72491-19-1Relevant academic research and scientific papers
Phosphine-free pincer-ruthenium catalyzed biofuel production: High rates, yields and turnovers of solventless alcohol alkylation
Das, Babulal,Das, Kanu,Kumar, Akshai,Srivastava, Hemant Kumar,Yasmin, Eileen
, p. 8347 - 8358 (2020/12/31)
Phosphine-free pincer-ruthenium carbonyl complexes based on bis(imino)pyridine and 2,6-bis(benzimidazole-2-yl) pyridine ligands have been synthesized. For the β-alkylation of 1-phenyl ethanol with benzyl alcohol at 140 °C under solvent-free conditions, (Cy2NNN)RuCl2(CO) (0.00025 mol%) in combination with NaOH (2.5 mol%) was highly efficient (ca. 93% yield, 372?000 TON at 12?000 TO h-1). These are the highest reported values hitherto for a ruthenium based catalyst. The β-alkylation of various alcohol combinations was accomplished with ease which culminated to give 380?000 TON at 19?000 TO h-1 for the β-alkylation of 1-phenyl ethanol with 3-methoxy benzyl alcohol. DFT studies were complementary to mechanistic studies and indicate the β-hydride elimination step involving the extrusion of acetophenone to be the overall RDS. While the hydrogenation step is favored for the formation of α-alkylated ketone, the alcoholysis step is preferred for the formation of β-alkylated alcohol. The studies were extended for the upgradation of ethanol to biofuels. Among the pincer-ruthenium complexes based on bis(imino)pyridine, (Cy2NNN)RuCl2(CO) provided high productivity (335 TON at 170 TO h-1). Sterically more open pincer-ruthenium complexes such as (Bim2NNN)RuCl2(CO) based on the 2,6-bis(benzimidazole-2-yl) pyridine ligand demonstrated better reactivity and gave not only good ethanol conversion (ca. 58%) but also high turnovers (ca. 2100) with a good rate (ca. 710 TO h-1). Kinetic studies indicate first order dependence on concentration of both the catalyst and ethanol. Phosphine-free catalytic systems operating with unprecedented activity at a very low base loading to couple lower alcohols to higher alcohols of fuel and pharmaceutical importance are the salient features of this report. This journal is
Stereoselective alcohol silylation by dehydrogenative Si-O coupling: Scope, limitations, and mechanism of the Cu-H-catalyzed non-enzymatic kinetic resolution with silicon-stereogenic silanes
Rendler, Sebastian,Plefka, Oliver,Karatas, Betuel,Auer, Gertrud,Froehlich, Roland,Mueck-Lichtenfeld, Christian,Grimme, Stefan,Oestreich, Martin
supporting information; experimental part, p. 11512 - 11528 (2009/12/07)
Ligand-stabilized copper(I)hydride catalyzes the dehydrogenative Si-O coupling of alcohols and silanes-a process that was found to proceed without racemization at the silicon atom if asymmetrically substituted. The present investigation starts from this pivotal observation since silicon-stereogenic silanes are thereby suitable for the reagent-controlled kinetic resolution of racemic alcohols, in which asymmetry at the silicon atom enables discrimination of enantiomeric alcohols. In this full account, we summarizeour efforts to systematically examine this unusual strategy of diastereoselective alcohol silylation. Ligand (sufficient reactivity with moderately electron-rich monophosphines), silane (reasonable diastereocontrol with cyclic silanes having a distinct substitution pattern) as well as substrate identification (chelating donor as a requirement) areintroductorily described. With these basic data at hand, the substrate scope was defined employing enantiomerically enriched tert-butyl-substituted 1-silatetraline and highly reactive 1-si-laindane. The synthetic part is complemented by the determination of the stereochemical course at the silicon atom in the Si-O coupling step followed by its quantum-chemical analysis thus providing a solid mechanistic picture of this remarkable transformation.
Lanthanide complexes in organic synthesis: Selective NaBH4 reduction of α,β-unsaturated carbonyl compounds
Swamy, S. Jagannatha,Kumar, B. Kishore
, p. 484 - 486 (2007/10/03)
The anhydrous lanthanide(III) complexes of N, N'-ethylene-bis(2-aminobenzamide) and N,N'-propylene-bis (2-aminobenzamide) catalyze the sodium borohydride reduction of α, β-unsaturated carbonyl compounds very selectively under ambient conditions. The heavier lanthanide complexes give good yields as compared to their hydrated chloride salts.
Direct Coupling of Functionalized Organolithium Compounds with Aryl and Vinyl Halides
Barluenga, Jose,Montserrat, Javier M.,Florez, Josefa
, p. 5976 - 5980 (2007/10/02)
The reaction between β- and γ-nitrogen-functionalized and γ- and ε-oxygen-functionalized organolithium compounds 3, 4, 30-32 and different aromatic, heteroaromatic, and vinylic halides affords directly the corresponding substitution products: functionalized benzamides 5-26 and alcohols 33-37.Symmetrical and mixed products of double coupling 38-40 were also prepared from 1,4-diiodobenzene.The formation of alkyl halides as intermediates has been verified.Aryl or vinyl halides giving rise to unstable aryl or vinyllithium reagents were unsuccessful in the coupling reaction.
