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A variety of N-substituted 3-aminocyclohex-2-enones were converted into the corresponding N-arylated α-iodo enaminones in high yields via concurrent α-iodination and N-arylation mediated by ArI(OAc)2. A mechanism is postulated to account for the reaction differences between the cyclic and the acyclic β-enamin�ones, which undergo predominant α-acetoxylation under the same reaction conditions. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs), with their regularly organized structures and solvent resistance, offer distinct advantages for constructing liquid-phase separation membranes. In nearly a decade of development, research has mainly focused on two-dimensional (2D) COFs, which yet give insufficient molecular selectivity due to inherent large pores. Here, we present a mixed-dimensional strategy of growing three-dimensional (3D) COFs on 2D COFs to build bilayered membranes for efficient organic solvent nanofiltration (OSN). The pores of 3D COFs interlace with those of 2D counterparts, resulting in a subnanoporous composite. We develop this 3D-/2D-COFs composite as robust membranes with a nanoscale thickness. The optimal bilayered membrane yields ethanol permeance of 12.2 L m−2 h−1 bar−1 with a molecular weight cutoff as low as ∼400 g mol−1, surpassing conventional COF-based OSN membranes. Importantly, the designed 3D-/2D-COFs membrane exhibits stable separation performance and excellent sieving ability to discriminate molecular mixtures. This exceptional molecular selectivity ultimately allows the separation of bioactive pharmaceuticals from impurities through our membrane. Overall, this work provides a design strategy for producing mixed-dimensional COF membranes to advance molecular separation in liquids. [Display omitted] • Mixed-dimensional covalent organic framework composites show reduced pore sizes. • Robust membranes of mixed-dimensional covalent organic frameworks are developed. • The optimal membrane exhibits high molecular selectivity with substantial permeances. • Our membrane performs high-selectivity purification of pharmaceuticals from impurities. [ABSTRACT FROM AUTHOR]

Permanently microporous materials have evolved as focal point of research for tackling issues in separation science and membrane technology. Covalent organic frameworks (COFs) stand out for their distinctive synergy of crystalline nature, uniform channels, and structural diversities. Three-dimensional (3D) COFs, distinguished by angstrom-sized and interconnected channels, hold special promise for separating small targets; however, this potential remains underexplored. Here, we report feasible growth of cationic 3D COF membranes on a flexible polymer substrate for versatile nanofiltration toward both molecules and ions. Through comprehensive performance evaluations, we reveal that the resultant membrane exhibits durable and prominent molecular selectivity to separate fine species with molecular weights above 300 g mol−1 at fast methanol permeation. Lanthanide ions of industrial value also can be harvested by the membrane with rejection rates of up to 91.4%. Together with its nonselectivity to competing ions, our membrane implements efficient extraction of rare earth elements from ion mixtures. These findings illuminate the potential of 3D COFs for liquid separation and offer a solution to building versatile membranes. [Display omitted] • A cationic three-dimensional covalent organic framework membrane is prepared. • The membrane shows exceptional molecular selectivity with high methanol permeance. • Efficient sieving of small molecules is achieved by the membrane. • Our membrane performs selective separation of rare earth elements. [ABSTRACT FROM AUTHOR]

By using a directed evolution approach, we have identified aminoacyl-tRNA synthetase variants with significantly enhanced activity for the incorporation of unnatural amino acids into proteins in response to the amber nonsense codon in bacteria. We demonstrated that the optimization of anticodon recognition of tRNA by aminoacyl-tRNA synthetase led to improved incorporation efficiency that is unnatural amino acid-specific. The findings will facilitate the creation of an optimized system for the genetic incorporation of unnatural amino acids in bacteria.

A novel approach to the key A-ring α, β-unsaturated aldehyde 1, an important intermediate for the preparation of 1α,25-dihydroxyvitamin D(3), has been developed. The strategy started from the inexpensive starting material (R)-carvone with an ene reaction serving as the key step toward the potential synthesis of vitamin D(3) analogues bearing the modification at the C-2 position.

Background: Severe acute pancreatitis (SAP) features fatal pathogenetic conditions and high mortality rate. The study of SAP complicated with multiple organ injuries is of important significance. In this study, we explored the protective effect of baicalin on multiple organs of SAP rats and compared it with that of octreotide through light and electron microscopic observations of the pathological changes., Methods: The improved Aho method was used to prepare SAP rat models. These rats were then randomly divided into a sham-operated group (n=45), a model control group (n=45), baicalin-treated group (n=45) and octreotide-treated group (n=45). Based on the difference in time points after operation, these groups were subdivided into 3, 6 and 12 hour subgroups (n=15). At the corresponding time point after operation, the mortality rate of rats was recorded, and then the rats were humanely killed to take samples of multiple organs that were subsequently examined for pathological changes under light and electron microscopy., Results: At 12 hours after operation, the mortality rate of rats in the baicalin- and octreotide-treated groups was lower than that in the model control group (P<0.05). Compared to the model control group, the pathological changes and pathological scores in the baicalin- and octreotide-treated groups were mitigated and relieved to varying degrees. The pathological changes under electron microscopy were also improved., Conclusions: Both baicalin and octreotide show good protective effects on multiple organs of SAP rats. Baicalin as a new drug has good prospects in the treatment of SAP.

The activity of N-acetylglucosaminyl transferase III (GnT III) in 7721 human heptocarcinoma cell was inhibited by two non-specific Ser/Thr protein kinase inhibitors, quercetin and trifluoperazine, and two PKC specific inhibitors, D-sphingosine and staurosporine. The change of GnT III activity paralleled that of membranous PKC (m-PKC) when the cells were treated with PMA, but not with that of cytosolic PKC (c-PKC). Quercetin, D-sphingosine and staurosporine also blocked the PMA activation of GnT-III. The inhibitory effects on m-PKC and GnT III were generally proportional to the concentration of quercetin and staurosporine. When crude GnT preparations of human and rat kidney were treated with ALP to remove the phosphate groups, the GnT III activities were significantly decreased. These results suggest that GnT III may be regulated by m-PKC directly or indirectly via the phosphorylation/dephosphorylation of the Ser/Thr residue.