fluoroborate (16).
Scheme 4: Oxidation of 7-bromo-5H-benzo[7]annulene (22).
Scheme 5: Synthesis of 4,5-benzotropone (11) using o-phthalaldehyde (27).
Scheme 6: Synthesis of 4,5-benzotropone (11) starting from oxobenzonorbornadiene 31.
Scheme 7: Acid-catalyzed cleavage of oxo-bridge of 34.
Scheme 8: Synthesis of 4,5-benzotropone (11) from o-xylylene dibromide (38).
Scheme 9: Synthesis of 4,5-benzotropone (11) via the carbene adduct 41.
Scheme 10: Heck coupling strategy for the synthesis of 11.
Scheme 11: Synthesis of benzofulvalenes via carbonyl group of 4,5-benzotropone (11).
Figure 3: Some cycloheptatrienylium cations.
Scheme 12: Synthesis of condensation product 63 and its subsequent oxidative cyclization products.
Figure 4: A novel series of benzo[7]annulenes prepared from 4,5-benzotropone (11).
Scheme 13: Preparation of substituted benzo[7]annulene 72 using the Mukaiyama-Michael reaction.
Figure 5: Possible benzo[7]annulenylidenes 73–75.
Scheme 14: Thermal and photochemical decomposition of 7-diazo-7H-benzo[7]annulene (76) and the trapping of int...
Scheme 15: Synthesis of benzoheptafulvalene 86.
Scheme 16: Synthesis of 7-(diphenylmethylene)-7H-benzo[7]annulene (89).
Scheme 17: Reaction of 4,5-benzotropone (11) with dimethyl diazomethane.
Scheme 18: Synthesis of dihydrobenzomethoxyazocine 103.
Scheme 19: Synthesis and reducibility of benzo-homo-2-methoxyazocines.
Scheme 20: Synthesis of 4,5-benzohomotropones 104 and 115 from 4,5-benzotropones 11 and 113.
Scheme 21: A catalytic deuterogenation of 4,5-benzotropone (11) and synthesis of 5-monosubstituted benzo[7]ann...
Scheme 22: Synthesis of methyl benzo[7]annulenes 131 and 132.
Scheme 23: Ambident reactivity of halobenzo[7]annulenylium cations 133a/b.
Scheme 24: Preparation of benzo[7]annulenylidene–iron complexes 147.
Scheme 25: Synthesis of 1-ethynylbenzotropone (150) and the etheric compound 152 from 4,5-benzotropone (11) wi...
Scheme 26: Thermal decomposition of 4,5-benzotropone (11).
Scheme 27: Reaction of 4,5-benzotropone (11) with 1,2-ethanediol and 1,2-ethanedithiol.
Scheme 28: Conversions of 1-benzosuberone (162) to 2,3-benzotropone (12).
Scheme 29: Synthesis strategies for 2,3-bezotropone (12) using 1-benzosuberones.
Scheme 30: Oxidation-based synthesis of 2,3-benzotropone (12) via 1-benzosuberone (162).
Scheme 31: Synthesis of 2,3-benzotropone (12) from α-tetralone (171) via ring-expansion.
Scheme 32: Preparation of 2,3-benzotropone (12) by using of benzotropolone 174.
Figure 6: Benzoheptafulvenes as condensation products of 2,3-benzotropone (12).
Scheme 33: Conversion of 2,3-benzotropone (12) to tosylhydrazone salt 182 and gem-dichloride 187.
Figure 7: Benzohomoazocines 191–193 and benzoazocines 194–197.
Scheme 34: From 2,3-benzotropone (12) to carbonium ions 198–201.
Scheme 35: Cycloaddition reactions of 2,3-benzotropone (12).
Scheme 36: Reaction of 2,3-benzotropone (12) with various reagents and compounds.
Figure 8: 3,4-Benzotropone (13) and its resonance structure.
Scheme 37: Synthesis of 6,7-benzobicyclo[3.2.0]hepta-3,6-dien-2-one (230).
Figure 9: Photolysis and thermolysis products of 230.
Figure 10: Benzotropolones and their tautomeric structures.
Scheme 38: Synthesis strategies of 4,5-benzotropolone (238).
Scheme 39: Synthesis protocol for 2-hydroxy-4,5-benzotropone (238) using oxazole-benzo[7]annulene 247.
Figure 11: Some quinoxaline and pyrazine derivatives 254–256 prepared from 4,5-benzotropolone (238).
Scheme 40: Nitration product of 4,5-benzotropolone (238) and its isomerization to 1-nitro-naphthoic acid (259)....
Scheme 41: Synthesis protocol for 6-hydroxy-2,3-benzotropone (239) from benzosuberone (162).
Scheme 42: Various reactions via 6-hydroxy-2,3-benzotropone (239).
Scheme 43: Photoreaction of 6-hydroxy-2,3-benzotropone (239).
Scheme 44: Synthesis of 7-hydroxy-2,3-benzotropone (241) from benzosuberone (162).
Scheme 45: Synthesis strategy for 7-hydroxy-2,3-benzotropone (241) from ketone 276.
