5-Methoxypropacin, a novel coumarinolignoid from Protium unifoliolatum.

The novel coumarinolignoid 5-methoxypropacin was isolated from the ethereal extract of the wood of the Amazonian species Protium unifoliolatum. Its structure was elucidated by spectroscopic methods as IR, 1D and 2D (1)H, (13)C-NMR and mass spectrometry. The regioisomer and the position of coumarin and arylpropanoid coupling were determined by long-distance C-H correlation (HMBC) and NOE experiments. Scopoletin and beta-sitosterol were also isolated and identified by the same physical methods.