A Convenient Method for the Preparation of 5-, 6- and 7-Azaindoles and Their Derivatives

The directed ortho lithiation of 2-tert-butoxycarbonylamino-3-methylpyridine (6a) has provided a convenient method for the preparation of 1H-pyrrolo[2,3-b]pyridine (4a, 7-azaindole). This procedure has been used to prepare a range of 3-substituted 2-tert-butoxycarbonylaminopyridines 6, 2- and 3-substituted and 2,3-disubstituted 1H-pyrrolo[2,3-b]pyridines 4 and shown to be of value in the preparation of 1H-pyrrolo[3,2-c]pyridine (15, 5-azaindole) and 1H-pyrrolo[2,3-c]pyridine (18, 6-azaindole) and derivatives.