Antibacterial structure–activity relationship studies of several tricyclic sulfur-containing flavonoids
- Lucian G. Bahrin,
- Henning Hopf,
- Peter G. Jones,
- Laura G. Sarbu,
- Cornelia Babii,
- Alina C. Mihai,
- Marius Stefan and
- Lucian M. Birsa
Beilstein J. Org. Chem. 2016, 12, 1065–1071, doi:10.3762/bjoc.12.100
Graphical Abstract
Figure 1: The molecular structure of tricyclic flavonoid 1.
Scheme 1: Synthesis of flavanones 4a–m and tricyclic flavonoids 5a–m. Conditions: i) EtOH, reflux, 4 h; ii) H2...
Figure 2: The syn and anti-isomers of flavanones 4.
Figure 3: Molecular structures of 4d (left) and 4f (right). Ellipsoids represent 50% probability levels [24].
Figure 4: Molecular structure of 5a (left, both independent molecules) and 5b (right, one of two independent ...
[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
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...
The chemical behavior of terminally tert-butylated polyolefins
- Dagmar Klein,
- Henning Hopf,
- Peter G. Jones,
- Ina Dix and
- Ralf Hänel
Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139
Graphical Abstract
Scheme 1: The polyenes 2 stabilized by terminal tert-butyl substituents.
Scheme 2: The catalytic hydrogenation of diene 3.
Figure 1: The structure of compound 4 in the crystal. Ellipsoids correspond to 30% probability levels.
Scheme 3: The catalytic hydrogenation of triene 7.
Scheme 4: Addition of bromine to model dienes.
Scheme 5: Bromine addition to diene 3 and triene 7.
Scheme 6: Bromine addition to the higher oligoenes 19–22.
Figure 2: (a) The structure of compound 24 in the crystal. Ellipsoids correspond to 50% probability levels. (...
Figure 3: The structure of compound 25 in the crystal. This was a structure of poor quality and served only t...
Scheme 7: Epoxidation of triene 7 with MCPBA and DMDO.
Scheme 8: Epoxidation of tetraene 19 with MCPBA and DMDO.
Scheme 9: Diels–Alder addition of PTAD (36) to triene 7 and tetraene 19.
Figure 4: The structure of compound 37 in the crystal. Only one of two independent molecules is shown. Ellips...
Scheme 10: Diels-Alder addition of oligoenes 20 and 21 with PTAD (36).
Scheme 11: Addition of excess PTAD (36) to hexaene 21 and heptaene 22.
Scheme 12: TCNE addition to oligoolefins: from tetraene 19 to nonaene 42.
Figure 5: The structure of compound 43 in the crystal. Only one of two independent molecules is shown. Ellips...
Scheme 13: Photochemical experiments with tetraene 19.
Figure 6: The structure of compound 52 in the crystal. Ellipsoids correspond to 50% probability levels.
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
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...
Attempts to prepare an all-carbon indigoid system
- Şeref Yildizhan,
- Henning Hopf and
- Peter G. Jones
Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42
Graphical Abstract
Scheme 1: From indigo to heteroindigo derivatives and all-carbon-indigo.
Scheme 2: Attempts to prepare the α-methylene ketones 12 and 13.
Figure 1: a) Both independent molecules of compound 13 in the crystal; ellipsoids represent 50% probability l...
Scheme 3: Dimerization of 13 under McMurry conditions.
Figure 2: a) The molecule of compound 17 in the crystal; ellipsoids represent 50% probability levels. Only th...
Scheme 4: Dimerization of indan-1-one (18) by a stepwise approach.
Scheme 5: Methylenation of 19 and bisalkylation of the product 23 with 1,2-dibromoethane.
Figure 3: The molecule of compound 23 in the crystal. Ellipsoids represent 50% probability levels. Only the a...
Figure 4: a) The molecule of compound 24 in the crystal. Ellipsoids represent 50% probability levels. Only th...
Figure 5: One of the two independent molecules of compound 25 in the crystal. Ellipsoids represent 50% probab...
Scheme 6: Cross-conjugated hydrocarbons by Thiele condensation.
Figure 6: a) The molecule of compound 30 in the crystal. Ellipsoids represent 50% probability levels. Only th...
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
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
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
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.
A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H)-furanones
- Jubi John,
- Eliza Târcoveanu,
- Peter G. Jones and
- Henning Hopf
Beilstein J. Org. Chem. 2014, 10, 1462–1470, doi:10.3762/bjoc.10.150
Graphical Abstract
Figure 1: Bioactive molecules I [19], II [26], III & IV [21,22] with 3(2H)-furanone moiety.
Scheme 1: Pd-catalyzed synthesis of 3(2H)-furanones from activated alkenes [40].
Scheme 2: Pd-catalyzed synthesis of 3(2H)-furanone from tosylimine 1a.
