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Application of the Picoloyl Group in Carbohydrate Chemistry University of Missouri, St. Louis IRL @ UMSL Dissertations UMSL Graduate Works 4-5-2019 Application of the Picoloyl Group in Carbohydrate Chemistry Michael Mannino University of Missouri-St. Louis, [email protected] Follow this and additional works at: https://irl.umsl.edu/dissertation Part of the Organic Chemistry Commons Recommended Citation Mannino, Michael, "Application of the Picoloyl Group in Carbohydrate Chemistry" (2019). Dissertations. 818. https://irl.umsl.edu/dissertation/818 This Dissertation is brought to you for free and open access by the UMSL Graduate Works at IRL @ UMSL. It has been accepted for inclusion in Dissertations by an authorized administrator of IRL @ UMSL. For more information, please contact [email protected]. Application of the Picoloyl Group in Carbohydrate Chemistry By Michael P. Mannino Master of Science (Chemistry), University of Missouri-St. Louis, May 2016 Bachelor of Science (Chemistry), University of Missouri-St. Louis, May 2014 A Dissertation Submitted to the Graduate School of the UNIVERSITY OF MISSOURI – ST. LOUIS in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in CHEMISTRY May, 2019 Dissertation Committee Prof. Alexei V. Demchenko, Ph.D. (Chair) Prof. Cynthia M. Dupureur, Ph.D. Prof. Christopher D. Spilling, Ph.D. Prof. Michael R. Nichols, Ph.D. ABSTRACT Application of the Picoloyl Substituent in Carbohydrate Chemistry Michael P. Mannino Doctor of Philosophy, University of Missouri – St. Louis Prof. Alexei V. Demchenko, Advisor Stereocontrol of glycosylation reactions is a constant struggle in the field of synthetic carbohydrate chemistry. The application of the picoloyl (Pico) substituent can offer numerous stereocontrolling avenues. The most popular application is the Hydrogen-bond-mediated Aglycone Delivery (HAD) method that provides excellent selectivity in the glycosylation of a variety of sugar substrates. The HAD method relies on the formation of an intermolecular hydrogen bond between the nitrogen atom of the Pico substituent on the glycosyl donor with the hydroxyl group of the glycosyl acceptor. This interaction provides a facial preference for the nucleophilic attack and hence provides powerful stereocontrol for the glycosidic bond formation. A significant utility of the HAD method has been previously demonstrated in the stereocontrolled α- glycosylation and multi-step synthesis of α-linked oligosaccharides. Described herein is the application of the Pico group to β-stereoselective synthesis of carbohydrates. Upon introducing new reaction conditions, we uncovered a new mechanistic pathway by which the Pico-substituted substrates may react. The in-depth mechanistic studies were designed to uncover the details of the new mechanistic ii pathway. Investigation of the reaction intermediates by high-field NMR led to the identification of a quasi-stable glycosyl triflate that was deemed to be the key intermediate of the reaction. This study demonstrates a novel method for glycosyl triflate formation that may have broad applications in the field of organic chemistry. In the application to the β-stereoselective synthesis of glycans, the glycosyl triflate intermediate was credited for excellent stereoselectivity achieved. iii ACKNOWLEDGEMENTS First and foremost, I would like to acknowledge my mentor and boss Professor Alexei Demchenko. You have always nurtured my curiosity in the lab but have also been able to tell me what I need to hear and not what I want to hear. I know I have leaned on you heavily these last few weeks but I have learned a lot from you and I intend to keep learning in the future and stay in contact. You have also taught me that it isn’t so hard to have a good time with your boss ... SUCHIAMO! I also need to thank my two mentors in the lab Dr. Prithika Yasomanee and Salvo Pistorio. Prithika trained me tough but fair and always pushed me to do my best. It is because of her that I have the strong work ethic I do today. Salvo didn’t train me much on lab techniques but he did teach me how to deal with people professionally. He taught me how to treat your coworkers with compassion and that every now and then you need to talk to someone when times are tough. Above all he taught me that just because it’s research, doesn’t mean you can’t be a positive person and laugh. I also want to thank Dr. Yashpal for always offer intellectual conversations about chemistry (not easy to find) and for being an immaculate example of hard work. I want to thank all my past and present lab mates, especially Scott Geringer, Mithila Bandara (and the rest of her 8 names), and Catherine Alex. We all have fun together and I truly enjoy your company. I also need to thank my parents, especially my mother who has always been my biggest fan, and my brothers and sisters who motivate me to be better all the time and who give me a web of support that is unmatched. I would also like to thank Peter Higgs ... The ferret. Very tough days were had together. You’ve ran away and come back home, more impressive than any boson! The final personal thank you goes to my incredible girlfriend Rachel Michelle Schafer. You are the only one who knows what I am going through all the time. You have been there for me when research drives me crazy and you take great joy when I finally succeed. You are amazing and I love you. My last statement is to glycoworld: We are pushed by mentor and peer alike and laziness is looked down upon. Knowledge is powerful but not as much having an open mind. Comradery and accountability make our lab efficient and dynamic. These qualities are exhibited by our leader and by our students. I am proud to have been trained in glycoworld. iv LIST OF ABBREVIATIONS Å ............................................................................................................................Ångström Ac ...............................................................................................................................Acetyl All .................................................................................................................................Allyl AgOTf ...........................................................................Silver(I) trifluoromethanesulfonate AgOTs ......................................................................................Silver(I) p-toluenesulfonate BCN............................................................................................................. o-Cyanobenzyl BF3-OEt2 ......................................................................................Boron trifluoride etherate Bn ...............................................................................................................................Benzyl BnBr ............................................................................................................Benzyl bromide Boc ....................................................................................................tert-Butyloxycarbonyl Br2 ...........................................................................................................................Bromine Bz .............................................................................................................................Benzoyl BzCl............................................................................................................Benzoyl chloride °C ..................................................................................................................Degree Celsius CaH2 ...........................................................................................................Calcium hydride CDCl3 ..............................................................................................................Chloroform-d COSY.......................................................................Homonuclear correlation spectroscopy Cu(OTf)2.....................................................................Copper(II) trifluoromethanesulfonate d ................................................................................................................................Doublet DABCO ................................................................................1,4-Diazabicyclo[2.2.2]octane v DCE ........................................................................................................1,2-Dichloroethane DCM ......................................................................................................... Dichloromethane dd ...........................................................................................................Doublet of doublets DDQ ................................................................. 2,3-Dichloro-5,6-dicyano-p-benzoquinone DMAP .........................................................................................4-Dimethylaminopyridine DMTST.....................................Dimethyl(methythio)sulfonium trifluoromethanesulfonate DMSO ....................................................................................................Dimethyl sulfoxide EDC ....................................................1-Ethyl-3-(3-(dimethylamino)propyl)-carbodiimide Et ..................................................................................................................................Ethyl Et2O ..................................................................................................................Diethyl ether EtOAc..............................................................................................................
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