Visible light photoredox-controlled reactions of N-radicals

1. Literature Report Visible light photoredox-controlled reactions of N-radicals Reporter: Leifeng Wang Prof. Huang Group Meeting March 21th 2016

2. Contents I: Background Photocatalyst : What is? Photocatalyst : What for? II: Photoredox-controlled reactions of N-radicals Conversion of N–O and N–S bonds into N-centred radicals Conversion of N–N bonds into N-centred radicals Conversion of N–X bonds into N-centred radicals Conversion of N–H bonds into N-centred radicals III: Summary

3. Photocatalyst : What is? In catalysed photolysis, light is absorbed by an adsorbed substrate. In photogenerated catalysis, the photocatalytic activity (PCA) depends on the ability of the catalyst to create electron–hole pairs, which generate free radicals (e.g. hydroxyl radicals: •OH) able to undergo secondary reactions. http://en.wikipedia.org/wiki/Photocatalyst Rudolph Marcus Won Nobel Prize in Chemistry for Marcus Theory of Electron Transfer in 1992. 3 http://en.wikipedia.org/wiki/Rudolph_A._Marcus

4. Photocatalyst : What is? 4 conjugate systerm facilitates electron transfer

5. Photocatalyst : What is? 5

6. Photocatalyst : What For? photon absorption and generation of excited state a short-lived singlet excited state rapidly converts to a long-lived triplet Juris, A.; Balzani, V. ; Barigelletti, F.; Campagna, S.; Belser, P. ; Von Zelewsky, A. Coord. Chem. Rev. 1988, 84, 85 Damrauer, N. H.; Cerullo, G.; Yeh, A.; Boussie, T. R.; Shank, C. V. ; McCusker, J. K. Science1997, 275, 54 6

7. Excited State can Relax through a Variety of Pathways I: Single Electron Transfer (SET) II: Energy Transfer (ET) occurs through space (1 – 10 nm) differences are how substrates are engaged and distance from which transfer occurs excited photocatalyst has extra energy (1.5 – 3 eV) and can do productive chemistry occurs through physical contact (< 0.01 nm) Prier, C. K.; Rankic, D. A.; MacMillan, D. W. C. Chem. Rev. 2013, 113, 5322 7 Scholes, G. D. Annu. Rev. Phys. Chem. 2003, 54, 57

8. Contents I: Background Photocatalyst : What is? Photocatalyst : What for? II: Photoredox-controlled reactions of N-radicals Conversion of N–O and N–S bonds into N-centred radicals Conversion of N–N bonds into N-centred radicals Conversion of N–X bonds into N-centred radicals Conversion of N–H bonds into N-centred radicals III: Summary

9. Contents I: Background Photocatalyst : What is? Photocatalyst : What for? II: Photoredox-controlled reactions of N-radicals Conversion of N–O and N–S bonds into N-centred radicals Conversion of N–N bonds into N-centred radicals Conversion of N–X bonds into N-centred radicals Conversion of N–H bonds into N-centred radicals III: Summary

10. Conversion of N–O bond Proposed mechanism MacMillan Group 10 J. Am. Chem. Soc. 2013, 135, 11521

11. Conversion of N–O bond Proposed mechanism Sanford group 11 J. Am. Chem. Soc. 2014, 136, 5607 Chem. Soc., 2014, 136, 5607

12. Conversion of N–O bond S.-Y. Yu group Org. Lett. 2014, 16, 3504 12

13. Conversion of N–O bond S.-Y. Yu group Angew. Chem. Int. Ed. 2015, 54, 4055 13

14. Conversion of N–O bond S.-Y. Yu group Angew. Chem. Int. Ed. 2015, 54, 4055 14

15. Conversion of N–O bond Leonori group Angew. Chem. Int. Ed. 2015, 54, 14017 15

16. Conversion of N–S bond W.-J. Xiao group Chem. – Asian J. 2013, 8, 1090 16

17. Contents I: Background Photocatalyst : What is? Photocatalyst : What for? II: Photoredox-controlled reactions of N-radicals Conversion of N–O and N–S bonds into N-centred radicals Conversion of N–N bonds into N-centred radicals Conversion of N–X bonds into N-centred radicals Conversion of N–H bonds into N-centred radicals III: Summary

18. Conversion of N–N bond Studer group Org. Lett. 2014, 16, 254 17

19. Conversion of N–N bond Studer group Org. Lett. 2014, 16, 254 18

20. Conversion of N–N bond Akita group Chem. – Eur. J. 2015, 21, 11677 20

21. Conversion of N–N bond Liu group Nat. Chem. 2011, 3, 146 21

22. Contents I: Background Photocatalyst : What is? Photocatalyst : What for? II: Photoredox-controlled reactions of N-radicals Conversion of N–O and N–S bonds into N-centred radicals Conversion of N–N bonds into N-centred radicals Conversion of N–X bonds into N-centred radicals Conversion of N–H bonds into N-centred radicals III: Summary

23. Conversion of N–X bond Lee Group Chem.Commun. 2014, 50, 9273 Xue Group Synlett. 2014, 2013-2018. 22

24. Conversion of N–X bond S.-Y. Yu group Org. Lett. 2015, 17, 1894 Org. Biomol. Chem. 2015, 13, 10295 23

25. Conversion of N–X bond S.-Y. Yu group Org. Lett. 2015, 17, 1894 23

26. Contents I: Background Photocatalyst : What is? Photocatalyst : What for? II: Photoredox-controlled reactions of N-radicals Conversion of N–O and N–S bonds into N-centred radicals Conversion of N–N bonds into N-centred radicals Conversion of N–X bonds into N-centred radicals Conversion of N–H bonds into N-centred radicals III: Summary

27. Conversion of N–H bond 24 W.-J. Xiao group Angew. Chem. Int. Ed. 2015, 54, 14017

28. Conversion of N–H bond Knowles Group J. Am. Chem. Soc. 2015, 137, 9226 J. Am. Chem. Soc. 2015, 137, 13492 25

29. Contents I: Background Photocatalyst : What is? Photocatalyst : What for? II: Photoredox-controlled reactions of N-radicals Conversion of N–O and N–S bonds into N-centred radicals Conversion of N–N bonds into N-centred radicals Conversion of N–X bonds into N-centred radicals Conversion of N–H bonds into N-centred radicals III: Summary

30. Summary Challenges Remain: 1) the activation of other more challenging N–H bonds and exploration of new reaction modes 2) the asymmetric variants of N-radicals and radical ion-mediated reactions

31. Thank You for Your kind attention!