New class of chiral ligands derived from isosorbide: first application in asymmetric transfer hydrogenation

A new class of β-amino alcohol and diamine ligands was prepared from isosorbide as a chiral renewable resource. The original wedge-shaped structure of isosorbide offers an interesting chiral pocket to promote the metal-catalyzed enantioselective reduction of ketones by transfer hydrogenation.     

Synthesis of functionalized chiral ammonium,imidazolium, and pyridinium-based ionic liquids derived from (−)-ephedrine using solvent-free microwave activation. Applications for the asymmetric Michael addition

An efficient procedure for the synthesis of functionalized chiral ammonium, imidazolium, and pyridinium-based ionic liquids derived from (1R, 2S)-ephedrine using solvent-free microwave activation has been described. Good yields were obtained in very short reaction time. These chiral ionic liquids were used as chiral reaction media for the asymmetric Michael addition, giving good yields and moderate enantioselectivities.     

Effects of elicitors on the enhancement of asiaticoside biosynthesis in cell cultures of centella (Centella asiatica L. Urban)

In this work, the effects of elicitor concentration and elicitation day on the growth and asiaticoside production of centella cells were investigated. The results showed that 2-hydroxybenzoic acid from 50?C200 ??M and yeast extract from 2?C5 g L^?1 had different eliciting influences. The addition of 2-hydroxybenzoic acid and yeast extract to the cultures strongly enhanced asiaticoside production in centella cells. The increase in asiaticoside content induced by the addition of 100 ??M of 2-hydroxybenzoic acid and 4 g L^?1 of yeast extract at day 10 of inoculation was about 5- and 3.5-fold, respectively, as compared with that of the reference cells. In general, 2-hydroxybenzoic acid (abiotic elicitor) was more effective in enhancing asiaticoside biosynthesis than yeast extract (biotic elicitor).     

Highly Amino Acid Selective Hydrolysis of Myoglobin at Aspartate Residues as Promoted by Zirconium(IV)‐Substituted Polyoxometalates

SDS‐PAGE/Edman degradation and HPLC MS/MS showed that zirconium(IV)‐substituted Lindqvist‐, Keggin‐, and Wells–Dawson‐type polyoxometalates (POMs) selectively hydrolyze the protein myoglobin at Asp? X peptide bonds under mildly acidic and neutral conditions. This transformation is the first example of highly sequence selective protein hydrolysis by POMs, a novel class of protein‐hydrolyzing agents. The selectivity is directed by Asp residues located on the surface of the protein and is further assisted by electrostatic interactions between the negatively charged POMs and positively charged surface patches in the vicinity of the cleavage site.     

NMR spectroscopic data of some 1-alkoxy-2,2-di(carbonyl, carboxyl, cyano)-substituted ethylenes

The 1H-13C NMR shifts as well as 1H and 13C coupling constants of 14 alkoxymethylene malonic acid and acetoacetic acid derivatives and two alkoxymethylene acetylacetones are reported. The 17O NMR spectra have been recorded for six of them. The long-range coupling 3J(H-C=C-C(R)) has been used for determining the stereochemistry of the double bond.     

Enzyme Engineering for High-Yielding Amide Formation: Lipase-Catalyzed Synthesis of N-Acyl Glycines in Aqueous Media

Amide syntheses remain a key challenging green chemistry reaction. For instance, green synthesis of N-acyl glycines as biosurfactants and therapeutics is highly desirable to replace chemical pathways using toxic phosgene. Herein, we report a novel concept for enzymatic amidation in an aqueous system via glycerol activation of fatty acids and theirsubsequent aminolysis with glycine to synthesize N-acyl glycines. We then engineer an enzyme (proRML) by reshaping its catalytic pocket to enhance its aminolysis activity and catalytic efficiency by 103-fold and 465-fold, respectively. The evolved proRML (D156S/L258K/L267N/S83D/L58K/R86K/W88V) catalyzed the amidation of a fatty acid with glycine to give N-lauroylglycine with high yield (80 %). It accepts a broad range of medium- to long-chain fatty acids (C₈–C₁₈), giving high yields of N-decanoyl-, N-myristoyl-, and N-oleoylglycine. The developed amidation concept may be general, and the engineered enzyme is useful for the green synthesis of N-acyl glycines.     

Highly Efficient Electrochemical Nitrate and Nitrogen Reduction to Ammonia under Ambient Conditions on Electrodeposited Cu-Nanosphere Electrode

The electrochemical reduction reaction of nitrogenous species such as NO₃⁻ (NO₃RR) and N₂ (NRR) is a promising strategy for producing ammonia under ambient conditions. However, low activity and poor selectivity of both NO₃RR and NRR remain the biggest problem of all current electrocatalysts. In this work, we fabricated Cu-nanosphere film with a high surface area and dominant with a Cu(200) facet by simple electrodeposition method. The Cu-nanosphere film exhibits high electrocatalytic activity for NO₃RR and NRR to ammonia under ambient conditions. In the nitrate environment, the Cu-nanosphere electrode reduced NO₃⁻ to yield NH₃ at a rate of 5.2 mg/h cm², with a Faradaic efficiency of 85 % at −1.3 V. In the N₂-saturated environment, the Cu-nanosphere electrode reduced N₂ to yield NH₃ with the highest yield rate of 16.2 μg/h cm² at −0.5 V, and the highest NH₃ Faradaic efficiency of 41.6 % at −0.4 V. Furthermore, the Cu-nanosphere exhibits excellent stability with the NH₃ yield rate, and the Faradaic efficiency remains stable after 10 consecutive cycles. Such high levels of NH₃ yield, selectivity, and stability at low applied potential are among the best values currently reported in the literature.