- Visible-Light-Driven, Metal-Free Divergent Difunctionalization of Alkenes Using Alkyl Formates
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In recent decades, difunctionalization of alkenes has received considerable attention as an efficient and straightforward way to increase molecular complexity. However, examples of the difunctionalization of alkenes initiated by the intermolecular addition of alkoxycarbonyl radicals providing substituted alkanoates are still rare. Herein, we present the visible light-driven metal-free divergent difunctionalization of alkenes triggered by the intermolecular addition of alkoxycarbonyl radicals under ambient conditions. Employing alkyl formates as precursors of alkoxycarbonyl radicals and 4CzIPN as the photocatalyst, a variety of substituted alkanoates, including β-alkoxy, β-hydroxy, β-dimethoxymethoxy, and β-formyloxy alkanoates, could be facilely accessed with high functional group tolerance and high efficiency. Moreover, the mechanism study revealed that β-hydroxy alkanoates were generated by a selective decomposition of orthoformates promoted by the N-alkoxyazinium salt.
- Zheng, Ming,Hou, Jing,Zhan, Le-Wu,Huang, Yan,Chen, Ling,Hua, Li-Li,Li, Yan,Tang, Wan-Ying,Li, Bin-Dong
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p. 542 - 553
(2021/01/14)
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- One-pot enol silane formation-Mukaiyama aldol reactions: Crossed aldehyde-aldehyde coupling, thioester substrates, and reactions in ester solvents
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Trimethylsilyl trifluoromethanesulfonate (TMSOTf) and a trialkylamine base promote both in situ enol silane/silyl ketene acetal formation and Mukaiyama aldol addition reactions between a variety of reaction partners in a single reaction flask. Isolation of the required enol silane or silyl ketene acetal is not necessary. For example, crossed aldol reactions between α-disubstituted aldehydes and non-enolizable aldehydes yield β-hydroxy aldehydes in good yield. In a related reaction, the common laboratory solvent ethyl acetate functions as both an enolate precursor and a green reaction solvent. When thioesters are employed as enolate precursors, high yields for additions to non-enolizable aldehydes are routinely observed.
- Downey, C. Wade,Dixon, Grant J.,Ingersoll, Jared A.,Fuller, Claire N.,MacCormac, Kenneth W.,Takashima, Anna,Sediqui, Rohina
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supporting information
(2019/10/14)
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- A tandem enol silane formation-Mukaiyama aldol reaction mediated by TMSOTf
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A slight excess of silyl trifluoromethanesulfonate mediates a tandem enol silane formation-Mukaiyama aldol reaction in the presence of Hunig's base. Preformation of the enol silane is unnecessary for efficient reactions, which proceed in 75-97% yield for the addition of aryl methyl ketones and acetate esters to non-enolizable aldehydes. Mechanistic data suggests that free amine is crucial for full conversion.
- Downey, C. Wade,Johnson, Miles W.
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p. 3559 - 3562
(2007/10/03)
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- Candida Rugosa lipase-catalyzed kinetic resolution of β-hydroxy- β-arylpropionates and δ-hydroxy-δ-aryl-β-oxo-pentanoates
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A simple and convenient method was reported for the preparation of optically active β-hydroxy-β-arylpropionates, δ-hydroxy-δ- aryl-β-oxo-pentanoates and their butyryl derivatives via CRL-catalyzed hydrolysis. The optically active products are potential precursors of some chiral pharmaceuticals and natural products.
- Xu, Chengfu,Yuan, Chengye
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p. 2169 - 2186
(2007/10/03)
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- A general method for the formation of zinc enolate equivalents from iodoacetates by diisopropylzinc-iodine exchange reaction: Preparation of β-Hydroxy esters
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Diisopropylzinc is found to be a highly efficient reagent for the formation of zinc enolate equivalents from various iodoacetates via iodine-Zinc exchange reaction at room temperature, affording β-Hydroxy esters in high yields by the reaction with aldehydes and ketones.
- Sato,Takizawa,Soai
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p. 2825 - 2826
(2007/10/03)
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