Stereoselective Reaction of Acylic Alkenes Enolate alkylation – Allylic strain

Click the structures and reaction arrows in sequence to view the 3D models and animations respectively

The only low energy conformation is the one with hydrogen eclipsing the double bond. The alkylation occurs via the less hindered face, with a stereoselectivity of 95%. Examine the interactive energy diagram for the starting enolate.

R. W. Hoffmann, Chem. Rev., 1989, 89, 1841–1860.