Metallaphotoredox Catalysis (Including my work in Shū Kobayashi group from Oct to Aug. 2015)

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1 tallaphotoredox (ncluding my work in Shū Kobayashi group from ct to Aug. 2015) otoredox Transition tal Tatsuhiro Tsukamoto Literature Talk: Jan. 6 th, 2016 the Dong group 1

2 Contents 1. Visible Light otoredox (PC) 2. PC + Transition tal (i, Pd, Pt, ) 3. My Previous Work (PC + ) 2

3 Visible Light as a Promising Energy Source Fossil Fuels is non-renewable, hazardous will be no longer available Sunlight nearly limitless energy Solar Energy Distribution 400 nm 700 nm 3

4 otoredox Catalyst as edox diator a Ca Br Br Br Br u 2+ t Bu t Bu r + ose Bengal (λ max = 549 nm) Eosin Y (λ max = 524 nm) u(bpy) 3 (PF 6 ) 2 (λ max = 456 nm) r(ppy) 2 (dtbbpy)pf 6 (λ max = 416 nm) r visible light MLCT V r r(ppy) 3 r(ppy) 3 * q rradiated photoredox catalyst works as both oxidant and reductant. 4

5 Visible Light otoredox D: amines enamines olefins D [r(ppy) 3 ] A A: benzophenones alkyl halides enones D V xidative Quenching Cycle 1.73 V A r visible light MLCT V r A r(ppy) V eductive Quenching Cycle V A: benzophenones alkyl halides enones [r(ppy) 3 ] A C. K. Prier, D. A. ankic, D. W. C. MacMillan, Chem. ev. 2013, 113, D r(ppy) 3 * D D: amines enamines olefins 5

6 otoredox eactions n eductive X X = Br, u(bpy) 3 2 (5 mol%) Acr 2 (1.0 eq.) 4, C, visible light rt, 8-20 h 84% quant. u u(bpy) Acr 2 S. Fukuzumi, S. Mochizuki, T. Tanaka, J. ys. Chem. 1990, 94, X X + X u visible light otoredox u * u 6

7 otoredox eactions n eductive = 1º & 2º alkyl alkenyl, aryl fac-r(ppy) 3 (1 mol%) Bu 3 (2 5 eq.) antzch ester (2.0 eq.) or C 2 (5.0 eq.) C, visible light rt, h 21 examples 83 99% r r(ppy) 3 Et Et antzch ester J. D. guyen, E. M. D'Amato, J. M.. arayanam, C.. J. Stephenson, ature Chem. 2012, 4, 854. visible light electron donor [electron donor] r otoredox r * -atom transfer by-products r -atom transfer Et Et Bu 2 Pr C 2 7

8 otoredox eactions n edox-neutral 1 + J. Du and T. P. Yoon, J. Am. Chem. Soc. 2009, 131, u(bpy) 3 2 (5 mol%) i Pr 2 Et, LiBF 4 C, rt, 4 h 1 2 up to 88%, 10:1 dr u u(bpy) % >10:1 dr 82% >10:1 dr 53% >10:1 dr 74% >10:1 dr Et 70% 6:1 dr i Pr 64% >10:1 dr t Bu 8% >10:1 dr Bn 2 C 61% >10:1 dr Et SEt 76% >10:1 dr 65% 5:1 dr 88% >10:1 dr 61% >10:1 dr 8

9 otoredox eactions n edox-neutral 2+ EDG 1 + u(bpz) 3 (BF) 2 (0.5 mol%) EDG 2 2 DCM, 23W CFL air, rt 1 18 examples, 42 98% u u(bpz) 3 2+ S. Lin, M. A. schay, C. G. Fry, T. P. Yoon, J. Am. Chem. Soc. 2011, 133, visible light 2 2 u otoredox u * u

