Electrochemically induced transformation of 4(6)-dihalomethyl-4(6)-methylcyclohexa-2,5(2,4)-dien-1-ones into 4(2)-methyltropones

Electrochemical investigation of 4(6)-dihalomethyl-4(6)-methylcyclohexa-2,5(2,4)-dien-1-ones using cyclic voltammetry (CVA) and rotating disc electrode (RDE) methods has been performed. The reductive dehalogenation of cyclohexa-2,5(2,4)-dien-1-ones having a dihalomethyl substituent at the tertiary carbon atom was shown to proceed as a two-electron reductive elimination of the geminal halogen atoms with the intermediate formation of carbene and subsequent rearrangement of cyclohexadienone with the ring expansion to the corresponding 4- or 2-methylcyclohepta-2,4,6-trien-1-one.     

Electrochemical reduction of 4-methyl-4-(trichloromethyl)cyclohexa-2,5-dien-1-one

The properties of 4-methyl-4-(trichloromethyl)cyclohexa-2,5-dien-1-one which contains the trichloromethyl substituent at a quaternary carbon atom have been studied by cyclic voltammetry, rotating disk electrode voltammetry, and preparative electrolysis. Reductive dehalogenation involves initial two-electron reductive elimination of one of the geminal chlorine atoms followed by consecutive addition of proton, simultaneous elimination of the two residual halogen atoms to form carbene, and rearrangement of cyclohexadienone into the corresponding 4-methylcyclohepta-2,4,6-trien-1-one.     

Redox troponization of (η5-cyclopentadienyl)(η4-4-menthyl-4-exo-trichloromethylcyclohexa-2,5-dien-1-one)rhodium as a novel approach to the synthesis of metal-coordinated nonbenzenoid aromatics of the tropone seriesas a novel approach to the synthesis of metal-coordinated nonbenzenoid aromatics of the tropone series

The possibility of redox troponization of a gem-polyhalomethylated semiquinoid system, π-coordinated to a metal atom, was shown in relation to the reaction of (η⁵-cyclopentadienyl)(η⁴-4-menthyl-4-exo-trichloromethylcyclohexa-2,5-dien-1-one)rhodium with Pd(PPh₃)₄. The reaction occurs with retention of the metal coordination affording a sevenmembered organometallic derivative of the nonbenzoid aromatic series, namely, (η⁵-cyclopentadienyl)(η⁴-4-chloro-5-menthylcyclohepta-2,4,6-trien-1-one)rhodium, whose structure was established by means of elemental analysis, NMR, and mass-spectral data. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1255–1256, June, 1998.     

Control of photoreactions of eight membered ring di- and trienones in a crystalline inclusion complex with optically active 1,6-DI(o-Chlorophenyl)-1,6-diphenylhexa-2,4-diyne-1,6-diol

By complexing with the title host compound, flipping equilibrium of cycloocta-2,4,6-trien-1-one was frozen in one optical conformer as a 2:1 complex, which upon irradiation gave optically active bicyclo [4.2.0] octa-4,7-dien-2-one. Irradiation of a 1:2 complex of cycloocta-2,4-dien-1-one and the same host compound gave an optically active dimer, anti-tricyclo [8.6.0.0^2,9] hexadeca-7, 11-diene-3, 16-dione.     

A simple synthesis of 4-amino-6-methyl-1,1,1-trifluoro(trichloro)hepta-3,5-dien-2-ones and 2,2-dimethyl-6-trifluoromethyl-2,3-dihydro-4-pyridone

Treatment of 2,2-dimethyl-6-trifluoro(trichloro)methyl-2,3-dihydro-4-pyrones with ammonia gives 4-amino-1,1,1-trifluoro(trichloro)-6-methylhepta-3,5-dien-2-ones. Under similar conditions 1,1,1-trifluoro-2-hydroxy-6-methylhepta-2,5-dien-4-one and 6-chloro-1, 1,1-trifluoro-2-hydroxy-6-methylhept-2-en-4-one cyclize into 2,2-dimethyl-6-trifluoromethyl-2,3-dihydro-4-pyridone. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2263–2265, December, 1997.     

The mechanism of nitration of 2,4,6-trialkylphenols by nitrogen dioxide in solution

The apparent rate of reaction of 2,4,6-trialkylphenols with nitrogen dioxide in solution is that of a 6-nitrocyclohexa-2,4-dien-1-one to 4-nitrocyclohexa-2,5-dien-1-one isomerisation unless the 2- and 6-alkyl groups are sufficiently bulky when the rate limiting stage may involve reaction between the appropriate phenoxy radical and NO₂.     

Electrochemically induced transformation of 4-halomethyl-4-methylcyclohexa-2,5-dien-1-ones into 3,4-dimethylphenol

Electrochemical behavior of 4-halomethyl-4-methylcyclohexa-2,5-dien-1-ones and 2,6-dibromo-4,4-dimethylcyclohexa-2,5-dien-1-one was studied. Reductive dehalogenation of cyclohexa-2,5-dien-1-ones having a halogen atom at the neopentyl-like carbon atom gives the corresponding carbanion which undergoes anionic cyclopropyl-allyl rearrangement with subsequent addition of proton to form 3,4-dimethylphenol.     

