Asymmetric, catalytic reactions of oxocarbenium ions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbenium ion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest en...

Introduction Bulk gold is a chemically inert metal, and had previously been disregarded as a candidate for catalytic applications [1]. Haruta’s pioneering work [2] showed exceptional reactivity on gold nanoparticles of 2-5 nm in diameter. Among reactions, the low temperature CO oxidation [3] on Au has created a strong interest. Model catalyst samples, which consist of planar metal oxide surface...

in this work, zno/sio2 nanoparticles were prepared using sol-gel method, and platinum particles were loaded on zno/sio2 nanoparticles by photoreductive method. samples were characterized by x-ray diffraction (xrd), scanning electron microscopy (sem) and fourier transform infrared spectroscopy (ft-ir). the xrd patterns showed that the zinc oxide samples have a wurtzite structure (hexagonal phase...

An O-Si bond construction protocol employing abundantly available and inexpensive NaOH as the catalyst is described. The method enables the cross-dehydrogenative coupling of an alcohol and hydrosilane to directly generate the corresponding silyl ether under mild conditions and without the production of stoichiometric salt byproducts. The scope of both coupling partners is excellent, positioning...

An anti-Markovnikov selective hydroamination of alkynes with N-silylamines to afford N-silylenamines is reported. The reaction is catalyzed by a bis(amidate)bis(amido)Ti(IV) catalyst and is compatible with a variety of terminal and internal alkynes. Stoichiometric mechanistic studies were also performed. This method easily affords interesting N-silylenamine synthons in good to excellent yields ...

Development of efficient catalysts for the direct hydrogenation CO2 to methanol is essential valorization this abundant feedstock. Here we show that a silica-supported Cu/Mo2CTx (MXene) catalyst achieves higher intrinsic formation rate per mass Cu than reference Cu/SiO2 with similar loading. The interface can be engineered due affinity partially reduced MXene surface (in preference SiO2 surface...

Tungstophosphoric acid (H3PW12O40) supported on silica-coated magnetite nanoparticles has been prepared and used as a heterogeneous catalyst (Fe3O4@SiO2@HPW) in the condensation of benzaldehyde (B) with glycerol (Gly) for production cyclic acetals. Physicochemical techniques, including scanning electron microscopy (SEM), transmission (TEM), Fourier-transform infrared spectrometry (FTIR), X-ray ...

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this owing to their CO bond activation capability thermal stability. Pd/SiO2 were investigated using carbon as a model reaction. The catalyst becomes active, the conversion increas...