10 otoredox eactions n edox-neutral n r(ppy) 2 (dtbbpy)pf 6 (2 mol%) + t 1 2 Bu, visible light rt, 12 h n r ( eq.) 1 2 t Bu 25 examples, 27 98% r(ppy) 2 (dtbbpy) + + n C C cleavage n J. Wang,. Zhang, Angew. Chem. nt. Ed. 2015, 54, % t Bu 57% F 3 C 92% C 2 Et 95% 10

11 otoredox eactions n xidative 1 r(df(cf 3 )ppy) 2 (dtbbpy)pf 6 (1 mol%) 2 C 2 2, rt, visible light h examples, 27 96% F 3 C + t F Bu F r F t Bu F F 3 C r(df(cf 3 )ppy) 2 (dtbbpy) + A. G. Condie, J. C. González-Gómez, C.. J. Stephenson, J. Am. Chem. Soc. 2010, 132, r otoredox r visible light r *

12 otoredox eactions n xidative X Δ-u(menbpy) 3 (0.5 mol%) Co(acac) 3 (1.2 eq.) C, visible light rt X =, 4% ee Δ-u(menbpy) 3 X =, 16% ee T. amada,. shida, S. Usui, Y. Watanabe, K. Tsumura, K. hkubo, J. Chem. Soc. Chem. Commun. 1993, 909. X X u 3 = X X slow X X u * + otoredox u u Co(acac) 2 + acac X X u * otoredox u fast (S) () X X X Co(acac) 3 u Co(acac) 2 + acac Co(acac) 3 12

13 Contents 1. Visible Light otoredox (PC) 2. PC + Transition tal (i, Pd, Pt, ) 3. My Previous Work (PC + ) 13

14 Transition tal and otoredox u M n+ X eductive Elimination xidative Addition Transiton tal u M (n+2)+ X M (n+2)+ Ligand Exchange or Transmetalation u p Two-electron redox pathway 14

15 tallaphotoredox M n+ u eductive Elimination u PC Transition tal M (n+2)+ SET blue LED otoredox PC * M (n+1)+ u M (n+1)+ u Ligand Exchange or Transmetalation PC SET + X X chanistic Concept from my previous work (W.-J.Yoo, T. Tsukamoto, S. Kobayashi, rg. Lett. 2015, 17, 3640.) p Single-electron oxidation of metal species p Single-electron reduction of alkyl halide 15

16 First example in tallaphotoredox n Sonogashira coupling Br + =, Si 3 [Pd(C) 2 ] 2 (4 mol%) u(bpy) 3 (PF 6 ) 2 (8 mol%) P( t Bu) 3 (4 mol%) Et 3 /DMF = 1/4, rt 150 W Xe lamp 9 examples, 85 99% GC yield (w/o hv: trace 36% GC yield) u u(bpy) M. sawa,. agai, M. Akita, Dalton Trans. 2007, 827. (a): Under light irradiation (b): Dark (dash line) (c): n and off 16

17 tallaphotoredox Palladium- n Directed C activation DG Pd(Ac) 2 (10 mol%) r(ppy) 2 (dtbbpy)pf 6 (5 mol%) [ 2 ]BF 4 (2.0 eq.) 26 W lightbulb, rt, 4 10 h DG t Bu t Bu r r(ppy) 2 (dtbbpy) + + D. Kalyani, K. B. McMurtrey, S.. ewfeldt, M. S. Sanford, J. Am. Chem. Soc. 2011, 133, L C DG = L C L C L C V Pd r i visible light L C Pd Transition tal otoredox r i * L C Pd r V [ 2 ]BF BF 4 17

18 tallaphotoredox Palladium- n Cross Dehydrogenative Coupling 1 2 C 2 3 Pd(Ac) 2 (10 mol%) r(ppy) 2 (ppy)pf 6 (3 mol%) K 2 C 3 (3.0 eq.) 11 W lamp, DMF rt, 24 h C r r(ppy) 2 (dtbbpy) + + J. Zoller, D. C. Fabry, M. A. onge, M. ueping, Angew. Chem. nt. Ed. 2014, 53, C 2 Ac Ac Pd C 2 Pd(Ac) 2 2 Transition tal [] r 2 Ac Pd C 2 otoredox [Pd 0 ] r * C 2 r visible light 18

