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Transition Metal Complexes of Oxazolinylboranes And Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2012 Transition metal complexes of oxazolinylboranes and cyclopentadienyl-bis(oxazolinyl)borates: Catalysts for asymmetric olefin yh droamination and acceptorless alcohol decarbonylation Kuntal Manna Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Inorganic Chemistry Commons Recommended Citation Manna, Kuntal, "Transition metal complexes of oxazolinylboranes and cyclopentadienyl-bis(oxazolinyl)borates: Catalysts for asymmetric olefin yh droamination and acceptorless alcohol decarbonylation" (2012). Graduate Theses and Dissertations. 12861. https://lib.dr.iastate.edu/etd/12861 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Transition metal complexes of oxazolinylboranes and cyclopentadienyl- bis(oxazolinyl)borates: Catalysts for asymmetric olefin hydroamination and acceptorless alcohol decarbonylation by Kuntal Manna A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Inorganic Chemistry Program of Study Committee: Aaron D. Sadow, Major Professor Marek Pruski Andreja Bakac Javier Vela Malika Jeffries-EL Iowa State University Ames, Iowa 2012 Copyright © Kuntal Manna, 2012. All rights reserved. ii Dedicated to my Family iii Table of Contents Acknowledgements v Abstract viii Chapter 1 – Introduction 1 General Introduction 1 Thesis Organization 8 References 9 Chapter 2 - Neutral cyclopentadienyl-bis(oxazolinyl)borato group 4 complexes as catalysts for enantioselective hydroamination of aminoolefins 12 Abstract 12 Introductions 13 Results and Discussion 17 Conclusions 66 Experimental 67 References 103 Chapter 3 - The desymmetrization of non-conjugated aminodienes and aminodiynes through enantioselective and diastereoselective hydroamination 110 Abstract 110 Introduction 111 Results and Discussion 112 Conclusions 125 Experimental 126 References 136 iv Chapter 4 - Concerted C–N and C–H bond formation in highly enantioselective yttrium(III)-catalyzed hydroamination: Comparison of stereoinduction with zirconium analogs 139 Abstract 139 Introduction 140 Results and Discussion 144 Conclusions 172 Experimental 173 References 191 Chapter 5 - Acceptorless thermal decarbonylation of alcohols catalyzed by oxazolinylborato iridium complexes 195 Abstract 195 Introduction 196 Results and Discussion 198 Conclusions 218 Experimental 219 References 231 Chapter 6 – Conclusion 235 Vita 238 v Acknowledgements First and foremost, I am heartily thankful to my advisor Prof. Aaron D. Sadow, without whom this thesis would not have been possible. I am indebted to him for taking me into his group and teaching me how to appreciate science, to make molecules, and to have a vision for the future. Not only has he been an excellent teacher and mentor, but also his undaunted enthusiasm, suggestions, encouragements, and moral support inspired me to do more experiment in laboratory, and also helped to satisfy myself for my successful graduate research. I am very fortunate having an excellent advisor for my Ph.D. study. I have promised myself that I would try to be a mentor like Prof. Sadow in my future independent career. I express my gratitude to all of my POS committee members- Prof. Andreja Bakac, Prof. Marek Pruski, Prof. Javier Vela, and Prof. Malika Jeffries-EL for their valuable support, advice, and input in my research. Thanks to all of my past and present labmates in Sadow group: Ben Baird, Dr. James Dunne, Dr. Steven Neal, Dr. Hung-An Ho, KaKing Yan, Dr. Andrew Pawlikowski, Jiachun Su, Songchen Xu, Naresh Eedugurala, Zak Weinstein, Megan Hovey, Nicole Lampland, Aradhana Pindwal, Jacob Fleckenstein, Regina Reinig, Jing Zhu, Bradley Schmidt, Jiachun Su, Dr. Barun Jana, Stephanie Smith, and Debabrata Mukherjee for their cooperation, support and fun in last five years. Especially, I am grateful to Steven, Isaac, Kaking, James, and Andy who provided me a countless valuable suggestions and help since my first day in Sadow group. Thanks to Dr. Ho again for teaching me several introductory level courses such as golfing, snowboarding etc. I thank Marissa L. Kruse and Jessica Brown, who had conducted excellent research with me in Sadow lab. I also like to thank all other undergraduates who have worked in our lab over the years: Yitzhak, Brianna, Marlie, Tristan, Jared, Kate, Jooyoung, Rick, and Josh. vi I gratefully thank all the members of CBS catalysis program in Ames laboratory. I enjoyed working as part of this great collaborative research project, and became knowledgeable with many other fields in chemistry outside of