Asymmetric organocatalysis of the addition of acetone to 2-nitrostyrene using N-diphenylphosphinyl-1,2-diphenylethane-1,2-diamine (PODPEN)

The highly enantioselective addition of acetone to 2-nitrostyrene, using N–diphenylphosphinyl-trans-1,2-diphenylethane-1,2-diamine (PODPEN) as catalyst, is described

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

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

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

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

N-Heterocyclic Carbene (NHC) Catalyzed Cycloaddition of CO 2 to N-Tosyl Aziridines: Regio and Stereoselective Synthesis of Oxazolidin-2-ones

10.1002/cctc.201200080ChemCatChem46774-77

Asymmetric organocatalysis

The field of asymmetric organocatalysis is rapidly developing and attracts an increasing number of research groups around the world. Here we present a brief overview of this area, guided by a mechanistic classification. Accordingly, organocatalysts are categorized as either Lewis base, Lewis acid, Brønsted base, or Brønsted acid catalysts