Ethyl orthoformate → 3-(1-diethoxymethyl-4,4-dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-5-fluoro-benzonitrile

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Reaction Conditions

Reaction Steps

A mixture of 3-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6yl)-5-fluoro-benzonitrile (0.25 g, 0.84 mmol) and triethylorthoformate (50 mL) was heated at 160° C. for 12 hours. The excess triethylorthoformate was removed in vacuo and purification via chromatography (silica gel, 20% ethyl acetate/hexane) gave 3-(1-diethoxymethyl-4,4-dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-5-fluoro-benzonitrile (0.116 g, 33%) as a white solid: mp 123-124° C.; 1H-NMR (DMSO-d6) δ 7.97 (d, 1H, J=8.68 Hz), 7.66 (bs, 1H), 7.53-7.44 (m, 2H), 7.35-7.32 (m, 2H), 6.65 (s, 1H), 3.88-3.78 (m, 2H), 3.73-3.61 (m, 2H), 1.77 (s, 6H), 1.27 (t, 6H), J=7.05 Hz); MS (ESI) m/z 295 ([M−H]−, 100%, lower MW ion consistent with loss of diethyl acetal); Anal. Calc. For C21H23FN2O4: C, 66.32; H, 5.82; N, 7.03. Found: C, 65.89; H, 5.92; N, 6.66.

Provenance & Evidence