- Pd-Catalyzed Decarboxylative Ortho-Halogenation of Aryl Carboxylic Acids with Sodium Halide NaX Using Carboxyl as a Traceless Directing Group
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A highly regioselective Pd-catalyzed carboxyl directed decarboxylative ortho-C-H halogenation of cheap o-nitrobenzoic acids with NaX (X = I, Br) under aerobic conditions has been established. The utility of the method has been demonstrated by the gram-scale reaction and derivatization of the product. Experimental results have confirmed Pd and Bi played critical roles in the transformation and indicated the transformation might proceed via 2-halo-6-nitrobenzoic acid derivative intermediate.
- Fu, Zhengjiang,Jiang, Yongqing,Wang, Shuiliang,Song, Yuanyuan,Guo, Shengmei,Cai, Hu
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supporting information
p. 3003 - 3007
(2019/05/10)
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- 1,3-dibromo-4-fluorobenzene preparation method
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The invention discloses an industrial preparation method of 1,3-dibromo-4-fluorobenzene. The industrial preparation method of 1,3-dibromo-4-fluorobenzene comprises the steps that o-fluoronitrobenzeneserves as an initial raw material, and 1,3-dibromo-4-fluorobenzene is synthesized through bromine applying, reduction and diazotization-Sandmeyer three step reactions. The obtained 1,3-dibromo-4-fluorobenzene is yellow oily liquid, the purity is 97.5%, the raw material conversion rates of all steps each reach 100%, and the total recovery of the whole process reaches 52.7%.
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Paragraph 0010; 0013
(2019/02/27)
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- A 3-amino-4-fluorophenylboronic acid synthesis method
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The invention discloses a synthetic method for 3-amino-4-fluorophenylboronic acid. The method includes the steps of conducting bromination on o-fluoronitrobenzene, conducting reduction to generate 5-bromo-2-fluoroanil, making 5-bromo-2-fluoroanil and tetrahydroxydiboron react in a coupled mode to generate the product, namely, 3-amino-4-fluorophenylboronic acid. According to the method, raw materials can be easily obtained, and operation is easy and convenient. The method is an appropriate route for preparing 3-amino-4-fluorophenylboronic acid.
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Paragraph 0026
(2016/11/24)
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- N-halosuccinimide/BF3-H2O, efficient electrophilic halogenating systems for aromatics
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N-Halosuccinimides (NXS, 1) are efficiently activated in trifluoromethanesulfonic acid and BF3-H2O, allowing the halogenations of deactivated aromatics. Because BF3-H2O is more economic, easy to prepare, nonoxidizing, and offers sufficiently high acidity (-H0 ≈ 12, only slightly lower than that of trifluoromethanesulfonic acid), an efficient new electrophilic reagent combination of NXS/BF3-H2O has been developed. DFT calculations at the B3LYP/6-311++G**//B3LYP/6-31G* level suggest that protonated N-halosuccinimides undergo further protosolvation at higher acidities to reactive superelectrophilic species capable either in the transfer of X+ from the protonated forms of NXS to the aromatic substrate or in forming a highly reactive and solvated X+ which would readily react with the aromatic substrates. Structural aspects of the BF 3-H2O complex have also been investigated.
- Prakash, G. K. Surya,Mathew, Thomas,Hoole, Dushyanthi,Esteves, Pierre M.,Wang, Qi,Rasul, Golam,Olah, George A.
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p. 15770 - 15776
(2007/10/03)
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- Syntheses of Sulfonated Derivatives of 2-Fluoroaniline
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Synthesis of 4-amino-3-fluorobenzenesulfonic acid (3) was achieved in two ways: reaction of 2-fluoroaniline (1) with amidosulfonic acid and by first conventionally converting 4-nitro-3-fluoroaniline (8) to 4-nitro-3-fluorobenzenesulfonyl chloride (9) followed subsequently by hydrolysis to 3-fluoro-4-nitrobenzenesulfonic acid (10) and reduction.Hydrogenolysis of 3 gave sulfanilic acid (7).Both, sulfonation of fluorobenzene (6) to 4-fluorobenzenesulfonic acid (11) followed by nitration and sulfonation of 1-fluoro-2-nitrobenzene (12) led to 4-fluoro-3-nitrobenzenesulfonic acid (13).Reduction of 13 gave the isomeric 3-amino-4-fluorobenzenesulfonic acid (4), which was also obtained both by sulfonation of 1 and by sulfonation of o-fluoroacetanilide (14) followed by hydrolysis.Selective hydrogenolyses of 2-amino-5-bromo-3-fluorobenzenesulfonic acid (15), prepared by reaction of 4-bromo-2-fluoroaniline (16) with amidosulfonic acid, and of 4-amino-2-bromo-5-fluorobenzenesulfonic acid (20), obtained by sulfonation of 5-bromo-2-fluoroaniline (19) yielded the isomers 2-amino-3-fluorobenzenesulfonic acid (5) and 3, respectively.The fourth isomer, 3-amino-2-fluorobenzenesulfonic acid (2), was synthesized by sulfur dioxide treatment of the diazonium chloride derived from 2-fluoro-3-nitroaniline (21) to 2-fluoro-3-nitrobenzenesulfonyl chloride (22), followed by hydrolysis to 2-fluoro-3-nitrobenzenesulfonic acid (23) and final Bechamp-reduction.
- Courtin, Alfred
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