Metal phosphine aldehyde complexes and their application in Cu-free Sonogashira and Suzuki–Miyaura cross-coupling reactions

Abstract

Transition metal coordination chemistry and catalysis are rife with phosphine ligands. One of the rather less studied members of the phosphine ligand family are phosphine aldehydes. We have synthesised 3-(diphenylphosphino)propanal...

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

“…This could explain the formation of Pd(L1) 2 with L1 acting as a monodentate ligand with no coordination of nitrogen due to the steric hindrance introduced by the methyl group. PdL2 can also be synthesised by reaction of [PdCl 2 ( PCHO ‐κ P )] 2 [30] with 4‐(trifluoromethyl)phenylhydrazine (Supporting Information, Chapter 2).…”

“…PCHO was synthesised in a nitrogen atmosphere according to the procedure described by Vaughn and Gladysz. [30,31] The phosphino hydrazones L1-L3 were prepared by reacting PCHO with equimolar amounts of the respective hydrazine derivative, namely 1-methyl-1-phenylhydrazine (for L1), 4-(trifluoromethyl)phenylhydrazine (for L2) and 2-hydrazinylpyridine (for L3) (Scheme 1). L1 was isolated only as the E isomer.…”

“…1‐Methyl‐1‐phenylhydrazine and 2‐hydrazinylpyridine were obtained from TCI Deutschland GmbH and used as received. Dichloridobis(acetonitrile)palladium(II), [40] dichlorido(1,5‐cyclooctadiene)platinum(II) [41] and [PdCl 2 ( PCHO‐ κ P )] 2 [30] were synthesised according to the literature. NMR spectra were recorded on a Bruker Avance III HD 400 MHz NMR spectrometer at 25 °C ( 1 H 400.13 MHz, 13 C 100.63 MHz, 19 F 376.53 MHz and 31 P 162.02 MHz).…”

“…A series of heterobimetallic complexes was subsequently synthesised with a heterobimetallic Pd/Co complex showing promising catalytic activity in the sequential one‐pot Sonogashira cross‐coupling reaction followed by transfer semihydrogenation using ammonia‐borane for the synthesis of Z ‐arylalkenes [29] . Expanding the ligand family of phosphino hydrazones, we here report the synthesis of phosphino hydrazone ligands from 3‐(diphenylphosphino)propanal ( PCHO ) [30] and commercially available aryl hydrazines, their complexes with palladium(II) and platinum(II), and an insight into the catalytic activity of the palladium(II) complexes in Cu‐free Sonogashira cross‐coupling reactions.…”