Nucleophilic substitution reaction at the 1-position of 1-hydroxytryptamine and -tryptophan derivatives

A novel nucleophilic substitution reaction at the 1-position of indole nucleus was discovered by reacting 1-hydroxytryptamine and -tryptophan derivatives with indoles in 85% formic acid yielding 1-(indol-3-yl)indoles. Their structures were determined by X-Ray crystallographic analysis and chemical correlations. An SN2 mechanism on the indole nitrogen (1-position) is proposed.