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Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu]...

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1 Catalytic Dipolar Cycloadditions: Adventures with Copper, Ruthenium, and Rhodium Valery V. Fokin Associate Professor The Scripps Research Institute [email protected] http://www.scripps.edu/chem/fokin Meet the Players (H,R 2 ) R 1 N N N R 3 O N R 3 R 1 N N R 3 R 1 R 4 H N SO 2 R 3 R 1 O N N SO 2 R 3 R 1 R 4 R 1 N N N R 3 R 1 R 2 N N N R 3 R 1 O N R 3 R 2 O N R 3 R 1 R 1 HN N R 3 Cl R 3 N 3 HO N R 3 Cl R 3 SO 2 N 3 R 3 N 3 HO N R 3 Cl a. R 3 SO 2 N 3 R 4 N R 4 [Ru] [Cu] b. [Rh]
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Page 1: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

1

Catalytic Dipolar Cycloadditions:Adventures with Copper, Ruthenium, and Rhodium

Valery V. FokinAssociate Professor

The Scripps Research Institute

[email protected] http://www.scripps.edu/chem/fokin

Meet the Players

(H,R2)R1

NN

NR3

O NR3

R1

N NR3

R1

R4

HN

SO2R3R1O

NN SO2R3

R1

R4

R1

NN

NR3

R1R2

NN

NR3

R1

O NR3

R2

O NR3 R1

R1

HN N

R3Cl

R3 N3 HO N

R3Cl

R3SO2N3

R3 N3HO N

R3Cl

a. R3SO2N3

R4

NR4

[Ru]

[Cu]b.

[Rh]

Page 2: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

2

Organic Azides: Reactivity

• Very energetic

• Yet most are stable and can be handled safely if simple precautions are observed

• Virtually inert to most other functionalities (certainly bio-orthogonal)

Organic Azides: Reactivity

• Very energetic

• Yet most are stable and can be handled safely if simple precautions are observed

• Virtually inert to most other functionalities (certainly bio-orthogonal)

Page 3: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

3

Organic Azides: Reactivity

• Very energetic

• Yet most are stable and can be handled safely if simple precautions are observed

• Virtually inert to most other functionalities (certainly bio-orthogonal)

NNN

RNu

δ+δ−

M, E+

Organic Azides: Making Connections

The Modified Staudinger Ligation

Saxon E., Bertozzi C.R. Cell Surface Engineering by a Modified Staudinger Reaction.

Science 2000, 287, 2007.

Page 4: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

4

Organic Azides: Making Connections

Kolb H.C., Finn M.G., Sharpless K.B. Click chemistry: Diverse chemical function from a few good reactions.

Angew. Chem. Int. Ed. 2001, 40, 2004.

“Click chemistry ideals are beautifully represented among cycloaddition reactions involving heteroatoms … especially 1,3-dipolar cycloadditions.

OH

N3

18

CN

Cl

OH

NNN

CN19

SN3

N3 MeO2C CO2Me SN

NNN

N N

MeO2C

MeO2C

CO2Me

CO2Metoluene, 95°C, 5h90%

16 17

H2O, reflux85%

Organic Azides: Making Connections

“Click chemistry ideals are beautifully represented among cycloaddition reactions involving heteroatoms … especially 1,3-dipolar cycloadditions.

OH

N3

18

CN

Cl

OH

NNN

CN19

SN3

N3 MeO2C CO2Me SN

NNN

N N

MeO2C

MeO2C

CO2Me

CO2Metoluene, 95°C, 5h90%

16 17

H2O, reflux85%

However, the desired triazole-forming cycloaddition requires elevated temperatures or highly activated dipolarophiles, and usually results in a

mixture of the 1,4- and 1,5-regioisomers.

