Water → 3-[(E)-1-cyclopropylmethyl-2-oxo-pyrrolidin-3-ylidenemethyl]-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid triethylammonium salt

Participants

Reaction Conditions

Reaction Steps

To a stirred suspension of 22.78 g (E)-(6R,7R)-7-amino-3-(1-cyclopropylmethyl-2-oxo-pyrrolidin-3-ylidenemethyl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid (65.2 mmol) in 160 ml dimethylformamide was added under argon 9.1 ml triethylamine (65.2 mmol) at 10° C. After 30 min, to the solution was added 48 ml 2-propanol and 3.9 ml water causing the starting material to precipitate partially. The suspension was cooled to 2° C. and over 5 min was added in portions 36.68 g activated ester (Z)-(2-Aminothiazol-4-yl)-trityloxyiminoacetic acid diethoxythiophosphoryl ester (66.5 mmol). Stirring was continued at room temperature with exclusion of light for 17 h. The reaction was followed by HPLC. To the slightly turbid reaction mixture was added over 2 min 9.2 ml triethylamine (65.2 mmol, 1.0 eq) resulting in a clear, yellow solution. Reference material was added and after ca. 15 min, the reaction mixture became turbid, indicating the onset of crystallization. Stirring at room temperature was continued for 60 min and then 330 ml ethylacetate was added dropwise over 90 min. To drive crystallization to completion the suspension was cooled to 2° C. and stirred for 3 h at this temperature. The suspension was filtered. The crystalline product was washed with 3×100 ml ice-cold ethylacetate and dried to constant weight. The cephalosporin (6R, 7R)-7-[(Z)-2-(2-Aminothiazol-4-yl)-2-trityloxyimino-acetylamino)]-3-[(E)-1-cyclopropylmethyl-2-oxo-pyrrolidin-3-ylidenemethyl]-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid triethylammonium salt was obtained as an off-white solid (51.56 g, yield=77%, HPLC=100 area %) and was stored under Ar at 4° C. No further purification was necessary and the product was used as isolated for the next step.

Provenance & Evidence