Regioselectivity of the Cyclization of Dithiol Esters. An Alternative Route to Cyclic γ-Substituted β-Keto Thiolesters

Abstract

Recently, we described the condensation of dithiol esters under mild basic conditions giving cyclic β-keto thiolesters¹. When applied to unsymmetrically substituted dithiol esters of type 1, the cyclization is expected to proceed with complete regio-selectivity resulting in the formation of β-keto thiolesters possessing general formula 2, as is observed for the closely related Dieckmann condensation of di-0-esters.² We wish to report experimental results which demonstrate the validity of this expectation. This communication also describes a facile skeletal rearrangement of α-substituted β-keto thiolesters 3 leading directly to compounds of type 2.³ The only existing method for