Copper-Catalyzed Cyclopropenation of Alkynes with Difluoromethyl Carbene
Yong Yang , Paramasivam Sivaguru , Qingmin Song , Zhaohong Liu , Yong Ji , Wei Song , Karunanidhi Murali , Jacek Mlynarski , Xihe Bi
Chinese Journal of Chemistry ›› 2025, Vol. 43 ›› Issue (15) : 1833 -1840.
Copper-Catalyzed Cyclopropenation of Alkynes with Difluoromethyl Carbene
The [2+1] cycloaddition of alkynes with fluoroalkyl carbenes represents the most straightforward approach for constructing fluoroalkylated cyclopropenes. However, until now, this strategy has not been applicable to difluoromethyl carbene, as its precursor, difluoromethyl diazomethane, tends to undergo [3+2] cycloaddition with alkynes to form pyrazoles. This study presents the first example of copper-catalyzed cyclopropenation of alkynes with difluoromethyl carbene, employing difluoroacetaldehyde triftosylhydrazone as the carbene precursor. A wide range of internal and terminal alkynes, featuring diverse functional groups, were efficiently converted into the corresponding difluoromethyl cyclopropenes in good to high yields. Mechanistic investigations, supported by DFT calculations, revealed that the bulky TpBr3Cu(NCMe) catalyst plays a pivotal role in facilitating the cyclopropenation of alkynes with difluoromethyl carbenes via a concerted pathway.
Cyclopropenation / Cycloaddition / Alkynes / Carbenes / Difluoromethyl cyclopropenes / Copper catalysis / Triftosylhydrazone / Density functional calculations
2025 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
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