Ni‐Catalyzed Enantioselective Reductive Cyclization/Amidation and Amination of 1,6‐Enynes and 1,7‐Enynes

Abstract

Transition‐metal‐catalyzed hydroamination of unsaturated hydrocarbons is an appealing synthetic tool for the construction of high value‐added chiral amines. Despite significant progress in the asymmetric hydroamination of alkenes, allenes, and 1,3‐dienes, asymmetric hydroamination of 1,6‐enynes or 1,7‐enynes remains rather limited due to the enormous challenges in controlling the chemoselectivity and stereoselectivity of the reaction. Herein, we report a Ni‐catalyzed chemo‐ and enantioselective reductive cyclization/amidation and amination of 1,6‐enynes and 1,7‐enynes using dioxazolones or anthranils as nitrene‐transfer reagents. This mild, modular, and practical protocol provides rapid access to a variety of enantioenriched 2‐pyrrolidone and 2‐piperidone derivatives bearing an aminomethylene group at the 4‐position in good yields (up to 83%) with excellent enantioselectivities (40 examples, up to 99% ee). Mechanistic experiments and density functional theory calculations indicate that the reaction is initiated by hydronickelation of alkynes followed by migratory insertion into alkenes, rather than by a [2+2+1] oxidative addition process of nickel to alkenes and alkynes.