Page 5: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

5

Azide-Alkyne Cycloaddition: Synthesis of 1,2,3-Triazoles

A. Michael, J. Prakt Chem. 1893, 48, 94.

EtOOC

N N N NN

N

COOEtCOOEt EtOOC

• Both are energetic, but sufficiently stable• Chemically inert to most other functionalities• React irreversibly forming 1,2,3-triazoles (ΔH = - 55 to -65 kcal/mol)

NN

N NN

N

Azide – Alkyne Cycloaddition:Making Connections

Page 6: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

6

NN

N NN

N

• Both are energetic, but sufficiently stable• Chemically inert to most other functionalities• React irreversibly forming 1,2,3-triazoles (ΔH = - 55 to -65 kcal/mol)

BUT very slowly and not regioselectively

Azide – Alkyne Cycloaddition:Making Connections

1,2,3-Triazoles

• Very stable to oxidation, reduction, and hydrolysis • High dipoles (ca. 4.7 – 5.2 Debye)• Weakly basic (N-2 and N-3 are H-bond acceptors)• Favorable metabolism and toxicology profiles

Page 7: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

7

Properties of 1,2,3-Triazoles

• Weakly basic hydrogen bond acceptors (at N2, N3)

• Much less basic than next member in the series

pKBH+ = 1.2pKa = 9.3

pKBH+ = 0 pKBH+ = 1 pKBH+ = 5.2 pKBH+ = 7 pKBH+ = 9.3

pKBH+ = 1.2pKa = 9.3

pKBH+ = 3.6

• Stable to severe reductive and oxidative conditions

Properties of 1,2,3-Triazoles

Page 8: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

8

• Two launched drugs and a number of compounds under investigation contain 1,2,3-triazoles

Tazobactamß-lactamase inhibitor

Substance P antagonist*Currently under investigation by Merck

RufinamideAnti-epileptic

131 MDDR hits on this general fragment

1,2,3-Triazoles

Organic Azides: Reactivity

NNN

RNu

δ+δ−

M, E+

Page 9: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

9

Metal Acetylides: Reactivity

G.S. Akimova, V.N. Chistokletov, A.A. Petrov, Zh.Obsh. Khim. 1965, 1, 2077.G.S. Akimova, V.N. Chistokletov, A.A. Petrov, Zh. Org. Khim. 1967, 3, 2241.

[M] = Li, Mg

Copper(I) Acetylides: Reactivity

C. Glaser Ber. Dtsch. Chem. Ges. 1869, 2, 422.

CuHNH4OH

CuCl

NH4OH

O2

CuCH3COOH

Δ +

F. Straus Justus Liebigs Ann. Chem. 1905, 190.

HBr

1. CuCl, NH2OH•HCl, EtNH2

2.

Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061.

Page 10: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

10

[Cu]

Cu

CuCu

Cu

Cu

Cu

Structure of Copper(I) Acetylides

[Cu]

Structure of Copper(I) Acetylides

Cu

CuCu

Cu

Cu

Cu

Cu

Cu

Cu

Cu

CuCu

Cu

Cu

Cu

CuCu

Cu

Cu

Cu

Page 11: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

11

In situ Generation of ReactiveCopper(I) Acetylides

R HCu(II), Ascorbate

H2OR [Cu]

Page 12: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

12

CuAAC:

Copper-Catalyzed Azide-Alkyne Cycloaddition

Not “click chemistry” and was not discovered when the 2001 Angewandte “Click Chemistry”paper was published.

Surely a click reaction, but not click chemistry!

