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O
O
O
Pd(PPh
3
)
4
(10 mol%)
CsF (4.5 equiv), THF
CO (1 bar), 60 °C
S
Br
B(OH)
2
S
12 examples
33-99%
R
R
Scheme 10.59 Pd-catalysed synthesis of b-keto sulfoxides.
B(O H)
2
Pd (OAc)
2
(5 mol%)
PP h
3
(10 mol%)
CsF, THF, RT
CO (1 bar)
R
3
n
n
12 examp les
32-77 %
R
2
R
3
X
OTf
R
1
X
R
1
R
2
O
X=NR,O,S
Scheme 10.60 Pd-catalysed carbonylative coupling of enol triflates.
Pd(PPh
3
)
4
(3 mol %)
aqueous Na
2
CO
3
toluene, 110 °C
CO (1 bar)
B(O H)
2
6 examples
1 0-81%
Se
I
R
Se
R
O
Scheme 10.61 Pd-catalysed carbonylative coupling of 2-iodoselenophenes.
Pd(PPh
3
)
4
and CsF as base in the presence of 1 bar of CO (Scheme 10.59).
The carbonylative coupling reaction is strongly favoured over the competing
non-carbonylation and homocoupling processes. However, in case of boro-
nic acids carrying strongly electron-withdrawing substituents, the chemos-
electivity decreased and by-products were observed.
Occhiato and co-workers described the carbonylative coupling of lactam-,
lactone- and thiolactone-derived enol triflates with boronic acids.
74
Several
unsymmetrical dienones were formed in moderate to good yields at room
temperature under 1 bar of CO with 1-5 mol% of palladium catalyst
(Scheme 10.60). This methodology allows for a convergent and rapid prep-
aration of substrates, which are useful in conjugate additions and Nazarov
reactions.
Kollar and co-workers discussed the carbonylative coupling of 1-iodocy-
clohexene with arylboronic acids.
75
Among all the possible products, alkenyl
ketones were synthesized selectively under appropriate conditions. The
yields were strongly dependent on both the reaction conditions and the type
of arylboronic acid. Zeni and co-workers reported the coupling of 2-iodose-
lenophenes with arylboronic acids and CO in 2006 (Scheme 10.61).
76
Inter-
estingly, the reaction proceeded with aqueous Na
2
CO
3
as base under 1 bar of
CO. Concerning the type of arylboronic acids, those substituted with strong
electron-withdrawing groups and ortho-substituted arylboronic acids gave
low or no yields.
Palladium-catalysed carbonylative couplings of iodoferrocene with aryl-
boronic acids were reported by Yang and co-workers.
77
A series of aryl fer-
rocenyl ketones were prepared in good yields under mild conditions
(Scheme 10.62). Both strongly activated and ortho-substituted arylboronic
acids gave the corresponding ketones in moderate yields.
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