Pub No:
Cobalamin Models
Xie, L.Y., Roussi, P.F., and David Dolphin
Inorganic Reactions and Methods, J.J. Zuckerman, Ed., Verlag Chemie, Weinheim
Vol. 16, 408-414
Coenzyme B12, methylcobalamin (Fig. Ia and b) and closely related derivatives were the first organometallic compounds to be found in nature. Their complex structures, together with that of vitamin B12 (Fig. lc), were elucidated by X-ray crystallography. After isolation of the B12 coenzyme it was realized that the cobalt-carbon (CoŚC) bond could be stabilized by other ligands. Many organocobalt compounds were subse- quently synthesized and used as models for the alkylcobalamins. The most commonly used are cobaloximes and Costa complexes. The skeleton of vitamin B12 (i.e., the porphyrin nucleus minus C-20) is called corrin. The compound containing the corrin nucleus is called a corrinoid. The compound containing the cobalt atom and the standard side chains in the free acid form is called cobyrinic acid, but cobyric acid when the side chains are at positions a, b, c, d, e, g, are in the amide form. Cobyrinic acid substituted with D-l-amino-2-propanol at position f is called cobinic acid. The substituted cobyric acid is called cobinamide. Cobinic acid substituted with D ribofuranose-3- phosphate at position 2 of the aminopropanol is called cobamic acid; the substituted cobinamide is called cobamide. Many B12 vitamins and derivatives in which the heterocyclic base is 5,6- dimethylbenzimidazole are given the trivial name cobalamin; see D. Dolphin, ed., B12, Wiley- Interscience, New York, 1982.

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