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

Abstract

Chem. investigation of a Fijian ascidian, Polyandrocarpa sp., has resulted in the isolation of two new 2-aminoimidazolone-derived compds., polyandrocarpamines A (I) and B (II). The structures of these unique metabolites were detd. by the interpretation of spectroscopic data and confirmed by total synthesis. The stereospecific synthesis of I was accomplished using aldol condensation chem. to generate an arylidene thiohydantoin that was subsequently transaminated to yield polyandrocarpamine A. Demethylation of synthetic I 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 consts., which were measured using a gHSQMBC expt.