Synthesis of β- and γ-Carbolines and Their N-Oxides from 2(or 3)-Ethynylindole-3(or 2)-carbaldehydes

Abstract

Isoquinoline-type carbolines i.e. β-, and γ-carbolines and their N-oxides were synthesized from 2(or 3)-ethynylindole-3(or 2)-carbaldehydes, which were synthesized by electrophilic substitution with dichloromethyl methyl ether in the presence of titanium tetrachloride, or by lithiation with tert-butyllithium, followed by formylation with methyl formate.