19 tallaphotoredox -Gold- n edox-neutral Cyclization 3 Y 2 n Y =, Ts n = 1, BF 4 4 Au(P 3 )Tf 2 (10 mol%) u(bpy) 3 (PF 6 ) 2 (2.5 mol%), 23 W lamp rt, 4 12 h Y 2 1 (4.0 eq.) 18 examples, % B. Sahoo, M.. opkinson, F. Glorius, J. Am. Chem. Soc. 2013, 135, product 3 P reductive elimination Au 3 P Au 3 u n visible light 4 u u(bpy) P Au Transition tal 3 P Au otoredox u * u [ 2 ]BF BF 4 19

20 tallaphotoredox -Gold- n edox-neutral ing expansion 2+ n + 2 BF 4 (3.0 eq.) Au(P 3 ) (10 mol%) u(bpy) 3 (PF 6 ) 2 (2.5 mol%) /C, visible light rt, 5 24 h n 26 examples, % u u(bpy) 3 2+ X.-Z. Shu, M. Zhang, Y. e,. Frei, F. D. Toste, J. Am. Chem. Soc. 2014, 136,

21 tallaphotoredox -ickel- n Suzuki Miyaura coupling of aryl halide and sp 3 -hybridized BF 3 K 1 BF 3 K Br 2 1 PF 6 (2 mol%) i(cd) 2 (3 mol%) dtbbpy (3 mol%) xidative Addition 2,6-lutidine (3.5 eq.) Acetone/ (1/1) 26W CFL, rt, 24 h J. C. Tellis, D.. Primer, G. A. Molander, Science 2014, 345, Br F 3 C F r 1 F F + F CF 3 1 L L L L i i 2 Br 2 Br ickel 1 eductive Elimination L L L L i 0 i 2 r [r] blue LED otoredox SET X SET p Driven by the one-electron oxidation of organic molecule. r * 1 BF 3 K 21

22 tallaphotoredox -ickeln Decarboxylative coupling of α-amino acids and aryl halides Boc + X F 3C r(df(cf 3)ppy)2(dtbbpy)PF6 (1 mol%) i 2 glyme (10 mol%) dtbbpy (15 mol%) DMF, 26 W CFL 23 ºC, 72 h tbu r F Boc F tbu F 3C + F F (X =, Br, ) r(df(cf 3)ppy)2(dtbbpy)+ Z. Zuo, D. T. Ahneman, L. Chu, J. A. Terrett, A. G. Doyle, D. W. C. MacMillan, Science 2014, 345,

23 tallaphotoredox -Coppern Trifluoromethylation 2+ B() 2 + CF3 (5.0 eq.) Ac (20 mol%) u(bpy) (1 mol%) K 2C3 (1.0 eq.), DMF 26W lightbulb 60 ºC, 12 h CF3 22 examples, 39 93% u u(bpy) 32+ Y. Ye, M. S. Sanford, J. Am. Chem. Soc. 2012, 134,

24 Contents 1. Visible Light otoredox (PC) 2. PC + Transition tal (i, Pd, Pt, ) 3. My Previous Work (PC + ) 24

25 tallaphotoredox M n+ u eductive Elimination u PC Transition tal M (n+2)+ SET blue LED otoredox PC * M (n+1)+ u M (n+1)+ u Ligand Exchange or Transmetalation PC SET + X X chanistic Concept from my previous work (W.-J.Yoo, T. Tsukamoto, S. Kobayashi, rg. Lett. 2015, 17, 3640.) p Single-electron oxidation of metal species p Single-electron reduction of alkyl halide 25

