[F:1][C:2]1[C:7]2[O:8][CH2:9][CH2:10][NH:11][C:6]=2[CH:5]=[C:4]([B:12]2[O:16][C:15]([CH3:18])([CH3:17])[C:14]([CH3:20])([CH3:19])[O:13]2)[CH:3]=1.C([O-])([O-])=O.[K+].[K+].N#N.[CH2:29](Br)[CH:30]=[CH2:31]>CN(C=O)C.O>[CH2:31]([N:11]1[CH2:10][CH2:9][O:8][C:7]2[C:2]([F:1])=[CH:3][C:4]([B:12]3[O:16][C:15]([CH3:18])([CH3:17])[C:14]([CH3:20])([CH3:19])[O:13]3)=[CH:5][C:6]1=2)[CH:30]=[CH2:29]
A solution of 8-fluoro-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydro-2H-benzo[b][1,4]oxazine (0.507 g, 1.613 mmol, Ref. WO20100130034) and K2CO3 (0.512 g, 3.70 mmol) in dry DMF (5 mL) was sparged with N2 for 5 min, then treated with allyl bromide (0.8 mL, 9.17 mmol). The reaction tube was sealed and then heated (70° C.) for 22 h. The reaction was cooled then diluted with water (50 mL) and extracted into EtOAc (50 mL). The organic layer was then washed with water, brine, dried (Na2SO4), filtered, and concentrated. The residue was purified by biotage column chromatography (12 g SiO2, 0% (3 CV); 0-40% (15 CV), 40% (2 CV), EtOAc in hexanes) to afford the desired product (0.396 g, 1.241 mmol, 77% yield) as a clear viscous oil. 1H NMR (500 MHz, CDCl3) δ 6.96-7.01 (m, 2H), 5.84-5.95 (m, 1H), 5.21-5.32 (m, 2H), 4.32-4.38 (m, 2H), 3.94 (d, J=5.8 Hz, 2H), 3.30-3.37 (m, 2H), 1.32 (s, 12H). LCMS (M+H)=320.3.
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