- Synthesis of indolizidine, pyrrolizidine and quinolizidine ring systems by proline-catalyzed sequential α-amination and HWE olefination of an aldehyde
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A general procedure for the synthesis of azabicyclic ring systems viz. indolizidine, pyrrolizidine and quinolizidine has been developed utilizing proline-catalyzed sequential α-amination and Horner-Wadsworth-Emmons (HWE) olefination of an aldehyde as the key step. This method can be further extended to the synthesis of various biologically active natural products containing azabicyclic ring systems.
- Kauloorkar, Shruti Vandana,Jha, Vishwajeet,Kumar, Pradeep
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p. 18288 - 18291
(2013/10/21)
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- ELECTROLYTE, ELECTROLYTIC SOLUTION, AND ELECTROCHEMICAL DEVICE USING THE SAME
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Disclosed herein is an electrolyte having excellent long-term reliability, a high withstanding voltage (a wide potential window), and high conductivity. The electrolyte contains a quaternary ammonium salt represented by the following general formula (1): wherein R1 represents a hydrocarbon group; R2 represents a hydrocarbon group, a hydrogen atom, or a halogen atom; R3 to R14 each represent an alkyl group, a fluoroalkyl group, a hydrogen atom or a halogen atom, C and C* each represent a carbon atom, N represents a nitrogen atom; h, i, j, x, y, and z are each an integer of 0 to 6, (h+x) is an integer of 0 to 6, (i+y) and (j+z) are each an integer of 1 to 6; and X? represents a counter anion having a HOMO energy of ?0.60 to ?0.20 a.u. as determined by the first-principle calculation on molecular orbital of the counter anion.
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- Hydrogenation of pyrrolizin-3-ones; New routes to pyrrolizidines
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Pyrrolizin-3-ones (e.g.1) can be easily hydrogenated to their hexahydro (pyrrolizidin-3-one) derivatives in the presence of heterogeneous catalysts. Good diastereoselectivity (up to >97:3, depending on catalysts and solvent) can be achieved if the pyrroli
- Despinoy, Xavier L. M.,McNab, Hamish
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experimental part
p. 4502 - 4511
(2009/12/25)
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- A new access to pyrrolizidine derivatives: Ring contraction of methyl (E)-[1,2-oxazin-3-yl]propenoates
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Nitrosoalkene 2 generated in situ from oxime 3 underwent smooth hetero Diels-Alder reaction with enol ethers 1 to afford 1,2-oxazine derivatives 4 bearing an exocyclic C=C bond. Methoxyallene 8 and 2 provided 6H-1,2-oxazine 10 in good overall yield. The exocyclic double bond of this type of 1,2-oxazines can be employed for addition reactions as demonstrated by dihydroxylation of 4a with potassium permanganate, smoothly delivering 1,2-diol 11. A reductive cascade reaction involving ring cleavage at the N-O bond followed by cyclization steps furnished pyrrolizidinone derivatives 12 in good yields. In the case of 12b this transformation proceeded with excellent stereoselectivity. Finally, the lactam moiety of 12 could be reduced with borane to provide the corresponding pyrrolizidine derivatives 19 in good yield. Georg Thieme Verlag Stuttgart.
- Zimmer, Reinhold,Collas, Markus,Czerwonka, Regina,Hain, Ute,Reissig, Hans-Ulrich
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p. 237 - 244
(2008/12/21)
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- Stereochemistry of β-deuterium isotope effects on amine basicity
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Secondary β-deuterium isotope effects on amine basicities are measured using a remarkably precise NMR titration method. Deuteration is found to increase the basicity of methylamine, dimethylamine, benzylamine, N,N-dimethylaniline, 2-methyl-2-azanorbornane, and pyrrolizidine. The increase in dimethylamine arises entirely from enthalpy, contrary to a previous report. The method permits a determination of intramolecular isotope effects in 1-benzyl-4-methylpiperidine and 2-benzyl-2-azanorbornane. It is found that deuteration has a larger isotope effect when either antiperiplanar or synperiplanar to a lone pair, but the synperiplanar effect is smaller, as confirmed by computations. The isotope effect is attributed to a lowered zero-point energy of a C-H bond adjacent to an amine nitrogen, arising from delocalization of either a syn or an anti lone pair, and with no detectable angle-independent inductive effect.
- Perrin, Charles L.,Ohta, Brian K.,Kuperman, Joshua,Liberman, Jordan,Erdelyi, Mate
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p. 9641 - 9647
(2007/10/03)
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- Diastereoselective Synthesis of Cis-3- And 3,5-Alkylpyrrolizidines
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Cis-3 and 3,5-substituted pyrrolizidines can be prepared from β-enaminolactones. Substituted pyrrolidinoketones lead to these compounds by an amino reductive annelation with a low diastereomeric excess, but a best access to these azabicycles consists in preparing cis-2,5-disubstituted pyrrolidines which are then transformed into the expected heterocycles.