26 Topics 1. Visible-Light-diated Chan Lam Coupling eaction B() oto Copper edox Cat. Cat. 2. Visible-Light-diated C Ullmann-type Coupling eaction + oto edox Cat. Copper Cat. 26

27 Chan-Lam Coupling eactions (1) 1 X + B() 2 X =,, S 2 salt solvent rt 1 X 2 D. M. T. Chan, K. L. Monaco,.-P. Wang, M. P. Winters, Tetrahedron Lett. 1998, 39, D. A. Evans, J. L. Katz, T.. West, Tetrahedron Lett. 1998, 39, P. Y. S. Lam, C. G. ark, S. Saubern, J. Adams, M. P. Winters, D. M. T. Chan, A. Combs, Tetrahedron Lett. 1998, 39, p Stoichiometric salt 2 + B() 2 cat. (Ac) 2 cat. myristic acid 2,6-lutidine, solvent rt, open air vigorous stirring J. C. Antilla, S. L. Buchwald. rg. Lett. 2001, 3, p Catalytic amount of species p Limited substrate scope = Alkyl, : 50 91% = p-: <10% (GC) C 2 12 myristic acid 27

28 Chan-Lam Coupling eactions (1) eductive Elimination slow Copper [] 2 1 Ligand Exchange & Transmetallation B() B() 2 cat. (Ac) 2 cat. myristic acid 2,6-lutidine, solvent rt, open air vigorous stirring J. C. Antilla, S. L. Buchwald. rg. Lett. 2001, 3, p Catalytic amount of species p Limited substrate scope = Alkyl, : 50 91% = p-: <10% (GC) C 2 12 myristic acid 28

29 Chan-Lam Coupling eactions (2) B() 2 oto edox Cat. Copper Cat. 1 2 otoredox/copper Dual [] by 2 slow electron-poor [] by photoredox catalyst acceleration electron-poor 29

30 Control Experiments 2 + (1.5 eq.) B() 2 r(ppy) 3 (1 mol%) (Ac) 2 (10 mol%) myristic acid (20 mol%) 2,6-lutidine (1.0 eq.) C/ (1/1), 35 ºC open air, blue LED 20 h r r(ppy) 3 C 2 12 myristic acid Screened conditions p Visible light photoredox catalysts p Transition metal catalysts p Solvents entry r(ppy) 3 blue LED (Ac) 2 & myristic acid yield [%] [a] >95 [a] Determined by 1 -M analysis using 1,1,2,2-tetrachloroethane as an internal standard. 30

31 Substrate Scope (1) 2 + (1.5 eq.) B() 2 r(ppy) 3 (1 mol%) (Ac) 2 (10 mol%) myristic acid (20 mol%) 2,6-lutidine (1.0 eq.) C/ (1/1), 35 ºC open air, blue LED 20 h r r(ppy) 3 C 2 12 myristic acid 93% (7%*) Quant. (23%*) 95% (11%*) Quant. (12%*) 43% (37%*) Br 91% (7%*) Quant. (9%*) C 71% (15%*) Et 2 C Ac 42% (11%*) 47% (13%*) *in the absence of r(ppy) 3 and blue LED irradiation. F 3 C 72% (15%*) 55% (10%*) 31

32 Substrate Scope (2) 2 + B() 2 (1.5 eq.) r(ppy) 3 (1 mol%) (Ac) 2 (10 mol%) myristic acid (20 mol%) 2,6-lutidine (1.0 eq.) C/ (1/1), 35 ºC open air, blue LED 20 h r r(ppy) 3 C 2 12 myristic acid Br F CF 3 89% (12%*) 93% (7%*) 79% (12%*) 85% (19%*) C Ac C 2 43% (5%*) 47% (18%*) 62% (19%*) 65% (17%*) *in the absence of r(ppy) 3 and blue LED irradiation. 32