N

NNHO

O

O

PhHO

O

N

NN

O PhCuSO4 • 5H2O, 1 mol%

sodium ascorbate, 5 mol%

H2O, r.t., 6 h 88%

NN

NNH

N NN

NH

NH2

HN

NN

N N

N

NN

NH

NH2

H2N

CuSO4 � 5H2O, 1 mol%sodium ascorbate, 5 mol%

H2O/tBuOH, 4 : 1, r.t., 2 h

88%

CuAAC: Simple, Reliable, Tolerant

Page 13: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

13

N NN

O NH

O COOH

HNO

HOOC

NNN

HN

O

COOH

O

NHO

H3COOCNH

HN

COOHO

NNN

O O

HN COOCH3

NH

HNCOOCH3

OO

NNN

O

HN

OCOOH

H3COOC

HOOCHN

NH

O

O

O

HNNH

COOCH3O

COOCH3

O

NNN

NN

N OHNAcHO

O

H3COOCS

NH

N NN O N

O

HNOH3COOC

COOH

S

H3COOC SHN

N

O

NN

ONH

OHOOC

2, 90% 1, 96%

4, 72%

8, 90%

6, 93%5, 84%

7, 93%

3, >99%

CuAAC: Hydrolysis-Stable Amide Bond Surrogate

O

H

H H

OH H

NHN

O

OO

OH

N3

O

H

H H

OHN

NN

NHN

O

O

O

OH

5% CuSO410% Sodium ascorbate

Dioxane/H2O45 oC, 8 h

6 grams, 90%

CuAAC: “Fusing” complex molecules

Page 14: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

14

DendrimersDendrimers

Complete control of size and shapeComplete control of size and shape

Chemically addressable surfaceChemically addressable surface

Multivalent, polyfunctionalMultivalent, polyfunctional

O

O

NN

N

N NN

R

R

O

O

NN

N

N NN

O

O

NN

N

N NN

R

R

OO

NNNN

NN

R R

OO

NNNN

NN

OO

NNNN

NN

R R

O

O

NN

N

NN N

OO

NNNN

NN

R R

OO

NNNN

NN

OO

NNNN

NN

R R

O

O

NN

N

N NN

R

R

O

O

NN

N

N NN

O

O

NN

N

N NN

R

R

O

O NNN

NN

N

O

O

NN N

NNN

R

R

O

O

NN N

NNN

O

O

NN N

NNN

R

R

O

O

NN N

NNN

R

R

O

O

NN N

NNN

O

O

NN N

NNN

R

R

O

O

NN N

NNN

O

O

NN N

NNN

O

NN N

1716

NN

NN

OO

OO

N N

N OO

O

NN

O

O

OH

HOH

H

O

OO

O

OCl

NO

Cl

Cl

S OO

N

1

2

3

4 5 6

N3

N3 MeOO

N3

9

N3HO

8

N3HO

O

7

NN3tBuO

O

H

CuAAC: Synthesis of Dendrimers

Page 15: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

15

• ca. quantitative yield for each step of the reaction sequence

• only stoichiometric amounts of reagents

• no byproducts: no chromatography up to the 4th

generation

Wu, P. et al. Angew. Chem. Int. Ed. 2004, 43, 3928.

