Diarylheptanoid and other phenolic constituents of Centrolobium species

Abstract

The heartwood of a specimen of Centrolobium tomentosum Benth (Leguminosae) has given (–)-centrolobine (1a), (–)-de-O-methylcentrolobine (1b), (–)-centrolobol (2), piceatannol (3)and the isoflavone formononetin (4). The heartwood of a second Centrolobium species, which could not be identified further at the U.S. Forest Products Laboratory, yielded (+)-centrolobine, (+)-de-O-methylcentrolobine, (+)-centrolobol, formononetin, 4',7-dihydroxyflavanone (5), 3-hydroxy-9-methoxypterocarpan (6) and minor amounts of a new dihydric phenol. This was identified by n.m.r. and X-ray diffraction measurements as 2-(2'-hydroxy-4'-methoxyphenyl)benzofuran-6-ol (8).