ChemInform Abstract: AROMATIC SUBSTITUTION. 48. BORON TRIFLUORIDE CATALYZED NITRATION OF AROMATICS S WITH SILVER NITRATE IN ACETONITRILE SOLUTION

The synthesis of novel fluorescent N(9)-alkylated 2-amino-6-triazolylpurine and 7-deazapurine derivatives is described. A new C(2)-regioselectivity in the nucleophilic aromatic substitution reactions of 9-alkylated-2,6-diazidopurines and 7-deazapurines with secondary amines has been disclosed. The obtained intermediates, 9-alkylated-2-amino-6-azido-(7-deaza)purines, were transformed into the title compounds by CuAAC reaction. The designed compounds belong to the push–pull systems and possess promising fluorescence properties with quantum yields in the range from 28% to 60% in acetonitrile solution. Due to electron-withdrawing properties of purine and 7-deazapurine heterocycles, which were additionally extended by triazole moieties, the compounds with electron-donating groups showed intramolecular charge transfer character (ICT/TICT) of the excited states which was proved by solvatochromic dynamics and supported by DFT calculations. In the 7-deazapurine series this led to increased fluorescence quantum yield (74%) in THF solution. The compounds exhibit low cytotoxicity and as such are useful for the cell labelling studies in the future.

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Nucleophilic Aromatic Substitution with 2,3-Dihydro-1,3-diisopropyl- 4,5-dimethylimidazol-2-ylidene

Zeitschrift für Naturforschung B ◽

10.1515/znb-2009-1010 ◽

2009 ◽

Vol 64 (10) ◽

pp. 1176-1182 ◽

Cited By ~ 21

Author(s):

Eyad Mallah ◽

Norbert Kuhn ◽

Cäcilia Maichle-Mößmer ◽

Manfred Steimann ◽

Markus Ströbele ◽

...

Keyword(s):

Crystal Structure ◽

Boron Trifluoride ◽

Mass Spectra ◽

Nucleophilic Aromatic Substitution ◽

Aromatic Substitution ◽

Preparative Scale ◽

Fab Mass Spectra

2,3-Dihydro-1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (1) reacts with an excess of hexafluorobenzene in the presence of boron trifluoride diethyletherate to give 1,3-diisopropyl-4,5- dimethyl-2-(perfluorophenyl)imidazolium tetrafluoroborate (2). Solutions of 2 exhibit an equilibrium consisting also of hexafluorobenzene and 2,2ʹ-(perfluoro-1,4-phenylene)bis(1,3-diisopropyl- 4,5-dimethylimidazolium)bis(tetrafluoroborate) (3) which is obtained from 1 and hexafluorobenzene in the ratio 2 : 1 on a preparative scale. Similar to 2, 2-(4-cyano-2,3,5,6-tetrafluorophenyl)-1,3- diisopropyl-4,5-dimethylimidazolium tetrafluoroborate (4), 2-(2,4-dicyano-2,5,6-trifluorophenyl)- 1,3-diisopropyl-4,5-dimethylimidazolium tetrafluoroborate (5), and 2-(4,6-difluoro-1,3,5-triazin-2- yl)-1,3-diisopropyl-4,5-dimethylimidazolium tetrafluoroborate (6) are obtained from 1 and perfluorobenzonitrile, 1,3-dicyano-2,4,5,6-tetrafluorobenzene, and 2,4,6-trifluoro-1,3,5-triazin, respectively. The FAB mass spectra of compounds 2 - 6 and the results of the crystal structure analyses of compounds 2 - 4 are discussed.

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Aromatic substitution. XXXV. Boron trifluoride catalyzed nitration of benzene, alkylbenzenes, and halobenzenes with methyl nitrate in nitromethane solution

Journal of the American Chemical Society ◽

10.1021/ja00816a038 ◽

1974 ◽

Vol 96 (9) ◽

pp. 2892-2898 ◽

Cited By ~ 22

Author(s):

George A. Olah ◽

Henry C. Lin

Keyword(s):

Boron Trifluoride ◽

Aromatic Substitution ◽

Methyl Nitrate

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ChemInform Abstract: AROMATIC SUBSTITUTION PART 35, BORON TRIFLUORIDE CATALYZED NITRATION OF BENZENE, ALKYLBENZENES, AND HALOBENZENES WITH METHYL NITRATE IN NITROMETHANE SOLUTION

Chemischer Informationsdienst ◽

10.1002/chin.197427170 ◽

1974 ◽

Vol 5 (27) ◽

pp. no-no

Author(s):

GEORGE A. OLAH ◽

HENRY C. LIN

Keyword(s):

Boron Trifluoride ◽

Aromatic Substitution ◽

Methyl Nitrate

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The `super acid' BF3H2O stabilized by 1,4-dioxane: new preparative aspects and the crystal structure of BF3H2O·C4H8O2

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989019014312 ◽

2019 ◽

Vol 75 (11) ◽

pp. 1787-1791

Author(s):

