Photochemical Asymmetric Palladium-Catalyzed Allylation Reaction: Expeditious Entry to Chiral 1,2-Amino Alcohols and 1,2-Diamines
Hui Xie, Haohua Chen, Uttam Dutta, Yu Lan, Bernhard Breit
Abstract
The construction of diverse alkyl amines is of importance in drug discovery and natural product synthesis. Herein, we report an efficient photoredox/palladium dual catalysis for the construction of protected 1,2-amino alcohols and 1,2-diamines via the asymmetric allylation of α-silyl amines with heteroatom-substituted allenes and 1,3-dienes. This protocol is characterized by its mild conditions, high regio- and enantioselectivities, and wide substrate scope, including aliphatic amines or N -heterocyclic substrates especially. Computational and experimental mechanistic studies indicate that the reaction proceeds through a sequence of oxidative addition of the Pd(0) catalyst by PPTS, allene insertion, outer-sphere radical substitution-type C–C bond formation, and reduction of Pd(I) by Ir(II). Thereinto, the outer-sphere radical substitution is the enantio- and regioselectivity determining step.