266 research outputs found

    Highly active water-soluble palladium catalyst for the regioselective carbonylation of vinyl aromatics to 2-arylpropionic acids

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    This is the published version. Copyright © The Royal Society of Chemistry 2000A novel water-soluble Pd complex containing pyridine carboxylate and TPPTS as ligands is a highly active catalyst for the carbonylation of vinyl aromatics under biphasic conditions and provides high regioselectivity to 2-arylpropionic acids

    Highly active supported palladium catalyst for the regioselective synthesis of 2-arylpropionic acids by carbonylation

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    This is the published version. Copyright © Royal Society of Chemistry 1999A catalyst system consisting of supported palladium in the presence of phosphine ligands, TsOH and LiCl catalyses the carbonylation of 1-arylethanols to 2-arylpropionic acids with significantly improved activity and regioselectivity; the catalyst can be recycled with no loss in activity and selecivity

    Indole and azaindole halogenation catalyzed by the RebH enzyme variant 3-LSR utilizing co-purified E. coli reductase

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    Biocatalytic C-H halogenation is becoming increasingly attractive due to excellent catalyst-controlled selectivity and environmentally benign reaction conditions. Significant efforts have been made on enzymatic halogenation of industrial arenes in a cost-effective manner. Here we report an unprecedented enzymatic halogenation of a panel of industrially important indole, azaindole and anthranilamide derivatives using a thermostable RebH variant without addition of any external flavin reductase enzyme. The reactions were catalyzed by the RebH variant 3-LSR enzyme with the help of a co-purified E. coli reductase identified as alkyl hydroperoxide reductase F (AhpF)

    Growth of Large-Area and Highly Crystalline MoS2 Thin Layers on Insulating Substrates

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    The two-dimensional layer of molybdenum disulfide (MoS2) has recently attracted much interest due to its direct-gap property and potential applications in optoelectronics and energy harvesting. However, the synthetic approach to obtain high quality and large-area MoS2 atomic thin layers is still rare. Here we report that the high temperature annealing of a thermally decomposed ammonium thiomolybdate layer in the presence of sulfur can produce large-area MoS2 thin layers with superior electrical performance on insulating substrates. Spectroscopic and microscopic results reveal that the synthesized MoS2 sheets are highly crystalline. The electron mobility of the bottom-gate transistor devices made of the synthesized MoS2 layer is comparable with those of the micromechanically exfoliated thin sheets from MoS2 crystals. This synthetic approach is simple, scalable and applicable to other transition metal dichalcogenides. Meanwhile, the obtained MoS2 films are transferable to arbitrary substrates, providing great opportunities to make layered composites by stacking various atomically thin layers.Comment: manuscript submitted on 11-Dec-2011, revision submitted on 16-Feb-201

    Catalytic Asymmetric Pictet-Spengler Reaction

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    A catalytic asymmetric Pictet−Spengler reaction has been developed, wherein treating substituted tryptamines with an aldehyde in the presence of a catalytic amount of a chiral phosphoric acid provides the corresponding tetrahydro-β-carboline derivatives in high yields and enantiomeric excesses. The reaction works well with both aliphatic and aromatic aldehydes
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