SYNTHESIS OF ORGANO-FLUORINE COMPOUNDS BY METAL COMPLEX- MEDIATED AND -CATALYZED TRANSFORMATIONS OF FLUORO-ALKENES AND FLUORO-ARENES By Nicholas Orlando Andrella Thesis submitted in partial fulfillment of the requirements for the Doctorate in Philosophy degree in Chemistry Ottawa-Carleton Chemistry Institute Faculty of Science University of Ottawa © Nicholas Orlando Andrella, Ottawa, Canada, 2019 Abstract The prevalence of fluorine in natural products is scarce. There are but a handful of compounds that have been discovered to date. This could be largely attributable to the occurrence of fluorine in nature as fluoride (F-). — One might recognize such nomenclature from the ingredients list on a toothpaste tube — In fact, naturally occurring fluoride is most commonly found as fluorite (CaF2) or cryolite (Na3AlF6). As such, the introduction of fluorine via biological pathways has been limited to use of aqueous F- (a very poor nucleophile). This fact — coupled with its naturally low concentration in water — has created the ripe conditions for this shortage. In a way this has proven fertile for synthetic chemists because nature has not yet evolved a method for the deconstruction of partially or fully fluorinated compounds. Considering the above, as synthetic methodologies for the construction of carbon-fluorine bonds became available, so too did the discovery of their valuable properties. So beneficial are these properties that C-F bond-containing compounds have become commonplace in many households throughout the world. For example, practically every home relies on these compounds for use in their refrigerators. Other examples of useful fluorinated materials include blowing agents, non-stick coatings, pharmaceuticals, agrochemicals, liquid crystals, and lubricants. With all these applications and seemingly easy availability of these compounds, it is interesting to learn that original synthetic methods are still being employed today. As such, the objective of this Thesis is to develop ‘greener’ routes for the synthesis of fluorocarbons. We hypothesized that by studying transition metal-fluoroalkyl complex-mediated reactions, a more efficient catalytic system could be developed. A foreseen complication arises from the ii thermodynamic stability of C-F, transition metal-F and transition metal-CRF bonds. Improvements to overcome these caveats include the use of first-row late transition metal complexes. Presented herein are additions to this body of knowledge by expanding on the reactivity of nickel, copper and silver fluoroalkyl complexes. The approach applied in this work, in line with ‘green’ chemistry principles, was to source readily available fluorinated reagents, i.e. fluoroalkenes and fluoroarenes, to reduce the number of steps for the synthesis of new fluorinated compounds. Chapter 2 builds on the well- established oxidative cyclization of C2 fluoroalkenes to nickel (0), which yields new C4 units. The use of a bulky N-heterocyclic carbene ligand was found to enhance reactivity by reducing the coordination number at nickel. Examples of room temperature Cα-F and Ni-CF bond activation and functionalization reactions are presented. Chapters 3, 4 and 5 re-examine the insertion of fluoroalkenes into silver and copper fluorides and hydrides. Building on precedent of addition reactions to hexafluoropropene, this fluoroalkene was examined first. In so doing, a versatile and inexpensive copper heptafluoroisopropyl reagent was developed (Cu-F addition to (CF3)CF=CF2. With easy access to new heptafluoroisopropyl complexes, they were systemically studied for their applications in catalysis. This revealed key features, particularly the lability of the M-hfip bond, which could be detrimental to catalytic reactions. As such, a nickel complex- mediated carbonylative heptafluoroisopropylation reaction and copper complex-mediated nucleophilic addition to electrophiles were developed. When a copper hydride was used instead, the in situ generated fluoroalkyl [Cu-H addition to (CF3)CF=CF2] was susceptible to β-fluoride elimination. Chapter 4 expands this methodology to achieve the catalytic consecutive hydrodefluorination of fluoroalkenes, demonstrating the scope and limitations of this system. Furthermore, the critical role of the phosphine ligand in accessing an L3Cu-H addition and iii unusual β-fluoride elimination mechanism is highlighted. However, tetrafluoroethylene proved resistant to this reaction because the fluoroalkyl resting state of this alkene, Cu-CF2CF2H, is unusually robust. Chapter 5 investigates the utility of this fragment and others in C(sp2)-RF cross-coupling and nucleophilic substitutions. With focus on new routes for late stage fluorination and examples of nickel (0) complex-catalyzed selective C-F bond functionalization reactions, Chapter 5, continues studies for low-temperature and DMAP-assisted conditions for aryl-F cross-coupling reactions with boronic acid