Sponge's molecular diversity through the ambivalent reactivity of 2-aminoimidazole: A universal chemical pathway to the oroidin-based pyrrole-imidazole alkaloids and their palau'amine congeners

The plausible biogenetic mechanism proposed in this communication clarifies the chemical pathway leading to over 60 polycyclic pyrrole-imidazole marin e alkaloids isolated from more than 20 different species of various genera (Agelas, Hymeniacidon, Axinella, Acanthella, Cymbastella, Phakellia...) of sponges. The tautomerism and ambivalent reactivity of 2-aminoimidazole prec ursors provide a consistent chemical pathway explaining the intriguing form ation of all the compounds of this class. The mechanistic proposal proposed here for the first time is unique in the sense that the chemical pathway i s universal and therefore provides fertile intellectual ground for the stud y of the enzymatic mechanism involved in this system.