Axial chirality reversal and enantioselective access to Si-stereogenic silylallene

Summary

Selective hydrosilylation of 1,3-enynes is challenging because of the competing 1,2-, 1,4-, 4,3-hydrosilylation and sequential double hydrosilylation. Herein, we report a Cu-catalyzed enantioselective 1,4-hydrosilylation of 1,3-enynes. The reaction is amenable not only to preparing chiral silylallenes that possess axial chirality but also to preparing chiral silylallenes that possess both an axial chirality and a chirality at the silicon stereogenic center. Moreover, we disclose that the axial chirality can be reversed in the chirality construction reaction at the silicon stereogenic center without the change of chiral ligand. The combined experimental and density functional theory (DFT) calculations suggest the involvement of a dynamic kinetic asymmetric transformation (DYKAT) of two allenyl copper intermediates.