Reductive desulfurization of 4 was accomplished with aluminum amalgamg to yield diethyl acetamidovinylmalonate (5, Ha, Hb, H,= IH). Complete retention of configuration was observed when the same procedure was applied to (2)-and (E)-[3, 4-2H2]-4, affording (E)-[3, 4-and H,= 2H, Hb= lH), respectively. The isomers of 5 monodeuterated at C-4,(E)-[4-2H1]-5 and (2)-[4-2HJ-5, were obtained by corresponding reduction of (E)-and (2)-4, respectively, ...