- The Configuration and Conformation of the Tricyclo2,5>dodecan-11-ols Determined by 1H NMR Spectroscopy using the Shift Reagent Eu(fod)3
-
The isomeric tricyclo2,5>dodecan-11-ols have been synthesized from the (6+4) cycloaddition product of tropone with cyclopentadiene.The configuration and conformation of each isomer was determined from the proton shift gradients induced in the olefinic proton signals in the 1H NMR spectra of intermediate compounds by Eu(fod)3.
- Mason, Timothy J.
-
-
Read Online
- A New and Simple Synthesis of Tropones
-
3- and 4-Halogenocycloheptatrienones can be prepared from the Δ2- and Δ3-norcarenes (1), (2), and (3) by an allylic oxidation-dehydrohalogenation sequence; evidence for the intermediacy of the bicyclic enones (4)-(7) in the formation of the troponoid skeleton is presented.
- Banwell, Martin G.
-
-
Read Online
- Organocatalytic stereoselective [8+2] and [6+4] cycloadditions
-
Cycloadditions that involve more than six I € electrons are termed higher-order cycloadditions and are an excellent tool for solving complex synthetic challenges, as they provide direct access to polycyclic scaffolds that contain medium-sized rings. They have interesting synthetic potential for the discovery of new bioactive molecules and in natural product synthesis. It is peculiar that stereocontrolled [8+2] and [6+4] cycloadditions have been largely neglected for the past 50 years. Here we demonstrate a cross-dienamine activation of 2-cyclopentenone and the unprecedented endocyclic linear-dienamine activation of 2-cyclohexenones and 2-cycloheptenones. These dienamine intermediates undergo aminocatalytic stereoselective [8+2], [6+4] and formal [4+2] cycloadditions with various heptafulvenes. The periselectivities of the cycloadditions are controlled based on the ring size of the 2-cycloalkenones and the substitution patterns of the heptafulvenes. The chiral products obtained undergo various chemical and photochemical single-step transformations that give access to other classes of all-carbon polycyclic scaffolds.
- Mose, Rasmus,Preegel, Gert,Larsen, Jesper,Jakobsen, Sofie,Iversen, Eva H?gh,J?rgensen, Karl Anker
-
-
Read Online
- Synthesis, structure, and reactivity of a gold carbenoid complex that lacks heteroatom stabilization
-
Hydride abstraction from the neutral gold cycloheptatrienyl complex [(P)Au(η1-C7H7)] (P=P(tBu) 2(o-biphenyl)) with triphenylcarbenium tetrafluoroborate at -80 C led to the isolation of the cationic gold cycloheptatrienylidene complex [(P)Au(η1-C7H6)]+ BF 4- in 52 yield, which was characterized in solution and by single-crystal X-ray diffraction. This cycloheptatrienylidene complex represents the first example of a gold carbenoid complex that lacks conjugated heteroatom stabilization of the electron-deficient C1 carbon atom. The cycloheptatrienylidene ligand of this complex is reactive; it can be reduced by mild hydride donors, and converted to tropone in the presence of pyridine N-oxide. Hydride abstraction from the neutral gold cycloheptatrienyl complex 1 (P=P(tBu)2 (o-biphenyl)) with Ph3C+ BF 4- formed the cationic gold cycloheptatrienylidene complex 2, which was characterized by single-crystal X-ray diffraction. The cycloheptatrienylidene ligand of 2 is reactive; it can be reduced by mild hydride donors, and converted into tropone in the presence of pyridine N-oxide.
- Harris, Robert J.,Widenhoefer, Ross A.
-
-
Read Online
- DDQ-mediated oxidative coupling reaction of N,N-dimethyl enaminones with cycloheptatriene
-
An efficient 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)-mediated oxidative coupling reaction of N,N-dimethyl enaminones with cycloheptatriene is developed. It provides a variety of α-alkenylated 1,3-dicarbonyl compounds in moderate to good yields under mild conditions.
