Silicon-Tethered Strategy for Copper(I)-Catalyzed Stereo- and Regioselective Alkylboration of Alkynes

Stereoselective silicon-tethered
alkylboration of alkynes in the
presence of a copper­(I) catalyst and a diboron reagent provided the
corresponding cyclic alkenylboronates in high yields (up to 99% yield)
with excellent regio- and syn-selectivities (E/Z = <1:99). The products, which can
be considered as the formal alkyne intermolecular alkylboration products,
undergo subsequent selective derivatization, including ring opening,
to give functionalized trans-stilbene derivatives.