- NFSI/KF mediated mild and chemoselective interconversion of aryl TBDMS ethers to their benzene sulfonate
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A one pot protocol for the transformation of aryl TBDMS ethers to corresponding benzene sulfonate esters using NFSI (N-flurobenzenesulfonimide)/KF is described. In situ generation of benzenesulfonyl fluoride directs chemoselective cleavage of aryl silyl ethers over alkyl silyl ethers. Electron withdrawing substituent's on aryl ring provided better yield than donating groups. Protecting groups and sensitive functionalities are well tolerated in this methodology. Thus, commercially available inexpensive reagents, mild reaction conditions and step economy are the advantages of this method.
- Dond, Bharat D.,Thore, Shivaji N.
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supporting information
(2020/02/06)
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- A reagent chloride nitrogen chlorine
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The invention relates to a nitrogen-chorine type chlorination agent, and belongs to the field of chlorination agent synthesis. The nitrogen-chorine type chlorination agent is obtained by taking benzene sulfonamide as a substrate, introducing fluorine gas and chlorine gas to react. In the synthesis process, a commercial product is taken as a raw material, the operation is simple, the separation is easy and the yield is high. When chlorination reaction is performed, the conditions are mild, the yield is high and the reaction substrate applied range is wide. Especially, the nitrogen-chorine type chlorination agent has good chlorination activity to dicarbonyl compounds, indole compounds and nitrogen-containing heterocyclic ring compounds.
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Paragraph 0028-0031
(2017/02/28)
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- Nucleophilic reactivity towards electrophilic fluorinating agents: Reaction with N-fluorobenzenesulfonimide ((PhSO2)2NF)
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Second-order rate constants for the reaction of N-fluorobenzenesulfonimide (FBS) with nucleophilic reagents, kNu (M-1 s-1), have been measured in aqueous solution at 25°C. Analysis of the reaction products shows that soft polarizable nucleophiles (I-, SCN-, Br-) react at fluorine, whereas hard nucleophiles (oxygen and nitrogen nucleophiles) react at sulfur. The ambident behaviour of this electrophile seems to be related to the relative contribution of electrostatic and orbital interactions in reaching the transition state. The preferential reaction of soft nucleophiles at fluorine and the correlation of kNu values with the one-electron oxidation potentials of the nucleophiles in water suggest that nucleophilic reactivity at fluorine is largely determined by the ease of one-electron transfer from the nucleophile to the electrophile. Nucleophilic addition to fluorine is far more sensitive to the nature of the attacking nucleophile than the corresponding reactions at both saturated (n scale) and unsaturated carbon (N+ scale). Comparison of the rate constants for the reaction of nucleophiles at the sulfonyl group with those for reaction of the same nucleophiles with 2,4-dinitrophenyl acetate reveals a similar reactivity pattern for sulfonyl sulfur and carbonyl carbon as electrophilic centres.
- Antelo, Juan M.,Crugeiras, Juan,Leis, J. Ramon,Rios, Ana
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p. 2071 - 2076
(2007/10/03)
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