Merging Distal Alkynyl Migration and Photoredox Catalysis for Radical Trifluoromethylative Alkynylation of Unactivated Olefins

Abstract

Disclosed herein is a novel, redox-neutral protocol for the visible-light-induced radical alkynylation of unactivated olefins. The intramolecular migration of an alkynyl group, by cleaving an inert C-C σ bond, is realized for the first time. A wide range of synthetically useful trifluoroethylated linear alkynes are readily obtained under mild reaction conditions.

Electrochemical Alkynyl/Alkenyl Migration for the Radical Difunctionalization of Alkenes

“…Based on the above experimentalr esults and previous reports, [9,10,15] ap lausible mechanism for this electrochemical radical migration reaction was proposed in Scheme 8. First Scheme6.Follow-upc hemistry.…”

“…In the past few years, elegant works on the vicinal difunctionalization of alkenyl moiety via intramolecular formyl, aryl, cyano, and heteroaryl migration has been developed . Very recently, the Zhu group reported a photoredox‐catalyzed radical trifluoromethylative alkynylation of unactivated alkenes via distal alkynyl migration . The Studer group has developed a difunctionalization of alkynyl‐substituted tertiary alcohol via 1,4‐alkenyl migration .…”

“…Based on the above experimental results and previous reports, a plausible mechanism for this electrochemical radical migration reaction was proposed in Scheme . First sodium sulfinate 2 is oxidized at the anode to give the oxygen‐centered radical A .…”

“…[8] Very recently,t he Zhu group reported ap hotoredox-catalyzed radicalt rifluoromethylativea lkynylation of unactivated alkenes via distal alkynyl migration. [9] The Studer group has developed ad ifunctionalization of alkynyl-substitutedt ertiary alcohol via 1,4-alkenyl migration. [10] These radical migration reactions mainly focused on the light initiation and metal catalysis, which usually need transition metal, photocatalysto radditives.…”

Copper‐Catalyzed Heteroarylsilylation of Unactivated Olefins through Distal Heteroaryl Migration

“…There are also a few examples reported with distal aryl migration . Recently, we consecutively studied the migratory aptitude of cyano,– heteroaryl,– imino, formyl, and alkynyl groups, and demonstrated their applications in difunctionalization of unactivated alkenes. For example, we have disclosed the trifluoromethylative heteroarylation of alkenes for the first time (Scheme A) .…”