Vicinally substituted cyclopentenes and cyclopentenones from (±)-7,7-dichlorobicyclo[3.2.0]hept-2-en-6-one

Abstract

Solvolysis of (±)-7,7-dichlorobicyclo[3.2.0]hept-2-en-6-one in a mixture of tert-butyl alcohol with water and triethylamine, followed by successive treatment with K 2 CO 3, NaBH 4, and CH 2 N 2, gave methyl 2-(hydroxymethyl)cyclopent-2-ene-1-carboxylate which was subjected to hydride reduction, epoxidation, trichloroacetimidation, and acetylation. Allylic oxidation of methyl 2-(acetoxymethyl)cyclopent-2-ene-1-carboxylate with the chromium(VI) oxide-3,5-dimethylpyrazole complex afforded methyl 2-(acetoxymethyl)-4-oxocyclopent-2-ene-1-carboxylate, and methyl (1R∗,2R∗,5R∗)-1-(hydroxymethyl)-6-oxabicyclo[3.1.0]-hexane-2-carboxylate was converted into a building block for the synthesis of deoxyentecavir and sarcomycine methyl ester.