Reaction of trimethyl phosphite and dimethylphosphorous acid with 1-phenyl-3-methyl-4-benzylidene-5-pyrazolone

Abstract

1. Trimethyl phosphite adds to l-phenyl-3-methyl-4-benzylidene-5-pyrazolone in two ways: To the\( - CH = C - C = N and - CH = C - \begin{array}{*{20}c} C \\ {||} \\ o \\ \end{array} -\) conjugated systems to form dimethyl (l-phenyl-2,3-dimethyl-5-pyrazolon-4-yl)benzylphosphinate and dimethyl (1-phenyl-3-methyl-5-methoxy-4-pyrazolyl)benzylphosphinate. 2. The structures of the products are confirmed by chemical and spectroscopic data.