- Synthesis of the alkaloids (-)-heliotridane and (-)-isoretronecanol via π-allyltricarbonyliron lactam complexes
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A novel synthesis of the pyrrolizidine alkaloids (-)-heliotridane (1) and (-)-isoretronecanol (2) is described. The key steps involve the conversion of a proline-derived carbamate (10) into the π-allyltricarbonyliron lactam complex (4) and the exhaustive carbonylation of this to give the pivotal intermediate γ-lactam (3). Lactam (3) has been converted into the title compounds by standard methods
- Knight,Ley
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- Asymmetric syntheses of (-)-isoretronecanol and (-)-trachelantamidine
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Short and concise total asymmetric syntheses of (-)-isoretronecanol and (-)-trachelantamidine are reported. Oxidative cleavage of tert-butyl (S,S,S,Z)-7-[N-benzyl-N-(α-methylbenzyl)amino]cyclohept-3-ene-1- carboxylate, followed by hydrogenolysis promoted
- Brambilla, Marta,Davies, Stephen G.,Fletcher, Ai M.,Roberts, Paul M.,Thomson, James E.
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- Stereodivergent Synthesis of 1-Hydroxymethylpyrrolizidine Alkaloids
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A first stereodivergent strategy for the asymmetric synthesis of all stereoisomers of 1-hydroxymethylpyrrolizidine alkaloids is developed using an asymmetric self-Mannich reaction as a key step. An anti-selective self-Mannich reaction of methyl 4-oxobutanoate with the PMP-amine catalyzed by a chiral secondary amine is successfully optimized for the asymmetric synthesis of (+)-isoretronecanol and (-)-isoretronecanol. A syn-selective self-Mannich reaction catalyzed by proline is utilized for the asymmetric synthesis of the diastereomer, (+)-laburnine, and its enantiomer, (-)-trachelanthamidine.
- Appayee, Chandrakumar,Sarkale, Abhijeet M.
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- ORGANIC REACTIONS
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The present invention relates to various organic reactions including a method for producing heterocyclic compounds using a [3+2] annulation; a method for producing fluorinated heteroaromatic compounds; and a method for alkylating a meta-position of a phen
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Paragraph 0094
(2016/02/18)
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- Asymmetric [3+2] Annulation Approach to 3-Pyrrolines: Concise Total Syntheses of (-)-Supinidine, (-)-Isoretronecanol, and (+)-Elacomine
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An asymmetric [3+2] annulation reaction to form 3-pyrroline products is reported. Upon treatment with lithium diisopropylamide, readily available ethyl 4-bromocrotonate is deprotonated and trapped with Ellman imines selectively at the α-position to yield enantiopure 3-pyrroline products. This new method is compatible with aryl, alkyl, and vinyl imines. The efficacy of the method is showcased by short asymmetric total syntheses of (-)-supinidine, (-)-isoretronecanol, and (+)-elacomine. This novel annulation approach also works for an aldehyde, thus providing access to a 2,5-dihydrofuran product in a single step from simple precursors. By modifying the structure of the carbanion nucleophile, an asymmetric vinylogous aza-Darzens reaction can be realized.
- Chogii, Isaac,Njardarson, Jon T.
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supporting information
p. 13706 - 13710
(2015/11/16)
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- Organocatalytic asymmetric mannich cyclization of hydroxylactams with acetals: Total syntheses of ( )-epilupinine, ( )-tashiromine, and ( )-trachelanthamidine
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An asymmetric, organocatalytic, one-pot Mannich cyclization between a hydroxylactam and acetal is described to provide fused, bicyclic alkaloids bearing a bridgehead N atom. Both aliphatic and aromatic substrates were used in this transformation to furnish chiral pyrrolizidinone, indolizidinone, and quinolizidinone derivatives in up to 89% yield and 97% ee. The total syntheses of (-)-epilupinine, (-)-tashiromine, and (-)-trachelanthamidine also achieved to demonstrate the generality of the process.
- Koley, Dipankar,Krishna, Yarkali,Srinivas, Kyatham,Khan, Afsar Ali,Kant, Ruchir
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p. 13196 - 13200
(2015/02/19)
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- Pyrrolizidine alkaloids from Liparis nervosa with inhibitory activities against LPS-induced NO production in RAW264.7 macrophages
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Six pyrrolizidine alkaloids were isolated from the whole herb of Liparis nervosa together with two previously known ones. Their structures were elucidated by extensive spectroscopic analyses and chemical reactions. The cytotoxicity of the isolates was eva
- Huang, Shuai,Zhou, Xian-Li,Wang, Cui-Juan,Wang, You-Song,Xiao, Feng,Shan, Lian-Hai,Guo, Zhi-Yun,Weng, Jie
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p. 154 - 161
(2013/10/21)
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- Cremastrine, a pyrrolizidine alkaloid from Cremastra appendiculata
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A new pyrrolizidine alkaloid, cremastrine (1), was isolated from the bulbs of Cremastra appendiculata. Its configuration was determined by spectroscopic and chemical analyses. Compound 1 inhibited the binding of tritium-labeled N-methylscopolamine to the muscarinic M3 receptor with a Ki value of 126 nM.
