Selective Synthesis of 5‐Alkylated and 5‐Alkenylated Chromones via Catalytic C‐H Coupling of Chromones with Allyl Alcohols

Herein, we describe two types of C5 functionalization reactions of chromones with allyl alcohols. Diverse 5‐substituted chromones can be produced by modulating the catalysts in these reactions: Rh(III) results in the formation of 5‐alkylated chromones, and Ru(II) furnishes 5‐alkenylated products. We also achieve further functionalizations of these 5‐substituted chromones, which demonstrates the superiority of this method. Notable features of these new methods include readily available precursors, tunable reactivity, exclusive C5‐selectivity, and easy derivatization of products. The selective preparation of 5‐alkylated and 5‐alkenylated chromones from readily accessible substrates using Rh(III) and Ru(II) catalysts has been successfully developed. Forty‐one examples of the target compounds were obtained in up to 95 % yield.