The biosynthesis of pteridines. Part V. The synthesis of riboflavin from pteridine precursors

Abstract

The synthesis and reactions of various 8-substituted lumazine derivatives are described. In particular, it is shown that these compounds readily undergo hydration, and that the resulting carbinol-amines can take part in reactions which involve ring-opening in the pyrazine ring. These studies are extended to demonstrate a new chemical synthesis of riboflavin and related isoalloxazines from 8-substituted pteridine derivatives. A possible mechanism for this reaction, which is analogous to that involved in the biosynthesis of riboflavin, is discussed.Similar reactions of 2-iminopteridine derivatives are described.