Dibenzylbutyrolactone and dibenzylbutanediol lignans from Peperomia duclouxii

Nine new lignans (1-9), including five dibenzylbutyrolactones and four dibenzylbutanediols, were obtained from an ethyl acetate extract of the whole plants of Peperomia duclouxii. The structures of 1-9 were determined by spectroscopic methods (mainly extensive 1D and 2D NMR experiments and by mass spectral measurements). The absolute structures were elucidated as 2S,3S from their optical rotations and by chemical transformations.