Phosphorus oxychloride → Imidazo(1,5-a)pyridine

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Reaction Steps

To 13.6 g. of 2-formamidomethylpyridine in a round-bottom flask is added 25 ml. of phosphorous oxychloride. Following the exothermic reaction, the reaction mixture is cooled to room temperature, and quenched on crushed ice. The aqueou mixture is treated with sufficient 20% aqueous sodium hydroxide solution to provide a pH of 9-10, and the liberated product extracted into chloroform (3 × 300 ml.). The extracts are combined, dried over sodium sulfate and concentrated to give imidazo[1,5-a]pyridine as a light brown oil, 14.0 g. b. The procedure of Preparation AII-a is repeated starting with the appropriate reagents to provide the following intermediates:

Provenance & Evidence