cobalt catalyzed reactions
DESCRIPTION
Cobalt Catalyzed ReactionsTRANSCRIPT
OOVERVIEWVERVIEW
� Introduction
� OXO process
� Cross coupling reactions using Grignard reagents
� Cobalt coupling Michael addition reactions
� Cobalt catalyzed Heck type reactions� Cobalt catalyzed Heck type reactions
� Reductive cyclization and Heck type reactions
� Cobalt catalyzed allylation of 1,3-dicarbonyl compounds
� Coupling of alkenes and alkynes
� Cobalt catalyzed syn-hydrophosphination of alkynes
� Cobalt catalyzed C-N coupling
� Cobalt catalyzed C-S coupling
IINTRODUCTIONNTRODUCTION
� The oxidation state of cobalt in organocobalt compounds
ranges from -1 to +4.
� The most common being -1, 0, +1 and +3.
� Co(0) complexes consists of homoleptic carbonyl: Co2(CO)8and Co4(CO)12.
� Co2(CO)8 is used as a homogeneous catalyst in the
hydroformylation of alkenes.hydroformylation of alkenes.
� It is thermally unstable, decomposing above 50oC to give
Co4(CO)12.
SolidIn Solution
Kamiya, S. Synthesis of organometallic compounds: A practical guide, John Wiley & Sons.
IINTRODUCTIONNTRODUCTION
� Co(I) complexes contain π-acid ligands: Cp, CO, RNC,
and PR3.
� Co(I) complexes are usually five-coordinated and
trigonal bipyramidal.
� In oxidative addition reactions give Co(III) in which one
ligand is eliminated.
� Monocyclopentadienyl (Cp) complexes are one on the
most extensively studied cobalt complexes.
� CoCpL2 (L= PPh3, CO) are capable of catalyzing the
cyclotrimerization of alkynes as well a variety of other
compounds to give other types of bonds.
Kamiya, S. Synthesis of organoetallic compounds: A practical guide, John Wiley & Sons.
IINTRODUCTIONNTRODUCTION
Kamiya, S. Synthesis of organoetallic compounds: A practical guide, John Wiley & Sons.
IINTRODUCTIONNTRODUCTION
� Since the discovery of vitamin B12 coenzyme there has been
much work done on organocobalt (III) complexes with a
metal-carbon bond.
Kamiya, S. Synthesis of organoetallic compounds: A practical guide, John Wiley & Sons.
OXO POXO PROCESSROCESS
• OXO process is the hydroformylation of alkenes (such as
propene) to make aldehydes.
• This process is catalyzed by Rh or Co.
Kamiya, S. Synthesis of organoetallic compounds: A practical guide, John Wiley & Sons.
OXO POXO PROCESSROCESSCatalytic cycle:
• π-Complex formation.
• Hydrometallation to produce an alkyl metal species.
• Coordination of carbon monoxide followed by insertion.
• Reductive cleavage with hydrogen to produce the metal-hydride
intermediate.
Kamiya, S. Synthesis of organoetallic compounds: A practical guide, John Wiley & Sons.
CCROSSROSS CCOUPLINGOUPLING
• Cross-coupling reactions between an organometallic reagent and an
organic halide or triflate.
• Reaction requires a transition metal catalyst. Pd is commonly used.
MechanismMechanism
• Oxidative addition of the halide to the initial palladium(0)complex to form a
palladium(II) species.
• Transmetallation: the nucleophile is transferred from the organometallic
reagent to the palladium and the counter ion moves in the metal.
•The new palladium(II) complex with two organic ligands undergoes reductive
elimination to give the coupled product
Clayden, J.; Greeves, N.; Warren, S.; Wothers, P. Organic chemistry, Oxford University Press, 2001
CCROSSROSS CCOUPLINGOUPLING
• The halide partner must be chosen with care, as β-hydride elimination
would decompose the first intermediate during the slow transmetallation
step.
• The choice for is restricted to substituent's without β-hydrogen atoms:
vinyl, allyl, benzyl, and polyfluoroalkyl halides,triflates, and phosphates have
all been coupled successfully.
