We are an Organic synthesis group. We develop highly novel methods for the preparation of complex bioactive molecules. Our core research activity at CBMR include:
- Development of green methods for organic synthesis using NHC & Hypervalent Iodines
- C-H bond functionalization using organocatalysis
- Medicinal Chemistry (Drug Discovery)
Over the last one and half decade or so, organic molecules-catalyzed reactions have taken a centre stage in the field of organic synthesis. These molecules have emerged as an alternate to metal-based catalysts. These organocatalytic modes of activation are preferred as the reactions are greener, less sensitive to moisture and often cost-effective over metal-ligand based reactions. Intriguing features and success of these small organic molecules is the fundamental principle of our group’s research interests.
N-Heterocyclic Carbene Catalysis:
The remarkable ability of N-heterocyclic carbene (NHC)-based organocatalysts to reverse the normal mode of reactivity of aldehydes/imines is the foundation principle of their success in the field of organocatalysis. Chiral NHCs has been widely used for unconventional access to various enantioselective heterocycles. NHCs can catalyze transformations proceeding via the umpolung or nonumpolung mode. Such properties of these small organic molecules drives the focus of our group on further exploration of unprecedented enantioselective transformations.
Highlighted Publication: The N-Heterocyclic Carbene (NHC) catalyzed direct access to enantioenriched 4-phosphorylated δ-lactones from β-phosphorylenones and enals has been achieved. The sterically demanding β-phosphonate-substituted enones, having competing regiomeric reaction centres, have remained elusive so far in intermolecular cycloaddition reactions under NHC catalysis. All the products were obtained in excellent yield and enantioselectivity. These phosphorylated δ-lactones could be transformed to the challenging multi-functionalized chiral esters and amides loaded with β-ketophosphonate functionality. (https://doi.org/10.1039/D0CC03204B)
Highlighted Publication: A one-pot, stereoselective construction of 2,3- dihydroxy-2,3-diaryltetrahydrofurans has been achieved via N-heterocyclic carbene (NHC)/base-mediated domino reactions of aldehydes and vinyl selenone. The products containing two contiguous quaternary hydroxyl functionalities among the three stereocenters are obtained advantageously as either acetals or ketals through the formation of five new chemical bonds in a single operation. This report constitutes an altogether different reactivity of vinyl selenone in comparison with the corresponding sulfones and phosphonates under NHC/ base-mediated reactions. (https://doi.org/10.1021/acs.orglett.6b03501)
Hypervalent Iodine Catalysis:
Chiral hypervalent iodines (CHI’s) have more recently gained tremendous attention due to their intrinsic properties like, its highly electrophilic nature coupled with an excellent leaving ability of iodoaryls(III) which enables them to induce exclusive rearrangements through aryl migration, ring-expansion or ring-contraction to generate complexity and new stereocentres in a single step operation. With chiral hypervalent iodines, much of the success has come for the direct functionalization of the olefinic double bonds. However, stereoselective rearrangement through a migration of one of the substituents on the double bond has still tasted very limited success. The easy handling, nontoxicity, mildness, green oxidants, and high stability are some prevalent features of these reagents which allows our group’s interests in further exploring this unprecedented and exciting branch of organocatalysis for enantioselective transformations.
Highlighted Publication: The stereoselective oxidative rearrangement of disubstituted unactivated olefins has been achieved using hypervalent iodine(III) reagent. The aryl group undergoes 1,2-migration to give tert-α arylated aldehydes (as acetals). The preparation of these aldehydes/acetals, especially containing a tert-benzylic stereocentre, has remained challenging. This migration-based method provides a complementary approach over the known α-substitution-based methods for accessing this class of molecules. (https://doi.org/10.1021/acs.joc.0c00347)