Abstract: Novel cephalosporin compounds having antibacterial activity, which are represented by the following compounds of the general formula (I), ##STR1## wherein R.sub.1 represents an amino group or a protected amino group;.circle.A represents a 5- or 6-membered heterocyclic ring containing therein 1 to 4 nitrogen, oxygen or sulfur atoms;R.sub.2 represents a normal alkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms, an alkoxyalkyl group having 2 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms; a cycloalkenyl group having 3 to 6 carbon atoms; an aromatic organic residue; a 3- to 6-membered heterocyclic ring containing 1 to 4 nitrogen, sulfur or oxygen atoms or, ##STR2## wherein Ra and Rb each, which may be the same or different, represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;R.sub.

Abstract: A secalonic acid derivative of the formula (I); ##STR1## wherein R is ##STR2## wherein R.sub.1 and R.sub.2 each independently is a hydrogen atom or a C.sub.1-4 alkyl group; R.sub.3 is a hydrogen atom, a C.sub.1-4 alkyl group, and aryl group, a C.sub.1-5 alkoxy group, a halogen atom, a cyano group, a carboxyl group, a sulfonic acid group, a carboxylic acid amide group or a sulfonic acid amide group; and R.sub.4 is a saturated or unsaturated C.sub.1-22 alkyl group, an aryl group or an aryl alkyl group, and may have a substituent; and the pharmaceutically acceptable salts thereof.

Abstract: Novel thioesters effective as acylating agents for amines or hydrazines, especially effective as active esters in synthesis of cephalosporin compounds are disclosed. The novel thioester of the present invention can be prepared by reacting a thiol or a derivative thereof with an acetic acid derivative or a reactive derivative thereof. By reacting the thioester of the present invention with a 7-aminocephalosporin derivative or a salt thereof, cephalosporin derivatives or pharmacologically acceptable salts thereof which are excellent antibiotic substances having a high antimicrobial activity can be obtained in high yield very safely.

Abstract: Novel thioesters effective as acylating agents for amines or hydrazines, especially effective as active esters in synthesis of cephalosporin compounds are disclosed. The novel thioester of the present invention can be prepared by reacting a thiol or a derivative thereof with an acetic acid derivative or a reactive derivative thereof. By reacting the thioester of the present invention with a 7-aminocephalosporin derivative or a salt thereof, cephalosporin derivatives or pharmacologically acceptable salts thereof which are excellent antibiotic substances having a high antimicrobial activity can be obtained in high yield very safely.

Abstract: Novel thioesters effective as acylating agents for amines or hydrazines, especially effective as active esters in synthesis of cephalosporin compounds are disclosed. The novel thioester of the present invention can be prepared by reacting a thiol or a derivative thereof with an acetic acid derivative or a reactive derivative thereof. By reacting the thioester of the present invention with a 7-aminocephalosporin derivative or a salt thereof, cephalosporin derivatives or pharmacologically acceptable salts thereof which are excellent antibiotic substances having a high antimicrobial activity can be obtained in high yield very safely.

Abstract: A secalonic acid derivative of the formula (I); ##STR1## wherein R is ##STR2## wherein R.sub.1 and R.sub.2 each independently is a hydrogen atom or a C.sub.1-4 alkyl group; R.sub.3 is a hydrogen atom, a C.sub.1-4 alkyl group, an aryl group, a C.sub.1-5 alkoxy group, a halogen atom, a cyano group, a carboxyl group, a sulfonic acid group, a carboxylic acid amide group or a sulfonic acid amide group; and R.sub.4 is a saturated or unsaturated C.sub.1-22 alkyl group, an aryl group or an aryl alkyl group, and may have a substituent;and the pharmaceutically acceptable salts thereof.

Abstract: This invention relates to a tetrazole-5-thiol ester having D-configuration of the formula, ##STR1## a process for the preparation of the thiol ester and a process for the preparation of cefamandole using the thiol ester.

Abstract: This invention relates to a tetrazole-5-thiol ester having D-configuration of the formula, ##STR1## a process for the preparation of the thiol ester and a process for the preparation of cefamandole using the thiol ester.

Abstract: A method for preparing a cephalosporin compound represented by the general formula (III) ##STR1## (wherein R represents hydrogen or methyl group) or a pharmaceutically acceptable salt thereof, which is characterized by reacting 7-amino-3-(benzimidazol-2-yl)-thiomethyl-3-cephem-4-carboxylic acid represented by the general formula (I) ##STR2## or a salt thereof with a compound represented by general formula (II) ##STR3## wherein R represents hydrogen or methyl group.

Abstract: An 1,3,4-thiadiazole-5-thiol ester of the formula, ##STR1## wherein R is a hydrogen atom or a methyl group, a process for their preparation and a process for preparing a cephalosporin compound of the formula, ##STR2## wherein R is the same as defined above, using the above described 1,3,4-thiadiazole-5-thiol ester.

Abstract: An 1,3,4-thiadiazole-5-thiol ester of the formula, ##STR1## wherein R is a hydrogen atom or a methyl group, a process for their preparation and a process for preparing a cephalosporin compound of the formula, ##STR2## wherein R is the same as defined above, using the above described 1,3,4-thiadiazole-5-thiol ester.

Abstract: Novel cephalosporin derivatives having a higher antimicrobial activity across a broad antimicrobial spectrum. They are useful for treatment of infections caused by Gram-positive bacteria and Gram-negative bacteria. Such cephalosporin derivatives are prepared by a relatively simple method.

Abstract: Novel 7.alpha.-methoxycephalosporin derivatives having a high antimicrobial activity. They are useful for the medical treatment of diseases infected by gram-positive bacteria and gram-negative bacteria. More particularly, they show an antimicrobial activity against bacteria such as Eschericha coli Proteus, Citrobacter and Enterobacter which bacteria have resistance to the conventionally employed cephalosporins, and they are effective for the medical treatment of diseases infected by these bacteria. Such 7.alpha.-methoxycephalosporin derivatives are prepared by a relatively simple method.

Abstract: Novel cephalosporin derivatives having a higher microbial activity across a broad antimicrobial spectrum. They are useful for treatment of infections caused by Gram-positive bacteria and Gram-negative bacteria. Such cephalosporin derivatives are prepared by a relatively simple method.