Two-component metal-free catalytic oxidative sulfenylation of pyrazolones with thiols has been achieved using the biomimetic flavin and iodine. The methodology is mild and eco-friendly, proceeds in the presence of air or molecular oxygen (1 atm) as the sole sacrificial reagent, and generates water as the only byproduct. The methodology was also extended to the sulfenylation of pyrazoles and electron-rich benzenes and afforded a series of thioethers in good yields.

The aerobic oxidative cross-coupling of indoles with azoles driven by flavin-iodine-coupled organocatalysis has been developed for the green synthesis of 2-(azol-1-yl)indoles. The coupled organocatalytic system enabled the one-pot threecomponent synthesis of 2-azolyl-3-thioindoles from indoles, azoles, and thiols in an atom-economical manner by utilizing molecular oxygen as the only sacrificial reagent.

Herein, we report an aerobic oxidative C−N bond-forming process that enables the facile synthesis of imidazo[1,2a]pyridines and takes advantage of a coupled organocatalytic system that uses flavin and iodine. Furthermore, the dual catalytic system can be applied to the one-pot, three-step synthesis of 3-thioimidazo[1,2-a]pyridines from aminopyridines, ketones, and thiols.

We report the first experiments, where simultaneous electrical resistivity and elastic wave velocity measurements are acquired during the triaxial deformation of granite under brine-saturated conditions. Both the resistivity and elastic wave velocity increase slightly during the early stage of deformation owing to crack closure, and then decrease systematically owing to crack development as the sample approaches failure. We observe a complex relationship among the resistivity, elastic wave velocity, and porosity during deformation that is likely attributed to their different sensitivities to crack orientation, tortuosity, and connectivity. The electrical resistivity changes tend to decline as the sample approaches failure owing to the nearly complete crack connectivity, whereas the elastic wave velocities continue to decrease. These characteristic changes in resistivity and velocity at the discrete stages of deformation may provide a clue to understanding structural changes in crystalline basements that are related to crack development and fluid infiltration. Graphical Abstract