Synthesis of pyrrolo[2,3- d ]pyridazines and pyrrolo[2,3- c ]pyridines (6-azaindoles). Experimental and theoretical study.

A new synthetic route towards 6-azaindoles (pyrrolo[2,3- c ]pyridines) and pyrrolo[2,3- d ]pyridazines starting from 4-aroyl pyrroles is described. This overall protocol involves: (i) the Vilsmeier-Haack reaction to obtain pyrrolo-2,3-dicarbonyles and (ii) condensation with hydrazines or glycine methyl ester. The reaction mechanism between pyrrolo-2,3-dicarbonyl with phenyl hydrazine and glycine methyl ester has been modelled using DFT calculations to prove the formation of one from two possible isomers of condensation.