Abstract: A compound of the formula (I): 1

Abstract: A compound of the formula: wherein R1 is amino or protected amino; R2 is hydrogen, lower alkyl or hydroxy protective group; R3 is carboxy or protected carboxy; R4 is an unsubstituted 5, 6 or 7-membered heteromonocyclic group containing two nitrogen atoms as heteroatoms, and which optionally further contains one oxygen or sulfur atom; or R4 is said 5, 6 or 7-membered heteromonocyclic group substituted by 1 to 4 groups selected from the group consisting of lower alkyl, lower alkoxy, lower alkylthio, lower alkylamino, cyclo(lower)alkyl, cyclo(lower)alkenyl, halogen, amino, protected amino, protected hydroxy, cyano, nitro, carboxy, hydroxy(lower)alkyl, amino(lower)alkyl, and carbamoyloxy; and n is 1 or 2.

Abstract: A novel crystal of 7&bgr;-[2-(2-aminothiazol-4-yl)-2-(Z)-(hydroxyimino)acetamido]-3-[pyrazol-4-yl)methylthio]3-cephem-4-carboxylic acid or a salt thereof.

Abstract: A novel crystal of 7&bgr;-[2-(2-aminothiazol-4-yl)-2-(Z)-(hydroxyimino)acetamido]-3-[pyrazol-4-yl)methylthio]3-cephem-4-carboxylic acid or a salt thereof.

Abstract: 1-Azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid compounds of the formula: ##STR1## in which R.sup.1 is carboxy, COO.sup.-- or protected carboxy,R.sup.2 is hydroxy(lower)alkyl or protected hydroxy(lower)alkyl,R.sup.8 is hydrogen or lower alkyl,Z is a group of the formula: ##STR2## wherein R.sup.3 is hydrogen; lower alkyl or lower alkenyl, each of which is optionally substituted by the group consisting of lower alkoxy, carbamoyl, hydroxy, halogen, mono(or di)(lower)alkylcarbamoyl, mono(or di)(lower)alkenylcarbamoyl, mono(or bis)[hydroxy(lower)alkyl]carbamoyl, optionally substituted cyclic-aminocarbonyl, acylamino, ureido, optionally substituted heterocyclic-carbonylamino, carbamoyloxy, mono(or di)(lower)alkylcarbamoyloxy, lower alkylthio, halo(lower)alkylthio, optionally substituted heterocyclicthio, optionally substituted heterocyclic group, optionally substituted aryl, and acyl;R.sup.9 is hydrogen or lower alkyl, andR.sup.

Abstract: Preparation of optically active 3-substituted azetidinones of the formula (I) ##STR1## in which R.sup.1 is a hydroxy-protective group wherein an allylic alcohol of the formula (II) ##STR2## is acylated, then subjected to asymmetric enzymatic hydrolysis yielding the R-allylic alcohol. The hydroxyl group is protected and then stereoselectively reacted with an amine which is subsequently cyclized to yield the desired 3-substituted azetidinone. Two new species of microorganisms have been isolated, Pimelobacter sp. No. 1254 and Bacillus megaterium No. 1253 which exhibit stereoselective esterase activity.

Abstract: 1-Azabicyclo[3.2.0]hept-2-ene-2-carboxyic acids having antimicrobial activity have been prepared.

Abstract: The invention relates to the preparation of 3,4-disubstituted-2-azetidinone compounds of the formula: ##STR1## in which R.sup.1 is hydrogen or amido-protective group, R.sup.2 is hydroxy(lower)alkyl or protected hydroxy(lower)alkyl, R.sup.3 is lower alkyl, and R.sup.4 is 1-(lower)alkyl-1-hydroxy(C.sub.2 -C.sub.6)alkyl, 1-(lower)alkyl-1-(protected hydroxy)-(C.sub.2 -C.sub.6)alkyl or 2-thioxothiazolidin-3-yl, useful as an intermediate for the production of antimicrobial agents by reacting a compound a compound of the formula: ##STR2## in which R.sup.5 is acyl, or salts thereof, with a compound of the formula:R.sup.3 --CH.sub.2 CO--R.sup.4or salts thereof, in the presence of an enolizating agent selected from the group consisting of stannous(lower)alkylsulfonate and stannous perhalo(lower)alkylsulfonate.

Abstract: The invention relates to crystalline 7-[2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-vinyl-3-cephem-4-car boxylic acid (syn isomer) useful as an antimicrobial agent.