Abstract: A cephalosporin derivative of the formula ##STR1## wherein R is a hydrogen atom, a lower alkyl group which may have been substituted or a carbamoyl group which may have been substituted; R.sub.1 is hydrogen atom or a methoxy group; R.sub.2 is a hydrogen atom, an acyloxy group, or a nitrogen-containing 5-membered heterocyclic thio group which may have been substituted; R.sub.3 is a free amino group or an amino group having a protective group; and R.sub.4 is a free carboxy group or a carboxy group having a protective group or the salts thereof.The compound of this invention has an excellent antibacterial activity against gram negative bacteria and gram positive bacteria.

Abstract: Substituted 1,3-dithietane-2-carboxylic acid derivatives useful as intermediates for the preparation of highly effective penicillin and cephalosporin derivatives and the preparation thereof.

Abstract: The invention relates to novel 7.alpha.-methoxycephalosporin derivatives having at the 7.beta.-position an amido group acylated by a 1,3-dithietane carboxylic acid residue and to 7.beta.-isothiazolylthioacetamido-7.alpha.-methoxycephalosporins having antibacterial activity by themselves and, as the case may be, capable of being converted into the aforesaid 7.alpha.-methoxycephalosporin derivatives. The compounds of this invention exhibit excellent antibacterial activity and are particularly effective against gram negative bacteria.

Abstract: The invention relates to novel 7.alpha.-methoxycephalosporin derivatives having at the 7.beta.-position an amido group acylated by a 1,3-dithietane carboxylic acid residue and to 7.beta.-isothiazolylthioacetamido-7.alpha.-methoxycephalosporins having antibacterial activity by themselves and, as the case may be, capable of being converted into the aforesaid 7.alpha.-methoxycaphalosporin derivatives. The compounds of this invention exhibit excellent antibacterial activity and are particularly effective against gram negative bacteria.

Abstract: Process for producing 7.beta.-amino-7.alpha.-methoxycephalosporins without the epimerization or formation of the corresponding 7.alpha.-amino-7.beta.-methoxy isomers by deacylating cephalosporin derivatives having 7.beta.-acylamino-7.alpha.-methoxy group.

Abstract: Substituted 1,3-dithietane-2-carboxylic acid derivatives useful as intermediates for the preparation of highly effective penicillin and cephalosporin derivatives and the preparation thereof.

Abstract: Novel 7.alpha.-methoxy-7.beta.-heterocyclic thioacetamido-3-heterocyclic thiomethyl-.DELTA..sup.3 -cephem-4-carboxylic acid derivatives and pharmaceutically acceptable salts thereof. These compounds show high antibiotic activities against various microorganisms including gram positive and negative bacteria.

Abstract: A novel cephalosporin derivative having at the 3-position of the cephem ring a heterocyclic thiomethyl group having a carboxy group or a sulfo group and at the 7-position of the cephem ring, an .alpha.-heterocyclic acylaminophenylacetamide group. The compounds of this invention have excellent antibacterial activity against Pseudomonas and Proteus strains of bacteria.

Abstract: Novel 7-(.alpha.-hydroxy-substituted pyridylcarboxamido-.alpha.-phenylacetamido)-3-substituted thiomethyl-.DELTA..sup.3 -cephem-4-carboxylic acid derivatives are disclosed. The compounds of this invention have high water solubility and show excellent antibacterial activities against various strains of Pseudomonas and Proteus.

Abstract: N-alkenyltetracycline derivatives, for example, N-(1-methyl-2-.alpha.-naphthylethenyl)tetracycline represented by the formula ##SPC1##The compounds have excellent antibacterial action as compared with tetracycline.

Abstract: There are provided novel 1,4-dihydropyridine derivatives, particularly 2,6-dimethyl-4-(3'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester and 5-methyl ester. The 1,4-dihydropyridine derivatives are characterized by cerebral vascular dilator activity.

Abstract: N-alkenyltetracycline derivatives, for example, N-[1-methyl-2(2-thienyl)-1-butenyl]tetracycline represented by the formula ##SPC1##The compounds have excellent antibacterial action as compared with tetracycline.

Abstract: The invention relates to novel 7.alpha.-methoxycephalosporin derivatives having at the 7.beta.-position an amido group acylated by a 1,3-dithietane carboxylic acid residue and to 7.beta.-isothiazolylthioacetamido-7.alpha.-methoxycephalosporins having antibacterial activity by themselves and, as the case may be, capable of being converted into the aforesaid 7.alpha.-methoxycephalosporin derivatives. The compounds of this invention exhibit excellent antibacterial activity and are particularly effective against gram negative bacteria.

Abstract: Substituted 1,3-dithietane-2-carboxylic acid derivatives useful as intermediates for the preparation of highly effective penicillin and cephalosporin derivatives and the preparation thereof.