Photoinduced Copper-Catalyzed Monofluoroalkylation of Terminal Alkynes to Propargylic Fluorides

Abstract

A photoinduced copper-catalyzed strategy for the monofluoroalkylation of alkynes with readily available monofluoroalkyl triflates was developed. It provides a new protocol to access valuable propargyl fluoride compounds via C−C bond formation by avoiding the use of highly toxic fluorination reagents. This reaction proceeded under mild conditions to afford propargyl monofluorides in moderate to high yields. Preliminary mechanistic studies reveal that a ligand-matched alkynyl copper complex might be the key photoactive substance.

Visible-Light-Induced Excited-State Copper Catalysis: Recent Advances and Perspectives

“…This radical subsequently combines with the Cu(II) complex to form the desired coupling product 79 while regenerating the Cu(I) species. Alkyl radical precursors, such as alkyl thianthrenium salts (Scheme a, 80 ) and 1-fluoro-3-arylpropyl triflates (Scheme b, 82 ) have been reported for coupling with terminal alkynes by excited copper catalysis, thereby forming a variety of C(sp)–C(sp) bonds. The Zhang group recently reported the use of 1-aroyl-pyrrolidine 84 as an aryl radical precursor, which engages in an intramolecular 1,5-hydrogen atom transfer (HAT) process to generate an alkyl radical .…”