- Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
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The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
- Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
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- Electrochemical Radical Borylation of Aryl Iodides
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Herein, we report the first electrochemical strategy for the borylation of aryl iodides via a radical pathway using current as a driving force. A mild reaction condition allows an assorted range of readily available aryl iodides to be proficiently converted into synthetically valuable arylboronic esters under transition metal catalyst-free conditions. Moreover, this method also shows good functional group tolerance. Initial control mechanistic experiments reveal the formation of aryl radical as a key intermediate and the current plays an important role in the generation of radical intermediate.
- Hong, Junting,Liu, Qianyi,Li, Feng,Bai, Guangcan,Liu, Guoquan,Li, Man,Nayal, Onkar S.,Fu, Xuefeng,Mo, Fanyang
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supporting information
p. 347 - 351
(2019/03/07)
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- Transition-Metal-Free Poly(thiazolium) Iodide/1,8-Diazabicyclo[5.4.0]undec-7-ene/Phenazine-Catalyzed Esterification of Aldehydes with Alcohols
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Poly(3,4-dimethyl-5-vinylthiazolium) iodide was used as a polymer precatalyst in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and phenazine for the oxidative esterification of aldehydes with alcohols. Selective functionalization of OH groups was achieved in the presence of NH2 groups. The poly(thiazolium) iodide/DBU/phenazine system exhibited excellent catalytic activity and could be reused five times without loss of activity.
- Chun, Supill,Chung, Young Keun
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supporting information
p. 3787 - 3790
(2017/07/26)
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- Highly Active Manganese-Mediated Acylation of Alcohols with Acid Chlorides or Anhydrides
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To explore further the practical uses of highly active manganese (Mn?), a variety of alcohols were treated with Mn?, and the resulting complexes were coupled with acid chlorides and/or acetic anhydride in the absence of any extra catalyst. The subsequent reactions took place smoothly under mild conditions, providing the corresponding O-acylation products in good to excellent isolated yields.
- Joo, Seong-Ryu,Youn, Young-Jin,Hwang, Young-Ran,Kim, Seung-Hoi
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p. 2665 - 2669
(2017/10/07)
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- Copper-promoted reductive coupling of aryl iodides with 1,1,1-trifluoro-2-iodoethane
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An efficient Cu-promoted reductive coupling of aryl iodides with 1,1,1-trifluoro-2-iodoethane has been developed. This reaction could occur in good yields under milder conditions as compared with previous studies. The reaction tolerated nitro, formyl, ester, ether, carbonyl, sulfonyl, and even azo groups.
- Xu, Song,Chen, Huan-Huan,Dai, Jian-Jun,Xu, Hua-Jian
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supporting information
p. 2306 - 2309
(2014/05/20)
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- The role of cyclobutenes in gold(I)-catalysed skeletal rearrangement of 1,6-enynes
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1,6-Enynes with electron-donating substituents at the alkyne undergo gold(i)-catalysed single cleavage skeletal rearrangement, whereas substrates with electron-withdrawing substituents evolve selectively to double cleavage rearrangement. Theoretical calcu
- Escribano-Cuesta, Ana,Perez-Galan, Patricia,Herrero-Gomez, Elena,Sekine, Masaki,Braga, Ataualpa A. C.,Maseras, Feliu,Echavarren, Antonio M.
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supporting information; experimental part
p. 6105 - 6111
(2012/09/05)
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- Palladium/NHC-catalyzed oxidative esterification of aldehydes with phenols
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A palladium-catalyzed oxidative esterification of aldehydes with phenols is described, using air as the clean oxidant. This reaction tolerates many functional groups, providing esters with yields ranging from moderate to excellent.
- Zhang, Manli,Zhang, Shouhui,Zhang, Guoying,Chen, Fan,Cheng, Jiang
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experimental part
p. 2480 - 2483
(2011/05/16)
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- Efficient and controllably selective preparation of esters using uronium-based coupling agents
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Carboxylic acid esters can be prepared in excellent yields at room temperature from an acid and either a phenol or an aliphatic alcohol using the peptide coupling reagents, TBTU, TATU, or COMU, in the presence of organic bases. Reactions using TBTU and TATU are faster but do not occur with tertiary alcohols. Selectivity between reaction with primary or secondary alcohols in diols and polyols can be achieved with choice of base and coupling agent.
- Twibanire, Jean-D'Amour K.,Grindley, T. Bruce
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supporting information; experimental part
p. 2988 - 2991
(2011/08/04)
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- Assembled catalyst of palladium and non-cross-linked amphiphilic polymer ligand for the efficient heterogeneous Heck reaction
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The efficient heterogeneous Heck reaction was achieved by a new networked and supramolecular catalyst PdAS-V (1b). Employing of PdAS-V in 5.0×10-5molequiv. efficiently progressed the heterogeneous Heck reaction of a series of aryl iodides with acrylates, styrenes and acrylic acid. PdAS-V was successfully recycled five times without any decrease in its activity, and showed good stability in toluene and water, and hence the Heck reaction was efficiently performed in both reaction media. The use of 8.0×10-7molequiv. of PdAS-V resulted in the coupling product in 92% yield with the turnover number (TON) and the turnover frequency (TOF) of PdAS-V reached up to 1,150,000 and 12,000, respectively. The efficient synthesis of resveratrol was achieved via the PdAS-V-promoted Heck reaction.
- Yamada, Yoichi M. A.,Takeda, Koji,Takahashi, Hideyo,Ikegami, Shiro
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p. 4097 - 4105
(2007/10/03)
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- Synthesis and mesomorphic properties of some fluoro-substituted benzoates
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Several series of fluoro-substituted benzoate liquid crystals have been synthesized. The results showed that the SmA phase is enhanced with the increasing of the degree of fluoro-substitution on the para- and meta-position of the terminal phenyl groups. And the molecules which have same molecular structural formula show nearly the same melting points. It is also discussed about the effect of the ester bond's direction on the mesomorphic properties.
- Yang,Tang,Gong,Wen
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p. 153 - 165
(2007/10/03)
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