Enantioselective Organocatalytic Tandem Michael-Aldol Reactions:One-Pot Synthesis of Chiral Thiochromenes

摘要

Despite the fact that the chemistry of thiopyrans has been much less explored than that of the analogous pyrans,recently the interest in the sulfur-containing heterocycles has been significantly surged since a wide range of biological activities associated with the scaffold have been identified.For example,1-benzothiopyrans exhibit anti-inflammatory,anti-bacteria,anti-hyperplasia,anti-psychiatric,analgesic,and anti-cancer activities.Accordingly,the development of new and facile synthetic strategies to access such heterocycles is of considerable interest.Various methods for their preparation have been reported.However,survey of the literature reveals that these approaches involve multistep sequences;moreover,to date,to the best of our knowledge,only two studies of the asymmetric version for synthesis of the scaffold have been described using either optically pure starting material or a chiral auxiliary.