Specific enzyme inhibitors in vitamin biosynthesis. Part II. Revised structures for some 8-substituted pyrido[2,3-d]pyrimidines

Abstract

The structures assigned to some 8-substituted pyrido[2,3-d]pyrimidines in an earlier paper have been re-examined. These compounds were synthesised as potential competitive inhibitors of the enzyme riboflavin synthetase. Data from enzyme inhibition studies suggested that the original structures had been wrongly assigned. This was confirmed by studies of nuclear Overhauser effects and by photochemical degradation of the compounds.