Resveratrol tetramers with a C6-C3 or a C1, unit from upuna borneensis

Investigation of the chemical constituents in the stem of Upuna borneensis (Dipterocarpaceae) resulted in the isolation of three new resveratrol derivatives, upunaphenols L (1), M (2) (resveratrol tetramers with a C-6-C-3 unit) and N (3) (resveratrol tetramer with a C, unit). The structures have the same partial structure as vaticanol B (4). Upunaphenols L and M are new complex polyphenol compounds, lignostilbene. Their structures were determined by spectroscopic analysis including two dimensional NMR. Upunaphenol M was found to be an artifact generated by silica gel catalyzed methanolysis of 1.