Catalytic Synthesis of Trifluoromethyl Cyclopropenes and Oligo Cyclopropenes

The synthesis of trifluoromethylated cyclopropenes is very important for applications in drug discovery and functional materials. In this report, we describe the application of readily available, chiral rhodium(II) catalysts in a highly efficient asymmetric cyclopropenation reaction of fluorinated donor-acceptor diazoalkanes using a broad variety of aliphatic and aromatic alkynes. Further studies highlight the unique reactivity of fluorinated donor-acceptor diazoalkanes in the synthesis of oligo-cyclopropenes. Subsequent C-H functionalization of trifluoromethyl cyclopropenes furnishes densely substituted cyclopropene frameworks and also allows the synthesis of bis-cyclopropenes.