Alkaloids, Prosopis

Juliprosine, isolated from Prosopis juliflora A.DC., has the structure (1). Reduction of the dihydroindolizinium system gives a hexahydroderivative identical with the product from catalytic hydrogenation of the closely related alkaloid juliprosopine (cf. 

In an alternative approach to the nitrone method for the synthesis of Elaeocarpus alkaloids (cf. vol.ll, p.61), a 1,3 dipolar cycloaddition of 1-pyrroline 1-oxlde to a substituted enone gives the isoxazolidine (2), which was converted in a number of steps into the compound (3), the C-7 epimer of elaeokanine C. Oxidation of the epimer (3) afforded the diketone (4), an intermediate in a previously published synthesis of ( )-elaeokanlne C. 

Acid-catalyzed cycllzation of the hydroxylactam (5) to give the chloro compound (6) is the basis for a new synthesis of ( )-elaeo-kanine B (7).  

The synthesis of indolizidine alkaloids, including tylophorine and 6-coniceine as well as Elaeocarpus alkaloids, by the intramolecular imino Diels-Alder method (cf. vol.12, p.71) has been pub- 

New syntheses of ( )-gephyrotoxin and of depentyIperhydrogeph-yrotoxin have been described. 

Juliprosopine from Prosopis juliflora A. DC. is a new type of indolizidine alkaloid, and on the basis of an extensive spectroscopic and chemical study it has been assigned the structure (2), in which relative configurations are shown for the substituents on the piperidine ring. Juliprosopine may be derived biosynthetically from combination of a dihydropyrrole unit with two Prosopis piperidine alkaloids that have C12 side-chains.2 

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In conclusion, an efficient asymmetric synthesis of the prosopis alkaloid (+) -2-epi-deoxoprosopinine was successfully carried out in 11 steps to afford the target... 

Alkaloids containing a 2,6-dialkylated piperidine ring are found abundantly in nature and the Prosopis alkaloids, one of the subgroups of these alkaloids, could possess local anesthetic activity. (-)-Deoxoprosopinine and (—)-deoxoprosophyUine were enantiospecilically and stereoselectively synthesized from methyl 3,4-dideoxy-a-D-eryt/tro-hexopyranoside. The key intermediate 299 was prepared by standard procedures and the dialkylated piperidine ring was formed in the key step by Pd(0)-catalyzed intramolecular N-alkylation of 299. The cyclization proceeded at room temperature when 299 was treated with NaH in THF in the presence of 1 equiv of n-BujNI and a catalytic amount of Pd(PPh3)4 (Scheme 75). 

In addition to lupines, poison-hemlock and Nicotiana spp., other plant species of the genera Genista, Prosopis, Lobelia, Cytisus, Sophora, Pinus, Punica, Duboisia, Sedum, Withania, Carica, Hydrangea, Dichroa, Cassia, Ammondendron, Liparia, and Colidium contain potentially toxic and teratogenic piperidine alkaloids. Many plant species or varieties from these genera may be included in animal and human diets (Keeler and Crowe, 1984). 

Stereoselective total syntheses of (-)-deoxoprosopinine (20) and (-)-deoxoprosophylline (21), derived respectively from the natural bases prosopinine and prosophylline, have been described the route adopted should be applicable to other related piperidine bases.20 Prosafrinine (22), a piperidine alkaloid of Prosopis africana, has been synthesized stereoselectively, along with pseudocar-pamic acid (23), as racemic varieties.21 Additional stereoselective syntheses of ( )-carpamic and ( )-azimic acids have been described.22... 

A number of a, a -disubstituted 3-piperidinol alkaloids have been found in Cassia or Prosopis species,[1] and, quite recently, alkaloids including this structural unit have also been isolated from ascidian.[2] Many of these alkaloids showed interesting pharmacological activities such as anesthetic, analgestic, and antibiotic activities. Clavepictines A and B, and pictamine, isolated from tunicate, by Cardellina, II[3] or Faulkner[4] and co-workers, possess 3-piperidinol structure. Lepadins A, B, and C, isolated from tunicate, by Steffan[5] and Andersen[6] and coworkers, also have this structural unit. We designed lactam 1 as a useful... 

The total synthesis of the racemic form of prosophylline (10), an alkaloid of African mimosa (Prosopis africana), has been described it is outlined in Scheme 3.16 Full details of an earlier reported synthetic endeavour, leading to (—)-deoxoprosophylline and to (—)-deoxoprosopinine (11), have appeared.17... 

For alkaloids isolated from Prosopis or Microcos philippinensis species, see (a) G. Ratle, X. Monseur, B. C. Das, J. Yassi, Q. Khuong-Huu, R. Goutarel, Bull. Soc. 

Juliprosopine (318) and juliprosine (319) (Fig. 5), indolizidine alkaloids of the genus Prosopis (mesquite family Leguminosae), had been partially characterized at the time of the previous review on the topic in this serial (7). Rather few advances have been made since then no further stereochemical clarification has been forthcoming, and no further work has been reported on two other putative Prosopis indolizidines, isojuliprosopine and isojuliprosine (295). However, the alkaloid juliflorine, previously isolated from Prosopis juliflora by workers from Pakistan (296,297), has since been shown to be identical to juliprosopine (298). 

Two further indolizidine alkaloids, juliprosinene ([a]o +9.5° for the chloride salt, c 0.04, CHCI3) and juliflorinine ([a]o +3.9°, c 0.03, CHCI3), were isolated from the leaves of Prosopis juUflora some years after the above work had been reported (299). Partial structures were once again deduced on the basis of extensive spectro-scopic comparisons with known alkaloids. Juliprosinene chloride, for instance, gave very similar spectra to juliprosine (319) and spectaline (320), and showed no doubling up... 

Prosophylline (1) and (-)-prosopinine (2) are naturally occurring alkaloids isolated from the leaves of the African mimosa Proiopw africana Taub, which are used in indigenous medicine. These alkaloids possess a variety of antibiotic and anesthetic properties The racemic alkaloid of (-)-desoxoprosophylline (3), (-)-desoxoprosopinine (4) and (+)-prosafrinine (5) ° have been isolated from the same plant Prosopis africana ... 

From Prosopis africana Taub., which has been used in Africa as a remedy for toothache and other ailments, two alkaloids related to carpaine and cassine have been isolated 183). Prosopine (CXXI R = H, OH), C18H37NO3 (mp 126°) has three hydroxyl groups and a secondary amino group. Prosopinine (CXXII R = 0), C18H35NO3 (mp 95°), has two hydroxyls, a secondary amino group, and a keto group. 

Three new alkaloids have been isolated from the leaves of Prosopis juliflora DC. (mesquite). The minor base, julifloridine, has been examined spectroscopically, and structure (21), of unspecified relative and absolute configuration, has been advanced for it. The other two bases, juliflorine and julifloricine, are also 3-hydroxy-2-methyl-piperidines of apparently more complex structure.Spec-talinine (22) and iso-6-carnavaline (23) are two new piperidine bases occurring in... 

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