- Synthesis of Diels-Alder adducts of the quinolizidine alkaloids N-methylcytisine, (-)-leontidine, and (-)-thermopsine with N-phenylmaleimide
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The Diels-Alder adducts of the quinolizidine alkaloids N-methylcytisine, (-)-leontidine, and (-)-thermopsine with N-phenylmaleimide have been synthesized. The structures and absolute configurations of the new asymmetric centers of the products were determ
- Tsypysheva, Inna P.,Lobov, Alexander N.,Kovalskaya, Alena V.,Vinogradova, Valentina I.,Suponitsky, Kyrill Yu.,Khursan, Sergey L.,Yunusov, Marat S.
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- Thionation of quinolizidine alkaloids and their derivatives via Lawesson’s reagent
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Direct thionation of quinolizidine alkaloids (-)-cytisine, methylcytisine, thermopsine and some of their carbonyl derivatives was realized. It was established that carrying out of the reaction in the boiling toluene with 0.5 eq. of Lawesson’s reagent (LR)
- Koval’skaya, Alena V.,Petrova, Polina R.,Tsypyshev, Dmitry O.,Lobov, Alexander N.,Tsypysheva, Inna P.
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- The Enantioselective Total Synthesis of Bisquinolizidine Alkaloids: A Modular “Inside-Out” Approach
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Bisquinolizidine alkaloids are characterized by a chiral bispidine core (3,7-diazabicyclo[3.3.1]nonane) to which combinations of an α,N-fused 2-pyridone, an endo- or exo-α,N-annulated piperidin(on)e, and an exo-allyl substituent are attached. We developed a modular “inside-out” approach that permits access to most members of this class. Its applicability was proven in the asymmetric synthesis of 21 natural bisquinolizidine alkaloids, among them more than ten first enantioselective total syntheses. Key steps are the first successful preparation of both enantiomers of C2-symmetric 2,6-dioxobispidine by desymmetrization of a 2,4,6,8-tetraoxo precursor, the construction of the α,N-fused 2-pyridone by using an enamine-bromoacrylic acid strategy, and the installation of endo- or, optionally, exo-annulated piperidin(on)es.
- Scharnagel, Dagmar,Goller, Jessica,Deibl, Nicklas,Milius, Wolfgang,Breuning, Matthias
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p. 2432 - 2435
(2018/02/16)
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- (-)-Cytisine: Access to a stereochemically defined and functionally flexible piperidine scaffold
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N-Benzyl cytisine undergoes an efficient C(6)-N(7) cleavage via directed C(6) lithiation, borylation and oxidation to provide a "privileged" heterocyclic core unit comprising a highly functionalised, cis-3,5-disubstituted piperidine in enantiomerically pure form. The potential offered by this unit as a means to explore chemical space has been evaluated and methods have been defined (and illustrated) that allow for selective manipulation of N(1), C(3′), and the pyridone N. The pyridone core can also be diversified via bromination (at C(3′′) and C(5′′)) which is complementary to direct C-H activation based on Ir-catalyzed borylation to provide access to C(4′′). The use of a boronate-based 1,2-migration as an alternative trigger to mediate C(6)-N(7) cleavage of cytisine was evaluated but failed. However, the stability of the intermediate boronate opens a new pathway for the elaboration of cytisine itself using both Matteson homologation and Zweifel olefination.
- Niwetmarin, Worawat,Rego Campello, Hugo,Sparkes, Hazel A.,Aggarwal, Varinder K.,Gallagher, Timothy
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supporting information
p. 5823 - 5832
(2018/08/22)
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- Synthesis and specific nootropic activity of (-)-cytisine derivatives with carbamide and thiocarbamide moieties in their structure
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N-(methylcytisinyl)-N-substituted ureas, N-substituted cytisine-12- carbamides, and cytisine-12- thiocarbamide were prepared by reaction of (-)-cytisine with urea and thiourea and of (-)-cytisine and its 12-N-methyl-3-amino derivative with isocyanates. Their specific nootropic activity was studied in vivo. The therapeutic index was determined for the lead compound. Promising candidates for further pharmacological testing were found.
- Tsypysheva,Koval'skaya,Makara,Lobov,Petrenko,Galkin,Sapozhnikova,Zarudii,Yunusov
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p. 629 - 634
(2013/02/25)
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- Synthesis of (+)-kuraramine
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The first synthesis of (+)-kuraramine via oxidative cleavage of (-)-N-methylcytisine is reported. An alternative but unsuccessful approach to (+)-kuraramine is also described based on extending an intramolecular enolate addition protocol that had previous
- Frigerio, Fabio,Haseler, Claire A.,Gallagher, Timothy
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supporting information; experimental part
p. 729 - 730
(2010/06/19)
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