Abstract: The present invention relates to a process for the preparation of a compound of general formula (I), ##STR1## wherein R.sup.1 represents a hydrogen atom or an alkyl group of 1-6 carbon atoms, and their salts, wherein the compound of formula (II): ##STR2## is reacted with a compound of formula (III): ##STR3## wherein R represents an alkyl group of 1-4 carbon atoms and R.sup.1 is the same as defined above, by heating their neutral pH mixtures at the boiling temperature of the mixture, and the resulting compound of general formula (IV): ##STR4## wherein R and R.sup.1 are the same as defined above, is cyclized into the compound of general formula (I) by further elevating the temperature of the neutral mixture, and if desired, the compounds of general formula (I) are transformed into their salts, or the compounds of general formula (I) are liberated from their salts.

Abstract: A process is disclosed for the preparation of a compound of the Formula (VI) ##STR1## wherein X is a hydrogen atom, or OH,Y is a hydrogen atom, OH or a methyl group,R.sup.2 is a CH--COOR group, or a group of the formula (XI) ##STR2## and R is a C.sub.1 to C.sub.2 alkyl group, which comprises the step of: reacting a condensed salt of the Formula (IV) ##STR3## wherein Me is Na.sup.+ or K.sup.+, with a reactive derivative of trifluoromethane-sulfonic acid of the Formula (V)F.sub.3 C--SO.sub.2 OH.The compounds of the Formula (VI) are intermediates in the preparation of penicillins and cephalosporins with antibiotic activity.