CuAAC: Synthesis of Dendrimers

O

OO

OO

O

O

OOO

OHOH

O

HOHO

OO

O

OHO

HO

OHO

HO

O

OO

O

O

OOO

OHOH

O

HOHO

OO

O

OHO

HO

OHO

HO

CuAAC: Polyfunctional Dendritic Probes

Page 16: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

16

NNN

O

O O

OO

O

NHO

O

O

N

NN

N

NH

O OO

N

NN

N

O

OO

OO

O

O

OOO

OHOH

O

HOHO

OO

O

OHO

HO

OHO

HO

O

OO

O

O

OOO

OHOH

O

HOHO

OO

O

OHO

HO

OHO

HO

CuAAC: Polyfunctional Dendritic Probes

NNN

O

O O

OO

O

NHO

O

O

N

NN

N

NH

O OO

N

NN

N

O

OO

OO

O

O

OOO

OO

O

OO

OO

O

OO

O

OO

O

O

O

O

OO

OO O

O

OO

O

O

OOO

OO

O

OO

OO

O

OO

O

OO

O

O

O

O

OO

OO O

CuAAC: Polyfunctional Dendritic Probes

Page 17: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

17

NNN

O

O O

OO

O

NHO

O

O

N

NN

N

NH

O OO

N

NN

N

O

OO

OO

O

O

OOO

OO

O

OO

OO

O

OO

O

OO

O

O

O

O

OO

OO O

OHO

HOHO

HO

O NN

N

OOH

HOHO

HO

O NN N

OOHHO

HO

HO

ON

N N

OOHHO

HO

HO

O

NN N

OOHHO

HO

HO

O

NN N

OOH

HOHO

HO

O

NN N

OOH

HOHO

HO

O

NNN

OOH

HOHO

HO

O

NN

N

O

OO

O

O

OOO

OO

O

OO

OO

O

OO

O

OO

O

O

O

O

OO

OO O

OHO

HOHO

HO

O NN

N

OOH

HOHO

HO

O NN N

OOHHO

HO

HO

ON

N N

OOHHO

HO

HO

O

NN N

OOHHO

HO

HO

O

NN N

OHHO

HO

HO

O

NN N

OOH

HOHO

HO

O

NN N

OOH

HOHO

HO

O

NN

N

CuAAC: Polyfunctional Dendritic Probes

NNN

O

O O

OO

O

NHO

O

O

N

NN

N

NH

O OO

N

NN

N

O

OO

OO

O

O

OOO

OO

O

OO

OO

O

OO

O

OO

O

O

O

O

OO

OO O

OHO

HOHO

HO

O NN

N

OOH

HOHO

HO

O NN N

OOHHO

HO

HO

ON

N N

OOHHO

HO

HO

O

NN N

OOHHO

HO

HO

O

NN N

OOH

HOHO

HO

O

NN N

OOH

HOHO

HO

O

NNN

OOH

HOHO

HO

O

NN

N

O

OO

O

O

OOO

OO

O

OO

OO

O

OO

O

OO

O

O

O

O

OO

OO O

OHO

HOHO

HO

O NN

N

OOH

HOHO

HO

O NN N

OOHHO

HO

HO

ON

N N

OOHHO

HO

HO

O

NN N

OOHHO

HO

HO

O

NN N

OHHO

HO

HO

O

NN N

OOH

HOHO

HO

O

NN N

OOH

HOHO

HO

O

NN

N

P. Wu, M. Malkoch, J.N. Hunt, R. Vestberg, E. Kaltgrad, M.G. Finn, V.V. Fokin, K.B. Sharpless, and C.J. Hawker, Chem. Comm. 2005, 5775-5777

240-fold more potentthan mannose inhemagglutination

CuAAC: Polyfunctional Dendritic Probes

Page 18: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

18

CuAAC: One Pot Synthesis of 1,2,3-Triazoles

OPh

Cl

NNN

PhO

CuSO4 • 5H2O, 1 mol%sodium ascorbate, 5 mol%

H2O/DMSO, 10 : 1, 60 oC, 12 h

96%

NaN3 3 eq.

Cl

N NN

OPh

Feldman A.K., Colasson B., Fokin V.V. Org. Lett. 2004, 6, 3897.

R Br NaN3Cu(0), CuSO4, MW

tBuOH, H2O, 10-15 min125 oC

NN

N

R1

R1

H

R

CuAAC: One Pot Synthesis of 1,2,3-Triazoles

P.Appukkuttan, W.Dehaen, V.V. Fokin, E. Van der Eycken Org. Lett. 2004, 6, 4223.

Page 19: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

19

NN

N

Ph HCN

NN

N

Ph HO

O

O

NN

N

Ph

Me

HN

NN

HHO

84% 91%

89% 81%

R Br NaN3Cu(0), CuSO4, MW

tBuOH, H2O, 10-15 min125 oC

NN

N

R1

R1

H

R

CuAAC: One Pot Synthesis of Triazoles

P.Appukkuttan, W.Dehaen, V.V. Fokin, E. Van der Eycken Org. Lett. 2004, 6, 4223.

CuAAC: a Closer Look at the Catalyst

Cu(II)

Cu(I)

Cu(0)

Oxidation Disproportionation

Cu+ + 1e- Cu0 Eo = 0.52 V

Cu2+ + 1e- Cu+ Eo = 0.16 V

Cu+ + Cu+ Cu0 + Cu2+ K ~ 106

Page 20: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

20

Ph H

HO

N

OH

N

NN PhNN

Ph

+

Cu0 (on a stirbar)

H2O/t-BuOH, 2 : 1

RT, 24 hrs

MW, 150 oC, 5 min

99%

N

HO

N

OH

N N

NN

CuAAC: Copper Metal Catalyzes the Reaction

Rx N3

Ry

+H

Rx

N3

Rx

N3

Ry

H

Ry

H

24 - 48 hDMSO, water, tBuOH ...

