- Synthesis of Pyrazolo[1,2-a]cinnolines via Rhodium(III)-Catalyzed [4+2] Annulation Reactions of Pyrazolidinones with Sulfoxonium Ylides
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A method to synthesize pyrazolo[1,2-a]cinnolines via rhodium(III)-catalyzed C?H activation of pyrazolidinones and subsequent [4+2] annulation of sulfoxonium ylides was developed. 5-Substituted or 5,10-disubstituted pyrazolo[1,2-a]cinnolines could be obtained by slightly adjusting the reaction conditions. Gram-scale synthesis and practical transformations proved the practicability of this method. The mechanism of this method was proposed in the article on the basis of preliminary mechanistic results and previous reports. This method features simplified operation, metal-oxidant free, and readily available reactants. (Figure presented.).
- Fang, Feifei,Han, Xu,Hu, Shulei,Liu, Hong,Saidahmatov, Abdusaid,Wang, Jiang,Wang, Yong,Xie, Xiong
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- Ruthenium(II)-Catalyzed Oxidative Double C-H Activation and Annulation Reaction: Synthesis of Indolo[2,1- a]isoquinolines
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The first metal-catalyzed double aryl C(sp2)-H bond activation of antipyrine and alkyne annulation reaction is reported. This Ru(II)-catalyzed reaction was accomplished in the presence of 20 mol % phosphine ligand tricyclohexylphosphine tetrafluoroborate to afford indolo[2,1-a]isoquinolines that are very important compounds because of their bioactivity and interesting optical properties.
- Borthakur, Somadrita,Sarma, Bipul,Gogoi, Sanjib
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p. 7878 - 7882
(2019/10/11)
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- Ru(II)-Catalyzed C-H Activation and Annulation Reaction via Carbon-Carbon Triple Bond Cleavage
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An unprecedented Ru(II)-catalyzed C-H activation and annulation reaction, which proceeds via C-C triple bond cleavage, is reported. This reaction of 2-phenyldihydrophthalazinediones with alkynes, which works most efficiently in the presence of bidented ligand 1,3-bis(diphenylphosphino)propane, affords good yields of substituted quinazolines.
- Prakash, Rashmi,Bora, Bidisha R.,Boruah, Romesh C.,Gogoi, Sanjib
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p. 2297 - 2300
(2018/04/30)
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- Ru(II)-Catalyzed and Ligand-Controlled C-H Activation and Annulation via 1,2-Phenyl Shift: Synthesis of Quaternary Carbon-Centered Pyrimidoindolones
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A novel Ru(II)-catalyzed C-H activation and annulation reaction of N-arylpyrazol-5-ones and diaryl/arylalkyl-substituted alkynes is developed. Unlike the reported metal-catalyzed C-H activation and annulation reactions, in the present bidentate amine-ligand controlled C-H activation and annulation reaction, the annulation occurs via a 1,2-aryl shift to afford quaternary carbon-centered pyrimidoindolones.
- Baruah, Swagata,Saikia, Pallabi,Duarah, Gauri,Gogoi, Sanjib
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p. 3753 - 3757
(2018/07/25)
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- Regioselective synthesis of indoles via rhodium-catalyzed C-H activation directed by an in-situ generated redox-neutral group
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A regioselective synthesis of indoles from arylhydrazine hydrochlorides with alkynes and diethyl ketone catalyzed by a rhodium complex is described. A possible mechanism involving an in-situ generated oxidizing directing group -N-Ni'CR1R2 assisted ortho-C-H activation and reductive elimination are proposed. The catalytic reaction is highly compatible with a wide range of functional arylhydrazines and alkynes. The reaction proceeds under mild reaction conditions and is atom-step economical.
- Muralirajan, Krishnamoorthy,Cheng, Chien-Hong
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p. 1571 - 1576
(2014/06/09)
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- Rhodium(III)-catalyzed c-h activation and indole synthesis with hydrazone as an auto-formed and auto-cleavable directing group
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An efficient, practical, and external-oxidant-free indole synthesis from readily available aryl hydrazines was developed, by using hydrazone as a directing group for RhIII-catalyzed C-H activation and alkyne annulation. The hydrazone group was formed by in situ condensation of hydrazines and Ci£O source, whereas its N-N bond was served as an internal oxidant, for which we termed it as an auto-formed and auto-cleavable directing group (DGauto). This method needs no step for pre-installation and post-cleavage of the directing group, making it a quite easily scalable approach to access unprotected indoles with high step economy. The DGauto strategy was also applicable for isoquinoline synthesis. In addition, synthetic utilities of this chemistry for rapid assembly of π-extended nitrogen-doped polyheterocycles and bioactive molecules were demonstrated. Copyright
- Zheng, Liyao,Hua, Ruimao
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supporting information
p. 2352 - 2356
(2014/03/21)
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- Relative quantitation of glycans using stable isotopic labels 1-(d0/d5) phenyl-3-methyl-5-pyrazolone by mass spectrometry
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A deuterium reagent, 1-(d5) phenyl-3-methyl-5-pyrazolone (d5-PMP), has been synthesized and used for relative quantitative analysis of oligosaccharides by mass spectrometry (MS) using d0/d5-PMP stable isotopic labeling. Previously reported permethylation-based isotopic labels generate variable mass differences, and reductive amination-based isotopic labels cause a loss of some acid-labile groups in carbohydrates. In contrast, d0/d5-PMP stable isotopic labeling is performed at the reducing end of glycans under basic conditions without desialylation, and the mass difference (Δm = 10 Da) between the heavy form (d5-PMP derivative) and light form (d0-PMP derivative) of each glycan is invariable. When the two derivative forms of a glycan are mixed in equimolar amounts, a pair of peaks with a 10-Da mass differences is observed in the MS profile. The difference at relative intensity between the d0- and d5-PMP derivatives reflects the difference in quantity of glycans in two samples, making it possible to carry out both qualitative and relative quantitative analyses of glycans in glycomic studies. Application of this method on DP 2 to DP6 maltodextrin oligosaccharides and N-linked glycans released from ribonuclease B and bovine fetuin demonstrates a 10-fold relative quantitative dynamic range, a satisfying reproducibility (coefficient of variation [CV] ≤ 8.34%), and good accuracy (relative error [RE] ≤ 5.1%) of the method. The suggested technique has been successfully applied for comparative quantitative analysis of free oligosaccharides in human and bovine milk.
- Zhang, Ping,Zhang, Ying,Xue, Xiangdong,Wang, Chenjian,Wang, Zhongfu,Huang, Linjuan
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experimental part
p. 1 - 9
(2012/07/14)
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