Neolignans and a lignan from Piper clarkii

Abstract Four new compounds, a lignan and three neolignans, together with one known neolignan have been isolated from the leaves and stems of Piper clarkii . Their structures were established on the basis of 1 H, 13 C and 1 H 1 H COSY NMR, NOE and mass spectral data and CD curves. The novel lignan was identified as (2 S ,5 S )-diveratryl-(3 R ,4 S )-dimethyltetrahdrofuran. The structures of the new neolignans were established as (7 R ,8 R ,1′ S )- Δ 8′ -1′-methoxy-3,4-methylenedioxy-1′,6′-dihydro-6′-oxo-7.0.4′,8.3′-lignan[2 R ,3 R ,5 S )-2-(1,3-benzodioxol-5-yl)-3,5-dihydro-5-methoxy-3-methyl-5-(2-propenyl)-6(2H)-benzofuranone], (7 S ,8 S ,3′ R )- Δ 8′ -3,3′,4-trimethoxy-3′,6′-dihydro-6′-oxo-7.0.4′,8.3′-lignan[2 S ,3 S ,3 aR )-2-(3,4-dimethoxyphenyl)-3,3a-dihydro-3a-methoxy-3-methyl-5-(2-propenyl)-6(2H)-benzo-furanone] and rel-(7 S ,8 S ,1′ R ,3′ R )- Δ 8′ -5′-methoxy-3,4-methylenedioxy-1′,2′,3′,4′-tetrahydro-2′,4′-dioxo-7.3′,8.1′- lignan[(7 S ,6 S ,5 R ,1 R )-7-(1,3-benzodioxol-5-yl)-3-methoxy-6-methyl-5-(2-propenyl)bicyclo[3.2.1]oct-3-ene-2,8-dione]. The known neolignan has been identified as denudatin B.