photoelectrochemistryin organic synthesis

Photoelectrochemistry in Organic Synthesis

Reporter :Gao Shiquan (高师泉）Supervisor: Prof. Zhang Junliang

2020-12-25

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1. Introduction1.1 Synthetic Organic Electrochemistry

1.2 Visible-Light Photoredox Catalysis

1.3 Photoelectrochemical Organic Synthesis

2. Photoelectrochemical Organic Synthesis 2.1 Electromediated Reaction with Photoredox Catalysis

2.1.1 Oxidation Reaction2.1.2 Reduction Reaction2.1.3 Redox Neutral Reaction

2.2 Electromediated Reaction involving Photo-induced Radical

2.3 Interfacial Photoelectrochemistry

3. Summary and Prospection

2

Contents









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Contents

IntroductionSynthetic Organic Electrochemistry

4

undivided cell divided cell (“H” cell)

workingelectrode

counterelectrode

power

constant current (cc)constant voltage (cv)

reference electrode

Electrochemical Cells

Modes of Operation

S. R. Waldvogel et al. Chem. Sci., 2020, 11, 12386.


5

low surface area(graphite Pt)

high surface area(Ni foam RVC)

sacrificial anode (Zn Mg Al)

THF DCM Acetone Methanol MeCN DMA H2O8 9 21 33 38 38 80

more resistance less resistanceε

Electrodes

Solution

P. S. Baran et al. Acc. Chem. Res. 2020, 53, 72.

- -

+ 2

+

- -

-

n+

- -

-+

Redox-neutralReaction

OxidativeReaction

ReductiveReaction

6

Workingelectrode

Counterelectrode

Counterelectrode

Workingelectrode

Workingelectrode

Workingelectrode


R. D. Little et al. Chem. Soc. Rev., 2014, 43, 2492. 7


Mes-AcrIr[dFCF3ppy]2(bpy) Ru(bpy)3 4CzIPN Eosin Y

G. A. Molander et al. ACS Catal. 2017, 7, 2563. 8

Introduction

ReductiveReaction

OxidativeReaction

Redox NeutralReaction

Energy TransferReaction

Visible-Light Photoredox Catalysis

PC

*[PC]

PC-

Ox

Ox•-

sub

sub•+

PC

*[PC]

PC+

subb

suba

subb•-

suba•+

• energy constrained• energy losses• equivalent oxidizing or reducing agent

• low conductivity of organic solvents • unselective redox processes• limited mediators potential

The limits of PRCThe limits of SOE

9

IntroductionPhotoelectrochemical Organic Synthesis

High selectivity/energy efficiencyAtom efficient Large redox window

redox energyfrom

photoexcitation

redox energyfrom

electrochemistry

J. P. Barham et al. Angew. Chem. Int. Ed. 2020, 59, 2. 10


NH

S

CN

CN9,10-dicyanoanthracene

(DCA)

phenothiazine (PTZ)

PTZ

PTZ +

*PTZ

MO-1

MO-2

MO-3

HOMO-4

MO-1

MO-2

HOMO-3

SOMO-4

SOMO-1

MO-2

MO-3

HOMO-4

SOMO-1

HOMO-2

SOMO-2

HOMO-1

LUMO-2

HOMO-1

1

1

1

E = +0.70 V

E = 2.23 eV

Imax = 514, 772,864 nm

-e-

h

*E = 2.9 V

DCA

DCA

*DCA

Imax = 450, 480,510 nm

+e-

h

*E = -3.2 V

1

1

1

E = 2.43 eV

E = -0.82 V

E E

electromediatedphotoredox calatlyst (e-PRC)

SOMO-HOMO inversion SOMO-HOMO inversion

J.-C. Moutet, G. Reverdy. Tetrahedron Lett. 1979, 20, 2389. J.-C. Moutet, G. Reverdy. J. Chem. Soc. Chem. Commun. 1982, 654. 11


PhPh

Ph Ph

Ph

O

Ph Ph

Ph Ph

PTZ (6 mol%)LiClO4

Pt rotating disk voltammetry0.79 V vs SCE

Hg Lamp (<400 nm)MeCN

+

1:1.3 by HPLC

(DPE)NH

S

phenothiazine (PTZ)1 2

H2H+

e-

*TPPD•+

TPPD

TPPD•+

OH

OH OH O

Contents









12

13

Photoelectrochemical Organic Synthesis Electromediated Reaction with Photoredox Catalysis

B. Konig et al. Photochem. Photobiol. Sci., 2010, 9, 1367.B. Konig et al. Chem. Eur. J. 2008, 14, 1854.D. R. Carbery et al. Angew.Chem. Int.Ed. 2015, 54,8997.B. Konig et al. ChemCatChem. 2012, 4, 620.J. C. Gonzalez-Gomez et al. Organic Letters 2019 21 (5), 1368.

Flavin

B. Konig et al. Chem. Eur. J. 2008, 14, 1854.S. Lin et al. Angew. Chem. Int. Ed. 2020, 59, 409.


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1a: E ≈ 1.5 V1b: E > 1.9 VRFT*: E = 1.67 V

Fluorescence quenching of RFT with 1a Fluorescence quenching of RFT with 1b

S. Lin et al. Angew. Chem. Int. Ed. 2020, 59, 409.


15

13C NMR of (A) TU-1-O2 (B) white precipitate (C) TU-1

Fluorescence quenching of RFT with TU-2

S. Lin et al. Angew. Chem. Int. Ed. 2020, 59, 409. 16


OMe

Me

OMe

Me

1b (1 eq.), RFT (5 mol%)LiOTf (0.1 M CH3CN), H2O

C(+)/Pt(-), 2.5 Vblue LED, 22 °C, 1 h

OMe

Me

OMe

1b (1 eq.)RFT (5 mol%), TU-2 (10 mol%)