Figure 2: Generalisation with aromatic and aliphatic imines (reaction conditions: 1 (1.0 equiv), 2 (1.1 equiv...
Figure 3: Thermal ellipsoid diagrams (50% probability levels) of 4-substituted-3(2H)-furanones 7 (above) and ...
Scheme 3: Mechanism of formation of the 3(2H)-furanone derivative from an imine.
Scheme 4: Pd-catalyzed synthesis of 3(2H)-furanone from diazoester 19a.
Figure 4: Generalisation with diazo esters (reaction conditions: 19 (1.0 equiv), 2 (1.1 equiv), Pd(PPh3)4 (5 ...
Scheme 5: Synthesis of aza-prostaglandin analogue.
The preparation of several 1,2,3,4,5-functionalized cyclopentane derivatives
- André S. Kelch,
- Peter G. Jones,
- Ina Dix and
- Henning Hopf
Beilstein J. Org. Chem. 2013, 9, 1705–1712, doi:10.3762/bjoc.9.195
Graphical Abstract
Scheme 1: The first members of the [n]radialene series and retrosynthesis for [5]radialene (3).
Scheme 2: Preparation of cis,cis,cis,cis-1,2,3,4,5-pentakis(hydroxymethyl)cyclopentane (16) according to Tolb...
Scheme 3: The preparation of derivatives of 16 better suited for nucleophilic substitution and elimination.
Figure 1: Structure of 19 in the crystal; ellipsoids represent 50% probability levels.
Scheme 4: Preparation of the pentaacetate 21 from 16.
Scheme 5: Preparation of the cycloheptadiene octaesters 24/25 according to Diels [11] and Le Goff [13], respectively,...
Figure 2: Structure of 24 in the crystal; ellipsoids represent 30% probability levels.
Figure 3: Structure of 26 in the crystal; ellipsoids represent 30% probability levels.
Scheme 6: Derivatives derived from the pentaester mixture 26/27.
Scheme 7: Bromination of 1,2,3,4,5-pentamethylcyclopenta-1,3-diene (8).
Figure 4: Structure of 32 in the crystal; ellipsoids represent 50% probability levels.
Polar reactions of acyclic conjugated bisallenes
- Reiner Stamm and
- Henning Hopf
Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5
Graphical Abstract
Scheme 1: The alkylated conjugated bisallenes 1– 3 as model systems for polar reactions.
Scheme 2: Alkylation and silylation of 2.
Scheme 3: Allylation of the monoanion 4.
Scheme 4: Metalation/silylation of hydrocarbon 3.
Scheme 5: Quenching of 4 with DMF and acetone.
Scheme 6: Further reactions of 2/4 with various electrophiles.
Scheme 7: Oxidation of conjugated bisallenes with different oxidizing agents according to [26].
Scheme 8: Oxidation of 2, 7 and 5 with MMPP.
Scheme 9: Oxidation of the asymmetric bisallene 3 by air.
Scheme 10: Epoxidation of the disilylbisallenes 11 and 12.
Scheme 11: The addition of HCl and HBr to the bisallenes 2 and 5.
Scheme 12: The addition of bromine to the bisallene 2.
Scheme 13: The addition of iodine to the conjugated bisallenes 61, 2 and 3.
Scheme 14: Addition of chlorosulfonyl isocyanate (CSI, 66) to allenes.
Tricyclic flavonoids with 1,3-dithiolium substructure
- Lucian G. Bahrin,
- Peter G. Jones and
- Henning Hopf
Beilstein J. Org. Chem. 2012, 8, 1999–2003, doi:10.3762/bjoc.8.226
Graphical Abstract
Figure 1: Polycyclic flavonoids.
Scheme 1: The synthesis of flavonoids 6 and 7.
Figure 2: Diastereoisomers of flavonoids 6.
Figure 3: Molecular structure of flavonoid 6a in the solid state. Ellipsoids represent 50% probability levels...
Figure 4: Molecular structure of flavonoid 6b in the solid state. Ellipsoids represent 50% probability levels...
Figure 5: Molecular structure of flavonoid 7a in the solid state. Ellipsoids represent 50% probability levels....
The chemistry of bisallenes
- Henning Hopf and
- Georgios Markopoulos
Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225
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.
Synthesis of 2,6-disubstituted tetrahydroazulene derivatives
- Zakir Hussain,
- Henning Hopf,
- Khurshid Ayub and
- S. Holger Eichhorn
Beilstein J. Org. Chem. 2012, 8, 693–698, doi:10.3762/bjoc.8.77
Graphical Abstract
Scheme 1: Preparation of carbene adducts 4 [18] and 5.
Scheme 2: Preparation of the cycloheptatrienes 7 and 8 [18,20].
Scheme 3: Preparation of derivatives 9 and 10.
