Shufang Zhao

Evaluation of the binding of perfluorinated compound to pepsin: Spectroscopic analysis and molecular docking.

In this paper, we investigated the binding mode of perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) to pepsin using spectroscopies and molecular docking methods. Fluorescence quenching study indicated that their different ability to bind with pepsin. Meanwhile, time-resolved fluorescence measurements established that PFOA and PFNA quenched the fluorescence intensity of pepsin through the mechanism of static quenching. The thermodynamic parameters showed that hydrophobic forces were the main interactions. Furthermore, UV-vis, FTIR, three-dimensional fluorescence and molecular docking result indicated that PFCs impact the conformation of pepsin and PFOA was more toxic than PFNA. The conformational transformation of PFOA/PFNA-pepsin was confirmed through the quantitative analysis of the CD spectra. The present studies offer the theory evidence to analyze environmental safety and biosecurity of PFCs on proteases.

Practical Synthesis of Chromeno[2,3‐b]indole Skeleton via an Aldehyde Group Insertion/Aromatization Strategy

The synthesis of chromeno[2,3-b]indole from simple starting materials remains a demanding process. Herein, 2-bromoindole undergoes nucleophilic attack from salicylaldehyde, followed by intramolecular insertion of an aldehyde group and aromatization to generate the desired chromeno[2,3-b]indoles. Moreover, various functional groups were tolerated and a gram-scale synthesis of the product could be achieved under the optimized condition.

Chloroacetate Promotes and Participates in the Oxidative Annulation of Pyridines/Isoquinoline by Using Oxygen as the Oxidant.

The aerobic oxidative annulation of chalcones, pyridines/isoquinoline and ethyl chloroacetate to indolizines was achieved by cascade reaction. Various functional groups on chalcones were tolerated. And different pyridines derivatives could also be suitable substrates. Ethyl chloroacetate is an essential component in participating of the oxidative annulation process. Overall, this protocol is very practical and efficient by using molecular oxygen as oxidant with high selectivity for the annulation product.

Elemental sulfur accelerated the reactivity of the 3-position of indole for the construction of chromeno[2,3-b]indoles

An intermolecular cross-cyclization between salicylaldehydes and indoles for the preparation of chromeno[2,3-b]indole derivatives was successfully developed by using elemental sulfur as the promoter and oxidant. Various chromeno[2,3-b]indoles can be prepared using indoles and salicylaldehydes bearing different functional groups. The preliminary mechanistic investigations demonstrated that elemental sulfur not only acted as an additional oxidant but also facilitated the reactivity of the 3-position of indole.