ELECTRON-DEFICIENT PHOSPHINE LIGANDS FOR PALLADIUM CATALYSED C-N CROSS-COUPLING REACTIONS

Jonas Paukštys^{1, 2}, Tomas Paškevičius¹, Linas Labanauskas¹

¹ Center for Physical Sciences and Technology (FTMC)

² Vilnius Unversity

[email protected]

Arylamine moiety is widely encountered in pharmaceuticals¹ , N-ligands², herbicides and fungicides³. Palladium catalysed C-N cross-coupling reactions are often strategically used for the synthesis of such compounds. Despite extensive research in this area, the coupling of heteroaryl compounds remains a challenging task. In 2024, novel O-bound electron deficient phosphine ligands (Figure 1.) were introduced that allegedly have been shown to be resistant to deactivation by many nitrogen containing heteroaromatic compounds.⁴ Modification of steric and electronic properties of these ligands may enable chemists to include N-heteroaromatic compounds as coupling partners and thus expand the overall application scope of this reaction.

In this work, we synthesized the ligand backbones via aryne coupling reactions following iodine quench, iodinated backbones were used in further synthesis. Key step of this synthesis was the coupling of backbones with various di-substituted chlorophosphines, which were prepared from PCl₃ and desired Grignard reagent. Finally, we subjected these ligands to screening procedures to asses their catalytic performance in C-N cross coupling reactions.

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