Vitamin B12 is required by mammals but it is only made by bacteria, hence it is a vitamin that is mandated in the human diet. Its structure, first solved by Dorothy Hodgkin's group using X-ray crystallography, was for a long time the most complex non-repetitive natural product known. The total syntheses of vitamin B12 by the groups of Woodward and of Eschenmoser were regarded as the pinnacle of achievement in organic synthesis, and elucidation of the biosynthesis of the vitamin was also a tremendous challenge. This chapter gives an account of the current knowledge of the biosynthesis as well as some of the historical background of the field.
Department of Chemistry
University of Cambridge