- Lewis Acid Regulated Divergent Catalytic Reaction between Quinone Imine Ketals (QIKs) and 1,3-Dicarbonyl Compounds: Switchable Access to Multiple Products Including 2-Aryl-1,3-Dicarbonyl Compounds, Indoles, and Benzofurans
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A catalytic Lewis acid regulated reaction between quinone imine ketals (QIKs) and 1,3-dicarbonyl compounds provides a divergent and tunable approach to a variety of skeletons, including a series of 2-aryl-1,3-dicarbonyl compounds, indoles, and benzofurans. The use of lithium chloride and ferrous bromide gives C3- or C2-alkylation products of the QIKs. The combination of ferrous bromide and trifluoromethanesulfonic acid delivers indole derivatives. Sequential hydrolysis and C3-alkylation occur in the presence of ytterbium (III) trifluoromethanesulfonate and stoichiometric amounts of water. When the reaction is performed with trifluoromethanesulfonic acid and stoichiometric amounts of water, benzofuran is obtained. This protocol utilizes mild conditions, exhibits regio- and chemoselectivity, and has broad functional group tolerance. (Figure presented.).
- Chen, Xingyu,Lu, Sixian,Deng, Ping,Chang, Xiaoqiang,Zhao, Yifan,Ma, Yue,Zhang, Dong,Xia, Fei,Yang, Lan,Wang, Jigang,Sun, Peng
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supporting information
p. 94 - 102
(2021/10/05)
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- Amide/Ester Cross-Coupling via C-N/C-H Bond Cleavage: Synthesis of β-Ketoesters
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Activated primary, secondary, and tertiary amides were coupled with enolizable esters in the presence of LiHMDS to obtain good yields of β-ketoesters at room temperature. Notably, this protocol provides an efficient, mild, and high chemoselectivity method
- Chen, Jiajia,Joseph, Devaneyan,Xia, Yuanzhi,Lee, Sunwoo
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p. 5943 - 5953
(2021/04/02)
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- Photoredox Catalysis of Aromatic β-Ketoesters for in Situ Production of Transient and Persistent Radicals for Organic Transformation
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Radical formation is the initial step for conventional radical chemistry. Reported herein is a unified strategy to generate radicals in situ from aromatic β-ketoesters by using a photocatalyst. Under visible-light irradiation, a small amount of photocatalyst fac-Ir(ppy)3 generates a transient α-carbonyl radical and persistent ketyl radical in situ. In contrast to the well-established approaches, neither stoichiometric external oxidant nor reductant is required for this reaction. The synthetic utility is demonstrated by pinacol coupling of ketyl radicals and benzannulation of α-carbonyl radicals with alkynes to give a series of highly substituted 1-naphthols in good to excellent yields. The readily available photocatalyst, mild reaction conditions, broad substrate scope, and high functional-group tolerance make this reaction a useful synthetic tool.
- Chen, Bin,Feng, Ke,Guo, Jia-Dong,Tung, Chen-Ho,Wu, Li-Zhu,Xiao, Hongyan,Yang, Xiu-Long
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supporting information
p. 5365 - 5370
(2020/02/28)
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- PhIO/Et3N ? 3HF-Mediated Formation of Fluorinated 2H-Azirines via Domino Fluorination/Azirination Reaction of Enamines
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A variety of enamine carboxylic esters and enaminones were converted to the biologically interesting fluorinated 2H-azirines through reactions with PhIF2 generated in situ by PhIO and Et3N ? 3HF in 1,2-dichroloethane, which features the hypervalent iodine reagents-mediated introduction of fluorine atom and formation of the 2H-azirine skeleton under metal-free conditions. The domino reaction is postulated to proceed via a PhIF2-mediated oxidative fluorination and a subsequent azirination of the fluorinated enamine intermediates. (Figure presented.).
- Zhang, Yong,Zhao, Xiaoyuan,Zhuang, Chen,Wang, Senlin,Zhang-Negrerie, Daisy,Du, Yunfei
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p. 2107 - 2112
(2018/04/19)
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- Mechanochemical electrophilic fluorination of liquid beta-ketoesters
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An improved substrate scope for the mechanochemical electrophilic fluorination of dicarbonyls is reported. The applicable substrates have now been broadened to include liquid β-ketoesters. Key to this capability is the inclusion of a grinding auxiliary (NaCl) to improve mass transfer and prevent pasting or gumming of the reaction mixture. Notably, the use of a small amount of acetonitrile is critical to increasing the rate of reaction, ensuring complete consumption of starting materials during the short reaction times as well as improving the selectivity for the monofluorinated product in the mill.
- Howard, Joseph L.,Sagatov, Yerbol,Browne, Duncan L.
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p. 3118 - 3123
(2017/12/26)
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- Metal-free intermolecular cyclopropanation between alkenes and iodonium ylides mediated by PhI(OAc)2·Bu4NI
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A rapid, mild and metal-free intermolecular cyclopropanation between iodonium ylides and alkene-containing substrates mediated by PhI(OAc)2·Bu4NI is reported. Iodonium ylides of cyclic and acyclic 1,3-dicarbonyls were reacted with a variety of mono-, di-, tri- and tetra-substituted alkenes of various structural types to give 29 cyclopropanes in up to 97% yield.
- Tao, Jason,Estrada, Carl D.,Murphy, Graham K.
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supporting information
p. 9004 - 9007
(2017/08/15)
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- Selective α-amination and α-acylation of esters and amides via dual reactivity of O-acylhydroxylamines toward zinc enolates
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Selective α-amination and α-acylation of esters and amides have been developed, employing O-acylhydroxylamines as a dually reactive aminating and acylating reagent. Treatment of zinc enolates with O-acylhydroxylamines provides solely 1,3-dicarbonyl compounds under mild conditions. Introduction of a copper catalyst into the system shifts the reactivity entirely, yielding α-amination products exclusively.
- McDonald, Stacey L.,Wang, Qiu
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supporting information
p. 2535 - 2538
(2014/03/21)
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- Primary β-amino acid salt-catalyzed asymmetric Michael addition of benzoylacetates to cyclic enones and its application for the synthesis of enantioenriched 1,5-diketones
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The asymmetric Michael addition of benzoylacetates to cyclic enones was successfully carried out by using a primary β-amino acid salt catalyst. The reactions proceeded under mild reaction conditions to produce Michael adducts in high yields and with high enantioselectivities. The obtained Michael adducts were converted into β-benzoylmethylated cyclic ketones by decarboxylation without a significant loss of enantiomeric excess.
- Yoshida, Masanori,Kubara, Ami,Hara, Shoji
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p. 180 - 182
(2013/03/28)
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- A new method for the regioselective synthesis of β-enamino acid derivatives
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A mild, simple and efficient route to β-enamino imidazole carbonilic derivatives 3 by reaction of ketimines with N,N′-carbonyl diimidazole in the presence of boron triflouride as catalyst has been developed. The conversion of 3 to esters has also been explored.
- Fustero, Santos,Diaz, Ma. Dolores,Carlon, Raquel Perez
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p. 725 - 728
(2007/10/02)
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- ACYLATION OF ACTIVE METHYLENE COMPOUNDS VIA PALLADIUM COMPLEX-CATALYZED CARBONYLATIVE CROSS-COUPLING OF ORGANIC HALIDES
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New procedures for acylation of active methylene compounds via palladium complex-catalyzed carbonylation of organic halides are disclosed.
- Kobayashi, Toshi-aki,Tanaka, Masato
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p. 4745 - 4748
(2007/10/02)
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