Copper-Catalyzed Regio- and Stereoselective Formal Hydro(borylmethylsilyl)ation of Internal Alkynes via Alkenyl-to-Alkyl 1,4-Copper Migration

Abstract

Catalytic reactions involving 1,n-metal migration from carbon to carbon enable a nonclassical way of constructing organic molecular skeletons, rapidly providing complex molecules from relatively simple precursors. By utilization of this attractive feature, a new and efficient synthesis of alkenylsilylmethylboronates has been developed by formal hydro(borylmethylsilyl)ation of unsymmetric internal alkynes with silylboronates under copper catalysis. The reaction proceeds regioselectively and involves an unprecedented alkenyl-to-alkyl 1,4-copper migration. The reaction mechanism has been investigated by a series of kinetic, NMR, and deuterium-labeling experiments.

Regioselective Condensation Polymerization of Propargylic Electrophiles Enabled by Catalytic Element-Cupration

“…We selected silylboronic esters, which have been widely used as a silyl anion surrogate via transmetalation for the proposed transformation. − To our delight, the adaptation of the hydrocupration-CPPE procedure with minor modifications smoothly yielded silyl-decorated PBDs ( P8 - 10 ) in good MW (Figure a). Predominant HT connectivity was assigned based on NMR spectroscopy analogously (Figure S31).…”