[Br:1][C:2]1[CH:3]=[C:4]2[C:9](=[C:10]([CH2:12][N:13]([CH:16]3[CH2:18][CH2:17]3)[CH:14]=O)[CH:11]=1)[O:8][C:7]([CH3:20])([CH3:19])[CH2:6][C:5]2([CH3:22])[CH3:21].B>O1CCCC1>[Br:1][C:2]1[CH:3]=[C:4]2[C:9](=[C:10]([CH2:12][N:13]([CH:16]3[CH2:18][CH2:17]3)[CH3:14])[CH:11]=1)[O:8][C:7]([CH3:20])([CH3:19])[CH2:6][C:5]2([CH3:22])[CH3:21]A solution of 6-bromo-8-[(cyclopropyl-formyl-amino)-methyl]-2,2,4,4-tetramethyl-chroman (Intermediate 8, 1.46 g, 4.0 mmol) in anhydrous tetrahydrofuran (30 mL) was treated with a 2M solution of borane:methylsulfide complex in tetrahydrofuran (5 mL, 10 mmol) and the resulting reaction mixture was refluxed for 2 h. It was then cooled in an ice bath, quenched cautiously with saturated aqueous sodium carbonate solution and extracted with diethyl ether. The organic phase was washed with water and brine, dried over anhydrous magnesium sulfate, filtered and evaporated in vacuo to afford the title product as a white solid (1.55 g, 100%).
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