A diastereoselective synthesis of cyclopentanones via photocatalytic reductive alkyltrifluoromethylation of ynones

Abstract

Traditional alkyne carbotrifluoromethylation protocols lead to the production of trifluoromethylated alkenes, while new reaction modes remain to be explored. Herein, a visible light induced reductive alkyltrifluoromethylation of ynones with the Langlois reagent is developed, providing a regio- and diastereoselective access to highly functionalized trifluoromethylated cyclopentanones at room temperature. Mechanistic studies suggest a radical pathway involving the regioselective trifluoromethylation of C–C triple bonds, 1,5-HAT, 5-endo-trig closure, single electron transfer reduction, and protonation.