•The organometallic reagent can be based on magnesium, zinc, copper, tin,
silicon, zirconium, aluminium, or boron
• The organic fragment can have a wide variety of structures as coupling is • The organic fragment can have a wide variety of structures as coupling is
faster than β-hydride elimination.
Clayden, J.; Greeves, N.; Warren, S.; Wothers, P. Organic chemistry, Oxford University Press, 2001
CCOBALTOBALT CCATALYZEDATALYZED
CCROSSROSS CCOUPLINGOUPLING USINGUSINGCCROSSROSS CCOUPLINGOUPLING USINGUSING
GGRIGNARDRIGNARD RREAGENTSEAGENTS
CCOBALTOBALT CCATALYZEDATALYZED CCROSSROSS
CCOUPLINGOUPLING USINGUSING GGRIGNARDRIGNARD
RREAGENTSEAGENTS• The first cobalt catalyzed cross coupling reaction was described the
homocoupling reaction of Grignard reagents
• In 1939 Gilamn and Lichtenwatler obtained almost quantitative yields
of diphenyl homocoupled product by treating aromatic Grignard reagents
with a stoichiometric amount of cobalt bromide.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Gilman, H.; Lichtenwalter, M. J. Am. Chem. Soc. 1939, 61, 957
CCOBALTOBALT CCATALYZEDATALYZED CCROSSROSS
CCOUPLINGOUPLING USINGUSING GGRIGNARDRIGNARD
RREAGENTSEAGENTS
• Kharasch continued these
homocoupling reactions by isolating
diphenyl compounds in good yields.
• 3 mol % of cobalt chloride required
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Kharasch, M. S.; Fuchs, C. F. J. Am. Chem. Soc. 1941, 63, 2316
CCOBALTOBALT CCATALYZEDATALYZED CCROSSROSS
CCOUPLINGOUPLING USINGUSING GGRIGNARDRIGNARD
RREAGENTSEAGENTS• In 1943 Kharasch reported the first alkenylation reaction between
Grignard reagents and vinyl halides catalyzed by cobalt chloride.
• Catalytic amount of cobalt chloride (2.5 mol %).
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Kharasch, M. S.; Fuchs, C. F. J. Am. Chem. Soc. 1943, 65, 504
CCOBALTOBALT CCATALYZEDATALYZED CCROSSROSS
CCOUPLINGOUPLING USINGUSING GGRIGNARDRIGNARD
RREAGENTSEAGENTS
• This work to still ongoing.
Yoshikai recently reported a
quaternary catalytic system
consisting of CoBr2, P(3-ClC6H4)3,
tBuCH2MgBr, and pyridine
promotes hydroarylation of an promotes hydroarylation of an
internal alkyne with an aromatic
imine through chelation-assisted
CH bond cleavage
Lee, P. S.; Fujita, T.; Yoshikai, N. J. Am. Chem. Soc. 2011, 133, 17283
CCOBALTOBALT CCATALYZEDATALYZED CCROSSROSS
CCOUPLINGOUPLING USINGUSING GGRIGNARDRIGNARD
RREAGENTSEAGENTS• Alkenylation
• From aromatic organomagnesium reagents
• From vinylic Grignard reagents
• From aryl halides and alkenyl acetates
• Aryl-Aryl Cross coupling
• From aromatic organometalic reagents
• From two aromatic halides• From two aromatic halides
• Alkynylation
• Benzylation of acetylenic Grignard reagents
• Alkylationof acetylenic Grignard reagents
• Alkenylation of acetylenic Grignard reagents
• Csp3-Csp2 Cross-coupling
• Allylation
• Benzylation
• Alkylation
• Acylation
• From organometallic compounds
• Cobalt- mediated acylation of aryl bromides
CCOBALTOBALT--MMEDIATEDEDIATED MMICHAELICHAEL
AADDITIONDDITION
• Giese describes a diastereoselective conjugative addition using
Vitamin B12 as a catalyst and Zn as a reducing agent
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
CCOBALTOBALT--MMEDIATEDEDIATED MMICHAELICHAEL
AADDITIONDDITION• Pfaltz developed the synthesis of C2-
symmetric bis-amides.
