Amines in Olefin Metathesis: Ligands and Poisons Benjamin John Ireland A thesis submitted to the Faculty of Graduate and Postdoctoral Studies in partial fulfillment of the requirements for the degree of Doctor of Philosophy Ottawa-Carleton Chemistry Institute Faculty of Science University of Ottawa © Benjamin J. Ireland, Ottawa, Canada 2016 Table of Contents Abstract ............................................................................................................................................... IV Acknowledgements .............................................................................................................................. V Lists of Compounds and Abbreviations ........................................................................................... VI Lists of Charts, Schemes, Figures, and Tables .............................................................................. XIV Chapter 1. Introduction ......................................................................................................................... 1 1.1. Catalysis ...................................................................................................................................... 1 1.2. Olefin metathesis ......................................................................................................................... 2 1.2.1. A powerful tool for organic synthesis .................................................................................. 2 1.2.2. The history and mechanism of olefin metathesis - highlights .............................................. 5 1.2.3. Well-defined metal alkylidenes as metathesis catalysts ....................................................... 7 1.2.4. Non-productive metathesis reactions ................................................................................. 11 1.3. Catalyst decomposition pathways ............................................................................................. 13 1.3.1. Inherent decomposition of Ru-alkylidenes and MCB complexes ....................................... 13 1.3.2. Decomposition induced by chemical additives .................................................................. 14 1.4. Amines in catalyst design - opportunities .................................................................................. 17 1.5. Scope of thesis ........................................................................................................................... 18 Chapter 2. Experimental Details ......................................................................................................... 23 2.1. General procedures ................................................................................................................... 23 2.1.1. Reaction conditions ............................................................................................................ 23 2.1.2. Reagents and solvents ........................................................................................................ 23 2.1.3. Instrumentation .................................................................................................................. 24 2.1.4. Supplementary data ............................................................................................................ 25 2.2. Experimental data for Chapter 3 ............................................................................................... 25 2.2.1. Stoichiometric reactions of GI, GII, and GII’ with N-donors ............................................ 25 2.2.2. Syntheses of new compounds ............................................................................................. 26 2.2.3. Characterization data for benzylidene abstraction products ............................................ 27 2.3. Experimental data for Chapter 4 ............................................................................................... 28 2.3.1. Experimental details for Chapter 4, Sections 4.1-4.3 ........................................................ 28 2.3.2. Experimental details for Chapter 4, Section 4.4. ............................................................... 32 2.4. Experimental data for Chapter 5 ............................................................................................... 33 2.4.1. Syntheses of GII adducts of pyrroldine and morpholine (Section 5.2.1) ........................... 33 2.4.2. Syntheses of other new Ru benzylidenes ............................................................................ 34 2.4.3. Olefin metathesis ................................................................................................................ 37 2.4.2. Decomposition studies ....................................................................................................... 37 2.4.3. Reactions of Ru alkylidenes with lithium salts ................................................................... 39 2.4.4. Experimental details for Chapter 5, Section 5.6 ................................................................ 40 2.6. References ................................................................................................................................. 44 Chapter 3. Decomposition of the Grubbs Catalysts by Amines: Benzylidene Abstraction ............... 46 3.1. Introduction ............................................................................................................................... 46 3.2. Decomposition of the first-generation Grubbs catalyst GI by benzylidene abstraction ........... 50 3.2.1. Unexpected abstraction of the benzylidene ligand from GI by n-butylamine .................... 50 3.2.2. Benzylidene abstraction from an ethylenediamine (en) derivative of GI .......................... 53 3.3. Reactions of GII with primary amines ...................................................................................... 54 3.3.1. Benzylidene abstraction by n-butylamine: identification of products ............................... 54 3.3.2. Benzylidene abstraction from amine adducts of GII as compared with GII ...................... 57 3.3.3. Reactions of GII with larger primary amines .................................................................... 58 II 3.3.4. Proposed mechanism for benzylidene abstraction by primary amines .............................. 60 3.4. Reactions of GII with secondary amines and larger N-donors ................................................. 62 3.5. Conclusions and future work ..................................................................................................... 63 3.6. References ................................................................................................................................. 64 Chapter 4. The Impact of Nitrogen Bases on the Stability and Metathesis Performance of the Hoveyda Catalyst: Alkylidene and Proton Abstraction Pathways ....................................................... 66 4.1. Introduction ............................................................................................................................... 66 4.2. Adduct formation on reaction of HII with N-donors ................................................................. 68 4.3. Base-induced decomposition of HII and its active species during metathesis .......................... 73 4.4. Subsequent advances ................................................................................................................. 79 4.4.1. C–H activation of the N-heterocyclic carbene during metallacyclobutane decomposition ...................................................................................................................................................... 79 4.4.2. Can GII decompose via deprotonation of the metallacyclobutane? .................................. 82 4.4.3. Impact of N-donors on CM yield: GII vs. HII .................................................................... 82 4.4.4. The role of amine basicity in determining the decomposition pathway for GII ................ 84 4.4.5. Metallacyclobutane deprotonation with GII – ethenolysis ................................................ 85 4.4.6. Alkylidene abstraction from HII during catalysis .............................................................. 86 4.5. Conclusions and future work ..................................................................................................... 90 4.6. References ................................................................................................................................. 92 Chapter 5. Amines as Ligands in Olefin Metathesis ........................................................................... 95 5.1. Nitrogen ligands in olefin metathesis – design opportunities ................................................... 95 5.2. Synthesis of Ru benzylidenes with amine ligands ...................................................................... 97 5.2.1. Synthesis and characterization of Grubbs benzylidenes with monodentate amine ligands ...................................................................................................................................................... 97 5.2.2. Synthesis and characterization of benzylidene complexes with chelating diamines. ........ 99 5.3. Olefin metathesis studies with biphenylamine catalysts .......................................................... 104 5.4. Decomposition studies of biphenyldiamine derivatives .........................................................