- Photoaddition of ketene silyl acetals to electron-deficient arylakenes via single electron transfer
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Photoreaction of 1-cyano-2-phenylethene and 1,1-dicyano-2-phenylethene with β,β-dialkyl-substituted ketene silyl acetals in acetonitrile in the presence of aromatic hydrocarbon as a photosensitizer regioselectively afforded alkylated products in high yields.
- Mizuno, Kazuhiko,Takahashi, Naoki,Nishiyama, Toshinori,Inoue, Hiroo
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- Hydrogen-Bonding Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers over Ionic Liquid under Metal-Free Conditions
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O-heterocycles have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen-bonding catalyzed ring-closing metathesis of aliphatic ethers to O-heterocycles over ionic liquid (IL) catalyst under metal- and solvent-free conditions. The IL 1-butylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([SO3H-BMIm][OTf]) is discovered to show outstanding performance, better than the reported catalysts. An interface effect plays an important role in mediating the reaction rate due to the immiscibility between the products and the IL catalyst, and the products can be spontaneously separated. NMR analysis and DFT calculation suggest that a pair of cation and anion of [SO3H-BMIm][OTf] could form three strong H-bonds with an ether molecule, which catalyze the ether transformation via a cyclic oxonium intermediate. A series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines and dioxane can be obtained from their corresponding ethers in excellent yields (e.g., >99 %). This work opens an efficient and metal-free way to produce O-heterocycles from aliphatic ethers.
- Wang, Huan,Zhao, Yanfei,Zhang, Fengtao,Wu, Yunyan,Li, Ruipeng,Xiang, Junfeng,Wang, Zhenpeng,Han, Buxing,Liu, Zhimin
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supporting information
p. 11850 - 11855
(2020/05/16)
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- Scalable and Highly Diastereo- and Enantioselective Catalytic Diels-Alder Reaction of α,β-Unsaturated Methyl Esters
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Despite tremendous advances in enantioselective catalysis of the Diels-Alder reaction, the use of simple α,β-unsaturated esters, one of the most abundant and useful class of dienophiles, is still severely limited in scope due to their low reactivity. We report here a catalytic asymmetric Diels-Alder methodology for a large variety of α,β-unsaturated methyl esters and different dienes based on extremely reactive silylium imidodiphosphorimidate (IDPi) Lewis acids. Mechanistic insights from accurate domain-based local pair natural orbital coupled-cluster (DLPNO-CCSD(T)) calculations rationalize the catalyst control and stereochemical outcome.
- Gatzenmeier, Tim,Turberg, Mathias,Yepes, Diana,Xie, Youwei,Neese, Frank,Bistoni, Giovanni,List, Benjamin
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supporting information
p. 12671 - 12676
(2018/10/15)
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- The Catalytic Asymmetric Mukaiyama–Michael Reaction of Silyl Ketene Acetals with α,β-Unsaturated Methyl Esters
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α,β-Unsaturated esters are readily available but challenging substrates to activate in asymmetric catalysis. We now describe an efficient, general, and highly enantioselective Mukaiyama–Michael reaction of silyl ketene acetals with α,β-unsaturated methyl esters that is catalyzed by a silylium imidodiphosphorimidate (IDPi) Lewis acid.
- Gatzenmeier, Tim,Kaib, Philip S. J.,Lingnau, Julia B.,Goddard, Richard,List, Benjamin
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supporting information
p. 2464 - 2468
(2018/02/06)
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- First sequential Mukaiyama-Michael reaction/crossed-Claisen condensation using two molar ketene silyl acetals and one molar α,β-unsaturated esters promoted by a NaOH catalyst
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The NaOH-catalyzed first sequential Mukaiyama-Michael reaction/crossed- Claisen condensation is developed using two molar ketene silyl acetals and one molar α,β-unsaturated esters in either a stepwise or one-pot manner.
- Tamagaki, Hiroaki,Nawate, Yuuya,Nagase, Ryohei,Tanabe, Yoo
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supporting information; experimental part
p. 5930 - 5932
(2010/10/21)
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- The Michael Reaction of O-Silylated Ketene Acetals with α,β-Unsaturated Esters Promoted by a Catalytic Amount of Aluminium Triflate
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The Michael reaction of O-silylated ketene acetals with α,β-unsaturated ester in the presence of a catalytic amount of aluminium triflate proceeds smoothly under mild conditions to afford the corresponding glutarates in good yields.
- Minowa, Nobuto,Mukaiyama, Teruaki
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p. 1719 - 1722
(2007/10/02)
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