- Cheng, Dongping,Yu, Chenze,Pu, Yueqi,Xu, Xiaoliang
-
supporting information
(2022/01/23)
-
- Continuous Endoperoxidation of Conjugated Dienes and Subsequent Rearrangements Leading to C-H Oxidized Synthons
-
We have investigated the continuous flow photooxidation of several conjugated dienes and subsequent rearrangement using a practical and safe continuous-flow homemade engineered setup. End-to-end approaches involving endoperoxidation, Kornblum-DeLaMare rearrangement, and additional rearrangements are comprehensively detailed with optimization, scope, and scale-up to obtain useful hydroxyenones, furans, and 1,4-dicarbonyl building blocks.
- De Souza, Juliana M.,Brocksom, Timothy J.,McQuade, D.Tyler,De Oliveira, Kleber T.
-
p. 7574 - 7585
(2018/06/11)
-
- Dialkylated Dihydroazulene and Vinylheptafulvene Derivatives – Synthesis and Switching Properties
-
Functionalization of molecular photoswitches at specific positions offers a way of tuning their switching properties. The work presented here describes the development of a new protocol towards the synthesis and functionalization of the dihydroazulene/vinylheptafulvene (DHA/VHF) photo-/thermoswitch. The key step is a facile condensation reaction using a functionalized tropone derivative, and the new synthetic method was employed in the regioselective preparation of a novel dimethyl-substituted DHA photoswitch. This compound presents the first accessible derivative with alkyl groups on the seven-membered ring of the system ― at positions C5 and C7. From experimental and theoretical kinetics studies on the thermal VHF-to-DHA electrocyclic reaction, the influence of the electron-donating methyl groups was elucidated. In addition, we subjected a small selection of 4,8a-dialkylated compounds to a computational study to elucidate how steric interactions can alter the relative DHA–VHF stabilities. The synthetic methodology offers access to novel DHA scaffolds and substitution patterns, which in turn can lead to systems that can help to address broader questions concerning the potential applicability of the DHA/VHF system in the context of solar-thermal energy-storage systems or other photochromic applications.
- Lubrin, Nickie C. M.,Vlasceanu, Alexandru,Frandsen, Benjamin N.,Skov, Anders B.,Kilde, Martin Dr?hse,Mikkelsen, Kurt V.,Nielsen, Mogens Br?ndsted
-
supporting information
p. 2932 - 2939
(2017/06/06)
-
- Phenylhydroxycarbene
-
Phenylhydroxycarbene (Ph-C-OH, 1), the parent of all arylhydroxycarbenes, was generated by high-vacuum flash pyrolysis of phenylglyoxylic acid at 600 °C and spectroscopically characterized (IR, UV-vis) via immediate matrix isolation in solid Ar at 11 K. The identity of 1 was unequivocally confirmed by the precise agreement between the observed IR bands and (unscaled) anharmonic vibrational frequencies computed from a CCSD(T)/cc-pVDZ quartic force field. The UV-vis spectrum of 1 displays a broad band with maximum absorption at 500 25 nm (2.5 ± 0.1 eV) that extends to ～640 nm (1.9 eV), in full accord with combined CCSD(T)/cc-pVQZ and EOM-CCSD/cc-pVTZ computations that yield a gas-phase vertical (adiabatic) excitation energy of 2.7 (1.9) eV. Unlike singlet phenylchlorocarbene, 1 does not undergo photochemical ring expansion. Instead, 1 exhibits quantum-mechanical hydroGenetunneling to benzaldehyde underneath a formidable barrier of 28.8 kcal mol-1, even at cryogenic temperatures. The remarkable hydroGenetunneling mechanism is supported by the temperature insensitivity of the observed half-life (2.5 h) and substantiated by a comparable theoretical half-life (3.3 h) determined from high-level barrier penetration integrals computed along the intrinsic reaction path. As expected, deuteration turns off the tunneling mechanism, so d-1 is stable under otherwise identical conditions.
