Rhodium complexes arene

Vigalok A, Uzan O, Shimon LJW, Ben-David Y, Martin JML, Milstein D (1998) Formation of r]2 C-H agostic rhodium arene complexes and their relevance to electrophilic bond activation. J Am Chem Soc 120 12539-12544... 

James et al. reported a case of product inhibition in the Rh-catalyzed enantioselective hydrogenation of N-phenyl benzaldehyde imine [37]. These authors were able to isolate the deactivated catalyst, and to obtain its X-ray structure, which showed, surprisingly, that it was a rhodium complex with the product bound through a rf-n-axene interaction (Scheme 44.5). More cases of inhibition via formation of metal arene complexes will be detailed in Section 44.5. 

Rhodium(I) complexes with l,3-dimethylimidazolin-2-ylidene ligands were used in the hydroformylation of olefins. However, the activity and selectivity toward formation of branched versus linear aldehyde cannot compete with rhodium-phosphine systems. " Similar catalyst systems with the sterically more demanding l,3-dimesitylimidazolin-2-ylidene give higher branched/linear ratios for vinyl arenes (95 5), but the turnover frequency is still low compared to established systems [Eq. (52)]. ... 

Arene complexes of rhodium have also been proven to be effective pre-catalysts for the [5+2] reaction [30]. We had previously shown that intramolecular diene-alkyne (and... 

So far as we know, this approach has been used only once, although it should be capable of extension. The octahedrally coordinated rhodiacyclopentadiene complex 94, which results from the reaction of [RhCl(PPh3)3] with 2 mol of (2-phenyl-ethynyl)diphenylphosphine, reacts with diphenylacetylene to give the di-strapped arene-rhodium(I) complex 95, from which the p-terphenyl-based bis (diphenylphosphine) can be released by heating with NaCN [Eq. (19)].84... 

C-M bond addition, for C-C bond formation, 10, 403-491 iridium additions, 10, 456 nickel additions, 10, 463 niobium additions, 10, 427 osmium additions, 10, 445 palladium additions, 10, 468 rhodium additions, 10, 455 ruthenium additions, 10, 444 Sc and Y additions, 10, 405 tantalum additions, 10, 429 titanium additions, 10, 421 vanadium additions, 10, 426 zirconium additions, 10, 424 Carbon-oxygen bond formation via alkyne hydration, 10, 678 for aryl and alkenyl ethers, 10, 650 via cobalt-mediated propargylic etherification, 10, 665 Cu-mediated, with borons, 9, 219 cycloetherification, 10, 673 etherification, 10, 669, 10, 685 via hydro- and alkylative alkoxylation, 10, 683 via inter- andd intramolecular hydroalkoxylation, 10, 672 via metal vinylidenes, 10, 676 via SnI and S Z processes, 10, 684 via transition metal rc-arene complexes, 10, 685 via transition metal-mediated etherification, overview,... 

A variety of transition metals, for example, chromium, molybdenum, tungsten, iron, vanadium, manganese, and rhodium can be used to prepare relatively stable j -arene complexes (see Arene Complexes). Reactions of j -arene chromium tricarbonyl complexes have been extensively examined, and numerous reviews are available. Although chromium complexes are by far the most utilized in organic synthesis, complexes of iron and manganese are emerging as potentially useful alternatives. 

Electron-deficient rhodium(III) complexes participate in the electrophilic metalation of arenes, as originally shown by Aoyama, Ogoshi, and co-workers [60,61], Highly electrophilic rhodium(III) complexes have also been employed in other reactions that involve the C-H functionalization of arenes, such as the carboxylation of... 

Aoyama Y, Yoshida T, Sakurai K-i, Ogoshi H (1983) Activation of arene carbon-hydrogen bonds. Direct electrophilic aromatic metalation with a rhodium-porphyrin complex. J Chem Soc Chem Commun 478-479... 

---