• He found by this ligand in Michael
addition reactions high ee could be
obtained but with low yield.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
End, N.; Macko, L; Zehnder, M.; Pfaltz, A. Chem. Eur. J. 1998, 4, 818
Chen, C.; Zhu, S. F.; Wu. X. Y.; Zhou, Q. L. Tetrahedron: Asymmetry 2006,
17, 2761
• Using similar ligands Cheng
reported the Michael addition of
malonates to chalcone derivatives
using cobalt complexes and Et2Zn
• Good yield and moderate ee.
CCOBALTOBALT--MMEDIATEDEDIATED MMICHAELICHAEL
AADDITIONDDITION
•Bergman reported a one-pot,
direct C-H functionalizaion of
alkenes meditated by
[CpCo(NO)2].
•A variety of Michael acceptors •A variety of Michael acceptors
can be used
Zhao, C.; Toste, F. D.; Bergman, R. G. J. Am. Chem. Soc. 2011,
133, 10787
CCOBALTOBALT--CCATALYZEDATALYZED HHECKECK TTYPEYPE
RREACTIONSEACTIONS
• The “Heck Reaction” is a powerful tool in carbon-carbon bond formation
• There are limitations regarding substrate choice, which are limited to
aryl, heteroaryl, vinylic and benzylic halides and triflates as the
presence of an sp3 carbon in the β-position carrying a hydrogen rapidly
results in β-hydride elimination.
• Cobalt catalyzed Heck type reactions avoids this drawback.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Clayden, Greeves, Warren, Wothers, Organic chemistry, 1313
CCOBALTOBALT--CCATALYZEDATALYZED HHECKECK TTYPEYPE
RREACTIONSEACTIONS• In 1991 Branchaud reported the first cobalt catalyzed Heck type reaction
between styrene and various alkyl halides.
• Reaction was catalyzed using Cobaloxine (II) and requires daylight.
• The use of 3o bromides fail.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
CCOBALTOBALT--CCATALYZEDATALYZED HHECKECK TTYPEYPE
RREACTIONSEACTIONS
[A] CoCl2.dpph reacts with
Me3SiCH2MgCl.
[B] Monoelectronic transfer to the
alkyl halide forming a CoI species.
[C] CoI reacts with Me3SiCH2MgCl
forming an intermediate.
[D] Then reacts with the benzylic
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
[D] Then reacts with the benzylic
radical forming the organocobalt [E].
[F] The Heck product is obtained from
[E] by β-hydrogen elimination.
CCOBALTOBALT--CCATALYZEDATALYZED HHECKECK TTYPEYPE
RREACTIONSEACTIONS
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Ikeda, Y.; Yorimitsu, H.; Shinokubo, H,; Oshima, K. Adv, Synth. Catal. 2004, 346, 1631
RREDUCTIVEEDUCTIVE CCYCLIZATIONYCLIZATION AANDND
HHECKECK--TTYPEYPE RREACTIONSEACTIONS
�INTERMOLECULAR RADICAL CYCLIZATION
�INTRAMOLECULAR RADICAL CYCLIZATION
RREDUCTIVEEDUCTIVE CCYCLIZATIONYCLIZATION AANDND
HHECKECK--TTYPEYPE RREACTIONSEACTIONS
�INTRAMOLECULAR RADICAL
CYCLIZATION
• Radical mediated aryl-aryl
coupling
• The first reported case was by
Tiecco in 1965
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Tiecco, M. Chem. Commun. 1965, 555
Tiecco in 1965
• Methylmagnesium iodide was
used in a suspension of cobalt
chloride in an ethereal solution
affording phenanthrenein 75%
yield
RREDUCTIVEEDUCTIVE CCYCLIZATIONYCLIZATION AANDND
HHECKECK--TTYPEYPE RREACTIONSEACTIONS
• In 1982 Tada reported the
reductive cyclization of 2-
propargyloxyalkyl bromides in
the presence of cobaloxime.
