Copper(I)–Thiazol-2-ylidenes: Highly Reactive N-Heterocyclic Carbenes for the Hydroboration of Terminal and Internal Alkynes. Ligand Development, Synthetic Utility, and Mechanistic Studies
hydroboration of alkynes to afford trisubstituted vinylboronates by β-hydroboration of internal alkynes or terminal vinylboronates by β-hydroboration of terminalalkynes. Application to the late-stage modification and detailed mechanisticstudies on the catalyst structure and activation are presented. Most crucially, Cu(I)–thiazol-2-ylidenes show a much higher β-selectivity in the hydroboration of alkynes than