4-Azaindole → 1H,2H,3H-pyrrolo[3,2-b]pyridine

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Reaction Steps

1.49 g of Raney nickel at 50% in water are added to a solution of 1.5 g of 4-azaindole in 45 ml of absolute ethanol, in an autoclave under argon. The mixture is hydrogenated under 100 bar of hydrogen at a temperature of 95° C. for 41 h. After a return to ambient temperature, the catalyst is filtered off through Clarcel and the filtrate is concentrated to dryness under reduced pressure. The residue is purified by chromatography on a 70 g 15-40 μm silica cartridge, elution being carried out with pure dichloromethane and then with a 99/1 v/v mixture of dichloromethanemethanol with a flow rate of 80 ml/min, and then on a 30 g 15-40 μm silica cartridge, elution being carried out with pure dichloromethane with a flow rate of 30 ml/min. 0.18 g of 4-azaindoline is thus obtained in the form of a pale yellow solid which melts at 63° C. (Kofler bench).

Provenance & Evidence