Electrochemical study of the sequence of reductive dehalogenation of 2-bromo-5-dibromomethyl-4-dichloromethyl-4-methylcyclohexa-2,5-dien-1-one and its analogs

The electrochemical behavior of a series of halogen-containing cyclohexa-2,5-dien-1-ones at the glassy-carbon electrode in DMF was studied. The reductive dehalogenation of 2-bromo-5-dibromomethyl-4-dichloromethyl-4-methylcyclohexa-2,5-dien-1-one first results in the elimination of the carbonylallylic bromine atoms, then the carbonylic bromine atom is elimi-nated, and finally, the neopentylic chlorine atoms are eliminated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1558–1564, September, 2006.     

Explosive chemical transformations of 4-bromo-2,4,6-tri-tert-butylcyclohexa-2,5-diene-1-one in strong uniaxial compression

Conclusions The study of explosive transformations of 4-bromo-2,4,6-tri-tert-butylcyclohexa-2,5-dien-1-one in strong uniaxial compression demonstrated the dependence of the degree of conversion of the starting substance and total yield of products on the value of the explosion pressure. A chemical mechanism of the process which includes heterolysis of the C-Br bond was proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 137–140, January, 1989.     

Polymerization systems driven by aromatization energy: Anionic polymerization of 4-allylidene-2,6-dimethyl-2,5-cyclohexadien-1-one and spiro[2,5]octadienone derivatives

To investigate the polymerization systems driven by aromatization energy, 4-allylidene-2,6-dimethyl-2,5-cyclohexadien-1-one ( Ia ), 5,7-dimethyl-1-vinylspiro[2,5]octa-4,7-dien-6-one ( Ib ), 4,7-dimethyl-1-vinylspiro[2,5]octa-4,7-dien-6-one [ Ic ], 2-vinyl-2′-methylspiro[cyclopropane-1,4′-(1′-naphthalenone)] ( Id ), and 2-phenyl-2′-methylspiro[cyclopropane-1,4′-(1′-naphthalenone)] ( Ie ) were prepared and polymerized with sodium cyanide in N,N-dimethylformamide. Monomer Ia was highly polymerizable even at ?65°C. Monomers Ib–Ie also polymerized well, giving powdery polymers that were soluble in common solvents. All the polymerizations took place through the aromatization of the cyclohexadienone ring, suggesting that the aromatization energy is the driving force for the polymerization of these monomers.     

Study of the reaction of 4-chloromethylene-2,6-di-<Emphasis Type="Italic">tert</Emphasis>-butylcyclohexa-2,5-dien-1-one with the P(III) acids esters

The main stable products of the reactions 4-chloromethylene-2,6-di-tert-butylcyclohexa-2,5-dien-1-one with triethyl phosphite and ethyl diphenylphosphinite are the phosphorylated phosphorus ylides, 3,3′,5,5′-tetra-tert-butylstilbenequinone, and biphosphorylated sterically hindered phenols.     

Five new diterpenoids from the bark of Taiwania cryptomerioides

Five new diterpenoids, 11-hydroxyabieta-8,11,13-trien-7-one (1), 11,12,14-trihydroxyabieta-8,11,13-trien-7-one (2), 6beta,7alpha-diacetoxyroyleanone (3), 7beta-hydroxymanoyl oxide (4), and 9alpha-hydroxyisopimara-8(14),15-dien-7-one (5) were obtained from the bark of Taiwania cryptomerioides. The structures of the new compounds 1-5 were elucidated on the basis of spectral analysis and chemical evidence.     

Studies on the Constituents of Ganoderma Lucidum

The methanolic extract of fruit bodies of cultivated Ganoderma lucidum was separated by silica gel column chromatography and preparative thin-layer chromatography to give ten compounds. On the basis of spectral analysis, chemical procedures and gas chromatography, d-mannitol (1), ergosta-7, 22-dien-3β-yl palmitate (2), ergosterol (3), ergosta-7, 22-dien-3β-ol (4), 5α-lanosta-7,9(11),24-trien-3β,26-diol (5), ergosterol peroxide (6), 24,25,26-trihydroxy-5α-lanosta-7,9(11)-dien-3-one (7), 5α-lanosta-7,9(11)-dien-3β,24,25,26-tetraol (8) and 8,9-epoxyergosta-5,22-dien-3β,15-diol (9) were identified. Among these compounds, 8,9-epoxyergosta-5,22-dien-3β,15-diol was first separated from Ganoderma lucidum.     

New version of redox-troponization — oxidative expansion of apara-semiquinoid ring in the reaction of 4-methyl-4-bromomethyl-2,5-cyclohexadien-1-one with tetrakis(triphenylphosphine)palladium

4-Methyl-4-bromomethyl-2,5-cyclohexadien-1-one reacts with Pd(PPh₃)₄ in benzene to give 4-methyl-2,4,6-cycloheptatrien-1-one. The reaction occurs as intramolecular carbometallation of the enone fragment of the starting dienone followed by rearrangement—dehydrometallation or involves a sequence of steps,viz., homolytic abstraction of the halogen atom, cyclization, recyclization, and dehydrogenation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1836–1837, September, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No. 95-03-09784) and the International Science Foundation (Grants MHW 000 and MHW 300).     

