N-Ethylpiperidine → (3S,4R)-3-[(1R)-1-(t-butyldimethylsilyloxy)ethyl]-4-[(1RS)-1-methyl-2-oxo-2-(2-thioxothiazolidin-3-yl)ethyl]-2-azetidinone

Participants

Reaction Conditions

Reaction Steps

To a suspension of stannous trifluoromethanesulfonate (1.63 g) and N-ethylpiperidine (0.827 ml) in dichloromethane (12 ml) was added dropwise a solution of 3-propionyl-2-thioxothiazolidine (1.07 g) in dichloromethane (9 ml) at -78° C. under nitrogen atmosphere. After stirring at -78° C. for 30 minutes, a solution of (3R,4R)-4-acetoxy-3-[(1R)-1-(t-butyldimethylsilyloxy)ethyl]-2-azetidinone (0.876 g) and zinc bromide (1.37 g) in dichloromethane (3 ml) was added to the reaction mixture, and the reaction mixture was stirred at -20° C. for 15 hours. The reaction mixture was poured into aqueous sodium bicarbonate solution (30 ml) and the precipitated white mass was removed by passing through a layer of Celite. The organic layer was separated and washed with 10% aqueous sodium chloride solution (30 ml×2). The organic solution was dried over magnesium sulfate and evaporated. The residue was chromatographed on silica gel (21 g) eluting with a mixture of acetone and dichloromethane (2:98, V/V) to give (3S,4R)-3-[(1R)-1-(t-butyldimethylsilyloxy)ethyl]-4-[(1RS)-1-methyl-2-oxo-2-(2-thioxothiazolidin-3-yl)ethyl]-2-azetidinone (878 mg).

Provenance & Evidence