Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... Through a general synthetic scheme, hymenidin, oroidin and keramadine, all marine 2-aminoimidazole metabolites were prepared. Seven steps from imidazolemethanol provided an improved synthesis of oroidin and the first synthesis of hymenidin and keramadine.