Electrosynthesis of Thiocyanated/Iodinated/Brominated Pyrazol‐5‐amines and Thiocyanated Enamines via C(sp²)−H Functionalization

Abstract

An electrochemical method for the C-(sp 2 )À H thiocyanation of pyrazol-5-amines and enamines were developed in an undivided cell. A variety of thiocyanated pyrazol-5-amine and enamine derivatives were accessed in 36-91% yields, employing thiocyanate salts as electrolyte and thiocyanating reagent. Moreover, this electrochemical protocol can be extended to the synthesis of various iodinated and brominated pyrazol-5-amine derivatives in 51-95% yields. This electrochemical protocol does not require a metal or external chemical oxidants and tolerates unprotected amino groups.

Electrocatalytic C–H/S–H Coupling of Amino Pyrazoles and Thiophenols: Synthesis of Amino Pyrazole Thioether Derivatives

“…Meanwhile, Suga and co-workers achieved the electrosynthesis of thienoacene derivatives via an intramolecular dehydrogenative C–S coupling mediated by n Bu 4 NBr (Scheme d) . Encouraged by these works and our interest in C–H functionalization via electrochemistry, we herein report an electrocatalytic C–H/S–H coupling reaction of amino pyrazoles and thiols at room temperature (Scheme e). Mediated by NH 4 I, various amino pyrazole thioether derivatives were synthesized in moderate to good yields.…”

Electrochemically Enable N-Sulfenylation/Phosphinylation of Sulfoximines via Oxidative Dehydrocoupling Reaction

“…Electrochemical synthesis represents an environmentally friendly approach by using electrons as reagents to replace traditional redox reagents. , The oxidative dehydrocoupling reaction to construct carbon–carbon bond and carbon-heteroatom bond is well established via electrochemistry. , But the construction of heteroatom–heteroatom bond is relatively less explored . Continuing our interest in dehydrocoupling reaction via electrochemistry, we herein report an electrochemical N–H/S–H coupling reaction of sulfoximines and thiophenols, delivering diverse N -sulfenylsulfoximines with moderate to good yields under traditional redox reagent-free conditions. Moreover, this electrochemical protocol also succeeded in the preparation of N -phosphinylated sulfoximines via N–H/P–H coupling (Scheme e).…”