1-(2-sulfanylidene-1,3-thiazolidin-3-yl)propan-1-one

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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). the reaction mixture was stirred at -20° C. for 15 hours the precipitated white mass was removed The organic layer was separated washed with 10% aqueous sodium chloride solution (30 ml×2) The organic solution was dried over magnesium sulfate evaporated The residue was chromatographed on silica gel (21 g) eluting with a mixture of acetone and dichloromethane (2:98, V/V)

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of stannous trifluoromethanesulfonate (8.35 g) and N-ethylpiperidine (3.79 ml) in dichloromethane (60 ml) was added dropwise a solution of 3-propionyl-2-thioxothiazolidine (4.12 g) in dichloromethane (35 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 (2.25 g) in dichloromethane (8 ml) was added to the reaction mixture, and the reaction mixture was stirred at 0° C. for 30 minutes and then at room temperature for 20 minutes. The reaction mixture was poured into aqueous sodium bicarbonate solution (100 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 (100 ml×2). The organic solution was dried over magnesium sulfate and evaporated. The residue was chromatographed on silica gel (185 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 (2.39 g). the reaction mixture was stirred at 0° C. for 30 minutes at room temperature for 20 minutes the precipitated white mass was removed The organic layer was separated washed with 10% aqueous sodium chloride solution (100 ml×2) The organic solution was dried over magnesium sulfate evaporated The residue was chromatographed on silica gel (185 g) eluting with a mixture of acetone and dichloromethane (2:98, V/V)