1197-07-5Relevant academic research and scientific papers
Ring-opening of epoxides promoted by organomolybdenum complexes of the type [(η5-C5H4R)Mo(CO)2(η3-C3H5)] and [(η5-C5H5)Mo(CO)3(CH2R)]
Bruno, Sofia M.,Gomes, Ana C.,Abrantes, Marta,Valente, Anabela A.,Pillinger, Martyn,Gon?alves, Isabel S.
, p. 179 - 183 (2015)
The cyclopentadienyl molybdenum carbonyl complexes [(η5-C5H4R)Mo(CO)2(η3-C3H5)] and [(η5-C5H5)Mo(CO)3(CH2R)] (R = H, COOH) have been shown to promote acid-catalysed reactions in liquid phase, under moderate conditions. The catalytic alcoholysis of styrene oxide with ethanol at 35 °C gave 2-ethoxy-2-phenylethanol in 100% yield within 30 min for the dicarbonyl complexes and 3-6 h for the tricarbonyl complexes. Steady catalytic performances were observed in consecutive runs with the same catalytic solution, suggesting fairly good catalytic stability. In the second acid-catalysed reaction studied, the isomerization of α-pinene oxide at 55 °C gave campholenic aldehyde and trans-carveol in a total yield of up to 86% at 100% conversion. Chemoselectivity is shown to be solvent dependent.
Isomerization of α-pinene oxide using Fe-supported catalysts: Selective synthesis of campholenic aldehyde
Stekrova, Martina,Kumar, Narendra,Aho, Atte,Sinev, Ilia,Grünert, Wolfgang,Dahl, Johnny,Roine, Jorma,Arzumanov, Sergey S.,M?ki-Arvela, P?ivi,Murzin, Dmitry Yu.
, p. 162 - 176 (2014)
α-Pinene oxide, an oxygenated derivative of α-pinene, can be converted into various valuable substances useful as flavour, fragrance and pharmaceutical compounds. Campholenic aldehyde is one of the most desired products of α-pinene oxide isomerization being a valuable intermediate for the production of sandalwood-like fragrances. Iron modified zeolites Beta-75 and ZSM-5, mesoporous material MCM-41, silica and alumina were prepared by two methods (impregnation and solid-state ion exchange) and tested for selective preparation of campholenic aldehyde by isomerization of α-pinene oxide. The characterization of tested catalyst was carried out using scanning electron microscope analysis, nitrogen adsorption measurements, pyridine adsorption-desorption with FTIR, X-ray absorption spectroscopy measurements, XPS-analysis, 29Si MAS NMR and 27Al MAS NMR and X-ray diffraction. The isomerization of α-pinene oxide was carried out in toluene as a solvent at 70 C. The main properties influencing the activity and the selectivity are the acidic and structural properties of the tested catalysts. The highest selectivity of 66% was achieved at complete conversion of α-pinene oxide with Fe-MCM-41.
Vanadium-containing nickel phosphate molecular sieves as catalysts for α-pinene oxidation with molecular oxygen: A study of the effect of vanadium content on activity and selectivity
Timofeeva, M. N.,Panchenko, V. N.,Prosvirin, I. P.,Hasan, Zubair,Jhung, Sung Hwa
, p. 328 - 334,7 (2012)
Vanadium-containing nickel phosphate molecular sieves (V-VSB-5) were applied as heterogeneous catalysts for the liquid phase oxidation of α-pinene with molecular oxygen at 60 °C. It has been found that the vanadium content in V-VSB-5 materials affects the
Tailoring Lewis/Br?nsted acid properties of MOF nodesviahydrothermal and solvothermal synthesis: simple approach with exceptional catalytic implications
Bohigues, Benjamin,Boronat, Mercedes,Corma, Avelino,Lopes, Christian W.,Meira, Débora M.,Moliner, Manuel,Rojas-Buzo, Sergio
, p. 10106 - 10115 (2021)
The Lewis/Br?nsted catalytic properties of the Metal-Organic Framework (MOF) nodes can be tuned by simply controlling the solvent employed in the synthetic procedure. In this work, we demonstrate that Hf-MOF-808 can be prepared from a material with a higher amount of Br?nsted acid sites,viamodulated hydrothermal synthesis, to a material with a higher proportion of unsaturated Hf Lewis acid sites,viamodulated solvothermal synthesis. The Lewis/Br?nsted acid properties of the resultant metallic clusters have been studied by different characterization techniques, including XAS, FTIR and NMR spectroscopies, combined with a DFT study. The different nature of the Hf-MOF-808 materials allows their application as selective catalysts in different target reactions requiring Lewis, Br?nsted or Lewis-Br?nsted acid pairs.
Phosphonate functionalized carbon spheres as Br?nsted acid catalysts for the valorization of bio-renewable a-pinene oxide totrans-carveol
Advani, Jacky H.,Biradar, Ankush V.,Singh, Amravati S.