Perhydroazulene-based liquid-crystalline materials with smectic phases
- Zakir Hussain,
- Henning Hopf and
- S. Holger Eichhorn
Beilstein J. Org. Chem. 2012, 8, 403–410, doi:10.3762/bjoc.8.44
Graphical Abstract
Figure 1: Overall molecular structure of the perhydroazulene core with trans-stereochemistry.
Scheme 1: Stereochemistry of carbene adducts 1a and 1b.
Scheme 2: Preparation of the tropylidenes 4a and 4b.
Scheme 3: Formation of esters 5a and 5b and the corresponding acids 6a and 6b.
Scheme 4: Preparation of 8a and 8b.
Scheme 5: Preparation of 10a and 10b.
Intraannular photoreactions in pseudo-geminally substituted [2.2]paracyclophanes
- Henning Hopf,
- Vitaly Raev and
- Peter G. Jones
Beilstein J. Org. Chem. 2011, 7, 658–667, doi:10.3762/bjoc.7.78
Graphical Abstract
Scheme 1: [2.2]Paracyclophanes as scaffolds for intraannular photodimerization reactions in solution.
Scheme 2: Stereospecific intramolecular [2+2]photoadditions using [2.2]paracyclophane spacers.
Scheme 3: Different conformations of pseudo-geminal divinyl[2.2]paracyclophane.
Scheme 4: Preparation of tetraene 11.
Scheme 5: Photolysis of tetraene 11.
Figure 1: The molecule of compound 13 in the crystal. Ellipsoids correspond to 30% probability levels.
Scheme 6: Photolysis of trans,trans-dienal 10.
Figure 2: The molecule of compound 15 in the crystal. Ellipsoids correspond to 30% probability levels.
Scheme 7: Cis–trans-isomerizations of the double bonds of the pseudo-geminal cyclophanes 11 and 19.
Scheme 8: Preparation of the vinylcyclopropanes 22–24.
Figure 3: The two independent molecules of compound Z,Z-22 in the crystal. Ellipsoids correspond to 50% proba...
Figure 4: The molecule of compound 23 in the crystal. Ellipsoids correspond to 50% probability levels.
Figure 5: The molecule of compound 24 in the crystal. Ellipsoids correspond to 30% probability levels.
Reciprocal polyhedra and the Euler relationship: cage hydrocarbons, CnHn and closo-boranes [BxHx]2−
- Michael J. McGlinchey and
- Henning Hopf
Beilstein J. Org. Chem. 2011, 7, 222–233, doi:10.3762/bjoc.7.30
Graphical Abstract
Figure 1: Molecular analogues of the Platonic solids.
Figure 2: The structure of [Mo6Cl8]4+ demonstrates the reciprocal relationship between the cube and the octah...
Figure 3: The deltahedra corresponding to the structures of the closo-boranes [BxHx]2−.
Scheme 1: The first synthesis of a tetrahedrane 19 by Maier.
Scheme 2: The conversion of Dewar benzenes to [3]-prismanes.
Scheme 3: Synthesis of [3]prismane 9 by Katz.
Scheme 4: Synthesis of cubane 10 by Eaton.
Scheme 5: Synthesis of cubane 10 by Pettit.
Scheme 6: Failed routes to [5]-prismane 11.
Scheme 7: Synthesis of [5]prismane 11 by Eaton.
Scheme 8: Retrosynthetic analysis for several approaches to dodecahedrane 16.
Scheme 9: Paquette´s synthesis of dodecahedrane 16.
Scheme 10: Prinzbach´s synthesis of dodecahedrane 16.
Figure 4: The as yet unknown polyhedranes 12–15.
Figure 5: Coupling of two Dewar benzenes.
Scheme 11: A possible route to octahedrane 12.
Scheme 12: A possible route to nonahedrane 13.
Figure 6: Capping [4]peristylane with a four-membered ring system.
Scheme 13: A possible route to decahedrane 14.
Figure 7: A possible route to undecahedrane 15 (left: side view; right: top view).
Scheme 14: Synthetic routes to trigonal prismatic hexasilanes 71a and hexagermanes 71b.
Scheme 15: Synthetic routes to octasila- and octagerma-cubanes.
Scheme 16: Synthesis of an octastannacubane and a decastannapentaprismane.
Scheme 17: Synthesis of a heterocubane.
Figure 8: D3d symmetric C8H8, a bis-truncated cubane.
Preparation and NMR spectra of four isomeric diformyl[2.2]paracyclophanes (cyclophanes 66)
- Ina Dix,
- Henning Hopf,
- Thota B. N. Satyanarayana and
- Ludger Ernst
Beilstein J. Org. Chem. 2010, 6, 932–937, doi:10.3762/bjoc.6.104
Graphical Abstract
Scheme 1: Preparation of the four [2.2]paracyclophane dialdehydes 4 by cycloaddition (ps - pseudo).
