Chemistry Reference
In-Depth Information
X
R'
R'
R
R
35
(1 mol%)
R
+
THF / toluene, RT
R''
R'
ZnBr
R''
X=Cl,Br,OTf
n = normal
r = rear ranged
R''
Cl
Cl
Bo c
N
O
NN
O
CH O
O
BocN
Cl
Pd
Cl
X = Br: 99%
n/r: 99/1
X=OTf:96%
n/r: 99/1
X = Cl: 68%
n/r: 17/1
N
COO H
O
Cl
Me O
35
N
N
O
OH
F
X = Cl: 96%
n/r: 99/1
X=Cl:88%
n/r: 99/1
[Pd(IPent
Cl
)(PEPPSI)] (35) for the selective cross-coupling of secondary
organozinc reagents.
Scheme 4.20
OMe
OMe
Ph
Ph
Ph
Ph
N
N
MeO
2
C-C
4
H
8
ZnBr.LiCl
[
Pd(IPent)(PEPPSI)] (
4
)(10mol%)
B
B
N
N
N
N
TH F , R T, 12 h
Br
COOMe
50 %
Scheme 4.21 Preparation of a subporphyrin by Negishi coupling using [Pd(IPent)
(PEPPSI)] (4).
4.3.1.2.2 Applications. The catalysts developed by Organ's group have
found a number of applications in the literature in recent years. Notably,
Osuka and co-workers reported the use of [Pd(IPent)(PEPPSI)] (4) for the
meso fabrication of a subporphyrin (Scheme 4.21).
85
Another example was reported by the same group, using [Pd(IPr)(PEPPSI)]
(15) to prepare a library of 2-aryl-3-trifluoromethylnaphthofurans
(Scheme 4.22).
86
These are important compounds found in biologically ac-
tive molecules and in organic functional materials. SMe groups were used as
pseudohalides in the reaction and were coupled to ArZnCl.LiCl derivatives.
The use of SMe groups in this case required a large amount of palladium (15
mol%); nevertheless, the reaction proceeded eciently to yield the desired
biaryls in good yields. The synthesized compounds were subsequently
studied for their photophysical properties.
Finally, in 2012, Kristensen and co-workers used [Pd(IPr)(PEPPSI)] (15)to
prepare a key intermediate in the total synthesis of ascididemin.
87
The
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