Stereoselective Synthesis of Fully-Substituted Acrylonitriles via Formal Acylcyanation of Electron-Rich Alkynes.

A Sc(OTf)3-catalyzed formal acylcyanation of electron-rich alkynes for the efficient synthesis of fully-substituted acrylonitriles is described. By means of alkyne carbonyl metathesis, the reaction features mild conditions, high regio- and stereoselectivity, and a broad scope. The strong preference of the nitrile group for inward rotation in the torquoselective ring opening of the oxetane intermediate determines the remarkable Z selectivity of this process.