A new 6,9′-cyclolignan from Syringa pinnatifolia

A new lignan, 4,4′-dihydroxy-3,3′-dimethoxy-6,9′-cycloligna-7,8′-dien-9′-al, was isolated from the stem of Syringa pinnatifolia Hems1. var. alashanensis MA. et S.Q. Zhou (S. pinnatifolia). This is the first report on the structure elucidation of a new compound based on spectroscopic methods including UV, IR, ESI-MS, 1D NMR and 2D NMR techniques.