Intramolecular alkynylogous mukaiyama aldol reaction starting from bicyclic alkanones tethered to alkynyl esters: formal total synthesis of (+/-)-hamigeran B.

tert-Butyldimethylsilyltriflate (TBSOTf)/NEt(3) treatment of alkynyl esters tethered to bicycloalkanones led to tricyclic allenoates with total diastereoselectivity for the ring junction. The allenoates result from an intramolecular alkynylogous Mukaiyama aldol reaction promoted by a TBSOTf/NEt(3) dual activation, with key intermediates of silylalkynylketene acetals. This novel methodology was illustrated by a formal total synthesis of (+/-)-hamigeran B.