Direct Biochemical Nitration in the Biosynthesis of Dioxapyrrolomycin. A Unique Mechanism for the Introduction of Nitro Groups in Microbial Products.

The nitro group of dioxapyrrolomycin (1) was shown to be introduced via direct biochemical nitration in cultures of the producing organism Streptomyces fumanus containing K15N18O3 as the sole source of nitrogen; the nitro group of dioxapyrrolomycin produced under these conditions contained the same ratio of 18O to 15N as was present in the labelled nitrate precursor, the extent of 18O enrichment of the nitro group being determined by negative electron impact mass spectrometry and 15N n.m.r. spectroscopy.