- 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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- ABSOLUTE CONFIGURATION OF (+)-5,6-DEHYDROLUPANINE, A KEY INTERMEDIATE IN BIOSYNTHESIS OF LUPIN ALKALOIDS
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(+)-5,6-Dehydrolupanine, a key intermediate in biosynthesis of lupin alkaloids, was isolated from Thermopsis chinensis.The absolute configuration of the compound was determined to be 7R,9R,11R by chemical transformation to (-)-lupanine.Key Word Index - Thermopsis chinensis; Leguminosae; aerial parts; lupin alkaloid; quinolizidine alkaloid; (+)-5,6-dehydrolupanine; lupanine; absolute configuration; biosynthesis.
- Saito, Kazuki,Takamatsu, Satoshi,Sekine, Toshikazu,Ikegami, Fumio,Ohmiya, Shigeru,et al.
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p. 958 - 959
(2007/10/02)
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- Synthesis of Cadaverine and its Incorporation into five Quinolizidine Alkaloids
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Cadaverine dihydrochloride (13) was synthesised by the sequential introduction of two equivalents of sodium cyanide to a C3 precursor, and it was fed to Lupinus luteus and L. polyphyllus plants.Complete labelling patterns were obtained in five quinolizidine alkaloids by 13C n.m.r. spectroscopy.The 13C-13C doublets observed in the spectra of (-)-lupinine (3), (-)-sparteine (4), (+)-lupanine (5), (+)-13α-hydroxylupanine (6), and (+)-angustifoline (7) derived biosynthetically from the doubly labelled precursor (13) confirm the intact, specific incorporation of two cadaverine units into the tetracyclic quinolizidine alkaloid skeletons.The cadaverine (13) units are incorporated to about the same extent into each part of the quinolizidine alkaloids (3)-(7).Two of the 13C chemical shifts for lupanine (5) have been reassigned.The labelling pattern of the tricyclic alkaloid angustifoline (7) indicates that the allyl group originates by degradation of one ring of a tetracyclic precursor.
- Robins, David J.,Sheldrake, Gary N.
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p. 2101 - 2120
(2007/10/02)
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- Lactams of sparteine
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(2,2-2H2)Sparteine, (6-2H)sparteine, (10,10-2H2)sparteine, (15,15-2H2)sparteine, (17α-2H)sparteine, (17β-2H)sparteine, (17,17-2H2)sparteine, (17α-2H)lupanine, and (17β-2H)lupanine were prepared and employed to assign the 1H nmr spectrum of sparteine.Contrary to a published report, photochemical oxidation of sparteine does not lead to 15-oxosparteine but to 17-oxosparteine.
- Golebiewski, W. Marek,Spenser, Ian D.
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p. 716 - 719
(2007/10/02)
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