University of Groningen
Copper-catalyzed enantioselective conjugate addition of Grignard reagent to non-activated acceptors
Yan, Xingchen
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Publication date: 2019
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Yan, X. (2019). Copper-catalyzed enantioselective conjugate addition of Grignard reagent to non-activated acceptors. University of Groningen.
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Stellingen
Behorende bij het proefschrijft
Copper-catalyzed enantioselective conjugate addition of Grignard reagent to non-activated acceptors enabled by Lewis acid
van Xingchen Yan
1. Some projects appear easy, but are actually quite difficult in practice. Some projects appear difficult, but end up running smoothly. Therefore, there is no point in asking your supervisor for an ‘easy’ project.
2. The asymmetric conjugate addition of Grignard reagent to (E)-N,N-dimethyl-6-bromo-hex-2-enamide followed by intramolecular trapping was discovered by accident (Chapter 2): we anticipated only an asymmetric addition, but finally found that the intermediate silyl enolate cyclized to form an interesting product. Therefore, it is worthful to analyze the unexpected result you obtained, because perhaps you can find something interesting.
3. Lewis acids and Grignard reagents are unstable, so when a reaction fails or is irreproducible, the quality of the reagents should be considered first.
4. Photocatalysis is a powerful tool that can enable uncommon transformations, but the reactions are difficult to repeat. This is often because those reporting them forget that light is a reagent.
5. In the asymmetric conjugate addition of Grignard reagents to α,β-unsaturated carboxamides, replacing methyl with allyl as the protecting group can lead to much better results (Chapter 2). Asymmetric catalysis is so sensitive to the structure of the substrate that sometimes a minor change in structure leads to completely different outcomes. Learning how to predict these changes would accelerate research.
6. Coming up with propositions requires that you first figure out what a proposition is. The graduate school should run a course on it.