LiOTf (0.1 M CH3CN), H2OC(+)/Pt(-), 2.5 V

blue LED, 22 °C, 1 h

Me

Z:E = 6:1 71% recovered, Z:E = 10:1100% 1b recovered

75% recovered, Z:E = 1:100100% 1b recovered

Z:E = 6:1

S. Lin et al. Angew. Chem. Int. Ed. 2020, 59, 409. 17


N

N

NH

N O

O

OAc

AcOOAc

OAc

Me

Me

RFT

Selected Substrates

H2

H+RFT-H2

RFTRFT*

RFT•-H

e-

OHtBu OtBu

NH

S

NH

R R

N

S

NH

R R

S

NHR

RNS NR

NHR

OHtBu

OHtBu

H2S +

E 0.8 V

NH

S

NH

R R

PhS

O O

Me

O

75%

O

Me Me

H

MeO

Me H

Me

H

H HO

O

96% 89%88%

T. H. Lambert et al. Angew. Chem. Int. Ed. 2019, 58, 13318. 18


Selected Substrates

N N

CHO

N NN

N N

COOEt

Cl

Cl

Me

MeMe

Me

MeMe

Br

65% 42% 75% 71%

NN

COOEt

T. H. Lambert et al. J. Am. Chem. Soc. 2020, 142, 1698. 19


Selected Substrates

*TAC2+

N

N N

Me MeMe

Me Me

Me

*

SO2Ph HNN

CHO

NBr

O NO

CHO

MeO

SO2Ph

89%72%40%80%

O NN

CHO

+ +

H.-C. Xu et al. Angew. Chem. Int. Ed. 2019, 58,4592. 20


Selected Substrates

H2H+

e-

Mes-Acr•

*Mes-Acr+

Mes-Acr+

F3B Me

Me

Me

Me+ BF3

NH

Me

NH

Me

Me

Me

H+

Mes-Acr+ Mes-Acr•NH

Me

Me

2 mA

E = 2.06 VEp/2 = -1.19 V

Ep/2 = -0.57 V

Me

H.-C. Xu et al. Angew. Chem. Int. Ed. 2020, 59, 10626. 21


Selected Substrates

L. Ackermann. et al. Chem. Eur. J. 2020, 26, 3241. 22


Selected Substrates

Me Me

Me

CF3

79%with [Mes-Acr]ClO4

iPr

iPr

CF3

67%with [Ru(bpy)3](PF6)2

OMeCF3

MeO2C

71%with [Ru(bpy)3](PF6)2

SnBu

CF312

64% (1:2 = 14:1)with [Mes-Acr]ClO4

A.-W. Lei et al. J. Am. Chem. Soc. 2020, 142, 17693. 23


Selected Substrates

S. Lin et al. J. Am. Chem. Soc. 2020,142, 2087. 24


Selected Substrates

CN

CNDCA

DCA

*DCA•-

DCA•-

Cl

MeO

MeO

B2pin2Bpin

MeO

E = -3.2 V

Zn2+

E = -1.0 Ve-

T. H. Lambert et al. Angew. Chem. Int. Ed. 2020, 59, 658. 25


Selected Substrates

ONC

NC

Cl

ClO

DDQ

Cl

e-

*DDQ

DDQ•-

DDQ

F

Cl

Cl

F

NHN

CHOH+

Cl

Cl

F-

E = 3.18 V

FNN

CHO

FNN

CHO N N

CHO

E = 1.5 V

DDQ•-

DDQ


Electromediated Reaction involving Photo-induced RadicalPhotoelectrochemical Organic Synthesis

Selected Substrates



Selected Substrates

N

HCl (6 eq.)Et4NCl (0.3 eq.)C(+) Pt(-), 2 mAblue LED (10 W)

MeCN N

C(sp3)

+ H C(sp3)R1 R1

H

S. Stahl et al. Angew. Chem. Int. Ed. 2019, 58, 6385. 28


Selected Substrates

X.-L. Hu et al. Nat. Catal. 2019, 2, 366.

Interfacial Photoelectrochemistry

29

Photoelectrochemical Organic Synthesis

Selected Substrates

CB

VBh+

e-

photoanode(semiconductor)

h

e-

sub

sub•+

VB:valence bandCB:conduction bandh:hole conduction

H2H+

e-

OMeNHN

OMe

•-H+

OMe

•

OMe -e-

-H+NN

OMe

H H

HN

N N

N

N NH

E = 0.73 V

OMe

MeO CO2Me

N N

N

Cl

OOEt

O

Me Me

87%(P1:P2=3:1)

1

2

82%

N

NNOMe

77%o:p = 6:1

NNOMe

58%o:p = 14:1

Cl

C. P. Berlinguette et al. Nat. Commun. 2017, 8, 390. 30

Interfacial PhotoelectrochemistryPhotoelectrochemical Organic Synthesis

NO O

OH

(NHS)

Contents









31

Summary and Prospection

32

OxidativeNMe

Me

Me Me

ONC

NC

Cl

ClO

Reductive

HAT

4czIPN

4czIPN

TAC Mes-Acr

DDQ

DCA

RFT TAC

NN

Ru

N

N

NN

Ru(bpy)3

ONC

NC

Cl

ClO

DDQ

9-fluorenone

• Rigorous control experiments• Interelectrode ohmic drop• Mass transfer

Summary and Prospection

33

The limits of Photoelectrochemistry

a

b

c

d

pump

e-

reactants

products

a:borosilicate glass coverb:working electrode platewith groove channelsc:ion-exchange membraned:counter electrode plate

New reaction ?New mediator ?Chiral reaction ?

Thanks for your kind attention

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photoelectrochemistryin organic synthesis

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