Organoboron‐ and DMSO‐Mediated Ring‐Opening of Cyclopropenones for the Acrylation of Alkyl (Pseudo)Halides

ABSTRACT Herein, we disclose a three‐component tandem reaction wherein organoboron and DMSO mediate the ring‐opening of cyclopropenones to trigger the subsequent acrylation of alkyl (pseudo)halides. A series of cyclopropenones with various aryl groups, together with diverse alkyl (pseudo)halides bearing primary, secondary, and tosylate‐based leaving groups, are converted into trisubstituted E ‐acrylates under transition metal‐free conditions. Using B 2 pin 2 as the promoter and Cs 2 CO 3 as the base in DMSO at 40°C, the desired products are obtained in moderate to excellent yields (up to 99%) without the need for exclusion of air or moisture. DMSO serves as both the solvent and the oxygen atom source, while trace amounts of water in the reaction system donates the alkenyl hydrogen atom. The reaction exhibits high functional group tolerance and good scalability, and is applicable to late‐stage modification of pharmaceuticals such as indomethacin and naproxen. Furthermore, mechanistic investigations, including isotope labeling experiments and control studies provide insights into the possible mechanistic steps. This formal three‐component coupling joins two electrophiles via an exogenous oxygen atom, thus bypassing the need to pre‑match electrophiles with nucleophilic partners.