WWW.DISSERTATION.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Dissertations, online materials
 
<< HOME
CONTACTS



Pages:   || 2 | 3 | 4 | 5 |   ...   | 32 |

«Date:_ Approved: _ Ross A. Widenhoefer, Supervisor _ Katherine J. Franz _ Jiyong Hong _ Qiu Wang Dissertation submitted in partial fulfillment of the ...»

-- [ Page 1 ] --

Model Studies of Proposed Intermediates in Homogeneous Gold(I) Catalysis

by

Timothy Justin Brown

Department of Chemistry

Duke University

Date:_______________________

Approved:

___________________________

Ross A. Widenhoefer, Supervisor

___________________________

Katherine J. Franz

___________________________

Jiyong Hong

___________________________

Qiu Wang

Dissertation submitted in partial fulfillment of

the requirements for the degree of Doctor of Philosophy in the Department of Chemistry in the Graduate School of Duke University i v ABSTRACT Model Studies of Proposed Intermediates in Homogeneous Gold(I) Catalysis by Timothy Justin Brown Department of Chemistry Duke University Date:_______________________

Approved:

___________________________

Ross A. Widenhoefer, Supervisor ___________________________

Katherine J. Franz ___________________________

Jiyong Hong ___________________________

Qiu Wang An

Abstract

of a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry in the Graduate School of Duke University Copyright by Timothy Justin Brown Abstract The ability of gold(I) complexes to function as catalysts for myriad organic transformations has led to a dramatic increase in their utilization. Among the homogeneous reactions catalyzed by gold(I), carbon–carbon and carbon–heteroatom bond forming processes are of particular interest for the fields of organic synthesis and pharmaceutical development. Discussed herein are gold(I)-catalyzed methods for the intra- and intermolecular functionalization of alkenes, alkynes, and allenes with nitrogenand oxygen-based nucleophiles leading to new C‒X bonds (X = N, O).

Approximately 26 cationic gold π-alkene complexes, containing either IPr [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] or P(t-Bu)2o-biphenyl ancillary ligands, were isolated or generated and six complexes were analyzed by X-ray crystallography. Spectroscopy, X-ray crystallography, and alkene binding studies are in accord with a gold−(π-alkene) interaction dominated by σ-donation from the alkene to gold. Kinetic analyses of degenerate isobutylene exchange in both the IPr and phosphine systems are consistent with associative pathways for isobutylene exchange involving cationic bis(alkene) intermediates.

Reaction of a 1:1 mixture of (L)AuCl [L = P(t-Bu)2o-biphenyl or IPr] and AgSbF6 with internal alkynes led to isolation of the corresponding cationic, two-coordinate gold -alkyne complexes in ≥90% yield. Equilibrium binding studies show that the binding affinities of alkynes to gold(I) are strongly affected by the electron density of the alkyne and to a lesser extent on the steric bulk of the alkyne. Treatment of a suspension of

–  –  –

unstable gold π-alkyne complexes of the form [(IPr)Au(2-HC≡CAr)]+ SbF6– in ≥86 ± 5% yield, which were characterized by spectroscopy without isolation. Warming these complexes to 0 °C led to C(sp)–H bond cleavage and formation of dinuclear gold(I) σ,πacetylide complexes of the form {[(IPr)Au]2(1,2-C≡CAr)}+ SbF6–, three of which were isolated in 99% yield and one of which was characterized by X-ray crystallography.

A family of 7 cationic gold(I) -allene complexes were isolated and fully characterized in solution, and in three cases by X-ray crystallography. Degenerate intermolecular allene exchange kinetic studies for three of the allene complexes are in accord with a two-term rate law of the form rate = k1[complex] + k2[complex][allene] with energy barriers of G‡1 = 17.4 – 18.8 kcal mol-1 and G‡2 = 15.2 – 17.6 kcal mol-1.

Variable temperature NMR analysis of these complexes established facile intramolecular -face exchange through 1-allene intermediates or transition states with barriers of G‡ = 8.9 – 10.9 kcal mol-1 for phosphine and 9.5 – 12.2 kcal mol-1 for IPr complexes.

–  –  –

hydroalkoxylation established a mechanism involving rapid and reversible C–O bond formation followed by turnover-limiting protodeauration from a mono(gold) vinyl complex. This on-cycle pathway competes with catalyst aggregation and formation of an off-cycle bis(gold) vinyl complex.

