Direct intermolecular C(sp3)-H amidation with dioxazolones via synergistic decatungstate anion photocatalysis and nickel catalysis: A combined experimental and computational study

The direct C(sp3)-H amidation is a highly desirable but challenging approach to construct C(sp3)-N bonds. Herein, we describe a new strategy combining photoredox-mediated hydrogen atom transfer (HAT) and transition-metal catalysis for intermolecular C(sp3)-H amidation of unactivated alkanes, ketones, ethers, amines, and aldehydes with dioxazolones. This protocol, employing synergistic tetrabutylammonium decatungstate (TBADT) anion photocatalysis and nickel catalysis, provides a practical approach to realize a direct intermolecular C(sp3)-H amidation with useful reactivity and site selectivity under mild conditions, which may be applied to the late-stage modification of complex molecules. A combined experimental and computational mechanistic study implies the formation of a key [W10O32]4--Ni(I) species under irradiation of UV-A. The unusual cooperative roles of [W10O32]4- anion and Ni(I) moiety are suggested in generating a C-centered radical from C(sp3)-H bond and an amido group from dioxazolone, respectively. Subsequently, the formation of a [W10O32]4--Ni(III) complex followed by a reductive elimination step is proposed to afford the desired amidation product.

Automated summary

This study describes a new strategy for the direct C(sp3)-H amidation using photoredox-mediated hydrogen atom transfer and transition-metal catalysis under mild conditions. The method provides good reactivity and site selectivity for the construction of C(sp3)-N bonds and can be applied to the late-stage modification of complex molecules.