[CH2:1]([N:5]1[C:10]2[CH:11]=[C:12]([C:16]([O:18][CH3:19])=[O:17])[CH:13]=[C:14]([I:15])[C:9]=2[O:8][CH2:7][C:6]1=O)[CH2:2][CH2:3][CH3:4].B1C2CCCC1CCC2.C(CN)O>O1CCCC1>[CH2:1]([N:5]1[C:10]2[CH:11]=[C:12]([C:16]([O:18][CH3:19])=[O:17])[CH:13]=[C:14]([I:15])[C:9]=2[O:8][CH2:7][CH2:6]1)[CH2:2][CH2:3][CH3:4]A solution of Methyl 4-butyl-8-iodo-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylate (680 mg) and 9-BBN (900 mg) in tetrahydrofuran (30 mL) was heated at reflux for 1.5 h. The mixture was cooled to room temperature, ethanolamine (0.22 mL) was added, and the resulting solution was concentrated under reduced pressure. The residue was washed with hexanes, filtered, and the filtrate was concentrated under reduced pressure. Purification by flash column chromatography (silica, 10% ethyl acetate/hexanes) afforded 600 mg of the title compound: 1H NMR (300 MHz, CDCl3) δ 7.75, 7.28, 4.34, 3.86, 3.36, 3.28, 1.58, 1.40, 0.96.
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