- Chan-Evans-Lam C?N Coupling Promoted by a Dinuclear Positively Charged Cu(II) Complex. Catalytic Performance and Some Evidence for the Mechanism of CEL Reaction Obviating Cu(III)/Cu(I) Catalytic Cycle
-
In the present study, we report the synthesis of a series of copper(II) complexes with a wide range of ligands and their testing in the copper catalyzed Chan-Evans-Lam (CEL) coupling of aniline and phenylboronic acid. The efficiency of the coupling was directly connected with the ease of the reduction of Cu(II) to Cu(I) of the complexes. The most efficient catalyst was derived from 4-t-butyl-2,5-bis[(quinolinylimino)methyl]phenolate and two Cu(II) ions. Depending on the counter-anion nature and the concentration of the reaction mixture, the reaction can be directed to predominant C?N-bond formation. Forty-three derivatives of diphenylamine were prepared under the optimized conditions. The proposed mechanism of the catalysis was based on the reduction potential of a series of complexes, molecular weight measurements of the catalytic complex in MeOH and the kinetic studies of aniline and phenylboronic acid coupling. In addition, an 1H NMR experiment in a sealed NMR tube, without external oxygen supply available, proved that no complete Cu(II) to Cu(I) conversion was observed under the condition, ruling out the usually accepted mechanism of the C?N coupling, which included the oxygenation of the intermediately formed Cu(I) complexes after the key step of C?N conversion had already been completed. Instead, a mechanism was proposed, involving an oxygen molecule coordinated to two copper ions in the key C?N bond formation without any detectable conversion of the Cu(II) complexes to Cu(I).
- Akatyev, Nikolay,Il'in, Mikhail,Il'in, Mikhail,Peregudova, Svetlana,Peregudov, Alexander,Buyanovskaya, Anastasiya,Kudryavtsev, Kirill,Dubovik, Alexander,Grinberg, Valerij,Orlov, Victor,Pavlov, Alexander,Novikov, Valentin,Volkov, Ilya,Belokon, Yuri
-
p. 3010 - 3021
(2020/04/29)
-
- Antiviral Compounds
-
Novel compounds, methods, and compositions for treating various viral infections are described. In some embodiments the novel compounds of the invention are 3-oxo-phenothiazine derivatives; more specific embodiments include 3-oxo-phenothiazine derivatives having substituents at the 1-, 7-, and 9-positions of the phenothiazine parent ring. In other embodiments, the invention provides compositions and methods for treating viral infections, especially HIV.
- -
-
Page/Page column 14-15
(2012/09/25)
-
- Fischer indolization of ethyl pyruvate 2-[2- (trifluoromethyl)phenyl]phenylhydrazone and new insight into the mechanism of the Goldberg reaction. (Fischer indolization and its related compounds. XXVI)
-
The Fischer indolization of ethyl pyruvate 2-[2- (trifluoromethyl)phenyl]phenylhydrazone (5) gave two indolic products, ethyl 7-(trifluoromethyl)-1-phenylindole-2-carboxylate (12) as a minor product and ethyl 1-[2-(trifluoromethyl)phenyl]indole-2-carboxylate (13) as a major product. This result shows that the Fischer indolization occurred on the more electron-rich phenyl group. In the Goldberg reaction to prepare 13 from ethyl indole-2-carboxylate (15) and o- (21) or m-bromo-α,α,α-trifluorotoluene (23), it was found that Goldberg reaction proceeds via a benzyne mechanism, at least in part, in a sterically crowded situation.
- Murakami,Watanabe,Hagiwara,Akiyama,Ishii
-
p. 1281 - 1286
(2007/10/02)
-