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Professor Manas K. Ghorai
PhD (NCL Pune)
Professor, Department of Chemistry
Research Interest
Aziridine and azetidine chemistry, Dianion chemistry, Memory of chirality, Organocatalysis
Indian Institute of Technology Kanpur
Kanpur - 208 016
Specialization
Synthetic Organic Chemistry
Education
PhD (1998), NCL Pune
Selected Publications
A Route to Highly Functionalized β-Enaminoesters via a Domino-Ring Opening-Cyclization-Decarboxylative Tautomerization Sequence of Donor-Acceptor Cyclopropanes with Substituted Malononitriles,Org. Lett., 16, 2204 (2014).
Synthesis of 3,5-Disubstituted Cyclohex-2-en-1-one via a Five-Step Domino Reaction Catalyzedby Secondary Amines: Formation of (E)-α,β-Unsaturated Methyl Ketones,Asian J. Org. Chem., 2, 1026 (2013).
An efficient synthetic route to carbocyclic enaminonitriles via Lewis acid catalysed domino-ring-openingcyclisation (DROC) of donor–acceptor cyclopropanes with malononitrile,aziridines", J. Org. Chem. 2013, 78, 2311.
Memory of Chirality (MOC) Concept in Imino-Aldol Reaction: Enantioselective Synthesis of α,β-DiaminoEsters and Aziridines,J. Org. Chem., 78, 2311 (2013).
A Synthetic Route to Chiral Indolines via Ring Opening/C−N Cyclization of Activated 2-Haloaryl-aziridines,J. Org. Chem., 78, 3867 (2013).
Domino Imino-Aldol-Aza-Michael Reaction: One-Pot Diastereo- and Enantioselective Synthesis of Piperidines,J. Org. Chem., 75, 7061 (2010).
Lewis Acid-Mediated Unprecedented Ring-Opening Rearrangement of 2-Aryl-N-tosylazetidinestoEnantiopure (E)-Allylamines,Org. Lett., 9, 5441 (2007).
Professional Experience
Post-doctoral research associate,Wuerzburg University, Germany, 1998-1999
Alexander von Humboldt fellow, University GH Siegen, Germany, 1999-2000
Post-doctoral research associate, Massachusetts Institute of Technology, USA, 2001-2002
Current Research
Prof. Ghorai's research interests lie in the area of
i) synthetic and mechanistic investigation of small ring aza-heterocycles,
ii) enolate and dianion chemistry, and
iii) asymmetric synthesis including natural products and drugs employing the concept of either memory of chirality, chiral pool or organocatalysis.
My group has demonstrated the MOC concept in imino-aldol reactions for the first time. We have been exploring MOC concept in a number of important chemical transformations e.g. aldol reaction, Michael reaction and many other domino processes.
We have established that the Lewis acid catalyzed nucleophilic ring-opening of 2-aryl-N-tosyl-aziridines or azetidines does proceed through an SN2-type pathway instead of a stable 1,3- or 1,4-dipolar intermediate, respectively, as invoked earlier in the literature. We further demonstrated that non-nucleophilic quaternary ammonium salts could be employed in controlling the racemization process and it could be possible to obtain the ring opening products from aziridines and azetidines with an external nucleophile in the presence of a non-nucleophilic Lewis acid with enhanced diastereo- and enantioselectivity.
This finding enabled us to design and develop new innovative and creative synthetic routes towards various non-racemic bio- and pharmacologically active acyclic and cyclic compounds of contemporary interest. Very recently, we have successfully applied the methodology for donor-acceptor (DA) cyclopropanes for the stereoselective synthesis of a number of carbacycles.
We have developed many new domino reactions e. g. domino-imino-aldol-aza-Michael, domino-aldol-Michael, domino-Michael-Michael via enolate anion and dianion chemistry. We have introduced a new concept, domino ring opening cyclization (DROC) for the stereoselective formation of carbacycles and aza/oxa- heterocycles employing activated aziridines, azetidines and DA-cyclopropanes with suitable nucleophiles. Our research group has efficaciously employed metal- and organocatalysts in the field of domino reactions as well. Overall our research activities have provided new directions to organic synthesis in general and asymmetric synthesis in particular.