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  • Organic Seminar

    Recent Advances in Ni Catalyzed Suzuki Coupling:

    Toward Green, Cheap and Environmentally Friendly Catalysis

    Chun Ho Lam

    2nd November, 2011

    1

  • The Palladium Coupling Reactions

    Ni0

    2

  • The Popularity of Cross Coupling Reaction

    Colacot, T.J. Platinum Metals Rev., 2011, 55, 8490. 3

  • Advantages of Suzuki Coupling Over Others

    The use of Boron Coupling Partner over others:

    Mild Reagent

    Relatively Non-Toxic

    Many Organoboronic acids are commercially available

    Tolerate a lot of functional groups

    Comparatively, Moderately Air Stable

    Rosen, B. M.; Quasdorf, K. W.; Wilson, D. A.; Zhang, N.; Resmerita, A.-M.;

    Garg, N. K.; Percec, V. Chem. Rev. 2011, 111, 13461416. 4

  • Leaving Group:

    Oxidative Addition

    Reactivity

    Ar-X: I >> Br > Cl

    The Research Focus on Suzuki Coupling:

    Using Suzuki Coupling as an Example:

    Ligand Metal Complex

    (In particular to the Ligand)

    Solubility

    Air Stability

    Reactivity

    Stereo Selectivity

    Boronic Partner:

    (R = H) Boronic Acid

    (R = Alkyl) Boronic Ester

    Coupling Group

    Aryl

    Allyl

    Alkyl

    Hetero

    Rosen, B. M.; Quasdorf, K. W.; Wilson, D. A.; Zhang, N.; Resmerita, A.-M.;

    Garg, N. K.; Percec, V. Chem. Rev. 2011, 111, 13461416. 5

  • Consideration on Group 10 Metals: Ni, Pd

    Why Nickel?

    Why not Nickel?

    USD mol-1 Abundance Est. Electronic Config. Possible Oxi. State

    Ni $1.20 84 mg / kg [Ar] 3d8 4s2 0, +2 (+1,+3)

    Pd $1,500 0.02 mg / kg [Kr] 4d10 (Not 4d8 5s2) 0, +2 (+1, +4)

    Cat. Loading Ligand Extra Ligand Loading Extraction

    Ni 5 10 mol% 1 4 equiv Always Difficult

    Pd 0.1 5 mol% 1 4 equiv Sometimes Moderate

    Rosen, B. M.; Quasdorf, K. W.; Wilson, D. A.; Zhang, N.; Resmerita, A.-M.;

    Garg, N. K.; Percec, V. Chem. Rev. 2011, 111, 13461416. 6

  • Common Leaving Groups in Suzuki Reaction

    Palladium Nickel

    Halides: -Cl, -Br, -I

    Enol/Phenol Derivatives : -OTf, -OMs, -OTs, -OP(O)(OR)2

    Esters: -OC(O)R

    Sulfamate: -OSO2NR2

    Carbamate:-OC(O)NR2

    Ether: -OR

    Jana, R.; Pathak, T. P.; Sigman, M. S. Chem. Rev. 2011, 111, 14171492. 7

    Common Leaving Group:

    Notes:

  • Seminar Outline

    Part 1

    Suzuki Cross Coupling of Aryl Carbamate and Aryl Sulfamate

    Ox. Addition Selectivity Towards the Guided Site

    Room Temperature Catalyzed Inactivated Electrophile

    Part 2

    Suzuki Cross Coupling of Aryl Ether

    Reductive Demethoyxlation in Aryl Ether

    Possible Application in non-synthetic area

    8

  • Suzuki Cross-Coupling of Aryl Carbamates

    Selected Examples:

    Sensitive to steric hindrance, and the substitution effect

    Quasdorf, K. W.; Antoft-Finch, A.; Liu, P.; Silberstein, A. L.; Komaromi, A.; Blackburn, T.;

    Ramgren, S. D.; Houk, K. N.; Snieckus, V.; Garg, N. K. J. Am. Chem. Soc. 2011, 133, 6352-6363. 9

  • Suzuki Cross-Coupling of Aryl Sulfamates

    Insensitive to EWG and EDG, and Steric

    Selected Examples:

    10 Quasdorf, K. W.; Antoft-Finch, A.; Liu, P.; Silberstein, A. L.; Komaromi, A.; Blackburn, T.;

    Ramgren, S. D.; Houk, K. N.; Snieckus, V.; Garg, N. K. J. Am. Chem. Soc. 2011, 133, 6352-6363.

