100713-10-8Relevant academic research and scientific papers
Highly electron-poor Buchwald-type ligand: application for Pd-catalysed direct arylation of thiophene derivatives and theoretical consideration of the secondary Pd0-arene interaction
Korenaga, Toshinobu,Sasaki, Ryo,Shimada, Kazuaki
, p. 19642 - 19650 (2015/11/27)
Highly electron-poor SPhos ligands bearing either 2,6-bis(trifluoromethyl)-4-pyridyl (BFPy) or 3,5-(CF3)2C6H3 groups were synthesised. The former ligand highly accelerated the Pd-catalysed direct arylation of 2-propylthiophene, 2-methylthiophene or benzo[b]thiophene with only 1 mol% of the catalyst. This high catalytic activity can be attributed to a combination of electronic properties and the secondary Pd-arene interaction of BFPySPhos. The secondary interactions of SPhos, PhSPhos and BFPySPhos were optimised at the oniom(mp2/lanl2dz: b3lyp/lanl2dz) level and were further evaluated using the NBO method by DFT at the M06-2X/6-31G(d) level with LanL2DZ + ECP. The deletion energy analysis showed that the transfer of electrons from Pd to aromatic ring is the dominating factor for the secondary Pd-arene interaction of SPhos-Pd0 complexes. Although an electron-poor BFPySPhos does not particularly favour this type of interaction, this interaction is still substantial enough to sufficiently stabilise the BFPySPhos-Pd complex.
