N1([CH2:10][NH:11][CH:12]2[CH2:16][CH2:15][CH2:14][CH2:13]2)C2C=CC=CC=2N=N1.[Cl:17][C:18]([Cl:27])=[C:19]([O:25][CH3:26])[O:20][Si](C)(C)C.B(F)(F)F.CCOCC>ClCCl>[CH3:26][O:25][C:19](=[O:20])[C:18]([Cl:27])([Cl:17])[CH2:10][NH:11][CH:12]1[CH2:13][CH2:14][CH2:15][CH2:16]1To a solution of 4.3 g (0.02 mole) of benzotriazol-1-ylmethyl-cyclopentyl-amine and 6.4 g (0.030 mole) of (2,2-dichloro-1-methoxy-vinyloxy)-trimethyl-silane in 140 ml of anhydrous dichloromethane was added dropwise 3.7 ml (0.030 mole) of boron trifluride diethyl etherate at 0 degrees. The reaction was stirred at 0 degrees for 1 hour and then at room temperature for 24 hours. The reaction was quenched by the addition of 10% aqueous sodium carbonate and extracted with dichloromethane. The organic layer was washed with saturated sodium carbonate, brine, dried over sodium sulfate, filtered and concentrated under reduced pressure. Purification by silica gel chromatography, eluting with hexane-ethyl acetate (gradient, 100:0-85:15) gave 2.4 g of 2,2-dichloro-3-cyclopentylamino-propionic acid methyl ester as a colorless oil.
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