RxN

NN

H

Ry Rx

NN

NH

Ry

RxN

NN

H

Ry

Page 21: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

21

Azide: 100 μL of 20 mmol solution in tBuOH (final conc. 5 mM)

Alkyne: 100 μL of 24 mmol solution in tBuOH (final conc. 6 mM)

CuSO4 200 μL of 0.05 mmol aq. solution (final conc. 0.025 mM)

Added to a small piece of copper turning in a sealed mictrotiter plate and shaken at 40 ºC for 36 hrs. Completion determined by disappearance of azide using LCMS.

Reactions initially diluted to 0.5 mM with DMSO, then to 10 μM with aq. buffer into 96 well plates

Analysed for HIV-1 protease inhibition using a fluorescence assay

Active compounds further diluted and re-assayed

CuAAC: HIV-1 Protease InhibitorsSynthesis of the screening libraries

R2

HN

N3

R3

O

R1 1.1 eq.alkyne, 5 mol % CuSO4, Cu wire,1:1 tBuOH/H20, 50 ºC, 36 hrs

R2

HN

N

R3

O

R1

NN

R4

+ R4

R1 = Various, R2, R3 = iBu, Bn, R4 = Various

4 azides 70 alkynes280 triazoles

Without the triazole ring all compounds were essentially inactive

Further functionalisation of the triazole ring at the 5 position is OK and leads to more potent analogs

PhPh

HN

HN

O

O

O

N

PhPh

HN

HN

O

O

O

N NN

PhPh

HN

HN

O

O

NN

HO

PhPh

HN

N

O

O

NN

N N

1) 2.2 eq. n-BuLi, -78 ºC, THF2) Electrophile

PhPh

HN

N

O

O

NN

N N

E

E = HTMSCH2OHCH(CH3)OH

IC50 = 134 nM10 µM56 nM43 nM

CuAAC: HIV-1 Protease InhibitorsFunctionalization of the triazole

Whiting M., Tripp J., Lin Y.-C., Lindstrom W., Olson A.J., Sharpless K.B., Elder J.H., Fokin V.V.J. Med. Chem. 2006, 49, 7697.

Page 22: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

22

PhPh

HN

N

O

O

NN

N N

ClOH

Ki = 8 nM

Ph PhHN

N

O

O

NN

N N

ClOH

Ki = 20 nM

CuAAC: HIV-1 Protease InhibitorsFunctionalization of the triazole

Whiting M., Tripp J., Lin Y.-C., Lindstrom W., Olson A.J., Sharpless K.B., Elder J.H., Fokin V.V.J. Med. Chem. 2006, 49, 7697.

CuAAC: a Closer Look at the Catalyst

Cu(II)

Cu(I)

Cu(0)

Oxidation Disproportionation

Cu+ + 1e- Cu0 Eo = 0.52 V

Cu2+ + 1e- Cu+ Eo = 0.16 V

Cu+ + Cu+ Cu0 + Cu2+ K ~ 106

Page 23: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

23

N

"Cu"

N

N

N

Ph

NN

N

PhN N

NPh

CuAAC: Accelerating/Stabilizing Ligand,TBTA

NN

NN

N NN

N

NN

Ph

PhPh

85%

T.R. Chan et al, Org. Lett. 2004, 6, 2853.