Scheme 46: Synthesis of 7-hydroxy-2,3-benzotropone (241) from β-naphthoquinone (280).
Scheme 47: Synthesis of 7-hydroxy-2,3-benzotropone (241) from bicyclic endoperoxide 213.
Scheme 48: Synthesis of 7-hydroxy-2,3-benzotropone (241) by ring-closing metathesis.
Figure 12: Various monosubstitution products 289–291 of 7-hydroxy-2,3-benzotropone (241).
Scheme 49: Reaction of 7-hydroxy-2,3-benzotropone (241) with various reagents.
Scheme 50: Synthesis of 4-hydroxy-2,3-benzotropones 174 and 304 from diketones 300/301.
Scheme 51: Catalytic hydrogenation of diketones 300 and 174.
Scheme 52: Synthesis of halo-benzotropones from alkoxy-naphthalenes 306, 307 and 310.
Figure 13: Unexpected byproducts 313–315 during synthesis of chlorobenzotropone 309.
Figure 14: Some halobenzotropones and their cycloadducts.
Scheme 53: Multisep synthesis of 2-chlorobenzotropone 309.
Scheme 54: A multistep synthesis of 2-bromo-benzotropone 26.
Scheme 55: A multistep synthesis of bromo-2,3-benzotropones 311 and 316.
Scheme 56: Oxidation reactions of 8-bromo-5H-benzo[7]annulene (329) with some oxidants.
Scheme 57: Synthesis of 2-bromo-4,5-benzotropone (26).
Scheme 58: Synthesis of 6-chloro-2,3-benzotropone (335) using LiCl and proposed intermediate 336.
Scheme 59: Reaction of 7-bromo-2,3-benzotropone (316) with methylamine.
Scheme 60: Reactions of bromo-2,3-benzotropones 26 and 311 with dimethylamine.
Scheme 61: Reactions of bromobenzotropones 311 and 26 with NaOMe.
Scheme 62: Reactions of bromobenzotropones 26 and 312 with t-BuOK in the presence of DPIBF.
Scheme 63: Cobalt-catalyzed reductive cross-couplings of 7-bromo-2,3-benzotropone (316) with cyclic α-bromo en...
Figure 15: Cycloadduct 357 and its di-π-methane rearrangement product 358.
Scheme 64: Catalytic hydrogenation of 2-chloro-4,5-benzotropone (311).
Scheme 65: Synthesis of dibromo-benzotropones from benzotropones.
Scheme 66: Bromination/dehydrobromination of benzosuberone (162).
Scheme 67: Some transformations of isomeric dibromo-benzotropones 261A/B.
Scheme 68: Transformations of benzotropolone 239B to halobenzotropolones 369–371.
Figure 16: Bromobenzotropolones 372–376 and 290 prepared via bromination/dehydrobromination strategy.
Scheme 69: Synthesis of some halobenzotropolones 289, 377 and 378.
Figure 17: Bromo-chloro-derivatives 379–381 prepared via chlorination.
Scheme 70: Synthesis of 7-iodo-3,4-benzotropolone (382).
Scheme 71: Hydrogenation of bromobenzotropolones 369 and 370.
Scheme 72: Debromination reactions of mono- and dibromides 290 and 375.
Figure 18: Nitratation and oxidation products of some halobenzotropolenes.
Scheme 73: Azo-coupling reactions of some halobenzotropolones 294, 375 and 378.
Figure 19: Four possible isomers of dibenzotropones 396–399.
Figure 20: Resonance structures of tribenzotropone (400).
Scheme 74: Two synthetic pathways for tribenzotropone (400).
Scheme 75: Synthesis of tribenzotropone (400) from dibenzotropone 399.
Scheme 76: Synthesis of tribenzotropone (400) from 9,10-phenanthraquinone (406).
Scheme 77: Synthesis of tribenzotropone (400) from trifluoromethyl-substituted arene 411.
Figure 21: Dibenzosuberone (414).
Figure 22: Reduction products 415 and 416 of tribenzotropone (400).
Figure 23: Structures of tribenzotropone dimethyl ketal 417 and 4-phenylfluorenone (412) and proposed intermed...
Figure 24: Structures of benzylidene- and methylene-9H-tribenzo[a,c,e][7]annulenes 419 and 420 and chiral phos...
Figure 25: Structures of tetracyclic alcohol 422, p-quinone methide 423 and cation 424.
Figure 26: Structures of host molecules 425–427.
Scheme 78: Synthesis of non-helical overcrowded derivatives syn/anti-431.
Figure 27: Hexabenzooctalene 432.
Figure 28: Structures of possible eight isomers 433–440 of naphthotropone.
Scheme 79: Synthesis of naphthotropone 437 starting from 1-phenylcycloheptene (441).
Scheme 80: Synthesis of 10-hydroxy-11H-cyclohepta[a]naphthalen-11-one (448) from diester 445.
Scheme 81: Synthesis of naphthotropone 433.
Scheme 82: Synthesis of naphthotropones 433 and 434 via cycloaddition reaction.
Scheme 83: Synthesis of naphthotropone 434 starting from 452.
Figure 29: Structures of tricarbonyl(tropone)irons 458, and possible cycloadducts 459.
