Experimental and Theoretical Investigations of Copper‐Catalyzed Chemo‐, Regio‐, and Stereoselective <i>cis</i> ‐Hydroboration of 1,3‐Enynes

The mechanistic details of the chemo‐, regio‐, and stereoselective cis ‐hydroboration of 1,3‐enynes were investigated using X‐ray crystallography, kinetic analysis, and density functional theory (DFT) calculations. The kinetic analysis revealed that the reaction is first order in enyne, zeroth order in HBpin, and fractional order in the catalyst. Our studies suggest that a cyclic CuHBpinOAc complex is an off‐cycle species (via DFT analysis) that contributes to the experimentally observed fractional rate order regarding the catalyst. Experimental and computational data suggest that hydrocupration is rate‐limiting and essential for achieving selectivity.