Year 2005, Month 1 (Section Full Articles, Page 201)
Reductive electrocatalytic dehalogenation of nitrobenzyl halides:
nitrophilic or halophilic attack?
T. V. Magdesieva,(a)* O. M. Nikitin,(a) P. I. Dem´yanov,(a) M. Graczyk,(b) A. Vallat,(b) M. A. Vorotyntsev,(b) and K. P. Butin(a)
Electrochemical reduction of Cp2TiCl2 in the presence of benzylic halides results in their
catalytic dehalogenation to form toluene derivatives. Possible schemes for the process were
proposed on the basis of the results of electrochemical studies and digital simulation data. The
catalytic scheme including the halophilic attack of the TiIII complex to organic halide as a key
step occurs for unsubstituted benzylic halides. In the case of nitro-substituted substrates, the
reaction is strongly accelerated. In this case, an electron transfer from the reduced form of the
catalyst to the NO2 group of organic halide is possibly accompanied by the intramolecular
charge transfer to the Ñ—Hal bond, thus facilitating its cleavage. Thus, the nitro group in the
starting benzylic halide acts as a "redox antenna," transferring an electron to the C—Hal bond.
The proposed scheme is supported by semiempirical calculations of the geometry of molecular
complexes with the Ti—Hal or Ti—NO2 coordination.
 |
 BACK I wish to order PDF file of this article for 25.00 USD
|
ÐÓÑÑÊÀß ÂÅÐÑÈß
