A new synthesis of indoles particularly suitable for the synthesis of tryptamines and tryptamine itself

Abstract

2-Amino-1-o-bromophenylethanols (4) give indoles (5) when heated to 140–170 °C in a solution of ammonia in methanol. The reaction is suitable for the synthesis of a wide variety of 1-, 3-, 5-, and 6-substituted indoles and, because the starting materials are easy to make, it is particularly suitable for the synthesis of N(b)-di-substituted tryptamines (15). Tryptamine itself can be made in 31% yield (based on o-bromobenzoic acid) by using benzyl groups as the N(b)-substituents, and removing them by hydrogenolysis.