Enantioselective C2-Alkylation of Indoles through a Redox-Relay Heck Reaction of 2-Indole Triflates

A palladium-catalyzed enantioselective redox-relay Heck reaction of 2-indole triflates and disubstituted alkenes is reported. This process combines readily available indole triflates with a variety of alkenes to afford a range of indole derivatives bearing a stereocenter adjacent to C2. Enantioselectivity is achieved through use of a simple pyridine-oxazoline ligand. Tuning the electronics of the indole, through judicious choice of N-protecting group, is required to ensure selective β-hydride elimination away from the indole core. Utility of this method is highlighted in a modular formal synthesis of an S1P₁ agonist precursor developed by Merck.     

[Ru(dcbpy)2dppz]2+/Fullerene Cosensitized PTB7-Th for Ultrasensitive Photoelectrochemical MicroRNA Assay

A new cosensitization photoelectrochemical (PEC) strategy was established by using a donor–acceptor-type photoactive material, poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7-Th), as a signal indicator, which was cosensitized with bis(4,4′dicarboxyl-2,2′-bipyridyl)(4,5,9,14-tetraazabenzo[b]triphenylene)ruthenium(II) ([Ru(dcbpy)₂dppz]²⁺) embedded in the grooves of the DNA duplex and fullerene (nano-C₆₀) immobilized on the surface of DNA nanoflowers for microRNA assay. [Ru(dcbpy)₂dppz]²⁺ and nano-C₆₀ could effectively enhance the photoelectric conversion efficiency (PCE) of PTB7-Th as a result of well-matched energy levels among nano-C₆₀, [Ru(dcbpy)₂dppz]²⁺ and PTB7-Th, leading to a clearly enhanced photocurrent signal. Meanwhile, a target recycling magnification technique based on duplex-specific nuclease was applied in this work to obtain higher detection sensitivity. The proposed biosensor demonstrated excellent analytical properties within a linear detection range of 2.5 fm to 2.5 nm and a limit of detection down to 0.83 fm . Impressively, this cosensitization PEC strategy offers an effective and convenient avenue to significantly improve the PCE of a photoactive material, resulting in a remarkably improved photocurrent signal for ultrasensitive and highly accurate detection of various targets.     

Directing-Group-Free C7-Alkylations of N-Alkylindoles Mediated by Cationic Zirconium Complexes: Role of Brønsted Acid for Catalytic Manifold

Highly position selective alkylations of N-alkylindoles at C7-positions have been enabled by cationic zirconium complexes. The strategy provides a straightforward access to install alkyl groups at C7-positions of indoles without a complex directing group. Mechanistic studies provided support for the importance of Brønsted acids in the catalytic manifold.     

Electrochemical Signal Enhancer Fabricated Using Lysine‐rich Peptide for Ultrasensitive Electrochemical DNA Biosensor Analysis

Here we present a novel design of electrochemical signal enhancer to increase the detection sensitivity of electrochemical DNA biosensors. The key element of this enhancer is a lysine‐rich peptide (LRP). Its C‐terminal is conjugated with a planer molecule, being able to intercalate into the base pairs of probe‐target duplexes. The lysine residues of LRP are covalently linked with electrochemical signal indicators, acting as an assembly of electrochemical signal indicators. Experimental results proved the feasibility of the novel design. We have examined the effects of the numbers of lysine residues and the hybridization conditions on the detection sensitivity. The optimization procedures have led to significant sensitivity enhancement, and the LOD (limit of detection) has been determined to be 1.4 amol. This enhancer demonstrates advantages of easy operation, simple instrumentation, and high exemption from environmental influence.     

Surface modification of hollow microsphere Li1.2Ni1/3Co1/3Mn1/3O2 cathode by coating with CoAl2O4

Journal of Solid State Electrochemistry - Li1.2Ni1/3Co1/3Mn1/3O2 was synthesized as a cathode material for lithium-ion batteries and coated with various amounts of CoAl2O4 (0–5 wt%)...     

Optimal harvesting strategy of a stochastic inshore–offshore hairtail fishery model driven by Lévy jumps in a polluted environment

Nonlinear Dynamics - With the increasing demand for aquatic products all over the world, exploring the interactions between inshore and offshore fisheries is one of the meaningful issues to help...     

12β-Acetyloxyperforatin,a New Limonoid from Harrisonia Perforata

A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme.