Copper-Catalyzed Linear Remote Double Functionalization of Enynes

This is the authors' abstract. We don't add key points for this paper.

Abstract 1,7-Enynes usually undergo cyclizative double functionalization. Herein, we report a conceptual radical-based noncyclizative linear remote double functionalization of enynes. Different from classic facile cyclizations involving two unsaturated carbon–carbon bonds, the alkyl radical generated in situ undergoes hydrogen atom transfer with the propargylic C–H bond to generate a propargylic radical via a highly chemo- and regioselective radical addition with the C=C bond over the C≡C bond, which would be in equilibrium with an allenyl radical. Subsequent exclusive trapping with trimethylsilyl cyanide (TMSCN) afforded a variety of CF3-containing allenenitriles tolerating many functional groups with great synthetic potentials in the presence of a copper catalyst. In addition to 1,5-hydrogen atom transfer, 1,6-hydrogen atom transfer and even 1,7-hydrogen atom transfer have also been observed. This protocol opens a dimension for the reactions of compounds with multiple unsaturated units.