Water → (3S)-3-[(1R)-1-(t-butyldimethylsilyloxy)ethyl]-1-(4-methoxybenzyl)azetidin-2-one

Participants

Reaction Steps

To a solution of ethyl (2S*,3R*)-3-(t-butyldimethylsilyloxy)-2-(4-methoxybenzylaminomethyl)butanoate (6 g) in tetrahydrofuran (303 ml) was added dropwise a solution of mesitylmagnesium bromide (1M, 24.3 ml) in tetrahydrofuran at room temperature. After stirring for 30 minutes, water (10 ml) was added dropwise to the reaction mixture and the solvent was removed under reduced pressure. To the residue were added ethyl acetate and water, then the aqueous layer was separated and extracted twice with ethyl acetate. The combined organic layers were washed with 1N hydrochloric acid, saturated aqueous sodium hydrogencarbonate, water and an aqueous sodium chloride in turn and then dried over magnesium sulfate. The resultant solution was evaporated under reduced pressure and the residue was column-chromatographed on silica gel (eluent : a mixture of hexane and ethyl acetate, 3:1) to give (3S*)-3-[(1R*)-1-(t-butyldimethylsilyloxy)ethyl]-1-(4-methoxybenzyl)azetidin-2-one (4.8 g), which contained about 2% of the corresponding (3R*), (1R*)-isomer.

Provenance & Evidence