In a preceding paper2 we described the intramolecular cyclizations of N-(phenylpropargy1)- cis-cinnamamide in refluxing acetic anhydride to form (Z)-l-acetyl-4-(1, 2-di-phenylvinyl)-3- pyrrolin-2-one (1; resulting from [2+ 21 cycloaddition-cycloreversion), as well as [4+ 21 cycloaddition products. The bromo derivative 2 and the dideuterio derivative 3 were obtained analogously. Structural elucidations of 1-3 were reported previ~ usly.~*~ The ...