–  –  –

Abstract

List of Tables

List of Figures

Acknowledgements

Chapter 1

Carbophilic Gold(I) and Its Niche in Homogeneous Transition-Metal Catalysis.............. 1

1.1 Introduction

1.1.1 Significance of Transition Metal Catalysis

1.1.2 Background on Cationic Gold(I)

1.1.2.1 Significance

1.1.2.2 Bonding Modes in Gold(I) -Complexes

1.1.2.3 Two-Coordinate Geometry

1.1.2.4 Relativistic Effects in Gold Catalysis

1.2 Organic Reactions of Alkenes, Alkynes, and Allenes Catalyzed by Gold(I)........ 9 1.2.1 Reactions of Alkenes

1.2.1.1 C–N Bond-Forming Reactions

1.2.1.2 C–O Bond-Forming Reactions

1.2.2 Reactions of Alkynes

1.2.2.1 C–N Bond-Forming Reactions

1.2.2.2 C–O Bond-Forming Reactions

1.2.3 Reactions of Allenes





–  –  –

1.2.3.2 C–O Bond-Forming Reactions

1.3 Conclusions

Chapter 2

Cationic, Two-Coordinate Gold(I) -Alkene Complexes: Synthesis and Solution Behavior

2.1 Introduction

2.1.1 Background

2.1.1.1 Neutral Two-Coordinate Gold(I) Complexes

2.1.1.2 Neutral Three-Coordinate Gold(I) Complexes

2.1.1.3 Cationic Three-Coordinate Gold(I) Complexes

2.1.1.4 Cationic, Two-Coordinate Gold(I) Complexes

2.1.2 Project Goals and Scope

2.2 Results and Discussion

2.2.1 Monomeric, Cationic, Two-Coordinate Gold(I) -Alkene Complexes that Contain an N-Heterocyclic Carbene Ligand

2.2.1.1 Introduction

2.2.1.2 Synthesis and Characterization

2.2.1.3 Relative Binding Affinities of Alkenes

2.2.1.4 Degenerate Isobutylene Exchange

2.2.1.5 Summary

2.2.2 Monomeric, Cationic, Two-Coordinate Gold(I) -Alkene Complexes that Contain a Sterically-Hindered o-Biphenylphosphine Ligand

2.2.2.1 Synthesis and Characterization

–  –  –

2.2.2.3 Degenerate Isobutylene Exchange

2.2.2.4 Summary

2.3 Experimental Section

2.3.1 General Methods

2.3.2 Synthesis of N-Heterocyclic Carbene Gold(I) Complexes

2.3.2.1 Synthesis of N-Heterocyclic Carbene Gold(I) -Alkene Complexes...... 72 2.3.2.2 In situ characterization Gold(I) -Alkene Complexes

2.3.2.3 Determination of Alkene Binding Constants

2.3.2.4 Kinetics of Isobutylene Exchange with 18

2.3.2.5 X-ray Crystal Structure Data for N-Heterocyclic Carbene Gold(I) Alkene Complexes 18•2CH2Cl2, 19, and 20•2CH2Cl2

2.3.3 Synthesis of P(t-Bu)2o-biphenyl Gold(I) Complexes

2.3.3.1 Synthesis of P(t-Bu)2o-biphenyl Gold(I) -Alkene Complexes.............. 88 2.3.3.2 In Situ Characterization of Gold(I) -Alkene Complexes

2.3.3.3 Determination of Alkene Binding Constants

2.3.3.4 Kinetics of Isobutylene Exchange with 33

2.3.3.5 X-ray Crystal Structure Data for Phosphine Gold(I) -Alkene Complexes 31, 35•CH2Cl2, and 38

Chapter 3

Cationic Gold(I) -Alkyne Complexes and the Conversion of Terminal Alkyne Complexes to Dinuclear -Acetylide Complexes

3.1 Introduction

3.1.1 Neutral and Cationic Gold(I) -Alkyne Complexes

–  –  –

3.1.3 Terminal Alkyne -Complex → -Complex Conversion

3.2 Results and Discussion

3.2.1 Cationic, Two-Coordinate Gold(I) -(Internal Alkyne) Complexes............ 112 3.2.1.1 Synthesis of Gold -Alkyne Complexes

