recent progress in sp 3 c-h activation catalyzed by palladium bo yao
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Recent Progress in sp3 C-H Activation Catalyzed by
Palladium
Bo Yao
Concepts related with C-H activationC-H activation
In general definition, C-H activation should refer to any chemical process that increases the reactivity of C-H bond.In organometallic definition, C-H activation refers to the formation of a complex wherein the C-H bond interacts directly with the metal catalyst or reagent. The complexes often afford a C-M intermediate in the absence of free radical or ionic intermediates.
“C–H bond activation” is frequently used as an organometallic term to describe certain metal-mediated processes.
C-H transformation: C-H bonds are transformed into C-C, C-X bondC-H oxidation: The oxidation valence of carbon is increased.C-H functionalization: New functional groups are connected to the carbon.Oxidative functionalization: Oxidant is needed for the functionalization.C-H arylation/halogenation/oxygenation/metallation
H FGM
H
M
A few decades later in 1968, Halpern formulated the need for new approaches to the activation of C–H bonds with a particular focus on saturated hydrocarbons. C–H bond activation, equated with “dissociation of carbon–hydrogen bonds by metal complexes”, was identified as one of the most important challenges in catalysis
Clearly, a new reactivity mode, other than radical or ionic substitution, had been discovered and the term “activation of saturated hydrocarbons” was used.
Challenge in sp3 C-H activation
H
R direct C-C, C-O, C-N and C-X formation
Fujiwara, Sanford, Yu, Shi, Fagnou, Daugulis, Gaunt, etc....
Pd Friedel-Crafts routeElectrophilic attackConcert deprotonation
with Pd(II), Pd(III), or Pd(IV)as reactive intermediate
R3H
direct C-C, C-O, C-N and C-X formation
R2R1
Pd
1. High bond dissociation energy2. Lack of -group to interact with transition metals3. Difficulty in controlling selectivity
Strategies for sp3 C-H activation
1. Oxidation of sp3 C-H bond ajacent nitrogen and oxygen
NPh
HN
+
NPh
NH
5 mol% CuBrTBHP, 50 °C
79%
Cross-Dehydrogenative-Coupling(CDC) catalyzed by Cu and Fe
Chao-Jun Li , J. Am. Chem. Soc. 2005, 127, 6968-6969
NCH3
CH3
NCH2CN
CH35 mol% RuCl3nH2O
NaCN, O2 (1 atm)MeOH/AcOH(3:1)
60 °C
Shun-Ichi Murahuashi, J. Am. Chem. Soc. 2003, 125, 15312-15313
Strategies for sp3 C-H activation
2. sp3 C-H activation triggered by oxidative addition intramolecularly
R3H
R2
X
R3
H
R2
Pd LX
R3
R2
Pd LY
-HXR3
Y
R2
H
R3
R2
I
OCH3
H3CO
H3CO
O
4 mol% Pd(OAc)2K2CO3, nBu4NBr
DMF, N23d, 100 °C
90%
PdI
OCH3
Pd
OH3CO
OH3CO
O
Pd
PdI
H3CO
O
H3CO
PdI
H3CO
O
H3CO Pd
-HI
-+HI
-HI
Pd(0)
Gerald Dyker, Angew. Chem. Int. Ed. Engl. 1992, 31, 1023-1025
Strategies for sp3 C-H activation
3. sp3 C-H activation by directing groups promoted C-H cleavage
R3H
R2
DGR3
Pd
R2
DGR3
Y
R2
DGY
OMe
N
O
OMe
Me
OMe
N
O
OMe
Me
Pd
Cl
