Process for preparing 5-aza-indole and compound obtained by this process

Abstract From the Canadian patent

The invention relates to a novel process of preparing 5-aza-indole : whereby, in the presence or absence of a solvent 3-methyl-4-nitro-pyridine-, 1-oxide is condensed with a compound of the general formula : in which R represents a dimethylamino, diethylamino dipropylamino, dibutyl-, amino, morpholino piperidino or pyrrolidino group and R1 and R2 the same, or different, each represent a methoxy ethoxy or propoxy group or a group, R as defined above to obtain the corresponding enamine which is then submitted to reduction cyclisation with hydrogen in the presence of a catalyst to provide the required 5-aza-indole.