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Two methods are reported for the 1,2- and 1,1-arylboration of α-methyl vinyl arenes. In the case of 1,2-arylboration, the formation of a quaternary center occurred through a rare cross-coupling reaction of a tertiary organometallic complex. 1,1-Arylboration was enabled by catalyst optimization and occurred through a β-hydride elimination/reinsertion cascade. Enantioselective variants of both processes are presented as well as mechanistic investigations., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A method for the regioselective 1,2‐arylboration of 1,3‐butadiene, a feedstock chemical, is reported. The reactions result in the formation of products that can be easily elaborated to other structures. The mechanistic details of this process are also discussed. [ABSTRACT FROM AUTHOR]

Two methods are reported for the 1,2‐ and 1,1‐arylboration of α‐methyl vinyl arenes. In the case of 1,2‐arylboration, the formation of a quaternary center occurred through a rare cross‐coupling reaction of a tertiary organometallic complex. 1,1‐Arylboration was enabled by catalyst optimization and occurred through a β‐hydride elimination/reinsertion cascade. Enantioselective variants of both processes are presented as well as mechanistic investigations. Keep your options open: Methods were developed for both the 1,2‐ and 1,1‐arylboration of α‐alkyl alkenyl arenes, including enantioselective variants. The formation of quaternary centers by 1,2‐arylboration occurred through a rare cross‐coupling of a tertiary organometallic complex (see scheme). 1,1‐Arylboration was enabled by catalyst optimization and occurred through a β‐hydride elimination/reinsertion cascade. [ABSTRACT FROM AUTHOR]

Effects of H2O on the activity and deactivation of Pd catalysts used for the oxidation of unburned CH4 present in the exhaust gas of natural-gas vehicles (NGVs) are reviewed. CH4 oxidation in a catalytic converter is limited by low exhaust gas temperatures (500-550 °C) and low concentrations of CH4 (400-1500 ppmv) that must be reacted in the presence of large quantities of H2O (10-15%) and CO2 (15%), under transient exhaust gas flows, temperatures, and compositions. Although Pd catalysts have the highest known activity for CH4 oxidation, water-induced sintering and reaction inhibition by H2O deactivate these catalysts. Recent studies have shown the reversible inhibition by H2O adsorption causes a significant drop in catalyst activity at lower reaction temperatures (below 450 °C), but its effect decreases (water adsorption becomes more reversible) with increasing reaction temperature. Thus above 500 °C H2O inhibition is negligible, while Pd sintering and occlusion by support species become more important. H2O inhibition is postulated to occur by either formation of relatively stable Pd(OH)2 and/or partial blocking by OH groups of the O exchange between the support and Pd active sites thereby suppressing catalytic activity. Evidence from FTIR and isotopic labeling favors the latter route. Pd catalyst design, including incorporation of a second noble metal (Rh or Pt) and supports high O mobility (e.g., CeO2) are known to improve catalyst activity and stability. Kinetic studies of CH4 oxidation at conditions relevant to natural gas vehicles have quantified the thermodynamics and kinetics of competitive H2O adsorption and Pd(OH)2 formation, but none have addressed effects of H2O on O mobility. [ABSTRACT FROM AUTHOR]

A method for the diastereoselective carboboration of 1,2-disubstituted styrenes with aryl/vinyl bromides and (Bpin)2 is reported. High diastereoselectivities and yields are observed for the formation of either diastereomer of the product from a single alkene isomer. These reactions provide access to a diverse range of structures from simple starting materials. [ABSTRACT FROM AUTHOR]

Copper-catalyzed Suzuki-Miyaura-type cross-coupling and carboboration processes are reported. The cross-couplings function well with a variety of substituted aryl iodides and aryl boronic esters and allows for orthogonal reactivity compared to palladium-catalyzed processes. The carboboration method includes both alkynes and allenes and provides access to highly substituted and stereodefined vinyl boronic esters. The alkyne carboboration method is highlighted in the simple one-pot synthesis of Tamoxifen. [ABSTRACT FROM AUTHOR]

Abstract: The conversion of naphthalene, tetralin or decalin to ring-opened products over Mo2C/HY, Mg- or K-Mo2C/HY, and a commercial Pd/HY catalyst, is reported. Conversion of all reactants at 300°C and 3MPa was higher over the Pd/HY catalyst than the Mo2C/HY catalysts. Tetralin was the least reactive among the three model compounds over both Pd/HY and Mo2C/HY. With decalin as reactant, higher selectivity to C10 products was obtained over the Mo2C/HY catalysts compared to the Pd/HY. The addition of K or Mg to Mo2C/HY improved the Mo2C dispersion while K also moderated the catalyst Bronsted acidity. The conversion of all three reactants was reduced by the addition of Mg or K to the Mo2C/HY, as was the carbon deposition. For all the studied catalysts, carbon deposition was lowest after reaction with decalin compared to naphthalene or tetralin. These results suggest that the deposited carbon has as its precursor, species that are derived from naphthalene or tetralin, rather than decalin, and the coke species are generated through bimolecular reactions on acid sites. Consequently, the catalysts with higher hydrogenation activity (Pd/HY and 1% K–7% Mo2C/HY) had lower deactivation rates. [Copyright &y& Elsevier]

Abstract: The complete recovery of the H2 stored on dodecahydro-N-ethylcarbazole was achieved at 443K and 101kPa using Pd/SiO2 catalysts, prepared by incipient wetness impregnation with calcination in He rather than air. The dehydrogenation turn-over frequency (TOF) and selectivity to the completely dehydrogenated product, N-ethylcarbazole, were dependent upon Pd particle size, with a maximum in both occurring with a 4wt.% Pd/SiO2 catalyst that had an average Pd particle size of 9nm. Over this catalyst, the dehydrogenation reaction proceeded to complete conversion within 22min and complete H2 recovery (5.8wt.%) within 1.6h at 443K and 101kPa. The structure sensitivity of the reaction and the observed product distribution are discussed in view of DFT calculations that showed that the adsorption of dodecahydro-N-ethylcarbazole on Pd required multiple catalytic sites and the heat of adsorption was dependent upon the surface structure. [Copyright &y& Elsevier]