Direct Stereoconvergent Allylation of Chiral Alkylcopper Nucleophiles with Racemic Allylic Phosphates

Abstract

Copper-catalyzed stereoconvergent allylation of chiral sp(3)-hybridized carbon nucleophiles with a racemic mixture of acyclic secondary allylic phosphates is reported. In the presence of a copper-catalyst complexed with chiral BenzP* ligand, tandem coupling reaction of vinyl arenes, bis(pinacolato)diboron, and racemic allylic phosphates provided beta-chiral alkylboronates possessing (E)-alkenyl moiety through a direct stereoconvergent allylic coupling with concomitant generation of a C(sp(3))-stereogenic center. A range of vinyl (hetero)arenes and secondary allylic phosphates bearing 1 degrees, 2 degrees, 3 degrees alkyl and phenyl alpha-substituents were suitable for the reaction, forming products with high enantioselectivities up to 95 % ee. Density functional theory calculations were conducted in detail to elucidate the origin of the observed regioselectivity of borylcupration and stereoconvergent (E)-olefin formation from racemic allylic phosphates.