Asymmetric transfer hydrogenation of acetophenone derivatives using 2-benzyl-tethered ruthenium (II)/TsDPEN complexes bearing η6-(p-OR) (R = H, iPr, Bn, Ph) ligands

A series of 4′-OR (R = H, iPr, Bn, Ph) substituted ruthenium (II) biphenyl TsDPEN complexes are described; the complexes are accessed via an operationally simple and reliable two-step ligand synthesis followed by ligation to the ruthenium (II) centre. We report the preliminary asymmetric transfer hydrogenation (ATH) results on a range of primarily acetophenone derivatives with these new complexes using FA/TEA (5:2) as a reducing agent; the results confirm that these catalysts are capable of reducing the substrates within 48 h with excellent enantioselectivities

Synthesis ofN,N′-Disubstituted Urea from Ethylene Carbonate and Amine Using CaO

Calcium oxide has been proved to be an excellent solid catalyst for the synthesis of N,N′-disubstituted ureas from ethylene carbonate and primary amines under mild conditions

<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language:AR-SA" lang="EN-GB">Chitosan biohydrogel beads: A recyclable, biodegradable, heterogeneous catalyst for the regioselective synthesis of 5-aryl-2-oxazolidinones from carbon dioxide and aziridines at mild conditions</span>

1354-1360<span style="mso-bidi-font-size:9.0pt;color:black; letter-spacing:-.1pt" lang="EN-GB">In the search for efficient catalysts for a reaction under mild conditions, c<span style="mso-bidi-font-size:9.0pt; letter-spacing:-.1pt" lang="EN-GB">ycloaddition reactions of carbon dioxide with various aziridines catalyzed by chitosan biohydrogel beads without additional solvent and metal co-catalyst to form five-membered 5-aryl-2-oxazolidinones in high yields and selectivity has been studied. Reaction rate, conversion and selectivity are studied as a function of a series of input variables including catalyst loading, temperature, pressure and solvent system. The catalyst is easily recovered and has been reused in five consecutive cycles without any significant loss of its catalytic activity and selectivity. The catalyst, chitosan biohydrogel beads, has been characterized by a variety of techniques, namely, scanning electron microscopy and Fourier transform infrared spectroscopy. A plausible reaction mechanism for the hydrogen-bond assisted ring-opening of aziridine to five-membered 5-aryl-2-oxazolidinones is also proposed. </span

Aminophosphine Palladium Pincer-Catalyzed Carbonylative Sonogashira and Suzuki–Miyaura Cross-Coupling with High Catalytic Turnovers

This work documents the first palladium pincer complex-catalyzed carbonylative Sonogashira (CS) and carbonylative Suzuki–Miyaura (CSM) cross-coupling. Compared to previous protocols, which employ hazardous and toxic solvents, the aminophosphine pincer complex {[C6H3-2,6-(NHP­{piperidinyl}2)2]­Pd­(Cl)} (III) catalyzes both the cross-coupling reactions in propylene carbonate, an eco-friendly and sustainable polar aprotic solvent. Advantageously, employing III allows the CS cross-coupling to be carried out at a palladium loading of 10–4 mol % and the CSM cross-coupling to be carried out at 10–6 mol %, thus resulting in catalytic turnovers of 105 and 107, respectively. Relative comparison of the pincer complex with conventional palladium precursors Pd­(OAc)2 and PdCl2(PPh3)2 shows the efficiency and robustness of the pincer complex in effecting higher catalytic activity at low palladium loadings

Synthesis of Ethylene Glycol from Syngas via Oxidative Double Carbonylation of Ethanol to Diethyl Oxalate and Its Subsequent Hydrogenation

This work reports a novel sustainable two-step method for the synthesis of ethylene glycol (EG) using syngas. In the first step, diethyl oxalate was selectively synthesized via oxidative double carbonylation of ethanol and carbon monoxide (CO) using a ligand-free, recyclable Pd/C catalyst. In the second step, the diethyl oxalate produced underwent subsequent hydrogenation using [2-(di-tert-butylphosphinomethyl)-6-(diethylaminomethyl)­pyridine]­ruthenium­(II) chlorocarbonyl hydride to get EG and ethanol. Thus, the generated ethanol can be recycled back to the first step for double carbonylation. This method gives a sustainable route to manufacture EG using carbon monoxide and hydrogen

Selective Hydrogenation of Phenylacetylene with Graphite Intercalated Platinum Nanosheets

Platinum nanosheets between graphite layers were active for hydrogenation of ethynyl group of phenylacetylene but less active for that of aromatic rings of phenylacetylene and benzene due to its structural characteristics