A mixture of 6-(3-bromo-phenyl)-4,4-dimethyl-1,4-dihydro-benzo[d][1,3]oxazin-2-one (0.25 g, 0.75 mmol), tri-n-butyl-thiazol-2-yl tin (0.5 g, 1.3 mmol) in DMF (5 mL) was degassed to remove oxygen and then heated under nitrogen at 90° C. for 3 hours. The reaction mixture was cooled to rt and treated with ice-water (70 mL). Ethyl acetate (100 mL) was added and organic layer was separated, washed with brine, and dried (MgSO4). After removal of solvent, the residue was purified by a silica gel column (hexane:ethyl acetate/1:1) to give the title compound as a white solid (60 mg, 23%): mp 223-224° C.; 1H-NMR (DMSO-d6) δ10.4 (s, 1H), 9.13 (s, 1H), 8.45 (s, 1H), 7.94 (bs, 1H), 7.67-7.61 (m, 4H), 7.53 (t, 1H, J=7.68 Hz), 7.00 (d, 1H, J=8.81 Hz), 1.7 (s, 6H); MS (APCI) m/z 337([M+H]+, 100%), Anal. Calc. For C19H16N2O2S.0.25 H2O: C, 66.94; H, 4.88; N, 8.22. Found: C, 66.57; H, 4.65; N, 7.92.
