[Br:1][C:2]1[CH:3]=[C:4]([CH:7]=O)[O:5][CH:6]=1.[CH3:9][N:10]1[CH2:15][CH2:14][NH:13][CH2:12][CH2:11]1.C(O[BH-](OC(=O)C)OC(=O)C)(=O)C.[Na+].C(O)(=O)C.[OH-].[Na+]>O.C1COCC1>[Br:1][C:2]1[CH:3]=[C:4]([CH2:7][N:13]2[CH2:14][CH2:15][N:10]([CH3:9])[CH2:11][CH2:12]2)[O:5][CH:6]=1
To a stirred mixture of 4-bromofuran-2-carbaldehyde (2.10 g, 12.0 mmol) and THF (10 mL) that was cooled in an ice bath was added 1-methylpiperazine (1.60 ml, 14.4 mmol) dropwise, followed by sodium triacetoxyborohydride (3.81 g, 18.0 mmol) in 3 portions as solid. Acetic acid (0.343 ml, 6.00 mmol) was added, and the reaction was stirred for 18 hours at ambient temperature. The dark mixture was diluted with water (10 mL) and basified to pH>12 by addition of 5N NaOH. The mixture was extracted with diethyl ether (3×50 mL). The combined organic phases were dried (Na2SO4), filtered, and concentrated in vacuo. The resulting black oil (2.10 g, 66%) was carried forward without purification.
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