Research Projects

In the past decade, there has been a revolution in the field of synthetic organic method development with the discoveries of various novel open-shell radical intermediates that unravelled new modes of bond activation resulting into the development of innovative synthetic methods, otherwise unimagined earlier. A newer addition to this list is the phosphinium radical cation which gathered attention from organic chemists in the last few years. However, the full potential of these powerful intermediates is yet to be uncovered as they mostly were used to generate carbon-centered, nitrogen-centered radicals and hydrogen atom through a variety of single bond activation which resulted into acylation, alkylation, hydrogenation, amination and cyclization reactions. This proposal promises to make the P-radical cations a more general and versatile activation tool by realizing underexplored carbon-carbon multiple bond activation with them, leading to the modular synthesis of important carbocycles, heterocycles, and functionalized hydrocarbons that are highly useful building blocks in organic synthesis. Specifically, we plan to develop photocatalyzed or photoinduced redox reactions where a trivalent phosphorus compound (phosphine/phosphite) will be used as a mediator or a catalyst, thereby activating carbon-carbon multiple bonds to build molecular complexity around them with aldehydes, ketones, imines and alkanes as the other reacting partners. Within this reaction framework, we envisage a photochemical phosphine-mediated modular synthesis of cyclopropanes and dienes via deoxygenative alkene/carbonyl condensation. Under similar reaction conditions, when we replace the carbonyl component with in situ formed imine, the final product is expected to be azetidines via a formal aza Paternò–Büchi reaction. We also plan to undertake, as part of this project, visible-light aided and phosphine-mediated bis-alkylation and hydroalkylation of alkynes with alkanes and carbonyls serving as alkyl group surrogates. This will give us access to diversely functionalized olefins in a modular fashion. The successful realization of the planned project will see a conceptual advancement in the field of radical redox chemistry, in discovering the true dual activation ability of phosphinium radical cations through novel intermediates with orthogonal reactive centers. It will lead to the development of mild and sustainable photochemical methods for the synthesis of important building blocks such as cyclopropanes, dienes, azetidines and alkenes in a new modular way by using easily accessible and bench-stable aldehydes, ketones, amines and feedstock chemicals (olefins, alkynes and alkanes) as starting materials. Additionally, we also plan to extrapolate our methodology to demonstrate its application in the synthesis of 1,3-diene based aggregation-induced emission (AIE) luminogens and azetidine-based pharmaceutically active compounds, in the future.