University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 8-2012 Select Reactions of Organoboranes and Organostannanes David W. Blevins [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Organic Chemistry Commons Recommended Citation Blevins, David W., "Select Reactions of Organoboranes and Organostannanes. " PhD diss., University of Tennessee, 2012. https://trace.tennessee.edu/utk_graddiss/1412 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by David W. Blevins entitled "Select Reactions of Organoboranes and Organostannanes." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Chemistry. George W. Kabalka, Major Professor We have read this dissertation and recommend its acceptance: Shane Foister, Craig Barnes, Kimberly Gwinn Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Select Reactions of Organoboranes and Organostannanes A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville David W. Blevins August 2012 DEDICATION I dedicate this work to Lisa, Preston, and Clarissa Blevins. ii ACKNOWLEDGEMENTS I would like to thank Dr. George Kabalka for giving me the opportunity to do research in the Boron group, and for providing me with financial support. Thanks to Dr. Min-Liang Yao for your help and advice in my research. Also, I would like to acknowledge Dr. Michael Quinn, Vitale Coltuclu, and Dr. Li Yong for kindly offering their assistance whenever I needed it. To my wife and children, Lisa, Clarissa, and Preston, thank you all for your support and encouragement. You all are such a blessing in my life. Also, I would like to thank Ronald and Judy Hensley for their friendship, support, and prayers during the last two years, and most of all I would like to thank God for my loving family. iii ABSTRACT Potassium aryl- and alkenyltrifluoroborates and tributyl(aryl)stannanes were found to undergo halodemetallation using trihalide salts, Y(X3), where X=Br or I; Y=Cs or pyridinium. The hydrolysis of organotrifluoroborates was observed to be promoted by iron(III) chloride, zinc dust, and zinc oxide. A variety of potassium aryltrifluoroborates and an alkenyltrifluoroborate were found to undergo bromodeboronation at room temperature in a (1:1) THF/water solution in 30-40 minutes using pyridinium tribromide, providing good yields of aryl and vinyl bromides. Activated arenes underwent dibromination, but this was reduced by adding potassium bromide to the reaction. Potassium aryltrifluoroborates and an alkenyltrifluoroborate were observed to undergo iododeboronation in a (1:2) DMF/water solution at 80 degrees Celsius using cesium triiodide. Activated aryl substrates provide the highest yields of the aryl iodide products. Aryltrifluoroborates with electron withdrawing substituents provided low product yields. Potassium pyridinyl-4-trifluoroborate did not undergo iododeboronation. Unsubstituted aryltrifluoroborates provided modest product yields. A route to (Z)-1,2-dibromoalkenes via the bromodeboronation of stereo- defined potassium alkenylditrifluoroborates using tetrabutylammonium tribromide was investigated. The reaction was found to produce good product yields with very high (Z) stereoselectivity from functionally unsubstituted potassium alkenylditrifluoroborates, but functionalized alkenylditrifluoroborates could not be obtained due to the lack of reactivity of the functionalized alkyne precursors in the diborylation reaction required for their synthesis. Iron(III) chloride, zinc dust, and zinc oxide were found to promote the efficient hydrolysis of potassium organotrifuoroborates in a (1:1) THF/water solution. Excellent yields of the corresponding alkyl-, aryl-, and alkenylboronic acids were obtained in most cases. The hydrolysis reactions are thought to occur due the formation of insoluble fluoride salts. iv Iron(III) chloride/sodium iodide was found to be an effective combination to carry out iododeboronation reactions of potassium aryl- and alkenyltrifluoroborates in dry acetonitrile at 80 degrees Celsius in about 19 hours. Good yields of the corresponding iodide products were obtained in most trials. Iron(III) chloride/sodium iodide was also found to be an effective combination to carry out iododestannation reactions of a variety of tributyl(aryl)stannanes at room temperature in a (1:1) THF/water solution. The reactions generally require 40-60 minutes providing excellent yields of the