Nickel-Catalyzed Reductive Borylation of Enaminones via C(sp2)–N Bond Cleavage

The cleavage and transformation of alkenyl C­(sp2)–N bonds is a significant synthetic challenge. Herein we described an unprecedented nickel-catalyzed reductive borylation of enaminones to synthesize β-ketone boronic esters. Notably, B2pin2 played the dual role in this process, and water served as a hydrogen source, which was transferred to target products. The air-stable nickel catalyst was applied to the cleavage of alkenyl C­(sp2)–N bonds, concomitant with the reductive process of the alkenyl boronic ester intermediates, on the basis of the mechanism study.