A copper-catalyzed three-component reaction of dithioacetals with diazo ketones and ketimines.

A copper-catalyzed three-component reaction of dithioacetals with diazo-ketones and ketimines has been reported. This reaction proceeds via trapping of the highly active sulfur ylide species, which are generated from thioacetal and carbene intermediates, with isatin-derived ketimine, providing an efficient protocol for the synthesis of acyclic thioacetal derivatives and medium-sized sulfur-containing heterocycles in good to high yields under mild reaction conditions with a broad substrate scope.

Diastereoselective aldol-type interception of phenolic oxonium ylides for the direct assembly of 2,2-disubstituted dihydrobenzofurans.

A Rh2(OAc)4 catalyzed intermolecular aldol-type interception of phenolic oxonium ylides with isatins has been developed, which provides an effective access to 2,2-disubstituted dihydrobenzofuran derivatives containing 3-hydroxyoxindole in high yields and with high diastereoselectivities under mild reaction conditions. The antiproliferation activity of these synthesized dihydrobenzofuran and 3-hydroxyoxindole hybrid products has been tested via the CCK8 assay in different cancer cell lines; compounds 3s and 3t exhibit good anticancer potency against human colon cancer cells (HCT116 cells, 3s: IC50 = 15.99 µM; 3t: IC50 = 14.48 µM) compared to other tested compounds.

Failure analysis of a rapid quench boiler for ethylene cracker.

The corrosion and leakage issues of rapid quench boilers have become increasingly prominent in ethylene plants, significantly disrupting the regular functioning of equipment. In pursuit of a more efficacious corrosion protection strategy, a study was conducted on the heat exchange tubes experiencing corrosion leakage in the quenching boiler of a petrochemical company. By means of macroscopic observation, chemical composition analysis, mechanical property analysis, metallographic analysis, fracture surface morphology observation, and energy spectrum analysis, combined with on-site process parameters, a comprehensive analysis of the failure causes of the corroded leakage sites was conducted. It was concluded that the perforation of the heat exchange tubes was caused by high-temperature oxygen corrosion and oxidation induced by scale accumulation, and reasonable countermeasures were proposed. According to X-ray diffraction analysis (XRD), it was found that the scale mainly consisted of Fe2O3 and Fe3O4, and the scale formation time was relatively long. It is speculated that the accumulation of scale is caused by the rust from the upstream equipment pipelines of the boiler water being carried into the quenching boiler with the fluid flow and accumulating at this location. Regarding the heat exchange tubes, the primary causes of failure are high-temperature oxygen corrosion and oxidation. To verify whether the relevant reactions can occur spontaneously, the critical transition temperature of the reactions is calculated using the free entropy function method. The calculated critical temperature for the occurrence of high-temperature oxygen corrosion and oxidation in the heat exchange tubes under failure conditions is determined to be T ＜ 1058 K ~ 785 °C. Therefore, under the conditions of heat exchange tube failure, high-temperature oxygen corrosion and oxidation can occur spontaneously.

Nav1.7 Modulator Bearing a 3-Hydroxyindole Backbone Holds the Potential to Reverse Neuropathic Pain.

Chronic pain is a growing global health problem affecting at least 10% of the world's population. However, current chronic pain treatments are inadequate. Voltage-gated sodium channels (Navs) play a pivotal role in regulating neuronal excitability and pain signal transmission and thus are main targets for nonopioid painkiller development, especially those preferentially expressed in dorsal root ganglial (DRG) neurons, such as Nav1.6, Nav1.7, and Nav1.8. In this study, we screened in virtual hits from dihydrobenzofuran and 3-hydroxyoxindole hybrid molecules against Navs via a veratridine (VTD)-based calcium imaging method. The results showed that one of the molecules, 3g, could inhibit VTD-induced neuronal activity significantly. Voltage clamp recordings demonstrated that 3g inhibited the total Na+ currents of DRG neurons in a concentration-dependent manner. Biophysical analysis revealed that 3g slowed the activation, meanwhile enhancing the inactivation of the Navs. Additionally, 3g use-dependently blocked Na+ currents. By combining with selective Nav inhibitors and a heterozygous expression system, we demonstrated that 3g preferentially inhibited the TTX-S Na+ currents, specifically the Nav1.7 current, other than the TTX-R Na+ currents. Molecular docking experiments implicated that 3g binds to a known allosteric site at the voltage-sensing domain IV(VSDIV) of Nav1.7. Finally, intrathecal injection of 3g significantly relieved mechanical pain behavior in the spared nerve injury (SNI) rat model, suggesting that 3g is a promising candidate for treating chronic pain.