H <sub>2</sub> -Mediated Copper-Catalyzed C–C Coupling Reactions: Selective Formation of Skipped Dienes
Lea T. Brechmann, Benyapa Kaewmee, Johannes F. Teichert
Abstract
A simple copper(I)- N -heterocyclic carbene complex facilitates a H 2 -mediated C–C coupling reaction of internal alkynes and allylic chlorides. The catalytic protocol delivers the corresponding 1,4-dienes (skipped dienes) with high chemo-, regio-, and stereoselectivity without any isomerization to the thermodynamically more stable 1,3-dienes or over-reduction to the corresponding alkanes. The H 2 -mediated C–C coupling reaction allows for the exploitation of “copper hydride catalysis” with H 2 as the terminal reducing agent and source of hydrides for forging C–C bonds. In this way, this approach gives rise to C–C bond-forming reactions with a 3d metal without the need for a stoichiometric organometallic reducing agent.