  • Study of Oxidative Addition of Ni(PPh3)2

    Hammett Plot on Relative Rates of Ox. Addition:

    Foa, M.; Cassar, L. J. Chem. Soc.-Dalton Trans. 1975, 23, 2572-2576.

    The Experiment:

    The Purpose - See the Effect of Substitute

    EW

    11

  • DFT Analysis: Oxidative Addiction Mechanism

    12

    Carbamate:

    Sulfamate:

    5-Centered TS is more

    favorable vs. 3-Centered

    Sulfamate higher

    reactivity results in the

    more stable T.S.

    Phosphorus

    Nickel

    Oxygen

    Nitrogen

    Carbon

    Sulfur

    Hydrogen

    Quasdorf, K. W.; Antoft-Finch, A.; Liu, P.; Silberstein, A. L.; Komaromi, A.; Blackburn, T.;

    Ramgren, S. D.; Houk, K. N.; Snieckus, V.; Garg, N. K. J. Am. Chem. Soc. 2011, 133, 6352-6363.

    Cy Ligand

  • DFT Analysis: Selective Oxidation Addition

    Carbamate:

    Sulfamate:

    13 Quasdorf, K. W.; Antoft-Finch, A.; Liu, P.; Silberstein, A. L.; Komaromi, A.; Blackburn, T.;

    Ramgren, S. D.; Houk, K. N.; Snieckus, V.; Garg, N. K. J. Am. Chem. Soc. 2011, 133, 6352-6363.

    Phosphorus

    Nickel

    Oxygen

    Nitrogen

    Carbon

    Sulfur

    Hydrogen

    Ox. Addition

    Selectivity?

    Higher coordination => Lower T.S.

    Energy

    Coordination dictates the site where

    Ox. Addition occurs

    Interesting to see how Pd coordinate

    and its relative energetic.

  • Inertness Towards Palladium

    Quasdorf, K. W.; Antoft-Finch, A.; Liu, P.; Silberstein, A. L.; Komaromi, A.; Blackburn, T.;

    Ramgren, S. D.; Houk, K. N.; Snieckus, V.; Garg, N. K. J. Am. Chem. Soc. 2011, 133, 6352-6363. 14

    An strategic synthesis example:

  • Seminar Outline

    Part 1

    Suzuki Cross Coupling of Aryl Carbamate and Aryl Sulfamate

    Ox. Addition Selectivity Towards the Guided Site

    Room Temperature Catalyzed Inactivated Electrophile

    Part 2

    Suzuki Cross Coupling of Aryl Ether

    Reductive Demethoyxlation in Aryl Ether

    Possible Application in non-synthetic area

    15

  • Ni. Cat. Non-Aromatic sp3 Suzuki Coupling

    Selected Examples:

    EWG & EDG have

    minor effects

    Ester and OPiv are

    Vulnerable

    Selectively on -aliphatic pivalate

    Huang, K.; Li, G.; Huang, W.-P.; Yu, D.-G.; Shi, Z.-J. Chem. Commun. 2011, 47, 7224-7226. 16

  • Suggested Mechanism for the Catalytic Cycle

    Huang, K.; Li, G.; Huang, W.-P.; Yu, D.-G.; Shi, Z.-J. Chem. Commun. 2011, 47, 7224-7226. 17

  • Suggested Di-Oxygen Guided Insertion

    Selective Activation is dictated from stability of the T.S.

