Origin of Protonation Side Products in Pd-Catalyzed Decarboxylative Allylation Reactions: Evidence for In Situ Modification of Triphenylphosphine Ligand

Palladium-catalyzed decarboxylative allylation (DcA) is a well-established method of carbon-carbon bond formation. This type of coupling is quite attractive, as the only byproduct is CO2. While a wide variety of ligands have been employed with Pd(0) or Pd(II) precatalysts in DcA reactions, the ligand structure is most often based on a triarylphosphine core. Despite their demonstrated utility, DcA processes have been hindered by the formation of protonation side products. While this phenomenon has been widely acknowledged, little has been reported on the origin of the proton. Herein, we address this and provide multiple lines of experimental evidence for the proton originating from the triarylphosphine ligand. <br>

Origin of Protonation Side Products in Pd-Catalyzed Decarboxylative Allylation Reactions: Evidence for In Situ Modification of Triphenylphosphine Ligand

Palladium-catalyzed decarboxylative allylation (DcA) is a well-established method of carbon-carbon bond formation. This type of coupling is quite attractive, as the only byproduct is CO2. While a wide variety of ligands have been employed with Pd(0) or Pd(II) precatalysts in DcA reactions, the ligand structure is most often based on a triarylphosphine core. Despite their demonstrated utility, DcA processes have been hindered by the formation of protonation side products. While this phenomenon has been widely acknowledged, little has been reported on the origin of the proton. Herein, we address this and provide multiple lines of experimental evidence for the proton originating from the triarylphosphine ligand. <br>

Synthesis and Structural Studies of (h3-allyl)carbonylnitrosyl Triphenylphosphine Iron Complexes

In this paper we report the preparation of two (h3-allyl)carbonylnitrosyltriphenylphosphine iron complexes i.e.(p-allyl)carbonylnitrosyltriphenylphosphine iron (1) and (2-methyl-p-allyl) carbonylnit rosyltriphenylphosphine iron (2). These complexes (1) and (2) were prepared by reacting (p-allyl)dicarbonylnitrosyl iron and (2-methyl-p-allyl)dicarbonylnitrosyl iron with triphenylphosphine under inert atmospheric conditions. Both the resulting complexes were sufficiently and well characterized by IR, 1H NMR, 13C NMR, ESI/MS, HRMS and single crystal XRD. Triphenylphosphine ligand was found to be strong sigma donor and replaced carbonyl ligand readily. XRD revealed that the geometry of iron in both complexes is distorted octahedral.

Synthesis and Structural Studies of (h3-allyl)carbonylnitrosyl Triphenylphosphine Iron Complexes

In this paper we report the preparation of two (h3-allyl)carbonylnitrosyltriphenylphosphine iron complexes i.e.(p-allyl)carbonylnitrosyltriphenylphosphine iron (1) and (2-methyl-p-allyl) carbonylnit rosyltriphenylphosphine iron (2). These complexes (1) and (2) were prepared by reacting (p-allyl)dicarbonylnitrosyl iron and (2-methyl-p-allyl)dicarbonylnitrosyl iron with triphenylphosphine under inert atmospheric conditions. Both the resulting complexes were sufficiently and well characterized by IR, 1H NMR, 13C NMR, ESI/MS, HRMS and single crystal XRD. Triphenylphosphine ligand was found to be strong sigma donor and replaced carbonyl ligand readily. XRD revealed that the geometry of iron in both complexes is distorted octahedral.

Continuous flow hydrogenation of methyl and ethyl levulinate: an alternative route to γ -valerolactone production

Heterogeneous continuous transformation of methyl levulinate (ML) and ethyl levulinate (EL) to γ -valerolactone (GVL), as a promising C 5 -platform molecule was studied at 100°C. It was proved that the H-Cube ® continuous hydrogenation system equipped with 5% Ru/C CatCart ® is suitable for the reduction of both levulinate esters. While excellent conversion rates (greater than 99.9%) of ML and EL could be achieved in water and corresponding alcohols, the selectivities of GVL were primarily affected by the solvent used. In water, 100% conversion and ca 50% selectivity that represent ca 0.45 mol GVL g metal −1 h −1 productivity towards GVL, were obtained under 100 bar of total system pressure. The application of alcohols as a solvent, which maintained high conversion rates up to 1 ml min –1 flow rate, resulted in lower productivities (less than 0.2 mol GVL g metal −1 h −1 ) of GVL. Therefore, from a synthesis point of view, the corresponding 4-hydroxyvalerate esters could be obtained even at a higher reaction rate. The addition of sulfonated triphenylphosphine ligand (TPPTS) allowed reduction of the system pressure and resulted in the higher selectivity towards GVL.

Hydrochlorination of acetylene catalyzed by an activated carbon supported chlorotriphenylphosphine gold complex

The presence of triphenylphosphine ligand inhibits the agglomeration of gold particles during acetylene hydrochlorination, thereby improving the catalytic performance of the Au-based catalyst.

New aryloxybenzylidene ruthenium chelates – synthesis, reactivity and catalytic performance in ROMP

New phenoxybenzylidene ruthenium chelates were synthesised from the second generation Grubbs catalysts bearing a triphenylphosphine ligand (or its para-substituted analogues) by metathesis exchange with substituted 2-vinylphenols. The complexes behave like a latent catalyst and are characterized by an improved catalytic behaviour as compared to that of the known analogues, i.e., they exhibit high catalytic inactivity in their dormant forms and a profound increase in activity after activation with HCl. The strong electronic influence of substituents in the chelating ligand on the catalytic activity was demonstrated. The catalytic properties were tested in ROMP of cyclooctadien (COD) and a single selected norbornene derivative.