Palladium‐Catalyzed Alkyne Hydrocyanation toward Ligand‐Controlled Stereodivergent Synthesis of (E)‐ and (Z)‐Trisubstituted Acrylonitriles

Abstract

AbstractWe herein describe a palladium‐catalyzed hydrocyanation of propiolamides for the stereodivergent synthesis of trisubstituted acrylonitriles. This synthetic method tolerated various primary, secondary and tertiary propiolamides. The cautious selection of a suitable ligand is essential to the success of this stereodivergent process. Control experiments indicate the intermediacy of E‐acrylonitriles, which lead to Z‐acrylonitriles via isomerization. The density functional theory calculations suggests that the bidentate ligand L2 enables a feasible cyclometallation/isomerization pathway for the E to Z isomerization, while the monodentate ligand L1 inhibits the isomerization, leading to divergent stereoselectivity. The usefulness of this method can be demonstrated by the readily derivatization of products to give various E‐ and Z‐trisubstituted alkenes. In addition, the E‐ and Z‐acrylonitrile products have also been successfully employed in cycloaddition reactions.