• Hoffmann applied this method
to the synthesis of various to the synthesis of various
heterocyclic compounds.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Okabe, M.; Abe, M.; Taba, M. J. Org. Chem. 1982, 47, 1775
Abe, M.; Taba M. J. Org. Chem. 1982, 47, 5382
Last, K.; Hoffmann, H. M. R. Synthesis1989, 901
RREDUCTIVEEDUCTIVE CCYCLIZATIONYCLIZATION AANDND
HHECKECK--TTYPEYPE RREACTIONSEACTIONS
• Pattenden reported the radical
cyclization of 2-allyloxyalkyl
bromides using Vitamin B12 or
cobaloxime (I)
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
RREDUCTIVEEDUCTIVE CCYCLIZATIONYCLIZATION AANDND
HHECKECK--TTYPEYPE RREACTIONSEACTIONS
�INTERMOLECULAR RADICAL CYCLIZATION
• Typically this reaction is
catalyzed using Pd or Ni due
to the facile oxidative
addition of aryl halides to Pd
andand
Ni(0) metal complexes..
• Yamamoto shows the
addition of vinylpalladium
species to carbon
electrophiles such as a
carbonyl group
• This was the first
palladium-catalyzed
nucleophilic cyclic
vinylpalladation of aryl
ketones with alkynes to
produce
Indenols in good to high
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Quan, L. G.; Gevorgyan, V.; Yamamoto, Y. J. Am. Chem. Soc. 1999, 121, 3545
RREDUCTIVEEDUCTIVE CCYCLIZATIONYCLIZATION AANDND
HHECKECK--TTYPEYPE RREACTIONSEACTIONS
• Cheng first reported that cobalt
phosphine complexes successfully
catalyse the reaction under mild
conditions to afford indenol derivatives
with excellent regioselectivity and in high
yields
• The cobalt catalyzed system is more
efficient than the palladium and nickel
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Chang, K. J.; Rayabarapu, D. K.; Cheng, C. H. Org. Lett. 2003, 5, 3963
Chang, K. J.; Rayabarapu, D. K.; Cheng, C. H. J. Org. Chem. 2004, 69, 4781
efficient than the palladium and nickel
catalysts for this
carbocyclization reaction.
RREDUCTIVEEDUCTIVE CCYCLIZATIONYCLIZATION AANDND
HHECKECK--TTYPEYPE RREACTIONSEACTIONS
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Chang, K. J.; Rayabarapu, D. K.; Cheng, C. H. Org. Lett. 2003, 5, 3963
Chang, K. J.; Rayabarapu, D. K.; Cheng, C. H. J. Org. Chem. 2004, 69, 4781
CCOBALTOBALT CCATALYZEDATALYZED
AALLYLATIONLLYLATION OFOF
1,31,3--DD1,31,3--DDICARBONYLICARBONYL
CCOMPOUNDSOMPOUNDS
CCOBALTOBALT CCATALYZEDATALYZED AALLYLATIONLLYLATION OFOF
1,31,3--DDICARBONYLICARBONYL CCOMPOUNDSOMPOUNDS
• Iqbal reported the allylation of 1,3-dicarbonyl compounds using a cobalt
catalyst.
• Reactions were conducted under neutral conditions, compared to Pd
catalyzed reactions
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
CCOBALTOBALT CCATALYZEDATALYZED AALLYLATIONLLYLATION OFOF
1,31,3--DDICARBONYLICARBONYL CCOMPOUNDSOMPOUNDS
• Reactions can also be repeated with allylic alcohol.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
CCOUPLINGOUPLING OOFF AALKENESLKENES AANDND
AALKYNESLKYNES• Commonly copper mediated reactions are used for the preparation of
conjugated diynes.
