Abstract: A process for the preparation of at least one compound of a formula selected from the group consisting of ##STR1## and their salts and esters wherein X is selected from the group consisting of hydrogen and a substituent such as halogen and acetoxy comprising diazotizing a compound of the formula ##STR2## and salts and esters thereof wherein X has the above definition and brominating the resulting diazotized compound with at least an equimolar amount of a nitrosating agent in the presence of 1 to 5 equivalents of a strong acid in solution or suspension in a mixture of water and an at least partially water-miscible organic solvent with the amount of water being 1 to 20% by volume containing at least equimolar amounts of hydrogen bromide and bromine which bromo compounds are useful intermediates for the preparation of penicillanic acid-1,1-dioxide and its derivatives and novel 6-diazo-intermediates.

Abstract: A process for the preparation of 7.beta.-acylamino-3-substituted-3-cephem-4-carboxylic acid compounds comprising reacting at -70.degree. C. to 0.degree. C. in an inert organic solvent phosphorus pentachloride with a cephalosporin compound in the presence of an olefinic compound having at least one carbon-carbon double bond having not more than three hydrogen atoms attached thereto capable of removing chlorine at least in part by addition to a carbon-carbon double bond.

Abstract: A process for the preparation of at least one compound of a formula selected from the group consisting of ##STR1## and their salts and esters wherein X is selected from the group consisting of hydrogen and a substituent such as halogen and acetoxy comprising diazotizing a compound of the formula ##STR2## and salts and esters thereof wherein X has the above definition and brominating the resulting diazotized compound with at least an equimolar amount of a nitrosating agent in the presence of 1 to 5 equivalents of a strong acid in solution or suspension in a mixture of water and an at least partially water-miscible organic solvent with the amount of water being 1 to 20% by volume containing at least equimolar amounts of hydrogen bromide and bromine which bromo compounds are useful intermediates for the preparation of penicillanic acid-1,1-dioxide and its derivatives and novel 6-diazo-intermediates.

Abstract: A process for the preparation of penicillanic acid-1,1-dioxides of the formula ##STR1## wherein X is selected from the group consisting of hydrogen and substituent such as halogen or acetoxy and R is selected from the group consisting of hydrogen, a pharmaceutically acceptable metal ion and/or ester radical comprising debrominating a 6-.alpha.-bromo- and/or 6,6-dibromo-penicillanic 1,1-dioxide selected from the group consisting of the formula ##STR2## wherein X and R have the above definition in an aqueous containing medium with zinc in association with an acid having a pK.sub.a -value measured in water less than 3.5 and optionally if R is H converting the acid into a pharmaceutically acceptable salt or ester.

Abstract: A process for the preparation of [D-.alpha.-amino-p-hydroxyphenylacetamido]-penicillanic acid or cephalosporanic acid compounds comprising reacting a compound having a formula selected from the group consisting of ##STR1## wherein X is selected from the group consisting of hydrogen, acetoxy and five-membered heterocyclic group containing at least one hetero atom of the group consisting of oxygen, sulfur and nitrogen and optionally substituted with e.g. lower alkyl, this residue being attached to the 3-CH.sub.2 group via sulfur atom and wherein a NH radical if present has optionally been silylated with at least one mole equivalent of a silylating agent producing ##STR2## wherein R.sub.1, R.sub.2 and R.sub.

Abstract: 1,2,4-Oxadiazolylacetic acid derivatives. The derivatives include penicillin and cephalosporin amides which have antibiotic properties.

Abstract: A process for the preparation of 6-(D-.alpha.-amino-p-hydroxyphenylacetamido)-penicillanic acid or amoxicillin by reacting 6-aminopenicillanic acid with at least two equivalents of a silylating agent producing trimethylsilyl groups in an anhydrous, inert, water-insoluble organic solvent and reacting the resulting product at a temperature below -25.degree. C with an at least equimolar amount of a compound of the formula ##STR1## wherein R.sub.1 and R.sub.7 are lower alkoxy, R.sub.2 is lower alkyl and R.sub.3 is selected from the group consisting of lower alkyl and hydrogen previously prepared from the corresponding Dane salt and an acid chloride under anhydrous conditions in the presence of a tertiary amine in an inert, water-insoluble organic solvent.