Lignans and neolignans from stems of Piper wightii

摘要: Abstract Studies of the petroleum ether extract stems Piper wightii Miq. resulted in isolation three novel 2′-oxo-8.1′- and 4′-oxo-8.5′-neolignan with unusual structures, namely 4′,5′-dimethoxy-3,4-methylenedioxy-2′-oxo-Δ 3′,5′,8′ -8.1′-lignan (6-[2-(1,3-benzodioxol-5-yl)-1-methylethyl]-3,4-dimethoxy-6-(2-propenyl)-2,4-cyclohexadien-1-one) ( 1 ), iso -4′,5′-dimethoxy-3,4-methylenedioxy-2′-oxo-Δ -6-[2-(1,3-benzodioxol-5-yl)-1-methylethyl]-3,4-dimethoxy-6-(2-propenyl)-2,4-cyclohexadien-1-one) 2 ) 1′,2′-dimethoxy-3,4-methylenedioxy-4′-oxo-Δ -8.5′-lignan (2-[2-(1,3-benzodioxol-5-yl)-1-methylethyl]-4,5-dimethoxy-4-(2-propenyl)-2,5-cyclohexadien-1-one)( 3 together one tetrahydrofuran lignan, rel-(7 S ,8 ,7′ ,8′ )-3′,4′-dimethoxy-3,4-methylenedioxy-8.8′,7.O.7′-lignan (2 ,3 ,4 ,5 )-5-[5-(3,4-dimethoxyphenyl)-3,4-dimethyl-2-tetrahydrofuranyl]-1,3-benzodioxol) 4 ). The structures were elucidated on basis spectropic data H-, 2D- 13 C NMR, NOE, UV, IR MS). Additionally,two known neolignans, R ,3′ ,1′ )-3′,4′-dimethoxy-3,4-methylenedioxy-6′-oxo-Δ 4′,8′ -8.3′,7.O.2′-lignan (fargesone A, 5 B, 6 isolated for fist time from P. .