Synthesis and Investigation of the Abiotic Formation of Pyonitrins A-D.

Pyonitrins A-D are recently isolated natural products from the insect-associated Pseudomonas protegens strain, which were isolated from complex fractions that exhibited antifungal activity via an in vivo murine candidiasis assay. Genomic studies of Pseudomonas protegens suggested that pyonitrins A-D are formed via a spontaneous nonenzymatic reaction between biosynthetic intermediates of two well-known natural products pyochelin and pyrrolnitrin. Herein we have accomplished the first biomimetic total synthesis of pyonitrins A-D in three steps and studied the nonenzymatic formation of the pyonitrins using N-15 NMR spectroscopy.