Structure and properties of reaction products of benzylidenebenzoylacetone with trimethyl phosphite and dimethylphosphorous acid

1. Trimethyl phosphite reacts with benzylidenebenzoylacetone to give the 1:1 adduct, which contains a pentacoordinated phosphorus atom. 2. In solution the obtained 1,2-oxaphospholene represents a mixture of two isomers, while in the solid state it has the structure of 2,2,2-trimethoxy-3,5-diphenyl-4-acetyl-1,2-oxa-4-phospholene. 3. The spectral and some of the chemical properties of the obtained phosphorane were studied. 4. Dimethylphosphorous acid adds to benzylidenebenzoylacetone to give the dimethyl ester of 1-phenyl-2-acetyl-2-benzoylethylphosphonic acid. Its keto-enol tautomerism was studied employing UV spectroscopy. © 1975 Plenum Publishing Corporation