Iron-Catalyzed C(sp²)–C(sp³) Cross-Coupling of Aryl Chlorobenzoates with Alkyl Grignard Reagents

Abstract

Aryl benzoates are compounds of high importance in organic synthesis. Herein, we report the iron-catalyzed C(sp2)−C(sp3) Kumada cross-coupling of aryl chlorobenzoates with alkyl Grignard reagents. The method is characterized by the use of environmentally benign and sustainable iron salts for cross-coupling in the catalytic system, employing benign urea ligands in the place of reprotoxic NMP (NMP = N-methyl-2-pyrrolidone). It is notable that high selectivity for the cross-coupling is achieved in the presence of hydrolytically-labile and prone to nucleophilic addition phenolic ester C(acyl)−O bonds. The reaction provides access to alkyl-functionalized aryl benzoates. The examination of various O-coordinating ligands demonstrates the high activity of urea ligands in promoting the cross-coupling versus nucleophilic addition to the ester C(acyl)−O bond. The method showcases the functional group tolerance of iron-catalyzed Kumada cross-couplings.

Keywords

• iron
• cross-coupling
• aryl esters
• c–o activation
• fe-catalysis
• kumada cross-coupling