The isomerization/chlorination of O,O-dialkyl N,N-dialkyl thiophosphoramidate with phosphorus oxychloride - A new method for synthesis of S-alkyl N,N-dialkyl thiophosphoramidic acid derivatives

A new convenient method for synthesis of S-alkyl N,N-dialkyl thiophosphoramidic acid derivatives is reported. The chlorination of O,O-dialkyl N,N-dialkyl thiophosphoramidates with phosphorus oxy chloride proceeds with isomerization to give S-alkyl N,N-dialkyl thiophosphoramidochloridates. which react further with various nucleophiles in the presence of base to give the title compounds. However, in the reaction of O,O-diethyl N,N-dimethyl thiophosphoramidate with phosphorus oxychloride, an unexpected exchange between chlorine atom and dimethylamino group is observed.