, p. 7210 - 7217 (2020)
Herein, we report a simple route for the synthesis of phosphonate functionalized Br?nsted solid acid carbon spheres as heterogeneous catalyst for the valorization of bio-derived a-pinene oxide. The Br?nsted acidity was generatedviatwo steps; hydrothermal carbonization of sugar to produce carbon microspheres followed by PCl3treatment to form phosphonate functionalized carbon. The presence of phosphonate was confirmed by CP-MAS31P and13C NMR. In addition, the presence of the P-C, O-P-C and HO-P?O bonds of the phosphonate group was confirmed by FT-IR,31P NMR, and XPS. SEM-EDAX analysis revealed the presence of a phosphorus content of ~1.71 wt% on the surface of the catalyst while elemental mapping showed a uniform dispersion of phosphorus over the carbon spheres. The as-synthesized Br?nsted solid acid catalyst was used for the isomerization of a-pinene oxide which gave 100% conversion with 67%trans-carveol selectivity in highly polar basic solvent in 1 h reaction time. Also, the catalyst showed good recyclable activity even after five cycles.
Heteropoly acid catalysts in upgrading of biorenewables: Synthesis of para-menthenic fragrance compounds from α-pinene oxide
Ribeiro, Cláudio J.A.,Pereira, Matheus M.,Kozhevnikova, Elena F.,Kozhevnikov, Ivan V.,Gusevskaya, Elena V.,da Silva Rocha, Kelly A.
, p. 166 - 170 (2020)
The isomerization of α-pinene oxide in the presence of Cs2.5H0.5PW12O40 (CsPW) heteropolysalt as solid acid catalyst is reported. The reactions were performed in various solvents, which allowed to obtain trans-carveol, trans-sobrerol and pinol in 60–80% yield each, which exceed the yields reported so far. The CsPW catalyst could be recovered and reused without loss of its activity and selectivity.
Pauson-Khand Reactions with Concomitant C?O Bond Cleavage for the Preparation of 5,5- 5,6- and 5,7-Bicyclic Ring Systems
Ma, Ding,Hu, Naifeng,Ao, Junli,Zang, Shaoli,Yu, Guo,Liang, Guangxin
supporting information, p. 1887 - 1891 (2021/02/26)
Pauson-Khand reactions (PKR) with concomitant C?O bond cleavage have been developed for construction of 5,5- 5,6- and 5,7-bicyclic ring systems bearing complex stereochemistry. The chemistry generates intermolecular PKR-type products in an absolute regio- and stereochemical control which is hardly achievable through real intermolecular Pauson-Khand reactions. A mechanism for this Pauson-Khand reaction has been proposed based on deuterium labelling experiments. (Figure presented.).
Photocontrolled Cobalt Catalysis for Selective Hydroboration of α,β-Unsaturated Ketones
Beltran, Frédéric,Bergamaschi, Enrico,Funes-Ardoiz, Ignacio,Teskey, Christopher J.
supporting information, p. 21176 - 21182 (2020/09/17)
Selectivity between 1,2 and 1,4 addition of a nucleophile to an α,β-unsaturated carbonyl compound has classically been modified by the addition of stoichiometric additives to the substrate or reagent to increase their “hard” or “soft” character. Here, we demonstrate a conceptually distinct approach that instead relies on controlling the coordination sphere of a catalyst with visible light. In this way, we bias the reaction down two divergent pathways, giving contrasting products in the catalytic hydroboration of α,β-unsaturated ketones. This includes direct access to previously elusive cyclic enolborates, via 1,4-selective hydroboration, providing a straightforward and stereoselective route to rare syn-aldol products in one-pot. DFT calculations and mechanistic experiments confirm two different mechanisms are operative, underpinning this unusual photocontrolled selectivity switch.
Chiral Imidazo[1,5- a]pyridine-Oxazolines: A Versatile Family of NHC Ligands for the Highly Enantioselective Hydrosilylation of Ketones
Chinna Ayya Swamy,Varenikov, Andrii,Ruiter, Graham De
supporting information, p. 247 - 257 (2020/02/04)
Herein we report the synthesis and application of a versatile class of N-heterocyclic carbene ligands based on an imidazo[1,5-a]pyridine-3-ylidine backbone that is fused to a chiral oxazoline auxiliary. The key step in the synthesis of these ligands involves the installation of the oxazoline functionality via a microwave-assisted condensation of a cyano-azolium salt with a wide variety of 2-amino alcohols. The resulting chiral bidentate NHC-oxazoline ligands form stable complexes with rhodium(I) that are efficient catalysts for the enantioselective hydrosilylation of structurally diverse ketones. The corresponding secondary alcohols are isolated in good yields (typically >90%) with good to excellent enantioselectivities (80-93% ee). The reported hydrosilylation occurs at ambient temperatures (40 °C), with excellent functional group tolerability. Even ketones bearing heterocyclic substituents (e.g., pyridine or thiophene) or complex organic architectures are hydrosilylated efficiently, which is discussed further in this report.
Chemoselective Luche-Type Reduction of α,β-Unsaturated Ketones by Magnesium Catalysis
Jang, Yoon Kyung,Magre, Marc,Rueping, Magnus
, p. 8349 - 8352 (2019/10/16)
The chemoselective reduction of α,β-unsaturated ketones by use of an economic and readily available Mg catalyst has been developed. Excellent yields for a wide range of ketones have been achieved under mild reaction conditions, short times, and low catalyst loadings (0.2-0.5 mol %).
