Three new diarylbutane lignans from the resin of Bursera fagaroides

Three new diarylbutane lignans, named 9-acetyl-9′-pentadecanoil-dihydroclusin (1), 2,3-demethoxy-secoisolintetralin monoacetate (4) and dihydroclusin monoacetate (5), have been isolated from the resin of Bursera fagaroides, together with two known ones, 2,3-demethoxy-secoisolintetralin diacetate (2) and dihydroclusin diacetate (3). The complete structure assignments were obtained by means of 1H and 13C NMR spectra.