- Total Synthesis of Indolizidine Alkaloids via Nickel-Catalyzed (4 + 2) Cyclization
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A Ni-catalyzed (4 + 2) cycloaddition of alkynes and azetidinones toward piperidinones was used as key reaction in the enantioselective synthesis of naturally occurring indolizidine alkaloids. The reaction benefits from the use of an easily accessible azet
- Renner, Jonas,Thakur, Ashish,Rutz, Philipp M.,Cowley, Jacob M.,Evangelista, Judah L.,Kumar, Puneet,Prater, Matthew B.,Stolley, Ryan M.,Louie, Janis
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p. 924 - 928
(2020/02/04)
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- Superacid-promoted synthesis of indolizidine derivatives
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A series of amido-acetals were reacted with the Br?nsted superacid, CF3SO3H, to provides indolizidine derives by a cyclization cascade. A mechanism is proposed involving formation of a vinylogous enol which undergoes a 6π-electrocycl
- Kennedy, Sean,Kethe, Anila,Qarah, Ahmad,Klumpp, Douglas A.
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p. 1932 - 1935
(2018/04/16)
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- Synthesis of (+)-Ipalbidine Based on 6-exo-trig Radical Cyclization of a β-Amino Radical
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N-Boc (S)-proline was converted into (2S)-2-[(phenylselanyl)methyl]pyrrolidine, which was alkylated on nitrogen with 2-bromo-1-(4-methoxyphenyl)ethan-1-one. Reaction with vinyllithium, 6-exo-trig radical cyclization (Bu3SnH, AIBN, PhMe, 110 °C), dehydration (P2O5, H3PO4), and demethylation (BBr3) gave (+)-ipalbidine with ee >99%.
- Chea, JongMyoung,Clive, Derrick L. J.
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p. 10294 - 10298
(2015/11/03)
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- Iminium ion-enamine cascade cyclizations: Facile access to structurally diverse azacyclic compounds and natural products
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A one-pot, mild, two-component iminium ion-enamine cascade reaction to construct structurally diverse azacyclic frameworks from l-proline and l-pipecolic acid, and its application to indolizidine and quinolizidine alkaloids and azasteroids, is reported.
- Hanessian, Stephen,Chattopadhyay, Amit Kumar
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p. 232 - 235
(2014/01/23)
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- A simple enantioselective route to functionalized indolizidines: Synthesis of (+)-ipalbidine and (+)-antofine
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An efficient route to functionalized indolizidines from an enantiomerically enriched γ-nitro ketone is described. The nitro ketone is obtained by an organocatalytic, enantioselective ketone-nitro alkene Michael addition. Oxidative ring expansion of the ni
- Pansare, Sunil V.,Lingampally, Rajinikanth,Dyapa, Rajendar
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p. 2235 - 2238
(2011/06/19)
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- Total syntheses of arylindolizidine alkaloids (+)-ipalbidine and (+)-antofine
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This paper presents the first application of two recently developed reactions to natural product synthesis. The first method involves a 6-endo-trig cyclization to prepare a versatile chiral enaminone building block. The second is a direct C-H arylation reaction. As a showcase for the utility of these methods, (+)-antofine and (+)-ipalbidine were synthesized in only 8 steps and 24-26% overall yields.
- Niphakis, Micah J.,Georg, Gunda I.
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supporting information; experimental part
p. 6019 - 6022
(2010/12/19)
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- Enantiospecific synthesis of an indolizidine alkaloid, (+)-ipalbidine
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Enantiospecific total synthesis of an indolizidine alkaloid, ipalbidine, was achieved starting from (-)-pyroglutamic acid by employing an intramolecular McMurry coupling reaction with a low-valent titanium, as a key step.
- Honda, Toshio,Namiki, Hidenori,Nagase, Hiromasa,Mizutani, Hirotake
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p. 3035 - 3038
(2007/10/03)
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- A synthesis of (±)-ipalbidine using sulfur-controlled 6-exo selective radical cyclization of α-phenylthio amide
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A synthesis of (±)-ipalbidine (1) has been achieved using Bu3SnH- mediated 6-exo selective radical cyclization of 2-[3-(phenylthio)prop-2- enyl]-N-[α(p-methoxyphenyl)-α-(phenylthio)acetyl]pyrrolidine (15) as a key step.
- Ikeda, Masazumi,Shikaura, Jiro,Maekawa, Noriko,Daibuzono, Kaori,Teranishi, Hirotaka,Teraoka, Yoshiko,Oda, Norio,Ishibashi, Hiroyuki
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- A Concise Total Synthesis of (+/-)-Ipalbidine by Application of the Aldimine-Diene Cyclocondensation Reaction
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The scope of the diene-imine cyclocondensation reaction has been extended to the unstable Δ1-pyrroline.Cyclocondensation of this compound with the silylketene acetal derived from ethyl 2-p-anisyl-3-methylcrotonate provides the basis for a rapid
- Danishefsky, Samuel J.,Vogel, Claus
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p. 3915 - 3916
(2007/10/02)
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- Intramolecular Carbenoid Reactions of Pyrrole Derivatives. A Total Synthesis of (+/-)-Ipalbidine
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A mew method for alkaloid synthesis is described.The rhodium(II)-acetate-catalyzed decomposition of 3-(4-acetoxyphenyl)-1-diazo-4-(pyrrol-1-yl)-2-butanone (5d) gave 6-(4-acetoxyphenyl)-5,6-dihydro-7(8H)-indolizinone (6d) in 82percent yield via an intramolecular carbenoid reaction.The latter compound was converted in four steps in 13percent overall yield to (+/-)-ipalbidine (1b).
- Jefford, Charles W.,Kubota, Tadatoshi,Zaslona, Alexander
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p. 2048 - 2061
(2007/10/02)
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- SYNTHESIS OF THE ALKALOIDS JULANDINE AND IPALBIDINE - USE OF SILICON (IV) CHLORIDE
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Titanium (IV) chloride and silicon (IV) chloride with high oxygen affinity are the best Lewis acid catalysts, of a number tested, for cyclisation of an enamine-ketone (1) leading to the alkaloid, julandine (2); cyclisation of (6) in methanol solution without catalyst yields O-methylipalbidine (7).
- Cragg, John E.,Hedges, Stuart H.,Herbert, Richard B.
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p. 2127 - 2130
(2007/10/02)
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