Synthesis of 1-substituted indoles by the vapour phase reaction of N-substituted anilines with glycols and epoxides over a solid catalyst and a vapour phase dealkylation of 1-alkylindole

Abstract

1-Substituted indoles 4b–h, 5c, e were synthesized in good yields by the vapour phase reaction of N-substituted anilines 1b–e with glycols 2a–c and epoxides 3a, b at 250–400 °C over a solid catalyst, Neobead P (Al₂O₃:SiO₂:Na₂O = 88:9:3), at atmospheric pressure. 1-Alkylindoles 4b, d, g were converted into indole (4a) in good yields by a vapour phase reaction with steam and hydrogen gas over ZnO (10%) supported on Neobead C (Al₂O₃) at 500–575 °C. These reaction pathways are discussed.