α-Chiral Acetylenes Having an All-Carbon Quaternary Center: Phase Transfer Catalyzed Enantioselective a Alkylation of α-Alkyl-α-alkynyl Esters

摘要

Owing to the synthetic versatility and modularity of acetylenes, chiral building blocks bearing acetylene moieties are widely used as valuable intermediates, Accordingly, tremendous efforts have been devoted to the development of catalytic asymmetric approaches to enable facile access to these attractive materials. The asymmetric transition metal mediated addition of terminal acetylenes (asymmetric alky-nylations) to various prochiral electrophiles (Scheme 1, left), such as aldehydes, ketones, aldimines, and electron-deficient alkenes, as well as asymmetric additions to prochiral alkynyl substrates (Scheme 1, right), have been successfully adopted for this purpose.