Development of Palladium-catalyzed cross-coupling reactions of aryl halides with organosodium and potassium compounds

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S-Block metal organyls such as organolithium or Grignard reagents are amongst the most important organometallic compounds in synthetic chemistry and are routinely employed as strong bases in deprotonation and metallation reactions. In contrast, their application in transition metal catalyzed C-C coupling reactions is less developed. This is particularly true for the more reactive (heavier) alkalimetal organyls, which more often undergo undesired sidereactions, thus reducing or even preventing product formation. Goal of the research project is the development of the direct coupling of polar organometallic compounds with aryl halides by means of palladium catalysis. Thereby, the C-C bond formation shall be realized without additional transmetallation step, thus saving expensive and toxic transmetallation reagents and the generation of salt waste. Until today, such transformations of the heavier alkali metal organyls are very limited or not feasible at all with so far existing catalysts. Thus, this limitation will be addressed by development of new catalysts based on ylide-substituted phosphines. Due to their molecular design these ligands are especially electron-rich and thus should be perfectly suited to master these transformations. Main focus will be set on potassium and sodium organyls, which have hardly been employed in coupling chemistry but offer the use of new or not yet applied nucleophiles. The developed protocol will particularly target the use of aryl chlorides due to their lower costs and broader abundance. Overall, this project will set new standards in the coupling of highly reactive polar organometallic compounds and hence close a gap in coupling and s-block metal chemistry.