Selective reduction of alkyne compounds

摘要

A process is provided for the preparation of cyclohexene derivatives of general formula I or II: in which the substituents R1 and R2 independently of one another are defined as follows: R2 is OH or a protective group convertible to a hydroxyl group by hydrolysis, R3 and R4 are hydrogen or C1-C4-alkyl, and R5 is hydrogen or C1-C4-acyl, by the reduction or alkyne compounds of general formula III or IV: wherein the reducing agent used is at least one salt of hyposulfurous acid or hydroxymethanesulfinic acid or a mixture of at least one salt of hyposulfurous acid and at least one salt of hydroxymethanesulfinic acid.