Hyper-Cross-Linked Polymer with Enhanced Porosity by In Situ Removal of Trimethylsilyl Group via Electrophilic Aromatic Substitution

A safe, convenient, and regioselective synthesis of 3-halo coumarins using a metal halide (CuX2 alone or with ZnX2) promoted halogenation with N-halosuccinimide (NXS) as halide source is reported. The synthesis involved the steady in situ generation of highly reactive positive halogen (X+) by the coordination of copper or zinc with the N-halosuccinimide and subsequent electrophilic aromatic substitution of the electron-deficient coumarins. This procedure works well also for the halogenation of less electron-rich naphthoquinones, flavones, and methoxypsoralen in moderate to quantitative yields. This protocol features simple experimental conditions using readily available inexpensive reagents and provides a convenient approach to the chlorination or bromination of some useful heteroaromatic compounds.

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Preparation of Benzene Derivatives: The Yu/Baran Synthesis of (+)-Hongoquercin A

Organic Synthesis ◽

10.1093/oso/9780190646165.003.0061 ◽

2017 ◽

Author(s):

Douglass F. Taber

Keyword(s):

Electrophilic Aromatic Substitution ◽

University Of Michigan ◽

Aromatic Substitution ◽

Blocking Group ◽

University Of Texas ◽

University Of Houston ◽

National University ◽

Reformatsky Reagent ◽

The University

Lutz Ackermann of the Georg-August-Universität Göttingen oxidized (Org. Lett. 2013, 15, 3484) the anisole derivative 1 to the phenol 2. Melanie S. Sanford of the University of Michigan devised (Org. Lett. 2013, 15, 5428) complementary conditions for either para acetoxylation of 3, illustrated, to give 4, or meta acetoxylation. Lukas J. Goossen of the Technische Universität Kaiserlautern developed (Synthesis 2013, 45, 2387) conditions for the cascade alkoxylation/decarboxylation of 5 to give 6. Cheol-Hong Cheon of Korea University showed (J. Org. Chem. 2013, 78, 12154) that the boronic acid of 7 could act as a blocking group during electrophilic aromatic substitution or, as illustrated, as an ortho directing group. It could then be removed by protodeboronation, leading to 8. Jun Wu of Zhejiang University coupled (Synlett 2013, 24, 1448) the phenol 9 with the bromo amide 10 to give an ether that, on exposure to KOH at elevated temperature, rearranged to the intermediate amide, that was then hydrolyzed to 11. Dong-Shoo Shin of Changwon National University reported (Tetrahedron Lett. 2013, 54, 5151) a similar protocol (not illustrated) to prepare unsubstituted anilines. Guangbin Dong of the University of Texas, Austin used (J. Am. Chem. Soc. 2013, 135, 18350) a variation on the Catellani reaction to add 13 to the ortho bromide 12 to give the meta amine 14. Kei Manabe of the University of Shizuoka found (Angew. Chem. Int. Ed. 2013, 52, 8611) that the crystalline N-formyl saccharin 16 was a suitable CO donor for the carbonylation of the bromide 15 to the aldehyde 17. John F. Hartwig of the University of California, Berkeley described (J. Org. Chem. 2013, 78, 8250) the coupling of the zinc enolate of an ester (Reformatsky reagent), either preformed or generated in situ, with an aryl bromide 18 to give 19. Olafs Daugulis of the University of Houston developed (Org. Lett. 2013, 15, 5842) conditions for the directed ortho phenoxylation of 20 with 21 to give 22. Yao Fu of the University of Science and Technology of China effected (J. Am. Chem. Soc. 2013, 135, 10630) directed ortho cyanation of 23 with 24 to give 25.

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Synthesis of Aromatic and Aliphatic Di-, Tri-, and Tetrasulfonic Acids

Synlett ◽

10.1055/s-0039-1691745 ◽

2020 ◽

Vol 31 (10) ◽

pp. 945-952

Author(s):

Jens Christoffers ◽

Mathias S. Wickleder

Keyword(s):

Nucleophilic Aromatic Substitution ◽

Electrophilic Aromatic Substitution ◽

Aromatic Substitution ◽

Nucleophilic Substitutions ◽

Sulfonic Acids ◽

Subsequent Oxidation ◽

Aromatic Substrates ◽

Diazonium Ions ◽

Metal Organic

Oligosulfonic acids are promising linker compounds for coordination polymers and metal-organic frameworks, however, compared to their carboxylic acid congeners, often not readily accessible by established synthetic routes. This Account highlights the synthesis of recently developed aromatic and aliphatic di-, tri- and tetrasulfonic acids. While multiple electrophilic sulfonations of aromatic substrates are rather limited, the nucleophilic aromatic substitution including an intramolecular variant, the Newman–Kwart rearrangement, allows the flexible introduction of up to four sulfur-containing moieties at an aromatic ring. Sulfonic acids are then accessed by oxidation of thiols, thioethers, or thioesters either directly with hydrogen peroxide or in two steps with chlorine (generated in situ from N-chlorosuccinimide/hydrochloric acid) to furnish sulfochlorides which are subsequently hydrolyzed. In the aliphatic series, secondary alcohols as starting materials are converted into thioethers, thioesters, or thiocarbonates by nucleophilic substitutions, which are also subsequently oxidized to furnish sulfonic acids.1 Introduction2 Electrophilic Aromatic Substitution3 Nucleophilic Aromatic Substitution3.1 Intermolecular SNAr3.2 Intermolecular with Subsequent Oxidation3.3 Intramolecular with Subsequent Oxidation4 Nucleophilic Aliphatic Substitution with Subsequent Oxidation5 Oxidation5.1 Oxidation of Thiocarbonates5.2 Oxidation of Thioethers5.3 Oxidation of Thioesters6 Thermolysis of Neopentylsulfonates7 Functionalization via Diazonium Ions8 Conclusion

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Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19802219 ◽

1980 ◽

Vol 45 (8) ◽

pp. 2219-2223 ◽

Cited By ~ 6

Author(s):

Marie Jakoubková ◽

Martin Čapka

Keyword(s):

Catalytic Activity ◽

Nmr Spectroscopy ◽

Ir Spectroscopy ◽

Electron Density ◽

Phosphorus Atom ◽

Proton Acceptor ◽

Trimethylsilyl Group ◽

Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

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