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Neutral Pd(II) complexes with Schiff-Base P^N Ligands as Suzuki-Miyaura catalysts Tebello Mahamo* 1,3,4 , Gregory S. Smith, Selwyn F. Mapolie 2 , J. Chris Slootweg 3 and Koop Lammertsma 3 1 Department of Chemistry, University of Cape Town, South Africa 2 Department of Chemistry and Polymer Science, University of Stellenbosch, South Africa 3 Department of Chemistry and Pharmaceutical Sciences, VU University Amsterdam, Amsterdam, The Netherlands 4 Department of Chemistry and Chemical Technology, National University of Lesotho, Lesotho Transition metal-catalysed C-C and C-Y (Y = heteroatom) bond forming reaction are a powerful synthetic tool in organic and organometallic chemistry. Palladium compounds form some of the most versatile and useful catalysts in these organic transformations [1,2]. Ligands with phosphorus(III) donor atoms represent the most widely used class of ligands in homogeneous catalysis due to their synthetic stability and the ease with which their properties can be modified [3]. In this study, the evaluation of a selection of easily accessible palladium(II) complexes based on N-functionalized 2-diphenylphosphinobenzaldimino ligands bearing pendant groups on the imine moiety as precatalysts in the Suzuki-Miyaura coupling reaction is presented. These complexes were found to be highly active and tolerant of a wide range of reaction conditions and functional groups on substrates. Low catalyst loadings were required, while high conversions and short reaction times were maintained. Having a substituent bearing a donor atom on the imine moiety of the ligand was found to enhance catalytic activity. Palladium methyl chloride complexes were found to be slightly more active than their palladium dichloride counterparts [4,5]. The palladium catalysts were prepared as per Scheme 1 in moderate to good yields and the catalytic reactions were carried out as outlined in Scheme 2.
Scheme 1: Synthesis of palladium (II) complexes. Scheme 1 : Synthesis of palladium (II) complexes. Scheme 1 : Synthesis of palladium (II) complexes.
© The Author(s), 2023 References: 1. M. C. D’Alterio, E. Casals -Cruañas, N. V. Tzoura, G. Talarico, S. P. Nolan and A. Poater, Chem. Eur. J ., 2021 , 27 , 13481 – 13493. 2. N. K. Sinha and N. Thiruphathi, Organometallics , 2021 , 40 , 3535 – 3549. References: 1. M. C. D’Alterio, E. Casals -Cruañas, N. V. Tzoura, G. Talarico, S. P. Nolan and A. Poater, Chem. Eur. J ., 2021 , 27 , 13481 – 13493. Scheme 2: Palladium-catalysed Suzuki-Miyaura coupling reaction. References: 1. M. C. D’Alterio, E. Casals-Cruañas, N. V. Tzoura, G. Talarico, S. P. Nolan and A.Poater, Chem. Eur. J., 2021, 27, 13481 – 13493. 2. N. K. Sinha and N. Thiruphathi, Organometallics, 2021, 40, 3535 – 3549. 3. A. R. Schaffer and J. A. R. Schmidt, Chem. Eur. J., 2009, 15, 2662 – 2673. 4. T. Mahamo, M. M. Mogorosi, J. R. Moss, S. F. Mapolie, J. C. Slootweg, K. Lammertsma and G. S. Smith, J. Organomet. Chem., 2012, 703, 34 – 42. 5. M. M. Mogorosi, T. Mahamo, J. R. Moss, S. F. Mapolie, J. C. Slootweg, K. Lammertsma and G. S. Smith, J. Organomet. Chem., 2011, 696, 3585 – 3592. Scheme 2 : Palladium-catalysed Suzuki-Miyaura coupling reaction. Scheme 2 : Palladium-catalysed Suzuki-Miyaura coupling reaction. 2. N. K. Sinha and N. Thiruphathi, Organometallics , 2021 , 40 , 3535 – 3549. 3. A. R. Schaffer and J. A. R. Schmidt, Chem. Eur. J ., 2009 , 15 , 2662 – 2673. P11
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