Dendrobines

The trimer famesyl pyrophosphate (35), in addition to serving as a pregenitor of steroids via squalene (114), is also the pregenitor of the compounds known as sesquiterpenes. It has been suggested that famesyl pyrophosphate (88) similarly serves as the carbon backbone of alkaloids such as deoxynuphatidine (120) ftom Nupharjapomcum (Nymphaceae) (water hhes) and dendrobine (121) Dendrobium nobikl indl. (Orchidaceae) (Table 11). 

Dendrobine methiodide is convertible into the methohydroxide, m.p. 251° dec.). With cyanogen bromide cyanonordendrobine, m.p. 188°, was obtained, from which nordendrobine, m.p. 117-8°, — 21-6°... 

EtOH), was prepared via the carbamide. Dendrobine has also been prepared by Chen and Chen, who record for certain of the salts, m.ps. different from those given above, e.g., B. HCl, m.p. 193°, B. HI, m.p. 284-5°, but whose data are otherwise in agreement with those of Suzuki et al. 

Chen et al. state that dendrobine produces moderate hyperglycemia, diminishes cardiac activity in large doses, lowers blood pressure, depresses respiration, inhibits isolated rabbit intestine and contracts isolated guinea-pig uterus. It has a weak analgesic, antipyretic action. Chen and Rose found that the convulsions induced by injection of dendrobine can be controlled by use of sodium isoamylethylbarbiturate they appear to be central in origin due to action on the cord and medulla. 

Bicyclic compounds of structure (4) are needed for the synthesis of the alkaloid dendrobine. What is the starting material for a Diels-Alder synthesis of (4) Stereochemistry is obviously vital here. 

Roush gives an analysis of how he came to choose (4) as an intermediate and how it was developed into dendrobine. Another synthesis of dendrobine... 

The dopaminergic potential of the Dendrobium species is, to date, open for exploration. An interesting feature of the Dendrobium species is their ability to elaborate sesquiterpene alkaloids, the chemical structure of which resembles the one of strychnine. One such alkaloid is dendrobine, which is widespread in the genus. Kudo et al. noted that dendrobine, isolated from Dendrobium nobile, exhibits a strychnine-like presynaptic inhibition in frog spinal cord (64). 

Kudo Y, Tanaka A, Yamada K. Dendrobine, an antagonist of beta-alanine, taurine and of presynaptic inhibition in the frog spinal cord. Br J Pharmacol 1983 78 709-715. 

During the course of a short and efficient total synthesis of (-) -dendrobine (3-76), an alkaloid which exhibits antipyretic and hypotensive activities [37], a new domino radical sequence has been exploited by Cassayre and Zard which involves the cycli-... 

Cycloaddition reactions of furans are still widely used as key steps in the construction of complex molecules including natural products. As an example, the intramolecular Diels-Alder cycloaddition of 2-amido substituted furans provides a useful tool for the synthesis of fused, nitrogen-containing poly-heterocycles. Thus, thermolysis of 3-substituted amidofuran produces tricyclic indolinone 39 as a 2 1 mixture of diastereomers via amidofuran cycloaddition-rearrangement methodology, which serves as a key intermediate in the total synthesis of ( )-dendrobine, a major component of the Chinese ornamental orchid Dendrobium nobile . 

Dendritic polymers, fullerene, 12 252 Dendritic salt, 22 805 Dendritic siloxanes, synthesis of, 22 554 Dendrobine, 2 102... 

Introduction of a quaternary carbon center is readily achieved by PKR. Takano and Zard independently employed this methodology for the synthesis of (—)-dendrobin (Equation (44)). ... 

Dendrobium nobile Lindl. Shi Dou (Orchid) (stem) Dendrobine.50 Analgesic, hyperglycemic, hypotensive, hypothermic. 

Dendrobine at a dose of 3 X 10-5 M reduced the dorsal root potential and reflex. It provoked a mild hyperpolarization in both dorsal and ventral roots of frog isolated spinal cord. It affected the (3-alanine- and taurine-induced depolarization of primary afferent terminals and reversibly blocked the presynaptic inhibition caused by antidromic conditioning stimulation of the ventral root potential induced by repetitive antidromic stimulation of ventral root and lowered maximum. It would be interesting to learn whether further research of the Dendrobium species discloses any alkaloid interfering with the glycinergic system, an aspect discussed under the following heading. 

The 1,6-diene 254 was prepared from (+)-carvone (253). Its oxidative cyclization affords the zirconacycle 255, and its carbonylation, followed by treatment with iodine and HC1, gave the tricyclic ketone 256 [113]. The alkaloid (—)-dendrobine (257) was synthesized from 256. 

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... 

The enol acetate 77 of 3,4-dihydro-7-methoxy-5-methyl-l-(2l/)-naphthalenone was converted to the acid 78 by ozonolysis and hydrolysis and this by a Wittig reaction with a-methoxyethyltriphenyl-phosphonium chloride gave 79. Compound 79 was converted into 80 by a series of reactions, five in number, which in turn was converted into 81 by reaction with potassium in -butanol. The methyl ester of compound 81, one isomer of which was recognized as that having the correct stereo structure, was converted to 82 by heating with acetic anhydride and 10-camphorsulfonic acid. Subsequent steps involved ozonization, reaction with V,iV -carbonyldiimidazole, lactam formation, reaction with pyridinium bromide perbromide, reaction with sodium hydride, and a further series in which (+ )-oxodendrobine (83) was ultimately obtained. Reduction of the latter to ( )-dendrobine... 

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