Alkynylation of Epoxides with Alkynylalanes at the More Hindered Carbon

Significance

Epoxides are important building blocks in organic synthesis; they are relatively readily available in enantiopure forms. This is the first general method for the addition of carbanions to the more hindered position of trisubstituted epoxides. The nucleophilic ring opening by aluminates results in the completely stereoselective formation of an all-carbon quaternary center in a chemoselective fashion. This approach allows a simple stereoselective construction of relatively complex carbon frameworks.