No abstract

Installation of an alkyl chain at a specified position in the aromatic ring via metal-free catalysis is very important. In this regard, we have developed a facile metal-free, extremely selective, user-friendly, environmentally benign and costeffective Friedel-Crafts (FC) alkylation protocol for 2-oxindoles and anilines with donor-acceptor cyclopropanes. Real-time NMR studies reveal that the transformation is governed by the cooperative catalysis of Brønsted acid (TfOH) and HFIP, which facilitates the nucleophilic attack on donor-acceptor cyclopropanes from 2-oxindoles and anilines.