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Search for "thermal isomerization" in Full Text gives 30 result(s) in Beilstein Journal of Organic Chemistry.
The chemistry of bisallenes
- Henning Hopf and
- Georgios Markopoulos
Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225
- superior route to 88 consists of the thermal isomerization of hexakis(trimethylsilyl)benzene (89) [71][72]. Under flash vacuum pyrolysis conditions (400 °C, <0.01 Tor) 88 is produced from 89 as a mixture with several of its isomers (see below), but heating of the aromatic substrate at 200 °C for 10 h
- [87], go back to the 1930s (Scheme 31). Again, a thermal isomerization of a 1,5-hexadiyne derivative to a conjugated bisallene was employed, a process that will be discussed in detail in Section 1.4.1. Hexakis(tert-butylethynyl)ethane (117), when heated in alcoholic solution, isomerizes to the
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.
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
- . The isomers (trans,trans) and (cis,cis) are 28 and 2.6 kcal∙mol−1 more stable than the intermediate isomer, respectively. The large energy difference between (trans,trans) and (trans,cis) isomers indicates the ring strain that exists in the (trans,cis) isomer, and the thermal isomerization from (cis
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.
Molecular switches and cages
- Dirk Trauner
Beilstein J. Org. Chem. 2012, 8, 870–871, doi:10.3762/bjoc.8.97
- (Rück-Braun, Hoppmann). Two reviews discuss cis-azobenzenes with rapid thermal isomerization kinetics (Velasco), and highlight the azobenzene moiety as one of the smallest light-driven molecular motors conceivable (Merino). Issues of bistability are also addressed in an account on shape-persistent
Discovery of practical production processes for arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides): Beginning of a new era of “super-trifluoromethyl” arene chemistry and its industry
- Teruo Umemoto,
- Lloyd M. Garrick and
- Norimichi Saito
Beilstein J. Org. Chem. 2012, 8, 461–471, doi:10.3762/bjoc.8.53
- to be thermal isomerization of trans-2a to cis-2a with an acid catalyst, suggesting that the cis-isomer is more thermodynamically stable than the trans-isomer. With ZnF2/SbCl5 the cis-isomer was barely detected (run 11, Table 3). The ratio of trans-2a:cis-2a:PhSF5 was 385:0:100 after 10 min; 63:trace
Graphical Abstract
Scheme 1: Preparation of ArSF4Cl 2.
Scheme 2: Preparation of Ar(SF4Cl)n from Ar(SH)n (n = 2, 3).
Scheme 3: Reaction mechanism for the formation of ArSF4Cl.
Scheme 4: Reaction mechanism for the formation of trans and cis-ArSF4Cl.
Scheme 5: Preparation of ArSF5 with ZnF2.
Scheme 6: Preparation of PhSF5 with anhydrous HF.
Scheme 7: Preparation of 3a with HF–pyridine.
Scheme 8: Preparation of polyfluorinated ArSF5.
Scheme 9: Preparation of aryl bis- and tris(sulfur pentafluorides), Ar(SF5)n (n = 2,3).
An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts
- Ryuji Hayashi,
- John B. Feltenberger,
- Andrew G. Lohse,
- Mary C. Walton and
- Richard P. Hsung
Beilstein J. Org. Chem. 2011, 7, 410–420, doi:10.3762/bjoc.7.53
- thermal isomerization of exocyclic allenes to dienes via radical intermediates see [4][5][6][7][8][9][10][11][12]), whereby controlling E/Z ratios of the resulting diene remains a difficult problem. On the other hand, a stepwise isomerization of allenes via acid-, base-, or metal-mediated conditions seem
- argument could be used to rationalize the regioselective 1,3-hydrogen shift when acid was used. It is noteworthy that this charged transition state could also be adopted for the thermal isomerization. While still being a neutral transition state, the nitrogen atom could facilitate a polarized transition
Graphical Abstract
Scheme 1: 1,3-Hydrogen shifts of allenes.
Scheme 2: Synthesizing amido-dienes from allenamides.
Scheme 3: Synthesis of 1-amido-dienes from allenamides.
Figure 1: X-ray Structure of 10b.
Figure 2: Proposed mechanistic models.
Scheme 4: A favored pro-E TS.
Scheme 5: Unexpected competing 1,7-hydrogen shifts.
Scheme 6: Applications in pericyclic ring-closure.
Scheme 7: Cyclic 2-amido-diene synthesis.