Scheme 84: Synthesis of naphthotropone 436.
Scheme 85: Synthesis of precursor 465 for naphthotropone 435.
Scheme 86: Generation of naphthotropone 435 from 465.
Figure 30: Structures of tropylium cations 469 and 470.
Figure 31: Structures of tropylium ions 471+.BF4−, 472+.BF4−, and 473+.BF4−.
Scheme 87: Synthesis of tropylium ions 471+.BF4− and 479+.ClO4−.
Scheme 88: Synthesis of 1- and 2-methylanthracene (481 and 482) via carbene–carbene rearrangement.
Figure 32: Trapping products 488–490.
Scheme 89: Generation and chemistry of a naphthoannelated cycloheptatrienylidene-cycloheptatetraene intermedia...
Scheme 90: Proposed intermediates and reaction pathways for adduct 498.
Scheme 91: Exited-state intramolecular proton transfer of 505.
Figure 33: Benzoditropones 506 and 507.
Scheme 92: Synthesis of benzoditropone 506e.
Scheme 93: Synthetic approaches for dibenzotropone 507 via tropone (1).
Scheme 94: Formation mechanisms of benzoditropone 507 and 516 via 515.
Scheme 95: Synthesis of benzoditropones 525 and 526 from pyromellitic dianhydride (527).
Figure 34: Possible three benzocyclobutatropones 534–536.
Scheme 96: Synthesis of benzocyclobutatropones 534 and 539.
Scheme 97: Synthesis attempts for benzocyclobutatropone 545.
Scheme 98: Generation and trapping of symmetric benzocyclobutatropone 536.
Scheme 99: Synthesis of chloro-benzocyclobutatropone 552 and proposed mechanism of fluorenone derivatives.
Scheme 100: Synthesis of tropolone analogue 559.
Scheme 101: Synthesis of tropolones 561 and 562.
Figure 35: o/p-Tropoquinone rings (563 and 564) and benzotropoquinones (565–567).
Scheme 102: Synthesis of benzotropoquinone 566.
Scheme 103: Synthesis of benzotropoquinone 567 via a Diels–Alder reaction.
Figure 36: Products 575–577 through 1,2,3-benzotropoquinone hydrate 569.
Scheme 104: Structures 578–582 prepared from tropoquinone 567.
Figure 37: Two possible structures 583 and 584 for dibenzotropoquinone, and precursor compound 585 for 583.
Scheme 105: Synthesis of saddle-shaped ketone 592 using dibenzotropoquinone 584.
Phosphorus pentasulfide mediated conversion of organic thiocyanates to thiols
- Chandra Kant Maurya,
- Avik Mazumder and
- Pradeep Kumar Gupta
Beilstein J. Org. Chem. 2017, 13, 1184–1188, doi:10.3762/bjoc.13.117
- systems and by the breakdown of sulfur-containing amino acids and lignin [4][5][6][7]. In laboratory, thiols can be synthesized from alcohols [8][9], alkyl halides [10], alkenes [11] and through reductive cleavage of organic thiocyanates (or simply thiocyanates hereafter) by means of alkali metals–ammonia
Graphical Abstract
Scheme 1: Conversion of organic thiocyanates to thiols.
Scheme 2: Hypothetical mechanism for conversion of thiocyanates to thiols mediated by phosphorus pentasulfide....
Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications
- Stephen Hill and
- M. Carmen Galan
Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67
- the CD by the Fe3+ ion. The selectivity towards Fe3+ was demonstrated against a panel of other transition and alkali metals and a detection limit for Fe3+ of 1.8 nM was established. The glucose-derived blue-emissive CD could be readily internalised into T24 cells, without significant cell death, and
Graphical Abstract
Scheme 1: Microwave-driven reaction of glucose in the presence of PEG-200 to afford blue-emissive CDs.
Scheme 2: Two-step synthesis of TTDDA-coated CDs generated from acid-refluxed glucose.
Scheme 3: Glucose-derived CDs using KH2PO4 as a dehydrating agent to both form and tune CD’s properties.
Scheme 4: Ultrasonic-mediated synthesis of glucose-derived CDs in the presence of ammonia.
Scheme 5: Tryptophan-derived CDs used for the sensing of peroxynitrite in serum-fortified cell media.
Scheme 6: Glucose-derived CDs conjugated with methotrexate for the treatment of H157 lung cancer cells.
Scheme 7: Boron-doped blue-emissive CDs used for sensing of Fe3+ ion in solution.
Scheme 8: N/S-doped CDs with aggregation-induced fluorescence turn-off to temperature and pH stimuli.
Scheme 9: N/P-doped hollow CDs for efficient drug delivery of doxorubicin.
Scheme 10: N/P-doped CDs applied to the sensing of Fe3+ ions in mammalian T24 cells.
Scheme 11: Comparative study of CDs formed from glucose and N-doped with TTDDA and dopamine.
Scheme 12: Formation of blue-emissive CDs from the microwave irradiation of glycerol, TTDDA and phosphate.
Scheme 13: Xylitol-derived N-doped CDs with excellent photostability demonstrating the importance of Cl incorp...
