- Gold Catalysts Can Generate Nitrone Intermediates from a Nitrosoarene/Alkene Mixture, Enabling Two Distinct Catalytic Reactions: A Nitroso-Activated Cycloheptatriene/Benzylidene Rearrangement
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Gold-catalyzed reactions of cycloheptatrienes with nitrosoarenes yield nitrone derivatives efficiently. This reaction sequence enables us to develop gold-catalyzed aerobic oxidations of cycloheptatrienes to afford benzaldehyde derivatives using CuCl and nitrosoarenes as co-catalysts (10-30 mol %). Our density functional theory calculations support a novel nitroso-activated rearrangement, tropylium → benzylidene. With the same nitrosoarenes, we developed their gold-catalyzed [2 + 2 + 1]-annulations between nitrosobenzene and two enol ethers to yield 5-alkoxyisoxazolidines using 1,4-cyclohexadienes as hydrogen donors.
- Cheng, Mu-Jeng,Kardile, Rahul Dadabhau,Kuo, Tung-Chun,Liu, Rai-Shung,More, Sayaji Arjun
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supporting information
p. 5506 - 5511
(2021/07/31)
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- Unusual Alternating Crystallization-Induced Emission Enhancement Behavior in Nonconjugated ω-Phenylalkyl Tropylium Salts
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The alternating physical properties, especially melting points, of α,ω-disubstituted n-alkanes and their parent n-alkanes had been known since Baeyer's report in 1877. There is, however, no general and comprehensive explanation for such a phenomenon. Herein, we report the synthesis and examination of a series of novel ω-phenyl n-alkyl tropylium tetrafluoroborates, which also display alternation in their physicochemical characters. Despite being organic salts, the compounds with odd numbers of carbons in the alkyl bridge exist as room temperature ionic liquids. In stark contrast to this, the analogues with even numbers of carbons in the linker are crystalline solids. These solid nonconjugated molecules exhibit curious photoluminescent properties, which can be attributed to their ability to form through-space charge-transfer complexes to cause crystallization-induced emission enhancement. Most notably, the compound with the highest photoluminescent quantum yield in this series showed an unusual arrangement of carbocationic dimer in the solid state. A combination of XRD analysis and ab initio calculations revealed interesting insights into these systems.
- Bhadbhade, Mohan M.,Crocker, Reece D.,Lyons, Demelza J. M.,Mai, Binh Khanh,Nguyen, Thanh Vinh,Pace, Domenic P.,Wong, Wallace W. H.,Zhang, Bolong
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supporting information
p. 20384 - 20394
(2021/12/03)
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- Gold(I)-Catalyzed Synthesis of Indenes and Cyclopentadienes: Access to (±)-Laurokamurene B and the Skeletons of the Cycloaurenones and Dysiherbols
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The formal (3+2) cycloaddition between terminal allenes and aryl or styryl gold(I) carbenes generated by a retro-Buchner reaction of 7-substituted 1,3,5-cycloheptatrienes led to indenes and cyclopentadienes, respectively. These cycloaddition processes have been applied to the construction of the carbon skeleton of the cycloaurenones and the dysiherbols as well as to the total synthesis of (±)-laurokamurene B.
- Yin, Xiang,Mato, Mauro,Echavarren, Antonio M.
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supporting information
p. 14591 - 14595
(2017/10/18)
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- Cyclopropanation with gold(I) carbenes by retro-Buchner reaction from cycloheptatrienes
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Cationic gold(I) promotes the retro-Buchner reaction of 7-substituted 1,3,5-cycloheptatrienes, leading to gold(I) carbenes that cyclopropanate alkenes.
- Solorio-Alvarado, César R.,Wang, Yahui,Echavarren, Antonio M.
