Iron-Catalyzed C(sp2)-C(sp3) Suzuki-Miyaura Cross-Coupling Using an Alkoxide Base

Paul O. Peterson, Matthew V. Joannou, Eric M. Simmons, Steven R. Wisniewski, Junho Kim, Paul J. Chirik

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The synthesis and characterization of phenoxy(imine) iron(II) alkyl precatalysts for C(sp2)-C(sp3) Suzuki-Miyaura cross-coupling of aryl boronic esters and alkyl bromides is described. Addition of phenoxyimines (FI) to (py)2Fe(CH2SiMe3)2 (py = pyridine) afforded the high-spin iron(II) alkyl derivatives, (FI)Fe(CH2SiMe3)(py) with varying N-imine substituents. With both neopentyl glycol-protected (BNeo) and pinacol-protected boronic ester (BPin) aryl nucleophiles, an iron-catalyzed cross-coupling method was realized that utilizes mild alkoxide bases. Optimal performance was observed in nonpolar solvents with anisole and fluorobenzene identified as more benign alternatives to benzene. The scope of this transformation includes high efficiency C(sp2)-C(sp3) bond formation with both primary and secondary alkyl bromides with electron-deficient aryl and heteroaryl nucleophiles. Substrates with base-sensitive functionality including ester and nitrile groups were tolerated, highlighting the broader compatibility with an alkoxide base. Radical clock experiments support the formation of electrophile-derived radicals during catalysis, and experiments with preformed potassium aryl boronates demonstrate the role of boronate intermediates in transmetalation.

Original languageEnglish (US)
Pages (from-to)2443-2448
Number of pages6
JournalACS Catalysis
Volume13
Issue number4
DOIs
StatePublished - Feb 17 2023

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry

Keywords

  • catalysis
  • cross-coupling
  • iron
  • phenoxyimine
  • Suzuki−Miyaura

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