University of Groningen
Dynamic transfer of chirality in photoresponsive systems
Pizzolato, Stefano Fabrizio
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Publication date: 2017
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Pizzolato, S. F. (2017). Dynamic transfer of chirality in photoresponsive systems: Applications of molecular photoswitches in catalysis. University of Groningen.
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Dynamic Transfer of Chirality in Photoresponsive Systems
Applications of Molecular Photoswitches in Catalysis
Dynamic Transfer of Chirality in Photoresponsive Systems: Applications of Molecular Photoswitches in Catalysis
Stefano Fabrizio Pizzolato PhD Thesis
University of Groningen
ISBN: 978-94-034-0249-9 (printed version) 978-94-034-0248-2 (electronic version)
Print: Ipskamp drukkers B.V., Enschede, The Netherlands
The work described in this thesis was carried out at the Zernike Institute for Advanced Materials and Stratingh Institute for Chemistry, in compliance with the requirements of the Graduate School of Science (Faculty of Mathematics and Natural Sciences, University of Groningen)
Dynamic Transfer of Chirality in
Photoresponsive Systems
Applications of Molecular Photoswitches in Catalysis
PhD thesis
to obtain the degree of PhD at the
University of Groningen
on the authority of the
Rector Magnificus Prof. E. Sterken
and in accordance with
the decision by the College of Deans.
This thesis will be defended in public on
Friday 1 December 2017 at 14.30 hours
by
Stefano Fabrizio Pizzolato
born on 17 March 1988
Supervisor Prof. B.L. Feringa Assessment Committee Prof. S. Harutyunyan Prof. H. Hiemstra Prof. J.G. de Vries
To my wife Susanna,
Table of Contents
1. Photoswitchable Systems for Dynamic Transfer of Chirality 1
1.1 Chirality 2
1.2 Organic photoswitchable molecules 2
1.3 Dynamic stereochemistry and molecular motors 5
1.3.1 Chirality sets the way 5
1.3.2 Control of single-molecule motion 5
1.3.3 Liquid crystal and supramolecular structure morphology 7
1.3.4 Polymers morphology 10
1.3.5 Stereoselective catalysis 16
1.3.6 Host-guest interaction and chiral recognition 19
1.3.7 Photocontrol of biological systems 22
1.4 Conclusions 25
1.5 Aim and outline of the thesis 26
1.6 References 28
2. Spectroscopic and Theoretical Identification of Two Thermal Isomerization Pathways for Bistable Chiral Overcrowded Alkenes 33
2.1 Introduction 34
2.1.1 Photo- and thermally-responsive molecular switches 34
2.1.2 Second generation molecular motors 34
2.2 Results and discussion 35
2.2.1 Design 35
2.2.2 Synthesis 36
2.2.3 Photochemical and thermal isomerizations 39
2.2.4 Computational results 47
2.2.5 Photoswitching process 50
2.2.6 Full experimental study of stable E-isomer isomers 52
2.3 Conclusions 56
2.4 Acknowledgements 56
2.5 Experimental section 57
2.6 References 69
3. Bifunctional Molecular Photoswitches based on Overcrowded Alkenes for Dynamic Control of Catalytic Activity in Michael Addition Reactions 71
3.1 Introduction 72
3.1.1 Photocontrol of catalytic functions 72
3.1.2 Unique features of molecular motors 73
3.2 Results and discussion 75
3.2.1 Design 75
3.2.2 Synthesis 76
3.2.3 Photoswitching process 80
3.2.4 Catalytic activity 84
3.3 Conclusions 88
3.4 Acknowledgements 88
3.5 Experimental section 89
3.6 References 115
4. Studies towards a Trifunctionalized Molecular Switch for Light-assisted Tandem Catalytic
Processes 119
4.1 Introduction 120
4.2 Results and discussion 126
4.2.1 Design 126
4.2.2 Preliminary testing of bifunctional overcrowded alkenes as switchable catalysts 131
4.2.3 Attempted synthesis of alternative bifunctionalized switches 132
4.2.4 Investigation of catalytic performance in alternative organocatalyzed transformations 136
4.3 Conclusions 142
4.4 Acknowledgements 143
4.5 Experimental section 143
4.6 References 147
5. Central-to-Helical-to-Axial-to-Central Transfer of Chirality with a Photoresponsive
Catalyst 151
5.1 Introduction 153
5.2 Results and Discussion 153
5.2.1 Design and modeling calculations 153
5.2.2 Synthesis 157
5.2.3 NMR spectroscopy and atropisomer assignment 159
5.2.4 Atropisomerization process 164
5.2.5 Photochemical isomerization 171
5.2.6 Switchable asymmetric catalysis 175
5.3 Conclusions 177
5.4 Acknowledgements 178
5.5 Experimental section 178
5.6 References 194
6. Phosphoramidite-Molecular Switches as Photoresponsive Ligands Displaying Multifold
Transfer of Chirality in Dynamic Enantioselective Metal Catalysis 197
6.1 Introduction 198
6.2 Results and Discussion 199
6.2.1 Design 199
6.2.2 Synthesis 201
6.2.3 Photochemical isomerization 202
6.2.4 Assignment of 1H NMR absorptions of (M) and (P) isomers of L2 via 1D-2D NMR
techniques 205
6.2.5 X-ray crystallography 209
6.2.6 Switchable asymmetric catalysis 210
6.3 Conclusions 214
6.4 Acknowledgements 214
6.5 Experimental section 215
7. Studies towards a Photoswitchable Chiral Organic Phosphoric Acid based on an Overcrowded Alkene for Organocatalyzed Asymmetric Transformations 235
7.1 Introduction 236
7.2 Results and discussion 238
7.2.1 Design 238
7.2.2 Synthesis 242
7.2.3 NMR spectroscopy 242
7.2.4 Photochemical isomerization. 244
7.2.5 Switchable asymmetric catalysis. 244
7.2.6 Attempted synthesis of 3,3‘-distituted biaryl switch core 246
7.3 Conclusion 251
7.4 Experimental section 252
7.5 References 257
8. Study towards a Photoswitchable Chiral Bidentate Phosphine Ligand based on an
Overcrowded Alkene for Metal-catalyzed Asymmetric Transformations 259
8.1 Introduction 260
8.1.1 Design of natural and artificial metal complexes 260
8.1.2 Asymmetric transformation of stereodynamic biaryls 260
8.1.3 Photoswitchable metal complexes for asymmetric catalysis 262
8.2 Results and discussion 265
8.2.1 Design 265
8.2.2 Retrosynthetic analysis 268
8.2.3 Derivatization of resolved bisphenol derivative 269
8.2.4 Metal-catalyzed phosphorylation 270
8.2.5 Phosphine oxide reduction 272
8.2.6 Attempted second metal-catalyzed phosphorylation 275
8.2.7 Development of photoswitchable chiral Brønsted acid 278
8.3 Conclusions 283
8.4 Experimental section 285
8.5 References 289
Summary 293
Samenvatting 299
Abbreviations and Acronyms 305
Acknowledgements 307