Scheme 14: Base-mediated synthesis of CDs with nanocrystalline cores, from fructose and maltose, without forci...
Scheme 15: N/P-doped green-emissive CDs working in tandem with hyaluronic acid-coated AuNPs to monitor hyaluro...
Scheme 16: Three-minute microwave synthesis of Cl/N-doped CDs from glucosamine hydrochloride and TTDDA to affo...
Scheme 17: Mechanism for the formation of N/Cl-doped CDs via key aldehyde and iminium intermediates, monitored...
Scheme 18: Phosphoric acid-mediated synthesis of orange-red emissive CDs from sucrose.
Scheme 19: Proposed HMF dimer, and its formation mechanism, that upon aggregations bestows orange-red emissive...
Scheme 20: Different polysaccharide-derived CDs in the presence of PEG-200 and how the starting material compo...
Scheme 21: Tetracycline release profiles for differentially-decorated CDs.
Scheme 22: Hyaluronic acid (HA) and glycine-derived CDs, suspected to be decorated in unreacted HA, allowing r...
Scheme 23: Cyclodextrin-derived CDs used for detection of Ag+ ions in solution, based on the formal reduction ...
Scheme 24: Cyclodextrin and OEI-derived CDs, coated with hyaluronic acid and DOX, to produce an effective lung...
Scheme 25: Cellulose and urea-derived N-doped CDs with green-emissive fluorescence.
The reductive decyanation reaction: an overview and recent developments
- Jean-Marc R. Mattalia
Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30
- -BuOH could act as a proton donor and so prevent the olefin isomerization. Alkali metals can also be used in suspension. As mentioned above, highly dispersed potassium over neutral alumina (K/Al2O3) in hexane is able to effect the reductive cleavage of alkylnitriles [18][34]. Zárraga et al. described an
- radical recombination with the nickel species produce 66. Finally, an elimination of Ar-H closes the catalytic cycle. A similar mechanism was proposed with method B. Radical reactions This part is related to radical reactions not involving alkali metals and focuses on the reduction of malononitriles and
Graphical Abstract
Scheme 1: Mechanism for the reduction under metal dissolving conditions.
Scheme 2: Example of decyanation in metal dissolving conditions coupled with deprotection [30]. TBDMS = tert-buty...
Scheme 3: Preparation of α,ω-dienes [18,33].
Scheme 4: Cyclization reaction using a radical probe [18].
Scheme 5: Synthesis of (±)-xanthorrhizol (8) [39].
Scheme 6: Mechanism for the reduction of α-aminonitriles by hydride donors.
Scheme 7: Synthesis of phenanthroindolizidines and phenanthroquinolizidines [71].
Scheme 8: Two-step synthesis of 5-unsubstituted pyrrolidines (25 examples and 1 synthetic application, see be...
Scheme 9: Synthesis of (±)-isoretronecanol 19. DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene [74].
Scheme 10: Proposed mechanism with 14a for the NaBH4 induced decyanation reaction (“BH3” = BH3·THF) [74].
Scheme 11: Reductive decyanation by a sodium hydride–iodide composite (26 examples) [81].
Scheme 12: Proposed mechanism for the reduction by NaH [81].
Scheme 13: Reductive decyanation catalyzed by nickel nanoparticles. Yields are given in weight % from GC–MS da...
Scheme 14: Decyanation of 2-cyanobenzo[b]thiophene [87].
Scheme 15: Simplified pathways involved in transition-metal-promoted reductive decyanations [93,95].
Scheme 16: Fe-catalyzed reductive decyanation. Numbers in square brackets represent turnover numbers. The TONs...
Scheme 17: Rh-catalyzed reductive decyanation of aryl nitriles (18 examples, 2 synthetic applications) [103].
Scheme 18: Rh-catalyzed reductive decyanation of aliphatic nitriles (15 examples, one synthetic application) [103].
Scheme 19: Ni-catalyzed reductive decyanation (method A: 28 examples and 2 synthetic applications; method B: 3...
Scheme 20: Reductive decyanation catalyzed by the nickel complex 58 (method A, 14 examples, yield ≥ 20% and 1 ...
Scheme 21: Proposed catalytic cycle for the nickel complex 58 catalyzed decyanation (method A). Only the cycle...
Scheme 22: Synthesis of bicyclic lactones [119,120].
Scheme 23: Reductive decyanation of malononitriles and cyanoacetates using NHC-boryl radicals (9 examples). Fo...
Scheme 24: Proposed mechanism for the reduction by NHC-boryl radicals. The other possible pathway (addition of ...
Scheme 25: Structures of organic electron-donors. Only the major Z isomer of 80 is shown [125,127].
Scheme 26: Reductive decyanation of malononitriles and cyanoacetates using organic electron-donors (method A, ...
Scheme 27: Photoreaction of dibenzylmalononitrile with 81 [128].
Scheme 28: Examples of decyanation promoted in acid or basic media [129,131,134,135].
Scheme 29: Mechanism proposed for the base-induced reductive decyanation of diphenylacetonitriles [136].
Scheme 30: Reductive decyanation of triarylacetonitriles [140].
Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study
- Nikolay O. Chalkov,
- Vladimir K. Cherkasov,
- Gleb A. Abakumov,
- Andrey G. Starikov and
- Viacheslav A. Kuropatov
Beilstein J. Org. Chem. 2016, 12, 2450–2456, doi:10.3762/bjoc.12.238
- proceeding at the coordination sites. Previously we reported paramagnetic derivatives of di-o-quinone (1, Figure 1) with alkali metals [3]. Using the protonated paramagnetic derivatives of the quinone-exTTF-quinone system we succeeded in organization of a symmetric surrounding for both coordination sites of
Graphical Abstract
Figure 1: The structural formula of acceptor–donor–acceptor triad 1.
Figure 2: The EPR spectrum of (1·)H in CHCl3, 293 K: a) experimental and b) experimental + D2O.
Scheme 1: Disproportionation of the protonated semiquinones in solution.
Scheme 2: Paramagnetic reduced protonated derivatives of the quinone 2.
Figure 3: The EPR spectrum of (1·)H3 in CHCl3, 293 K: a) experimental, b) simulated, c) experimental + D2O an...
Figure 4: The EPR spectrum of (1·−)H2 THF, 293 K: a) experimental and b) experimental + D2O). Magnified side ...
Figure 5: The well-resolved EPR spectrum of (1·−)H2 in dimethoxyethane (diluted solution), 273 K: a) experime...
Donor–acceptor type co-crystals of arylthio-substituted tetrathiafulvalenes and fullerenes
- Xiaofeng Lu,
- Jibin Sun,
- Shangxi Zhang,
- Longfei Ma,
- Lei Liu,
- Hui Qi,
- Yongliang Shao and
- Xiangfeng Shao
Beilstein J. Org. Chem. 2015, 11, 1043–1051, doi:10.3762/bjoc.11.117
- and the fullerene molecule is the guest. The fullerene molecules form the 1D columnar stacks with a center-to-center distance of around 10.3 Å, which is comparable with that of superconducting C60 complexes with alkali metals (e.g.,10.29 Å in RbCs2C60) [67]. When the ratio of fullerene molecules
Graphical Abstract
Scheme 1: Chemical structures of Ar-S-TTFs 1–8.
Figure 1: Crystal structure of 5·C70. a) Unit cell contents viewed along the short axis of 5; b) Interactions...
Figure 2: Crystal structure of 1·(C60)2·(CS2)2. a) Interactions of C60 molecule A with 1, where the blue and ...
Figure 3: Packing motifs of C60 molecules A (a) and B (b) of 1·(C60)2·(CS2)2 in the crystallographic ab-plane...
Figure 4: Crystal structure of 2·(C70)4·(PhCl)2. a) Interactions between C70 molecule A and 2; b) Interaction...
Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products
- Mikko Passiniemi and
- Ari M.P. Koskinen
Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300
- in low yield (27%) [102]. With a different unstabilized ylide 65, the enantiopurity of the Wittig product increased to >95% ee. The erosion of enantiopurity was attributed to the ylide (Ph3P=CH2) being too basic. It is well known that phosphonium ylides form stable complexes with alkali metals during
Graphical Abstract
Figure 1: Structures of limonene, carvone and thalidomide.
Figure 2: Structure of Garner’s aldehyde.
Scheme 1: (a) i) Boc2O, 1.0 N NaOH (pH >10), dioxane, +5 °C → rt; ii) MeI, K2CO3, DMF, 0 °C → rt (86% over tw...
Scheme 2: (a) AcCl, MeOH, 0 °C → reflux (99%); (b) i) (Boc)2O, Et3N, THF, 0 °C → rt → 50 °C (89%); ii) Me2C(O...
Scheme 3: (a) LiAlH4, THF, rt (93–96%); (b) (COCl)2, DMSO, iPr2NEt, CH2Cl2, −78 °C → −55 °C (99%).
Scheme 4: The Koskinen procedure for the preparation of Garner’s aldehyde. (a) i) AcCl, MeOH, 0 °C → 50 °C (9...
Scheme 5: Burke’s synthesis of Garner’s aldehyde. BDP - bis(diazaphospholane).
Figure 3: Structures of some iminosugars (7, 9), peptide antibiotics (8) and sphingosine (10) and pachastriss...
Scheme 6: Use of Garner’s aldehyde 1 in multistep synthesis.
Scheme 7: Explanation of the anti- and syn-selectivity in the nucleophilic addition reaction.
Scheme 8: Herold’s method: (a) Lithium 1-pentadecyne, HMPT, THF, −78 °C (71%); (b) Lithium 1-pentadecyne, ZnBr...
Scheme 9: (a) Ethyl lithiumpropiolate, HMPT, THF, −78 °C; (b) (S)- or (R)-MTPA, DCC, DMAP, THF, rt (18, 81%) ...
Scheme 10: Coleman’s selectivity studies and their transition state model for the co-ordinated delivery of the...
Scheme 11: (a) PhMgBr, THF, −78 °C → 0 °C [62] or (a) PhMgBr, Et2O, 0 °C [63].
