Synthesis and cytotoxic properties of derivatives of the tert-butyl ester of 7-alkylidene-3-methyl-3-cepheme-4-carboxylic acid

Sulfones of the tert-butyl esters of 7-arylmethylene-and 7-(2-furyl)methylene-3-methyl-3-cepheme-4-carboxylic acid were obtained by the condensation of the tert-butyl ester of 3-methyl-7-oxo-3-cepheme-4-carboxylic acid with arylmethylene-and 2-furylidenetriphenylphosphoranes and subsequent oxidation of the intermediate products by meta-chloroperbenzoic acid. The combination of the tert-butyl esters of 7E-bromomethylene-and 7,7-dibromomethylene-3-methyl-1,1-dioxo-3-cepheme-4-carboxylic acids with trimethylsilylacetylene under conditions of the Sonogashira reaction gave the tert-butyl esters of 3-methyl-1,1-dioxo-7E-(3-trimethylsilyl-2-propynylidene)-3-cepheme-4-carboxylic acid and 3-methyl-1,1-dioxo-7-1,5-bis(trimethylsilyl)-1,4-pentadiyn-3-ylidene]-3-cepheme-4-carboxylic acid. The Vilsmeier reagent was used to incorporate the dimethylaminomethylene group at C-2 of the 7Z-and 7E-isomers of the tert-butyl ester of 7-(4-chlorophenyl)methylene-3-methyl-1,1-dioxo-3-cepheme-4-carboxylic acid. The cytotoxic properties of the derivatives of the tert-butyl ester of 7-alkylidene-3-methyl-3-cepheme-4-carboxylic acid in regard to cancer and normal cells in vitro depends on the structure and 7Z-or 7E-isomerism of the substituent in the 7-alkylidene group as well as the presence of a dimethylaminomethylene group at C-2 of the 3-cepheme system.