Diastereoselective 1,2-difunctionalization of 1,3-enynes enabled by merging photoexcited Hantzsch ester with chromium catalysis

Abstract

1,3-Enynes have been widely recognized as prevalent synthons for the construction of valuable allenes, 1,3-dienes, and propargylic derivatives. However, significant advancements have primarily focused on elucidating the ionic reaction mechanism. The selective difunctionalization of 1,3-enynes involving radicals remains an outstanding challenge in particular within the realm of radical 1,2-difunctionalization. Herein, we present a comprehensive account of the regio- and diastereoselective radical multicomponent 1,2-dialkylation of 1,3-enynes via photoexcited Hantzsch ester and chromium co-catalysis to furnish highly valuable homopropargylic alcohols. Our protocol shows excellent compatibility and 1,2-regioselectivity. Remarkably, this innovative approach obviates the need for external photocatalysts, stoichiometric metal reductants, or additional additives, offering a novel strategy for the valuable transformation of 1,3-enynes.