A concise synthesis of 6H-Indolo[2,3-b]quinolines: Formal synthesis of Neocryptolepine

Abstract

A new two-step approach for the synthesis of 6H-indolo[2,3-b]quinolines is described using indole C3 alkylation and a one-pot reduction-cyclization-aromatization sequence. The synthesis of the parent 6H-indolo[2,3-b] quinoline system constitutes a formal synthesis of the alkaloid neocryptolepine (cryptotackieine).