Chemistry Reference
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O
PdCl
2
(PPh
3
)
2
thiourea, dppp
40 °C, CO, Et
2
NH
DBU, 48h
I
14 examples
49-92 %
R'
OAc
O
R'
R
R
Scheme 10.44 Pd-catalysed carbonylative synthesis of flavones.
I
O
Pd
2
(dba)
3
/PA-Ph
DMF, DBU
MW, 30 min
X
OH
R'
17 examples
31-92 %
TMS
Pd
2
(dba)
3
/PA-Ph
DMF, DBU, CO
TBAF, MW, 30 min
O
R
R
R'
Scheme 10.45 Pd-catalysed carbonylative synthesis of flavones.
O
PdCl
2
,NEt
3
PSIL102, 110 °C
CO (1 bar)
I
10 examples
64 -96%
R'
OH
R
O
R'
R
Scheme 10.46 Pd-catalysed carbonylative synthesis of flavones in PSIL102.
NH
2
N
O
TMS
guanidine
Na
2
CO
3
CH
3
CN/
t
BuOH
80 °C
I
N
R
1
PdCl
2
(PPh
3
)
2
Cu I, NEt
3
,THF
RT, TMS-acetylene
R
1
N
R
2
N
X
R
2
X
NH
Boc
Boc
X=C,N
R
1
X
R
2
Scheme 10.47 Pd-catalysed carbonylative synthesis of meridianins.
More recently, Awuah and Capretta reported a microwave-assisted, one-
pot palladium-catalysed carbonylative Sonogashira annulation reaction.
56
Various flavones were produced in moderate to good yields (Scheme 10.45).
Yang and Alper reported another example of carbonylations of o-iodophe-
nols with terminal acetylenes to obtain flavones.
57
Their reaction proceeded
under 1 bar of CO in ionic liquids based on a phosphonium salt [PSIL102,
C
14
H
29
(C
6
H
13
)
3
)P
1
Br
] (Scheme 10.46). It should be noted that by using
PSIL102 as an ionic liquid no phosphine ligand was required.
Elegant synthetic applications of carbonylative Sonogashira reactions were
reported by M¨ller's group. For example, in 2005 they succeeded in pal-
ladium-catalysed one-pot four-component carbonylations for the synthesis
of meridianins,
58
which
are
natural
and
bioactive
compounds
(Scheme 10.47).
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