Intermediates represented by the following formulas are useful for synthesizing 3-hydroxy-3-cephem compounds ##STR1## wherein A and B each is a hydrogen or amino substituent; R is a hydrogen or thiol substituent; Hal is a halogen; X is a hydroxy or carboxy protecting group; the broken line between A and R shows that when R and B are hydrogens, and A is a carboxylic acyl, the substituents can be combined to form an azetidinothiazoline bicyclic ring; and the enamine derivatives thereof. One embodiment provides for cyclizing a compound of the formula: ##STR2## wherein A, B, X and Hal are as defined above, which comprises treating the said compound with an acid, base, or solvent if required in the presence of a catalyzer to give a compound represented by following formula ##STR3## In a further embodiment a compound represented by the following formula ##STR4## wherein A, B, R and X are as defined above, is prepared by a process which comprises treating an enamine of a compound represented by following formula ##STR5## wherein A, B, R, X, Hal and broken line are as defined above, with a disubstituted amino containing from 2 to 20 carbon atoms, with the action of an aqueous acid.