Disclosed are antibiotic cephalosporins (I) of the formula: ##STR1## Wherein the stylized radical attached to the 7-amino nitrogen of the cephalosporin moiety represents a nitrogen-containing heterocyclic group (mono- or polycyclic); R is, inter alia, hydrogen, alkyl, heterocyclylalkyl, aryl, alkenyl, aralkyl, --NR.sub.2, --OR, COOR, CONR.sub.2 or CN; A is conventionally known in the cephalosporin art; and R.sup.2 is H, or lower alkoxyl. Also disclosed are the pharmaceutically acceptable salt and ester derivatives of I; processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions when an antibiotic effect is indicated.

A process for the preparation of azetidinone-thiazoline precursors for cephalosporin synthesis. Said precursors are obtained by reducing by means of zinc dust in the presence of aqueous acetic acid a compound of formula ##STR1##

Disclosed are N-alkylated derivatives of thienamycin sulfoxide (I, n=1) and sulfone (I, n=2): ##STR1## wherein n=1 or 2; and R.sup.5, R.sup.6, and R.sup.7 are, inter alia, hydrogen or alkyl. Such compounds the their pharmaceutically acceptable O- and carboxyl- derivatives are useful as antibiotics. Also disclosed are processes for the preparation of such derivatives, pharmaceutical compositions comprising such derivatives and methods of treatment comprising administering such derivatives and compositions when an antibiotic effect is indicated.

Disclosed are substituted N-methylene derivatives of thienamycin sulfoxide (I, n=1) and sulfone (I, n=2) which may be represented by the following structural formula: ##STR1## wherein X and Y are selected from the group consisting of hydrogen, R, OR, SR, and NR.sup.1 R.sup.2 wherein, inter alia, R is substituted or unsubstituted: alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl, heterocyclyl, and heterocyclylalkyl; R.sup.1 and R.sup.2 are hydrogen or R. Such compounds and their pharmaceutically acceptable salt, ether, ester and amide derivatives are useful as antibiotics. Also disclosed are processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions when an antibiotic effect is indicated.

A process for producing a 2-cephem or 3-cephem derivative compound of the formula: ##SPC1## Wherein R.sub.1 represents a substituted or unsubstituted amino radical and R.sub.4 represents hydrogen or a radical selected from the group consisting of carboxy, protected carboxy, ester, acid amide, acid anhydride, acid halide, acid azide and carboxy salt, and the dotted line indicates the alternate bond structure providing 3-cephem or 2-cephem, which comprises: Reacting a halogenated derivative selected from the group consisting of a halogenated penam derivative having the formula: ##SPC2## A halogenated cepham derivative of the formula: ##SPC3## Wherein X represents a halogen atom, R.sub.3 represents a radical selected from the group consisting of carboxy, protected carboxy, ester, acid amide, acid anhydride, acid halide, acid azide and carboxy salt, and R.sub.1 is as defined above, or mixtures thereof with a dehydrohalogenoic acid reagent.