1,1,2-Trifunctionalization of Terminal Alkynes by Radical Addition-Translocation-Cyclization-Trapping for the Construction of Highly Substituted Cyclopentanes.

Abstract

Radical 1,1,2-trifunctionalization of terminal alkynes by an addition-translocation-cyclization-trapping sequence using readily available alkynyl triflones as trifluoromethyl radical precursors and trapping reagents is reported. Cascades occur by addition of the trifluoromethyl radical to a terminal alkyne, 1,5-hydrogen atom transfer, 5-exo-cyclization, and subsequent alkynylation to provide (1-trifluoromethyl)propargyl cyclopentanes. Reactions proceed with commercial dibenzoyl peroxide or α,α'-azobisisobutyronitrile as the initiator at elevated temperature and provide the highly substituted cyclopentanes in good yields.