- Gerbig, Dennis,Reisenauer, Hans Peter,Wu, Chia-Hua,Ley, David,Allen, Wesley D.,Schreiner, Peter R.
-
supporting information; scheme or table
p. 7273 - 7275
(2010/07/14)
-
- Ring-expansion protocol: Preparation of synthetically versatile dihydrotropones
-
A ring-expansion protocol that consisted of the 1,2-addition of various enolate nucleophiles to 6-trimethylsiloxy-2- cyclohexene-1-one (1) and the NaIO4-promoted oxidative ring opening of the resulting diols 2, followed by an intramolecular Kno
- Do, Young-Sun,Sun, Ruiying,Kim, Hee Jin,Yeo, Jung Eun,Bae, Sung-Hee,Koo, Sangho
-
supporting information; experimental part
p. 917 - 920
(2009/06/20)
-
- Homocoupling of halotropones promoted by bis(1,5-cyclooctadiene) nickel in the presence of tris(1-pyrazolyl)methane: an easy route to [Bi-1,3,5- cycloheptatrien-1-yl]-7,7'-diones
-
An efficient homocoupling of 2-halotropones, to afford 2,2'-bitropones, occurs in toluene at rt in the presence of stoichiometric amounts of [Ni(cod)2] and tris(1-pyrazolyl)methane ligand, in a 1:1 molar ratio. This methodology was extended to aryl halides. Copyright Taylor & Francis Group, LLC.
- Funaioli, Tiziana,Cavazza, Marino
-
experimental part
p. 1592 - 1600
(2009/10/17)
-
- Allylic oxidation: Easy synthesis of alkenones from activated alkenes with TEMPO
-
Activated alkenes and dienes are converted into the corresponding alkenone in excellent yields (>90%). In aqueous acetonitrile, the transformations are catalyzed by 2,2,6,6-tetramethyl-1-oxopiperidinium (TEMPO+) in the presence of water and 2,6-lutidine. TEMPO+ cations were regenerated electrochemically from the radical parent (TEMPO.) at a vitreous carbon anode.
- Breton, Tony,Liaigre, Denis,Belgsir, El Mustapha
-
p. 2487 - 2490
(2007/10/03)
-
- Photooxygenation of 5- and 6-chloro-1,3-cycloheptadienes and reactions of their endoperoxides with base: Effects of the chloro substituent on the reactions
-
Photooxygenation reactions of 5- and 6-chlorocycloheptadienes 6 and 7 gave bicyclic endoperoxides 10-13. The endoperoxides 10 and 13 are major products due to the steric effects of the chloro substituent. The reactions of endoperoxide 10 with NEt3 under different conditions gave 1,4-epoxide 14, hydroxyenone 15, diketone 16, acetates 17-19 and diacetate 20. The reaction of endoperoxide 10 with pyridine and Ac2O gave diacetate 20 and dienone 21. The reaction of endoperoxide 13 with NEt3 gave tropone. The effects of the chloro substituent are discussed.
- Menzek, Abdullah,Senguel, M. Emin,Cetinkaya, Yasin,Ceylan, Selami
-
p. 209 - 214
(2007/10/03)
-
- On the non-classical course of Polonowski reactions of N-benzylmorpholine- N-oxide (NBnMO)
-
The Polonowski reaction of NBnMO (4) afforded tropone (10) and the novel isoindole 11 besides the expected products benzaldehyde and acetmorpholide, in a temperature-dependent ratio. The reaction proceeded via two primary carbenium-iminium ion intermediates, an exo-centered species 5 which underwent a benzylium-tropylium type rearrangement, and a ring-centered species 6, which reacted further to isoindole 11 by intramolecular electrophilic substitution. The experimental findings were in good agreement with DFT computational data.
