Identification of a Surprising Boronic Acid Homocoupling Process in Suzuki–Miyaura Cross-Coupling Reactions Utilizing a Hindered Fluorinated Arene

Dedicated to Professor Barry Trost in honor of his 80^th birthday.

Abstract

The Suzuki–Miyaura cross-coupling reaction of 2-bromo-1,3-bis(trifluoromethyl)benzene with arylboronic acids was evaluated and determined to suffer from the formation of large amounts of boronic acid homocoupling products in conjunction with dehalogenation. Homocoupling product formation in this process likely occurs through a rare protonolysis/second transmetalation event rather than by the well-established mechanism requiring the involvement of O₂. The scope of this boronic acid homocoupling reaction was investigated and shown to predominate with electron-deficient arylboronic acids. Finally, a good yield of cross-coupling products could be obtained by employing dicyclohexyl(2′,6′-dimethoxybiphenyl-2-yl)phosphine (SPhos) as the ligand.

Key words

palladium catalysis - Suzuki–Miyaura reaction - cross-coupling - arylboronic acids - bromobistrifluoromethylbenzene

Publication History

Received: 16 July 2020

Accepted after revision: 03 August 2020

Article published online:
27 August 2020

• References and Notes


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