Nucleophilic Substitution Reaction of N-2-(1-Hydroxyindol-3-yl)ethylindole-3-acetamide and -1-hydroxyindole-3-acetamide

Syntheses of N-2-(1-hydroxyindol-3-yl)ethyl-1-hydroxyindole-3-acetamide (3a) and -indole-3-acetamide (4a) are reported. They undergo nucleophilic substitution reaction at the 1-position upon reaction with indole in 85% formic acid to give new type compounds, N-2-[1-(indol-3-yl)indol-3-yl]ethylindole-3-acetamide (13), N-2-(indol-3-yl)ethyl- (14), and N-2-[1-(indol-3-yl)indol-3-yl]ethyl-1-(indol-3-yl)indole-3-acetamide (15).