A. Marsili

Aliphatic and triterpenoid hydrocarbons from ferns

A detailed analysis of the hydrocarbon fractions from the extracts of 21 ferns belonging to 13 families was carried out. n-Alkanes from C24 to C35 and triterpenoid hydrocarbons of the hopane series were identified. The taxonomic value of these results is discussed.

A FLAVONOL GLYCOSIDE FROM AGRIMONIA EUPATORIA

Abstract A new flavonol glycoside, kaempferide 3-rhamnoside, was isolated from the aerial parts of Agrimonia eupatoria . The known compounds kaempferide, kae

The asymmetric bromination of alkenes in the presence of Cinchona alkaloids

Abstract The bromination of several acyclic and cyclic alkenes in the presence of Cinchona alkaloids produces optically active dibromides. The influence of the configuration of the alkaloid and of the structure of the alkene on the stereochemical results of the reaction has been investigated. The possible mechanism of the asymmetric bromination, and its use as a method for determining the absolute configuration of vicinal dibromides are discussed.

Triterpenes from thuidium tamariscifolium

Abstract Nine triterpenes and sterols have been isolated from Thuidium tamariscifolium . A number of aliphatic hydrocarbons and fatty acids were also detected.

Triterpenoid saponins and flavonoid glycosides from Bupleurum falcatum subsp. Cernuum

Abstract A new triterpenoid saponin, 16α,23,28,30-tetrahydroxyolean-11,13(18)-dien-3β-yl-glucopyranosyl-(1 → 3)-β- d -fucopyranoside, has been isolated from Bupleurum falcatum subsp. cernuum . Its structure was mainly elucidated by spectral analysis. Among known compounds, three other saponins and three flavonoid glycosides were also isolated from the plant.

Bromination of 3-cyclohexene-1-carboxylic acid, epoxydation of methyl 3-cyclohexene-1-carboxylate and opening of methyl cis- and trans-3,4-epoxycyclohexane-1-carboxylate:Stereochemical results

Abstract Bromination of 3-cyclohexene-1-carboxylic acid ( 1 ) gives mixtures of the trans -dibromo-derivatives 3 and 4 and cis -3-hydroxy- trans -bromocyclohexane-1-carboxylic acid lactone ( 5 ). Lactone 5 is obtained by brominating 1 in the presence of triethylamine, showing that halogen preferentially attacks the double bond anti with respect to the carboxyl group. Epoxydation of the methyl ester of 1 also takes place prevalently anti to the methoxycarbonyl group. Ring opening of methyl cis -3,4-epoxycyclohexane-1-carboxylate ( 7 ) with hydrogen bromide gives methyl trans -3-bromo- cis -4-hydroxy- ( 13 ) and cis -3-hydroxy- trans -bromocyclohexane-1-carboxylate ( 6 ). Similar opening of methyl trans -3,4-epoxycyclohexane-1-carboxylate ( 11 ) affords methyl trans -3-hydroxy- cis -4-bromocyclohexane-1-carboxylate ( 14 ). The steric course of these reactions is ascribed to the effect of the electron-withdrawing substituent.

21-Hopene and some other constituents of Pseudoscleropodium purum

Abstract 21-Hopene, 22(29)-hopene and ursolic acid were isolated from a moss. Cyclolaudenol, 31-norcyclolaudenol, three sterols and a number of aliphatic hydrocarbons and fatty acids were also detected.

Structure and stereochemistry of a triterpenoid epoxide from Adiantum capillus-veneris

Abstract A triterpenoid epoxide obtained from Adiantum capillus-veneris has been identified as 3α,4α-epoxyfilicane on the basis of several chemical and physical observations.

Boron trifluoride-catalyzed rearrangements of some tetrasubstituted neotriterpene epoxides—II: Hopene-II oxide and its analogue in the A:B-neoallobetulin series

Abstract While hopene-II oxide is converted by HCl into the 11,13(18)-diene, it rearranges quantitatively under the action of BF3-ether complex to the 19(18 → 13)-abeo-18-oxo derivative. The structurally similar 9,10β:19β, 28-diepoxy-A:B-neo-18β-oleanane, prepared from allobetulin, behaves in an entirely analogous manner.

Boron trifluoride-catalysed rearrangements of some tetrasubstituted neotriterpene epoxides—I

Abstract The treatment of A′-neogammacer-17(21)-ene oxide ( 1a ) with BF 3 ·Et 2 O complex in CHCl 3 produces entirely different results from those obtained when the same epoxide is treated with HCl in EtOH: while the protic acid converts the compound into the 15,17(21)-diene ( 2a ), the Lewis acid produces rearrangements in the carbon skeleton, with formation of the 28-nor-21α-methyl-12,17-diene ( 3a ) and of the 22,29,30-trisnor-17α-isopropyl-21-one ( 4a ). The structurally similar 19β,28-epoxy-A-neo-18α-olean-3(5)-ene oxide ( 1b ) behaves in a completely analogous manner.