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MeO
MeO
MeO
O
O
O
N
Pd
N
Pd
N
Pd
I
MeO
MeO
MeO
I
OA c
O
O
A
O
O
AgClO
4
CO OH
CO OH
MeO
O
CO
2
Me
CO
2
Me
I
CO
2
Me
N
Pd
MeO
A(10mol%)
AgClO
4
Me
2
CO, r.t.
ca
t
a
l
yt
i
c
p
r
oces
s
O
O
Scheme 9.69 The first proven case of a Pd(II)/Pd(IV) Heck reaction.
I
Z
Cu
2
O(10mol%)
Me
4
NBr, DMF
1 20°C, 30 h
Z
+
R
Z=COOR,Ph
R
Scheme 9.70 Copper-catalysed arylation of olefins.
salts catalyse the arylation of olefins by aryl iodides.
250
Subsequently, evi-
dence on Heck-like reactions using derivatives of Ru, Rh, Cu, Ni, Fe and
some other metals occasionally appeared. The chemistry was comprehen-
sively reviewed fairly recently,
251
so here we cite only a few more recent
interesting additions.
Probably the most interesting other metal is copper, because copper-
catalysed reactions are steadily advancing as a strong competitor for pal-
ladium in C-C and C-heteroatom cross-coupling reactions,
252
the develop-
ment of which, as was stated in the Introduction, is in parallel with the
development of Heck chemistry.
Heck reactions using copper precatalysts are indeed known, although the
data published are sparse and the results are so irregular that no trends can
be identified. In most cases, copper catalysts are effective only in simple
reactions between iodoarenes and standard olefins. The systems lack spe-
cific ancillary ligands and often use heterogeneous supported pre-
catalysts.
253
Arylation of acrylates by aryl iodides can be performed in the
presence of CuI (10 mol%, K
2
CO
3
) in molten PEG-3400 with microwave
heating at 180 1C.
254
Copper(I) oxide was recently shown to effect the
Mizoroki-Heck reaction of aryl iodides with standard olefins.
255
The re-
actions were run under conditions closely similar to those used in regular
Pd-catalysed Mizoroki-Heck reactions, but with a serious and highly in-
triguing difference - copper-catalysed reactions run well in the absence of
base, which was successfully replaced with inert Me
4
NBr salt (Scheme 9.70).
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