- Rosenau, Thomas,Schmid, Peter,Kosma, Paul
-
p. 3483 - 3487
(2007/10/03)
-
- Trapping of a cycloheptatetraene in the reaction of atomic carbon with phenol
-
Reaction of atomic carbon with phenol generates tropone in a reaction postulated to proceed via the hydroxycycloheptatetraenes, which rearrange to tropone. When the hydroxyphenylcarbenes are generated by the C atom deoxygenation of the corresponding aldehydes, the meta and para isomers produce tropone; the ortho isomer does not.
- Sevin, Fatma,S?kmen, Ikay,Düz, Bülent,Shevlin, Philip B.
-
p. 3405 - 3407
(2007/10/03)
-
- Unambiguous detection of 2,4,6-cycloheptatrien-1-ol by NMR spectroscopy and trapping with phenyltriazolinedione
-
For the first time, the title alcohol 3 was unambiguously detected as a transient intermediate leading to ditropylether (6) in a cation-anion reaction between the tropylium ion (5) and hydroxide ion in an aqueous solution by NMR spectroscopy. It was also found that 6 gives 3 as a transient product in acid-catalyzed disproportionation of 6 into a mixture of tropone (4) and 1,3,5-cycloheptatriene (7) in chloroform containing water. Furthermore the existence of 3 in the latter reaction was confirmed by trapping with 4-phenyl-1,2,4-triazoline-3,5-dione to afford the [4+2]cycloadduct of the norcaradiene form of 3.
- Oda, Mitsunori,Okawa, Kazuya,Tsuri, Hitoshi,Kuroda, Shigeyasu
-
p. 795 - 800
(2007/10/03)
-
- Stereo- and regiocontrolled hydroxylation of oxyallyl [4+3] cycloadducts. A concise synthesis of hinokitiol
-
Stereo- and regioselective hydroxylation of 8-oxabicyclo[3.2.1]oct-6-en-3-ones was achieved by the action of (diacetoxyiodo)benzene in methanolic potassium hydroxide (the Moriarty oxidation). Subsequent double elimination afforded a convenient preparation of substituted tropolones, as exemplified in a three-step synthesis of hinokitiol (1).
- Lee, Jae Chol,Cho, Sung Yun,Cha, Jin Kun
-
p. 7675 - 7678
(2007/10/03)
-
- Tetrachlorocyclopentadienone O-Oxide, a Facile Oxygen-Atom-Transfer Reagent: The Disproportionation of Cycloalkyldioxyl Radicals
-
Photolysis of tetrachlorodiazocyclopentadiene (1) in oxygen-saturated hydrocarbon solvents results in the transient formation of tetrachlorocyclopentadienone O-oxide (3). This rapidly decomposes, giving rise to products derived from oxidation of the hydrocarbons. Cyclopentane, cyclopentene, cycloheptane, cycloheptene, cycloheptatriene, and indene have been studied. Cycloheptatriene and indene gave only low yields of tractable products, but the others gave the corresponding ketones and secondary alcohols as the major products. Although yields varied considerably, the ketone and alcohol products were always obtained, within experimental error, in a 1 : 1 molar ratio. This observed product ratio supports the disproportionation of cycloalkyldioxyl radicals as a crucial step.
- Dunkin, Ian R.,McCluskey, Adam
-
p. 1397 - 1400
(2007/10/03)
-
- Reactions of O,O'-disubstituted benzonitrile oxides with 8-azaheptafulvenes
-
In the reaction of O,O′-disubstituted benzonitrile oxides (If-h) with 8-p-tolyl-8-azaheptafulvene (2) in cyclohexane there is a competition between attack by the nitrile oxides on the C=N moiety [to give a mixture of equilibrating "fused" and "spiro" adducts (3/4)] and on the C2-C3 double bond (to give 12 which isomerizes to 13) of 2. Site selectivity was highly enhanced by carrying out the reaction in polar solvents. Only the attack on the C=N moiety was observed in the polar and protic methanol. A synthesis of 13 by a mild new procedure of decomplexation of the tricarbonyliron complex of 12 (i.e., 15) is described.
