Cu-Catalyzed [2+2+1] Cascade Annulation of Vinyl Iodonium Salts with Element Sulfur/Selenium for the Modular Synthesis of Thiophenes and Selenophenes

A [2+2+1] annulation protocol has been established for the modular synthesis of 2,4-disubstituted thiophenes/selenophens, with excellent regioselectivity. The reactions are catalyzed by copper salt with elemental sulfur and selenium serving...

Organocatalytic Silicon-Free SuFEx reactions for modular synthesis of sulfonate esters and sulfonamides

Sulfur(VI) fluoride exchange (SuFEx) click chemistry provides a powerful tool for rapid construction of modular connections. Here, we report a novel catalytic silicon-free SuFEx reaction with sulfonyl fluorides. Under the catalysis of 10 mol% N-heterocyclic carbene (NHC), a range of phenols and alcohols react with different sulfonyl fluorides to afford sulfonate esters in 49-99% yields. In addition, Under the relay catalysis of 10 mol% N-heterocyclic carbene and 10 mol% 1-hydroxybenzotriazole (HOBt), a variety of primary and secondary amines react with different sulfonyl fluorides to produce sulfonamides in 58%-99% yields. More than 140 sulfonylated products, including 17 natural product derivatives have been prepared through this method. Mechanism study showed that NHCs might act as a carbon-centered Brønsted base to catalyse the SuFEx click reactions via the formation of hydrogen bonding with phenols or alcohols.

Synthesis of -Tosyloxylated gem-Difluoroalkanes via Oxidative Fluorination of Vinyl Sulfonates Featuring A [2,3]-Sulfonyloxy Migration

The gem-difluoroalkanes widely exist in pharmaceuticals, agrochemicals and materials. Reported herein is a facile synthesis of tosyloxylated gem-difluoroalkanes via an oxidative fluorination of readily available vinyl sulfonates. An intriguing [2,3]-sulfonyloxy migration is involved as a key step. The OTs group in the product enables a divergent and modular synthesis of a wide variety of functionalized gem-difluoroalkanes via reliable SN2 reactions. Notable features of this protocol include mild reaction conditions, high efficiency and remarkably good functional-group tolerance.