1. Cobalt-Catalyzed Cross-Coupling Reactions
Abdol R. Hajipour

2. High catalytic activity
Vitamin B12
Cobalt
Readily available
Non-toxic
Low-cost
Stable in air
High catalytic activity

3. These reactions are believed to proceed by an uncommon mechanism involving a carbon-centered radical species. Cobalt complexes can also be used to effect cascade transformations in which radical cyclization is followed by subsequent cross-coupling.
Cobalt-Catalyzed Dimerization of Grignard Reagents

4. Oshima proposed mechanism

5. Hoffman proposed mechanism

6. Scope pf aryl halides in cobalt-catalyzed cross-coupling reaction

7. Proposed mechanism of cobalt-catalyzed radical cyclization/cross-coupling reaction

8. Scope of tandem cyclization/cross-coupling

9. Organozinc compounds
Carbonylation of diorganozinc species using cobalt catalysis

10. e
Synthesis of functionalized arylzinc reagents and their consecutive reaction with acid chlorides
Proposed mechanism for the acylation of aryl zinc species
with acyl chloride using cobalt catalyst

11. One-step synthesis of aromatic ketones from functionalized
aryl bromides and acid anhydrides
Cobalt-catalyzed alkenylation of zinc organometallics

12. Cbalt-catalyzed cross-coupling between aryl zinc species and activated olefins

13. Cobalt-catalyzed allylation of diarylzinc reagents with allyl chloride
Cobalt-catalyzed allylation of diarylzinc reagents with allyl acetate

14. Organocopper
Cobalt-catalyzed cross-coupling between aryl halides and arylcopper compounds

15. General procedure for the cobalt-catalyzed vinylation of functionalized aryl halides with vinyl acetates
Cobalt-catatyzed electrochemical vinylation of aryl halides
using vinyl acetates

16. Proposed mechanism for the vinylation of aryl halides with vinyl acetates

17. Cobalt-catalyzed direct electrochemical cross-coupling
between aryl halides and allylic acetate
Coupling reaction between aromatics chloride and allyl acetate

18. Cross-coupling reaction between heteroaromatic halides and allyl methacrylates
Mechanism of the cobalt-catalyzed electrochemical coupling
between aromatic halides and allylic acetates

19. Aryl chlorides allylation by allyl acetate with Co-Fe-Mn

20. Electroreductive cobalt-catalyzed cross-coupling of aryl halides
Cobalt-catalyzed electrochemical cross-coupling of functionalized
phenyl halides with 4-chloroquinoline derivatives

21. Proposed mechanism for the cobalt-catalyzed formation of biaryls

22. Cobalt-Catalyzed C−H Arylations, Benzylations, and Alkylations with Organic Electrophiles and Beyond
Cobalt-mediated direct functionalized of azobenzene

23. Cobalt-catalyzed C-H arylation with aryl sulfamates

24. Cobalt-catalyzed C-H arylations with carbamates

25. C-H arylation of aromatic imines 10 with aryl chloride 11

26. The mechanism of C-H arylation

27. C-H alkylation of ketamines

28. C-H activation reactions N0 # 1
In our laboratory
C-H activation reactions N0 # 1
Cobalt-Catalyzed C-H Activation/C-O Formation: Synthesis of Benzofuranones

29. Effect of reaction parameters in synthesis of benzofuranones.a)
Entry
Cobalt salt
ligand
RMgBr
Yield [%]b) 1
CoBr2
IMes•HCl
iPrMgBr 52 2
IPr•HCl
48c) 3
SIMes•HCl 57 4
PPh3 64 5
4-OMe-PhMgBr
35c) 6
4-NO2-PhMgBr 7
tBuCH2MgBr 49 8
CoSO4
16c) 9
Co(NO3)2 10
CoCl2 87

30. Plausible catalytic cycle for the cobalt- catalyzed C−H lactonization

31. No # 2
Cobalt-Catalyzed Intramolecular Arylation of 2-Bromo-Aromatic imine via Directed C–H Bond Functionalization: Synthesis of Phenanthridinr Skeleton

32. Scope of Varieties of Acetophenone-derived

33. Plausible Catalytic Cycle for the Cobalt-Catalyzed C−H Functionalizations

34. Nanocatalyst
More surface area
Eliminating the undesired products
Controllable size and morphology
More selectivity and activity
High diversity and capability of chemical modification
Recoverable
Aggregation possibility

