Mechanochemical Vicinal Dibromination of Unactivated Alkenes and Alkynes Using Piezoelectric Material as a Redox Catalyst.

Mechanoredox chemistry is a rapidly evolving field at the intersection of mechanical forces and chemical reactions. Herein, we have reported a vicinal dibromination of unsaturated hydrocarbons using piezoelectric material (Li2TiO3) as a redox catalyst. Furthermore, the reaction can be efficiently scaled up to 10 mmol and performed under an air atmosphere at room temperature without solvents or external reductants, and Li2TiO3 can be reused multiple times without a structural change.

Copper-Catalyzed 1,4-Trifluoromethylthio-Arylsulfonylation of 1,3-Enynes via the Insertion of Sulfur Dioxide.

A copper-catalyzed trifluoromethylthio-arylsulfonylation between 1,3-enynes, AgSCF3, aryldiazonium tetrafluoroborates, and SO2 (from SOgen) is presented, which could introduce sulfone, SCF3, and allene moieties into one molecule simultaneously. This strategy features mild reaction conditions, good substrate compatibility, and excellent regioselectivity. The products obtained have the potential for further conversion into other valuable compounds. Initial investigations into the reaction mechanism suggest that it may proceed via a radical pathway. Notably, SOgen was proven as a uniquely effective SO2 surrogate in this transformation.

Copper-Catalyzed Trifluoromethylthio-arylsulfonylation of Styrene Derivatives via the Insertion of Sulfur Dioxide.

A copper-catalyzed four-component trifluoromethylthio-arylsulfonylation between styrene derivatives, AgSCF3, aryldiazonium tetrafluoroborates, and ex situ generated sulfur dioxide (from SOgen) is presented. This reaction features mild reaction conditions, good functional group tolerance, a broad substrate scope, good yields, and excellent diastereoselectivity. Preliminary mechanistic studies revealed that a radical process might be involved in this transformation.