American Chemical Society, Journal of Organic Chemistry, 10(75), p. 3240-3250, 2010
DOI: 10.1021/jo1002054
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Cultivation of actinomycete strain CNQ-418, retrieved from a deep ocean sediment sample off the coast of La Jolla, California, has provided marinopyrroles A–F. Sharing just 98% 16S rRNA gene sequence identity with S. sannurensis, the strain likely represents a new Streptomyces species. The metabolites contain an unusual 1,3′-bipyrrole core decorated with several chlorine and bromine substituents and possess marked antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The congested N,C-biaryl bond establishes an axis of chirality that, for marinopyrroles A-E, is configurationally stable at room temperature. Moreover, the natural products are fashioned strictly in the M-configuration. The Paal-Knorr condensation was adapted for the synthesis of the 1,3′-bipyrrole core. Halogenation of this material with N-bromosuccinimide cleanly furnished the 4,4′,5,5′-tetrahalogenated core that characterizes this class of marine-derived metabolites.