33 chanistic Study (1) B() 2 oto edox Cat. Copper Cat. 1 2 r q Proposed chanism A blue LED r 1 otoredox/copper Dual 2 eductive Elimination 2 1 r(ppy) 3 Visible light photoredox catalyst helps the formation of () species. r * otoredox Copper [] q Stern Volmer Plot 2 2 r V 2 1 Ligand Exchange & Transmetallation B() 2 q Kinetic Study q Anaerobic eaction 33

34 chanistic Study (2) q Stern-Volmer Plot Study fac-r(ppy) 3 solutions ( mm in C) were excited at 320 nm and the emission intensity at 518 nm was observed / 1 0 / 2 0 / Cyanophenyl boronic Acid [M] Aniline [M] ,6-Lutidine [M] / / Copper() Acetate [M] Chloro--phenylaniline [M] q r(ppy) 3 * can react only with (Ac) 2 and the product. 34

35 chanistic Study (3) q Proposed chanism B eductive Elimination 2 1 blue LED r r * otoredox Copper [] 2 r V Ligand Exchange & Transmetallation B() 2 35

36 chanistic Study (4) q Kinetic Study 2 + GC yield (%) (1.5 eq.) B() 2 r(ppy) 3 (1 mol%) (Ac) 2 (10 mol%) myristic acid (20 mol%) 2,6-lutidine (1.0 eq.) C/ (1/1), 35 ºC open air, blue LED 20 h Time (min) r r(ppy) 3 q Proposed chanism B is not major pathway. 36

37 chanistic Study (5) q Proposed chanism C eductive Elimination 2 1 blue LED r 1 2 r * otoredox Copper [] 2 r V Ligand Exchange & Transmetallation B() 2 37

38 chanistic Study (6) q Anaerobic eaction 2 + (1.5 eq.) B() 2 r(ppy) 3 (1 mol%) (Ac) 2 (X eq.) myristic acid (20 mol%) 2,6-lutidine (1.0 eq.) C/ (1/1), 35 ºC atmosphere, blue LED 20 h r r(ppy) 3 entry r(ppy) 3 blue LED (Ac) 2 (X eq.) atmosphere yield [%] [a] 1 10 mol% eq eq. 28 [a] solated yield. q Proposed chanism C is not major pathway. q Proposed chanism A is most reasonable. 38

39 Topics 1. Visible-Light-diated Chan Lam Coupling eaction B() oto Copper edox Cat. Cat. 2. Visible-Light-diated C Ullmann-type Coupling eaction + oto edox Cat. Copper Cat. 39

40 C Ullmann-type Coupling eaction (1) C 2 + (powder) C ºC F. Ullmann, Ber. Dtsch. Chem. Ges. 1903, 36, p Stoichiometric p igh temperature X X = C, + (1.4 eq.) (10 mol%) Li t Bu (1.4 eq.) C or C/ t Bu hv (254 nm), rt X D. T. Ziegler, J. Choi, J. M. Muñoz-Molina, A. C. Bissember, J. C. Peters, G. C. Fu, J. Am. Chem. Soc. 2013, 135, p Catalytic p oom temperature p armful light source, UV 40

41 C Ullmann-type Coupling eaction (1) X X = C, + (1.4 eq.) (10 mol%) Li t Bu (1.4 eq.) C or C/ t Bu hv (254 nm), rt X t Bu Li X 2 Li t Bu 2 2 Li B UV irradiation X 2 Li A Copper * 2 2 Li C 2 1 electron transfer 1 X Li X D Li X 2 = carbazolide X = halide 41

42 C Ullmann-type Coupling eaction (2) + oto edox Cat. Copper Cat. Visible light as alternative energy! blue LED r F Ligand Exchange G r * otoredox SET Copper SET + r V E eductive Elimination 42