35. Cross-coupling reaction No # 1
Application of Co- and CoFe2O4-NPs in C–N and C–O bond
formation: benzimidazole and benzoxazole synthesis
Catalyst preparation:
10 mL
Hydrazine
NaOH 60%
efficient methods for the synthesis of substituted benzimidazoles and benzoxazoles using green and inexpensive cobalt catalysts under ligand-free conditions have been developed. Two different catalysts ofmagnetic and pure cobalt were synthesized and their activities in intramolecular C–O and C–N bond formation reactions were compared. These nanoparticles are easily made, air-stable, low-cost and efficient. Both of the catalysts can be recovered and reused without remarkable loss of activity. A comparison of these two catalytic systems showed that their activities are close to each other; however, the reactions catalyzed by the cobalt nanoparticles were complete in relatively shorter reaction times compared to the cobalt ferrite ones.

36. Catalyst characterization:

39. No # 2
Cobalt nanoparticles supported on ionic liquid functionalized-multiwall carbon nanotubes as an efficient and recyclable catalyst for Heck reaction
we have prepared Co NPs immobilized on imidazolium ionic liquid-functionalized MWCNTs (Co-IL MWCNT) which can be used as an environmentally friendly and economical catalyst for the Heck coupling reaction. This coupling reaction can proceed without the need for an expensive palladium catalyst and toxic ligands in a markedly short reaction time.

40. Catalyst Characterization
FT-IR
TEM

41. No # 3
Multi walled carbon nanotubes supported N-heterocyclic carbene cobalt (ΙΙ) as a novel, efficient and inexpensive catalyst for the Mizoroki–Heck reaction
cobalt supported on direct functionalization MWCNTs as NHC precursor was fabricated for the first time. The prepared catalyst exhibited high catalytic activity for the Mizoroki–Heck reaction. The current strategy is a novel, environmentally friendly and economical way for the Heck reaction using significantly low cobalt loading. It could be recycled and reused six times without obvious cobalt leaching.

42. Catalyst preparation:

43. Catalyst Characterization
FT-IR

44. TEM ICP analysis 0.35 mmol/g (Co / catalyst) CHN analysis N % C % H %
Ligand loading (%)
Theoretical
13.99
79.97
6.04
4/25 mmol/g
Experimental
1.2
12.1
2.1
ICP analysis
0.35 mmol/g (Co / catalyst)

45. No # 4
Pd/Cu-free Heck and Sonogashira cross-coupling reaction by Co nanoparticles immobilized on magnetic chitosan as reusable catalyst
this study highlights the multifaceted advantages of CS as a sustainable material for the textural engineering of macroporous supports, whereas chemical modification of its amino groups with safe and green organic compounds, such as methyl salicylate, allows the tuning of the metal support interaction. Mild and sustainable reaction conditions (palladium and copper-free, polyethylene glycol as solvent, 80 °C) enables Heck cross-coupling catalysis to be performed in good yields with low metal contamination, and easy and good recyclability. This straightforward and sustainable chemistry affords useful and eco-efficient catalysts with many useful properties including their green and easy conditions to produce the catalyst (without using toxic agents and solvent) and good efficiencies for the Heck and Sonogashira coupling reactions. In general, this study presents the first example of the application of the functionalization of magnetic chitosan with methyl salicylate to prepare a stable heterogeneous cobalt complex. The requirements of energy and time for the Heck reaction are extremely minimized in this method compared to the previously report cobalt-catalyzed Heck cross coupling reactions as an inevitable trend in development of green chemistry. Moreover, it is the first report of applying a cobalt catalyst in the Sonogashira reaction.

46. SEM-EDX
TEM

47. Comparison of catalytic activities of our catalystS with rare literature examples for Heck reaction between iodobenzene and methyl acrylate
Entry
Catalyst
Reaction conditions
Time (h)
Yield (%) 1
Nano Co
Co (2 mol%) in NMP at 130 ºC 14 78 2
Co/Al2O3
Co (10 mol%) in NMP at 150 ºC 24 56 3
Co (2 mol%) in NMP at 140 ºC 16 85 4
Co-B
Co (5 mol %) in water/DMF (5/5) at 130 ºC 12 98 5
Co (5 mol %) in toluene at 100 ºC 87 6
Co (3.5 mol %) in PEG at 80 ºC 7
Co (1.1 mol %) in PEG at 80 ºC 88
Note: Further applications of cobalt catalytic system in coupling reactions are under investigation in our laboratory.

48. Thanks for
your time
and attention!