Organometallic Study Meeting

2011/10/6 K.Oisaki

Chapter 17. Catalytic Carbonylation
17.1 Overview
O
H3CHor
OHORO
H3CO

HHor
H

CH3

N
R2

RR

CH3OH

Ar-X or alkene
R'OH

Rh or Ir cat.

Pd cat.

OC

alkene, H2

R1

R

R

OH

O
X

Co cat.

R

Co, Mo, Rh
Ru, Ir, Ti cat.

Pd cat.
alkenenOorOR'epoxide/aziridine

carbon monooxide

Co or Rh cat.

OOOO

alkenealkyne17.2. Carbonylation to Produce Acetic Acid
17.2.1. Rh-catalyzed carbonylation of MeOH to produce AcOH (Monsanto Process)
RhI(CO)2I2
CH3OH + COO
commercialized in 1970

30-40 atm, 180 oC

H3COH<Mechanism>

kinetically unstablein the absense of CO

rate-determining step
CH3OH

detected by IR( = 2055, 1985 cm-1)
CH3I
I
non-metalliccycle

HI

CO–
CH3
I
CORh
I
COI
oxidative
insertion
addition (SN2)
–Rh

H2O

I

Organometallic
Cycle

COdimer(X-ray)

–I
Rh
I

COCH3COI
reductive
elimination

O
H3C

I
IRh

O
H3C

I
OH

–

CO
COCH3COI

microreversibility was confirmed by oxidative addition of AcI to Rh(CO)2I2I–
COCH3 ––CH3O
O
I
COCO
I+COI
Rh
Rh
Rh
H3C
II
COI
COI
COI

CO
0th order

17.2.2. Rh-catalyzed carbonylation of MeOAc to produce Ac2O (Eastman Process)
RhI(CO)2I2 , LiI

O
H3C

O

CH3

<Mechanism>+ COOanhydrous conditions

H3C

O

commercialized in 1983
CH3O

O
H3C

CH3O

*HI works similarly instead of LiI.

CH3I

COI

LiI

LiI-cyclie

LiOAc

CO–Rh
ICOO
H3C
O
H3C

I

Same cat cycle
as Monsanto ProcessOO

CH317.2.3. Ir-catalyzed carbonylation of MeOH to produce AcOH (Cativa Process)established in 1990s
O

Ir(CO)2I2
CH3OH + CO

<Mechanism>
CH3COIr
COI

I
I

CH3I

COIr

ICO–

role of promoter = iodide acceptorIoxidative
addition

insertion

fast(Ir > 150 x Rh)

rate-determining step
(Rh > 105 x Ir)

I–
COI

slow

I

COCH3COIr
COI

1/2 [Ru(CO)3I2]2 + CO

I–

COI
Ir

COCH3COI
I

AcOH

CH3COIr
COI

Ru(CO)3I3

O
I

than Rh–

reductiveelimination

H3COH

the rate depends on [CO], [H2O], [MeOAc], [MeI], [Ru promoter], [Ir](nonlinear)(Rh system only depends on [Rh] and [MeI])

detected by IR( = 2100, 2047 cm-1)
MeOH

I

H3C

[Ru(CO)3I2]2(promoter)# 5 times more active# more H2O tolerant# more soluble catalyst# less expensive metal

I
COCH3
COIr
COCO
neutral

CO

OC

f ast
x ~20I

COCH3COIr
COI–17.3. Hydroformylation
17.3.1. Overview
17.3.2. HCo(CO)4 catalysis (Oxo process)
HHCo(CO)4+ CO/H2(1/1)

R<Mechanism>Co2(CO)8H
R
branched (b)

HH2OC

Co

OCCOO
H

Co

H

Co

COOC

COH

OC

Hd 8, 18e

H

R

Co

d 8, 18e

OCCOR

reversible &isomerizableO d 8, 16e

Co

HCOOC
COOC

R
H

CO

Co
CO H

R

d 8, 16e

Co
COR

OCCOR

OC

COCOO

Co

H2

rate-determining step
(rate dependency = [H2][CO]-1)

COlinear (l)COO

d 6, 18e
product R

H

COd , 16e

COH

R8COH

OH

CO

CO

H+120-170 oC
200-300 atm

CO
d 8, 18e

OCO

R

d 8, 18e# high pressure of CO is required to suppress cat decomp (formation of Co cluster or metallic Co)# all reactions have the potential to be reversible# l/b ratio = 3~4 : 1 at best

17.3.3. HCo(CO)3(PR3) catalysis

stable, high MW phosphine(industrially fabored)(PR3 = PnBu3)

C=C isomerization is very fast.