• In 2001 Kraff reported cobalt catalyzed dimerization of terminal alkynes.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Krafft, M. E.; Hirosawa, C.; Dalal, N,; Ramsey, C.; Stiegman, A. Tetrahedron Lett. 2001, 42, 7733
CCOUPLINGOUPLING OOFF AALKENESLKENES AANDND
AALKYNESLKYNES•Cheng followed suit with the reductive dimerization of conjugated alkenes,
which were highly regio- and stereoselective.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Wang, C. C.; Lin, P. S.; Cheng, C. H. Tetrahedron Lett. 2004, 45, 6203
Chang, H. T.; Jayanth, T. T.; Wang, C. C.; Cheng, C. H. J. Am. Chem. Soc. 2007, 129, 12032
dppe=1,2-Bis(diphenylphosphino)ethane
CCOBALTOBALT--CCATALYZEDATALYZED
SSYNYN--
HHHHYDROPHOSPHINATIONYDROPHOSPHINATION
OFOF AALKYNESLKYNES
CCOBALTOBALT--CCATALYZEDATALYZED SSYNYN--
HHYDROPHOSPHINATIONYDROPHOSPHINATION OFOF
AALKYNESLKYNES• Reaction traditionally with lanthanides, Pd or Ni
• Stereoselectivity of these reactions depend on the nature of the substrate
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Mimeau, D.; Gaumont, A. C. J. Org. Chem. 2003, 68, 7016
CCOBALTOBALT--CCATALYZEDATALYZED SSYNYN--
HHYDROPHOSPHINATIONYDROPHOSPHINATION OFOF
AALKYNESLKYNES• Oshima developed a cobalt catalyzed universal stereoselective
hydrophosphination reaction of alkynes with diphenylphosphine and
butyllithium giving mainly syn-addition product.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Ohmiya, H.; Yorimitsu, H.; Oshima, K. Angew. Chem. Int. Ed. 2005, 44, 2368
CCOBALTOBALT--CCATALYZEDATALYZED SSYNYN--
HHYDROPHOSPHINATIONYDROPHOSPHINATION OFOF
AALKYNESLKYNES• Product can be used to perform Wittig reaction.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Ohmiya, H.; Yorimitsu, H.; Oshima, K. Angew. Chem. Int. Ed. 2005, 44, 2368
CCOBALTOBALT CCATALYZEDATALYZED CC--N N
CCOUPLINGOUPLING• Cobalt-porphyrin catalyzed C-H amination has been extensively
examined by Cenini.
• Reactions are limited to cyclohexane.
• Substrates have been extended to benzylic C-H bonds.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Cenini, S.; Tollari, S.; Penoni, A.; Cereda, C. J. Mol. Catal. A. 1999, 135
Cenini, S.; Gallo, E.; Penoni, A.; Ragaini, F.; Tollari, S. Chem. Commun. 2000, 2265
CCOBALTOBALT CCATALYZEDATALYZED CC--N N
CCOUPLINGOUPLING
• Yamaguchi developed new • Yamaguchi developed new
methodology to prepare N-aromatic-
containing tertiary amines that are
useful
building blocks for bioactive
molecules.
• He was the first to use N-aromatic
2-chloro compounds for C–N bond-
forming reactions.
Toma, G.; Yamaguchi, R. Eur. J. Org. Chem. 2010, 6404
Toma, G.; Fujita, K.; Yamaguchi, R. Eur. J. Org. Chem. 2009, 4586
CCOBALTOBALT--CCATALYZEDATALYZED CC--S S
CCOUPLINGOUPLING• Typically C-S coupling is conducted using Cu, Pd or Ni catalyst under
harsh conditions.
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Bates, C. G.; Gujadhur, R. K.; Venkatamaran, D. Org. Lett. 2002, 4,
3517
CCOBALTOBALT--CCATALYZEDATALYZED CC--S S
CCOUPLINGOUPLING• Cobalt-catalyzed C-S coupling requires milder conditions.
• Low catalytic loading
Cahiez, G.; Moyeux, A. Chemical Reviews 2010, 110, 1435-1462
Wong, Y. C.; Jayanth, T. T.; Cheng, C. H. Org. Lett. 2006, 8, 5613
CCONCLUSIONONCLUSION
• Cobalt and its complexes can catalyze many many different
reactions including:
• Cross-coupling reactions
• Heck-type reactions
• C-N coupling
• C-S coupling
• and many more