Synthesis of Cycloprodigiosin Identifies the Natural Isolate as a Scalemic Mixture
摘要:
The enantiomers of the natural product cycloprodigiosin were prepared using an expedient five-step synthetic sequence that takes advantage of a Schollkopf-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 cyclo-prodigiosin was determined to be a scalemic mixture occurring in an enantiomeric ratio of 83:17 (R)/(S) at C4'.