17.3.4. Rh catalysis
Rh(CO)2(acac)
PPh3+ CO/H2
(1/1)

RH

70-120 oC
10-50 atm

OH
H

R+RH

<reactivity>
R'R

commercialized in 1970s
lower pressure
improved l/bless byproductlab-scale application

OR''RR'R

R

R'<Mechanism>rate-determining step
(rate ∝ [H2]0[alkene][Rh][PR3]-1[CO]-1)

geometrical isomer
is observed by NMR
H
CO/H2Rh(CO)2(acac)

Ph3P

PPh3Rh

H
COCO

Ph3P

CO
PPh3RhCOR

PPh3COH

O
H

Rh

H

Ph3P
H

PPh3

H
product R

H

PPh3O

R

Rh

OC
PPh3

R
H2
CO
Ph3P

Rh
PPh3

COO
H

Ph3P

R

PPh3H

CO
Ph3P

CORh

OC
PPh3H

Rh

R

R

<Phosphine Effect>
empirical: wider B.A. gives better l/b ratio
HPPP= MM caluculated

COP

H
COCO

CO/H2 (6 atm), 34oC

empirical:
eq:more EWG

COBA = 113oeq-eq coordinationis confirmed by
X-ray and NMR.

irreversible alkene
insertion originatedhigh selectivity.

H

O

RhH(CO)2(BISBI) (4mM)

C4H9RhCOeq-eq cat.
bite angle > 90o

ap-eq cat.
bite angle < 90oRh
P
Ph2P

P

M natural bite angle

Ph2
PRh

HCOO+HC4H9C4H9l/b = 66.5
(cf. l/b = 2.1/ for dppe (BA = 85o))

HLRh

faster reaction
high l/b selectivity

COOC
L'ap:more EDG

Piet W. N. M. van Leeuwen et al. JACS 1998, 120, 11616.

[eq-eq]-[ap-eq]

PAr2
S=O

[eq-eq]+[ap-eq]
of RhH(CO)2(L)PAr2
thi-xantphos

Rbite angle does
not always correlate.

(Ar)similar B.A.

most important effect of using
electron-poor ligand is tofacilitate CO dessociation
HLRh

CO+alkene
COOC
conditions:
CO/H2 = 1, P(CO/H2) = 20 bar, ligand/Rh = 5
substrate/Rh = 637, [Rh] = 1.00 mM

L'destablize

fasterHLRh

OCL'R

<Phosphile Ligand># high l/b ratio# faster reaction# suppressed side reaction(hydrogenation)<Scope>internal alkene

acetalw/ directing
group
olefin with EWG gives branched product.

<Enantioselective reaction>
challenges
branched product should be selectively formed.
simple alkene's directing nature is small.
racemization must be suppressed.
chiral phosphine is far from reaction space.
successful ligand families
Babin & W hiteker

Nozaki & Takaya

van Leeuwen & ClaverLandisscope with Rh-BINAPHOS

than PAr3

17.4. Hydroaminomethylation
HCO/H2R

Rh cat.

RR2NH
H2HOcat.

H H
RHNR2

<Scope>usually linear major.

sameabove

biphasic systemtargeting fine chemicals<Mechanism>

challenges# prevent catalyst deactivation with excess amines# e-rich cat enough to reduce e-rich enamine not to prevent hydroformylation

17.5. Hydrocarboxylation / Hydroesterification
examplePd/L cat.
acid co-cat.
+ R'OH

ROOR'R

COOOorR

R = alkyl

OH

OR'MeO

R = arylnaproxen<Scope>12,000 TON/hr(ligand = DTBPMB)

intramolecular rxn

50,000 TON/hr @ 60oC
high FG tolerancealkyne
L = 2-(6-Me-Py)PPh2<Mechanism>

depends on the ligand nature.

