Copper-catalyzed fluoroamide-directed remote benzylic C–H olefination: facile access to internal alkenes

Abstract

The general, site-selective copper-catalyzed fluoroamide-directed remote benzylic C–H olefination of N-fluoroamides with terminal alkenes for producing internal alkenes is disclosed. This protocol proceeds via a hybrid Cu–radical mechanism, which synergistically combines the favorable features of radical transformations (such as a site-selective remote C–H hydrogen atom transfer (HAT) step) with those of transition-metal catalysis (such as a selective β-hydrogen elimination step). The cooperative Cu and dinitrogen-based ligand catalytic systems are crucial, as they not only preferentially enable the coupling of terminal alkenes with remote benzylic C–H bonds through the chemoselective recognition of two remote δ-C(sp³)–H bonds respectively existing in two distinct alkyl-based chains linked to the nitrogen atom of the N-fluoroamides, but they also precisely control site selectivity for the olefination of remote benzylic C–H bonds in a δ position relative to the amidyl nitrogen atom.