Abstract: There are disclosed novel antibacterial compounds having the formula ##STR1## wherein R is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, cyclo lower alkyl, aryl of 6-12 carbon atoms, all the said foregoing groups being optionally substituted with carboxy, lower alkoxycarbonyl, phenoxycarbonyl, amino, mono- or di-lower alkyl substituted amino, hydroxy, lower alkoxy, phenoxy, carbamoyl, lower alkyl carbonyl, benzoyl, cyano, nitro, formamido, lower alkanoylamino or benzamido;R.sup.1 is hydrogen, lower alkyl or an alkali metal cation;A is lower alkoxy, lower alkenoxy, lower alkynoxy, aryloxy of 6-12 carbon atoms, di-lower alkyl substituted amino, di-lower alkenyl substituted amino, di-lower alkynyl substituted amino, di-aryl of 6-12 carbon atoms substituted amino, lower alkyl, lower alkenyl, lower alkynyl, aryl of 6-12 carbon atoms.

Abstract: 7-[2-(3-Amino-5-isoxazolyl)-2-alkyloxyiminoacetamido]-ceph-3-em-4-carboxyli c acid derivatives are antibacterial agents effective against gram-positive and gram-negative bacterium.

Abstract: 7-[2-(3-Amino-5-isoxazolyl)-2-alkyloxy-iminoacetamido]-ceph-3-em-4-carboxyl ic acid derivatives are antibacterial agents effective against gram-positive and gram-negative bacterium.

Abstract: Biologically active sulfur analogs of 6-aminopenicillanic acid having a nucleophile substituted in the 6- position are made by reacting a sulfenyl chloride with esters of diazopenicillanic acid. Biologically active sulfur analogs of 7-aminocephalosporanic acid having a nucleophile substituted in the 7- position are analogously made by reacting a sulfenyl chloride with esters of 7-diazocephalosporanic acid. Deacetoxycephalosporins can be formed from the corresponding analog of 6-aminopenicillanic acid and derivations thereof, by sulfoxide rearrangement of the thiazolidine ring of penicillins to the dihydrothiazine ring of cephalosporins. These nucleophile substituted sulfur analogs of penicillins and cephalosporins are new antibacterial agents and display antibacterial activity against a variety of microorganisms.

Abstract: Biologically active sulfur analogs of 6-aminopenicillanic acid having a nucleophile substituted in the 6-position are made by reacting a sulfenyl chloride with esters of diazopenicillanic acid. Biologically active sulfur analogs of 7-aminocephalosporanic acid having a nucleophile substituted in the 7-position are analogously made by reacting a sulfenyl chloride with esters of 7-diazocephalosporanic acid. Deacetoxycephalosporins can be formed from the corresponding analog of 6-aminopenicillanic acid and derivations thereof, by sulfoxide rearrangement of the thiazolidine ring of penicillins to the dihydrothiazine ring of cephalosporins. These nucleophile substituted sulfur analogs of penicillins and cephalosporins are new antibacterial agents and display antibacterial activity against a variety of microorganisms.

Abstract: Sulfur analogs of 6-aminopenicillanic acid and biologically active derivatives thereof are formed in a photochemical reaction of the esters of 6-diazopenicillanic acid with thiol compounds. Sulfur analogs of 7-aminocephalosporanic acid and biologically active derivatives thereof may be analogously formed in a photochemical reaction of the esters of 7-diazocephalosporanic acid with thiol compounds, or preferably, are formed from the corresponding sulfur analogs of 6-aminopenicillanic acid and derivatives thereof, through sulfoxide rearrangement of the thiazolidine ring of penicillins to the dihydrothiazine ring system of cephalosporins. These sulfur analogs of penicillins and cephalosporins are new antibacterial agents and display antibacterial activity against a wide variety of organisms.