ETHYL IMIDAZO[1,5-A]PYRIDINE-3-CARBOXYLATE

Synthesis

General procedure for the synthesis of ethyl imidazo[1,5-a]pyridine-3-carboxylate from ethyl 2-oxo-2-((pyridin-2-ylmethyl)amino)acetate: ethyl [(pyridin-2-ylmethyl)carbamoyl]formate (1.00 g, 4.80 mmol, 1.00 equiv) and phosphorus pentoxide (3.41 g, 24.02 mmol, 5.00 equiv) were dissolved in phosphoryl chloride (30 mL). ) were dissolved in phosphoryl chloride (30 mL) and the reaction was stirred at 110°C for 5 hours. After completion of the reaction, the mixture was concentrated under reduced pressure. The residue was purified by silica gel column chromatography with ethyl acetate/petroleum ether (1:1, v/v) as eluent. 635 mg (70% yield) of the target product, ethyl imidazo[1,5-a]pyridine-3-carboxylate, was finally obtained as a yellow solid.LC-MS (ESI, m/z): 191 [M + H]+.

References

[1] Patent: WO2015/25025, 2015, A1. Location in patent: Page/Page column 411; 412
[2] Patent: WO2008/85302, 2008, A1. Location in patent: Page/Page column 96
[3] Organic Letters, 2013, vol. 15, # 9, p. 2290 - 2293
[4] Synthesis (Germany), 2016, vol. 48, # 23, p. 4269 - 4277