(posted on Wednesday, April 4, 2018)
Our April 2018 general meeting is the annual Crano Memorial Program and will be held on Monday, April 30. Dr. T.V. (Babu) Rajanbabu of The Ohio State University will be the featured speaker for both an afternoon lecture at The University of Akron and an evening program at the Rosemont Country Club in Fairlawn.
Area college and university outstanding chemistry juniors will be recognized during the evening program.
2:30 PM, Mary Gladwin Hall room 111, The University of Akron
Catalytic Enantioselective Synthesis Using Feedstocks
Rosemont Country Club /Fairlawn, OH
Serendipity Still Rules and Conjectures Matter. From Group Transfer Polymerization to Ethylene Fixation
5:30 pm Social hour, 6:30 PM Dinner, 7:30 PM lecture
Both programs are free and open to the public; however, dinner reservations are required and must be made by noon on Monday, April 23. Please contact Walter Salamant (firstname.lastname@example.org) to make reservations. Cost is $25 for professionals, $10 for students.
RajanBabu had his early education in India, at Kerala University and the Indian Institute of Technology (Madras) respectively. He obtained a Ph. D. degree from The Ohio State University working with Professor Harold Shechter, and was a postdoctoral fellow at Harvard University with Professor R. B. Woodward. He then joined the Research Staff of DuPont Central Research and Development becoming a Research Fellow in 1993. He returned to Ohio State as a Professor of Chemistry in 1995 and currently holds the Kimberly Chair. He has published over 150 publications in leading journals including J. Am. Chem. Soc., Angew. Chem. Int. Ed., Chem. Sci., Science and 13 US patents. His research interests are in New Methods for Stereoselective Synthesis, Green Chemistry, Enantioselective Catalysis, Multicomponent Cyclization methods, Free Radical Chemistry and Natural Product Synthesis.
One of the major challenges facing organic synthesis in 21st century is the utilization of abundantly available carbon sources for fine chemical synthesis. The dual problems of activation of thermodynamically stable precursors and their stereoselective incorporation pose new challenges, solutions of which may have broader implications in homogeneous catalysis, and, at a practical level, how we synthesize/manufacture chemical intermediates. This talk will deal with two catalytic enantioselective reactions developed in our laboratories for the synthesis of value added intermediates from simple prochiral substrates, and, ethylene or methyl acrylate, two feedstock carbon sources. Substrates such as vinylarenes, cyclic and acyclic 1,3-dienes and strained alkenes undergo efficient heterodimerization with ethylene under catalysis by complexes of Ni, Co and Ru. Yields up to 99% can be realized for several of these substrates. Using chiral phospholanes, phosphinites and finely tuned phosphoramidites as ligands, enantioselectivities greater than 95% enantiomeric excess can be obtained for several substrates. Examples of how ligand tuning, properties of the counter ions and reaction conditions affect the yields and selectivities of these reactions will be illustrated. One major application of this chemistry is for the installation of an exocyclic stereocenter using a 1-vinylcycloalkene motif. These discoveries open expeditious routes to several biologically relevant classes of compounds including 2-arylpropionic acids (e.g., ibuprofen, naproxen), 1-arylethyl amines, steroid derivatives with uncommon D-ring side-chains, helioporins, pseudopterosins and analogs, and pyrrolidinoindolines such as physostigmine and phenserine, which contain all-carbon benzylic quaternary centers.
[Some leading references: (i) ‘Hydrovinylation Reactions in Organic Synthesis’, Comprehensive Organic Synthesis, 2nd edition, Vol. 5, Oxford: Elsevier; 2014. pp. 1582-1620. DOI: 10.1016/B978-0-08-097742-3.00533-4. (ii) Chem. Sci. 2015, 6, 3994. DOI: 10.1039/c5sc00929d. (iii) ‘Asymmetric Catalysis with Ethylene, Synthesis of Functionalized Enolates’, J. Am. Chem. Soc. 2015, 137, 14268. DOI: 10.1021/jacs.5b10364] (iv) ‘Catalytic Enantioselective Heterodimerization of Acrylates and 1,3-Dienes’, J. Am. Chem. Soc. 2017, 139, 18034.
This talk will deal with examples from the speaker’s research, first at DuPont Central Research, and, later at The Ohio State University, where accidental discoveries and conjectures, sometimes wrong, led to significant advances in organic synthesis.