The cycloaddition of various types of cu,@-unsaturated imines with diphenyl-and dichloroketenes yields both (2+ 2) and (4+ 2) cycloaddition products, ie,@-lactams and 6- lactams7 respectively. The cycloaddition products are dependent upon substitution in the imine and the ketene. The 6-lactams derived from dichloroketene are easily dehydrochlorinated to the corresponding 2-pyridones. All of the results are consistent with ...
