Process for preparing .beta.-lactam derivatives

A process for preparing an allenyl .beta.-lactam compound represented by the formula (4), characterized by reacting the hydroxyl group of a .beta.-lactam compound represented by the formula (1) with a reactive functional group derivative of sulfonic acid represented by the formula (2) to convert the compound of the formula (1) to a .beta.-lactam compound represented by the formula (3), thereafter reacting the resulting .beta.-lactam compound represented by the formula (3) with a tertiary organic base to convert the compound of the formula (3) to the allenyl .beta.-lactam compound of the formula (4), thereafter causing an acidic cation exchange resin and a basic anion exchange resin, to alternately or simultaneously act on the .beta.-lactam compound of the formula (4) and isolating the allenyl .beta.-lactam compound of the formula (4) from the resulting reaction solution ##STR16## wherein R.sup.1 is a hydrogen atom, amino or protected amino, R.sup.2 is a hydrogen atom, halogen atom, lower alkoxyl, formyl, acetyl, propionyl, butyryl, isobutyryl, or lower alkyl having hydroxyl or protected hydroxyl as a substituent, R.sup.3 is a hydrogen atom or carboxylic protecting group, R.sup.4 is an aromatic group which may have a substituent, or a nitrogen-containing aromatic heterocyclic group which may have a substituent, wherein said substituent is selected from the group consisting of halogen atoms, straight-chain or branched C.sub.1-4 alkoxyl group, straight-chain or branched C.sub.1-4 alkylthio groups, straight-chain or branched C.sub.1-4 alkylsulfonyloxy groups, aromatic sulfonyloxy or methyl-substituted aromatic sulfonyloxy, straight-chain or branched C.sub.1-4 alkyl groups, amino, amino which has as a substituent one or two straight-chain or branched C.sub.1-4 alkyl groups, hydroxyl, acyloxy group represented by R'COO-- wherein R' is phenyl, tolyl, or straight-chain or branched C.sub.1-4 alkyl group, acyl group represented by R'CO-- wherein R' is as defined above, nitro, cyano, and phenyl, and n is 0 to 2

• R.sup.5 --SO.sub.2 --X (2)
• wherein R.sup.5 is an aliphatic, alicyclic or aromatic hydrocarbon group which may have a substituent, wherein said substituent is selected from the group consisting of halogen atoms, straight-chain or branched C.sub.1-4 alkoxyl group, straight-chain or branched C.sub.1-4 alkylthio groups, straight-chain or branched C.sub.1-4 alkyl groups, amino, amino which has as a substituent one or two straight-chain or branched C.sub.1-4 alkyl groups, hydroxyl, acyloxy group represented by R'COO-- wherein R' is phenyl, tolyl, or straight-chain or branched C.sub.1-4 alkyl group, acyl group represented by R'CO-- wherein R' is as defined above, nitro, cyano, and phenyl, and X is a halogen atom or an OSO.sub.2 R.sup.5 group ##STR17## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and n are as defined above ##STR18## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and n are as defined above.