New C-H Activation Reactions from Nature

Significance

Challis and co-workers present the first examples of oxidative cyclizations catalyzed by Rieske oxygenase-like enzymes. The enzymes McpG from Streptomyces longispororuber and RedG from S. coelicolor A3 were found to catalyze the regio- and stereodivergent oxidative cyclizations of undecylprodigiosin (4) to metacycloprodigiosin (5) and streptorubin (6), respectively. Feeding experiments with cultures of Streptomyces venezuelae expressing the enzymes of interest proved that the abovementioned enzymes are the only ones needed to catalyze the oxidative carbocyclizations. It was also shown that 2-undecylpyrrole (2) does not serve as a substrate proving that the formation of 4 from 2 and 1 precedes the C-H activation in the biosynthetic pathways of 5 and 6.