Conversion of 2-chloroallylamines into heterocyclic compounds. Part I. 2-Methylindoles,1,5,6,7-tetrahdyro-3-methylindol-4-ones, and related heterocycles

Abstract

Heating several N-(2-chloroallyl)anilines with polyphosphoric acid at 100 °C or with boron trifluoride–methanol at 150 °C gave 2-methylindoles. 2-Methyloxazolo[3,2-a]quinolin-5-one, imidazo[1,2-a]pyridine, and 2-methyl-pyrrolo[3,2-c]quinolines were similarly obtained from N-(2-chloroallyl)-4-hydroxyquinoline-2-one, 2-(2-chloroallylamino)pyridine and 4-[N-(2-chloroallyl)-ethylamino]- and -anilino]-quinolines, respectively. 1-Ethyl and 1-aryl-1,5,6,7-tetrahydro-3-methyl-6,6-dimethylindol-4-ones were obtained from the corresponding dimedone enamines on treatment with polyphosphoric acid. 3-Acetonyl-,4,6-trimethylaniline was obtained in excellent yield from N-(2-chloroallyl)-2,4,6-trimethylaniline.