[NH2:1][CH:2]([CH2:5][CH2:6][CH2:7][C:8]1[CH:13]=[CH:12][C:11]([O:14][CH2:15][C@@H:16]2[CH2:20][O:19][C:18]([CH3:22])([CH3:21])[O:17]2)=[CH:10][CH:9]=1)[C:3]#[N:4].[CH3:23][O:24][C:25]1[CH:32]=[C:31]([O:33][CH3:34])[CH:30]=[CH:29][C:26]=1[CH:27]=O.C(O[BH-](OC(=O)C)OC(=O)C)(=O)C.[Na+].C(=O)([O-])O.[Na+]>C(Cl)Cl>[CH3:15][CH2:16][O:17][C:18]([CH3:21])=[O:19].[CH3:5][CH2:6][CH2:7][CH:8]([CH3:13])[CH3:9].[CH3:23][O:24][C:25]1[CH:32]=[C:31]([O:33][CH3:34])[CH:30]=[CH:29][C:26]=1[CH2:27][NH:1][CH:2]([CH2:5][CH2:6][CH2:7][C:8]1[CH:13]=[CH:12][C:11]([O:14][CH2:15][C@@H:16]2[CH2:20][O:19][C:18]([CH3:22])([CH3:21])[O:17]2)=[CH:10][CH:9]=1)[C:3]#[N:4]To a solution of 2-amino-5-[4-((R)-2,2-dimethyl-[1,3]dioxolan-4-ylmethoxy)-phenyl]-pentanenitrile (Intermediate B) (480 mg, 1.6 mmol) in DCM (13 mL) is added 2,4-dimethoxybenzaldehyde (319 mg, 1.92 mmol) and sodium triacetoxyborohydride (529 mg, 2.49 mmol) and the reaction is stirred at RT for 15 h. After this time saturated aqueous sodium hydrogen carbonate solution (20 mL) is added and the reaction is stirred at RT for 0.5 h. DCM (20 mL) is added and the layers are separated. The organic phase is washed with brine (20 mL) then dried over Na2SO4 and the solvent is removed in vacuo. Chromatography (SiO2, EtOAc:iso-hexane 2:3) affords the title compound as a colourless oil.
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