Nitraria alkaloids

Even enantioselective oxidations of some alkyl-, benzyl-, or phenylethyl- (arylethyl-) amines were reported with diamine oxidase from pea settlings 141 f Porcine kidney diamine oxidase was used for the oxidative transformation of Nitraria alkaloids such as nazlinin 421. 

Park et al. also reported an analogous strategy for the synthesis of (+)-isonitramine (107) [61], A phase-transfer catalyzed enantioselective ot-alkylation of lactam 108, followed by subsequent manipulations, was employed for the successful total synthesis of the Nitraria alkaloid (+)-isonitramine (107) (Scheme 21). 

The 2-azaspiro[5.5]undecane group of alkaloids occur in certain plants of the genus Nitraria. There has been some interest in the biological activity of these alkaloids because their structures are similar to the histrionicotoxins, a group of... 

Tulyaganov, T. S. and Allaberdiev, F. K. 2001. Alkaloids of Nitraria sibirica. Dihydroschoberine and nitrabirine N-oxide. Chemistry of Natural Compounds, 37(6) 556-558. 

Nitraramine and A-hydroxynitraramine were isolated from Nitraria schoberi (194,195). There are active hydrogen absorption bands in the IR spectrum of nitraramine at 3280 and 3530 cm- and a low intensity band at 1660 cm" (double bond). Acetylation of nitraramine (171) gave A-acetyl and A,0-diacetyl derivatives. Hydrogenation over Adams catalyst in acetic acid gave di-hydronitraramine (172) and dihydrodesoxynitraramine (173) (Scheme 30). The presence of peaks typical for quinolizidine alkaloids in the mass spectra of 171-... 

Tangutorine (51), Fig. (11), an indole alkaloid recently isolated from the leaves of Nitraria tangutorum [37] constitutes an interesting synthetic target for pharmacological evaluation. The carbon framework of 51 was therefore prepared to investigate, for the first time, the conformational and stereochemical features of this ring system [38]. The epimerization reaction served as a tool in the studies. 

Histrionicotoxins represent a unique structural class of alkaloids found only in dendrobatid frogs (see below). Somewhat similar hydroxy-azaspiro-undecanes, namely, sibirine, nitramine, and isonitramine, occur in certain plants of the genus Nitraria (cf. Ref. 70). 

The conversion of lupanine into camoensidine may represent a biosynthetic pathway, and cleavage of the C-16 C-17 bond of a tetracyclic quinolizidine [cf. mamanine (3)] followed by carbon-carbon cyclization could lead to tetracyclic derivatives containing terminal piperidine rings. New alkaloids of this type have been obtained recently. Aloperine was first isolated from Sophora alopercuroides over forty years ago, and structure (12) has now been assigned to the alkaloid on the basis of spectral studies. Allylaloperine (13) is a constituent of the same species. Nitraramine (14) and 7V-hydroxynitraramine (15) from Nitraria schoberi are... 

A group of alkaloids having a novel structure has been isolated from Nitraria schoberi. The structure of nitrarine (22) was determined by X-ray crystal structure analysis of its dihydrochloride.Nitramidine (23) is a didehydro-derivative, and can be obtained from nitrarine by mercuric acetate oxidation, and schoberidine (24) is... 

Nitramine and isonitramine alkaloids of Nitraria spp., previously described as decahydroquinolines, are now considered to be the epimeric spiropiperidines (104 and (105) respectively (A.A. Ibragimov et al, Khim.prirod. Soedin., 1981, 623 Z. Osmanov et al, ibid, 1982, 126),... 

Synthesis of (—)-Sibirine. Various types of alkaloids have been prepared by conjugate addition of carbon-centered radicals to unsaturated sulfones. This approach is used in the stereoselective synthesis of the Nitraria spirocyclic alkaloid (—)-sibirine, where a 6-exo-trig radical cyclization to an a,(3-unsaturated sulfone leads to the spirocyclic skeleton of the natural product (Eq. 153).263 The y-nitrogen-functionalized sulfone so obtained is then desulfonylated under dissolving-metal conditions. 

Two pentacyclic bases containing tryptamine units and a second nitrogen have been reported. The structure (18) for nitrarine, an optically inactive base from Nitraria schoberi, relies at the moment on spectral measurements. Elaeocarpidine, an optically inactive alkaloid which co-occurs with indolizidine alkaloids in Elaeocarpus densijiorus, has been examined fully and proved to have the structure (19). Central to the structure determination was a hydro-genolysis, in acid solution, of the N-C-N system to give dihydroelaeocarpidine... 

A biological equivalent of a Pictet-Spengler reaction has been proposed to account for the formation of tangutorine, a racemic alkaloid isolated from a Nitraria species. Alkaloids in this species appear to be derived from lysine and a dimeric condensation product of glutaraldehyde is a biomimetic analog. When this material was synthesized and allowed to react with tryptamine, a tangutorine structure was obtained and was converted to material identical to the natural product [362]. 

Decahydroquinoline Alkaloids.—A new decahydroquinoline alkaloid, iso-nitramine (29), has been isolated from Nitraria sibirica, its structure being inferred from spectral measurements. ... 

CioHijNO, Mr 169.27 (+)-form a piperidine alkaloid from Nitraria schoberi (Zygophyllaceae), oil, [alo -h16.5° (CHCI3) (-)-Af-methyl-N. sibirine (C11H21NO, Mr 183.29), from Nitraria sibirica, oil, [a]g -22.5°(CHCl3). 

Alkaloids derived from aeetate, dihydroschoberine, and nitrabirine iV-oxide have been found in the genus Nitraria (Nitraria Pall.) from the Siberian nitraria (Nitraria sibirica Pall.). " In Nitraria komarovii (I. et. L.), komavine and acetylkomavine have been detected. Alkaloids are found... 

Tulyaganov TS, Nazarov OM, Levkovich MG, Abdullaev ND. Alkaloids of die Nitraria genus. Komavine and acetylkomavine. Chem Nat Comp 2001 37(1) ... 

Gravel E, Harfouche A, Salame R, Leblanc K, Maciuk A, Poupon E. Spontaneous formation of nitrarine and polycyclic dceletons related to Nitraria indolic alkaloids under non-enzymatic conditions. Chem Eur J 2013 19(43) 14515-20. 

Plants of the Nitraria genus have yielded a large number of structurally unusual alkaloids [77]. Poupon has reported a very straightforward biomimetic synthesis of one of these compounds, tangutorine, that starts from compound 98, readily available from a double aldol reaction between two molecules of glutaraldehyde. Treatment of 98 with tryptamine under mildly acidic conditions directly afforded compound 100 via a Michael/Pictet-Spengler domino process, and a final reduction step afforded tangutorine 101 (Scheme 3.31) [78]. 

For a review of the chemistry of these alkaloids, see GraveL E., Poupon, E. (2010). Biosynthesis and hiomimetic synthesis of alkaloids isolated from plants of the Nitraria and Myriotieuwn genera an unusual lysine-based metaboUsm. Natural Product Reports, 27, 32-56. 

---