- Freccero, Mauro,Gandolfi, Remo,Amade, Mirko Sarzi
-
p. 453 - 468
(2007/10/03)
-
- 1,3-Dipolar Cycloaddition Reactions of 2,4,6-Cycloheptatrien-1-imines with Benzonitrile Oxides Leading to 1,2,4-Oxadiazaspiroundeca-2,6,8,10-tetraenes
-
1,3-Dipolar cycloaddition reactions of N-aryl-2,4,6-cycloheptatrien-1-imines with p-substituted benzonitrile oxides afforded -type cycloadducts in considerable yields.A study of the substituent effect on the reaction rate revealed that the reactions proceeded through nucleophilic reactions of imines to nitrile oxides.Thermal isomerizations and addition reactions of the adducts showed that the contribution of a valence isomerization between cycloheptatriene and norcaradiene lay to the side of the cycloheptatriene form.A comparison of the UV spectra between the adduct and its derivative, which was reduced by catalytic hydrogenation, implies that the spiroconjugation between cycloheptatriene and a five-membered heterocyclic moiety causes a shift of the equilibrium.
- Ito, Kazuaki,Saito, Katsuhiro
-
p. 3539 - 3548
(2007/10/03)
-
- Applications of enzymes in the synthesis of bioactive polyols
-
Cyclopentadiene, benzene and cycloheptatriene have been transformed to the functionalized meso-diols.The resulting meso-diols or their corresponding meso-diacetates have been subjected to enzymatic asymmetrizations using enzymes, particularly lipases, in organic or aq. media.Examples of the use of the resulting aracemic products in the synthesis of a variety of polyols of biological interest have been reviewed.
- Johnson, Carl R,Adams, Joseph P,Bis, Scot J,Jong, Randall L De,Golebiowski, Adam,et al.
-
p. 140 - 144
(2007/10/02)
-
- EFFECT OF DELOCALIZATION OF ?-ELECTRON DENSITY ON THE BASICITY OF MONO- AND POLYCYCLIC KETONES, FROM THE DATA OF 17O NMR SPECTROSCOPY
-
By means of 17O NMR spectroscopy a large series of mono- and polycyclic aromatic ketones was studied in DMSO medium.A linear correlation between chemical shifts of the carbonyl group in 13C and 17O NMR spectra was found.We have established that the 17O chemical shift in ketones in their ordinary state reflects a tendency for reduction in basicity with decrease of the electronic density at the oxygen atom.It is shown that the basicity of aromatic ketones is affected by the degree of delocalization of ?-electron density both in the neutral and in the protonated form, and also by steric effects.
- Negrebetskii, Vad. V.
-
p. 1436 - 1440
(2007/10/02)
-
- Enzymatic asymmetrization in organic media: Synthesis of unnatural glucose from cycloheptatriene
-
Pseudomonas cepacia lipase mediated asymmetrization of a meso-3-O-protected 6-cyclohepten-1,3,5-triol using isopropenyl acetate as solvent produced optically pure monoacetate 2. Elaboration of 2 by stereoselective oxygenation of the ring system using the Rubottom reaction, diastereoselective reduction, and osmium tetroxide catalyzed cis hydroxylation lead to cycloheptanehexaol derivative 20. This cyclic polyol was transformed into an allylic alcohol which was subjected to ozonolysis followed by NaIO4 diol cleavage to give L-glucose.
- Johnson, Carl R.,Golebiowski, Adam,Steensma, Darryl H.
-
p. 9414 - 9418
(2007/10/02)
-
- Anodic oxidation of cycloheptatriene systems and its application to the synthesis of non-benzenoid aromatic compounds
-
Anodic oxidation of cycloheptatrienes has been found to be one of the most powerful key tools for the preparation of a variety of non-benzenoid aromatic compounds such as tropylium salts, tropones, tropolones, 2H-cyclohepta[b]furan-2-ones, and azulenes.
