Epimerization of cyanocobalamin. Improved synthesis of cyano-8-epicobalamin and its characterization by x-ray crystallography, and 1H, 13C, and 15N NMR

Probing the nature of the Co(III) ion in cobalamins: The reactions of aquacobalamin (vitamin B12a), aqua-10-chlorocobalamin and aqua-10-bromocobalamin with anionic and neutral ligands

“…The 1 H and 13 C NMR spectra of [H 2 O-(10-Br)Cbl] + were assigned using the methodology developed by Brown [40][41][42][43][44]. The full assignments are given in Tables S3 and S4 of the Supplementary material, and a brief account of the methodology used is given there as well.…”

Synthetic Approaches toward Vitamin B12 Conjugates

“…A selective method exists only for the synthesis of c ‐carboxylic acid 13 d (Scheme ). It can be synthesized via stepwise formation of (CN)Cbl ‐c ‐lactone 14 (after treatment of (CN)Cbl ( 1 a ) with chloramine‐T in aqueous acidic media, with NaOH in H 2 O at 100 °C or with NCS/NBS/AcOH at room temperature) followed by reduction with either a) NaBH 4 , that also furnishes epimeric product 13 e or with b) zinc in aqueous ammonium chloride solution selectively giving acid 13 d (Scheme ) …”

Vitamin B12: chemical modifications

“…The epimerized compound was subsequently coupled with NH 4 Cl giving (CN)-8-epi-Cbl 14 in 80% yield. 27 3.3 Reactions at R5 0 -OH Toraya et al was the first to report the selective modification at the 5 0 -OH position by reacting (CN)Cbl 1 with succinic anhydride in the presence of pyridine giving a mixture of two compounds (Scheme 12). 28 The major product was the desired 5 0 -monosuccinyl-(CN)Cbl 50 (90% yield) while the minor one was the 2 0 ,5 0 -disuccinyl-(CN)Cbl derivative.…”