Iminophosphine–palladium(0) complexes as highly active catalysts in the Suzuki reaction. Synthesis of undecaaryl substituted corroles

Abstract

Abstract-The iminophosphine-palladium(0) complex [Pd(dmfu)(P-N)] [dmfu ¼ dimethyl fumarate; P-N ¼ 2-(PPh 2 )C 6 H 4 -1-CH@NC 6 H 4 -4-OMe] is a very efficient catalyst for the Suzuki coupling. In the reaction of aryl bromides with phenylboronic acid, turnover numbers up to ca. 200,000 are obtained at 110°C in 2 h. Good rates are obtained also with the sterically hindered and electronically deactivated 2-bromo-1,3,5-trimethylbenzene. The complex is able to catalyze the exhaustive arylation of 2, 3,7,8,12,13,17,10, to yield the corresponding undecaaryl substituted derivative.

Corrole: The Little Big Porphyrinoid

“…Fully brominated copper complex 45 underwent a Suzuki cross-coupling reaction with a boronic acid to give (undecaarylcorrole)copper complex 46, 46 which was successfully demetalated to give the corresponding free base 47. The related reaction pathway is shown in Scheme 12.…”

Orbital Interaction and Electron Density Transfer in PdII([9]aneB2A)L2 Complexes: Theoretical Approaches

“…In this context, the achievements in development of novel and efficient synthetic methodologies for these types of reactions have been acknowledged with the 2010 Nobel Prize in Chemistry. Much attention has been paid to the design and development of powerful Pd-catalysts/precursors [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,37,38,39,40,41,42,43] that contain bulky and electron-rich ligands (such as phosphines and N -heterocyclic carbenes, NHCs) and to their potential synthetic applications [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36] in the Pd-catalyzed cross-couplings of various substrates (such as allyl, aryl, and vinyl halides and olefins). Catalytic activity enhancement of Pd (0) ( L ) n -precursors is greatly influenced by the electronic and steric properties of electron-rich and bulky L- ligands [1,2,3,4,5,6,7,8,18,19,20,21,22,23,24…”

“…The geometric structures of the active RPd( L ) n X intermediates produced in various steps of Pd-mediated cross-coupling reactions (e.g., oxidative addition, transmetalation, reductive elimination) have been investigated both theoretically [9,10,11,12,13,14,15,16,17] and experimentally [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42]. The oxidative addition of substrates (R-X) to Pd L n -precursor resulted in penta-, hexa-, and octacoordinate geometries [33,34,35,36] of the RPd II ( L ) n X intermediates with relative stability and a life time of 30 s [3].…”

Mechanistic study on the coupling reaction of aryl bromides with arylboronic acids catalyzed by (iminophosphine)palladium(0) complexes. Detection of a palladium(ii) intermediate with a coordinated boron anion

“…6 With a suitable choice of the reaction conditions, an almost complete conversion of the substrates to biaryls can be obtained also when deactivating groups are present on the aryl bromide. These results prompted us to carry out a mechanistic investigation of the fundamental steps of the catalytic cycle of Scheme 1 in order to achieve a better understanding of (i) the factors which affect the reaction rates and (ii) the mechanism of the transmetallation step, because the formation of the anion Ar 1 B(OH) 3 − or the complex [Pd(OR)(Ar)(L) 2 ] can hardly occur under the catalysis conditions used.…”