Thianthrenium Salts Enable Safe, Versatile Cyclopropanation via Iron Catalysis
Researchers have developed a new method for synthesizing cyclopropanes using alkylthianthrenium salts as carbene precursors. Unlike traditional diazo compounds or diiodomethane, which pose significant safety risks, thianthrenium salts offer a safer profile with no detectable exotherm. The reaction, catalyzed by iron phthalocyanine, allows for diverse olefin and carbene partners, overcoming limitations of previous methods that restricted substrate scope. The approach also enables scale-up via mechanochemistry (ball milling) and extends to other carbene-transfer reactions like sigma-bond insertion.