Synthesis of 4-chalcogenyl pyrazoles via electrophilic chalcogenation/cyclization of α,ß-alkynic hydrazones.

A facile method for the synthesis of 4-chalcogenylated pyrazoles has been developed via electrophilic chalcogenation/cyclization of α,ß-alkynic hydrazones. The cyclization of α,ß-alkynic aldehyde hydrazones could be induced by using either sulfenyl chloride or the S-electrophiles generated in situ from the reaction of NCS and arythiol. The developed method was successfully applied to the synthesis of the sulfenyl analogue of celecoxib.

Steric and stereoscopic disulfide construction for cross-linkage via N-dithiophthalimides.

Disulfide bonds are a significant motif in life and drug-delivery systems. In particular, steric hindrance and stereoscopic disulfide linkers are closely associated with the stability of antibody-drug conjugates, which affects the potency, selectivity, and pharmacokinetics of drugs. However, limited availability and diversity of tertiary thiols impede the construction of steric and stereoscopic disulfides for cross-linkage in biochemistry and pharmaceuticals. Through modulating the mask effect of disulfurating reagents, we develop a facile and robust strategy for construction of diverse steric and stereoscopic disulfides via N-dithiophthalimides. The practical cross-linkage of biomolecules including amino acids, saccharides, and nucleosides with different drugs and fluorescent molecules is successfully established through hindered disulfide linkers.

N-Alkynylthio Phthalimide: A Shelf-Stable Alkynylthio Transfer Reagent for the Synthesis of Alkynyl Thioethers.

A new kind of electrophilic alkynylthiolating reagent, called N-alkynylthio phthalimide, is designed and synthesized herein. This electrophilic sulfenylating reagent can be easily prepared in three steps from commercially available phthalimide and corresponding silver acetylide. Furthermore, the N-alkynylthio phthalimides are demonstrated to be efficient alkynylthio transfer reagents that can react with various C-nucleophiles, including ß-ketoesters, aryl boronic acids, and Grignard reagents to afford a diverse range of alkynyl thioethers under mild conditions.

Copper(II)-Catalyzed Four-Component Oxysulfonylation/Diazenylation: Synthesis of α-Arylhydrazo-ß-keto Sulfones.

A new and convenient method for one-pot synthesis of α-arylhydrazo-ß-keto sulfones is developed via Cu (II)-catalyzed oxysulfonylation/diazenylation of alkenes. This four-component cascade reaction enables a series of α-arylhydrazo-ß-keto sulfone derivatives accessed from readily available alkenes, sulfinates, and diazonium salts under aerobic conditions. Furthermore, the 3-sulfonyl cinnolin-4(1 H)-one skeleton is successfully constructed from the corresponding α-arylhydrazo-ß-keto sulfone product under basic conditions.