Potassium Carbonate → 2-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-pyrrole-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 6-bromo-4,4-dimethyl-1,4-dihydro-benzo[d][1,3]oxazin-2-one (0.87 g, 3.4 mmol) and tetrakis(triphenylphosphine)palladium(0) (96 mg, 0.08 mmol) in toluene (40 mL) was stirred under a flow of nitrogen for 25 min. To the solution was added sequentially 1-t-butoxycarbonylpyrrole-2-boronic acid (1.4 g, 7.0 mmol) in absolute ethanol (10 mL) and potassium carbonate (0.94 g, 7.0 mmol) in water (10 mL). The mixture was heated at 80° C. for 16 h and allowed to cool to rt. The reaction mixture was poured into aqueous saturated sodium bicarbonate solution (100 mL) and extracted with ethyl acetate (3×100 mL). The organic layers were combined, washed with water (100 mL) and brine (50 mL) and dried over magnesium sulfate. The solution was filtered, concentrated in vacuo, and the residue was purified by flash column chromatography on silica gel (30% ethyl acetate/hexane) to give the title compound as an off-white powder (0.7 g, 62%): mp 176° C. 1H NMR (CDCl3) δ 1.40 (s, 9H), 1.73 (s, 6 H), 6.17 (dd, 1H, J=1.8, 3.3 Hz), 6.22 (dd, 1H, J=3.3, 3.3 Hz), 6.77 (d, 1H, J=8.1 Hz), 7.13 (d, 1H, J=1.8 Hz), 7.23 (dd, 1H, J=1.8, 8.1 Hz), 7.33 (dd, 1H, J1.8, 3.3 Hz), 7.69 (bs, 1H). MS ((−) ESI) m/z 341 [M−H]−. Anal. Calcd for C19H22N2O4: C, 66.65; H, 6.48; N, 8.18. Found: C, 65.46; H, 6.51; N, 7.74.

Provenance & Evidence