An Organometallic Umpolung Approach for Iron-Mediated Propargylic C-H Etherification.

Propargylic ethers serve as useful intermediates for the synthesis of a variety of complex targets. However, propargylic substitution of prefunctionalized alkyne starting materials remains the dominant method for the synthesis of propargyl ethers, while direct etherification of simple alkynes via propargylic C-H functionalization remains largely underreported. Herein, we report an organometallic umpolung approach for iron-mediated C-H propargylic etherification. A telescopic protocol for iron-mediated C-H deprotonation followed by mild oxidative coupling with alcohols enabled the use of simple or functionalized alkynes for the expedient synthesis of propargylic ethers with excellent functional group compatibility, chemoselectivity and regioselectivity.