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Abstract

A process for the preparation of a 7-acylamino-3-hydroxy-2-cephem-4-carboxylic acid, 7-acylamino-3-hydroxy-1-dethia-1-oxa-3-cephem-4-carboxylic acid or derivative thereof of the general formula ##STR1## in which R.sup.1 is hydrogen or optionally substituted alkyl, alkenyl, alkinyl, aralkyl, aryl, heteroaryl, heteroaralkyl, aryloxyalkyl, heteroaryloxyalkyl, alkoxyalkyl, arylthioalkyl, heteroarylthioalkyl, alkylthioalkyl, alkoxy, aryloxy, alkylthio or arylthio, R.sup.2 is hydrogen, a carboxy-protective group or a pharmaceutically useful ester radical, and X is sulphur or oxygen, which comprises: (a) reacting a compound of the formula ##STR2## with (i) a compound of the formula ##STR3## in which R.sup.2 and X have the abovementioned meaning and Y represents diazo (N.sub.2) or hydrogen (H.sub.2) in an inert solvent in the presence of a Lewis acid or proton acid catalyst, or (ii) a compound of the formula HX--CH.sub.2 --C.tbd.C--COOR.sup.2 to form an intemediate compound having a triple bond, and hydrating the triple bond, the compounds thus obtained, for Y being hydrogen (H.sub.2)--(in case of Y=diazo (N.sub.2) directly the compounds of general formula (2) are obtained) thereby to produce a compound of the formula ##STR4## (b) reacting such compound with an azide in a solvent in the presence of a base to give a compound of the formula ##STR5## (c) converting said compound to the desired product by (i) irradiation in an inert solvent, or (ii) warming in the presence of a catalyst. The end products are, or can be converted to, known .beta.-lactam antibiotics.

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