Cu+ + 1e- Cu0 Eo = 0.52 V

Cu2+ + 1e- Cu+ Eo = 0.16 V

Cu2+ + 1e- Cu+ Eo ~ 0.45VTBTA

CuAAC: Resin-Supported TBTA

TBTATris(BenzylTriazolyl)Amine

TG-TBTATentaGel resin

• Solution-phase ligand capable of supporting copper(I) catalysis

• Avoids the use of reducing agents and large loeading of copper

• Solid-phase catalyst facilitates separation of copper and ligand from products

• TentaGel resin exhibits excellent swelling properties in a wide variety of solvents

N

NNN

NN

NN

N N

Bn

Bn

Bn N

NNN

NN

NN

N N

Bn

Bn

Linker

T.R. Chan, V.V. Fokin, QSAR and Comb. Sc. 2007, 1274.

Page 24: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

24

Copper wash

(e.g. Cu(MeCN)4PF6, CH2Cl2)

NHTBTA

O

NHTBTA

OCuPF6

• Copper loading determined by leaching resin with pyridine (24 h), and the resulting solution analyzed by ICP-AA

• Copper loading measured to be 0.19 mmol/g

• loading is quantitative (TBTA:Cu stoichiometry determined to be 1.01:1)

T.R. Chan, V.V. Fokin, QSAR and Comb. Sc. 2007, 1274.

CuAAC: Resin-Supported TBTA

Reactions performed at 50ºC, at 0.10 M concentration in MeOH with 3-4 mol% of catalyst (4 mg), purity determined by HPLC.

CuAAC: Resin-Supported TBTA

Page 25: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

25

CuLx•R1

N NN R2

NN

N R2

CuLxR1

CuLxR1N

NNR2

R1 CuLx

NNN R2

R1 H

NN

N R2

HR1[CuLx]

H+H+

Step A

Step B

Step C

Step D

Step E

CuAAC: Not a Concerted Process

F. Himo et al. J. Am. Chem. Soc. 2005, 127, 210-216

DFT CalculationsUncatalyzed cycloaddition Ea = 25.4-26 kcal/molCopper-catalyzed cycloaddition Ea = 14.5 kcal/mol

KineticsRate = [Azide]1[Alkyne]1.3-1.6[Cu]2

Ea = 11 kcal/mol

F. Himo et al. J. Am. Chem. Soc. 2005, 127, 210-216V. Rodionov et al. Angew. Chem. Int. Ed. 2005, 44, 2210-15

M. Ahlquist et al. Organometallics 2007, 26, 4389-93

CuAAC: Key Mechanistic Parameters

[Cu]CuLR1

NNN R2

CuL•R1

N NN R2

[Cu]

Page 26: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

26

CuAAC: An Isolated Example or a New Reactivity Manifold of Cu acetylides ?

CuAAC: An Isolated Example or a New Reactivity Manifold of Cu acetylides ?

Page 27: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

27

R1 H

O

1. H2NOH·HCl, NaOH

t-BuOH:H2O (1:1)

2. TsNClNa·3H2O

R1

ON3.Cu0/CuSO4 (cat.) R2

R2

Copper-Catalyzed Synthesis of Isoxazoles

Hannsen, T., Wu, P., Fokin, V.V. J. Org. Chem. 2005, 70, 7761.

R1 H

O

1. H2NOH·HCl, NaOH

t-BuOH:H2O (1:1)

2. TsNClNa·3H2O

R1

ON3.Cu0/CuSO4 (cat.) R2

R2

R1 H

NR1 N

R2H2NOH

TsNClNa·3H2OO

Cu0/CuSO4 (cat.)

OH

Copper-Catalyzed Synthesis of Isoxazoles

Hannsen, T., Wu, P., Fokin, V.V. J. Org. Chem. 2005, 70, 7761.

Page 28: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

28

ON O

ONON

70%

73%72%

ON

61%

OO

OH

H

H

ON

MeO OH

H

66%

ON

OH

76%

Copper-Catalyzed Synthesis of Isoxazoles

Hannsen, T., Wu, P., Fokin, V.V. J. Org. Chem. 2005, 70, 7761.

CuSO4Ascorbic acid

NaOAc 45 oC, 4-8hNH2

i) 1.0 equiv. NaNO2 2.0 equiv. HBr

ii) 1.0 equiv.

