Research Overview :

Prof. Khan's research group significantly contributed towards development of useful methodologies employing ruthenium-catalysis (J. Am. Chem. Soc., 2000, 122, 9558). Keeping in mind the broad scope of ruthenium-catalysis, he developed an environmentally benign, recyclable supported catalyst which not only is highly efficient but also could be used even with house-hold bleach as stoichiometric cooxidant (Journal of Catalysis 2005, 230, 438). The ruthenium catalyzed chemistry developed by him is described in specialized books such as Modern Oxidation Methods (Wiley-VCH, Weinheim, 2004; page 167), edited by J.-E. B'ckvall and Ruthenium in Organic Synthesis (Wiley-VCH, Weinheim, 2004; page 66) edited by Shun-Ichi Murahashi. He also developed novel applications of metals such as indium (Org. Lett., 2002, 4, 1015 and Chem. Eur. J. 2004, 10, 2507), zinc (Tetrahedron Lett. 2009, 50, 3394) in organic synthesis. The contributions made on indium chemistry were pedagogically important to find a mention in March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 6th Edition (page: 1312). Synthesis of enantiomerically pure compounds is an important area of research. In this direction, he demonstrated useful technologies to synthesize optically pure building blocks from chiral pool (Org. Lett. 2008, 10, 3029).

Prof. Khan's research contributions added a new dimension to the rich chemistry derived from cycloaddition reactions of 5,5-dimethoxytetrachlorocyclopentadiene and its bromo analogue. He demonstrated for the first time that the two sets of halogens (bridgehead or vinylic) in the cycloaddition adducts could be selectively utilized either to make C-C bonds at the bridgehead or to transform the 1,2-dihaloakene moiety to extremely versatile diketone building blocks. He demonstrated the application of these useful methodologies for constructing biologically important natural products or intermediates such as spiro lactams (J. Org. Chem., 2003, 68, 4556), trans- hydrindanes (J. Org. Chem., 2004, 69, 5295), pentenomycin (Tetrahedron Lett. 2006, 47, 5251) and neplanocin A (J. Org. Chem., 2007, 72, 7011). Further, employing the novel methods developed in his laboratory Prof. Khan demonstrated the synthesis of aesthetically pleasing, strained polycyclic unnatural compounds possessing oxabridges (J. Am. Chem. Soc., 2002, 124, 2424 and J. Org. Chem., 2005, 70, 7565). This led him to design a novel hybrid of azacrown ether-oxabridged fluorogenic chemosensor which showed higher affinity towards transition metal ion Zn2+ and heavy metal ion Hg2+ compared to the parent azacrown (Chem. Commun. 2009, 2399). In addition, several constrained systems such as diquinane-based bis-gamma-lactones (Tetrahedron Lett. 2006, 47, 7567), bowl-like molecules (Tetrahedron Lett. 2007, 48, 207) and 9-oxa-noradamantane derivative, an aesthetically pleasing 'oxa-basket' (Tetrahedron Lett. 2009, 50, 5751) were synthesized. Utilizing the indigenously developed methodologies, his group is engaged in design and synthesis of optically pure polycyclic amines and their organocatalytic screening (Tetrahedron Lett. 2008, 49, 6111).

With growing environmental concerns regarding the usage of volatile organic solvents, there has been a greater emphasis on development of greener technologies in the recent years. In this regard, Prof. Khan's research group is engaged in developing recyclable catalytic systems for C-C bond forming processes employing ionic liquids as reaction media (Tetrahedron Lett. 2004, 45, 3055). He demonstrated a hitherto unprecedented moderating effect of oxygen on zinc metal during reduction of nitro arenes to their corresponding azoxy derivatives using ionic liquid as recyclable solvent Tetrahedron Lett. 2009, 50, 3394. His research group achieved the total synthesis of pentenomycin, paracaseolide A, cis- and trans-neocnidilides, brominated alkaloids like wilsoniamines A and B, amathamide D, convolutamine F, H and lutamide A, C, ianthelliformisamine A, and formal synthesis of neplanocin A and varitriol.