- Shono, Tatsuya,Nozoe, Tetsuo,Maekawa, Hirofumi,Yamaguchi, Yoshihide,Kanetaka, Shinya,Masuda, Haruhisa,Okada, Toshio,Kashimura, Shigenori
-
p. 593 - 603
(2007/10/02)
-
- Synthesis and Molecular Structure of Hexacarbonyl(tropene)diiron
-
Molecular structure of hexacarbonyl(tropene)diiron has been investigated by X-ray diffraction studies.
- Morita, Noboru,Kabuto, Chizuko,Asao, Toyonobu
-
p. 1677 - 1678
(2007/10/02)
-
- The reaction of tropone and tropilidene derivatives with palladium acetate in benzene
-
Reaction of tropone or tropilidene derivatives with palladium acetate in benzene gave the following results.Tropone yielded 2-phenyltropone and 2,7-diphenyltropone. 2-Methoxytropone gave 2-methoxy-7-phenyltropone.Tropilidene yielded 1-phenyltropilidene but 7-methoxytropilidene gave tropone.
- Saito, Katsuhiro
-
p. 265 - 268
(2007/10/02)
-
- ANODIC TRANSFORMATION OF CYCLOHEPTATRIENE TO TROPONE AND TROPOLONE
-
Cycloheptatriene (CHT) has been directly transformed to 7-methoxycycloheptatriene (7-MCHT), an equivalent compound to a tropolium salt, by the anodic oxidation of CHT in methanol.The further anodic oxidation of 3-MCHT prepared from 7-MCHT has been found to be an effective method of synthesis of tropone and tropolone.
- Shono, Tatsuya,Nozoe, Tetsuo,Maekawa, Hirofumi,Kashimura, Shigenori
-
p. 555 - 558
(2007/10/02)
-
- Cleavage of the Oxygen Bridge in 8-Oxabicyclooctan-3-ones and -oct-6-en-3-ones by Trimethylsilyl Trifluoromethanesulfonate
-
The 8-oxabicyclooct-6-en-3-ones 1a-c react with trimethylsilyl trifluoromethanesulfonate/triethylamine (TMSOTf/NEt3) to give tropones.The bicyclic compounds 5, hydrogenated at the 6,7-double bond, are cleaved by TMSOTf/NEt3 to form 1,6-bis(trimethylsiloxy)-1,3-cycloheptadienes 6 and the double bond isomers 7a, 8e.Cycloheptenones are obtained by methanolysis of the trimethylsilyl dienol ethers.
- Foehlisch, Baldur,Sendelbach, Stefan,Bauer, Harald
-
-
- TROPOTHIONE. SYNTHESIS, SPECTRA AND CHEMICAL REACTIONS
-
Tropothione has been effectively synthesized as unstable red crystals and fully characterized by various spectroscopies as well as pKa and dipole moment measurements together with chemical characterization reactions.The properties of tropothione was revealed to differ considerably from those of tropone.
- Machiguchi, Takahisa,Otani, Hiroyuki,Ishii, Yukiko,Hasegawa, Toshio
-
p. 203 - 206
(2007/10/02)
-
- DIELS-ALDER CYCLOADDITION REACTIONS OF CYCLOPROPENONE KETALS DUAL PARTICIPATION IN INVERSE ELECTRON DEMAND (LUMOdiene CONTROLLED) AND NORMAL (HOMOdiene CONTROLLED) DIELS-ALDER REACTIONS. APPROACHES TO THE PREPARATION OF TROPONES
-
Diels-Alder cycloadditions of the cyclopropenone ketal 1 with representative electron-deficient, electron-rich and neutral dienes are presented.The results observed are consistent with the potential for the strained olefin of the cyclopropenone ketal to exhibit accelerated participation in both inverse electron demand (LUMOdiene controlled) and normal (HOMOdiene controlled) Diels-Alder reactions.Approaches to the introduction of cycloheptatrienones, tropones, based on the room temperature and pressure-promoted Diels-Alder reactions of the cyclopropenone ketal 1 are presented.
