The synthesis, reactions, and spectra of 1-acetoxy-, 1-hydroxy-, and 1-methoxy-indoles

Abstract

Reduction of 2-nitrophenylacetaldehyde gave the unstable 1-hydroxyindole, trapped as 1-acetoxyindole. Concurrent alkaline hydrolysis with methyl iodide present yielded 1-methoxyindole which was substituted by electrophiles at position 3. The 3-carbaldehyde, from a Vilsmeier reaction, was converted into 1-methoxy-NN-dimethyl-tryptamine. 1,5-Dimethoxyindole underwent the Mannich reaction forming the 3-dimethylaminomethyl derivative. 1-Acetoxyindole with dimethylformamide and phosphoryl chloride yielded 2-chloroindole-3-carbaldehyde and 1-hydroxyindole-3-carbaldehyde, while (1-hydroxyindol-3-yl)glyoxylic acid with hydroxylamine gave 3-cyano-1-hydroxyindole or indole-3-nitrile oxide. The u.v.,i.r.,n.m.r., and mass spectra of the 1-hydroxyindole derivatives are discussed.