Studies in the synthesis of 5,6-benzoquinolines

Abstract

2-Phenyl- 5,6-benzolepidines were synthesized by the condensation of arylidene-2-naphthylamines with acetone in the presence of hydrochloric acid. The influence of various substitutents in the aromatic aldehydes on the course of the reaction was studied. It was shown that the introduction of certain substituents, e.g. a nitro or methyl group into the ortho-position of the azomethine residue caused an appreciable lowering in the yield of arylbenzolepidine. A cyclic product could not be obtained when the aldehyde residue contained two methyl groups in the ortho-position. The reaction of 2,4,6-trimethylbenzylidene-2-naphthylamine with acetone under severe conditions afforded the adduct β-mesityl-β-(2-naphthylamino)butanone.