Dendrobium Alkaloids

spectrum of the orchid alkaloid dendrocrepine (12) shows that the phenyl groups give rise to six resonances, and the non-equivalence of the two ortho and meta positions is considered to be caused by steric inhibition of rotation of the phenyl groups. Similar steric inhibition of the free rotation of the phenyl group in 2,3-dimethyl-l-phenylcyclohexanol was demonstrated, and in the spectrum of dendrocrepine the six phenyl resonances were reduced to four at -1-57 C. 

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In the spectra of [200] and [201] (synthetic intermediates in the synthesis of Dendrobium alkaloids) the shifts of the 2-protons are... 

Dendrobium Alkaloids.—A third synthesis of shihunine, the principal base of several Dendrobium spp., has been reported. It involves allowing the dilithio-anion (12) to react with l-methyl-2-pyrrolidone (13), to yield ( )-shihunine (14) in 23% yield.11 Full experimental details pertaining to a synthesis of ( )-dendrobine, reported briefly earlier, have been described.12... 

Dendrobium Alkaloids.—Investigations on the biosynthesis of shihunine (9) have been published in full11 (see Chapter 1). Full details of the synthesis of 8-epiden-drobine, reported briefly earlier, have been published.12... 

Dendrobium Alkaloids. —An earlier reported synthetic route to (+)-dendrobine has been improved by the development of a superior synthesis of the perhydroindenone intermediate that is involved.13... 

Dendrobium Alkaloids.—8-Epidendrobine (14) has been synthesized employing a route involving a diene isomerization in a Diels-Alder reaction (Scheme 3). To account for the unexpected stereochemical result of the latter addition [(12)->(13) and epimeride] it is proposed that ester (15) assumes a very hindered conformation in the transition state, involving no secondary orbital overlap between diene and ester groups. However isomerization of the trisubstituted double bond to give (16) leads... 

Dendrobium Alkaloids.—A possible synthetic route to the alkaloid dendrobine (6 R = H) has been explored. The key reaction in the sequence was the intramolecular... 

Dendrobium Alkaloids.—Recent structural elucidation work on Dendrobium alkaloids by the Liining group has been sunmiarized. New alkaloids crepid-amine (44a) and dendrocrepine (44b) related to crepidine (see Vol. 3 of these Reports) have been obtained from D. crepidatwn. The structure of dendrocrepine (44b) has been established by X-ray crystallographic analysis of its hydrobromide. ... 

Dendrobium Alkaloids.—A new total synthesis of ( )-dendrobine (8) has been described, by a highly stereoselective route using an intramolecular Diels-Alder reaction with the triene (9). ... 

Dendrobium alkaloids. Alkaloids occurring in the orchid genus Dendrobium. Similar to the Nuphar alkaloids, these are pseudoalkaloids whose C-skeletons originate from terpene metabolism (sesquiterpenes). About 15 alkaloids are known, they were first isolated from Dendrobium nobile and later also from other species a typical representative is denr/w/nne C,6H25N02, Mr 263.38, mp. 134-136°C, [a]i -48.4° (CHjOH). ... 

Medical Uses of Monoterpenoid Alkaloids Sesquiterpenoid Alkaloids Dendrobium Alkaloids Nuphar and Castor Alkaloids Alkaloids of the Celastraceae and Hippocrateaceae Khat... 

Dendrobium alkaloids a group of terpene alkaloids from various species in the orchid genus Dendrobium. The D. are sesquiterpenes with one heterocyclic nitrogen atom. 

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