Interaction of 2-methyl-2,5-dioxo-1,2-oxaphospholane with trimethylsilyl cyanide

The reaction of 2-methyl-2,5-dioxo-1,2-oxaphospholane (1) with trimethylsilyl cyanide was found to give, depending on conditions, three organophosphorus compounds: trimethylsilyl methyl(2-cyanocarbonylethyl)phosphinate (2), trimethylsilyl methyl(3-trimethylsiloxy-3,3-dicyanopropyl)phosphinate (3) and trimethylsilyl methyl(3-trimethyl-siloxy-3-cyano-2-propenyl)phosphinate (4), On hydrolysis of3 under mild conditions, methyl(3-hydroxy-3,3 dicarboxypropyl)phosphinic acid (7) was obtained. The latter is readily decarboxylated on heating to give methyl(3-hydroxy-3-carboxy-propyl)phosphinic acid (8). The interaction of2 and4 with water or alcohols gives, correspondingly, methyl[2-carboxy(alkoxycarbonyl) ethyl]phosphinic acids (11–13). Methyl(2-oxamoyiethyl)phosphinic acid (14) was prepared by successive treatment of propenylphosphinate4 with HCl gas and water.