PdCl2,NaOAcAcOH75%
B(OH)2
a) Ag2O, DMF 86%
OMe
N
O
OMe
Me
b) MeSO3H, CH2Cl2 83%
a) PdCl2,NaOAcAcOH
b) Then CO (40 atm), MeOHc) SiO2, CHCl3
NH
O
OMe
N
O
OH
Teleocidin B-4 Core
OMe
N
O
OMe
Me
Pd
Cl
65% (6:1)
Dalibor Sames, J. Am. Chem. Soc. 2002, 124, 11856-11857
Recent progress for sp3 C-H activation catalyzed by palladium
Triggered by oxidative addition
I 2.5 mol% Pd(OAc)2K2CO3, nBu4NBr
DMF, N24d, 105-110 °C
75%
Pd(II)-Pd(IV)
Gerald Dyker, J. Org. Chem. 1993, 58, 6426-6428Angew. Chem. Int. Ed. Engl. 1994, 33, 103-105
Cascade reaction
Br R1 R2
R2R1
R1
R2 = H
R2 = Me
Pd(OAc)2P(o-tol)3 or F-TOTPK2CO3
DMF100-150 °C
R1 = CN, COOR, CH2OTIPS
Pd(OAc)2(tBu3PH)BF4K2CO3
DMF140 °C
Olivier Baudoin, J. Am. Chem. Soc. 2008, 130, 15157-15166; Angew. Chem. Int. Ed. 2009, 48, 179-182Angew. Chem. Int. Ed. 2003, 42, 5736-5740; Chem. Eur. J. 2007, 13, 792-799Adv. Synth. Catal. 2007, 349, 2054-2060
Keith Fagnou, J. Am. Chem. Soc. 2007, 129, 14570-14571Nobutaka Fujii and Hiroaki Ohno, Org. Lett. 2008, 10, 1759-1762
Br
X
Pd(OAc)2 (2.5 mol%)PCy3-HBF4 (6 mol%)
Cs2CO3, tBuCOOHsolvent, heat
R2
CH3
R1X
R2R1
X= O, N-PG
Recent progress for sp3 C-H activation catalyzed by palladium
Triggered by oxidative addition
(HO)2B
+
Br
tBu
tBuPd2(dba)3 (1 mol%)Ligand (4 mol%)K3PO4, toluene
tBu
99% tBu
tBu100 °C, 18h
I
O EWG Pd
O
LL
EWGH
R1
R2
O EWG
H
R1
R2 Helena C. Malinakova,Org. Lett. 2002, 4, 3679-3681Organometallics 2003, 22, 2961-2971
Stephen L. Buchwald, J. Am. Chem. Soc. 2005, 127, 4685-4696
More work in this field
I
CH3
CH3
Pd(OAc)2, KOAcDMF, N2, 105°C, 18h
norbornene
H3C
CH2
H3C
H2C
+
Marta Catellani,Chem. Commun. 2000, 2003-2004
X
X'+
BrMg
Pd2(dba)3 (1.5 mol%)tBu3P (6 mol%)THF, rt, 20h
99%
Qiao-Sheng Hu,Angew. Chem. Int. Ed. 2006, 45, 2289-2292Tetrahedron 2008, 64, 2537-2552
N
X N
Pd(OAc)2, P(p-tol)3
Cs2CO3, 110 °C20hEWG
EWG
X = Br, I
Paul Knochel,Angew. Chem. Int. Ed. 2006, 45, 3462-3465Chem. Asian J. 2007, 2, 416-433
Recent progress for sp3 C-H activation catalyzed by palladium
Directing group promoted C-H cleavage
O-methyl oxime
R
NMe
R2 R1
MeO
Me
N
MeMe
MeOPd
AcO
2R
N
R2 R1
MeO
OAc
Pd(OAc)2, PhI(OAc)2AcOH, Ac2O or CH2Cl280-100 °C
tBu
NMeO
OAc
5 min, 86%
N OAcH
H
MeO
81%
N O
OAc
44%
Walter S. McDonald and Bernard L. Shaw, J. Chem. Soc., Dalton Trans. 1980, 1992Melanie S. Sanford, J. Am. Chem. Soc. 2004, 126, 14570-14571
β-C-H activation
Recent progress for sp3 C-H activation catalyzed by palladium
Directing group promoted C-H cleavage
8-aminoquinoline amide
Olafs Daugulis, J. Am. Chem. Soc. 2005, 127, 13154-13155J. Am. Chem. Soc. 2010, 132, 3965-3972Org. Lett. 2005, 7, 3657-3659E. J. Corey, Org. Lett. 2006,8, 3391-3394
β-C-H activation
AuxiliaryNH
O
5 mol% Pd(OAc)2ArI, base, solvent Auxiliary
NH
OAr
SMe
NH
O
N
Me
MeO
O
toluene, CsOAc110 °C 79%
SMe
NH
O
OBn tBu
t-Amyl-OH, K2CO390 °C 65%
SMe
NH
O
Br
t-Amyl-OH/H2O, K2CO390 °C 60%
N
NH
O Me
Me
t-Amyl-OH,Cs3PO490 °C 79%
N
NH
ON
O
O
Me
