Studies on the Metabolism of Unsaturated Fatty Acids. V. Isomerization of Thiol Esters of cis-2-Alkenoic Acids during Their Preparation and Alkaline Hydrolysis

Abstract

N-Acetylcysteamine and coenzyme A esters of cis-2-alkenoic acids have been found to undergo isomerization to the corresponding trans-isomers during their preparation by the mixed anhydride method and also during their alkaline hydrolysis. The isomerization might proceed by interaction of the free thiol group and the cis-double bond of 2-alkenoic thiol esters. The use of pyridine as a base and three or more equivalents of the mixed anhydride to the thiol compound prevented the formation of the trans-isomer. Addition of hydrogen peroxide during alkaline hydrolysis also prevented the isomerization completely.