Dimethylformamide dimethyl acetal → 2-Benzhydryloxycarbonyl-7-t-butoxycarbonylamino-3-(2-dimethylaminomethyleneamino-thiazol-5-yl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene

Participants

Reaction Conditions

Reaction Steps

A solution of 3-(2-amino-thiazol-5-yl)-2-benzhydryloxycarbonyl-7-t-butoxycarbonylamino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene (4 g) in tetrahydrofuran (50 cc) is treated with dimethoxy(dimethylamino)methane (1.13 g). The reaction mixture is stirred for 25 minutes at 20° C., then diluted with ethyl acetate (150 cc), washed with distilled water (4×150 cc) and with a saturated sodium chloride solution (150 cc) and dried ove magnesium sulphate. The residue obtained after evaporation of the solvent under reduced pressure (30 mm Hg; 4 kPa) at 30° C. is chromatographed on a column (height: 28 cm; diameter: 5 cm) of silica gel (0.04-0.06 mm), elution being carried out under a pressure of 0.6 bar (60 kPa) with ethyl acetate, and 100 cc fractions being collected. Fractions 9 to 23, containing the pure product, are combined and concentrated to dryness under reduced pressure (30 mm Hg; 4 kPa) at 30° C. 2-Benzhydryloxycarbonyl-7-t-butoxycarbonylamino-3-(2-dimethylaminomethyleneamino-thiazol-5-yl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene (E-form) (2.25 g) is obtained in the form of an orange froth whose characteristics are identical to those of the product obtained in A.

Provenance & Evidence