NEW ASPECTS OF DITHIO AND THIONO ESTERS

The field of dithio and thiono esters is expanding rapidly. Therefore emphasis is layed mainly on results obtained by the research group of the author. In agreement with theoretical considerations thiono esters are always more stable than dithio esters. In the preparation of dithio and thiono esters by thioly-sis slightly acidic conditions were found to be essential. The CH-acidity at the α-carbon of dithio and thiono esters with pKa values about 12 is comparable to that of classical CH-acidic compounds such as ace-toacetic ester. Dithiono and tetrathio malonates do not show the expected chemistry of malonic esters; the electrophile reacts preferentially at the sulfur atom,α,β-Unsaturated dithio and thiono esters have been prepared by Wittig-Horner reactions, by Peterson synthesis, and by aldol condensations, α,β-Acety1enic dithio and thiono esters were obtained for the first time. In the formation of thiopeptide bonds from α-amino dithio esters the racemization observed seems to be of fundamental importance. Dianions of dithio acids were found to condense with different electrophiles. © 1991, Taylor and Francis Group, LLC. All rights reserved.