Alkylation of 1,2,5-Trisubstituted Pyrroles with Donor–Acceptor Cyclopropanes

Despite their inherently high nucleophilicity, pyrroles have rarely been explored in Friedel-Crafts-type alkylation reactions with donor-acceptor cyclopropanes (DACs). Herein, we report the first examples of such reactions of 1,2,5-trisubstituted pyrroles using DACs. Catalyzed by Sc(OTf)₃, the reaction provides efficient access to 1,2,3,5-tetrasubstituted pyrroles─an important class of bioactive compounds─in yields up to 93%. As anticipated, the C3 position of the pyrrole consistently outcompetes other potential nucleophilic sites, including tethered electron-rich arenes and indoles. Thus, this work not only expands the synthetic utility of DACs but also offers a powerful new tool to access diverse and complex pyrrole scaffolds.