The isolation and synthesis of polyandrocarpamines A and B. Two new 2-aminoimidazolone compounds from the Fijian ascidian, Polyandrocarpa sp.

Chemical investigation of a Fijian ascidian, Polyandrocarpa sp., has resulted in the isolation of two new 2-aminoimidazolone-derived compounds, polyandrocarpamines A () and B (). The structures of these unique metabolites were determined by the interpretation of spectroscopic data and confirmed by total synthesis. The stereospecific synthesis of was accomplished using aldol condensation chemistry to generate an arylidene thiohydantoin that was subsequently transaminated to yield polyandrocarpamine A. Demethylation of synthetic afforded polyandrocarpamine B. Both the natural product and synthetic polyandrocarpamines were assigned Z geometries about the exocyclic double bond (C-5/C-7) on the basis of 13C/1H long-range coupling constants, which were measured using a gHSQMBC experiment.