Triethylamine → Methyl alpha-[4-benzyloxycarbonylthio-3-phthalimido-2-oxoazetidin-1-yl]-alpha-(1-benzyloxycarbonylethylidene)acetate

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Reaction Conditions

Reaction Steps

To a solution of methyl α-[4-mercapto-3-phthalimido-2-oxoazetidin-1-yl]-α-(1-hydroxyethylidene)acetate (100 mg) in tetrahydrofuran (3 ml) is added benzyl chloroformate (100 mg), and the mixture is cooled to -65° C. To the solution is added triethylamine (60 mg) and stirred for 1 hour. After warming to room temperature, the mixture is evaporated. Purification of the residue by chromatography over silica gel gives methyl α-[4-benzyloxycarbonylthio-3-phthalimido-2-oxoazetidin-1-yl]-α-(1-benzyloxycarbonylethylidene)acetate (160 mg). Yield: 94%. The product contains no isomer at position α. IR: νmaxCHCl3 1790, 1780, 1730 cm-1. NMR: δCDCl3 8.00-7.50m4H, 7.40s5H, 7.30s5H, 6.27d(5 Hz)1H, 5.90d(5 Hz)1H, 5.27s2H, 5.17s2H, 3.70s3H, 2.47s3H.

Provenance & Evidence