2, 4-Dimethyl -5 -nitrofuran -3 -carboxylic acid and its derivatives

It is found that 2, 4-dimethyl-5-nitrofuran-3-carboxylic acid and its methyl ester can give comparatively stable anionic groups, which are prepared electrochemically and investigated by EPR. Their lives (80–100 sec) are 4- 5 times greater than the lives of other anionic groups of the 5-nitrofuran series previously studied. Starting from 2, 4-dimethyl-5-nitrofuran-3-carboxylic acid and 2, 4-dimethylfuran-3-carboxylic acid, two new semisynthetic penicillins are prepared, with activities basically extending to Gram-positive microorganisms, including forms of staphylcocci resistant to benzylpenicillin. Introduction of the nitro group into the furan ring increases the stability of penicillin to acid 79-fold. Low toxicity penicillins are synthesized (LD₅₀ 1000–1500 mg/kg).