[CH:1]1([NH2:4])[CH2:3][CH2:2]1.[Si:5]([O:12][CH2:13][CH:14]=O)([C:8]([CH3:11])([CH3:10])[CH3:9])([CH3:7])[CH3:6].[BH4-].[Na+].Cl[CH:19](Cl)[CH3:20]>C(O)(=O)C>[Si:5]([O:12][CH2:13][CH2:14][NH:4][CH:1]1[CH2:20][CH2:19][CH2:2][CH2:3]1)([C:8]([CH3:11])([CH3:10])[CH3:9])([CH3:7])[CH3:6]To a stirred solution of cyclopropylamine (1 g, 13.15 mmol) in dichlorethane (20 mL) were added 2-(tert-butyl-dimethylsilanyloxy)acetaldehyde (2.3 mg, 2.30 mmol) and acetic acid (0.08 mL, 0.29 mmol) at 0° C. Stirring was continued for 24 h at room temperature and NaBH4 (995 mg, 26.29 mmol) was added portion-wise at 0° C. The reaction mixture was further stirred for 2 h at room temperature, quenched with water and extracted with dichloromethane (3×30 mL). The organic part was dried and concentrated to yield a crude product which was purified by Combi-Flash column (eluted at 10-20% ethyl acetate in hexane) to get [2-(tert-butyl-dimethylsilanyloxy)-ethyl]-cyclopentylamine (8e) (1.2 g, 37.48%) as a yellow oil.
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