Reaction of 1-phenyl-3-methyl-4-(p-dimethylamidoanil)-5-pyrazolone and 5-benzylidene-3-phenyl-2,4-thiazolidinedione with dimethylphosphorous acid and tri(dimethylamino)phosphine

1. The reaction of dimethylphosphorous acid with l-phenyl-3-methyl-4-(p-dimethylamidoanil)-5-pyrazolone (I) gives the dimethyl ester of (1-phenyl-3-methyl-5-hydroxy-4-pyrazolyl)-p-dimethylamidoanilphosphonic acid (III), while reaction with 5-benzylidene-3-phenyl-2,4-thiazolidinedione (II) gives the dimethyl ester of (3-phenyl-2,4-thiazolidinedion-5-yl)benzylphosphonic acid (V). 2. The corresponding salt is formed when thiazolidinedione (II) is reacted with dimethylphosphorous acid in the presence of diethylamine or triethylamine. 3. Pyrazolone (I) and thiazolidinedione (II) form the 1:1 bipolar adducts with tri(dimethylamino)phosphine. © 1976 Plenum Publishing Corporation