Structure and properties of the products of the reactions of trialkylphosphites and dialkylphosphorous acids with ethylideneacetylacetone and ethylideneacetoacetic ester

1. Trialkylphosphites react with ethylideneacetylacetone and ethylideneacetoacetic ester under mild conditions (20-40°, dry nitrogen atmosphere) to form 2,2,2-trialkoxy-3,5-dimethyl-4-acetyl-1-oxa-2-phosphacyclopent-4-enes and 2,2,2-trialkoxy-3,5-dimethyl-4-carboethoxy-1-oxa-2-phosphacyclopent-4-enes, respectively. 2. The reaction of the phosphoranes with alcohol, acetic anhydride, and water results in cleavage of the phosphorane ring at the P-O bond. 3. Hydrolysis of the phosphoranes yields esters of l-methyl-2,2-diacetyl- and 1-methyl-2-acetyl-2-carboethoxyethylphosphonic acids. The keto-enol tautomerism of these compounds was studied by ultra-violet spsctroscopy. 4. Distillation of the phosphorane hydrolysis products resulted in the splitting out of alcohol and the formation of 2-oxo-2-alkoxy-3,5-dimethyl-4-acetyl-1-oxa-2-phosphacyclopent-4-enes and 2-oxo-2-alkoxy-3, 5-dimethyl-4-carboethoxy-l-oxa-2-phosphacyclopent-4-enes, respectively. These same esters were also obtained from the reaction of ethylideneacetylacetone and ethylideneacetoacetic ester with dialkylphosphorous acids. 5. The structures of all compounds synthesized were confirmed by infrared spectra. © 1968 Consultants Bureau