Synthesis
The general procedure for the synthesis of 2-methyl-6-hydroxybenzoxazole from the compound (CAS:111364-29-5) was as follows: (1Z)-1-(2,4-dihydroxyphenyl)ethanone oxime (9.7 g, 57.7 mmol) was dissolved in a mixed solvent of acetonitrile (65 mL) and dimethylacetamide (11 mL) and cooled to 5 °C. Phosphorus trichloride (5.6 mL, 60.3 mmol) was slowly added dropwise at a temperature not exceeding 10 °C. After the dropwise addition, the reaction mixture was stirred at room temperature for 1 h. The reaction solution gradually formed a yellow slurry. The reaction mixture was carefully poured into a pre-prepared mixture of sodium bicarbonate and ice for neutralization. The resulting precipitate was collected by filtration and dried to give 6.3 g of 2-methyl-6-hydroxybenzoxazole in 73% yield.
References
[1] Bioorganic and Medicinal Chemistry Letters, 2003, vol. 13, # 24, p. 4313 - 4316
[2] Patent: WO2004/5295, 2004, A1. Location in patent: Page 99
[3] Patent: WO2005/61499, 2005, A1. Location in patent: Page/Page column 41
[4] Patent: WO2005/37814, 2005, A1. Location in patent: Page/Page column 35
