Resolution of (D,L)-Phenylalanine in Biphasic System by α-Chymotrypsin Immobilized on Superparamagnetic Nanogels

α-Chymotrypsin immobilized on super paramagnetic nanogels covered with carboxyl groups, exhibited high stereoselectivity in kinetic resolution of racemic phenylalanine in toluene/water biphasic system, and even improved reusability over its parent free enzyme. The results also showed that the addition of ionic liquid to water phase could enhance the stereoselectivity of the immobilized enzyme to a certain extent while the conversion yield decreased. The long-term stability allows the supported enzyme with nano-scaled dimension to use in continuous chiral resolution reaction, which opens a new horizon for enzymatic chiral resolution in large-scale production.     

Merging Gradient-Based Methods to Improve Benchtop NMR Spectroscopy: A New Tool for Flow Reaction Optimization

Emerging low cost, compact NMR spectrometers that can be connected in-line to a flow reactor are suited to study reaction mixtures. The main limitation of such spectrometers arises from their lower magnetic field inducing a reduced sensitivity and a weaker spectral resolution. For enhancing the spectral resolution, the merging of Pure-Shift methods recognized for line narrowing with solvent elimination schemes was implemented in the context of mixtures containing protonated solvents. One more step was achieved to further enhance the resolution power on compact systems, thanks to multiple elimination schemes prior to Pure-Shift pulse sequence elements. For the first time, we were able to remove up to 6 protonated solvent signals simultaneously by dividing their intensity by 500 to 1700 with a concomitant spectral resolution enhancement for signals of interest from 9 to 12 as compared to the standard 1D ¹H. Then, the potential of this new approach was shown on the flow synthesis of a complex benzoxanthenone structure.     

Asymmetric one-pot synthesis of five- and six-membered lactones via dynamic covalent kinetic resolution: Exploring the regio- and stereoselectivities of lipase

Cascade lipase-catalyzed lactonization has been applied to dynamic hemithioacetal formation, leading to efficient five- and six-membered lactone synthesis as well as chiral discrimination. Solvent-dependent regioselectivity was observed for the selective formation of 1,3-oxathiolan-5-one and γ-butyrolactone derivatives.     

Micro‐Lensed Fiber Laser Desorption Mass Spectrometry Imaging Reveals Subcellular Distribution of Drugs within Single Cells

The visualization of temporal and spatial changes in the intracellular environment has great significance for chemistry and bioscience research. Mass spectrometry imaging (MSI) plays an important role because of its unique advantages, such as being label‐free and high throughput, yet it is a challenge for laser‐based techniques due to limited lateral resolution. Here, we develop a simple, reliable, and economic nanoscale MSI approach by introducing desorption laser with a micro‐lensed fiber. Using this integrated platform, we achieved 300 nm resolution MSI and successfully visualized the distribution of various small‐molecule drugs in subcellular locations. Exhaustive dynamic processes of anticancer drugs, including releasing from nanoparticle carriers entering nucleus of cells, can be readily acquired on an organelle scale. Considering the simplicity and universality of this nanoscale desorption device, it could be easily adapted to most of laser‐based mass spectrometry applications.     

Efficient Synthesis of Differentiated syn‐1,2‐Diol Derivatives by Asymmetric Transfer Hydrogenation–Dynamic Kinetic Resolution of α‐Alkoxy‐Substituted β‐Ketoesters

Asymmetric transfer hydrogenation was applied to a wide range of racemic aryl α‐alkoxy‐β‐ketoesters in the presence of well‐defined, commercially available, chiral catalyst Ru^II–(N‐p‐toluenesulfonyl‐1,2‐diphenylethylenediamine) and a 5:2 mixture of formic acid and triethylamine as the hydrogen source. Under these conditions, dynamic kinetic resolution was efficiently promoted to provide the corresponding syn α‐alkoxy‐β‐hydroxyesters derived from substituted aromatic and heteroaromatic aldehydes with a high level of diastereoselectivity (diastereomeric ratio (d.r.)>99:1) and an almost perfect enantioselectivity (enantiomeric excess (ee)>99 %). Additionally, after extensive screening of the reaction conditions, the use of Ru^II‐ and Rh^III‐tethered precatalysts extended this process to more‐challenging substrates that bore alkenyl‐, alkynyl‐, and alkyl substituents to provide the corresponding syn α‐alkoxy‐β‐hydroxyesters with excellent enantiocontrol (up to 99 % ee) and good to perfect diastereocontrol (d.r.>99:1). Lastly, the synthetic utility of the present protocol was demonstrated by application to the asymmetric synthesis of chiral ester ethyl (2S)‐2‐ethoxy‐3‐(4‐hydroxyphenyl)‐propanoate, which is an important pharmacophore in a number of peroxisome proliferator‐activated receptor α/γ dual agonist advanced drug candidates used for the treatment of type‐II diabetes.     

Flashlamp Pumped Emulsion Dye Laser

Results of experimental study of flashlamp pumped cc-NPO emulsion dye laser are reported. Superior quality α-NPO emulsion over α-NPO solution in n-hexane is found.     

Fitting-free curve resolution of spectroscopic data: Chemometric and physical chemical viewpoints

In this paper the authors have investigated spectroscopic data analysis according to a recent development, i.e. the Direct Inversion in the Spectral Subspace (DISS) procedure.