Intramolecular cyclization involving O-vinyl or O-vinylketoxime function in a number of pentacyclic triterpenoids in superbasic medium

28-Triphenylmethoxylup-20(29)-ene-2,3-dione dioxime and 18α(H)-oleanane-3β,19β,28-triol upon reaction with acetylene in superbasic medium KOH-DMSO undergo intramolecular cyclization with the formation of products containing 1,2,5-oxadiazole and tetrahydrofuran fragment, respectively.     

Ozonolysis of alkenes and study of reactions of polyfunctional compounds: LXVIII. Investigation of transformations of peroxide products of olefins ozonolysis treated with hydroxylamine hydrochloride

Hydroxylamine hydrochloride efficiently reduces peroxide products of olefins ozonolysis into carbonyl compounds. Depending on the substrate character, solvent, and the treatment conditions the arising aldehydes transformed along the route aldehyde→aldoxime→nitrile→ester into individual compounds or their mixtures, or give the corresponding acetals.     

Chiral blocks for the synthesis of cyclopentanoids from [2 + 2]-cycloadduct of dichloroketene and dimethylfulvene

Opening of the α,α-dichlorocyclobutanone ring in the [2 + 2]-cycloadduct of dichloroketene and dimethylfulvene with (+)-α-methylbenzylamine gave diastereoisomeric 2-dichloromethyl-5-isopropylidene-N-(α-methylbenzyl)cyclopent-3-ene-1-carboxamides, and hydrolysis of the latter at the dichloromethyl group afforded the corresponding bicyclic aminals which can be readily separated by chromatography on silica gel. The subsequent removal of the α-methylbenzylamine fragment via reduction and hydrolysis resulted in the formation of enantiomerically pure (-)- and (+)-6-(1-methylethylidene)-3,3a,6,6a-tetrahydro-1H-cyclopenta[c]-furan-1-ones.     

Cp2ZrCl2-catalyzed hydroalumination of norbornene derivatives withi-Bu2AlCl

Cp₂ZrCl₂-catalyzed (Cp = ⁵-C₅H₅) hydroalumination of substituted norbornenes withi-Bu₂AlCl was conducted, yielding higher cycloalkylhaloalanes with high yields.Institute of Organic Chemistry, Ural Branch, Russian Academy of Sciences, 450054 Ufa. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2791–2798, December, 1992.     

Synthesis of 1,6-anhydro-3-bromo-3,4-dideoxy-β-d-threo-hex-3-enopyranose

A preparative method for chemo- and stereoselective reduction of 3-bromolevoglucosenone into 1,6-anhydro-3-bromo-3,4-dideoxy--D-threo-hex-3-enopyranose using Zn(BH₄)₂ was developed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2455–2457, December, 1995.     

Cyclopropanation of betulonic acid and its methyl ester with dichlorocarbene generated under phase transfer catalysis conditions

The addition of dichlorocarbene generated under phase transfer catalysis conditions to the double bond of betulonic acid occurs stereoselectively and is accompanied by transformation of the carboxy group leading to the dichloromethyl ester and chloride of 3-oxo-20,29-(dichloromethano)lupan-28-oic acid. Together these products, the chloride of the starting betulonic acid is formed depending on the reaction conditions. The reaction of dichlorocarbene with methyl betulonate leads to the corresponding cyclopropane adduct in a quantitative yield. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2574–2578, November, 2005.     

13C NMR spectra of polycyclic compounds. Bicyclo[2.2.1]heptadiene tetramers

Comparison of experimental and calculated chemical shifts of carbon atoms in¹³C NMR spectra of two isomeric dodecacyclo[14.9.1.1^4,13.1^7,10.0^2,15.0^3,14.0^5,12.0^6,11.0^17,25.0^18,24.0^19,21. 0^20,24]-octacos-8-enes, bicyclo[2.2.1]heptadiene tetramers, confirmed theirexo-trans-exo-trans-exo-endo-andexo-trans-exo-trans-exo-exo-configurations. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2545–2547, December, 1998.     

Cyclopentenone blocks for 15-deoxy-Δ 12,14 -prostaglandin J2

Proceeding from the [2+2]-adduct of dichloroketene and dimethylfulvene a synthesis was developed of methyl (5Z)-7-(2,2-dimethyl-4-oxo-1-oxaspiro[2.4]hept-6-en-5-yl)hept-5-enoate, the key block in the new synthetic approach to 15-deoxy-Δ^12,14-prostaglandin J₂.     

Synthesis of (2<Emphasis Type="Italic">S</Emphasis>,3<Emphasis Type="Italic">S</Emphasis>,4<Emphasis Type="Italic">S</Emphasis>)-2,3-<Emphasis Type="Italic">O</Emphasis>-isopropylidene-4-(methoxycarbonylmethyl)cyclopentan-1-one

(2S,3S,4S)-2,3-O-Isopropylidene-4-(methoxycarbonylmethyl)cyclopentan-1-one was synthesized starting from D-ribose through methyl (Z)-3-(5-acetyl-2,2-acetoxyacetyl-2,2-dimethyl-1,3-dioxolan-4-yl)prop-2-enoate which was subjected to cyclization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, followed by decarboxylation.