Structures of three new 2-arylbenzofuran derivatives from the chinese crude drug "Sang-Bai-Pi" (morus root bark).

Abstract

Three new 2-arylbenzofuran derivatives named mulberrofurans K, N, and O were isolated from the extract of the Chinese crude drug "Sang-Bai-Pi" (Japanese name "Sohakuhi"), the root bark of Morus sp. (Moraceae). The structures of mulberrofurans K, N and O were shown to be 1, 2, and 3, respectively, on the basis of spectral and chemical evidence. Mulberrofurans K and O are optically active and may be regarded biogenetically as Diels-Alder type adducts of chalcone derivatives and a dehydroprenyl-2-arylbenzofuran derivative. Furthermore, mulberrofuran K seems to be derived from the Diels-Alder type adduct by intramolecular ketalization.