A General Synthesis of 4-Substituted 6-(2-Imidazolinylamino)-5,8-dimethylquinolines.

A general synthesis of 4-substituted 6-(2-imidazolinylamino)-5,8-dimethylquinolines 1 has been developed. All new compounds were synthesized from a common intermediate, 5,8-dimethyl-6-nitro-4-quinolone 3, the structure of which was confirmed by X-ray crystallography. This methodology involved the conversion of 3 into either a 4-chloro- or 4-bromoquinoline followed by the introduction of various 4-substituents late in the synthetic sequence. Substituents introduced in this way include alkyl (18a), alkoxy (12a, 12b), halo (9, 12c, 16), cyano (18b), thioalkyl (12d), acetamido (14), carboxamido (19), and hydroxy (10). This work illustrates the utility of 4-haloquinoline intermediates in the general synthesis of 4-substituted quinolines.