Research Projects

Organocatalysis by N-heterocyclic carbenes (NHCs) has become a powerful tool for making C-C and C-heteroatom bonds, resulting in the synthesis of various organic compounds, including heterocycles. NHCs have the remarkable ability to inverse the polarity, known as umpolung, of electrophilic carbon centers to nucleophilic ones, which is known as Breslow intermediate. Classical examples of NHC-catalyzed transformations involving umpolung of aldehydes via Breslow intermediates include benzoin and Stetter reaction. However, the use of imines for this purpose has received limited attention. The proposal aims to develop novel NHC catalytic strategies involving imine umpolung and Michael acceptor umpolung, resulting in the synthesis of valuable heterocycles of biological interest. This includes designing and developing NHC catalyzed imine umpolung-oxidation-cyclization cascades for diverse heterocycles involving lactamization or having an amide functional group exo to the formed heterocycles. The proposal also proposes designing NHC catalytic umpolung transformations using pyridinium salts tethered with Michael acceptors that provide a nucleophilic center under the influence of NHC, which in turn adds to the pyridinium moiety to provide pyridine fused bicyclic/tricyclic molecules. Additionally, the proposal proposes developing intramolecular conjugate addition reactions of nucleophiles generated through NHC catalyzed imine umpolung for the synthesis of a variety of O- and N-heterocycles. The study aims to demonstrate the potential applications of the developed methods and provide promising NHC catalytic strategies in advanced synthetic organic chemistry.