Regio- and stereoselective carbotrifluoromethylation of alkynes through syn-carboboration.

An efficient Cu-catalyzed protocol for the carbotrifluoromethylation of alkynes has been developed using Ruppert-Prakash reagent as the CF3 source. The reaction proceeds under mild conditions to deliver a broad range of β-trifluoromethylated alkenes with excellent regio- and stereoselectivities. The selectivity was achieved via a merge of Cu-catalyzed carboboration with subsequent trifluoromethylation of the resulting vinyl-borate.