    Huang, K.; Li, G.; Huang, W.-P.; Yu, D.-G.; Shi, Z.-J. Chem. Commun. 2011, 47, 7224-7226. 18

    Coordination Similar to the Ar-Carbamate

    (56%)

  • Seminar Outline

    Part 1

    Suzuki Cross Coupling of Aryl Carbamate and Aryl Sulfamate

    Ox. Addition Selectivity Towards the Guided Site

    Room Temperature Catalyzed Inactivated Electrophile

    Part 2

    Suzuki Cross Coupling of Aryl Ether

    Reductive Demethoyxlation in Aryl Ether

    Possible Application in non-synthetic area

    19

  • Room Temp. Catalyzed Inactivated Suzuki Reaction

    Xing, C.-H.; Lee, J.-R.; Tang, Z.-Y.; Zheng, J. R.; Hu, Q.-S. Adv. Synth. Catal. 2011, 353, 2051-2059. 20

  • The Thinking Trail:

    Catalyst Conversion (%)

    Pd2(dba)3 + 0

    Pd2(dba)3 + 0

    Ni(COD)2 + 0

    Ni(COD)2 0

    Ni(COD)2 + Dppe or Dppf 0

    Ni(PCy3)2Cl2 + 2 PCy3 11

    Ni(COD)2 + 2 PCy3 90 (6hrs), 99 (24hrs)

    Tang, Z.-Y.; Hu, Q.-S. J. Am. Chem. Soc. 2004, 126, 3058-3059. 21

  • Room Temp. Ni Catalyzed Suzuki Coupling

    Xing, C.-H.; Lee, J.-R.; Tang, Z.-Y.; Zheng, J. R.; Hu, Q.-S. Adv. Synth. Catal. 2011, 353, 2051-2059. 22

  • The Importance of Water

    0

    10

    20

    30

    40

    50

    60

    0 1 2 3 4 5

    Yie

    ld (

    %)

    H2O Additive (Equiv)

    Effect of Water in Ni Cat. Suzuki Cross Coupling

    Xing, C.-H.; Lee, J.-R.; Tang, Z.-Y.; Zheng, J. R.; Hu, Q.-S. Adv. Synth. Catal. 2011, 353, 2051-2059. 23

  • The Importance of Water in Suzuki Coupling

    1st equiv of water:

    R-B(OH)2 R-B(OH)3-

    2nd equiv of water: Lower the

    energy of 29 of the

    transmetallation step by 17 kcal

    mol-1

    Quasdorf, K. W.; Antoft-Finch, A.; Liu, P.; Silberstein, A. L.; Komaromi, A.; Blackburn, T.;

    Ramgren, S. D.; Houk, K. N.; Snieckus, V.; Garg, N. K. J. Am. Chem. Soc. 2011, 133, 6352-6363. 24

  • In Excessive Amount of Water

    At Room Temp.

    Ni(PCy3)2Br2 + 2 H2O(xs) Ni(OH)2 + 2PCy3.HBr

    (Pale Green) (Colorless)

    At High Temp.

    Ni(PCy3)2Br2 + 2 H2O(xs) Ni(OH)2 + 2PCy3.HBr

    (Pale Green) (Colorless)

    Solubility:

    Ni(OH)2

  • Conclusion for Part 1

    Compatibility:

    Ni can be a viable replacement for Pd

    Oxidative Addition favors:

    Electronic deficient ring

    Favors at site where Metal coordinate the best. (Lowest Energy)

    H2O is significant to Suzuki coupling at room temperature:

    2 equiv (to the Electrophile)

    1st equiv generates HO- for Borate 2nd equiv lowers the energy of T.S. in Transmetallation

    Too much MAY diminish catalytic effect at low temperature.

    Selectivity:

    Ni: Sulfamate, Carbamate, Ether

    26

  • Seminar Outline

    Part 1

    Suzuki Cross Coupling of Aryl Carbamate and Aryl Sulfamate

    Ox. Addition Selectivity Towards the Guided Site

    Room Temperature Catalyzed Inactivated Electrophile

    Part 2

    Suzuki Cross Coupling of Aryl Ether

    Reductive Demethoyxlation in Aryl Ether

    Possible Application in non-synthetic area

    27

  • Part 2: Suzuki Coupling with Alkyl-Ether

    (Chatani, 2008)

    Tobisu, M.; Shimasaki, T.; Chatani, N. Angew. Chem. Int. Ed. 2008, 47, 4866-4869. 28

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