Optically active bicyclic lactone prepn. - from optically active pseudoesters of hydroxy -substd. lactone

摘要

An optically active lactone of formula (I) (where the junction between rings A and B is cis; X is H and R is benzyl) is prepd. by reacting a racemic hydroxy-lactone of formula (II) ((I) where rings A and B are cis-linked and X is OH) with optically active (-)-menthol, (-)-borneol, (-)-pantolactone or (+)-pantolactone to give the corresponding optically active pseudoesters of formula (III) (I; X is -OR1; R1 is a residue corresponding to the alcohol used), separating these pseudoesters from each other by fractional crystallization, hydrolysing the pseudoester of the desired antipode to the optically active cpd. of formula (II), and reducing this optically active cpd. (pref. with NaBH4 or KBH4). (I) is an inter. for (+)-biotin and its derivs.