- Ikeda, Yoshitaka,Nonaka, Hikaru,Furumai, Tamotsu,Igarashi, Yasuhiro
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p. 572 - 573
(2008/09/20)
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- Highly efficient and stereoselective radical addition of tertiary amines to electron-deficient alkenes - Application to the enantioselective synthesis of necine bases
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A convenient and highly efficient method for the regio- and stereoselective addition of tertiary amines to electron-deficient alkenes has been elaborated. It is based on a radical chain reaction of α-aminyl radicals with alkenes, induced by a photoelectro
- Bertrand, Samuel,Hoffmann, Norbert,Pete, Jean-Pierre
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p. 2227 - 2238
(2007/10/03)
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- Stereoselective radical addition of tertiary amines to (5R)-5- menthyloxy-2[5H]-furanone: Application to the enantioselective synthesis of (-)-isoretronecanol and (+)-labumine
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The adducts of a stereoselective radical addition of tertiary amines with (5R)-5-menthyloxy-2[5H]-furanone were transformed very efficiently into enantiomerically pure pyrrolizidine and indolizidine alkaloids, through a three steps sequence.
- Bertrand, Samuel,Hoffmann, Norbert,Pete, Jean-Pierre
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p. 3173 - 3174
(2007/10/03)
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- Enamino ester reduction: A short enantioselective route to pyrrolizidine and indolizidine alkaloids. Synthesis of (+)-laburnine, (+)-tashiromine, and (-)-isoretronecanol
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Various chiral pyrrolidine tetrasubstituted β-enamino esters were reduced catalytically or chemically with good to moderate diastereoselectivity owing to a chiral induction originated from (S)-α- methylbenzylamine. With endocyclic double bond compounds, t
- David, Olivier,Blot, Jerome,Bellec, Christian,Fargeau-Bellassoued, Marie-Claude,Haviari, Gjergj,Celerier, Jean-Pierre,Lhommet, Gerard,Gramain, Jean-Claude,Gardette, Daniel
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p. 3122 - 3131
(2007/10/03)
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- An enantio- and diastereoselective synthesis of (-)-isoretronecanol and (+)-trachelanthamidine from a meso precursor
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Two diastereomeric pyrrolizidine alkaloids, (-)-isoretronecanol and (+)- trachelanthamidine, have been synthesized in an enantio- and diastereoselective manner starting from a meso precursor via a catalytic asymmetrization.
- Konno, Hiroyuki,Kishi, Masayo,Hiroya, Kou,Ogasawara, Kunio
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- Homoproline homologation by enolate Claisen rearrangement or direct allylation: Syntheses of (-)-trachelanthamidine, (-)-isoretronecanol and (±)-turneforcidine
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The pyrrolizidine precursors 13 and 14 are obtained both by enolate Clalsen rearrangement of the homoproline allyl ester 12 and by direct allylation of N-protected homoproline ethyl ester 15. In both cases, the reactions show poor levels of stereoselectivity. Reduction gives the corresponding alcohols 20a and 21 a which are separated and subsequently elaborated to (-)-trachelanthamidine 24 and (-)-isoretronecanol 25 respectively via reductive alkene cleavage, mesylation and spontaneous cyclisation following N-deprotection. The chiral integrity of the original proline-derived asymmetric centre is preserved throughout. A similar enolate allylation gives, with high stereoselectivity, the homologue 34 of the Geissman-Waiss lactone 32, which is similarly transformed into (±)-turneforcidine 31.
- Knight, David W.,Share, Andrew C.,Gallagher, Peter T.
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p. 2089 - 2097
(2007/10/03)
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- Asymmetric Radical Cyclization With Pyroglutamate: Synthesis of 7-Substituted Pyrrolizidinones
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Chiral, non-racemic N-(2-iodoethyl)-5-vinylpyrrolidin-2-ones have been synthesized and then cyclized with tributyltin hydride and azoisobutyronitrile (AIBN) to produce chiral, non-racemic pyrrolizidin-2-ones, with high diastereoselectivity.Reduction of the lactam moiety provides a facile route to naturally occuring pyrrolizidine alkaloids.
- Keusenkothen, Paul F.,Smith, Michael B.
