Synthesis of hydroxy thiol esters from glycidol esters

Abstract

Glycidol palmitate and glycidol stearate reacted with thiolacetic and thiolbenzoic acids at 20°C, each giving a single hydroxy thiol ester in good yield, the 1- S analogues of 1,3-diacylglycerols. Further acylaton of the secondary hydroxyl groups led to tri-acid 1- S analogues of triacylglycerols. Partial acylation of mercaptoglycerol gave mixtures of products from which the 1- S-3- O-diacyl esters could be isolated by crystallisation. The S-acyl-to- O-acyl isomerisation of the diacyl compounds was not observed in hexane, but it could be induced in pyridine solution. The spontaneous, rapid sulphur-to-oxygen migration of acyl groups in energy-rich hydroxy thiol esters may depend on their ability to assume a 6-membered ring chair form as thermodynamically favoured intermediate in preference to other ring sizes.