Process for preparing cephem derivatives

A process for preparing a cephem compound of the formula ##STR20## wherein R.sup.1 is amino or protected amino;

• R.sup.2 is hydrogen or lower alkoxyl;
• R.sup.3 is hydrogen or a carboxylic acid protecting group;
• and Y is halogen, hydroxyl, azido, cyano or isocyano;
• or --OR.sup.7, --OCOR.sup.7, --SCSOR.sup.7, --SCSN(R.sup.7).sub.2, --NHR.sup.7, --N(R.sup.7).sub.2 or --SO.sub.2 R.sup.7, wherein R.sup.7 is lower alkyl, phenyl or naphthyl;
• or --SR.sup.8, wherein R.sup.8 is lower alkyl, phenyl, naphthyl, piperidino, morpholino, 1-piperazinyl, 1-pyrrolidinyl, 1-imidazolidinyl, 1-pyrazolidinyl, 2-pyrrolin-1-yl, 2-imidazolin-1-yl, 3-pyrazolin-1-yl, 1-indolinyl, 2-indolinyl, 1-pyrrolyl, 1-indolyl, 2-isoindolyl, 1-imidazolyl, 1-pyrazolyl, 1-benzimidazolyl, 1H-1-indazolyl, 1-triazolyl or 1-tetrazolyl;
• optionally substituted by halogen, hydroxyl, nitro, cyano, aryl, lower alkyl, amino, mono lower alkylamio, di lower alkylamino, mercapto, lower alkyl alkylthio, arylthio, formyl or formyloxy;
• R.sup.6 COO--, R.sup.6 CO--, R.sup.6 O-- or R.sup.6 OCO--, wherein R.sup.6 is lower alkyl phenyl or naphthyl, which comprises reacting an allenyl .beta.-lactam of the formula ##STR21## wherein R.sup.1, R.sup.2 and R.sup.3 are as defined above;
• and X is --SO.sub.2 R.sup.4 or --SR.sup.4, wherein R.sup.4 represents phenyl, naphthyl, thiazol-2-yl, thiadiazol-2-yl, benzothiazol-2-yl, oxazol-2-yl, benzoxazol-2-yl, imidazol-2-yl, benzoimidazol-2-yl, pyrimidinyl or pyridyl, optionally substituted by halogen, hydroxyl, nitro, cyano, aryl, lower alkyl, amino, mono lower alkylamio, di lower alkylamino, mercapto, lower alkyl alkylthio, arylthio, formyl or formyloxy;
• or R.sup.6 COO--, R.sup.6 CO--, R.sup.6 O-- or R.sup.6 OCO--, wherein R.sup.6 is lower alkyl, phenyl or naphthyl;
• with H--Y.