E‐Selective Radical Difunctionalization of Unactivated Alkynes: Preparation of Functionalized Allyl Alcohols from Aliphatic Alkynes

Abstract

AbstractRadical difunctionalization of aliphatic alkynes provides direct access to valuable multi‐substituted alkenes, but achieving a high level of chemo‐ and stereo‐control remains a formidable challenge. Herein a novel photoredox neutral alkyne di‐functionalization is reported through functional group migration followed by a radical‐polar crossover and energy transfer‐enabled stereoconvergent isomerization of alkenes. In this sequence, a hydroxyalkyl and an aryl group are incorporated concomitantly into an alkyne, leading to diversely functionalized E‐allyl alcohols. The scope of alkynes is noteworthy, and the reaction tolerates aliphatic alkynes containing hydrogen donating C─H bonds that are prone to intramolecular hydrogen atom transfer. The protocol features broad functional group compatibility, high product diversity, and exclusive chemo‐ and stereoselectivity, thus providing a practical strategy for the elusive radical di‐functionalization of unactivated alkynes.