Palladium-Catalyzed Carbonylative Coupling and C–H Activation - New Trends in Cross-Coupling: Theory and Applications - page 500

O

PdCl 2 (PPh 3 ) 2 (3 mo l%)
K 2 CO 3 ,anisole
CO (1 b ar), 80 °C

I

B(OH) 2

9 examples
63-89 %

R'

R R'

R

O

B(OH) 2

Br

78%

OMOM

OMOM

Scheme 10.50 Pd-catalysed carbonylative Suzuki coupling of aryl iodides with

arylboronic acids.

tert -Bu Li
BEt 3

PdCl 2 (PPh 3 ) 2
CO (15 bar)
60-90 °C, THF
RX

O

BEt 3 - Li +

14 examples
20-80%
X=I,Br,OTf

N

N

N R

Scheme 10.51 Pd-catalysed synthesis of indol-2-yl ketones.

O

Pd(PPh 3 ) 4 (0.5 mol%)
K 2 CO 3 ,DME,RT
CO (1 bar)

B(OH) 2

15 examples
77-8 8%

R'

R'PhI + X -

R

X=BF 4 -

R

Scheme 10.52 Pd-catalysed carbonylative Suzuki coupling of arylboronic acids with
hypervalent iodonium salts.

X

O

Pd(OAc) 2 (5 mol%)
PPh 3 (10 mol%)
NEt 3 , toluene
CO (1 bar)

6examples
45-95%
X=I,Br

NaBPh 4

Scheme 10.53 Pd-catalysed carbonylative synthesis of steroidal ketones.

yield (Scheme 10.51). 63 In 1998, Kang et al. used hypervalent iodonium salts
instead of aryl halides to couple organoboronic acids in the presence of CO
to obtain unsymmetric aromatic ketones. 64 Moderate yields were achieved in
the carbonylation of arylboronic acids with aryl-, alkenyl- and alkynyliodo-
nium salts at room temperature under 1 bar of CO (Scheme 10.52). Starting
from aryl trifluoroborates Xia and Chen were able to extend this method-
ology using Pd(OAc) 2 as precursor. 65
Steroidal phenyl ketones were synthesized by Skoda-Foldes et al. via a
related carbonylation pathway. 66 The ketones were produced in high yields
by carbonylation of 17-iodo-androst-16-ene derivatives in the presence of
NaBPh 4 (Scheme 10.53). Alkenyl bromides or enol triflates gave lower yields
under the same reaction conditions.