OL
OMePd

O

OMe

COL
OMe

L

PdHL

hydride cycle

alkoxide cycle
MeOH

MeOH

OL

OPd

L

OOMe
LL

Pd

L
OMe

LPd

L

LCOcopolymer

copolymer

CO(more probable in Pd/DTBPMB)

Pd

17.6. Carbonylation of Epoxides / Aziridines
X + COR(X = O or NR')

<Scope>Alper's system

O

Co(CO)4 cat.
acid co-cat.

X
R

Coates' system (5 = [CrIII(Et8-porphyrinato)(thf)2][Co(CO)4])(PPN = bis(triphenylphosphine)iminium)

double carbonylation

ring-opening carbonylationaziridines

addition of Lewis acid acclerate the rxn.
Co2(CO)8 + Ru3(CO)12 system
Co2(CO)8 + 1,10-Phen + BnBr system
w/o H2<Mechanism>17.7. Carbonylation of Organic Halides (Carbonylative Cross Coupling)
OPd cat.
R X + CO + Nu

RNu

scope is similar to that of cross coupling.
R = alkyl is remains to be developed.

(Nu = R'OH, R'2NH, R'-M)<Scope>review: Nicolaou, K. C. et al. ACIE 2005, 44, 4442.

<Mechanism>

details depend on R-X and HNu.

17.8. Copolymerization of CO and Olefins
RPd cat.
RO

similar conditioins of hyroesterificationin the absence of acid co-catalyst
weakly nucleophilic alcohol or aprotic solvent is preferred.

+ COn<Mechanism>

OCO + ethylene

PLL

CO

bidentate ligand(dppp) is favored.

Pd
CO
P = polymer

COOL

L

PPd

L
resting state
at high P COOCOPdPL

L

OPdL
resting state
at low PCO
Origin of perfect alterationP

rate-determining
stepCOCatalyst decomposition[Pd] = Pd(dppp)+or generation ofPd(0) metalfrom Pd hydrideunfavorable
CO insertion into M-acyl bond is thermodynamically unfavorable.
Chain Termination
presence of ROH

absence of ROH

still active cat.
still active cat.

still active cat.

CO + -olefin
chiral Box
Pd cat.
R

depends on ligand
and reaction conditions+ CObipy
1,10-phen

CO + styrenevery highregioselectivity
CO + aliphatic olefin

Pd-BINAPHOS cat.

4

:

1

isotactic
copolymer
Pd-BINAPHOS cat.

reversed regiochemistrycompered to styrene,
but usually not high degreeketal is final product.

17.9. Pauson-Khand Reactions (PKR)
metal reagent
or catalyst++ CO

additive effectdiscovered in eary 1970s
typical conditions:stoichiometric Co2(CO)8O(also see Oisaki's handout, chapter 5)
M(CO)xR3N-O
R3N
O(CO)x-1M
OM(CO)x-1(NR3) + CO2
effective only tointramolecular PKR

catalytic conditions

Cp2Ti(CO)2, Rux(CO)y, [Rh(CO)2Cl]2, Fe, Pd,
Ir(cod)Cl(PPh3), Mo(dmf)3(CO)3, W(CO)5(thf)also showed catalytic activity.
* Co2(CO)8 is thermally unstable
Catalytic asymmetric PKR

is also active.

Intermolecular PKR : difficult to control the regioselectivity
Kraft et al.

Yoshida & Itami et al.

chelating auxiliary is the choice.

Application in Total Synthesis
Jamison & Schreiber et al.: synthesis of (+)-epoxydictymene

Nicholas rxn

PKR<Mechanism> Magnus, P. et al. TL 1985, 26, 4851.
totally irreversibe in the presence of COslow