Synthetic and biosynthetic studies on vitamin B12.

Vitamin B12 is the anti-pernicious anemia vitamin. It functions as the main part of a coenzyme for a range of remarkable rearrangement reactions. The macrocycle for vitamin B12 is smaller by one carbon than that for chlorophyll and protoheme. Research is described involving numerous skills at the microscale level. In addition, synthesis of new pigments that have been encountered has been undertaken. A large part of the biosynthetic pathway to vitamin B12 has been revealed.