[Br:1][C:2]1[C:11]2[O:10][C:9]([CH3:13])([CH3:12])[C:8](=O)[NH:7][C:6]=2[CH:5]=[CH:4][CH:3]=1.CSC.B.[ClH:19]>O1CCCC1>[ClH:19].[Br:1][C:2]1[C:11]2[O:10][C:9]([CH3:13])([CH3:12])[CH2:8][NH:7][C:6]=2[CH:5]=[CH:4][CH:3]=18-Bromo-2,2-dimethyl-4H-benzo[1,4]oxazin-3-one from step 2 (768.30 mg, 3.0 mmol) was dissolved in dry tetrahydrofuran (THF) and the solution was heated to reflux. 0.3 ml of 10M borane dimethyl sulfide (BH3.DMS) in THF was added drop-wise to the reaction mix, and the reaction mix was kept heated under reflux for 1 hour. A solution of 10% ethanolic HCl was then added drop-wise to the reaction mix until a white precipitate appeared, after which refluxing was continued for 10 minutes. The reaction mix was cooled, and the precipitate was removed by filtration, washed with ether, and air dried to yield 770 mg of 8-bromo-2,2-dimethyl-3,4-dihydro-2H-benzo[1,4]oxazine hydrochloride (92%) as a white solid. MS: (M+H) 280.
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