3.2.1.2 Determination of Alkyne Binding Constants

3.2.1.3 Summary

3.2.2 Cationic, Two-Coordinate Gold(I) -(Terminal Alkyne) Complexes and Their Conversion to Dinuclear Gold(I) -Acetylide Complexes

3.2.2.1 Synthesis of Gold -Complexes of Terminal Alkynes

3.2.2.2 Binding Affinity of Arylacetylenes to (IPr)Au+

3.2.2.3 Formation and Stability of Dinuclear Gold -Acetylide Complexes. 122 3.2.2.4 Arylacetylene Protonation in Dinuclear -Acetylide Formation....... 129 3.2.2.5 Kinetic Analysis of -Acetylide Formation

3.2.2.6 Mechanistic Discussion

3.2.2.7 Summary

3.3 Experimental

3.3.1 General Methods

3.3.2 Gold(I) -(Internal Alkyne) Complexes

3.3.2.1 Synthesis of Gold(I) -Alkyne Complexes

3.3.2.2 Determination of Alkyne Binding Constants

3.3.3 Gold(I) -(Terminal Alkyne) Complexes

3.3.3.1 Synthesis of Gold(I) -Arylacetylene Complexes

–  –  –

3.3.3.3 Synthesis of Digold -Acetylide Complexes

3.3.3.4 X-ray Crystal Structure of 36•3CH2Cl2

3.3.3.5 Independent Synthesis of 41 and 42

3.3.3.6 Binding Affinity and Protonation Stability Studies of 36 and 41.......... 157 3.3.3.7 Experiments Probing Protonation of Free Arylacetylene in the Conversion of -Arylacetylene Complexes to Dinuclear -Acetylide Complexes............ 159 3.3.3.8 Kinetic Analysis of the Conversion of -Arylacetylene Complex 32 to Dinuclear -Acetylide Complex 37

Chapter 4

Cationic, Two-Coordinate Gold(I) -Allene Complexes: Structures and Dynamic Solution Behavior

4.1 Introduction

4.2 Results and Discussion

4.2.1 Synthesis of Gold(I) -Allene Complexes

4.2.2 Relative Binding Affinities of Allenes to Gold(I)

4.2.3 Solid State Structures of Complexes 14, 18, and 19

4.2.4 Solution Structure and Fluxional Behavior of Gold(I) -Allene Complexes 194 4.2.4.1 Solution Structure and Fluxional Behavior of Complexes 14 – 17....... 194 4.2.4.2 Solution Structure and Fluxional Behavior of Complexes 18 and 19... 202 4.2.4.3 Solution Structure and Fluxional Behavior of Complex 20

4.2.5 Kinetics of Intermolecular Allene Exchange

4.2.6 Gold(I)-Mediated Tetramethylallene Tautomerization

4.2.7 Summary

–  –  –

4.3.1 General Methods

4.3.2 Synthesis of Gold(I) -Allene Complexes

4.3.3 Determination of Allene Binding Constants

4.3.4 Kinetics of Intramolecular -Face Exchange

4.3.5 Kinetics of Intermolecular Allene Exchange

4.3.6 Experiments Probing Tetramethylallene Tautomerization

4.3.7 X-ray Crystal Structure Determinations

Chapter 5

Gold(I)-Catalyzed Intramolecular Hydroalkoxylation of Allenes: Kinetics and Mechanism

5.1 Introduction

5.2 Results and Discussion

5.2.1 Synthesis of Gold Vinyl Intermediates

5.2.2 Catalytic Relevance of Mono(gold) and Bis(gold) Complexes

5.2.3 Kinetic Analysis of the Catalytic Conversion of 14 to 15

5.2.4 Protodeauration of Vinyl Gold Complexes 16 and 17

5.2.4.1 Protonation of Mono(gold) Vinyl 16 with Various Acids

5.2.4.2 Kinetic Analysis of Mono(gold) 16 Protonation with Acetic Acid....... 261 5.2.4.3 Kinetic Analysis of Bis(gold) 17 Protonation with Tosylic Acid.......... 263 5.2.5 Equilibrium Binding Constants

