Trans-chelating ligands in palladium-catalyzed carbonylative coupling and methoxycarbonylation of aryl halides

Article abstract of DOI:10.1016/j.jorganchem.2009.10.001

The manuscript describes the use of a trans-chelated palladium complex derived from 1,8-bis-(4-(diphenylphosphino)phenyl)anthracene (1) and p-TolPdI(TMEDA) as a precatalyst in carbonylative Suzuki coupling and methoxycarbonylation of aryl iodides and bromides. The catalyst is active in 0.01-1 mol% loading and demonstrates highly selective transformations. The selectivity is attributed to the unique structural features of the trans-chelating ligands.

Full text of DOI:10.1016/j.jorganchem.2009.10.001

Journal of Organometallic Chemistry 695 (2010) 260–266
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Trans-chelating ligands in palladium-catalyzed carbonylative coupling
and methoxycarbonylation of aryl halides
b
Luba Kaganovsky a, Dmitri Gelman a, , Karola Rueck-Braun
*
a Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
b Technische Universität Berlin, Institut für Chemie, Straße des 17, Juni 135, 10623 Berlin, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
The manuscript describes the use of a trans-chelated palladium complex derived from 1,8-bis-(4-
(diphenylphosphino)phenyl)anthracene (1) and p-TolPdI(TMEDA) as a precatalyst in carbonylative
Suzuki coupling and methoxycarbonylation of aryl iodides and bromides. The catalyst is active in
0.01–1 mol% loading and demonstrates highly selective transformations. The selectivity is attributed to
the unique structural features of the trans-chelating ligands.
Received 27 August 2009
Received in revised form 2 October 2009
Accepted 2 October 2009
Available online 12 October 2009
Ó 2009 Elsevier B.V. All rights reserved.
Keywords:
trans-Spanning
Bidentate ligands
Carbonylation
Palladium
1. Introduction
traditionally associated with the synthesis of trans-spanned spe-
cies [7]. More importantly, the planar anthracene-based scaffold
During the past few decades, enormous efforts have been de-
voted to the synthesis of transition-metal complexes as promoters
for a variety of homogeneously catalyzed transformations. To a
great extent, the recent progress in the development of efficient
and selective catalysts is dependent on the synthesis of various li-
gands possessing unique electronic and steric properties. Although
many different ligands’ families have emerged in recent years, cis-
chelating (having chelation angle below 100°) [1] and wide bite an-
gle ones (with chelation angles ranging between 100° and 160°)
[2,3] are the most commonly used, while trans-chelating ligands
that coordinate metals at the angle of over 160° receive very little
attention [4]. This is despite that several very interesting ligands
belonging to this kind were studied in the context of their coordi-
nation chemistry and potential catalytic applications and demon-
strated very unusual and fascinating properties [5].
As a part of our research program aiming the investigation of
such compounds, we became interested in studying coordination
chemistry and catalytic properties of the trans-chelating ligands
based on 1,8-bis(p-(diphenylphosphino)phenyl)anthracene (1)
(Fig. 1).
Recently we communicated on the synthesis and coordination
properties of these ligands [6]. Inter alia, we found that the rigid
all-aromatic scaffold ensures conformational stability of the result-
ing compounds and avoids multiple technical problems that are
prefers a trans-chelation mode due to the adequately remote phos-
phine groups. On the other hand, while being mainly trans-chelat-
ing, some flexibility in coordination is allowed due to a limited
rotation of the phosphine donors and phenyl rings around C–P
and C–C bonds. The ability of a ligand to adapt different coordina-
tion geometries within a certain range is an important factor in
catalysis, because it assists in stabilization of different intermedi-
ates (e.g. cis-chelated ones) that may form over the course of a cat-
alytic cycle. For example, we demonstrated that Pd(OAc)2/1 is a
highly reactive, mild and unusually selective catalyst for the palla-
dium-catalyzed Mizoroki-Heck reaction of aryl bromides with
cycloalkenes.
Herein we wish to report the continuation of our studies on the
catalytic properties of palladium complexes bearing this trans-che-
lating ligand. In particular, we will discuss Pd-catalyzed
carbonylation.
2. Results and discussion
Palladium-catalyzed carbonylative cross-coupling is a straight-
forward alternative to the classical Friedel–Crafts synthesis of dia-
ryl ketones (Scheme 1) [8,9].
This transformation can be successfully realized through the
three-component reaction of an aromatic electrophile (typically,
aryl iodides, bromides, chlorides or triflates), carbon monoxide
and an organometallic nucleophile from the standard arsenal of
the cross-coupling reagents, such as organotin [10,11], organozinc
* Corresponding author. Tel.: +972 2 6584588; fax: +972 2 6585345.
E-mail address: dgelman@chem.ch.huji.ac.il (D. Gelman).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.10.001

