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1.
Ruthenium‐Catalyzed Reductive Methylation of Imines Using Carbon Dioxide and Molecular Hydrogen 下载免费PDF全文
Dr. Kassem Beydoun Ghazi Ghattas Katharina Thenert Prof. Dr. Jürgen Klankermayer Prof. Dr. Walter Leitner 《Angewandte Chemie (International ed. in English)》2014,53(41):11010-11014
The use of the well‐defined [Ru(triphos)(tmm)] catalyst, CO2 as C1 source, and H2 as reducing agent enabled the reductive methylation of isolated imines, as well as the direct coupling of amines with aldehydes and the subsequent reductive methylation of the in situ formed imines. The method, which afforded the corresponding N‐methyl amines in very good to excellent yields, was also used for the preparation of the antifungal agent butenafine in one step with no apparent waste, thus increasing the atom efficiency of its synthesis. 相似文献
2.
The direct coupling of aryl halides with thiophene would be a considerable advantage for sustainable development because of only HBr associated with a base as by-product is formed and the number of steps to prepare these compounds is less than in more classical coupling reactions. We observed that through the use of only 0.2 mol% Pd(OAc)2 as the catalyst, a range of aryl bromides undergoes coupling via a C-H bond activation/functionalization reaction with thiophene to give 2-arylated thiophenes in good yields. In most cases, only traces of polyarylated thiophenes were detected when a large excess of thiophene was employed. This air-stable catalyst can be used with a wide variety of aryl bromides. 相似文献
3.
Chiraz Youssef Hamed Ben Ammar Mohamed Belhouchet Kassem Beydoun Ridha Ben Salem Henri Doucet Pierre H. Dixneuf 《Journal of heterocyclic chemistry》2011,48(5):1126-1131
2‐(Arylidene)cyanomethylbenzoxazoles have been prepared in water from benzoxazole‐2‐ylacetonitriles. Using multi‐component reactions, a variety of heterocycles containing benzoxazole and nitrile functionality has been prepared. J. Heterocyclic Chem., (2011). 相似文献
4.
Beydoun K Zaarour M Williams JA Doucet H Guerchais V 《Chemical communications (Cambridge, England)》2012,48(9):1260-1262
Palladium-catalysed direct 5-arylation of metallated thiophenes of fac-Ir(N^C(3')-thpy)(3) with aryl bromides via C-H bond functionalisation allows the synthesis of a variety of new Ir complexes in only one step (thpyH = 2,2'-thienylpyridine). The method offers simple modification of the nature of the ligand and hence of the photophysical properties of such complexes. 相似文献
5.
Ruthenium‐Catalyzed Synthesis of Dialkoxymethane Ethers Utilizing Carbon Dioxide and Molecular Hydrogen 下载免费PDF全文
Katharina Thenert Dr. Kassem Beydoun Jan Wiesenthal Prof. Dr. Walter Leitner Prof. Dr. Jürgen Klankermayer 《Angewandte Chemie (International ed. in English)》2016,55(40):12266-12269
The synthesis of dimethoxymethane (DMM) by a multistep reaction of methanol with carbon dioxide and molecular hydrogen is reported. Using the molecular catalyst [Ru(triphos)(tmm)] in combination with the Lewis acid Al(OTf)3 resulted in a versatile catalytic system for the synthesis of various dialkoxymethane ethers. This new catalytic reaction provides the first synthetic example for the selective conversion of carbon dioxide and hydrogen into a formaldehyde oxidation level, thus opening access to new molecular structures using this important C1 source. 相似文献
6.
Preparation of nanosized crystalline TiO2 particles at low temperature for photocatalysis 总被引:1,自引:0,他引:1
Nanocrystalline titanium dioxide (TiO2) particles were prepared by a modified alkoxide method under acidic conditions at temperatures ranging from 60°C to 90°C. The reaction temperature was used to control the crystalline phase of the TiO2 particles. At 60°C and 75°C rutile was formed whilst at 90°C anatase and brookite were formed.The photocatalytic activity of the prepared particles was tested for the degradation of sucrose. The photocatalytic activities of the prepared nanosized TiO2 were compared to those obtained from Degussa P-25 TiO2 as well as TiO2 crystalline samples prepared using the conventional sol–gel/heat treatment method. At low organic concentrations, Degussa P-25 exhibited higher photocatalytic behaviour than all the prepared particles while, at high organic concentrations, the nanosized TiO2 particles prepared at low temperature displayed an activity comparable to Degussa P-25 but much higher than the heat treated sample. The formation of excess intermediates during the degradation of higher sucrose loadings is believed to hinder the photoactivity of Degussa P-25, while the prepared TiO2 particles are able to maintain their activity for the degradation of the intermediates of sucrose. 相似文献
7.
S.?Watson J.?Scott D.?Beydoun R.?AmalEmail author 《Journal of nanoparticle research》2005,7(6):691-705
A crystalline titanium dioxide coating was deposited onto silica insulated magnetite particles to prepare a stable magnetic
photocatalyst. The direct deposition of crystalline titanium dioxide was conducted by aging dispersions of insulated magnetite
particles in a titanium sol–gel precursor mixture at 60–90°C. The coating process was found to be influenced by pH, alkoxide
precursor concentration, aging time and reaction temperature. A mechanism for the formation of the titanium dioxide coating
has been proposed. The photocatalytic performance of the prepared particles was found to be related to the preparation conditions. 相似文献
8.
Occurrence and prevention of photodissolution at the phase junction of magnetite and titanium dioxide 总被引:12,自引:0,他引:12
Donia Beydoun Rose Amal Gary Low Stephen McEvoy 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):193-200
A stable magnetic photocatalyst was prepared by coating a magnetic core with a layer of photoactive titanium dioxide. A direct deposition of titanium dioxide onto the surface of magnetic iron oxide particles proved ineffective in producing a stable magnetic photocatalyst, with high levels of photodissolution being observed with these samples. This observed photodissolution is believed to be due to the dissolution of the iron oxide phase, induced by the photoactive the titanium dioxide layer due to electronic interactions at the phase junction in these magnetic photocatalysts. The introduction of an intermediate passive SiO2 layer between the titanium dioxide phase and the iron oxide phase inhibited the direct electrical contact and hence prevented the photodissolution of the iron oxide phase. The magnetic photocatalyst is for use in slurry-type reactors from which the catalyst can be easily recovered by the application of an external magnetic field. 相似文献
9.
10.
Dr. Kassem Beydoun Prof. Dr. Jürgen Klankermayer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(49):11412-11415
Herein a transition-metal catalyst system for the selective synthesis of cyclic and linear acetals from the combined utilization of carbon dioxide, molecular hydrogen, and biomass derived diols is presented. Detailed investigations on the substrate scope enabled the selectivity of the reaction to be largely guided and demonstrated the possibility of integrating a broad variety of substrate molecules. This approach allowed a change between the favored formation of cyclic acetals and linear acetals, originating from the bridging of two diols with a carbon-dioxide based methylene unit. This new synthesis option paves the way to novel fuels, solvents, or polymer building blocks, by the recently established “bio-hybrid” approach of integrating renewable energy, carbon dioxide, and biomass in a direct catalytic transformation. 相似文献