A modular design of metal catalysts for the transfer hydrogenation of aromatic ketones

Abstract

The ability of transition metal catalysts to add or remove hydrogen from organic substrates by transfer hydrogenation is a valuable synthetic tool. Towards a series of novel metal complexes with a P-NH ligand, [ ) for the transfer hydrogenation reaction in comparison to analogous rhodium or iridium complexes.

Amidophosphine‐stabilized palladium complexes catalyse Suzuki–Miyaura cross‐couplings in aqueous media

“…The 31 P NMR spectra of 3 and 4 show a signal at 61.8 ppm ( 3 ) and 69.9 ppm ( 4 ) that is shifted downfield compared to starting phosphines L 3 PPh 2 (45.5 ppm) and L 3 PPh(tBu) (54.9 ppm). The 31 P NMR signal found for 3 is similar to that of its cis ‐isomer cis ‐{L 3 PPh 2 } 2 PdCl 2 (64.1 ppm) .…”

“…The 31 P NMR spectra of 3 and 4 show a signal at 61.8 ppm ( 3 ) and 69.9 ppm ( 4 ) that is shifted downfield compared to starting phosphines L 3 PPh 2 (45.5 ppm) and L 3 PPh(tBu) (54.9 ppm). The 31 P NMR signal found for 3 is similar to that of its cis ‐isomer cis ‐{L 3 PPh 2 } 2 PdCl 2 (64.1 ppm) . The 1 H NMR spectra of 3 and 4 show the presence of four doublets at 0.88, 1.03, 1.23 and 1.34 ppm of C H 3 groups of ligand L 3 in 3 (1.01, 1.16, 1.23 and 1.46 ppm for 4 ) and two septets of C H groups at 3.24 and 3.43 ppm in 3 (3.81 and 3.86 ppm in 4 ).…”

“…Complexes 3 and 4 , obtained by the reaction of PdCl 2 with L 3 PPh 2 and L 3 PPh( t Bu) (Scheme ) were prepared to study the effect of the steric shielding of the phosphorus atom on the catalytic activity. It is worth mentioning that cis ‐{L 3 PPh 2 } 2 PdCl 2 has already been prepared by the reaction of L 3 PPh 2 with (cod)PdCl 2 , but the structure of the complex has not been determined so far.…”

“…Recently, Baysal and co‐workers reported the synthesis of cis ‐{L 3 PPh 2 } 2 PdCl 2 , where L 3 is (2,6‐iPr 2 (C 6 H 3 )NH) − (Fig. ), and showed its suitability for Suzuki–Miyaura cross‐coupling reactions . Ligand L 3 with NH moiety and similarly the presence of the NMe 2 functional group in 1 could be suitable for two‐phase system extraction, while 2 contains O t Bu group that may render the complex soluble in water.…”

Applications of transition metal complexes containing 3,3′-bis(diphenylphosphinoamine)-2,2′-bipyridine ligand to transfer hydrogenation of ketones

“…Ligands containing direct phosphorusenitrogen bonds are quite attractive as structural modifications can be introduced via simple PeN bond formation [15] and they have proved to be versatile ligands, and varying the substituents on both P-and N-centers gives rise the changes in the PeNH angle and to conformation around the P-centers [16]. Small variations in these ligands can cause significant changes in their coordination behavior and the structural features of the resulting complexes [17,18]. The use of tertiary phosphines is widespread in organometallic chemistry and in homogeneous catalysis as these ligands can be used to fine tune the metal reactivity and selectivity.…”