Peter Barthen ◽

Walter Frank

Keyword(s):

Crystal Structure ◽

Hydrogen Bond ◽

Hydrogen Bonds ◽

Structural Feature ◽

Boron Trifluoride ◽

Acetonitrile Solution ◽

Ionic Character ◽

Zigzag Chain ◽

Hydrogen Bond Acceptor ◽

Super Acid

Highly Brønsted-acidic boron trifluoride monohydrate, a widely used `super acid-catalyst', is a colourless fuming liquid that releases BF3 at room temperature. Compared to the liquid components, i.e. boron trifluoride monohydrate and 1,4-dioxane, their 1:1 adduct, BF3H2O·C4H8O2, is a solid with pronounced thermal stability (m.p. 401–403 K). The crystal structure of the long-time-stable easy-to-handle and weighable compound is reported along with new preparative aspects and the results of 1H, 11B, 13C and 19F spectroscopic investigations, particularly documenting its high Brønsted acidity in acetonitrile solution. The remarkable stability of solid BF3H2O·C4H8O2 is attributed to the chain structure established by O—H...O hydrogen bonds of exceptional strength {O2...H1—O1 [O...O = 2.534 (3) Å] and O1—H1...O3i [2.539 (3) Å] in the concatenating unit >O2...H1—O1—H2...O3i<}, taking into account the molecular (non-ionic) character of the structural moieties. Indirectly, this structural feature documents the outstanding acidification of the H2O molecule bound to BF3 and reflects the super acid nature of BF3H2O. In detail, the C 2 2(7) zigzag chain system of hydrogen bonding in the title structure is characterized by the double hydrogen-bond donor and double (κO,κO′) hydrogen-bond acceptor functionality of the aqua ligand and dioxane molecule, respectively, the almost equal strength of both hydrogen bonds, the approximatety linear arrangement of the dioxane O atoms and the two neighbouring water O atoms. Furthermore, the approximately planar arrangement of B, F and O atoms in sheets perpendicular to the c axis of the orthorhombic unit cell is a characteristic structural feature.

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Photochemical nucleophile–olefin combination, aromatic substitution (photo-NOCAS) reaction. Part 7: methanol, conjugated dienes, and 1,4-dicyanobenzene

Canadian Journal of Chemistry ◽

10.1139/v94-292 ◽

1994 ◽

Vol 72 (11) ◽

pp. 2291-2304 ◽

Cited By ~ 11

Author(s):

Kimberly A. McManus ◽

Donald R. Arnold

Keyword(s):

Potassium Cyanide ◽

Addition Product ◽

Conjugated Dienes ◽

Acetonitrile Solution ◽

Mercury Vapour ◽

Aromatic Substitution ◽

Cyanide Ion ◽

Marked Contrast ◽

Methanol Solutions ◽

Mercury Vapour Lamp

The scope of the photochemical nucleophile–olefin combination, aromatic substitution (photo-NOCAS) reaction has been extended to include conjugated dienes: 1,3-butadiene (9), 2-methyl-1,3-butadiene (10), 2,3-dimethyl-1,3-butadiene (11), and 2,5-dimethyl-2,4-hexadiene (12). Acetonitrile–methanol solutions of the dienes 9,10, and 11, and 1,4-dicyanobenzene (1), with and without codonor (biphenyl (5)), were irradiated with a medium-pressure mercury vapour lamp through Pyrex. Both 1,2- and 1,4-addition products were formed in approximately equal amounts (combined yields of photo-NOCAS products, 50–65%). In marked contrast, when an acetonitrile–methanol solution of 2,5-dimethyl-2,4-hexadiene (12), 1, and 5 was irradiated, only the 1,4-addition product, trans-2-(4-cyanophenyl)-5-methoxy-2,5-dimethyl-3-hexene (22,82%), was obtained. This photolysate also contained a small amount of another 1,4-addition product, that which had incorporated cyanide ion instead of methanol, trans-2-(4-cyanophenyl)-2,2,5-trimethyl-3-hexenenitrile (23, 2%). Irradiation of an acetonitrile solution (no methanol) of 12,1, and 5 gave 23 in good yield (68%). An excellent yield (80%) of 23 was obtained upon irradiation of an acetonitrile solution of 1,12, 5, potassium cyanide, and 18-crown-6. Addition of 2,4,6-trimethylpyridine (collidine, 25), a mild, non-nucleophilic base, to the reaction mixture diverts the reaction involving 12 from photo-NOCAS products to 1:1 substitution products; 3-(4-cyanophe-nyl)-2,5-dimethyl-1,4-hexadiene (26), trans-5-(4-cyanophenyl)-2,5-dimethyl-1,3-hexadiene (27), (Z)-1-(4-cyanophenyl)-2,5-dimethyl-2,4-hexadiene (28), and (E)-1-(4-cyanophenyl-2,5-dimethyl-2,4-hexadiene (29) were formed. The mechanisms of these reactions are discussed and an explanation for the observed regio- and stereoselectivity is given.

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