- Directed ortho-Metalation of O-Aryl N,N-Dialkylcarbamates: Methodology, Anionic ortho-Fries Rearrangement, and Lateral Metalation
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The directed ortho-lithiation reactions of O-aryl N,N-dialkylcarbamates as well as O-1-naphthyl and O-2-naphthyl N,N-dialkylcarbamates with sec-butyllithium/tetramethylethylenediamine (sBuLi/TMEDA) followed by quenching with various electrophiles afford a range of polysubstituted aromatic compounds. If the solutions of the ortho-lithiated carbamates are warmed to room temperature without the addition of external electrophiles, salicylamide and 1- and 2-hydroxynaphthamide derivatives are formed through anionic ortho-Fries rearrangements. The relative stabilities and reactivities of different O-aryl N,N-dialkylcarbamates were investigated. The lateral metalation of 2-tolyl carbamates with lithium diisopropylamide (LDA) provides a route to benzo[b]furan-2(3H)-ones. Previously reported results are used in a comparison of seven O-based directed metalation groups in reactions with several electrophiles. The described methodology is useful for the preparation of 1,2,3-substituted aromatic compounds.
- Miah, M. A. Jalil,Sibi, Mukund P.,Chattopadhyay,Familoni, Oluwole B.,Snieckus, Victor
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p. 440 - 446
(2017/12/15)
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- Pd(II) catalyzed ortho C-H iodination of phenylcarbamates at room temperature using cyclic hypervalent iodine reagents
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A novel approach to access ortho iodinated phenols using cyclic hypervalent iodine reagents through palladium(II) catalyzed C-H activation has been developed through weak coordination. The reaction showed excellent regioselectivity, reactivity and good functional group tolerance. A unique mechanism was proposed.
- Sun, Xiuyun,Yao, Xia,Zhang, Chao,Rao, Yu
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supporting information
p. 10014 - 10017
(2015/06/22)
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- Room-temperature Pd-catalyzed C-H chlorination by weak coordination: One-pot synthesis of 2-chlorophenols with excellent regioselectivity
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A room-temperature Pd(ii)-catalyzed regioselective chlorination reaction has been developed for a facile one-pot synthesis of a broad range of 2-chlorophenols. The reaction demonstrates an excellent regioselectivity and reactivity for C-H chlorination. This reaction represents one of the rare examples of mild C-H functionalization at ambient temperature.
- Sun, Xiuyun,Sun, Yonghui,Zhang, Chao,Rao, Yu
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supporting information
p. 1262 - 1264
(2014/02/14)
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- A general approach towards catechol and pyrogallol through ruthenium- and palladium-catalyzed C-H hydroxylation by weak coordination
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An efficient ruthenium(II)- and palladium(II)-catalyzed C-H hydroxylation of aryl carbamates has been developed for the facile synthesis of catechols and pyrogallols. The reaction demonstrates excellent reactivity, regio- and chemoselectivity, good functional group compatibility and high yields. The practicality of this method has been proved by a gram-scale synthesis.
- Yang, Xinglin,Sun, Yonghui,Chen, Zhang,Rao, Yu
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supporting information
p. 1625 - 1630
(2014/06/09)
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- A copper metal-organic framework as an efficient and recyclable catalyst for the oxidative cross-dehydrogenative coupling of phenols and formamides
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A crystalline porous metal-organic framework Cu2(BPDC)2(BPY) (BPDC=4,4'-biphenyldicarboxylate, BPY=4,4'-bipyridine) was synthesized and characterized by several techniques including XRD, SEM, TEM, thermogravimetric analysis, FTIR, atomic absorption spectrophotometry, hydrogen temperature-programmed reduction, and nitrogen physisorption measurements. The Cu2(BPDC)2(BPY) could be employed as a heterogeneous catalyst for the copper-catalyzed cross-dehydrogenative coupling reaction of DMF with 2-substituted phenols to form organic carbamates through CH activation under oxidative conditions. The Cu2(BPDC)2(BPY) offered higher catalytic activity than common copper salts such as Cu(OAc)2, CuCl, CuCl2, CuI, and Cu(NO3)2 as well as other Cu-MOFs such as Cu3(BTC)2, Cu(BDC), and Cu(BPDC). The Cu2(BPDC)2(BPY) catalyst could be facilely separated from the reaction mixture, could be recovered and reused several times without significant degradation in catalytic activity.
- Phan, Nam T.S.,Nguyen, Tung T.,Vu, Phuong H. L.
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p. 3068 - 3077
(2013/10/21)
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