Scheme 12: (a) cat. RhCl3·3H2O, cat. 26, NaOMe, Ph-B(OH)2, aq DME, 80 °C (24, 71%); (b) cat. RhCl3·3H2O, cat. ...
Scheme 13: Lithiated dithiane (3 equiv), CuI (0.3 equiv), BF3·Et2O (6 equiv), THF, −50 °C, 12 h (70%).
Scheme 14: Addition reaction reported by Lam et al. (a) 1-Hexyne, n-BuLi, THF, −15 °C or −40 °C.
Scheme 15: (a) n-BuLi, HMPT, toluene, −78 °C → rt (85%); (b) n-BuLi, ZnCl2, toluene/Et2O, −78 °C → rt (65%).
Scheme 16: (a) n-BuLi, 34, THF, −40 °C [69]; (b) n-BuLi, 35, THF, −78 °C → rt (80%) [70]; (c) n-BuLi, 35, HMPT, THF, −...
Scheme 17: (a) cat. Rh(acac)(CO)2, 42, THF, 40 °C (74%).
Scheme 18: (a) 1-PropynylMgBr, CuI, THF, Me2S, −78 °C (95%); (b) Ethynyltrimethylsilane, EtMgBr, CuI, THF, Me2...
Scheme 19: (a) cat. 50, toluene, 0 °C (52%); (b) cat. 51, toluene, 0 °C (51%); (c) cat. 52, toluene, 0 °C (50%...
Scheme 20: (a) (iPr)3SiH, cat. Ni(COD)2, dimesityleneimidazolium·HCl, t-BuOK, THF, rt.
Scheme 21: (a) Cp2Zr(H)Cl, cat. AgAsF6, CH2Cl2, rt; (b) Cp2Zr(H)Cl, 1-pentadecyne, cat. ZnBr2 in THF for anti-...
Scheme 22: (a) i) 31, n-BuLi, THF, −78 °C; ii) (S)-1, THF, −78 °C; (b) Red-Al, THF, 0 °C.
Scheme 23: (a) 61, n-BuLi, DMPU, toluene, −78 °C, then (S)-1, toluene, −95 °C (57%); (b) 61, n-BuLi, ZnCl2, to...
Scheme 24: Olefin A as an intermediate in natural product synthesis.
Scheme 25: (a) Ph3(Me)PBr, KH, benzene (66%, rac-64) or (b) AlMe3, Zn, CH2I2, THF (76%) [101]; (c) Ph3(Me)PBr, n-Bu...
Scheme 26: (a) Benzene, rt (82%) [108]; (b) K2CO3, MeOH (85%) [89]; (c) iPrOH, [Ir(COD)Cl]2, PPh3, THF, rt (81%) [114].
Scheme 27: Mechanism of the Still–Gennari modification of the HWE reaction leading to both olefin isomers.
1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions
- Astrid Hoppe,
- Faten Sadaka,
- Claire-Hélène Brachais,
- Gilles Boni,
- Jean-Pierre Couvercelle and
- Laurent Plasseraud
Beilstein J. Org. Chem. 2013, 9, 647–654, doi:10.3762/bjoc.9.73
- a carrier of stem cells [9], PLA as an implant material for stents and screws [10]. A general synthetic route for polyesters with controlled molecular weight and distribution requires the use of metal alkoxides and catalysts of transition, rare-earth and alkali metals, as initiators for the ring
Graphical Abstract
Figure 1: Molecular representations of N-heterocyclic carbenes and BMIM-2-CO2.
Scheme 1: Ring-opening polymerization of ε-caprolactone and rac-lactide by using BMIM-2-CO2 as precatalyst (1...
Scheme 2: Possible mechanism for the synthesis of PCL and PLA by ROP using BMIM-2-CO2 as precatalyst.
Scheme 3: In situ formation of monobenzylcarbonate and deactivation of N-heterocyclic carbene.
Metal-mediated aminocatalysis provides mild conditions: Enantioselective Michael addition mediated by primary amino catalysts and alkali-metal ions
- Matthias Leven,
- Jörg M. Neudörfl and
- Bernd Goldfuss
Beilstein J. Org. Chem. 2013, 9, 155–165, doi:10.3762/bjoc.9.18
- catalysis provides an effective alternative to conventional primary amino catalysis were strong acid additives are essential components. Keywords: alkali metals; aminocatalysis; DFT-calculations; Lewis acids; Michael addition; Introduction Organocatalysis based on primary or secondary amines enables a
- that very mild conditions prevail under catalytic conditions if alkali metals are used as Lewis acids, since the pH value of the dissolved catalyst is in the range of 9 (see Experimental section for details). The application of catalysts 5 and 7 (Table 1) indicates that lithium cations are the most
Graphical Abstract
Scheme 1: Activation of amine-bonded Michael acceptors by protonation versus Lewis acid interaction.
Scheme 2: Synthesis of 4-hydroxycoumarin derivatives by Michael addition [19-27].
Scheme 3: Precatalysts 5–8 and synthesis from chiral 1,2-diamines and 2-sulfobenzoic anhydrides.
Figure 1: X-ray crystallographic structure of 5. The conformation of the 2-sulfobenzoic moiety is fixed by hy...
