α-Methylthiocarbonylation of Ketones. Generality and Regioselectivity

Abstract

Over the past few years, there have been several methods documented for the preparation of β-keto thiolesters^2,3. However, most of these methods have limited synthetic applicability due to either the requirement of rather specific starting substrates³, or operational complexity, often coupled with unsatisfactory yields². A more promising procedure was briefly examined by Demuynck and Thuillier², who demonstrated the feasibility of β-keto thiolester formation by the reaction of an enolate ion with S,S'-dimethyl dithiocarbonate. Of the three simple acyclic ketones examined, products were obtained in moderate yields of 30–70%. In continuation of our investigation of the synthetic utility of β-keto thiolesters³ and efficient method of preparation was required. We have studied the α-methylthiocarbonylation process with special attention to its improvement, general applicability and regioslectivity.