Topic
Alkylation
About: Alkylation is a research topic. Over the lifetime, 29915 publications have been published within this topic receiving 464944 citations. The topic is also known as: alkylation reaction.
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TL;DR: In this paper, the authors investigated the nonlinear properties of the asymmetric reaction of dimethylzinc and benzaldehyde in the presence of (2S)-3-exo-(dimethylamino)isoborneol [(2S]-DAIB] and showed that the enantiomeric purity of the product is much higher than that of the chiral source, DAIB, while the rate of enantioselective catalysis decreases considerably.
Abstract: Asymmetric reaction of dimethylzinc and benzaldehyde in the presence of (2S)-3-exo-(dimethylamino)isoborneol [(2S)-DAIB] exhibits unusual nonlinear phenomena. The enantiomeric purity of the product is much higher than that of the chiral source, DAIB, while the rate of the enantioselective catalysis decreases considerably as the enantiomeric excess (ee) of DAIB is lowered. Such effects originate from the reversible homochiral and heterochiral interaction of the coexistent enantiomeric zinc amino alkoxide catalysts which are formed from dimethylzinc and (2S)- and (2R)-DAIB. The thermodynamics of the five-component equilibration between the two monomers and three dimers, when coupled with the kinetics of the alkylation, strongly affects the extent of enantioselectivity and the reaction rate of the alkylation reaction. The overall profile of the nonlinear effects has been clarified mathematically using experimentally available parameters, viz., the equilibrium constants of the dimer/monomer conversion and the...
190 citations
TL;DR: The first successful Pd-catalyzed intramolecular ipso-Friedel-Crafts allylic alkylation of phenols, which provided a new access to spiro[4.5]cyclohexadienones, is described.
189 citations
TL;DR: This work presents the first examples of Cu-catalyzed enantioselective conjugate additions of alkyl- and arylzinc reagents to unactivated cyclic beta-substituted enones, affording the desired products bearing all-carbon quaternary stereogenic centers in 67-->98% yield and in up to 97% ee.
Abstract: We present the first examples of Cu-catalyzed enantioselective conjugate additions of alkyl- and arylzinc reagents to unactivated cyclic beta-substituted enones. Transformations are promoted in the presence of 2.5-15 mol % of a readily available chiral NHC-based Cu complex, affording the desired products bearing all-carbon quaternary stereogenic centers in 67-->98% yield and in up to 97% ee. Catalytic enantioselective reactions can be carried out on a benchtop, with undistilled solvent and commercially available (not further purified) Cu salts. Mechanistic models, accounting for the observed levels and trends in enantioselectivity are provided.
188 citations
TL;DR: A phosphoric acid derived from H8-BINOL enabled an asymmetric alpha-alkylation of enamides with indolyl alcohols to give beta-aryl 3-(3-indolyl)propanones in high yields and with excellent enantioselectivity.
188 citations
188 citations