Figure 2: Michael acceptors employed as substrates in the nucleophilic addition of 4-hydroxycoumarin (1).
Scheme 4: Computationally analyzed pathways A (C-protonation), and B (N-protonation), arising from the additi...
Scheme 5: Computed energy profile for reaction path A (C-protonation) and B (N-protonation) corresponding to ...
Figure 3: Enantio-determining transition states arising from the addition of 4-hydroxycoumarin to cyclohexeno...
Figure 4: The competing enantio-determining transition structures TS-14a and TS-14g. The reason for the desta...
Fifty years of oxacalix[3]arenes: A review
- Kevin Cottet,
- Paula M. Marcos and
- Peter J. Cragg
Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22
- found to be necessary to remove the ethanol stabilizer and to aid deprotection. Yields were up to 50%, and, interestingly, there was no template effect from any alkali metals. An analogous strategy was developed by Georghiou in 2001 to prepare asymmetric oxacalix[3]naphthalene derivatives [20], and this
- -metal complexes: The parent oxacalix[3]arenes (calixarenes with free OH groups) show little ability to bind alkali metals, and extraction studies from water to CH2Cl2 showed that this ability was enhanced only in the presence of strong bases [15]. Hampton’s purification of 3a involved the formation and
- precipitation of the Na+ salt, which would seem to indicate a significant affinity for metal cations. Surprisingly, only para-chlorooxacalix[3]arene, 3e, was found to bind alkali metals and then only when triethylamine was used to promote salt formation. The binding constants were determined by 1H NMR as 0.39 M
Graphical Abstract
Figure 1: Calixarenes and expanded calixarenes: p-tert-Butylcalix[4]arene (1), p-tert-butyldihomooxacalix[4]a...
Figure 2: Conventional nomenclature for oxacalix[n]arenes.
Scheme 1: Synthesis of oxacalix[3]arenes: (i) Formaldehyde (37% aq), NaOH (aq), 1,4-dioxane; glacial acetic a...
Figure 3: p-tert-Butyloctahomotetraoxacalix[4]arene (4a) [16].
Figure 4: X-ray crystal structure of 3a showing phenolic hydrogen bonding (IUCr ID AS0508) [17].
Scheme 2: Stepwise synthesis of asymmetric oxacalix[3]arenes: (i) MOMCl, Adogen®464; (ii) 2,2-dimethoxypropan...
Figure 5: X-ray crystal structure of heptahomotetraoxacalix[3]arene 5 (CCDC ID 166088) [21].
Scheme 3: Oxacalix[3]arene synthesis by reductive coupling: (i) Me3SiOTf, Et3SiH, CH2Cl2; R1, R2 = I, Br, ben...
Scheme 4: Oxacalix[3]naphthalene: (i) HClO4 (aq), wet CHCl3 (R = tert-butyl, 6a, H, 6b) [20].
Figure 6: Conformers of 3a.
Scheme 5: Origin of the 25:75 cone:partial-cone statistical distribution of O-substituted oxacalix[3]arenes (p...
Scheme 6: Synthesis of alkyl ethers 7–10: (i) Alkyl halide, NaH, DMF [24].
Scheme 7: Synthesis of a pyridyl derivative 11a: (i) Picolyl chloride hydrochloride, NaH, DMF [26,27].
Figure 7: X-ray crystal structure of partial-cone 11a (CCDC ID 150580) [26].
Scheme 8: Lower-rim ethyl ester synthesis: (i) Ethyl bromoacetate, NaH, t-BuOK or alkali metal carbonate, THF...
Scheme 9: Forming chiral receptor 13: (i) Ethyl bromoacetate, NaH, THF; (ii) NaOH, H2O/1,4-dioxane; (iii) S-P...
Figure 8: X-ray crystal structure of 16 (IUCr ID PA1110) [32].
Scheme 10: Lower rim N,N-diethylamide 17a: (i) N,N-Diethylchloroacetamide, NaH, t-BuOK or alkali metal carbona...
Scheme 11: Capping the lower rim: (i) N,N-Diethylchloroacetamide, NaH, THF; (ii) NaOH, H2O/1,4-dioxane; (iii) ...
Figure 9: X-ray crystal structure of 18 (CCDC ID 142599) [33].
Scheme 12: Extending the lower rim: (i) Glycine methyl ester, HOBt, dicyclohexycarbodiimide (DCC), CH2Cl2; (ii...
Scheme 13: Synthesis of N-hydroxypyrazinone derivative 23: (i) 1-[3-(Dimethylamino)propyl]-3-ethylcarbodiimide...
Scheme 14: Synthesis of 24: (i) 1-Adamantyl bromomethyl ketone, NaH, THF [39].
Scheme 15: Synthesis of 25 and 26: (i) (Diphenylphosphino)methyl tosylate, NaH, toluene; (ii) phenylsilane, to...
Figure 10: X-ray crystal structure of 27 in the partial-cone conformer (CCDC ID SUP 90399) [41].
Scheme 16: Synthesis of strapped oxacalix[3]arene derivatives 28 and 29: (i) N,N’-Bis(chloroacetyl)-1,2-ethyle...
