from first principles PP-I-1

PP-II-10Metal Depended Regioselectivity in Carbonylation of SubstitutedHalobenzenesKhaibulova T.S. 1 , Zhesko T.E. 2 , Boyarskiy V.P. 11 Chemistry Department, St. Petersburg State University, St. Petersburg, Russia2 «VNIINephtechim», St. Petersburg, Russiataniaxria@yandex.ruCarbonylation of aryl halides is an example of transition metals catalyzed C-C bondformation. Pd and Co complexes are the main carbonylation catalysts. There is a general stagefor these reactions: an activation of an aryl halide with a transition metal complex (OxAdd),which usually is a key step in the catalytic cycle and determines the reaction rate. This is thestage responsible for what will whether the catalyst activate one or another organic substrate.We have examined the selectivity of substituted halobenzenes carbonylation catalyzed byCo- and Pd-complexes. It turned out that the influence of electronic factors in the substrateand the nature of the halogen on the reactivity is the same for both catalyst systems. At thesame time, the steric factor manifests itself differently in these two processes. Substituents inthe ortho-position to the reaction centre, as a rule, slow the carbonylation catalysed byPd-complexes. In the case of cobalt catalyst the sign of the steric effect changes, and thecarbonylation of substituted bromo- and chlorobenzenes is accelerated as the donor andacceptor substituents are in the ortho-position to the reaction centre.This dependence of the ortho-effect sign from the metal nature can be explained within theconcept of several possible ways to activate a halide. A key step of the cobalt-catalyzedcarbonylation is radical anion non-chain activation of the aryl halide with an anion cobaltcomplex. In the case of the Pd-catalyzed carbonylation the activation of the aryl halideprocesses via a concerted mechanism (OxIns). A possibility of the selective synthesisortho- or para-substituted benzoic acid by the Co- or the Pd-catalyzed reaction, respectively,is due to this difference.The authors thank Saint-Petersburg State University for a research grant, the Federal TargetedProgram “Scientific and Scientific-Pedagogical Personnel of the Innovative Russia in2009–2013” (contract P676 from 20/05/2010), and RFBR (grant 11-03-00048-а).References:[1] Boyarskii, V. P.; Larionov, E. V.; Polyakova, S. M.; Boyarskaya, I. A.; Zhesko, T. E. Russ.J. Gen.Chem. 77 (2007) 915.141