Photocatalytic Amine-Promoted Selective Hydrochlorination and sp³ C–O Acylation of Alkyne-Tethered Methyl Ethers with Aldehydes

We present a photoredox and alkylamine-assisted approach for the selective hydrochlorination and acylation of sp³ C-O bonds in alkynyl methyl ethers using aldehydes. This method leverages a cascade of radical processes─including chlorine radical addition, hydrogen atom transfer, <i>in situ</i> imine radical addition, and spin-center shift─to enable selective hydrochlorination of alkynes and the spontaneous cleavage of sp³ C-O bonds. The transformation accommodates a broad range of internal alkyne-tethered ethers and aldehydes, providing an efficient and streamlined pathway to chloro-alkenyl ketones. Utilizing only a photocatalyst, chloride, and propylamine under light irradiation, this strategy offers a practical and complementary alternative to previous sp³ C-O cleavage protocols.