Synthesis of biphenyl-based arsine ligands by microwave assisted Suzuki-Miyaura coupling and their applications

GISELA J. QUINTEROS; SANDRA E. MARTÍN

Blucher Chemistry Proceedings

Editora Blucher

Año: 2011 vol. 1 p. 162 - 162

2318-4043

Synthesis of biphenyl-based arsine ligands by microwaveassisted Suzuki-Miyaura coupling and their applications Gisela J. Quinteros, Sandra E. Martín* INFIQC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000-Córdoba, Argentina *e-mail martins@fcq.unc.edu.ar Keywords: arsine ligands, Suzuki-Miyaura, microwave INTRODUCTION Over the past few years, there has been a growing interest in the synthesis and application of biphenylbased monophosphine ligands.1 Although tertiary phosphines constitute the group of ligands most widely used in metal-catalyzed reactions, arsines have been shown to be excellent ligands and there are several examples where arsine complexes give more active or selective catalysts than phosphines. We have developed a versatile methodology that allow for C-As bond formation through a Pdcatalyzed arsination with stannane n-Bu3SnAsPh2. 2 By this methodology we carried out the synthesis of a novel biphenylarsine ligand biphenyl-2- yldiphenylarsine, and also the preliminary investigation of its performance as a ligand.2a Herein, we report the synthesis of a family of biarylarsine ligands (Figure 1) by an approach, including first the Pd-catalyzed arsination, and then the microwave-assisted Suzuki-Miyaura coupling as the key synthetic tool for biaryl construction. Additionally, the activity of new biarylarsine ligands in Pd-catalyzed reactions is also reported. RESULTS AND DISCUSSION By the Pd-catalyzed arsination with n-Bu3SnAsPh2 (1), the (2-bromophenyl)diphenylarsine (2, 83%) was obtained.2a The Suzuki-Miyaura coupling reaction between bromoarsine 2 and aryl boronic acids bearing different substituents provided biarylarsine ligands L1-L9 in very good (66-99%) (Scheme 1). Scheme1. Insert the figure caption her The coupling reaction conditions were thoroughly optimized, and we explored different methods and system for MW irradiation. Figure1. Insert the figure caption her Despite of the considerably bulky -AsPh2 moiety in 2 and boronic acids with two groups in the ortho positions, the reaction was successfully carried out. The efficiency of catalysts derived from the new biarylarsine ligands was evaluated in Pd-catalyzed Stille and Heck. The Pd/L4 and L6 based catalysts demonstrated significant activity for both coupling reactions with 4-bromoanisol. CONCLUSION We have synthesized a new family of biarylarsine ligands with different steric and electronic properties, varying the substituents in the biaryl backbone. Our newly prepared biphenylarsine ligands show promised activity for Pd-catalyzed reactions. ACKNOWLEDGEMENTS We are grateful to ACC, CONICET, FONCYT and SECYTUNC for financial support. REFERENCES 1 (a) Martin, R.; Buchwald, S. L. Acc. Chem. Res. 2008, 41, 1461. (b) Fu, G. C. Acc. Chem. Res. 2008, 41, 1555. 2 (a) Bonaterra, M.; Martín, S. E.; Rossi, R. A. Org. Lett. 2003, 5, 2731. (b) Uberman, P. M.; Lanteri, M. N; Martín, S. E. Organometallics 2009, 28, 6927.