One-Pot Carboboration of Alkynes Using Lithium Borylcyanocuprate and the Subsequent Suzuki-Miyaura Cross-Coupling of the Resulting Tetrasubstituted Alkenylborane

We have developed a one-pot carboboration of internal alkynes using lithium borylcyanocuprates 3. Isolation of single crystals of 3 center dot(thf)(3) enabled us to estimate its structural and spectroscopic features. Simple mixing of 3 with ester-substituted alkynes and alkynylarenes was followed by trapping of the resulting intermediate with electrophiles to give tetra-substituted borylalkenes 4, 5, and 8 in moderate to good yields. Ligand exchange of 8ba from diamine to pinacol allowed us to explore further application of obtained pinacol ester 10ba to subsequent Suzuki-Miyaura cross-coupling reactions to give all-carbon substituted alkene 9ba.