Toluene → (Rac)-4-(3-hydroxy-1-methoxycarbonyl-propyl)-5-oxo-[1,4]diazepane-1-carboxylic acid benzyl ester

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Reaction Steps

A solution of 1.53 g (3.20 mmol) of (rac)-4-[3-(tert-butyl-dimethyl-silanyloxy)-1-methoxycarbonyl-propyl]-5-oxo-[1,4]diazepane-1-carboxylic acid benzyl ester (evaporated twice with toluene) in 25 ml of dichloromethane was treated at 0° C. with 3.20 ml (3.20 mmol, 1 M in dichloromethane) of boron trichloride and kept 1 h at this temperature. The solution was stirred 17 h at room temperature and then extracted with cold sat. aq. sodium hydrogencarbonate solution and ethyl acetate (3×). The organic phases were washed with sat. aq. sodium hydrogencarbonate solution, 10% aq. sodium chloride solution, dried over Na2SO4 evaporated to give 1.34 g (quantitative) of the title compound as yellow viscous oil. MS: 365.1 (MH+).

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