Modular Synthesis of Phosphino Hydrazones and Their Use as Ligands in a Palladium-Catalysed Cu-Free Sonogashira Cross-Coupling Reaction

Phosphino hydrazones represent a versatile class of nitrogen-containing phosphine ligands. Herein, we report a modular synthesis of phosphino hydrazone ligands by hydrazone condensation reaction of three different aryl hydrazines with 3-(diphenylphosphino)propanal (PCHO). Complexation reactions of these phosphino hydrazone ligands with palladium(II) and platinum(II) were investigated and the catalytic activity of the palladium(II) complexes was explored in a Cu-free Sonogashira cross-coupling reaction achieving yields up to 96 %. Additionally it was shown that the catalytically active species is homogeneous.

Automated summary

Phosphino hydrazones are a versatile class of nitrogen-containing phosphine ligands. In this study, a modular synthesis of phosphino hydrazone ligands was achieved by condensation reactions of three different aryl hydrazines with 3-(diphenylphosphino)propanal (PCHO). The complexation reactions of these ligands with palladium(II) and platinum(II) were investigated, and the catalytic activity of the palladium(II) complexes was explored in a Cu-free Sonogashira cross-coupling reaction, achieving yields up to 96%. It was also shown that the catalytically active species is homogeneous.