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supporting information; experimental part
p. 11952 - 11955
(2011/10/04)
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- Preparation of 7-alkylcyclohepta-1,3,5-trienes from organometallics and either tropylium tetrafluoroborate or 7-ethoxycyclohepta-1,3,5-triene
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The reaction of several organolithium compounds and the reaction of α-unsaturated organozinc and organoaluminium compounds with either the readily prepared tropylium tetrafluoroborate or with 7-ethoxycyclohepta-1,3,5-triene give the corresponding 7-alkylcyclohepta-1,3,5-trienes.On the other hand, with organomagnesium compounds, only 7-ethoxycyclohepta-1,3,5-triene gives the expected 7-alkylcyclohepta-1,3,5-trienes while the reaction of tropylium tetrafluoroborate is abnormal.
- Picotin, G.,Faye, A.,Miginiac, P.
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p. 245 - 251
(2007/10/02)
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- 7-METHYL- AND 7-PHENYLCYCLOHEPTA-1,3,5-TRIENES FROM BENZVALENE VIA 3,3a,4,5,6,6a-HEXAHYDRO-4,5,6-METHENOCYCLOPENTAPYRAZOLES AND TETRACYCLO2,4.03,5>HEPTANES
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The addition of benzvalene (1) to diazomethane, diazoethane, 2-diazopropane, phenyldiazomethane, and diphenyldiazomethane afforded the 1-pyrazolines 2a-g in good yields.By means of competition experiments, the relative reactivities of benzvalene (1) and norbornene with regard to diazomethane and 2-diazopropane have been determined.The fact that benzvalene reacts about twice as fast as norbornene with both diazoalkenes cannot be rationalized on the basis of frontier orbital energies.On direct photolysis, the pyrazolines 2a-g were converted into the tetracyclo2,4.03,5>heptanes 4a-g exclusively.These compounds gave the 1,3,5-cycloheptatrienes 5a,b,d,e,g in high yields on treatment with silver ions, thus providing better access to 7,7-dimethyl-(5d) and 7,7-diphenylcycloheptatriene (5g) than before.Surprisingly, the latter compound is in equilibrium with a substantial quantity of the norcaradiene form.The heat of reaction for the rearrangement of 4a to 5a has been determined, which allows to derive the heat of formation of tetracyclo2,4.03,5>heptane (4a).
- Christl, Manfred,Brunn, Erich,Roth, Wolfgang R.,Lennartz, Hans-Werner
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p. 2905 - 2916
(2007/10/02)
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- Synthesis and Valence Tautomerism of 4(8)-Monosubstituted Homotropilidenes
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A synthesis of 4(8)-monosubstituted homotropilidenes (bicycloocta-2,5-dienes) is described, which starts from the Diels-Alder adducts 10b - e of 7-monosubstituted cycloheptatrienes and diazomethane.The same synthetic goal is reached by starting from the Diels-Alder adduct 10a of cycloheptatriene itself and diazoethane, though with the opposite substituent position on the homotropilidene framework.Along this route, endo-8-methyl-, endo-8-isopropyl-, endo-8-phenyl- and exo-8-methylhomotropilidene have been made which display a more or less pronounced valence tautomerism.
- Maas, Gerhard,Kettenring, Juergen K.
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p. 627 - 644
(2007/10/02)
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- Reaction of benzyne with cycloheptatriene preparation and thermolysis of some benzo(C9H10) hydrocarbons
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The title reaction gave a 2+2 cycloadduct, 8,9-benzo-cis-bicyclo[5.2.0]nona-2,4,8-triene 7, together with ene product, 7-phenylcycloheptatriene. The structure of 7 was confirmed by catalytic reduction to give 8,9-benzo-cis-bicyclo[5.2.0]non-8-ene, which was also obtained in the reaction of benzyne with cycloheptene, and by reduction of the known 8,9-benzobicyclo[5.2.0]nona-1,8-diene. Other benzo(C9H10) hydrocarbons which have been synthesised are 7,8-benzobicyclo[4.2.1]nona-2,4,7-triene 5, 2,3-benzobicyclo[6.1.0]nona-2,4,6-triene 28 and 4,5-benzobicyclo[6.1.0]nona-2,4,6-triene 29. The thermolysis of 7, 28, 29 and of 3,4-benzo-exo-endo-tetracyclo[4.3.1.03,4.07,9]dec-3-en-10-one, 25, is described.
- Lombardo,Wege
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p. 3945 - 3952
(2007/10/06)
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