Abstract
A novel direct introduction of a formamido group into the 7α(6α)-position of cephalosporins (penicillins) was achieved by treatment of 7β(6β-[(3, 5-di-tert-butyl-4-oxo-2, 5-cyclohexadien-1-ylidene)methylimino]cephem (penam) esters with N, N-bis(trimethylsilyl)formamide, followed by deblocking with Girard reagent T to give the corresponding 7α(6α)-foimamido-7β(6β-amino derivatives. Three 7α-formamidocephalosporins were prepared by the conventional N-acylation of 7α-formamidocephem. All of them were resistant to β-lactamases, showing similar MIC values against both of a pair of a β-lactamase-producing strain and the corresponding non or low-producing strain of the same species of bacteria, when tested on Staphylococcus aureus, Klebsiella pneurnoniae, Escherichia coli, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Enterobacter cloacae and Citrobacter freundii.
