ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Tetrabutylphosphonium 4-ethoxyvalerate as a biomass-originated media for homogeneous palladium-catalyzed Hiyama coupling reactions

László Orha, Ábrahám Papp, József M. Tukacs, László Kollár, and László T. Mika

Department of Chemical and Environmental Process Engineering, Budapest University of Technology and Economics, Budapest, Hungary

E-mail: laszlo.t.mika@mail.bme.hu

Received: 23 May 2020  Accepted: 13 July 2020

Abstract:

The introduction of a biomass-derived ionic liquid into the Hiyama coupling reactions, which has been considered as a powerful tool for the synthesis of symmetrically and non-symmetrically substituted biaryl structures, could further control or even reduce the environmental impact of this transformation. It was shown that tetrabutylphosphonium 4-ethoxyvalerate, a γ-valerolactone-based ionic liquid, can be utilized as an alternative solvent to create carbon–carbon bonds between aryl iodides and functionalized organosilanes in the presence of 1 mol% Pd under typical Hiyama conditions (130 °C, 24 h, tetrabutylammonium fluoride activator). A comparison of different ionic liquids was performed, and the effects of the catalyst precursor and the moisture content of the reaction mixture on the activity of the catalyst system were investigated. The functional group tolerance was also studied, resulting in 15 cross-coupling products (3a–o) with isolated yields of 45–72% and excellent purity (> 98%).

Keywords: Hiyama coupling; Ionic liquids; Homogeneous catalysis; Green chemistry

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-020-01287-y

Chemical Papers 74 (12) 4593–4598 (2020)