43 ptimization r r(ppy) 3 F F F r F r(dfppy) 3 photocatalyst (2 mol%) (10 mol%) + (X eq.) Li t Bu (1.5 eq.), solvent (0.25 M) light source, rt, 18 h entry solvent photocatalyst light source X (eq.) yield (%) [a] 1 DMS r(ppy) 3 white LED DMS r(dfppy) 3 white LED DMS r(ppy) 2 (dtbbpy)pf 6 white LED DMS r(df(cf 3 )ppy) 2 (dtbbpy)pf 6 white LED DMS u(dtbbpy) 3 2PF 6 white LED DMS u(bpz) 3 2PF 6 white LED [a] Determined by 1 -M analysis using 1,1,2,2-tetrachloroethane as an internal standard. F F t Bu t Bu r r(ppy) 2 (dtbbpy) + + t Bu t Bu F CF 3 r r(df(cf) 3 ppy) 2 (dtbbpy) + F F + F CF 3 t Bu t Bu t Bu u t Bu 2+ t Bu t Bu u u(dtbbpy) 3 2+ u(bpz)

44 ptimization photocatalyst (2 mol%) (10 mol%) + (X eq.) Li t Bu (1.5 eq.), solvent (0.25 M) light source, rt, 18 h r r(ppy) 3 entry solvent photocatalyst light source X (eq.) yield (%) [a] 1 DMS r(ppy) 3 white LED DMS r(dfppy) 3 white LED DMS r(ppy) 2 (dtbbpy)pf 6 white LED DMS r(df(cf 3 )ppy) 2 (dtbbpy)pf 6 white LED DMS u(dtbbpy) 3 2PF 6 white LED DMS u(bpz) 3 2PF 6 white LED DMS r(ppy) 3 blue LED DMS r(ppy) 3 blue LED [ a] Determined by 1 -M analysis using 1,1,2,2-tetrachloroethane as an internal standard. 44

45 Substrate Scope (1) r(ppy) 3 (2 mol%), (10 mol%) + (1.1 eq.) Li t Bu (1.5 eq.), DMS (0.25 M) blue LED, degassed, 18 h r r(ppy) 3 79% 71% 73% 68% CF 3 67% 56% 51% 73% 54% 93% 61% 89% 45

46 Substrate Scope (2) r(ppy) 3 (2 mol%), (10 mol%) (1.1 eq.) Li t Bu (1.5 eq.), DMS (0.25 M) blue LED, degassed, 18 h r r(ppy) 3 t Bu Br 71% 66% 71% 70% 46% 44%.. 14% 24% 27% 46

47 Control Experiments r(ppy) 3 (2 mol%), (10 mol%) + (1.1 eq.) Li t Bu (1.5 eq.), DMS (0.25 M) blue LED, degassed, 18 h r r(ppy) 3 entry r(ppy) 3 blue LED yield (%) [a] [a] Determined by 1 -M analysis using 1,1,2,2-tetrachloroethane as an internal standard. 47

48 chanistic Study r(ppy) 3 (2 mol%), (10 mol%) + (1.1 eq.) Li t Bu (1.5 eq.), DMS (0.25 M) blue LED, degassed, 18 h r r(ppy) 3 q Stern Volmer Plot Study fac-r(ppy) 3 solutions ( mm in DMS) were excited at 320 nm and the emission intensity at 518 nm was observed. 0 / Carbazole [M] 0 / phenylcarbazole [M] 0 / odobenzene [M] 0 / Copper() odide [M] 48

49 Proposed chanisms blue LED r oto Sensitization r * Li Sen* Li CBZ 2 C Copper CBZ 2 B Proposed chanism A * CBZ CBZ 2 D CBZ Ligand Exchange r(ppy) 3 (2 mol%), (10 mol%) + (1.1 eq.) Li t Bu (1.5 eq.), DMS (0.25 M) blue LED, degassed, 18 h (= CBZ ) p Similar to Fu s mechanism p otocatalyst facilitates the p photosensitization process. r r(ppy) 3 p otocatalyst facilitates the p single-electron redox process. + r blue LED r otoredox r * Li SET CBZ 2 D Copper CBZ 2 B CBZ 2 J CBZ CBZ Proposed chanism B eductive Elimination Ligand Exchange (= CBZ ) 49

