Studies in the formation of heterocyclic rings containing nitrogen. Part XX. Products of pyrolysis of 1, 3-dibenzyl-2-substituted-5-chloro benzimidazolines

1, 3-dibenzyl-2-substituted-5-chloro benzimidazolines have been prepared from N, N2-dibenzyl-4-chloro-o-phenylenediamine and various aldehydes. Pyrolysis of these benzimidazolines yielded 1-benzyl-2-substituted-5-chloro-benzimidazoles, by preferential elimination of benzyl group from the N, meta to chloro group. Structure of the pyrolytic products has been confirmed by comparison with authentic 5-chloro and 6-chloro isomers