Coupling, organometallic ionic liquids

In some cases, it is possible to couple an alcohol with an organometallic compound. Allylic alcohols are coupled with alkylmagnesium bromides in the presence of Ti(OiPr)4, for example. Allylic alcohols can be coupled with arylboronic acids in ionic liquid solvent and a rhodium catalyst. The palladium-catalyzed... 

The formation of unsymmetric biaryls via catalytic cross-coupling of aryl halides and organometallic compounds has been shown to proceed in ionic liquids with enhanced activity. The Suzuki-Miyaura cross coupling (cf. Section 2.11)... 

Lloyd-Williams, P., Giralt, E. Atropisomerism, biphenyls and the Suzuki coupling peptide antibiotics. Chem. Soc. Rev. 2001, 30,145-157. Dupont, J., de Souza, R. F., Suarez, P. A. Z. Ionic Liquid (Molten Salt) Phase Organometallic Catalysis. Chem. Rev. 2002, 102, 3667-3691. Hassan, J., Sevignon, M., Gozzi, C., Schulz, E., Lemaire, M. Aryl-Aryl Bond Formation One Century after the Discovery of the Ullmann Reaction. Chem. Rev. 2002, 102, 1359-1469. 

The recent advances using the relatively cheap and readily available chloroarenes in organometallic chemistry, instead of bromo or iodo-arenes, is arguably one of the most exciting developments in chemistry today [21]. A paper published in 2003 dealt with Heck couplings performed with both activated and deactivated chloroarenes in ionic liquid-doped 1,4-dioxane [145]. The coupling of butyl acrylate and 2-cMoro-m-xylene took 1 h at 180 °C when microwaves were used whereas standard heating at the same temperature required 1.5 h and resulted in a reduced yield (Scheme 15.76). 

As far as catalysis is concerned it is already benefiting from new developments such as supercritical fluids, ionic liquids, sol-gel technology, solid phase reactions, parallel and combinatorial chemistry and some of these can be coupled to microwave irradiation. Already a number of very efficient organometallic (mainly iridimn based) catalysts have been produced although we are still some way from the acid, base situation where tritia-tion (or detritiation) rates can be estimated from a knowledge of acid-base strengths. 

Calo, V., Nacci, A., Monopoli, A. et al. (2003) Pd nanoparticle catalyzed Heck arylalion of 1,1-disubstituted alkenes in ionic liquids. Study on factors affecting the regioselectivily of the coupling process. Organometallics, 22, 4193-7. 

Suzuki coupling reactions in ether-functionalized ionic liquids The importance of weakly interacting cations, Organometallics 27 (15), 3971-3977 (2008). 

Dupont et al. have reviewed ionic liquid (molten salt) phase organometallic catalysis, including the Suzuki coupling reaction [134]. 

Marsh, K.N., Boxall, J.A. lichtenthaler, R. (2004). Room Temperature Ionic Liquids and Their Mixtures, a Review, Fluid Phase EquUtb., pp. 219, 93-98 Mathews, C.J., Smith, P.J. Welton, T. (2000). Palladium Catalysed Suzuki Cross-Coupling Reactions in Ambient Temperature Ionic Liquids, Chem. Commun., 14, pp. 1249-1250 McNulty, J., Capretta, A., Wilson, J., Dyck, J., Adjabeng, G. Robertson, A. (2002). Suzuki Cross-Coupling Reactions of Aryl Halides in Phosphonium Salt Ionic Liquid imder Mild Conditions, Chem, Commun., 17, pp. 1986-1987 McLachlan, F., Mathews, C.J., Smith, P.J. Welton, T. (2003). Palladium-Catalyzed Suzuki Cross-Coupling Reactions in Ambient Temperature Ionic Liquids Evidence for the Importance of Palladium Imidazolylidene Complexes, Organometallics, 22, pp. 5350-5357... 

Iodo dimethyl amido complexes, with Ti(IV), 4, 331-332 Iodonium salts, cross-coupling with lead reagents, 9, 413 Ionic addition reactions, mechanisms, 1, 101 Ionic bis(isonitrile) complexes, liquid crystals, 12, 280 Ionic character, organometallic compound dn configuration,... 

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