4-Nitrophenol → 4-Nitrophenyl 2-ethyl-4-methoxybenzoxazole-7-carboxylate

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Reaction Steps

2-Ethyl-4-methoxybenzoxazole-7-carboxylate (1.24 g), 4-dimethylaminopyridine (catalytic), 4-nitrophenol (1.17 g), and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (1.6 g) in dichloromethane (60 ml) were stirred at room temperature for 48 h. The mixture was evaporated onto silica and chromatographed, eluting with 50% ethyl acetate in hexane, to yield 4-nitrophenyl 2-ethyl-4-methoxybenzoxazole-7-carboxylate. 4-Amino-3,5-dichloropyridine (0.57 g) was dissolved in N,N-dimethylformamide (20 ml) at room temperature under nitrogen. Sodium hydride (0.20 g, 60% dispersion) was added, and the mixture stirred for 5 h before addition of the 4-nitrophenyl ester (1.2 g) and stirred for a further 18 h. The reaction mixture was evaporated onto silica and and purified by flash chromatography eluting with 50% ethyl acetate in hexane to separate the title compound as a white solid (0.44 g).

Provenance & Evidence