Vitamin corrin moiety

In most bio-bio examples two enzymes are applied but four examples already exist where eight enzymes operate in concert. Cascade record holder is a 12-slep synthesis of hydrogenobyrinic acid, the corrin moiety of vitamin B12, starting from 5-aminolevulinic acid [19], An example in which enzymes are switched on and off by pH variation is the four-step one-pot synthesis of ketoses from glycerol [20]. It may be noted that a modern laundry detergent formulation contains up to six different enzymes. 

On the other hand, Hisaeda and coworkers [504] found that the vitamin Bi2-mediated electroreductive optical resolution was accompanied by rearrangement Electroreduction of racemic 3-bromo-2-methoxy-2-phenylpropionate using a hydrophobic vitamin Bi2 mediator afforded ethyl (S)-2-methoxy-2-phenylpropionate in 55% ee, while a novel hydrophobic vitamin Bj2 modified by introducing a 1,3-phenylene diacetyl moiety into the peripheral site around the corrin s B ring, a so-called strapped hydrophobic vitamin B12, provided the corresponding R-enantiomer in 26% ee. 

Vitamin B12 contains cobalt in a corrin ring that resembles a porphyrin. In the cofactor forms of the vitamin, an adenosyl moiety or methyl group is attached to the cobalt, forming adenosylcobalamin or methylcobalamin (Figure 7-17). 

Chromate oxidation of acid hydrolysates of cyanocobalamin or direct oxidation of the vitamin with sodium chromate yielded three crystalline succinamide derivatives, particularly 3,3-dimethyl-2,5-dioxopyrrohdine-4-propionamide (VII). The isolation and identification of these compounds constituted proof for a 3,3-dimethylpyrrolidine-4-propionamide-like moiety (VIII) in the vitamin and was the first detailed degradative evidence for the pyrrole-like character of the corrin system of the vitamin. 

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