2-Methyl[1,3]oxazolo[4,5-b]pyridine

Synthesis

General procedure for the synthesis of 2-methyloxazolo[4,5-B]pyridine from 2-amino-3-hydroxypyridine and triethyl orthoacetate: 80 mL of triethyl orthoacetate was added to 15 g (136 mmol) of 2-amino-3-hydroxypyridine, followed by the addition of a catalytic amount of p-toluenesulfonic acid. The reaction mixture was stirred at 120 °C for 4 hours. After completion of the reaction, the reaction mixture was cooled and triethylamine was added to neutralize p-toluenesulfonic acid in the reaction system. Subsequently, the solvent was removed by distillation under reduced pressure using a rotary evaporator. The crude product was purified by silica gel column chromatography to afford 12.0 g of the target product 2-methyloxazolo[4,5-B]pyridine in 65.8% yield.

References

[1] Monatshefte fur Chemie, 2011, vol. 142, # 1, p. 87 - 91
[2] Heterocycles, 1995, vol. 41, # 3, p. 477 - 486
[3] Monatshefte fur Chemie, 2007, vol. 138, # 7, p. 663 - 667
[4] Patent: US2009/247736, 2009, A1. Location in patent: Page/Page column 13
[5] Tetrahedron Letters, 1990, vol. 31, # 8, p. 1155 - 1156