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Me
Ar
Br
Pd(dba)
2
(2 - 10 mol %) /
Ligand
NaO
t
-Bu
O
R
1
O
Ar
R
R
dioxane, 0 - 50 °C
Me
up to 70 % ee
N
N
N
N
BF
4
BF
4
Ligands
Figure 2.73 Enantioselective intramolecular oxindole synthesis using chiral NHCs.
t
-Bu
t
-Bu
I
Me
Ar
N
N
Br
Pd(dba)
2
(5 mol %)
Ligand (5 mol %)
NaO
t
-Bu
O
R
1
O
Ar
R
R
Me
Me
DME, rt
Me
R = OMe, Me
up to 99 % Yield
up to 95 % ee
Ligands
Figure 2.74 Enantioselective intramolecular oxindole synthesis using imidazolium
iodides as chiral NHC ligand precursors.
devoted to C-H activation/functionalization, and to some excellent re-
views.
234
Additionally, owing to the more dicult oxidative addition of alkyl
halides relative to aryl/vinyl halides coupled with the propensity of the re-
sulting alkyl-Pd(II) intermediate to undergo b-hydride elimination, the use
of C(sp
3
)-electrophiles has been slow to develop. Nonetheless, beginning
with groundbreaking results from the groups of Suzuki
235
and Knochel
236
and with the pioneering work in large part from Fu and co-workers,
237
this is
a rapidly developing area
238
with exciting and challenging transformations
yet to be achieved. These challenges will undoubtedly be met with intense
research efforts aimed at identifying appropriate metal catalysts and finely
tuned ligands. A more applied and practical trend that is emerging is the
development and implementation of stable preformed complexes to achieve
better eciency from cost and environmental perspectives. These trends are
discussed at length in Chapter 3.
References
1. (a) C. C. C. Johansson Seechurn, M. O. Kitching, T. J. Colacot and
V. Snieckus, Angew. Chem. Int. Ed., 2012, 51, 5062 and references
therein; (b) T. J. Colacot, Platinum Met. Rev., 2011, 55, 84; (c) Acc. Chem.
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