H2O+(Methanol or MeCN)

NHN

ClEtO

O

R2

NN R2

EtOO

1.0 equiv.

O

Cl

O

OEt

R1 = H, Cl, Br, NO2, SO2NH2

R1R1 R1

Copper-Catalyzed Synthesis of Pyrazoles

NN

EtO2C

Br

81%

Cl

NN

EtO2C

Ph

SO2NH2

79%

NN

EtO2C

Ph

83%

CN

X. Wang, V.V. Fokin 2008, unpublished

Page 29: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

29

CuLx•R1

N NN R2

NN

N R2

CuLxR1

CuLxR1N

NNR2

R1 CuLx

NNN R2

R1 H

NN

N R2

HR1[CuLx]

H+H+

Step A

Step B

Step C

Step D

Step E

CuAAC: Not a Concerted Process

F. Himo et al. J. Am. Chem. Soc. 2005, 127, 210.

CuLxR1N

NNR2

M

NNN

R2

H

R1

CuLxR1

NNN R2N N

N R2

R1

N NN R2

R1M

NNN

H

R1

R2

Can other metals do the trick?

Page 30: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

30

RuAAC: the 1,5-Regioisomer

Zhang, L. et al. J. Am. Chem. Soc. 2005, 127:15998.

R1 HNN

N R2

H+Step A

Step BStep C

Step D

RuCl NN

N

R2

R1

RuCl NN

N

R2

R1

RuCl LL

NNN R2

RuCl N

NN

R2

R1

R1

RuAAC: Mechanism

Boren, B.C. et al, J. Am. Chem. Soc. 2008, 8923.

Page 31: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

31

RuAAC: Terminal Alkynes

93%

N3

N

NN

NH2

N

NN

H2N

OH HO

83%

N3

Cp*RuCl(PPh3)2, 2 mol%

Dioxane, 60 oC, 1h

Cp*RuCl(PPh3)2, 2 mol%

Dioxane, 80 oC, 18h

Boren, B.C. et al, J. Am. Chem. Soc. 2008, 8923.

very stable,catalytically inactive

RuAAC: Catalyst Deactivation

Hursthouse J. Chem. Soc. Dalton Trans. 1996, 3771

RuClL

L

N N NR2

RuClN

NN

N R2

, 3 eq

r.t., toluene R2RuCl

NR2

N N NR2

Ru

N N

NN

Boren, B.C. et al, J. Am. Chem. Soc. 2008, 8923.

Page 32: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

32

RuAAC: Terminal Alkynes/Aryl Azides

L.K. Rasmussen, B.C. Boren, V.V. Fokin, Org. Lett. 2007, 5337.

O O

OH

N3OH

OH

OH

OH NOH

HOOH

HO

NN

OH

75%

N3

N

NNH

O

N NN

N

N

NH

O

81%

NN

OO

N3N

N

OO

N NN

Cp*RuCl(PPh3)2, 2 mol%

Dioxane, 60 oC, 2h

90%

O O

Cp*RuCl(PPh3)2, 2 mol%

Dioxane, 60 oC, 8h

Cp*RuCl(PPh3)2, 2 mol%

Dioxane, 60 oC, 8h

RuAAC: Terminal Alkynes

Boren, B.C. et al, J. Am. Chem. Soc. 2008, 8923.

Page 33: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

33

RuAAC: Internal Alkynes

PhN3 Ph

N

NN

[Ru], 4 mol%

r.t., toluene, 4h

83%, 0.48 g

+Ph

Ph

PhN

NN

76%, 0 42g

+ [Ru], 4 mol%

r.t., toluene, 4h

2.4 mmol

PhN3

2 mmol

2.4 mmol

2 mmol

[Ru] = RuCl

RuCl

Ph3PPh3P

OR

Boren, B.C. et al, J. Am. Chem. Soc. 2008, 8923.