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p. 2485 - 2492
(2007/10/02)
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- Synthesis of (-)-Heliotridane and (-)-Isoretronecanol via Diastereoselective Conjugate Addition of Organocuprates to an Enoate Deriving from Proline
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A synthesis of the pyrrolizidine alkaloids (-)-heliotridane and (-)-isoretronecanol and their epimers is described.The key step involves a diastereoselective conjugate addition of organocuprates to (2S)-N-(tert-butoxycarbonyl)-2-pyrrolidine (2) deriving from (S)-proline.
- Coz, Sylvie Le,Mann, Andre,Thareau, Frederic,Taddei, Maurizio
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p. 2073 - 2080
(2007/10/02)
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- Asymmetric Synthesis with Chiral Hydrogenolysable Amines. A Short Synthesis of (-) Isoretronecanol
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Dihydropyrrole prepared from (S)-α-methylbenzylamine is reduced with high diastereomeric excess.A short non epimeric route to isoretronecanol is reported.
- Haviari, G.,Celerier, J. P.,Petit, H.,Lhommet, G.
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p. 1599 - 1600
(2007/10/02)
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- Synthesis of the pyrrolizidines (-)-trachelanthamidine and (-)-isoretronecanol
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(-)-Trachelanthamidine, 12, and (-)-isoretronecanol, 14, have been prepared from (S)-2-pyrrolidineacetic acid by α-allylation using either a Claisen rearrangement or direct enolate alkylation followed by cleavage of the side-chain and cyclisation
- Knight, David W.,Share, Andrew C.,Gallagher, Peter T.
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- Synthesis of Necine Bases from Homoproline Derivatives
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The α-allyl homoproline ester 8, obtained by Claisen rearrangement of the allyl ester 7 or direct C-allylation of the homoproline methyl ester 9 has been converted into (-)-trachelanthamidine 4a and (-)-isoretronecanol 4b while allylation of the enolate derived from the lactone 13a followed by related transformations leads stereospecifically to turneforcidine 12.
- Knight, David, W.,Share, Andrew C.,Gallagher, Peter T.
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p. 1615 - 1616
(2007/10/02)
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- A NEW SYNTHESIS OF (-)-ISORETRONECANOL AND (-)-TRACHELANTHAMIDINE THROUGH ORTHOESTER CLAISEN REARRANGEMENT FOR ALLYLIC ALCOHOL FUNCTIONALITY TAGGED AT C(2) OF PYRROLIDINE AS A KEY STEP
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Orthoester Claisen rearrangement of (2S)-2--pyrrolidine derived from (S)-proline gave (2S)-2--N-(t-butoxycarbonyl)-pyrrolidine which is ready for further elaboration directed to necine base skeleton.Title compounds have been synthesized using this key intermediate.
- Moriwake, Toshio,Hamano, Shin-ichi,Saito, Seiki
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p. 1135 - 1140
(2007/10/02)
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- MINOR ALKALOIDS OF HELIOTROPIUM CURASSAVICUM
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Isolation and structure determination of the minor alkaloids of Heliotropium curassavicum are described.These include the new pyrrolizidine alkaloids, heliocurassavine , heliocoromandaline , heliocurassavicine , heliocurassavinine , curassavinine , coromandalinine , heliovinine and curassanecine .Structures were established by high resolution 1H NMR, mass spectrometry and paper electrophoresis of the alkaloids and their hydrolysis products. - Key Word Index-Pyrrolizidine alkaloids; heliocurassavine; heliocurassavinine; heliocurassavicine; heliocoromadaline; curassavinine; coromandalinine; heliovinine; curassanecine.
- Mohanraj, Subramaniam,Subramanian, Polur S.,Herz, Werner
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p. 1775 - 1780
(2007/10/02)
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- THE SYNTHESIS OF (-)-ISORETRONECANOL, (-)-TRACHELANTHAMIDINE, AND (-)-SUPINIDINE FROM (S)-PROLINE
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Dieckmann cyclisation of (S)-N,2-di(carboethoxymethyl)pyrrolidine, made from (S)-proline, gave (8S)-1-carboethoxypyrrolizidin-2-one, which was then converted into (-)-isoretronecanol, (-)-trachelanthamidine, and (-)-supinidine.
- Rueeger, Heinrich,Benn, Michael
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p. 1677 - 1680
(2007/10/02)
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- Synthesis of Optically Active Pyrrolizidine Bases
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Regiospecific 1,3-dipolar cycloaddition of ethyl propiolate to the NO-diformyl derivative (1) of natural (-)-4-hydroxy-L-proline followed by stereospecific hydrogenation gave ethyl (+)-6α-hydroxy-β-pyrrolizidine-1α-carboxylate (4).Confirmation of the abso
- Robins, David J.,Sakdarat, Santi
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p. 909 - 913
(2007/10/02)
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