1,1-Dimethyl-2-thiourea → 2-Benzhydryloxycarbonyl-7-t-butoxycarbonylamino-3-(2-dimethylamino-thiazol-5-yl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene

Participants

Reaction Steps

The working method of Example 2 is followed, but replacing the thiourea by N,N-dimethylthiourea (5.25 g) and starting with 2-benzhydryloxycarbonyl-7-t-butoxycarbonylamino-3-(2-dimethylamino-vinyl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene (E-form) (21.4 g). The product obtained is chromatographed on a column (diameter: 4.5 cm) containing silica gel (0.2-0.06 mm)(500 cc), elution being carried out with methylene chloride (5 liters) and then with mixtures of methylene chloride and ethyl acetate, namely 99:1 by volume (5 liters) followed by 97:3 by volume (7.5 liters), and 500 cc fractions being collected; fractions 13 to 34 are concentrated to dryness under reduced pressure (30 mm Hg; 4 kPa) at 30° C. The residue is triturated with isopropyl ether (100 cc) and 2-benzhydryloxycarbonyl-7-t-butoxycarbonylamino-3-(2-dimethylamino-thiazol-5-yl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene (13.8 g) is obtained in the form of a yellow solid.

Provenance & Evidence