- CARBOXYLATION CATALYSTS
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The use of a complex of the form Z—M—OR in the carboxylation of a substrate is described. The group Z is a two-electron donor ligand, M is a metal and OR is selected from the group consisting of OH, alkoxy and aryloxy. The substrate may be carboxylated at a C—H or N—H bond. The metal M may be copper, silver or gold. The two-electron donor ligand may be a phosphine, a carbene or a phosphite ligand. Also described are methods of manufacture of the complexes and methods for preparing isotopically labelled caboxylic acids and carboxylic acid derivatives.
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Paragraph 0093; 0095
(2013/04/13)
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- Carboxylation of C-H bonds using N -heterocyclic carbene gold(I) complexes
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A highly efficient [(NHC)AuI]-based (NHC = N-heterocyclic carbene) catalytic system for the carboxylation of aromatic and heteroaromatic C-H bonds was developed. The significant base strength of the Au-OH species is at the origin of the activation process and permits the facile functionalization of C-H bonds without the use of other organometallic reagents.
- Boogaerts, Ine I. F.,Nolan, Steven P.
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supporting information; experimental part
p. 8858 - 8859
(2010/08/21)
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- Carboxylation of N-H/C-H bonds using n-heterocyclic carbene copper(I) complexes
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Greenhouse gas makes good: A simple copper-mediated protocol has been developed where N-H or C-H bonds can be directly functionalized using an easily prepared catalyst. The novel [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] copper(I) hydroxide, [Cu(IPr)(OH)], permits the facile activation and carboxylation of N-H and C-H bonds with pKavalues of less than 27.7 (see scheme).
- Boogaerts, Ine I. F.,Fortman, George C.,Furst, Marc R. L.,Cazin, Catherine S. J.,Nolan, Steven P.
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supporting information; scheme or table
p. 8674 - 8677
(2011/01/06)
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- Fragmentation of radical anions of polyfluorinated benzoates
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A comprehensive study of the symmetry forbidden fragmentation of short-lived radical anions (RAs) has been undertaken for the complete set of polyfluorinated benzoates (C6FnH5-nCO22, n = 1-5). The decay rate constants (kc) of RAs have been determined in aqueous alkaline solution (pH 13.4) by electron photoinjection (EPI) from mercury electrodes and were found to increase dramatically from ≤3 × 103 s-1 (3-F - C6H4CO2-) to (1.2 ± 0.8) × 109 s-1 (C6F5CO2-). The regioselectivity of C-F bond cleavage in the RA fragmentation has been revealed by structure assignment of reduction products of the polyfluorinated benzoic acids by Na, K, and Zn in liquid NH3, as well as by Zn in aqueous NH3 and aqueous alkaline solutions. The kc values depend on the position of the cleaved fluorine to the CO2- group generally in the order para > ortho > meta, and to sharply increase if adjacent fluorine atoms are present. The observed trends reveal that the kinetics of the RA fragmentation reaction is not controlled by the reaction thermodynamics. Semiempirical UHF/INDO calculations, the validity of which has been confirmed by ab initio ROHF/6-31+G calculations, were done to rationalize the observed trends. The reaction transition state (TS) was considered to arise from the RA's and 2*states crossing avoided due to out-of-plane deviation of the cleaving C-F bond. The satisfactory linear correlation (R = 0.96) between the model reaction energy barrier Ea and log kc has been achieved with modeling the local solvation of the CO2- group by its protonation.
- Konovalov, Valery V.,Laev, Sergey S.,Beregovaya, Irina V.,Shchegoleva, Lyudmila N.,Shteingarts, Vitalij D.,Tsvetkov, Yuri D.,Bilkis, Itzhak
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p. 352 - 361
(2007/10/03)
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- 2,3-difluoro-6-nitrobenzonitrile and 2-chloro-5,6-difluorobenzonitrile-(2,3-difluoro-6-chlorobenzonitrile), process for their preparation and their use for the preparation of 2,3,6-trifluorobenzoic acid
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The present invention describes the novel intermediates 2,3-difluoro-6-nitrobenzonitrile and 2-chloro-5,6-difluorobenzonitrile, a process for their preparation and their advantageous use for the preparation of 2,3,6-trifluorobenzoic acid, which in turn is
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