Regioselective and Redox-Neutral Cp*IrIII -Catalyzed Allylic C-H Alkynylation

Abstract

Herein, we report a Cp*Ir^III -catalyzed highly regioselective and redox-neutral protocol for the construction of 1,4-enynes from unactivated olefins and bromoalkynes via intermolecular allylic C-H alkynylation. The developed mild reaction conditions tolerate a broad range of common functional groups, even enabling selective alkynylation of allylic C-H bonds in the presence of other prominent directing groups. Mechanistic experiments including the isolation of a catalytically active Ir^III -allyl species support an intermolecular allylic C-H activation followed by an electrophilic alkynylation.

Keywords: 1,4-enynes.; alkynylation; allyl-iridium complex; allylic C−H activation; regioselectivity.