Rh-catalyzed asymmetric cyclopropanation of benzofurans with trifluoromethyl N-triftosylhydrazones.

• Asymmetric cyclopropanization of benzofuran was achieved in the presence of chiral rhodium catalysts. • Using N -triftosylhydrazones as the safe diazo-compound surrogate, the reaction conditions are mild and safe. • DFT calculations explain the reason behind the high enantioselectivity during this cyclopropanation reaction. An asymmetric dearomative cyclopropanation of benzofuran has been accomplished by a novel catalytic method that relies on using trifluoromethyl N -triftosylhydrazones as carbene sources in the presence of a chiral rhodium catalyst. This reaction produces chiral trifluoromethyl-tethered 2,3-disubstituted benzofuran cyclopropane, which carries versatile pharmacophores 2,3-dihydrobenzofuran and trifluoromethyl-substituted quaternary carbon centers. Notably, this process offers distinct advantages over other existing approaches due to being step-economic and eliminating green-gas N 2 as a harmless coproduct. DFT calculations explain the reason behind the high enantioselectivity during this cyclopropanation reaction. Asymmetric dearomatization of benzofuran was achieved using N -triftosylhydrazones as a carbene source under rhodium catalysis. This efficient asymmetric transformation proceeds under mild and convenient conditions with significant functional group tolerance, providing optically pure benzofuran cyclopropane with a trifluoromethylated quaternary stereocenter. [Display omitted] [ABSTRACT FROM AUTHOR]