Quinolizidine-1-methanol

One can find a number of methods of quinolizidine alkaloid extraction within existing literature. The most frequently applied methods are extraction by alcohols (50% methanol or 96% ethanol, or these alkaloids with a 1% addition of glacial acetic acid). 

Quinolizine (Pyridocoline). Quinolizine (32) does not appear to have ever been prepared in a pure state. However, quinolizinium iodide (33)117 and dehydroquinolizinium iodide (34)117 118 were readily hydrogenated over Adams platinum oxide in ethanol to yield quinolizidine hydroiodide with the uptake of 4 and 5 equiv of hydrogen, respectively (eq. 12.61). Similarly, 2-methyldehydro-quinolizinium iodide rapidly absorbed 5 mol of hydrogen over platinum oxide in methanol to give octahydro-2-methylquinolizine.119... 

In the synthesis of lupinine125 optically active quinolizidine esters have been reduced by sodium borohydride in methanol to the corresponding saturated systems, which furnished ( + ) and (— )-lupinine by treatment with lithium aluminum hydride (Scheme 94). 

A biomimetic approach to the quinolizidine alkaloid lamprolobine (193) <9iT843l> exploits the cyclization of the bispiperidine system (190) by treatment with ammonia in methanol. This reaction affords a mixture of quinolizidines (191) and (192), whose ratio can be shifted in favor of the minor isomer (192) by equilibration in the presence of dbu. Compound (192) displays suitable stereoehemistry to act as a precursor of lamprolobine (Scheme 33). 

In a reaction related to the transformation ((226)-> (228)), acid-promoted cyclization of the hydroxylactam (229) afforded a 7 3 mixture of the quinolizidines (230) and (231), easily transformed into the alkaloids myrtine and epimyrtine (Scheme 44) <92TL73). Related hydroxylactams bearing bromoalkynyl substituents can also give similar cyclizations. For example, treatment of compound (232) with trifluoroacetic acid and methanol afforded a 45 55 mixture of the quinolizidines (233) and (234), precursors of lupinine and epilupinine (Equation (22)) <92TL3633>. 

Quantitative analysis of quinolizidine alkaloids in Chinese herbs 1% acetic acid, 50 mM ammonium acetate, 20% acetonitrile in methanol NACE [185]... 

In order to introduce a carbon unit into the 2-position of the quinolizidine skeleton which would be obtained by ring cleavage of the dihydrofuran ring, we have investigated Michael type addition to the p -position of the enone moiety. When the tetrahydrofuran was treated with LDA at -78 followed by treatment of methanol, the tetrafuran ring was nicely cleaved as expected to afford the enone with 2-hydroxyethyl group at the 3-position in good yield. 

A soln. of l-(y6-3-indolylethyl)-2,3-dihydro-4-pyridone in methanol treated with 10%-H2S04, and allowed to stand 0.5 hr. at room temp. l-oxoindolo[2.3-a]-quinolizidine. Y 95%. E. Winterfeldt, B. 97, 2463 (1964). 

Another short synthesis of ( )-9a-ep(-quinolizidine 195C (rat-2318), by Mann and coworkers, is worth mentioning in view of its use of a Hnear hydroformylation of a homoallylamine (cyclohydrocarbonylation) to constmct the piperidine ring (Scheme 296). ° A three-component aza-Hosomi—Sakurai reaction between allyltrimethylsilane, butanal, and O-benzylurethane catalyzed by boron trifluoride was used to form the protected homoallylamine ( )-2319. The cyclohydrocarbonylation was then performed with a biphephos/rhodium(I) catalytic system in methanol, yielding the piperidine-containing hemiaminal 2320 in 84% yield. This... 

From the methanolic extract of sun-dried specimens of the sponge Petrosia seriata Braekman et al. 194) isolated a novel type of bis-quinolizidine alkaloid, the ichthyotoxic petrosin (312), and determined its structure by X-ray diffraction. 312, which contains a C-16 macrocycle, was toxic to the fish Lebistes reticulatus (LD = 50mg/L). Later,... 

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