Synthesis
General procedure for the synthesis of 2-methyl-6-amino benzoxazole from 2-methyl-6-nitrobenzoxazole: To a methanolic (60 mL) suspension of 6-nitro-2-methylbenzoxazole (4.00 g, 22.4 mmol) heated to 70 °C, a water (40 mL) solution of ammonium chloride (12.1 g, 0.227 mol) and iron powder (4.52 g, 80.1 mmol). The reaction mixture was stirred at 70 °C for 2 h. After completion of the reaction, it was filtered through diatomaceous earth and washed with methanol. The filtrate was concentrated and the residue was partitioned between water and ethyl acetate. The organic layers were combined and the solvent was removed under reduced pressure to afford the target product 2-methyl-6-aminobenzoxazole in a yield of 2.83 g (85% yield). The product was analyzed by high performance liquid chromatography (HPLC) with 100% purity (System A); low resolution electrospray ionization mass spectrometry (LRESIMS, ESI+) showed m/z = 149 ([M + H]+).
References
[1] Patent: WO2009/150144, 2009, A1. Location in patent: Page/Page column 137
[2] Organic and Biomolecular Chemistry, 2014, vol. 12, # 28, p. 5082 - 5088
[3] Journal of the Chemical Society, 1928, p. 121
[4] Journal of the Chemical Society, 1930, p. 2685,2687
[5] DRP/DRBP Org.Chem.,