5.2.6 Mechanistic Discussion

5.2.7 Stereochemistry of C‒O Bond Formation

–  –  –

5.3 Experimental

5.3.1 General Methods

5.3.2 Syntheses

5.3.3 Kinetics Analysis of the Catalytic Conversion of 14 to 15

5.3.4 Protonolysis Experiments

5.3.4.1 Kinetic Analysis of the Stoichiometric reaction of 16 with HOAc/DOAc.

5.3.4.2 Kinetic Analysis of the Stoichiometric reactions of 17 with HOTs/DOTs.

5.3.5 Stoichiometric and Catalytic Reactions of 14 with (L)AuOTs

5.3.6 Analysis of Bis(gold) 17 and 17-d2 Under Catalytic Conditions.................. 296 5.3.7 X-ray Crystal Structures of Mono(gold) Vinyl Complexes 16 and 19......... 301 Appendix

Platinum(II)–Alkyl Bond Protonolysis in the Intramolecular Hydroamination of Olefins with Secondary Alkylamines

A.1 Introduction

A.2 Results and Discussion

A.3 Experimental

A.3.1 General Methods

A.3.2 Synthesis of Platinacyclobutane

A.3.3 Mechanistic and Kinetic Experiments

References

Biography

–  –  –

Table 1. 1H and 13C NMR data for the olefinic resonances of cationic gold -alkene complexes.

Free alkene resonances are shown in parenthesis for comparison................ 51 Table 2. 1H and 13C NMR data for the olefinic resonance of in situ generated cationic gold -alkene complexes.

Resonances corresponding to free alkene are shown in parentheses for comparison

Table 3. Equilibrium constants for reaction of alkenes and vinyl arenes with 16 in CD2Cl2 at ‒60 °C.

Table 4. Observed rate constants for the exchange of the isobutylene ligand of 18 ([18] = 40 mM) with free isobutylene at 25, 45, and 63 °C.

Table 5. 1H and 13C NMR data for olefinic resonances of isolated and in situ generated gold -alkene complexes.

Resonances corresponding to free alkene are shown in parentheses for comparison

Table 6. Equilibrium constants for reaction of aliphatic alkenes and vinyl arenes with 44 in CD2Cl2 at ‒60 °C.

Table 7. Observed rate constants for the exchange of the isobutylene ligand of 33 ([33] = 40 mM) with free isobutylene at 11, 25, and 40 °C.

Table 8. Line broadening data and observed rate constants (kobs) for the exchange of the isobutylene ligand of 18 ([18] = 40 mM) with free isobutylene.

Table 9. Second-order rate constants (kex) for the exchange of the isobutylene ligand of 18 with free isobutylene at 25, 45, and 63 °C.



Pages:   || 2 | 3 | 4 | 5 |   ...   | 32 |


Similar works:

«CONDITION MONITORING OF ELECTROLYTIC CAPACITORS FOR POWER ELECTRONICS APPLICATIONS A Dissertation Presented to The Academic Faculty by Afroz M. Imam In Partial Fulfillment Of the Requirements for the Degree Doctor of Philosophy in the School of Electrical and Computer Engineering Georgia Institute of Technology May, 2007 CONDITION MONITORING OF ELECTROLYTIC CAPACITORS FOR POWER ELECTRONICS APPLICATIONS Approved by: Prof. Ronald G. Harley, Advisor Prof. Deepak M. Divan, Co-advisor School of...»

«STUDY OF RADIATIVE PROPERTIES OF THIN FILMS AND NEAR-FIELD RADIATION FOR THERMOPHOTOVOLTAIC APPLICATIONS A Dissertation Presented to The Academic Faculty by Jesse I. Watjen In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology May 2016 Copyright © Jesse I Watjen 2016 STUDY OF RADIATIVE PROPERTIES OF THIN FILMS AND NEAR-FIELD RADIATION FOR THERMOPHOTOVOLTAIC APPLICATIONS Approved...»

«1 Naturalizing the Human or Humanizing Nature: Science, Nature and the Supernatural1 Dr. David Macarthur Lecturer in Philosophy, University of Sydney, Australia The Department of Philosophy Main Quad, A14 The University of Sydney N.S.W. 2006, Australia Tel: +61-2-9351-3193 Mobile: 0404-861-162 Fax: +61-2-9351-6660 2 Abstract The present paper challenges the narrow scientistic conception of Nature that underlies current projects of ‘naturalization’ involving, say, evaluative or intentional...»

«BA RU C H S. B L U M B E R G FRANK MARGESON 28 july 1925. 5 april 2011 PROCEEDINGS OF THE AMERICAN PHILOSOPHICAL SOCIETY VOL. 155, NO. 3, SEPTEMBER 2011 biographical memoirs B ARUCH S. BLUMBERG (Barry) was a very active and enthusiastic member of the Society from his election on 25 April 1986 until his death on 5 April 2011. He presented papers: “Hepatitis B Virus and the Prevention of Primary Cancer of the Liver” (November 1980) and “Humboldt in Philadelphia” (April 1989), and...»

