Rapid access to C2-quaternary 3-methyleneindolines via base-mediated post-Ugi Conia-ene cyclization.

Highly efficient synthesis of diverse 2,2-disubstituted 3-methyleneindoline derivatives through a one-pot base-promoted post-Ugi 5- exo -dig "Conia-ene"-type cyclization has been disclosed. The mechanism study indicates that an intramolecular hydrogen bond may play a vital role in this process. The antiproliferative evaluation of cancer cell lines reveals that this protocol provides practical use in the green synthesis of bioactive compound libraries.