RuAAC: Internal Alkynes

PhN3

PhN

NN

HOHO

83%

+ Ph

Ph

EtON3

EtON

NN

HOHO

72%

+

O

OH

OHO

Cp*RuCl(COD), 2 mol%RT, 1,2-DCE, 2h

Cp*RuCl(COD), 2 mol%RT, 1,2-DCE, 2h

Boren, B.C. et al, J. Am. Chem. Soc. 2008, 8923.

Page 34: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

34

RuAAC: Internal Alkynes

PhOH

N3 NNN

Ph

OH

Ph NO

O

N3

NN N

PhN

O

O

Cp*RuCl(COD), 2 mol%RT, 1,2-DCE, 2h

+

+ Cp*RuCl(COD), 2 mol%RT, 1,2-DCE, 30 min

93%

95%

Boren, B.C. et al, J. Am. Chem. Soc. 2008, 8923.

Ru-Catalyzed Synthesis of Isoxazoles

Grecian, S., Fokin, V.V. Angew. Chem. Int. Ed. 2008, in press.

Cl

NOH

+

NO

Cl

PhCl

Cp*RuCl(COD), 2 mol%

NO

O

MeMe

Ac

Cl

NOH

O

MeMeAc

+ Cp*RuCl(COD), 2 mol%

89%

93%

Et3N, 1.1 eq, 1,2-DCE, RT

Et3N, 1.1 eq, 1,2-DCE, RT

NO

OMeMe

AcCl

NOH

O

MeMeAc

+

21%

Page 35: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

35

Ru-Catalyzed Synthesis of Isoxazoles

Grecian, S., Fokin, V.V. Angew. Chem. Int. Ed. 2008, in press.

1,2,3-Triazoles are very stable, except ...

O. Dimroth, Lieb. Ann. 1909, 364, 183

NN

N Ar

Ar Li

N

RAr

LiN

Ar.Li

Ar

R. Raap, Can. J. Chem. 1971, 49, 1792-1798

Page 36: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

36

Ph[Cu]

SO2TolN

NN

NSO2Tol

Ph

N

N

[Cu]Ph

Ph

NSO2Tol

TolO2SNH

HPh

NNSO2TolN

NSO2TolPh

TolO2SN Ph

[Cu]

H+

- H+

-[Cu], -N2

Ph

NSO2Tol

[Cu]

-N2 H+, -[Cu]

Ph

H

NSO2Tol

Sulfonyl Azides – Mild Route to Keteneimines

CuAAC: Reactions of Keteneimines

Chang S. et al., JACS, 2005M. Cassidy, J. Raushel, V.V. FokinAngew. Chem. Int. Ed. 2005

M. Whiting, V.V. FokinAngew. Chem. Int. Ed. 2005

Page 37: Meet the Players...Chodkiewicz W., Cadiot P., Willemart A.:. Compt. Rend. 1957, 245, 2061. 10 [Cu] Cu Cu Cu Cu Cu Cu Structure of Copper(I) Acetylides [Cu] Structure of Copper(I) Acetylides

37

CuAAC: One Pot Synthesis of Azetidinimines

N

NSO2R'R

PhPhHR

SO2N3

Ph NPh

+

CuI, 10 mol%pyridine, 2 equiv

CH3CN, 0.5Mr.t., 16h

N

NSO2R'R

PhN

NSO2R'R

PhN

NSO2R'R

Ph

NF3C

Cl

81% 65%79%

M. Whiting, V.V. Fokin Angew. Chem. Int. Ed. 2005

• Mårten Ahlquist• Michael Cassidy• Timothy Chan• Stepan Chuprakov• Scott Grecian• Luke Green• Jason Hein• Tony Horneff• Jason Kwok

• Jarek Kalisiak• Larisa Krasnova• Ying-Chuan Lin• Suresh Pitram• Jessica Raushel• Jon Tripp• Mat Whiting• Timo Weide• Peng Wu

NIH (NIGMS)Pfizer, Inc.

The Skaggs Institutefor Chemical Biology

Prof. Guochen Jia (Hong Kong UST)Prof. Vladimir Gevorgyan (UIC)Prof. K. Barry Sharpless (TSRI)Prof. Craig J. Hawker (UCSB)


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