Sodium Phosphate, Dibasic → Methyl cis-3-t-butoxycarbonylamino-4-oxoazetidine-2-carboxylate

Beteiligte Stoffe

Reaktionsschritte

A solution of 10.5 g (26.7 mmole) of methyl 3-t-butoxycarbonylamino-1-(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate in 500 ml of acetonitrile is degassed with argon and warmed to 80°. A degassed solution of 15 g (55.5 mmole) of potassium persulfate and 7.5 g (28 mmole) of sodium monohydrogen phosphate in 150 ml of water is added in five portions over 1 hr. The reaction is stirred at 80°-85° under argon for 2-3 hrs until all starting material is consumed (tlc). The reaction mixture is cooled, concentrated in vacuum, shaken with ethyl acetatewater. The organic phase is washed with dilute HCl, NaHCO3 solution and brine; dried over magnesium sulfate and evaporated to dryness. The residue is chromatographed over silica gel with 1:1 benzene-ethyl acetate to afford pure product which crystallized from ethyl acetate-hexane to yield 2.0 g (31%) of the title compound. A less pure fraction from the column, is crystallized from ethyl acetate-hexane to give an additional 0.5 g of product, overall yield, 38%.

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