Abstract: 6-[.alpha.-(Imidazolidin-2-on-1-ylcarbonylamino)-substutited acetamido]penicillanic acids, and the correspondingly 7-substituted ceph-3-em-4-carboxylic acids, characterized by the presence of a methyleneamino or substituted methyleneamino group on the 3-nitrogen atom of the imidazolidine ring are antibacterial agents. The compounds, of which 6-[.alpha.-(3-benzaliminoimidazolidin-2-on-1-ylcarbonylamino)cyclohe xa-1,4-dien-1-ylacetamido]penicillanic acid and 7-[.alpha.-(3-furylideneaminoimidazolidin-2-on-1-ylcarbonylamino)phenylace tamido]-3-(3-methylthiadiazol-5-ylthiomethyl)ceph-3-em-4-carboxylic acid are typical examples, are prepared through acylation of an 6-[.alpha.-(amino)substituted acetamido]penicillanic acid or the corresponding 7-[.alpha.-(amino)substituted acetamido]ceph-3-em-4-carboxylic acid with a reactive nucleofugic derivative of a 3-methyleneaminoimidazolidin-2-on-1-carboxylic acid.

Abstract: Cephalosporins of the formula ##STR1## their pharmaceutically-acceptable, nontoxic salts, and hydrates thereof are produced, whereinA is hydrogen; unsubstituted or substituted alkyl; aryl; or R.sub.1 --X--, whereinX is --CO-- or --SO.sub.2 --, andR.sub.1 is hydrogen, unsubstituted or substituted alkyl; aryl; thienyl; furyl; amino; alkylamino; dialkylamino; pyrrolidyl; or piperidyl;Or whenX is --CO--,R.sub.1 can also be alkoxy;B is phenyl, methylphenyl, chlorophenyl, hydroxyphenyl or the moiety ##STR2## E is hydrogen, hydroxyl or acetoxy; and C is a center of chirality.These compounds are particularly useful for their antimicrobial and, particularly, antibacterial effects.

Abstract: Cephalosporins of the formula ##STR1## their pharmaceutically-acceptable, nontoxic salts, and hydrates thereof are produced, whereinA is hydrogen; unsubstituted or substituted alkyl; aryl; or R.sub.1 --X--, whereinX is -CO- or -SO.sub.2 -, andR.sub.1 is hydrogen, unsubstituted or substituted alkyl; aryl; thienyl; furyl; amino; alkylamino; dialkylamino; pyrrolidyl; or piperidyl;Or whenX is -CO-,R.sub.1 can also be alkoxy;B is phenyl, methylphenyl, chlorophenyl, hydroxyphenyl or the moiety ##STR2## E is hydrogen, hydroxyl or acetoxy; and C is a center of chirality.These compounds are particularly useful for their antimicrobial and, particularly, antibacterial effects.

Abstract: Penicillin and cephalosporin derivatives characterized by the presence of a nitroalkyl, nitrocycloalkyl, nitrophenylalkyl or nitroanilinoalkyl group in the side chain are antibacterial agents. The compounds, of which 6-(2-nitro-3,3-dimethylbutyrylamido)-penicillanic acid, 7-nitroacetamido-3-methyl-ceph-3-em-4-carboxylic acid, and 6-[D-.alpha.-(2-nitro-2-methylpropionylamido)phenylacetamido]-penicillanic acid are typical embodiments, are prepared by reacting 6-amino-penicillanic acid, 7-amino-cephalosporanic acid (or derivative thereof) or an .alpha.-substituted-.alpha.-amino-acetamido-penicillanic acid with an appropriate nitrated carboxylic acid or an equivalent nitrated acylating agent.

Abstract: Cephalosporins of the formula ##STR1## their pharmaceutically-acceptable, nontoxic salts, and hydrates thereof are produced, whereinA is hydrogen; unsubstituted or substituted alkyl; aryl; or R.sub.1 --X--, whereinX is --CO-- or --SO.sub.2 --, andR.sub.1 is hydrogen, unsubstituted or substituted alkyl; aryl; thienyl; furyl; amino; alkylamino; dialkylamino; pyrrolidyl; or piperidyl;Or whenX is --CO--,R.sub.1 can also be alkoxy;B is phenyl, methylphenyl, chlorophenyl, hydroxyphenyl or the moiety ##STR2## E is hydrogen, hydroxyl or acetoxy; and C is a center of chirality.These compounds are particularly useful for their antimicrobial and, particularly, antibacterial effects.

Abstract: Penicillin and cephalosporin derivatives characterized by the presence of a nitroalkyl, nitrocycloalkyl, nitrophenylalkyl or nitroanilinoalkyl group in the side chain are antibacterial agents. The compounds, of which 6-(2-nitro-3,3-dimethylbutyrylamido)-penicillanic acid, 7-nitroacetamido-3-methyl-ceph-3-em-4-carboxylic acid, and 6-[D-.alpha.-(2-nitro-2-methylpropionylamido)phenylacetamido] pencillanic acid are typical embodiments, are prepared by reacting 6-amino-penicillanic acid, 7-amino-cephalosporanic acid (or derivative thereof) or an .alpha.-substituted-.alpha.-amino-acetamido-penicillanic acid with an appropriate nitrated carboxylic acid or an equivalent nitrated acylating agent.

Abstract: Penicillin and cephalosporin derivatives characterized by the presence of a nitroalkyl, nitrocycloalkyl, nitrophenylalkyl or nitroanilinoalkyl group in the side chain are antibacterial agents. The compounds, of which 6-(2-nitro-3,3-dimethylbutyrylamido)-penicillanic acid, 7-nitroacetamido-3-methyl-ceph-3-em-4-carboxylic acid, and 6-[D-.alpha.-(2-nitro-2-methylpropionylamido)phenylacetamido]-penicillanic acid are typical embodiments, are prepared by reacting 6-amino-penicillanic acid, 7-amino-cephalosporanic acid (or derivative thereof) or an .alpha.-substituted-.alpha. -aminoacetamido-penicillanic acid with an appropriate nitrated carboxylic acid or an equivalent nitrated acylating agent.