Figure 11: A chiral oxacalix[3]arene [45].
Figure 12: X-ray crystal structure of asymmetric oxacalix[3]arene 30 incorporating t-Bu, iPr and Et groups (CC...
Scheme 17: Reactions of an oxacalix[3]arene incorporating an upper-rim Br atom with (i) Pd(OAc)2, PPh3, HCO2H,...
Scheme 18: Synthesis of acid 39: (i) NaOH, EtOH/H2O, HCl (aq) [47].
Figure 13: Two forms of dimeric oxacalix[3]arene 40 [47].
Scheme 19: Capping the upper rim: (i) t-BuLi, THF, −78 °C; (ii) NaBH4, THF/EtOH; (iii) 1,3,5-tris(bromomethyl)...
Figure 14: Oxacalix[3]arene capsules 46 and 47 formed through coordination chemistry [52,53].
Figure 15: X-ray crystal structure of the 3b-vanadyl complex (CCDC ID 240185) [57].
Scheme 20: Effect of Ti(IV)/SiO2 on 3a: (i) Ti(OiPr)4, toluene; (ii) triphenylsilanol, toluene; (iii) partiall...
Figure 16: X-ray crystal structures of oxacalix[3]arene complexes with rhenium: 3b∙Re(CO)3 (CCDC ID 620981, le...
Figure 17: X-ray crystal structure of the La2·3a2 complex (CSD ID TIXXUT) [60].
Figure 18: X-ray crystal structures of [3a∙UO2]− with a cavity-bound cation (CCDC ID 135575, left) and without...
Figure 19: X-ray crystal structure of a supramolecule comprising two [3g·UO2]− complexes that encapsulate a di...
Figure 20: X-ray crystal structure of oxacalix[3]arene 49 capable of chiral selectivity (CSD ID HIGMUF) [65].
Figure 21: The structure of derivative 50 incorporating a Reichardt dye [66].
Figure 22: Phosphorylated oxacalix[3]arene complexes with transition metals: (Left to right) 26∙Au, 26∙Mo(CO)3...
Figure 23: X-ray crystal structure of [17a·HgCl2]2 (CCDC ID 168653) [69].
Figure 24: X-ray crystal structures of 3f with C60 (CCDC ID 182801, left) [76] and a 1,4-bis(9-fluorenyl) C60 deri...
Figure 25: X-Ray crystal structure of 3i and 6a encapsulating C60 (CCDC ID 102473 and 166077) [23,79].
Figure 26: A C60 complexing cationic oxacalix[3]arene 51 [81].
Figure 27: An oxacalix[3]arene-C60 self-associating system 53 [87].
Scheme 21: Synthesis of fluorescent pyrene derivative 55: (i) Propargyl bromide, acetone; (ii) CuI, 1-azidomet...
Scheme 22: Synthesis of responsive rhodamine derivative 57: (i) DCC, CH2Cl2 [91].
Scheme 23: Synthesis of nitrobenzyl derivative 58: (i) 1-Bromo-4-nitrobenzyl acetate, K2CO3, refluxing acetone...
Figure 28: X-ray crystal structure of [Na2∙17a](PF6)2 (CCDC ID 116656) [97].
Meta-metallation of N,N-dimethylaniline: Contrasting direct sodium-mediated zincation with indirect sodiation-dialkylzinc co-complexation
- David R. Armstrong,
- Liam Balloch,
- Eva Hevia,
- Alan R. Kennedy,
- Robert E. Mulvey,
- Charles T. O'Hara and
- Stuart D. Robertson
Beilstein J. Org. Chem. 2011, 7, 1234–1248, doi:10.3762/bjoc.7.144
- nearly square planar sodium centre coordinated by two TMEDA molecules (near square planar alkali-metals are rare) [38], whereas the anion consists of two di-tert-butylzinc units bridged by a dimethylamino group. The unexpected manifestation of this bridging amide is almost certainly a consequence of
Graphical Abstract
Scheme 1: Proposed stepwise mechanism for the zincation of benzene.
Figure 1: Molecular structure of 2 with selective atom labelling. Hydrogen atoms and minor disorder component...
Scheme 2: Synergic metallation of N,N-dimethylaniline (A) with sodium TMP-zincate 1 to produce 2, which was s...
Figure 2: Molecular structure of 3 with selective atom labelling and thermal ellipsoids drawn at the 50% prob...
Scheme 3: Indirect zincation of N,N-dimethylaniline producing 4, 5 and 6, which was then quenched with I2 to ...
Figure 3: Molecular structure of 4 with selective atom labelling and thermal ellipsoids drawn at the 50% prob...
Figure 4: Solvent-separated ion-pair structure of 5 with selective atom labelling and thermal ellipsoids draw...
Figure 5: Molecular structure of 6 with selective atom labelling and thermal ellipsoids drawn at the 50% prob...
Figure 6: Aromatic region of 1H NMR spectra for deuterated benzene solutions of (a) the crude mixture obtaine...
Figure 7: Relative energy sequence of the four theoretical regioisomers of the experimentally observed produc...
