[Cl:1][C:2]1[CH:3]=[C:4]([CH:7]=[CH:8][C:9]=1[Cl:10])[CH:5]=O.Cl.[NH2:12][CH2:13][CH2:14][CH2:15][C:16]([N:35]([CH3:39])[C:36](=[O:38])[CH3:37])([CH2:22][CH2:23][CH2:24][CH2:25][B:26]1[O:30][C:29]([CH3:32])([CH3:31])[C:28]([CH3:34])([CH3:33])[O:27]1)[C:17]([O:19][CH2:20][CH3:21])=[O:18].C(O[BH-](OC(=O)C)OC(=O)C)(=O)C.[Na+]>ClCCl>[Cl:1][C:2]1[CH:3]=[C:4]([CH:7]=[CH:8][C:9]=1[Cl:10])[CH2:5][NH:12][CH2:13][CH2:14][CH2:15][C:16]([N:35]([CH3:39])[C:36](=[O:38])[CH3:37])([CH2:22][CH2:23][CH2:24][CH2:25][B:26]1[O:30][C:29]([CH3:31])([CH3:32])[C:28]([CH3:33])([CH3:34])[O:27]1)[C:17]([O:19][CH2:20][CH3:21])=[O:18]A solution of 3,4-dichlorobenzaldehyde (55 mg, 0.31 mmol) and ethyl 2-(3-aminopropyl)-2-(N-methylacetamido)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate hydrochloride (120 mg, 0.26 mmol) in dichloromethane (3 mL) was stirred at room temperature. After 30 min, sodium triacetoxyborohydride (138 mg, 0.65 mmol) was added in one portion and stirring was continuated overnight. Once complete, the solution was diluted with dichloromethane (10 mL), quenched with aq 5% NaHCO3 (W/V, 5 mL) and stirred vigorously for 30 min. The layers were separated and the organic phase was washed with water and sat'd aq sodium chloride, dried over MgSO4, filtered and concentrated. Purification by flash column chromatography (2-20% methanol in dichloromethane) gave ethyl 2-(3-(3,4-dichlorobenzylamino)propyl)-2-(N-methylacetamido)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate (78 mg). ESI MS found for C27H43BCl2N2O5 m/z [557.6/559.6 (M+1)].
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