Ethyl orthoformate → 7-Methoxybenzo[d]oxazole

Participants

Reaction Steps

A mixture of 2-nitro-6-methoxyphenol (2.62 g, 15.5 mmol) (EP 333176) and 10, Palladium on carbon (130 mg) in ethanol (50.0 ml) was stirred under an atmosphere of H2 for 75 min. The mixture was filtered through Celite® then immediately treated with p-toluenesulphonic acid (32.0 mg) and triethylorthoformate (6.45 ml, 38.8 mmol) then heated under reflux under an atmosphere of N2. After 20 h p-toluenesulphonic acid (30.0 mg) and triethylorthoformate (6.45 ml, 38.8 mmol) were added. After a total of 44 h heating, the reaction was allowed to cool and reduced in vacuo. The resulting residue was purified by flash chromatography (25:75 ethyl acetate/hexane) to give 1.97 g (85%) of the title compound as a yellow solid: m.p. 28-31° C.; IR (film) 1629, 1497, 1434, 1285, 1097; 1H NMR (CDCl3) δ 8.09 (1H, s), 7.40 (1H, d, J=8.0), 7.28 (1H, t, J=8.0), 6.89 (1H, d, J=8.0), 4.02 (3H, s); 13C NMR (CDCl3) δ 152.84, 145.82, 142.50, 139.99, 125.75, 113.42, 108.80, 56.97. Anal. Calcd. for C8H7N1O2.0.1H2O: C, 63.65; H, 4.81; N, 9.29. Found: C, 63.43, H, 4.88; N, 9.05. M.S. (+FAB); 150 (M++1).

Provenance & Evidence