Abstract Treatment of ethyl (E)-5, 5-bis [(benzyloxy) methyl]-8-(N, N-diethylcarbamoyl)-2- octen-7-ynoate with an iron reagent generated from FeCl 2 and tBuMgCl in a ratio of 1: 4 (abbreviated as FeCl 2/4 tBuMgCl) afforded ethyl [4, 4-bis [(benzyloxy) methyl]-2-[(E)-(N, N- diethylcarbamoyl) methylene] cyclopent-1-yl] acetate in good yield. Deuteriolysis of an identical reaction mixture afforded the bis-deuterated product ethyl [4, 4-bis [(benzyloxy) ...