Palladium-Catalyzed Carbonylative Coupling and C–H Activation - New Trends in Cross-Coupling: Theory and Applications - page 485

Co 2 (CO) 4 dppm C o 2 (CO) 6

Co 2 (CO) 4 dppm

PdCl 2 (PPh 3 ) 2 (30 mol% )
Et 2 NH (30 equiv), 80 °C
DMF, A (3 equiv)

A:

I

Up to 94% yield

O

Scheme 10.9 Palladium-catalysed cyclization of 4,5-didehydrotropone-
Co 2 (CO) 4 dppm complexes via carbonylative Heck reaction.

Pd(TFA) 2 (10 mol%)
(S)-BINAP (20 mol%)
PMP (2 equiv)
CO (1 bar), MS,
Dioxane, 80 °C

O

OTf

11 examples
55-93%
32-96% ee

N

PMP:

Scheme 10.10 Palladium-catalysed intramolecular carbonylative coupling of aryl
and alkenyl triflates to give cyclopentenones.

Pd(OAc) 2 (10 mol%)
pyridine (2 equiv)
n -Bu 4 NCl (1 equiv)
DMF, 100 °C
CO (1 bar)

O

X

13 examples
45-100%

R

R

X = I, Br, OTf

Scheme 10.11 Palladium-catalysed carbonylative indanone synthesis.

proceeded to give enantiomerically enriched cyclopentenones in high yields
(Scheme 10.10).
In 2003, Gagnier and Larock discovered a general and ecient method-
ology for the synthesis of indanones and 2-cyclopentenones using o-iodos-
tyrene as the model system (Scheme 10.11). 16 In the same way, Negishi et al.
reported the synthesis of indenones from o-iodostyrene. 7c Subsequently,
they extended this methodology to dienyl triflates, iodides and bromides. All
products were isolated in good yields. Regarding the mechanism, traces of
water in the solvent may play an important role as a proton source to favour
the formation of indanones instead of indenones.
More recently, Larhed and co-workers developed a metal carbonyl-medi-
ated and microwave (MW)-supported intramolecular carbonylative coupling
reaction of o-bromostyrenes. 17 Indanones and 3-acylaminoindanones were
produced in good yields. In the presence of Pd(OAc) 2 /(t-Bu) 3 P HBF 4 with
Mo(CO) 6 as the CO source and under MW irradation, indanones were ob-
tained in 20 min from the corresponding aryl bromides and chlorides. Both
electron-withdrawing and electron-donating groups on the arene were tol-
erated, but electron-poor o-bromocinnamic acid derivatives furnished only
the corresponding lactones via a hydroxycarbonylation-Michael addition
sequence (Scheme 10.12).
In 2010, Bloome and Alexanian described a palladium-catalysed carbo-
nylative Heck-type cyclization of alkyl halides. 18 Treatment of a range of