The first isolation of benzimidazoline ring substituted ketene aminals 7a–c and/or their amidine tautomers 7′ bd, which were synthesized by the reactions:(1) benzoyl substituted ketene mercaptals 3 with N-methyl-o-phenylenediamine 4, and (2) 1, 2- dimethylbenzimidazole 5 with ethyl benzoates 6, were disclosed. The tautomeric equilibrium between 7 and 7′, along with benzothiazoline and benzoxazoline ring substituted ketene ...