esters. Lastly, Chapter 6 reviews the advances presented in this Thesis, provides a link to the expected lasting impacts and attempts to provide guidance to future research on transition-metal complexes in the synthesis of C-F or C-RF containing compounds. Moreover, with the introduction of a new hydrodefluorination technology, previously scarce fluoroalkenes (e.g. 1,2- difluoroethylene) can now be used more freely, potentially leading to the development of new refrigerants or materials applications. iv Acknowledgements The opportunity to continue my passion in organometallic chemistry, after my undergraduate studies, would not have been possible without the support and guidance from my family and colleagues. They are the crucial pillars to my foundation without which I could not have pursued my studies with zealot-like ferocity. My appetite for learning is huge and my attention span borders on zilch when I am absorbed in my work. I can only imagine what you all must have tolerated from me over these last few years. For this, I am eternally grateful. Prof. Tom Baker, thank you for recognizing my potential and being an exemplar of great leadership. Your open-door policy, your willingness to listen, and your positive and constructive criticism are always valued. Your patience in teaching me to own my work and moulding my writing style will be carried with me for the rest of my career. Finally, I will have the pleasure of joining the prestigious group of Baker alumni. Obtaining this status has also come with the pleasure of meeting so many from this community who also call themselves the same or will call themselves such soon. To Kaitie, Christian, Matthew, Graham, Mehdi, Uttam, Alex Daniels and Yahya. Writing this has reminded me of the support I got from you all. From hours helping me prepare presentations through to discussions about advances and direction for my research; my accomplishments are only as great as they are because of your backing. To Alex Sicard and Hassan, on top of all this you guys willingly took- up a desk next to me. Not only did we share lab space, we also shared a desk space where we were forced to listen to each other, if we liked it or not… for the whole day. I know that I can talk a lot so thank you for having the stamina and keeping up with me. I think, because of this, our friendship goes beyond the usual definition. Thanks also to Nancy and Karen, the two best v undergraduate students I could have worked with. With your hard work and determination, together we probed the frontiers of organometallic space. But most of all, “Thank you for making my time in the Baker lab memorable.” To Andrea, its unfortunate you spent such a short time here, we made quite the Italian trio. Thank you, for showing my wife and me around Bologna. Wherever our careers lead, I know we will stay in touch. To my family and friends, unbeknownst to you, you all helped carry me to the end. To Andrew, Marc, Matt, Ryan, Jordan, Hebert, Bianca and Michel; I don’t think I could have foreseen myself completing this body of work without our timeless friendships. The intermittent distractions that you guys brought to my ceaseless thinking on chemistry helped restore my calm; like the feeling of listening to waves break on a sandy beach or maybe a bit more like the relief of anxiety after booting up your PC from a crash and seeing the login screen again. To my Japanese colleagues, thank you for being such wonderful hosts. You were all so generous and hospitable, and I’m so grateful I had the opportunity to do research in your labs. To Fujimoto-san, thank you so much for all your help, I will never forget the delicious cake you made for my wife and me. To Ogoshi Sensei, your mentorship during my stay was invaluable. Your passion for chemistry is inspiring and it was truly an honour to work with you. To Ohashi Sensei, thank you for all the help in mounting my crystal and solving the structures… Oh and for the delicious natto. To Mike and Pam, it has been 29 years (25 years) that we have helped each other get to where we were going. You guys are the best and I wouldn’t wish for better siblings. I don’t think I can thank you enough… because you guys have put up with more things than I could ever write or am allowed to say here. vi To Mom and Dad, without you I could not have made it this far. You have taught me far more then what I could have ever learned through my studies. I am only an astute learner because Dad taught me patience and attentiveness. I am only a good presenter because Mom taught me to be uncompromisingly honest and authentic. I am only a good teacher because you both taught me confidence and passion. I am who I am because you provided me with the opportunity to be hard-headed, a trait you couldn’t have known would be fit for a chemist. Thank you, thank you, thank you. Most importantly, I have carried out the work in this Thesis on the back of a most special woman, my wife.