Two new monoterpene aldehydess3-formyl-2,2,6-trimethyl-3,5-cyclohexadienyl angelate (3) and 3-formyl-2,2,4-trimethyl-3,5-cyclohexadienyl angelate (4)swere identified from the hexane extract of Bupleurum gibraltaricum. Their structures were elucidated by spectroscopic analysis.As a part of our research on medicinal and aromatic plants of southern Spain and northern Morocco, we carried out a study of Bupleurum gibraltaricum Lam. (Umbelliferae), a species whose distribution is restricted to these countries, 1,2 where it is used in folk medicine. 3 Its essential oil has been demonstrated to have marked antiinflamatory activity. [4][5][6] In a previous paper about the phytochemistry of this plant, the isolation of the monoterpene aldehydes 1 and 2 was reported. 7 This paper describes the identification of two new natural products (3 and 4) from its hexane extract.
Results and DiscussionIn the hexane extract of the leaves of B. gibraltaricum Lam. the following well-known aromatic compounds and terpenoids were identified: d
R e p le 27 juillet 1993 TAHAR LAKHLIFI, AHMED SEDQUI, TOUFIK FATHI, BERNARD LAUDE et JEAN-FRAN~OIS ROBERT. Can. J. Chem. 72,1417 (1994. La synthkse de sept 5-ph~nyl-3,4-dihydro-2H-pyrrole-2-carboxylates de mCthyle precurseurs d'ylures d'azomCthine cycliques pentagonaux 1 est dkcrite. Ces produits i caractere dipolaire rkagissent avec les N-methyl et N-phCnylmal6imides de fa~on diastCrCospCcifique. L'approche des reactants se fait sur la face la moins encombrke du dip81e-1,3 et en endo pour donner le cycloadduit thermodynamiquement le plus stable de structure exo. De plus, l'oxydation de ces composes 1 permet d'acceder aux pyrroles substituCs correspondants.TAHAR LAKHI~FI, AHMED SEDQUI, T o m FATHI, BERNARD LAUDE, and JEAN-FRAN~OIS ROBERT. Can. J. Chem. 72, 1417Chem. 72, (1994. Seven derivatives of methyl 5-phenyl-3,4-dihydro-2H-pyrrole-2-carboxylates 1 were synthetized. These compounds are precursors of pentagonal cyclic azomethine ylids, the two sides of which are diastereotopic. The 1,3-dipolar species react with N-methyl and N-phenylmaleimides diastereospecifically. The approach of the reactant species occurs from the less hindered side of the 1,3-dipole and in endo to lead the thermodynamically stable exo cycloadduct. Moreover, oxidation of the compounds 1 gives the corresponding substituted pyrroles.
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