First, the radical trapping experiment using 3.0 equivalents of 2,2,6,6-tetramethyl-1piperinedinyloxy (TEMPO) or butylated hydroxytoluene (BHT) resulted in the inhibition of the radical addition (Figure ). The radical clock experiment was carried out using (1-(2-phenylcyclopropyl) vinyl) benzene 1 as substrate and we successfully obtained the ringopened product 19 with a 65% isolated yield under the standard conditions E (Figure