Synthesis of 4-oxo-3a,4,5,6-tetrahydroimidazo[1,5-b]isoxazole-3-carboxylic acid esters

Abstract

3-Imidazoline 3-oxides react regioselectively with 3-phenylpropanoic acid alkyl esters to give the corresponding 2-phenyl-3a,4,5,6-tetrahydroimidazol 1,5-b]isoxazole-3-carboxylic acid alkyl esters. This adducts convert to imidazole and the corresponding. alkyl 3-oxo-3-phenylpropanoic acid esters when treated with alkoxides or heated under vacuum. Attempts to oxidise the carbon-carbon double bond using KMnO4-FeSO4 led to the formation of heretofore unknown 4-oxo-3a,4,5,6-tetrahydroimidazo[1,5-b]isoxazoles.