Improved preparation and structural investigation of 4-aryl-4-oxo-2-hydroxy-2-butenoic acids and methyl esters

A simple and efficient oxalylation of aryl methyl ketones was accomplished with dimethyl oxalate in the presence of sodium methoxide. The unpreviously reported sodium ketoenolate esters were isolated and gently hydrolyzed into the ketoenol esters in good yields. Alternatively the sodium ketoenolate esters hydrolysis could also be conducted to directly afford the ketoenol acids, which represent one of the most promising class of HIV-1 integrase inhibitors. Advantages over previously reported procedures were better yields and simplicity of the purification protocol.