Plagiochilines T and U, 2,3-secoaromadendranes from the liverwort Plagiochila carringtonii from Scotland

NMR fingerprinting of five samples of Plagiochila carringtonii has shown th at the species in Scotland is characterized by the presence of plagiochilin es T and U, two new 2,3-secoaromadendranes, in the ratio 2:1, respectively. Plagiochilines T and U were isolated, characterized by GC-MS and H-1 NMR a nd the structures elucidated as 2 alpha,15-diacetoxy-2,3-epoxy-2, 3-seco(1 alpha,5 alpha,6 beta,7 beta)-aromadendra-3, 10(14)-dien-13-al and methyl 2 alpha: 15-diacetoxy-2,3-epoxy-2,3-seco-( 1 alpha, 5 alpha,6 beta, 7 beta)-a romadendra-3,10(14)-dien-13-oate, respectively. They differ from plagiochil ine C by oxidation of the cyclopropyl beta-methyl substituent to an aldehyd e and a methyl ester respectively and are the first recorded examples with oxidation beyond the alcohol level at this position. P. carringtonii may be assigned to the most common Plagiachila chemotype, the 2,3-secoaromadendra ne group. (C) 1999 Elsevier Science Ltd. All rights reserved.