NOVEL MARINE SPONGE ALKALOIDS .2. STRUCTURES AND TOTAL SYNTHESIS OF 2-AMINOIMIDAZOLES FROM A NOTODORIS NUDIBRANCH

The anthelmintic active crude extract of an Indo-Pacific nudibranch has yielded dorimidazole A [1], 1-methyl-2-amino-4(p-hydroxybenzyl)i?? midazole, accompanied by the known compound isonaamine A [2], 2-amino-1,4-di(p-hydroxybenzyl)imidazole. These overall structures were established with the aid of spectral data. The regiochemistry within the imidazole ring was deduced by employing C-13-nmr chemical shift increment values. The structure of 1 was confirmed by a four-step total synthesis, in 21% overall yield. New insights on the biogenesis of sponge-derived amino imidazoles are provided by the structure of 1.