Photo-induced dehalogenative deuteration and elimination of alkyl halides enabled by phosphine-mediated halogen-atom transfer†

Abstract

Dehalogenative deuteration of organic halides is an efficient and straightforward method for incorporating deuterium atoms at specific locations within target molecules. However, utilizing organic halides in photoredox chemistry, particularly unactivated alkyl halides, presents challenges due to their low reduction potentials. In this work, we present a general and effective photoinduced dehalogenative deuteration method for a diverse array of alkyl halides, employing D₂O as an economical source of deuterium. The use of Cy₃P as a halogen-atom transfer reagent facilitates the dehalogenation of alkyl halides. This method demonstrates a broad scope, with over 70 examples, and shows excellent tolerance for various alkyl halides. The precise dehalogenation of complex alkyl halides highlights the potential of this protocol for late-stage dehalogenative deuteration of natural product derivatives and pharmaceutical compounds. Additionally, the dehalogenative elimination of unactivated alkyl halides can also be achieved by integrating photoredox and cobalt catalysis using the same halogen-atom transfer agents.