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 trimeth ylsilyl cyanide was found to give, depending on conditions, three orga nophosphorus compounds: trimethylsilyl methyl(2-cyanocarbonylethyl)pho sphinate (2), trimethylsilyl yl(3-trimethylsiloxy-3,3-dicyanopropyl)ph osphinate (3) and trimethylsilyl methyl(3-trimethyl-siloxy-3-cyano-2-p ropenyl) phosphinate (4). On hydrolysis of 3 under mild conditions, me thyl(3-hydroxy-3,3-dicarboxypropyl)phosphinic acid (7) was obtained. T he latter is readily decarboxylated on heating to give methyl(3-hydrox y-3-carboxy-propyl)phosphinic acid (8). The interaction of 2 and 4 wit h water or alcohols gives, correspondingly, methyl[2-carboxy(alkoxycar bonyl)-ethyl]phosphinic acids (11-13). Methyl(2-oxamoylethyl)phosphini c acid (14) was prepared by successive treatment of propenylphosphinat e 4 with HCl gas and water.