Unusual formation of 7-vinylcycloheptatriene derivatives in the catalytic cyclopropanation of cyclooctatetraene with diazocarbonyl compounds in the presence of rhodium catalysts

The reaction of cyclooctatetraene with methyl diazoacetate or diazoacetone in the presence of rhodium binuclear complexes gives, besides 9-substituted bicyclo[6.1.0]nona-2,4,6-trienes (mixture ofanti- andsyn-isomers, total yields 60–75%), isomeric β-(cyclohepta-2,4,6-trien-1-yl)acrylates or 4-(cyclohepta-2,4,6-trien-1-yl)but-3-en-2-one in 20–34% yields. In the case of methyl diazoacetate, a mixture ofE- andZ-isomers in a ratio of −3.5∶1 was obtained, while diazoacetone gave onlyE-isomer. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2204–2206, November, 1999.     

2,2′-Bifurylidene-5,5′-diones,Coumarins, 3a, 7a-dihydro-1H-inden-1-ones,and 5H-furo[3,2-b]pyran-5-ones from propyne and carbon monoxide

The [Co₂ (CO)₈]-catalyzed reaction between propyne and CO in acetone at 110° and 170 bar was re-investigated. There are five major products: (E)-3,4′-dimethyl-2,2′-bifurylidene-5,5′-dione ( 4 ), 3,5,8-trimethylcoumarin ( 8 ), 3a, 7a-dihydro-2,4,7,7a-tetramethyl-1H-inden-1-one ( 9 ), 2,6-dimethyl-5H-furo [3,2, -b]- pyran-5-one ( 11 ), and 2,7-dimethyl-5H-furo 3,2-b-pyran-5-one ( 12 ); of these, only one, 4 . had previously been recognized. In parallel experiments were obtained 2,6-dipentyl-5 H-furo[3,2-b]pyran-5-one ( 13 ), 2,7-dipentyl–5H-furo[3,2-b]pyran-5-one ( 14 ), 3a, 7a-dihydro-2,4,7,7a-tetrapentyl-1H-inden-1-one ( 15 ). And 3a, 7a-dihydro-2,4,6,7a-tetrapentyl-1H-inden-1-one ( 16 ) from hept-1-yne, and two further types of products from two atypical 1-alkynes: 3,6,9-tri(tert-butyl)-1-oxaspiro[4.4]nona-3,6,8-trien-2-one ( 20 ) from (tert-butyl)acetylene and the exo-dimer 21 of 2,5-bis(trimethylsilyl)cyclopenta-2,4-dien-1-one ( 22 ) from (trimethylsilyl)acetylene. Compounds 11,12 , and 20 were identified by X-ray analysis.     

Synthesis and structure of 2,4-di-tert-butyl-1-chloro-6-methyltricyclo[4.1.0.02,7]hept-4-en-3-one

The reaction of 2,6-di-tert-butyl-4-dichloromethyl-4-methylcyclohexa-2,5-dien-1-one with (Me₃Si)₂NNa yielded 2,4-di-tert-butyl-1-chloro-6-methyltricyclo[4.1.0.0^2,7]hept-4-en-3-one (substituted tropovalene). The structure of the title compound was established by¹H and¹³C NMR spectroscopy and X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1642–1645, September, 1997.     

Redox troponization of 4-methyl-4-dibromomethyl-2,5-cyclohexadien-1-one by the action of Pd(PPh3)4

Conclusions The feasibility of using gem-dihalomethyl-substituted cyclohexadienones in redox troponization reactions was shown in the case of the reaction of 4-methyl-4-dibromomethyl-2,5-cyclohexadien-1-one with Pd(PPh₃)₄, leading to the formation of 4-methy1-2,4,6-cycloheptatrien-1-one.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2345–2346, October, 1987.     

An efficient construction of C?N bond under catalyst-free and room temperature conditions

An efficient and facile process for the construction of C N bond from 1,6-conjugate addition reaction of 4-arylidene-2,6-di-tert-butylcyclohexa-2,5-dien-1-one (or substituted 3-[3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene]indolin-2-one) and substituted 1,2,3,4-tetrahydroisoquinoline (or substituted indoline) at room temperature was reported. The advantages of this reaction were catalyst-free, mild condition, broad substrate scope, and environmentally benign process.     

Synthesis of fluorine-containing 1,4-dioxa-2-azaspiro-[4.5]deca-2,6,9-trienes by reaction of polyfluorinated cyclohexa-2,5-dienones with nitrile oxides

4-Pentafluorophenoxy-, 4-nitro-, and 4-chloropentafluorocyclohexa-2,5-dien-1-ones and 3,4,5-tris-(pentafluorophenoxy)trifluorocyclohexa-2,5-dien-1-one react with some benzonitrile and acetonitrile oxides exclusively at the carbonyl group, leading to the formation of mixtures of diastereoisomeric fluorinated 1,4-dioxa-2-azaspiro[4.5]deca-2,6,9-trienes in good yield.