t-Amyl-OH,Cs3PO490 °C 76%
N
NH
O Me
MeO
neat, AgOAc110 °C 92%
N
Me
AcOH, AgOAc110 °C 51%
10 mol% Pd(OAc)2For R-B(OH)2:Ag2O, BQ, 100 °Ctert-amyl alcohol
N
R2
R1
R
For Methylboroxine:Cu(OAc)2, HOAc, O2100 °C
Jin-Quan Yu, J. Am. Chem. Soc. 2006, 128, 12634-12635
Recent progress for sp3 C-H activation catalyzed by palladium
Directing group promoted C-H cleavageCarboxylate amide and acid
β-C-H activation
Jin-Quan Yu, J. Am. Chem. Soc. 2007, 129, 3510-3511J. Am. Chem. Soc. 2008, 130, 7190-7191J. Am. Chem. Soc. 2009, 131, 9886-9887J. Am. Chem. Soc. 2010, 132, 3680-3681J. Am. Chem. Soc. 2010, 132, 17378-17381
10 mol% Pd(OAc)2BQ, Ag2O, K2CO3tBuOH/DMF, 70 °C, 18h
NNH-OMe
O
PhB(OH)2
10 mol% Pd(OAc)2BQ, Ag2O, K2CO3
2,2,5,5-tetramethylTHF70 °C, 18hiBu-B(OH)2
10 mol% Pd(OAc)2BQ, K2CO3, air and N280 °C, 48 h
10 mol% Pd(OAc)2BQ, Ag2CO3, K2HPO4tBuOH, 100 °C, 3h
Me
Me
COOH
Ph
BO
OPh
10 mol% Pd(OAc)2 Ag2CO3, K2HPO4
tBuOH, NaOAc130 °C, 3h
PhI
COOH
Me
Ph
38%
20%
Me COOH
PhPh
70%, 5:2
Me
Me
COOH
Ph
O
O
Ph
NH-OMe
O
iBu
60%
iBu-B(OH)2
58%75%
10 mol% Pd(OAc)220 mol% Cy-JohnPhosCsF, ArI, 3A MS, toluene
R2
R1 Me
NHX
OX = C6F5
R2
R1
NHAr
O
Ar
N
OR1
R2 Ar
BnO2C CO2Bn
X = C6F5, p-CF3-C6H4
10 mol% Pd(OAc)2LiCl, Cu(OAc)2, AgOAcDMF, N2, 120 °C
X = p-CF3-C6H4
10 mol% Pd(OAc)2AgOAc, KH2PO4, TEMPOn-Hexane130 °C
N
OR1
R2 Ar
O
Recent progress for sp3 C-H activation catalyzed by palladium
Directing group promoted C-H cleavage
Jin-Quan Yu, Angew. Chem. Int. Ed. 2005, 44, 2112-2115Angew. Chem. Int. Ed. 2005, 44, 7420-7424Org. Lett. 2006, 8, 5685-5688
Diaselective oxidation trinuclear alkyl-Pd complex
OxaR1
R2
OAc10 mol%Pd(OAc)2Dodecanoyl peroxideAc2O, O2, 50 °C
Oxa =O
NtBu
OxaR1
R2
Me
OxaR1
R2
I
10 mol%Pd(OAc)2I2, PhI(OAc)2CH2Cl2, 24 °C
OxaR1
Me
OAc
OxaR1
Me
I
diaselectively
OxaR1I
I
R1
Oxa
10 mol%Pd(OAc)2IOAcEtOAc, 100 °C
(PhCOO)2
Benzene115 °C
β-C-H activation
N
ON
O
Ar
2.5 mol% Pd2(dba)35 mol% X-Phos1 eq. ArI3 eq. NaOt-Bu in toluene110 °C(mw), 45 min
(1.5 eq.)
N
NBz
5 mol% Pd(OAc)212 mol% Dave-Phos1 eq. ArI3 eq. Cs2CO3 in DMF70 °C, 16h
(1.1 eq.)
N
NBz
Ar
André B. Charrette,Org. Lett. 2008, 10, 1641-1643
Keith Fagnou, J. Am. Chem. Soc. 2008, 130, 3266-3267
RN
Boc
H
cat. Pd(OAc)2IOAc, DCE, 60 °C
RN
Boc
OAc
Melanie S. Sanford, J. Am. Chem. Soc. 2005, 127, 7330-7331
N
R
5 mol% Pd(OAc)2[Ph2I]BF4, 100 °C
N
RPh
R = H, 72%R = Ph, 60%
NO
NH
5 mol% Pd(OAc)2AgOAc, ArI, no solvent70 - 130 °C
R
NO
NH
RAr
α-C-H activation
Olafs Daugulis, J. Am. Chem. Soc. 2005, 127, 13154-13155
Jin-Quan Yu, Org. Lett. 2006, 8, 3387-3390
γ-C-H activation
Recent progress for sp3 C-H activation catalyzed by palladium
Other metalsFe, Ni, Cu, Ru, Rh, Pt,
Ir…
1. Find directing groups which are easy to attach to and deattach from substrates.
2. Develop the methods with milder condition and broader scope.
3. Site-selective C-H activation.
4. Mechanism is far from clear.
Challenges
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