Cu-Catalyzed Regio- and Stereodivergent Chemoselective sp2/sp3 1,3-and 1,4-Diborylations of CF3-Containing 1,3-Enynes

CF3-containing multi-borylated compounds are intriguing molecules that can serve as building blocks and readily transform into various significant molecules. Here, a series of Cu-catalyzed assembly of 1,3- and 1,4-diborylated compounds bearing CF3 group starting from readily available 1,3-enynes has been developed. This is the first example that could approach two different C-B bonds from 1,3-enynes despite their conjugated structures. The unprecedented regio- and stereodivergent sp(2)/sp(3) 1,3- and 1,4-diborylations of 1,3-enynes were regulated by ligands, bases, and solvents. Most remarkably, the well-known defluorination of CF3 group on alkenes upon nucleophilic additions was completely suppressed in our systems, leaving a valuable CF3 group intact. Moreover, homopropargylic boronates and homoallenyl boronates as the key intermediates for the above transformations were also obtained after fine-tuning the reaction conditions. Both experimental and theoretical calculations elucidate the E/Z selectivities and regioselectivities in these transformations.