A kinetic study on the alkaline hydrolysis of cephaloridine (1) at pH
10.5 and 37-degrees was carried out using ion-pair reversed-phase HPLC
. The main resulting degradation products, the 7-epimer 2 of 1, the DE
LTA2-isomer 3 of 1, and the 3-methylidene compound 4 were identified.
The presence of a pyridinio group at C(3(1)) results in a slightly inc
reased formation constant for the 3-methylidene compound 4 and the 7-e
pimer 2, and introduces a new reaction: the isomerization of the doubl
e bond at C(3) in the dihydrothiazine ring to C(2).