- Boger, Dale L.,Brotherton, Christine E.
-
p. 2777 - 2785
(2007/10/02)
-
- STEREOSELECTIVITY IN THE DIELS-ALDER REACTIONS OF TROPYLIUM ION
-
New Diels-Alder reactions of tropylium ion are studied, and the observed stereoselectivities suggest that solvent effects determine the steric course of these reactions.
- Clemans, George B.,Dobbins, Michael A.
-
p. 387 - 390
(2007/10/02)
-
- A FACILE AND EFFICIENT PREPARATION OF TROPONE FROM DI-7-CYCLOHEPTATRIENYL ETHER USING TRIFLUOROACETIC ACID AS A CATALYST
-
Tropone is prepared by an improved method in high yields without troublesome workup processes.Thus, di-7-cycloheptatrienyl ether is treated at room temperature with a small amount of trifluoroacetic acid as a catalyst.
- Machiguchi, Takahisa
-
p. 1021 - 1026
(2007/10/02)
-
- CYCLOADDITIONSREAKTIONEN DES HEPTAFULVALENS
-
The cycloaddition reactions of heptafulvalene with singulet oxygen, CSI and PTD have been investigated
- Erden, Ihsan,Kaufmann, Dieter
-
p. 215 - 218
(2007/10/02)
-
- PHOTOCHEMISTRY OF BICYCLIC δ-THIA-α,β-UNSATURATED KETONES A VINYLKETENE MECHANISM
-
Photolyses and pyrolyses of bicyclic δ-thia-α,β-unsaturated ketones (8) and (1a) were investigated.Experimental and spectroscopic evidences support a vinylketene mechanism both for photolysis and pyrolysis.
- Miyashi, Tsutomu,Suto, Nobukazu,Yamaki, Takayuki,Mukai, Toshio
-
p. 4421 - 4424
(2007/10/02)
-
- CYCLOADDITION REACTIONS OF 4,6-DIPHENYLTHIENO-1,2,5-OXADIAZOLE AND -1,2,5-THIADIAZOLE WITH 6,6-DIPHENYLFULVENE AND TROPONE
-
4,6-Diphenylthieno-1,2,5-oxadiazole (1) reacts as a thiocarbonyl ylide with 6,6-diphenylfulvene to give the exo- adduct via a stereoselective and regiospecific cycloaddition.The exo-adduct undergoes thermal cleavage of the oxadiazole ring to nitrile and nitrile oxide moieties which can be trapped as 1,3-cycloadducts to the fulvene and dimethyl acetylenedicarboxylate.The reaction of 4,6-diphenylthieno-1,2,5-thiadiazole (2) with the fulvene affords a mixture of analogous exo- and endo-adducts which are subject to a retro-cycloaddition reaction.On the other hand, 1 reacts with tropone to give the corresponding adduct which is susceptible to a retro-cycloaddition reaction.However, 2 did not react with tropone.
- Tsuge, Otohiko,Takata, Toshiaki,Noguchi, Michihiko
-
p. 1031 - 1034
(2007/10/02)
-
- The Sensitized Photooxidation of Methoxycycloheptatrienes. The Synthesis of α-, β-, and γ-Tropolones
-
The sensitized photooxidation of 7-methoxycycloheptatriene (7-methoxytropilidene) afforded cycloadduct (2), tropone, benzaldehyde and their 2-methoxy derivatives.Thermal isomerization of 2 followed by the treatment with alumina yielded 4-methoxytropone.The photooxidation of 1-methoxytropilidene gave 4-hydroxytropone and o-methoxybenzaldehyde, and the photooxidation of 3-methoxytropilidene followed by the treatment with triethylamine afforded 3-methoxytropone, tropone, and o-methoxybenzaldehyde.Characterization of the products and the mechanisms of the reactions are discussed.
- Yagihara, Morio,Kitahara, Yoshio,Asao, Toyonobu
-
p. 236 - 238
(2007/10/02)
-
