- Preparation of 2-azaallyl anions and imines from N-chloroamines and their cycloaddition and allylation
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Exposure of N-chloroamines to KOtBu or LDA, in the presence of PMDETA or HMPA, provides 2-azaallyl anions capable of π4s + π2s cycloaddition reactions with a range of olefins. Good yields were achieved with stabilised systems, however, they were more modest when accessing semi-stabilised 2-azaallyl anions. By modifying the reaction conditions, one-pot dehydrochlorination/allylation can also be achieved with a range of N-chloroamines.
- Pandiancherri, Shveta,Lupton, David W.
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p. 671 - 674
(2011/03/22)
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- Imino-ene reaction of N-tosyl arylaldimines with α-methylstyrene: Application in the synthesis of important amines
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Copper(II) or tin(II) trifluoromethanesulfonate in combination with TMSCl effectively activates a C-H bond for the imino-ene reaction of N-tosylarylaldimines with α-methylstyrene. A wide variety of N-tosylarylaldimines were used to give homoallylamines in
- Pandey, Manoj K.,Bisai, Alakesh,Pandey, Ankur,Singh, Vinod K.
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p. 5039 - 5041
(2007/10/03)
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- Generation of 2-azaallyl anions by the transmetalation of N-(trialkylstannyl)methanimines. Pyrrolidine synthesis by [3 + 2] cycloadditions with alkenes
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Treatment of N-(trimethylstannyl)methanimines or N-(tri-n-butylstannyl)methanimines with methyllithium or n-butyllithium, respectively, affords 2-azaallyl anions by tin-lithium exchange. These anions undergo intermolecular or intramolecular [π4s + π2s] cycloadditions with alkenes and alkynes to generate pyrrolidines or pyrrolines after quenching with water or other electrophiles. The tin-lithium exchange method allows unstabilized 2-azaallyl anions to be generated for the first time. The lifetime of the anions is limited by a competing intermolecular side reaction. Therefore, relatively reactive alkenes and alkynes must be used, such as stilbene, styrenes, enynes, diphenylacetylene, vinyl sulfides, vinyl selenides, and vinyl silanes. The latter three types of anionophiles afford functionalized cycloadducts which may be transformed into more useful pyrrolidines by reduction, elimination, or oxidation. A synthesis of the alkaloid (±)-mesembrane was accomplished using an intramolecular 2-azaallyl anion cycloaddition.
- Pearson, William H.,Szura, Daniel P.,Postich, Michael J.
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p. 1329 - 1345
(2007/10/02)
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- TRANSMETALLATION OF N-(TRIALKYLSTANNYL)METHYLIMINES. A NEW METHOD FOR THE GENERATION AND CYCLOADDITION OF 2-AZAALLYL ANIONS.
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Transmetallation of imines 1 at -78 deg C with RLi provided 2-azaallyl anions 2, which readily undergo cycloaddition with olefinic anionophiles, providing pyrrolidines.Of particular note is the generation of unstabilized 2-azaallyl anions for the first ti
- Pearson, William H.,Szura, Daniel P.,Harter, William G.
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p. 761 - 764
(2007/10/02)
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- Synthetic Versatility of N(Silylmethyl)imines: Water-Induced Generation of N-Protonated Azomethine Ylides of Nonstabilized Type and Fluoride-Induced Generation of 2-Azallyl Anions
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N-(Silylmethyl)imines generate N-protonated azomethine ylides of nonstabilized type when treated with water in HMPA, which undergo stereospecific and regioselective cycloadditions with electron-poor olefins affording N-unsubstituted pyrrolidines.On the other hand, fluoride-induced desilylation of the imines leads to 2-azallyl anions which are found to be synthetic equivalents of aminomethyl anion in the Michael additions with electron-poor olefins and nucleophilic additions with carbonyl compounds.
- Tsuge, Otohiko,Kanemasa, Shuji,Hatada, Akira,Matsuda, Koyo
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p. 2537 - 2546
(2007/10/02)
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- Reduction electrochimique de γ-nitrocetones. Conditions experimentales d'acces a des derives de la pyrroline et de la pirrolidine
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Optimal conditions for electrosynthesis, at a mercury cathode in hydroalcoholic media, of three classes of nitrogen heterocyclic compounds are set up from an exhaustive study of the electrochemical behaviour of γ-nitroketones 1 and their reduction product
- Cariou, Michel,Hazard, Roland,Jubault, Michel,Tallec, Andre
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p. 2359 - 2366
(2007/10/02)
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