Organometallic cross-coupling

Campeau L-C, Rousseaux S, Fagnou K (2005) A solution to the 2-pyridyl organometallic cross-coupling problem regioselective catalytic direct arylation of pyridine V-oxides. J Am Chem Soc 127 18020-18021... 

Organometallic cross-coupling reactions provide a regiocontrolled method for the introduction of substituents to the indole ring. Palladium-catalzyed cross-coupling of 2-indolyldimethylsilanols have been utilized in the synthesis of 2-arylindoles <04OL3649>. For example, treatment of indole-2-silanol 206 and aryl iodides 207 with a palladium catalyst, copper iodide, and sodium f-butoxide provided 2-arylindoles 208. 

The synthetic routes to polyarylenes make use of the efficient aryl-aryl bond forming reactions that have been developed over the last century. These come in three categories oxidative coupling, reductive coupling, and transition-metal-mediated organometallic cross-coupling reactions (Scheme 6). Of these oxidative coupling, which is here represented by the Kovacic route to poly(para-phenylene) (PPP), is... 

Cross coupling of organometallics with organic halides catalyzed by non (ill). 

In summary, palladium-mediated reactions, especially cross-coupling reactions have found many applications in quinoline synthesis. It is noteworthy that due to the a and S activation for the C(2) and C(4) positions, even 2-chloro- and 4-chloro-quinolines are viable substrates for palladium-catalyzed reactions under standard conditions. With the advent of the palladium chemistry and more commercially available organometallic substrates, more palladium-mediated quinoline syntheses are to be added to the repertoire of quinoline chemistry. 

Knochel et al. described Pd-catalyzed Negishi cross-coupling reactions between zinc organometallics and aryl iodides in [BMMlM][Bp4]. Scheme 5.2-20 illustrates the reaction for the formation of a 3-substituted cyclohexenone from 3-iodo-2-cyclo-hexen-l-one [82]. 

Negishi E, Tan Z (2005) Diastereoselective, Enantioselective, and Regioselective Carbo-alumination Reactions Catalyzed by Zirconocene Derivatives. 8 139-176 Netherton M, Fu GC (2005)Pa]ladium-catalyzed Cross-Coupling Reactions of Unactivated Alkyl Electrophiles with Organometallic Compounds. 14 85-108 Nicolaou KC, King NP, He Y (1998) Ring-Closing Metathesis in the Synthesis of EpothUones and Polyether Natmal Products. 1 73-104 Nishiyama H (2004) Cyclopropanation with Ruthenium Catalysts. 11 81-92 Noels A, Demonceau A, Delaude L (2004) Ruthenium Promoted Catalysed Radical Processes toward Fine Chemistry. 11 155-171... 

Cross-coupling reactions resulting in C-C bond formation are normally classified according to the nature of the organometallic reagent and the organic electrophile. Scheme 6.4 summarises, broadly, the names and reaction partners of the most common of these transformations. 

These are called cross-coupling reactions and usually involve three basic steps oxidative addition, transmetallation, and reductive elimination. In the transmetallation step an organic group is transferred from the organometallic reagent to palladium. 

Scheme 8.10. Palladium-Catalyzed Cross Coupling of Organometallic Reagents with...

This method can extend Ni-catalyzed cross coupling to functionalized organometallic reagents. 

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