- Provot, Olivier,Celerier, Jean-Pierre,Lhommet, Gerard
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p. 371 - 376
(2007/10/03)
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- Synthesis of azetidine, pyrrolidines and piperidine by intramolecular cyclization of ω-Azidoboranes.
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This paper describes the development of efficient routes to azetidine, pyrrolidines and piperidines by creation of a carbon-nitrogen bond.Two complementary syntheses of these heterocycles were studied : the cyclization of ω-azidoboronic esters by treatment with boron trichloride, and the one pot hydroboration of an ω-azidoalkene and intramolecular reductive alkylation.The scope and limitations of these two promising approaches are reported.Keywords: azides / boronic esters / boranes / intermolecular cyclization / azetidine / pyrrolidine / piperidine / pyrrolizidine
- Jego, J. M.,Carboni, B.,Vaultier, M.
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p. 554 - 565
(2007/10/02)
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- N-hydroxypyridine-2-thione carbamates. V. Syntheses of alkaloid skeletons by aminium cation radical cyclizations
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The title radical precursors (PTOC carbamates) were employed as sources of a variety of 5,6-unsaturated aminium cation radicals. 5-Exo radical cyclization followed by trapping by t-BuSH or the PTOC carbamate gave a variety of aklaloid skeletons, typically in good to excellent yields, including pyrrolidines, perhydroindoles, pyrrolizidines, tropanes, 9-azabicyclo[4.2.1]nonanes, 6-azabicyclo [3.2.1]octanes. 6-Exo and 7-endo cyclizations competed in a 6,7-unsaturated system.
- Newcomb, Martin,Marquardt, Donald J.,Deeb, Thomas M.
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p. 2329 - 2344
(2007/10/02)
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- Bicyclization of aza-compounds by positive halide ions. I. Cyclic amines
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Cyclic amines are oxidized to the bicyclic compounds by electrochemical oxidation.The presence of halide ions is found necessary for the reaction to proceed and to produce any bicyclic products.It is postulated that a positive halide species, X(+), is produced electrochemically and stabilized under the specific reaction conditions.The X(+) ion forms a complex with the parent cyclic amine which decomposes to the bicyclic product and HX.An analogy between the Hofer-Moest reaction to produce C(+) and this reaction to produce X(+) is postulated.
- Elofson, R. M.,Gadallah, F. F.,Laidler, J. K.
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p. 1170 - 1172
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF 1-AZABICYCLOALKANES AND THEIR LACTAMS VIA CUPRATES OF FORMAMIDINES
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Piperidine and pyrrolidine formamidines, transformed into their α-metalloderivatives are alkylated with bifunctional electrophiles and cyclized, on formamidine removal, to the title compounds.
- Edwards, Philip D.,Meyers, A. I.
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p. 939 - 942
(2007/10/02)
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- Hydroboration-Carbon Monoxide Insertion of Bis-Olefinic Amine Derivatives. Synthesis of δ-Coniceine, Pyrrolizidine, (+/-)-Heliotridane, and (+/-)-Pseudoheliotridane
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The hydroboration-carbon monoxide insertion of several bis-olefinic derivatives has provided facile preparations of N-(carbomethoxy)-5-azacyclooctanone (6), N-(carbobenzyloxy)-5-azacyclooctanone (9), and N-(carbobenzyloxy)-5-cyclononanone (18).Of the hydroboration protocols examined, thexylborane-cyanidation proved to be the most useful.Reductive ring closure of 9 and of 18 gave 26 and 27, respectively.Methylation of 9 followed by reduction afforded 29 and 30.
- Garst, Michael E.,Bonfiglio, John N,Marks, Jeffrey
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p. 1494 - 1500
(2007/10/02)
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- Silver Ion Induced Rearrangement of N-Chloramines. Isolation of an Ionic Product in High Yield
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Treatment of N-chlorogranatanine with silver tetrafluoroborate in benzene followed by hydride reduction provides δ-coniceine in high yield. Similarly, N-chloro derivatives of nortropane and trans-decahydroquinoline provided pyrrolizidine and 1-azabicyclodecane, respectively. Under these reaction conditions, only small amounts of secondary amines are found in the product. The rearrangement product of N-chlorogranatanine was isolated without hydride reduction and shown to be the expected immonium ion product.
- Schell, Fred M.,Ganguly, Rathindra N.
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p. 4069 - 4070
(2007/10/02)
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