Cooperative Lewis acid/N-heterocyclic carbene catalysis
نویسندگان
چکیده
منابع مشابه
Oxidative γ-addition of enals to trifluoromethyl ketones: enantioselectivity control via Lewis acid/N-heterocyclic carbene cooperative catalysis.
An oxidative γ-functionalization of enals under N-heterocyclic carbene (NHC) catalysis to give unsaturated δ-lactones is disclosed. Enantioselectivity control involving the relatively remote enal γ-carbon was achieved via Lewis acid [Sc(OTf)(3) or combined Sc(OTf)(3)/Mg(OTf)(2)] and NHC cooperative catalysis.
متن کاملChiral N-heterocyclic carbene/Lewis acid cooperative catalysis of the reaction of 2-aroylvinylcinnamaldehydes: a switch of the reaction pathway by Lewis acid activation.
The chiral N-heterocyclic carbene/Lewis acid co-catalyzed reaction of 2-aroylvinylcinnamaldehydes produced good yields of indeno[1,2-c]furan-1-one derivatives with excellent enantioselectivity and diastereoselectivity. A switch of intramolecular cyclization to intermolecular dimerization was achieved by the cooperative catalysis of chiral triazole carbene and Ti(OPr-i)4 catalysts.
متن کاملN-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis
The interplay between metals and N-heterocyclic carbenes (NHCs) has provided a window of opportunities for the development of novel catalytic strategies within the past few years. The recent successful combination of Brønsted acids with NHCs has added a new dimension to the field of cooperative catalysis, enabling the stereoselective synthesis of functionalized pyrrolidin-2-ones as valuable sca...
متن کاملFrustrated N-heterocyclic carbene-silylium ion Lewis pairs.
The reaction of the N-heterocyclic carbene 1,3-di-tert-butyl-4,5-dimethylimidazolin-2-ylidene () with trimethylsilyl iodide, triflate and triflimidate [Me3SiX, X = I, CF3SO3 (OTf), (CF3SO2)2N (NTf2)] by mixing the neat, liquid starting materials afforded the corresponding 2-(trimethylsilyl)imidazolium salts [()SiMe3]X as highly reactive, white crystalline solids. Only the triflimidate (X = NTf2...
متن کاملEnantioselective cyclopropanation of enals by oxidative N-heterocyclic carbene catalysis.
Carbene catalysed redox activation of α,β-unsaturated aldehydes is applied for generation of α,β-unsaturated acyl azoliums which undergo cyclopropanation upon reaction with a sulfur ylide and an alcohol to give the corresponding cyclopropanecarboxylic acid esters. With chiral carbenes good to excellent diastereo and enantioselectivities are obtained.
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ژورنال
عنوان ژورنال: Chem. Sci.
سال: 2012
ISSN: 2041-6520,2041-6539
DOI: 10.1039/c1sc00621e