Scheme 2: Spin systems of the CH2CH2 protons in the isomeric dialdehydes 4. Protons at C-9 and C-10 in ps-gem...
Figure 1: CH2CH2 regions of the 600 MHz 1H NMR spectra of the isomeric dialdehydes 4, a: ps-gem, b: ps-meta, ...
Scheme 3: NOEs observed for ps-ortho-4 when the 5-H resonance is irradiated.
A surprising new route to 4-nitro-3-phenylisoxazole
- Henning Hopf,
- Aboul-fetouh E. Mourad and
- Peter G. Jones
Beilstein J. Org. Chem. 2010, 6, No. 68, doi:10.3762/bjoc.6.68
Graphical Abstract
Scheme 1: Preparation of 2 and 4 by treatment of cinnamyl alcohol (1).
Figure 1: The crystal structure of compound 4. Ellipsoids correspond to 50% probability levels.
Figure 2: Packing diagram of compound 4 viewed perpendicular to (101). Hydrogen bonds are indicated by thick ...
Scheme 2: Suggested mechanism for the formation of 4.
A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions
- Marc Debeaux,
- Kai Brandhorst,
- Peter G. Jones,
- Henning Hopf,
- Jörg Grunenberg,
- Wolfgang Kowalsky and
- Hans-Hermann Johannes
Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31
Graphical Abstract
Scheme 1: Behaviour of benzanthrone (1) towards phenylmagnesium chloride (a), phenyl lithium (b), and bipheny...
Figure 1: 1H NMR spectra (200 MHz) of 4 in CDCl3 solution and time dependence.
Scheme 2: Proposed mechanism for the formation of 4 and its oxidation to 7.
Scheme 3: Conversion of the enol 4 under acidic conditions and reaction products.
Scheme 4: Proposed mechanism for the formation of spiro compound 11 and bicyclo[4.3.1]decane derivative 12.
Scheme 5: Proposed mechanism for the formation of 13.
Scheme 6: Proposed mechanism for the formation of 18 as a hydride source and further conversion to 7.
Figure 2: Ellipsoid representation (50% level) of compound 7 in the crystal.
Figure 3: Packing diagram of compound 7 viewed parallel to b; hydrogen bonds C-H···O are indicated by dashed ...
Figure 4: Ellipsoid representation (50% level) of compound 11 in the crystal.
Figure 5: Packing diagram of compound 11 viewed perpendicular to the bc plane; hydrogen bonds C-H···π are ind...
Figure 6: Ellipsoid representation (50% level) of compound 13 (d6-DMSO solvate) in the crystal. Hydrogen bond...
Figure 7: Packing diagram of compound 13 viewed parallel to c; DMSO molecules (including their hydrogen bonds...
Reversible intramolecular photocycloaddition of a bis(9-anthrylbutadienyl)paracyclophane – an inverse photochromic system. (Photoactive cyclophanes 5)
- Henning Hopf,
- Christian Beck,
- Jean-Pierre Desvergne,
- Henri Bouas-Laurent,
- Peter G. Jones and
- Ludger Ernst
Beilstein J. Org. Chem. 2009, 5, No. 20, doi:10.3762/bjoc.5.20
Graphical Abstract
Figure 1: Schematic representation of a photochromic system. The reverse reaction can be a photochemical or t...
Figure 2: Photochromic reaction of pseudo-gem disubstituted tetraene [2.2]cyclophane 1 in acetonitrile, conc....
Figure 3: Molecular structure of 4,13-bis[(1E,3E)-4-(9-anthracenyl)-buta-1,3-dienyl][2.2]paracyclophane (2).
Scheme 1: Preparation of 2 (last step), using the Wittig reaction. The preparation of 3 has been described in...
Figure 4: Molecular structure of 2 in the crystal. Radii are arbitrary; only selected H atoms are shown.
Figure 5: Projection of the molecular structure of 2 exhibiting the closest internuclear distances (distances...
Figure 6: Electronic absorption spectra of 2 (conc. ca 10−4 M) in MCH (full line) and CH3CN (dotted line) at ...
Figure 7: Irradiation of 2 (2.6 × 10−5 M) in CH3CN at 400 nm at 20 °C. The spectra were recorded at various t...
Figure 8: Irradiation at 306 nm of the photoproduct 4 obtained at 400 nm in the same setup; the spectra were ...
Figure 9: Reversibility of the formation of the photoproduct 4 at 400 nm (40 min) and photodissociation of 4 ...
Figure 10: 1H NMR spectra (400 MHz, CDCl3). A: Compound 2, B: Compound 4.
Figure 11: Proposed structure of 4 (1,4 : 2′,3′-cycloadduct).
