Base-free cross-couplings of aryl diazonium salts in methanol: PdII–alkoxy as reactivity-controlling intermediate

Italo A. Sanhueza, Felix J. R. Klauck, Erdem Senol, Sinead T. Keaveney, Theresa Sperger, Franziska Schoenebeck*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Pd-catalyzed cross-coupling reactions of aryl diazonium salts are generally assumed to proceed via cationic PdII intermediates which in turn would be highly reactive in the subsequent transmetalation step. Contrary to this belief, we herein report our observation and rationalization of opposing reactivities of ArN2+ in Suzuki (=effective) and Stille (=ineffective) cross-couplings in MeOH. Our systematic experimental and computational studies on the roles of transmetalating agent, solvent, base and the likely involvement of in situ formed diazoether derivatives challenge the currently accepted mechanism. Our data suggest that the observed solvent dichotomy is primarily due to PdII-methoxy intermediates being formed, which are unreactive with arylstannanes, but highly reactive with arylboronic acids, complementing the Suzuki “Pd-oxy” mechanism with the direct demonstration of transmetalation of a PdII-alkoxy complex. Lewis acids were found to circumvent this reactivity divergence, promoting efficient couplings regardless of the employed conditions or coupling partners.

Original languageEnglish
Pages (from-to)7007-7012
Number of pages6
JournalAngewandte Chemie - International Edition
Volume60
Issue number13
DOIs
Publication statusPublished - 22 Mar 2021
Externally publishedYes

Keywords

  • computation
  • cross-coupling
  • diazonium salts
  • reaction mechanism
  • solvent dependence
  • transmetalation

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