50 Proposed chanisms blue LED r oto Sensitization r * Li Sen* Li CBZ 2 C Copper CBZ 2 B Proposed chanism A * CBZ 2 D CBZ CBZ Ligand Exchange r(ppy) 3 (2 mol%), (10 mol%) + (1.1 eq.) Li t Bu (1.5 eq.), DMS (0.25 M) blue LED, degassed, 18 h (= CBZ ) p Similar to Fu s mechanism p otocatalyst facilitates the p photosensitization process. r r(ppy) 3 p otocatalyst facilitates the p single-electron redox process. + r blue LED SET r otoredox r * Li SET CBZ 2 D Copper CBZ 2 B CBZ 2 J CBZ CBZ Proposed chanism B eductive Elimination Ligand Exchange (= CBZ ) 50

51 Summary of Master s esearch 1. Visible-Light-diated Chan Lam Coupling eaction B() 2 oto Copper 1 2 edox Cat. Cat. 21 examples, 42% quant. W.-J. Yoo, T. Tsukamoto, S. Kobayashi, Angew. Chem. nt. Ed. 2015, 54, Visible-Light-diated C Ullmann-type Coupling eaction + oto edox Cat. Copper Cat. 19 examples, 44 93% W.-J. Yoo, T. Tsukamoto, S. Kobayashi, rg. Lett. 2015, 17,

52 Thank you for your attention! 52

53 Questions 1. Please provide the product in the reaction below. u(bpy) 3 (BF 4 ) 2 (cat.) antzch ester, i PrEt 2 DCM, blue LED, rt DBU DCM, rt A 2+ same photocatalysis u u(bpy)

54 Questions 2. n which quenching cycle does the following reaction take place? (x. or ed.) Please also rationalize the results of substrate scope. C + 2 (1.5 eq.) u(phen) 3 2 (1 mol%) DMS, 2, 32 ºC 36 h u(phen) 3 2 t Bu C 2 Et 79% 72% 61% trace trace 1.26 V u e e xidative Quenching Cycle 0.87 V u visible light u * eductive Quenching 1.36 V e Cycle e 0.82 V u e supported steps e 2 : V : 0.92 V 54

55 Questions 3. Please close the nickel catalysis filling in blanks A E. Be sure to show oxidation state of the metal species. 1 2 Si (1.2 eq.) 2 Et 3 + X u(bpy) 3 (PF 6 ) 2 (2 mol%) i 2 dme (5 mol%) dtbbpy (5 mol%) DMF, visible light rt, 16 h 1 2 u u(bpy) A C B D E 55

56 Questions 1. Please provide the product in the reaction below. = F D. S. Mu ller,. L. Untiedt, A. P. Dieskau, G. L. Lackner, L. E. verman, J. Am. Chem. Soc. 2015, 137,

57 Questions 2. n which quenching cycle does the following reaction take place? (x. or ed.) Please also rationalize the results of substrate scope. C + 2 (1.5 eq.) u(phen) 3 2 (1 mol%) DMS, 2, 32 ºC 36 h u(phen) 3 2 J. Liu, Q. Liu,. Yi, C. Qin,. Bai, X. Qi, Y. Lan, A. Lei, Angew. Chem. nt. Ed. 2014, 53,

58 Questions 3. Please close the nickel catalysis filling in blanks A E. Be sure to show oxidation state of the metal species. 1 2 Si Et 3 + X u(bpy) 3 (PF 6 ) 2 (2 mol%) i 2 dme (5 mol%) dtbbpy (5 mol%) DMF, visible light 2 rt, 16 h (1.2 eq.) M. Jouffroy, D.. Primer, G. A. Molander, J. Am. Chem. Soc. 2015, ASAP. 1 2 u u(bpy)

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