?-Selective Aroylation of Activated Alkenes by Photoredox Catalysis.

ABSTRACT: Late-stage synthesis of ?,?-unsaturated aryl ketones remains an unmet challenge in organic synthesis. Reported herein is a photocatalytic non-chain-radical aroyl chlorination of alkenes by a 1,3-chlorine atom shift to form ?-chloroketones as masked enones that liberate the desired enones upon workup. This strategy suppresses side reactions of the enone products. The reaction tolerates a wide array of functional groups and complex molecules including derivatives of peptides, sugars, natural products, nucleosides, and marketed drugs. Notably, addition of 2,6-di-tert-butyl-4-methyl-pyridine enhances the quantum yield and efficiency of the cross-coupling reaction. Experimental and computational studies suggest a mechanism involving PCET, formation and reaction of an ?-chloro-?-hydroxy benzyl radical, and 1,3-chlorine atom shift.

SUBMITTER: Lei Z 

PROVIDER: S-EPMC6527503 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature