Enantio‐ and Diastereoselective Copper‐Catalyzed Allylboration of Alkynes with Allylic <i>gem</i>‐Dichlorides
Andrea Chaves‐Pouso, Andrés M. Álvarez‐Constantino, Martín Fañanás‐Mastral
Abstract
Allylic gem-dichlorides are shown to be efficient substrates for catalytic asymmetric allylboration of alkynes. The method employs a chiral NHC-Cu catalyst capable of generating in a single step chiral skipped dienes bearing a Z-alkenyl chloride, a trisubstituted E-alkenyl boronate and a bis-allylic stereocenter with excellent levels of chemo-, regio- enantio- and diastereoselectivity. This high degree of functionalization makes these products versatile building blocks as illustrated with the synthesis of several optically active compounds. DFT calculations support the key presence of a metal cation bridge ligand-substrate interaction and account for the stereoselectivity outcome.