Sequential activation of a-bonds : Intermolecular cascade annulation with migration and remote functionalization

Department of Chemistry, University of Calcutta, University College of Science, 92, Acharya Prafulla Chandra Road, Kolkata-700 009, India

E-mail : dkmchem@caluniv.ac.in

Department of Chemistry, Gobardanga Hindu College, Gobardanga-743 273, West Bengal, India

E-mail : maitisuklaghc@yahoo.co.in

Manuscript received 18 July 2013, accepted 20 July 2013

We demonstrate a new catalytic property of the lanthanide compound CeC1₃.7H₂O which sequentially activates N-H, sp² C-H and sp³ C-H a-bonds at ambient temperature. The powerful catalyst enables selective C-C and C-N bond-forming intermolecular cascade annulation between enamines and diaryl-1,2-diketone to afford functionalized 3,3- diaryl-3-pyrrolin-2-ones involving migration of an aromatic ring. We have also initiated a new multicomponent strategy utilizing readily available and inexpensive precursors and environmentally benign CeC1₃.7H₂O as an efficient catalyst under benign reaction conditions towards direct synthesis of several N-heterocycles including pentasubstituted 2- pyrrolinones and pyrroles. These observations provide new prospects and perspectives in a-bond activation process for easy access to functional molecules.