Ligand-Free Suzuki–Miyaura Cross-Coupling Reactions in Deep Eutectic Solvents: A Novel Sustainable Approach Towards Bi- And Tri(Hetero)Aryl Compounds

The environmental impact associated with chemical synthesis has recently posed severe and compelling demands for sustainable chemistry. The development of cost-effective and environmentally benign reaction systems in place of volatile and harsh organic molecules represents an active field of research. In the last decade, Deep Eutectic Solvents (DESs) have emerged as new and promising alternative green reaction media. They are generally composed of two or three safe and inexpensive components, which are able to engage in hydrogen-bond interactions with each other to form an eutectic mixture with a melting point much lower than that of either of the individual components1. Building on our recently investigations on the use of organometallics in unconventional reaction media (e.g., DESs, water)2, in this Communication the effectiveness of bio-based DESs in forging new bi- and tri(hetero)aryl adducts (yields up to > 98%) by exploiting a ligand-free Suzuki-Miyaura cross-coupling reaction with either arylboronic acids or aryl potassium trifluoroborates, under mild reaction conditions (T = 60 °C) and under air, will be discussed. References: 1. a) M. Francisco, A. van den Bruinhorst, M. C. Kroon, Angew. Chem. Int. Ed., 2013, 52, 3074. b) E. L. Smith, A. Abbott, P. Ryder, Chem. Rev., 2014, 114,11060. c) J. García-Álvarez, E. Hevia, V. Capriati, Eur. J. Org. Chem. 2015, 4, 6779. d) D.A. Alonso, A. Baeza, R. Chinchilla, G. Guillena, M. Pastor, D.J. Ramón, Eur. J. Org. Chem. 2016, 4, 612. 2. a) V. Mallardo, R. Rizzi, F. C. Sassone, R. Mansueto, F. M. Perna, A. Salomone, V. Capriati, Chem. Comm., 2014, 50, 8655. b) F. C. Sassone, F. M. Perna, A. Salomone, S. Florio, V. Capriati, Chem. Comm., 2015, 51, 9459. c) L. Cicco, S. Sblendorio, R. Mansueto, F. M. Perna, A. Salomone, S. Florio, V. Capriati, Chem. Sci., 2016, 7, 1192. d) G. Dilauro, M. Dell’Aera, P. Vitale, V. Capriati, F.M. Perna, Angew. Chem. Int. Ed., 2017, 56, 10200. e) L. Cicco, M.J. Rodríguez-Álvarez, F.M. Perna, J. GarcíaÁlvarez, V. Capriati, Green Chem., 2017, 19, 3069.