Synthetic Routes to Quinoline Derivatives: Novel Syntheses of 3-Butyryl-8-methoxy-4-[(2-methylphenyl)amino]quinoline and 3-Butyryl-8-(2-hydroxyethoxy)-4-[(2-methylphenyl)amino]quinoline

Abstract

The 3,4,8-trisubstituted quinoline derivatives 2-butyryl-8-methoxy-4-[(2-methylphenyl)amino]quinoline and 3-butyryl-8-(2-hydroxyethoxy)-4-[(2-methylphenyl)amino]quinoline were prepared using five novel synthetic strategies, each involving a different disconnection as a basis for the key step. One such strategy led to the development of highly efficient processes for the large-scale preparations of both compounds and featured a facile cyclisation of an [(arylamino)methylene]malonate and an unusual Reformatsky reaction of a quinoline-3-carboxylate with tert-butyl 2-bromobutyrate in the presence of zinc.