Photochemical and Acid-Catalyzed Rearrangements of 4-Carbomethoxy-4-methyl-3-(trimethylsilyl)-2,5-cyclohexadien-1-one

The synthesis of 4-carbomethoxy-4-methyl-3-(trimethylsilyl)-2,5-cyclohexadien-1-one (1) in 60% overall yield from benzaldehyde is described. Irradiation (366 nm) of 1 in benzene solution gave products of type A photorearrangement; e.g., diastereomers of the 4-(trimethylsilyl)- and 5-(trimethylsilyl)bicyclo[3.1.0]hex-3-en-2-ones 8 and 9. Bicyclohexenones 9a and 9b could not be isolated, but underwent acid-catalyzed protiodesilylative rearrangements on attempted chromatography (silica gel) to give a 1:1 mixture of (E)- and (Z)-4-(carbomethoxymethylmethylene)cyclopent-2-en-1-ones 12 and 13. Irradiation (366 nm) of either 12 or 13 resulted in photoisomerization to a photostationary state that was also a 1:1 mixture. Irradiation of 8a or 8b gave equivalent mixtures of phenols 14 and 15 by way of the type B oxyallyl zwitterion 17. The available experimental evidence suggests that both 9a and 9b undergo regiospecific photorearrangement to phenol 16 with no trace of 3-methyl-4-carbomethoxyphenol (19), the product of ipso substitution of the Me(3)Si group at C(4). Phenol 15 was isolated in 65% yield from the photoreaction of 1 in benzene with 20 equiv of CF(3)CO(2)H. The acid-catalyzed rearrangement of 1 to 3-carbomethoxy-4-methylphenol (21) occurs in 91% yield by way of CO(2)Me group rearrangement to C(3) to give the Me(3)Si-stabilized carbocation 23.     

4- Hydroxy-3, 5-di-tert -butylbenzalchloride in the synthesis of sterically hindered phenols

Conclusions We have obtained 4-hydroxy-3,5-di-tert-butylbenzalchloride by reacting 4-hydroxy-3, 5-di-tert-butylbenzaldehyde with thionyl chloride, and have studied its reactions with alcohols, phenols, and amines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 902–904, April, 1968.     

Synthesis of novel phosphorus-containing sterically hindered phenols by the reaction of diphenyl (3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)methylphosphonate with phenols

Diphenyl (3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate was oxidized to the corresponding methylidenequinonoid derivative. The addition of phenols to the exocyclic double bond of this compound gave phosphonates with two phenol moieties.     

Spirocyclohexadienones. 5. Synthesis of 2-R-7a-methyl-3-(spirocyclohexa-2,5-dien-4-one)perhydro-1-indolines

2-R-7a-Methyl-3-(spirocyclohexa-2,5-dien-4-one)perhydro-1-indolines were obtained by the reactions of 1-(4-ethoxyphenyl)-2-methylcyclohexanol with nitriles (RCN) in dichloromethane in the presence of concentrated sulfuric acid.     

Synthesis of 3-R2-4-R1-acetyl-(ethoxycarbonyl)-6-hydroxy-6-methylindazoles

It was discovered that functionally substituted tetrahydroindazoles can be aromatized by the action of sulfur. Previously unknown 3-R²-4-R¹-5-acetyl(ethoxycarbonyl)-6-methylindazoles were obtained. The products from aromatization cannot be obtained if a nitro group is introduced or one heteroatom in the substrate is replaced by oxygen.N. G. Chernyshevskii Saratov State University, Saratov, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 757–759, June, 1999.     

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.     

Microwave-assisted synthesis of sterically hindered 3-(5-tetrazolyl)pyridines

Sterically hindered 2,4-disubstituted 3-(5-tetrazolyl)pyridines were efficiently prepared from the corresponding nicotinonitriles using microwave technology.     

Synthesis of 4-R-3-(4-R1-5-R2-1,2,3-triazol-1-YL)furazans. 1. Azidofurazans in 1,3-dipolar cycloaddition reactions with substituted acetylenes

The 1,3-dipolar cycloaddition of azidofurazans to substituted acetylenes has been studied and substituted 3-(1,2,3-triazol-l-yl)furazans have been synthesized.N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913, Russia; e-mail: mnn@cacr.ioc.ac.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 100–110, January, 2000.     

On triazoles. V. Synthesis of 1- and 2-R1-3-R2,R3-amino-5-amino-1,2,4-triazoles

The correct isomeric and tautomeric structure of different 1- and 2-R¹-3-R²,R³-amino-5-amino-1,2,4-triazole derivatives prepared from the corresponding N-cyano-N'-R²,R³-S-methyl-isothioureas and the corresponding hydrazines was proved with the help of their ir, uv, ¹H-nmr and ¹³C-nmr spectra as well as the uv spectra of the Schiff bases of an isomeric pair.     

Synthesis,spectroscopic and redox properties of nickel(II) salicylaldimine complexes containing sterically hindered phenols

The preparation and spectroscopic characterization of a series of new bis[N-(2,6-di-t-butyl-1-hydroxyphenyl)salicylaldiminato]nickel(II) complexes, [Ni(L^X)₂], bearing one or two OH and MeO substituents on the salicylaldehyde moiety, as well as radical species generated from these compounds by the oxidation with PbO₂, are reported. The [Ni(L^X)₂] chelates, which appear to be tetrahedral in the solid state and in dioxane solution, are converted into a square-planar configuration in non-donor solvents. The OH-substituted complexes, unlike their MeO analogues, form six-coordinate adducts in pyridine, DMF and DMSO. These new compounds, unlike their analogues with electron-withdrawing substituents (Cl, Br, NO₂), are easily oxidized by PbO₂ to produce Ni^II-stabilized phenoxy radicals in which the unpaired electrons are delocalized over the ligand and do not couple with the second radical center. No e.s.r. signals were observed that could be attributed to a M = ±2 transition of the triplet state biradicals.     

5-二氰亚甲基-4-二环丙亚甲基-3-[1-(2,5-二甲基-3-呋喃基)亚乙基]四氢呋喃-2-酮的合成

报道俘精酸酐类化合物(E/Z)4-二环丙亚甲基-3-[1-(2,5-二甲基-3-呋喃基)亚乙基]四氢呋喃-2,5-酮的拆分,及(E)和(Z)-5-二氰亚甲基-4-二环丙亚甲基-3-[1-(2,5-二甲基-3-呋喃基)亚乙基]四氢呋喃-2-酮4(E)和4(Z)的合成,并对它们的光致变色特性进行了初步研究。