The Synthesis of 4-Chloro-3-benzoyl-2-azetinone Derivatives and Their Conversion into N-Benzoyl-2,4-azetidinedione Derivatives

The treatment of ethyl α-cyanophenylacetate with benzoyl chloride in the presence of 2 equivalents of aluminum chloride in nitrobenzene afforded 4-chloro-3-benzoyl-3-phenyl- (6% yield) and 4-chloro-3-benzoyl-3-(p-benzoylphenyl)-2-azetinone (28%) at 50°C. The same treatment of ethyl α-cyanopropionate afforded 4-chloro-3-benzoyl-3-methyl-2-azetinone (37%). The hydrolytic splitting of the chlorine atoms from the first two azetinones resulted in the formation of N-benzoyl-2,4-azetidinedione derivatives (36 and 20% respectively), whereas from the last we obtained N-benzoyl-α-carboxypropionamide (18%). These azetinone derivatives, when warmed with sodium methoxide in methanol, were converted into α-benzoyl α-cyano esters. The treatment of α-benzoyl α-cyano esters with aluminum chloride also afforded the azetinone derivatives in low yields.