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

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

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

Photocatalyst : What is? 4 conjugate systerm facilitates electron transfer

Photocatalyst : What is? 5

generation of excited state 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. Science 1997, 275, 54 6

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) 7 Prier, C. K.; Rankic, D. A.; MacMillan, D. W. C. Chem. Rev. 2013, 113, 5322 Scholes, G. D. Annu. Rev. Phys. Chem. 2003, 54, 57

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

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

Conversion of N–O bond Proposed mechanism MacMillan Group 10 We report herein a visible light induced generation of a carbanion via double-SET and its application in cyclopropanation of alkenes. This new synthetic approach to form cyclopropane derivatives was conducted under mild conditions, using sunlight in open air, showing the features such as environmental benignness and an easy to handle procedure. Proposed mechanism MacMillan Group 10 J. Am. Chem. Soc. 2013, 135, 11521

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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