my research area. I like to thank Dr. Takeshi Kobayashi for the solid state NMR experiments of my samples. Thanks to Prof. Victor Shang-Yi Lin, Dr. Igor I. Slowing, Dr. Brian Trewyn, and their group members for our collaboration and also allowing me to access instruments within their laboratory. I also thank Prof. Marek Pruski and Prof. Jason Chen for our collaboration. I like to thank Prof. Aaron D. Sadow, Prof. Andreja Bakac, and Prof. Arthur Winter for their invaluable lectures in CHEM courses. I thank all staffs in chemical instrument services, glass shop, and machine shop in our department. Thanks to Dr. Shu Xu, Dr. Sarah Cady, Dr. Dave Scott, and Dr. Bruce Fulton for helping me several NMR experiments in my research. Thanks to Prof. Malika Jeffries-EL for letting me use the HPLC in her laboratory. I would like to acknowledge support of all the members from Department of Chemistry, Iowa State University. I owe my deepest gratitude to all professors and laboratory stuffs in Panskura Banamali College and Indian Institute of Technology, Kanpur (IIT Kanpur) for teaching me chemistry. I gratefully thank Prof. V. Chandrasekhar at IIT Kanpur, whose guidance and encouragement influenced me significantly to be a motivated student during my graduate studies. I also express my gratitude to Prof. Mahadev Maity, Prof. Tridip Tripathy, and Prof. S. Pahari for their guidance and excellent teaching of undergraduate chemistry. A very large thank you to my friends Saptak, Haradhan, Sujoy, Rajada, Akshay, Labakanta, Khitish, Subhas, Ajit, Amit, Parimalda, Biplabda, and Subratada. I can never forget their support and fun times we had together during my undergraduate and graduate studies. I also like to thank Pranaw Kunal, Premkumar, Raghu V Maligal Ganesh, Songchen Xu, Naresh vii Eedugurala, Zak Weinstein, Ananitra Ghosh, Ramkrishna Adhikary, Prasun Mukherjee, Supratim Giri, Sayantan Bose, and Shibabrata Nandi for their help in Ames. I am indebted to my patents for their love, constant support, encouragement, and sacrifices. I am grateful to my brother for his love and full support. I also thank all other family members with all my heart for their love. I thereby dedicate this thesis to my family. Finally, I like to acknowledge the Ames Laboratory, the Henry Gilman Fellowship, and Iowa State University for funding and support of my research. viii Abstract The research presented and discussed in this dissertation involves the synthesis of transition metal complexes of oxazolinylboranes and cyclopentadienyl-bis(oxazolinyl)borates, and their application in catalytic enantioselective olefin hydroamination and acceptorless alcohol decarbonylation. Neutral oxazolinylboranes are excellent synthetic intermediates for preparing new borate ligands and also developing organometallic complexes. Achiral and optically active bis(oxazolinyl)phenylboranes are synthesized by reaction of 2-lithio-2-oxazolide and 0.50 equiv of dichlorophenylborane. These bis(oxazolinyl)phenylboranes are oligomeric species in solid state resulting from the coordination of an oxazoline to the boron center of another borane monomer. The treatment of chiral bis(oxazolinyl)phenylboranes with sodium cyclopentadienide R R provide optically active cyclopentadienyl-bis(oxazolinyl)borates H[PhB(C 5H5)(Ox )2] [Ox = Ox 4S-iPr,Me2 , Ox 4R-iPr,Me2 , Ox 4S-tBu ]. These optically active proligands react with an equivalent of M(NMe 2)4 (M = Ti, Zr, Hf) to afford corresponding cyclopentadienyl-bis(oxazolinyl)borato R group 4 complexes {PhB(C 5H4)(Ox )2}M(NMe 2)2 in high yields. These group 4 compounds catalyze cyclization of aminoalkenes at room temperature or below, providing pyrrolidine, piperidine, and azepane with enantiomeric excesses up to 99%. Our mechanistic investigations suggest a non-insertive mechanism involving concerted C−N/C−H bond formation in the turn- over limiting step of the catalytic cycle. Among cyclopentadienyl-bis(oxazolinyl)borato group 4 catalysts, the zirconium complex 4S-iPr,Me2 {PhB(C 5H4)(Ox )2}Zr(NMe 2)2 ({S-2}Zr(NMe 2)2) displays highest activity and enantioselectivity. Interestingly, {S-2}Zr(NMe 2)2 also desymmetrizes olefin moieties of achiral ix non-conjugated aminodienes and aminodiynes during cyclization. The cyclization of aminodienes catalyzed by {S-2}Zr(NMe 2)2 affords diastereomeric mixture of cis and trans cylic amines with high diasteromeric ratios and excellent enantiomeric excesses. Similarly, the desymmetrization of alkyne moieties in { S-2}Zr(NMe 2)2-catalyzed cyclization of aminodiynes provides corresponding cyclic
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