Synergistic Ammonium (Hypo)Iodite/Imine Catalysis for the Asymmetric α-Hydroxylation of β-Ketoesters
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چکیده
منابع مشابه
Towards an asymmetric organocatalytic α-cyanation of β-ketoesters
This communication describes the first proof of concept for an asymmetric α-cyanation of β-ketoesters using a hypervalent iodine-based electrophilic cyanide-transfer reagent. A series of different organocatalysts has been investigated and it was found that the use of naturally occurring Cinchona alkaloids allows obtaining the target products in good yields and with moderate enantioselectivities...
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Systematic studies of reaction conditions and subsequent optimization led to the identification of important parameters for stereoselectivity in the asymmetric alpha-hydroxylation reaction of 1,3-ketoesters. Enantioselectivities of up to 98% can be achieved for cyclic substrates and 88% for acyclic ketoesters. Subsequently, the combination of cyclic/acyclic ketoester, catalyst, and oxidant was ...
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A new general concept for α,β-unsaturated acyl ammonium catalysis is reported that uses p-nitrophenoxide release from an α,β-unsaturated p-nitrophenyl ester substrate to facilitate catalyst turnover. This method was used for the enantioselective isothiourea-catalyzed Michael addition of nitroalkanes to α,β-unsaturated p-nitrophenyl esters in generally good yield and with excellent enantioselect...
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The copper-catalyzed α-amination of carbonyl compounds using nitrosoformate intermediates as the electrophilic source of nitrogen is reported. The reaction merges aerobic oxidation and Lewis acid catalysis. The scope of the reaction is broad in terms of both the N-substituted hydroxylamines and the β-ketoesters. The new methodology harnesses the power of nitrosoformate intermediates and demonst...
متن کاملSynthesis of optically active dihydropyrans from asymmetric [4 + 2] cycloaddition of β,γ-unsaturated α-ketoesters with allenic esters.
β-Isocupreidine (β-ICD) catalyzed asymmetric [4 + 2] cycloaddition of β,γ-unsaturated α-ketoesters with allenic esters afforded ester-substituted functionalized dihydropyran derivatives in high yields along with high enantioselectivities under mild conditions.
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ژورنال
عنوان ژورنال: Organic Letters
سال: 2020
ISSN: 1523-7060,1523-7052
DOI: 10.1021/acs.orglett.0c02198