aryl iodide products in most cases. v TABLE OF CONTENTS Chapter I Signifigance of Aryl halides and Vinyl Halides in Organic Chemistry 1.1 Aryl Halides and Vinyl Halides in the Formation of Organomagnesium and Organolithium Reagents……………………………………………………………1 1.2 Organometallic Reagents Derived from Organomagnesium and Organolithium Reagents and Their Reactions…………………………………...3 1.3 Palladium Catalyzed Coupling Reactions That Utilize Aryl and Vinyl Halides……………………………………………………………………………...10 1.4 Methods for Synthesizing Aryl Halides………………………………………….12 1.5 Methods for Synthesizing Vinyl Halides………………………………………...16 1.6 Halodemetallations of Aryl and Vinylboranes…………………………………..20 1.7 Recent Advances by the Kabalka Group in the Halodemetallation Reactions of Organoboranes…………………………………………………………………25 1.8 The Hydrolysis of Potassium Organotrifluoroborates…………………………30 Chapter 2 Bromodeboronation of Potassium Aryl- and Alkenyltrifluoroborates Using Pyridinium Tribromide 2.1 Introduction………………………………………………………………………...36 2.2 Results and Discussion…………………………………………………………..36 2.3 Conclusions………………………………………………………………………..40 2.4 Experimental……………………………………………………………………….40 2.5 Typical Procedue for Bromodeboronation Reaction…………………………..41 2.6 Characterization of Compounds…………………………………………………41 Chapter 3 Iododeboronation of Potassium Aryl- and Alkenyltrifluoroborates Using Cesium Triiodide 3.1 Introduction………………………………………………………………………...52 vi 3.2 Results and Discussion……………………………………………………….….52 3.3 Conclusions………………………………………………………………………..57 3.4 Experimental……………………………………………………………………….57 3.5 Typical Procedure for Iododeboronation Reactions…………………………...58 3.6 Characterization of Compounds…………………………………………………58 Chapter 4 The Synthesis of (Z)-1,2-Dibromoalkenes from Stereo-defined Potassium Alkenylditrifluoroborates 4.1 Introduction………………………………………………………………………...60 4.2 Results and Discussion…………………………………………………………..60 4.3 Conclusions………………………………………………………………………..64 4.4 Experimental……………………………………………………………………….64 4.5 General Procedure for the Synthesis of (Z)-1,2-Dibromoalkenes……………65 4.6 Characterization of Compounds…………………………………………………66 Chapter 5 Iron(III) Chloride Promoted Hydrolysis of Potassium Organotrifuoroborates 5.1 Introduction………………………………………………………………………...69 5.2 Results and Discussion…………………………………………………………..69 5.3 Other Investigations………………………………………………………………75 5.4 Conclusions………………………………………………………………………..80 5.5 Experimental……………………………………………………………………….81 5.6 Typical Procedure…………………………………………………………………81 5.7 Characterization of Compounds…………………………………………………82 vii Chapter 6 Iododebronation of Potassium Aryl- and Alkenyltrifluoroborates with Iron(III) Chloride and Sodium Iodide 6.1 Introduction………………………………………………………………………...90 6.2 Results and Discussion…………………………………………………………..90 6.3 Conclusions………………………………………………………………………..94 6.4 Experimental……………………………………………………………………….94 6.5 Typical Procedure…………………………………………………………………94 6.6 Characterization of Compounds…………………………………………………95 Chapter 7 Iododeboronation of Tributyl(aryl)stannanes 7.1 Introduction………………………………………………………………………...98 7.2 Results and Discussion…………………………………………………………..98 7.3 Conclusions………………………………………………………………………100 7.4 Experimental……………………………………………………………………..101 7.5 Typical Procedure………………………………………………………………..101 7.6 Characterization of Compounds………………………………………………..102 List of References............................................................................................104 Appendix……………………………………………………………………………..122 Vita…………………………………………………………………………………….253 viii LIST OF TABLES Table 1.1 Selectivity of Organotitanium Reagents in 1,2-Additions….……………5 Table A-1 Crystal data and structure refinement for (Z)- dibromodiphenylalkene………………………………………………………………174 Table A-2 Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for Yml-2012. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor………………………………………………………..175 Table A-3 Bond lengths [Å] and angles [°] for Yml-2012……………………....176-178 Table A-4 Anisotropic displacement parameters (Å2x 103) for Yml-2012. The anisotropic displacement factor exponent takes the form: -2 2[ h2 a*2U11 + ... + 2 h k a* b* U12 ]..............................................................................................179 Table A-5 Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for Yml-2012……………………………………………………………..180 Table A-6 Torsion angles