- Cobalt(ii)-catalyzed benzylic oxidations with potassium persulfate in TFA/TFAA
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A cobalt-catalyzed C(sp3)-H oxygenation reaction to furnish aldehyde was herein reported. This transformation demonstrated high chemo-selectivity, and tolerated various methylarenes bearing electron-withdrawing substituents. This reaction provided rapid access to diverse aldehydes form methylarenes. Notably, TFA/TFAA was used for the first time as a mixed solvent in cobalt-catalyzed oxygenation of benzylic methylenes.
- Li, Tianlei,Li, Jishun,Zhu, Zihao,Pan, Weidong,Wu, Song
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p. 20879 - 20883
(2019/07/12)
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- Zincation and Magnesiation of Functionalized Silylated Cyanohydrins Using TMP-Bases
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Polyfunctional silylated cyanohydrins are readily magnesiated or zincated with TMPMgCl·LiCl or TMP 2 Zn·2MgCl 2 ·2LiCl leading to the corresponding metallated derivatives. These Mg- or Zn-derivatives react with various electrophiles such as benzylic bromides, allylic bromides, acid chlorides, aldehydes, NCCO 2 Et, or MeSO 2 SMe. Subsequently, TBAF-deprotection provides the corresponding keto or 1,2-diketo derivatives.
- Castelló-Micó, Alicia,Knochel, Paul
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p. 155 - 169
(2017/10/07)
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- Development of a Rhodium(II)-Catalyzed Chemoselective C(sp3)-H Oxygenation
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We report the first example of RhII-catalyzed chemoselective double C(sp3)-H oxygenation, which can directly transform various toluene derivatives into highly valuable aromatic aldehydes with great chemoselectivity and practicality. The critical combination of catalyst Rh(OAc)2, oxidant Selectfluor, and solvents of TFA/TFAA promises the successful delivery of the oxidation with satisfactory yields. A possible mechanism involving a unique carbene-Rh complex is proposed, and has been supported by both experiments and theoretical calculations.
- Lin, Yun,Zhu, Lei,Lan, Yu,Rao, Yu
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supporting information
p. 14937 - 14942
(2015/10/19)
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- Silylation improves the photodynamic activity of tetraphenylporphyrin derivatives in vitro and in vivo
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The effects of silyl and hydrophilic groups on the photodynamic properties of tetraphenylporphyrin (TPP) derivatives have been studied in vitro and in vivo. Silylation led to an improvement in the quantum yield of singlet oxygen sensitization for both sulfo and carboxy derivatives, although the silylation did not affect other photophysical properties. Silylation also improved the cellular uptake efficiency for both sulfo and carboxy derivatives, enhancing the in vitro photodynamic activity of the photosensitizer in U251 human glioma cells. The carboxy derivative (SiTPPC4) was found to show higher cellular uptake efficiency and in vitro photodynamic activity than the corresponding sulfo derivative (SiTPPS4), which indicates that the carboxy group is a more promising hydrophilic group than the sulfo group in the silylated porphyrin. SiTPPC4 was found to show high selective accumulation efficiency in tumors, although almost no tumor selectivity was observed for the nonsilylated porphyrin. The concentration of SiTPPC4 in tumors was 13 times higher than that in muscle 12 h after drug administration. We also studied tumor response after treatment and found that silylation enhanced in vivo photodynamic activity significantly. SiTPPC 4 shows higher photodynamic activity than NPe6 with white light irradiation. Improved photosensitizers: Silylation improves the quantum yield of singlet oxygen sensitization, cellular uptake efficiency, and selective accumulation efficiency in tumors. As a result of these improvements, silylation significantly enhances photodynamic activity (see figure). The results of this work suggest that silylation is a promising strategy for improving photosensitizers for photodynamic therapy.
- Horiuchi, Hiroaki,Hosaka, Masahiro,Mashio, Hiroyuki,Terata, Motoki,Ishida, Shintaro,Kyushin, Soichiro,Okutsu, Tetsuo,Takeuchi, Toshiyuki,Hiratsuka, Hiroshi
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p. 6054 - 6060
(2014/05/20)
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- Cobalt carbonyl as an effective CO source in one-pot synthesis of esters from aryl halides
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For the first time, we have successfully applied Co2(CO) 8 as an effective carbonyl source for the Pd catalysed alkoxycarbonylation of aryl halides affording the corresponding aryl esters under mild microwave conditions. A wide variety of esters and carbonyl derivatives were prepared using this protocol.
- Baburajan,Senthilkumaran,Elango, Kuppanagounder P.
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p. 3050 - 3056
(2013/10/01)
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- A simple and convenient manganese dioxide oxidation of benzyl halides to aromatic aldehydes under neutral condition
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A simple, convenient and inexpensive benzylic oxidation reaction of arylmethylhalides under neutral conditions by manganese dioxide to the corresponding aldehydes has been described. Copyright
- Goswami, Shyamaprosad,Jana, Subrata,Dey, Swapan,Adak, Avijit Kumar
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p. 194 - 195
(2007/10/03)
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- Aromatic aldehydes from benzylbromides via Cobalt(I) mediated benzyl radicals in the presence of aerial oxygen: A mild oxidation reaction in neutral condition
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Co(PPh3)3Cl has been shown to be a novel mediator for the conversion of benzylic bromides to aromatic aldehydes under mild conditions in the presence of acnal oxygen probably via benzylic radicals. In the absence of oxygen, the carbon-carbon coupling reactions have been utilised to attend a series of functionalised benzylic dimers.
- Goswami, Shyamaprosad,Mahapatra, Ajit Kumar
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p. 1981 - 1984
(2007/10/03)
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