A novel type of non-enzymatic reaction during the late steps in the biosynthesis of the angucycline antibiotics urdamycins C and D

Investigations on the late steps in the biosynthesis of the urdamycin complex showed the surprising result that the interconversion of urdamycin A (1) into the urdamycins C (2) and D (3) are due to non-enzymatic condensations of (1) with 4-hydroxyphenylpyruvic acid and indole-3-pyruvic acid, respectively.