Chemistry Reference
In-Depth Information
Me
Me
PEPPSI-IPr
CO, Cs
2
CO
3
O
+
I
(HO)
2
B
Me
Me
4.5
4.6
Scheme 4.6
O
3
-(C
3
H
5
)PdCl]
2
,
KF, CO
[
η
I
CHO
CHO
+
SiF
2
Et
S
S
4.7
4.8
4.9
Scheme 4.7
I
O
OMe
(MeCN)
2
PdCl
2
, CO
Al
i
-Bu
2
PhLi
i
-Bu
2
AlCl
OMe
4.10
4.11
Scheme 4.8
O
MeO
OMe
Ph
2
Zn, CO,
NiCl
2
, MgBr
2
, L
OTf
Ph
L =
N
N
4.12
4.13
4.14
Scheme 4.9
A route to flavonones
4.16
involves the carbonylative coupling of alkynes to
o
-iodophenols or their
corresponding acetates
4.15
, with
in situ
cyclization (Scheme 4.10).
10
The carbonylative coupling of an alkynyl zinc reagent
4.18
with a highly substituted, electron-rich aryl
iodide
4.17
was used in a short synthesis of luteolin
4.20
, a flavanoid natural product (Scheme 4.11). After
the coupling, employing the PEPPSI catalyst, selective
ortho
-deprotection and 6-
endo
cyclization yielded the
natural product.
11
A carbonylative coupling of an aryl iodide
4.21
and a stannane
4.22
was employed in a synthesis of
strychnine
4.24
(Scheme 4.12).
12
Further steps employed in the synthesis of the stannane
4.22
can be found
in Chapter 2, Scheme 2.58 and Chapter 9, Scheme 9.53.
Carbonylative coupling was employed twice in a synthesis of capnellene
4.25
(Scheme 4.13) using an iter-
ative sequence to establish multiple fused cyclpentane rings.
13
Carbonylative coupling of a vinyl triflate
4.26
with vinyl stannane
4.27
gave divinyl ketone
4.28
. Such compounds are substrates for Nazarov cyclization, a
reaction promoted by the presence of the silyl group. Desilylation during the Nazarov reaction generates the
cyclopentenone
4.29
. Reduction of the alkene and formation of a new vinyl triflate
4.30
by sulfonylation of a
