- Copper-catalyzed ring-opening reactions of alkyl aziridines with b2 pin2: Experimental and computational studies
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The possibility to form new C–B bonds with aziridines using diboron derivatives con-tinues to be a particularly challenging field in view of the direct preparation of functionalized β-aminoboronates, which are important compounds in drug discovery, being a bioisostere of β-aminoacids. We now report experimental and computational data that allows the individua-tion of the structural requisites and of reaction conditions necessary to open alkyl aziridines using bis(pinacolate)diboron (B2 pin2 ) in a regioselective nucleophilic addition reaction under copper catalysis.
- Boldrini, Cosimo,Comparini, Lucrezia Margherita,Di Bussolo, Valeria,Di Pietro, Sebastiano,Favero, Lucilla,Menichetti, Andrea,Pineschi, Mauro
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supporting information
(2021/12/17)
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- Activation of carboxylic acids in asymmetric organocatalysis
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Organocatalysis, catalysis using small organic molecules, has recently evolved into a general approach for asymmetric synthesis, complementing both metal catalysis and biocatalysis.1 Its success relies to a large extent upon the introduction of novel and generic activation modes.2 Remarkably though, while carboxylic acids have been used as catalyst directing groups in supramolecular transition-metal catalysis,3 a general and well-defined activation mode for this useful and abundant substance class is still lacking. Herein we propose the heterodimeric association of carboxylic acids with chiral phosphoric acid catalysts as a new activation principle for organocatalysis. This self-assembly increases both the acidity of the phosphoric acid catalyst and the reactivity of the carboxylic acid. To illustrate this principle, we apply our concept in a general and highly enantioselective catalytic aziridine-opening reaction with carboxylic acids as nucleophiles. Activation by dimerization: There is still no general activation mode for carboxylic acids in organocatalysis. The formation of heterodimers between chiral phosphoric acid diesters and carboxylic acids can be used to activate and direct reactivity of the latter in asymmetric reactions. This novel principle has been applied to the ring-opening desymmetrization and kinetic resolution of aziridines leading to valuable amino alcohols.
- Monaco, Mattia Riccardo,Poladura, Belen,Diaz De Los Bernardos, Miriam,Leutzsch, Markus,Goddard, Richard,List, Benjamin
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p. 7063 - 7067
(2014/07/08)
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- Scalable synthesis of N -acylaziridines from N -tosylaziridines
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N-Acylaziridines are important starting materials for the synthesis of chiral amine derivatives. The traditional methods for producing these activated aziridines have significant drawbacks. The gram scale synthesis of N-acylaziridines by deprotection of N
- Rubin, Heather,Cockrell, Jennifer,Morgan, Jeremy B.
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p. 8865 - 8871
(2013/09/24)
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- Enantioselective synthesis and stereoselective ring opening of N-acylaziridines
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Kinetic resolution of N-acylaziridines by nucleophilic ring opening was achieved with (R)-BINOL as the chiral modifier under boron-catalyzed conditions (see scheme; Ar=3,5-dinitrophenyl). The consumed enantiomer of aziridine can be further converted to an enantioenriched 1,2-chloroamide with recovery of (R)-BINOL. Copyright
- Cockrell, Jennifer,Wilhelmsen, Christopher,Rubin, Heather,Martin, Allen,Morgan, Jeremy B.
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supporting information
p. 9842 - 9845
(2012/11/07)
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- Phosphine-catalyzed heine reaction
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Aziridines are important synthetic intermediates which readily undergo ring-opening reactions. It is demonstrated that electron-rich phosphines are efficient catalysts for the regioselective rearrangement of N-acylaziridines to oxazolines. The reactions o
- Martin, Allen,Casto, Kathleen,Morris, William,Morgan, Jeremy B.
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p. 5444 - 5447
(2011/12/05)
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