Dimethylformamide → 2-Cephem

Participants

Reaction Steps

0.049 ml (0.388 mmol) of trimethylchlorosilane, 0.585 g (5.05 mmols) of 5-mercapto-1-methyltetrazole and 0.935 ml (5.43 mmols) of N-ethyl-N,N-diisopropylamine are added to a solution of 2.93 g (3.82 mmols) of 7β-(D-α-tert.butoxycarbonylamino-α-phenyl-acetylamino)-3-(p-toluenesulphonyloxy)-3-cephem-4-carboxylic acid diphenylmethyl ester in 11 ml of dimethylformamide. The red-brown solution is stirred for 16 hours at room temperature under nitrogen, diluted with ethyl acetate and purified by shaking with water, saturated aqueous sodium bicarbonate solution, 1 M sulphuric acid and saturated aqueous sodium chloride solution. The organic phase is dried over sodium sulphate and evaporated in vacuo. After drying the residue in a high vacuum, a mixture consisting of 7β-(D-α-tert.butoxycarbonylamino)-α-phenyl-acetylamino) 3-(1-methyl-5-tetrazolylthio)-3-cephem-4-carboxylic acid diphenylmethyl ester and the corresponding isomeric 2-cephem compound results and shows 2 spots in a thin layer chromatogram: silica gel (toluene/ethyl acetate, 2:1): Rf=0.13 (3-cephem compound); Rf=0.07 (2-cephem compound); IR spectrum of the crude product (CHCl3): characteristic bands at 3400, 1780, 1730-1690 (broad), 1495 and 1370 cm-1.

Provenance & Evidence