Phosphonium Ylide as Hydrogen Atom Transfer Catalyst Platform Based on Carbon-Centered Radical with High Structural Tunability.

Hydrogen atom transfer (HAT) catalysis has emerged as a powerful tool for the C-H functionalization of organic molecules. While several HAT catalysts based on heteroatom-centered radicals have been developed, the study of the catalytic use of carbon-centered radicals responsible for the HAT process has been underexplored. Herein, we introduce phosphonium ylides as a HAT catalyst platform based on a carbon-centered radical. The readily available and highly tunable features of this platform have allowed the systematic study of the effect of the catalyst structure on its physical properties. The ability of these ylides as practical HAT catalysts has been demonstrated in the photoinduced C-H alkylation of various small organic molecules, including alcohols, heterocycles, and primary amines.