Synthesis and unexpected reactions of 2-Hydroxy-3-pyridinylacetic hydrazides. Formation of 2H-Pyrrolo[2,3-b]pyridin-2-ones

Treatment of 2-hydroxy-3-pyridinylacetic hydrazides under mild mesylation conditions provided 2H-pyrrolo[2,3-b]pyridin-2-ones as unexpected products. This rearrangement is believed to result from an intramolecular attack of the hydrazide on a reactive pyridinium species formed under the reaction conditions.