Asymmetric Direct Vinylogous Aldol Reaction of Furanone Derivatives Catalyzed by an Axially Chiral Guanidine Base

摘要

The aldol reaction is one of the most ubiquitous in synthetic organic chemistry. The vinylogous extension of this fundamental C-C bond-forming reaction to nucleophilic components, namely the vinylogous aldol (VA) reaction, has also been intensively investigated, as it provides efficient access to highly functionalized S-hydroxy carbonyl compounds that contain a double bond. In particular, the utilization of 2-silyloxyfuran as the vinylogous nucleophile has attracted much attention because the reaction affords γ-substituted butenolides, an important structural motif in naturally occurring products and biologically active compounds. In this context, the development of the enantioselective catalysis of the VA reaction using 2-silyloxyfuran continues to be a substantial challenge in organic synthesis, and several excellent approaches have been reported to date.