Synthesis of Cycloprodigiosin Identifies the Natural Isolate as a Scalemic Mixture
Rebecca E Johnson1, Tristan de Rond1, Vincent N G Lindsay1
1†Department of Chemistry, University of California, Berkeley, California 94720, United States.
Organic Letters
|June 27, 2015
Abstract:
The enantiomers of the natural product cycloprodigiosin were prepared using an expedient five-step synthetic sequence that takes advantage of a Schöllkopf-Barton-Zard (SBZ) pyrrole annulation with a chiral isocyanoacetate and a nitrocyclohexene derivative. Using chiral HPLC and X-ray crystallographic analyses of the synthetically prepared material and natural isolate (isolated from the marine bacterium Pseudoalteromonas rubra), naturally occurring cycloprodigiosin was determined to be a scalemic mixture occurring in an enantiomeric ratio of 83:17 (R)/(S) at C4'.

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