Dual photoredox/cobalt-catalyzed regioselective hydroalkoxylation of 1,3-dienes with alcohols

Abstract

Catalytic hydroalkoxylation of alkenes with oxygen-nucleophiles is of great interest and importance in synthetic chemistry but remains underdeveloped. Herein, we have developed a photoredox and Co-catalyzed regioselective hydroalkoxylation of 1,3-dienes with alcohols, which enables efficient access to valuable allyl ethers in good to excellent yields. The reaction features mild conditions, good functional group tolerance, and a wide substrate scope. The applicability of this reaction to the late-stage functionalization of relatively complex natural products and bioactive molecules further increases the utility of the developed methodology. Mechanistic studies suggest that the reaction involves a CoH-mediated hydrogen atom transfer (HAT) to 1,3-diene, followed by a radical-polar crossover process involving nucleophilic displacement of allylic cobalt(IV) with free alcohols. This reaction is an important addition to the repertory of transition-metal-catalyzed hydroalkoxylation of alkenes, providing a new strategy for the synthesis of valuable allylic ethers.