Abstract: New optically active cyclopentene-diol and the mono- or diacyl esters thereof and a process for converting a diacyl ester of cyclopent-1-en-3,5-diol to its monoacyl ester and/or its diol which comprises subjecting a diacyl ester of cyclopent-1-en-3,5-diol containing at least one of the optically active or inactive diacyl ester of trans-cyclopent-1-en-3,5-diol (trans-isomer) and diacyl esters of cis-cyclopent-1-en-3,5-diol (cis-isomer), to the action of a microorganism or enzyme having at least a selectivity in its rates of hydrolyzing the acyloxy group (R) configuration and the acyloxy group (S) configuration of said diacyl ester. These new compounds are valuable as starting materials for the preparation of prostaglandin or its analogues.

Abstract: A process for the preparation of 1,4-diacetoxycyclopent-2-ene, which comprises contacting a solution of 1,4-dibromocyclopent-2-ene in an inert organic solvent which is slightly soluble or insoluble in water, with an aqueous solution or suspension of at least one metal salt of acetic acid which is at least partially water-soluble, in the presence of a cationic surface-active compound.