X=Y-ZH compounds as potential 1,3-Dipoles. Part 281,2 the iminium ion route to azomethine ylides. background and reaction of amines with bifunctional ketones.
The reaction of isatin, ninhydrin and acenaphthenequinone with primary and secondaryamines gives rise to stereospecific formation of intermediate azomethine ylides which can be trapped by cycloaddition to methyl acrylate or N-methylmaleimide. The regiochemistry of the cycloadditions to methyl acrylate is controlled by both frontier orbital and steric interactions with the latter dominating in the