A new cyclobutane lignan from Cinnamomum balansae

A new cyclobutane lignan, named cinbalansan (6), was isolated from the leaves of Cinnamomum balansae, along with five known compounds, 1,2-dimethoxy-4-(1-E-propenyl)benzene (1), 1,2-dimethoxy-4-(1-Z-propenyl)benzene (2), 1,2-dimethoxy-4-(2-propenyl)benzene (3), 3,4-dimethoxybenzaldehyde (4), and E-(3,4-dimethoxyphenyl)-2-propenal (5). The structure of cinbalansan was shown to be 1beta,2beta,3alpha,4alpha-1,2-dimethyl-3,4-bis(3,4-dimethoxyphenyl)cyclobutane by a combination of 1H-, 13C-NMR, and NOE- experiments and by direct analysis of the 1H-NMR spectrum by the method of X-application.