Title : Synthesis of Natural Products Today and the Challenges of Tomorrow.
Speaker : Prof. Tushar Kanti Chakraborty, Indian Institute of Science Bangalore
Date : 06/03/2020, 5:30 PM (Friday), C.V Raman Hall, Second Floor.
Abstract: Synthesis of biologically active natural products remains as fascinating and challenging as ever. Chemical synthesis of natural products allows us to carry out structural modifications of molecules to improve their selectivity, potency and pharmacological properties that have made tremendous inroads in the drug discovery today. Semisynthesis of molecules having improved physiological properties is another niche area of synthetic organic chemistry. In addition, pruning the unrequired appendages from structurally complex natural products has given rise to many core pharmacophores with improved efficacies.While modern chemical biology approaches like polypharmacology for repurposing the already approved drugs or synthetic biology to make useful molecules by engineered bacteria / yeast are gaining strong footholds, synthetic organic chemists are also gearing up to meet the challenges of present age of scalability by equipping themselves with diverse skills. Discovery of new smart reactions and simplification of target molecules are some of the hallmarks of modern organic synthesis facilitating new drug discovery.
An intramolecular radical cyclization reaction, initiated by trapping a transient carbon radical generated by Ti(III)-mediated opening of an epoxide, has been extensively used by us to stereoselectively construct the polycyclic frameworks of many terpenoid natural products, especially [18.104.22.168]dioxafenestranes. The existence of the planarized distortion of the central quaternary carbon in these fenestranes away from its standard tetrahedral bond angle makes their synthesis a daunting task. Synthesis of some of these molecules like penifulvin A and asperaculin A using our Ti(III)-mediated radical cyclization as a key step to stereoselectively construct the most important central quaternary centers of these molecules will be presented.
References: 1) Nallasivam J. L.; Chakraborty, T. K. J. Org. Chem. 2019, 84, 16124-16138; 2) Khan, H. P. A.; Das, D; Chakraborty, T. K. J. Org. Chem. 2018, 83, 6086-6092; 3) Das, D.; Chakraborty, T. K. Org. Lett. 2017, 19, 682-685; 4) Das, D.; Chakraborty, T. K. Tetrahedron Lett. 2016, 57, 3665-3677. 5). Das, D.; Kant, R.; Chakraborty, T. K. Org. Lett. 2014, 16, 2618-2621; 6) Pulukuri, K. K.; Chakraborty, T. K. Org. Lett. 2014, 16, 2284-2287.
About the Speaker:
Dr. Tushar Kanti Chakraborty, FNA, FASc, FNASc and Professor, Department of Organic Chemistry, Indian Institute of Science joined IISc in January 2014 after serving as the Director of CSIR-Central Drug Research Institute, Lucknow.
Dr. Chakraborty had his early education in Presidency College, Kolkata from where he got his BSc (Honors) in Chemistry. He did his MSc in Chemistry at IIT Kanpur, got his Ph.D. from the same institute under the supervision of Prof. S. Chandrasekaran in 1984 and carried out postdoctoral studies at University of Pennsylvania in Prof. K. C. Nicolaou’s lab during 1984-1987. He joined IICT Hyderabad in March 1987 and in December 2008 he moved to CDRI, Lucknow as Director.
He is the recipient of the Shanti Swarup Bhatnagar Prize in Chemistry. He is also elected Fellows of INSA, IASc and NASI. He received the prestigious JC Bose Fellowship from SERB for ten years and is the recipient of several other awards like NASI-Reliance Platinum Jubilee Award in Physical Sciences, CRSI medals, Pt. Jawaharlal Nehru National Award in Science, etc.
He is presently the President of Indian Peptide Society and served / serves as member of the Editorial Boards / Editorial Advisory Boards of many journals, visited many countries and delivered invited / plenary / keynote lectures in many national and international symposia and conferences. Dr. Chakraborty specializes in the areas of organic synthesis, especially total synthesis of natural products; peptides and designer peptidomimetic molecules for potential therapeutic applications. He has published many papers and guided several students for Ph.D.