Carbon Disulfide → p-Nitrobenzyl 2-(4-methylthio-2-azetidinon-1-yl)-2-(4-oxo-1,3-dithietan-2-ylidene)acetat

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Reaction Steps

To a solution of 740 μl hexamethyldisilazane in 12 ml of tetrahydrofuran was added a solution of butyllithium in hexane (2.4 ml, 163 mmoles/ml) at room temperature, and then the mixture was stirred for 30 minutes. A solution of 620 mg of p-nitrobenzyl 2-(4-methylthio-2-azetidinon-1-yl)acetate in 8 ml of tetrahydrofuran was then added, after cooling the mixture of -78° C., after which it was stirred for 5 minutes. To the resulting solution was added carbon disulphide (181.2 μl), and the mixture was stirred for 20 minutes. A solution of phosgene (198 mg) in benzene (468 μl) was added to the solution, and stirring was continued at -78° C. for 1 hour. Acetic acid (680 μl) was added to the reaction mixture. The resulting mixture was diluted with ethyl acetate, washed successively with water and an aqueous solution of sodium chloride, and dried over anhydrous sodium sulphate. The solvent was distilled off under reduced pressure and the resulting residue was purified by column chromatography (eluent: a 4:1 by volume mixture of benzene and ethyl acetate), to give 703 mg of the desired compound as a foamy substance.

Provenance & Evidence