From C₁ to C₃: Copper‐Catalyzed <i>gem</i>‐Bis(trifluoromethyl)olefination of α‐Diazo Esters with TMSCF₃

Abstract

A Cu-catalyzed gem-bis(trifluoromethyl)olefination of α-diazo esters, using TMSCF₃ as the only fluorocarbon source, has been developed and provides an exquisite method to access gem-bis(trifluoromethyl)alkenes. This unprecedented olefination process involves a carbene migratory insertion into "CuCF₃ " to generate the α-CF₃ -substituted organocopper species, which then undergoes β-fluoride elimination and two consecutive addition-elimination processes to give the desired products. The key to this efficient one-pot C₁ -to-C₃ synthetic protocol lies in the controllable double (over single and triple) trifluoromethylations of the gem-difluoroalkene intermediates.