Synthesis
To a 50 mL single-necked round-bottomed flask equipped with a magnetic stirrer was added 2-amino-4-nitrophenol (5.0 mmol, 1.0 eq.) and triethyl orthoformate (60.0 mmol, 12.0 eq.). The reaction mixture was slowly heated to 150 °C and the reaction was stirred at this temperature for 6 hours. Upon completion of the reaction, the mixture was cooled to room temperature, followed by distillation under reduced pressure to remove the excess triethyl orthoformate and the resulting ethanol by-product. The crude product was purified by silica gel column chromatography to give the final target compound 5-nitrobenzoxazole (see Table S-2).
References
[1] Angewandte Chemie - International Edition, 2011, vol. 50, # 48, p. 11511 - 11515
[2] Journal of the Chinese Chemical Society, 2015, vol. 62, # 5, p. 412 - 419
[3] Tetrahedron, 2013, vol. 69, # 32, p. 6627 - 6633
[4] Comptes Rendus Chimie, 2013, vol. 16, # 11, p. 1029 - 1034
[5] Angewandte Chemie - International Edition, 2009, vol. 48, # 48, p. 9127 - 9130
