Palladium-Catalyzed Carbonylative Coupling and C–H Activation - New Trends in Cross-Coupling: Theory and Applications - page 484

O

Pd Cl 2 (4 mol% )
PP h 3 (4 mol%)
NEt 3 (2.4 equ iv)
CO (5 bar), 120 o C
benzene, 1 5-20 h

O

I

R

O

12 examples
38-81 %

O

R

O

O

R

Scheme 10.6 Pd-catalysed carbonylative cross-coupling of aryl iodides with cyclic
olefins.

R 2

R 1

O

Pd (OAc) 2 (5 mol%)
DPPB (5 mol%)
DiP EA (1.3 equiv )
CO (20 bar) , 100 °C
benzene, 20 h

O

I

R 1 R 2

11 examples
23-9 1%

R 3

R 3 R 2 R OH

R 1 O

O

R

R

R 3

Scheme 10.7 Pd-catalysed carbonylative coupling of o-iodophenols with allenes.

O

Pd 2 (dba) 3 .CHCl 3 (2 mol%)
DP PB ( 2 m ol%)
DiPEA (2 equiv)
CO (5 bar ), 90 °C
BMIM.PF 6 ,20h

I

R 1 R 2

R 1 17 examples

21-90%

R 2

R 3

R NH 2

H

R

R 3

Scheme 10.8 Pd-catalysed carbonylative coupling of o-iodoanilines with allenes.

In 1997, allenes, as a special family of alkenes, were employed in palladium-
catalysed carbonylative reactions with o-iodophenols by Okuro and Alper. 11
Since the reaction was highly regioselective, only a single benzopyranone
isomer was obtained in good yield (Scheme 10.7). In the same year, Grigg and
Pratt reported another carbonylative cascade reaction. Starting from
2-methallyliodobenzene, allenes were incorporated during the cascade. 12
Similarly to their previous work, Alper's group also described a palladium-
catalysed carbonylative coupling of o-iodoanilines with allenes. 13 Con-
sequently, they synthesized quinolinones in moderate to good yields under a
low pressure of CO (5 bar) (Scheme 10.8). Here, an ionic liquid was used as the
solvent and promoter to enhance the eciency of the cyclization protocol.
Interestingly, the recyclability of the system was also demonstrated.
In 1999, Iwasawa and Satoh reported a new Heck-type coupling for the
synthesis of 4,5-didehydrotropone-Co 2 (CO) 4 dppm complexes. 14 The pal-
ladium-catalysed carbonylation was promoted by a diphenylacetylene-cobalt
complex (A), furnishing the desired complexes in high yields (Scheme 10.9).
In the same year, an enantioselective palladium-catalysed intramolecular
carbonylative coupling of aryl and alkenyl triflates was reported by Hayashi
et al. 15 Based on a Pd(TFA) 2 /(S)-BINAP catalyst system, asymmetric carbo-
nylative cyclization of prochiral o-allylaryl triflates and 2-allylalkenyl triflates