«INNOVATION-DIFFUSION PROCESSES IN URBAN DESIGN MOVEMENTS: APPLICATION OF THE MODEL-PROTOTYPE-ADAPTATION FRAMEWORK TO NEW URBANISM AND NEIGHBORHOOD DEVELOPMENT PRACTICES IN ATLANTA A Dissertation Presented to The Academic Faculty By Jaecheol Kim In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in Architecture Georgia Institute of Technology December 2010 COPYRIGHT 2010 BY JAECHEOL KIM INNOVATION-DIFFUSION PROCESSES IN URBAN DESIGN MOVEMENTS: APPLICATION OF THE...»

«ABSTRACT Title of dissertation: HOW L2 LEGAL WRITERS USE STRATEGIES FOR SCHOLARLY WRITING: A MIXED METHODS STUDY Donna Bain Butler, Doctor of Philosophy, 2010 Dissertation directed by: Professor Rebecca L. Oxford Department of Curriculum and Instruction Second Language Education and Culture This dissertation research fills existing gaps regarding the practices and processes of teaching second language (L2) writers at higher ranges of proficiency in law school context. It is a mixed methods,...»

«PEER VICTIMIZATION, PHYSICAL ACTIVITY, AND SOCIAL-PSYCHOLOGICAL ADJUSTMENT IN OBESE YOUTH By CHARISSE WILLIAMS A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2007 1 © 2007 Charisse Williams 2 To my best friend, Jocelyn Lee 3 ACKNOWLEDGMENTS I would like to thank Jocelyn Lee for her assistance and constant support through this difficult process. I would to thank...»

«Bibliography of Literature on the Mimetic Theory vol. XXIX by Dietmar Regensburger, University of Innsbruck published in: COV&R: Bulletin of the Colloquium on Violence & Religion vol. 35 (October 2009) 1) Books concerning the entire work of René Girard For René Girard: Essays in Friendship and in Truth, edited by Sandor Goodhart, Tom Ryba, Jørgen Jørgensen, and James Williams. Studies in Violence, Mimesis, and Culture 2. East Lansing, MI/USA: Michigan State University Press, 2009. (single...»

«A TYPOLOGY OF SAMPLING IN HIP-HOP Amanda Sewell Submitted to the faculty of the University Graduate School in partial fulfillment of the requirements for the degree Doctor of Philosophy in the Musicology Department of the Jacobs School of Music Indiana University May 2013 Accepted by the Graduate Faculty, Indiana University, in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Doctoral Committee _ J. Peter Burkholder, Ph.D. _ Phil Ford, Ph.D. _ Daniel R. Melamed,...»

«The New Zealand Dressmaker: Experiences, Practices and Contribution to Fashionability, 1940 to 1980. A thesis submitted in (partial) fulfilment of the requirements for the degree of Doctor of Philosophy Jan Hamon MA (Fashion & Textile Studies) School of Design and Architecture RMIT University July 2007 i Declaration I certify that except where due acknowledgement has been made, the work is that of the author alone; the work has not been submitted previously, in whole or in part, to qualify for...»

«Lamenting Loss: Public and Private Grief in the Elegies of Poe, Dickinson, Alcott, and Crane by Joy Smith A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in English Middle Tennessee State University Dissertation Committee: Dr. Philip Phillips, Chair Dr. Alicia Mischa Renfroe Dr. Patricia Gaitely I dedicate this research to my grandfather, James William “J.W.” Moss, Sr. I love you and will miss you daily until I see you in Heaven,...»

«  Thinking about Citizen Journalism   |   Lewis, Kaufhold, & Lasorsa, 2009  Thinking about Citizen Journalism: Perspectives on Participatory News Production at Community Newspapers By Seth C. Lewis, Kelly Kaufhold, and Dominic L. Lasorsa Paper presented at the International Symposium on Online Journalism Austin, Texas • April 18, 2009 Abstract This study seeks to understand how community newspaper editors negotiate the professional challenges posed by citizen journalism—a...»





 
<<  HOME   |    CONTACTS
2016 www.dissertation.xlibx.info - Dissertations, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.