L. Kaganovsky et al. / Journal of Organometallic Chemistry 695 (2010) 260–266
261
TM
H
O
Ph2P
R
PPh2
R
[Pd]/Lig
X
M
R
R
CO, solvent
+
R'
R
R'
R
X = Cl, Br, I, OTf
M = Al, Si, B, Sn, etc
Scheme 1.
Fig. 1. 1,8-bis(p-(diphenylphosphino)phenyl)anthracene (1).
[12], organoaluminum [13,14], organosilicon [15,16] and organo-
boron [17–19]. Of course, the latter reagent is more attractive for
the everyday use due to its great stability, availability and long
shelf-life.
we decided to employ a well-defined complex 2 (Eq. (1)) that is
structurally related to the intermediates involved in the reaction
(step a, Scheme 2) [31].
Unfortunately, two major problems often accompany the reac-
tion: (a) relatively harsh reaction conditions and (b) relatively poor
chemoselectivity on account of the homocoupling and dehalogen-
ation. Paradoxically, both these problems are associated with the
presence of carbon monoxide. On the one hand, the oxidative addi-
tion step of catalytically active 14-electron species across carbon–
halogen bond (step a, Scheme 2) is difficult in the presence of CO
[20], so reasonable TOFs require high temperature conditions. On
the other hand, a slow, sterically troublesome CO insertion (step
b, Scheme 2) [21] opens a shortcut to the formation of homocou-
pled and/or dehalogenated by-products [11,14,15,19].
PPh2
PPh2
1
+ p-TolPdI(TMEDA)
There are several protocols which treat selectivity issues in
these reactions. For example, PdCl2/dppf/NaI system developed
by Suzuki allows selective transformation of aryl triflates and bro-
mides [18]. Additionally, Pd(OAc)2/thiourea [22] and PdCl2/PCy3
catalysts [23] were found suitable for the carbonylative coupling
of aryl iodides and heteroaryl bromides, respectively. Finally, Beller
suggested the use of Pd(OAc)2/diadmantanyl-n-butyl phosphine
combination as a general catalyst for the efficient carbonylative Su-
zuki coupling [24]. His conditions are applicable even to electron-
rich and sterically demanding aryl bromides. In this context, it
would be interesting to test whether better selectivity may be
achieved under trans-chelating ligand-assisted conditions.
Currently, our working hypothesis [6] is that unlike wide-bite
ligands that are known to accelerate reductive elimination (prod-
uct forming) step [3,25], mainly trans-chelating ligands such as
1 have an opposite effect of decelerating it [26,27]. If so, the CO-
free channel might be shut down improving the selectivity of the
reaction, possibly on account of lower TOFs, though.
The optimization of the reaction conditions initially focused the
coupling of p-iodotoluene and phenylboronic acid and revealed
that the best conversion and corresponding yield of the product
(determined based on GC analysis versus internal standard) can
be achieved when the reactants (in 1:1.5 ratio) are stirred at
90 °C under the CO atmosphere (5 bar) in the presence 1 mol% of
Pd(OAc)2/1 and K2CO3 as a base in dioxane. Under these conditions
we were able to obtain the product in ca. 90% conversion exclu-
sively into the corresponding ketone. Lower CO pressure and other
solvent/base combinations (DMF, toluene, Et3N as a reaction med-
ium, and K3PO4ꢀH2O, K3PO4, Na2CO3, Cs2CO3, Et3N as a base were
tested) led to less satisfactory results.
2
ð1Þ
The complex was prepared by mixing together the p-Tol-
PdI(TMEDA) [32] and 1 in chloroform. NMR measurements indi-
cated the product form cleanly within 1–2 h – 31P{1H} NMR
spectrum of the reaction mixture displayed a sharp singlet with
the resonance frequency of 20.4 ppm along with only minor
impurities.
The solid state structure of the product was confirmed by the X-
ray analysis [33]. As expected, complex 2 exists in almost perfect
trans-spanned form (the ORTEP view is shown in Eq. (1)).
Applying 2 instead of the in situ formed Pd(OAc)2/1 indeed
greatly improved the reproducibility, so that we were able to study
the scope of the catalyst under the developed conditions. The re-
sults of the study are summarized in Table 1.
We were able to prepare a collection of differently substituted
diaryl ketones starting from electron-rich, -neutral and -deficient
aryl iodides and arylboronic acids in different combinations. It is
worth noting that almost independently on the electronic proper-
ties of the staring materials the reactions go to completion and iso-
lated yields reasonably match the GC-based conversions, while the
formation of the homocoupled species has never been observed.
In a limited number of runs (e.g. 3e and 3j) we detected a signif-
icantly missing percentage. However, even in these cases, the dif-
ference between the GC-conversion and isolated yield originates
from the conversion of the sterically hindered starting o-bromoi-
odobenzene to form 2-bromobenzoic acid in the presence of the
trace water. Unfortunately, the virtue of trans-chelation is does
not assist in suppression of this particular side reaction.
However, the optimization series suffered from low reproduc-
ibility. Moreover, the reaction did not become more reproducible
after exclusion of ‘‘the usual suspects” such as purity of the solvent,
size and quality of the base and the stirring efficiency [28]. Then,
we speculated, that inefficient conversion of Pd(OAc)2/1 into
Pd(0)/1 at the activation stage is responsible for the inconsistent
results. This known issue is relatively sometimes seen in cross-cou-
pling reactions [29,30] but maybe more pronounced in the case of
trans-chelating ligands with large (>160°) chelation angle. There-
fore, instead of the catalyst prepared in situ from Pd(OAc)2 and 1,
The reaction of aryl bromides under the same reaction condi-
tions was slow so that higher reaction temperatures (130 °C) and
longer reaction time (24 h) were required in order to drive the
reactions to completion. For example, corresponding benzophe-
none derivatives were prepared from the electron-rich p-bromoni-
trobenzene and p-bromoacetophenone, as well as electron-neutral
p-bromotoluene in good yield (entries 3m–o, Table 1). Remarkably,
the formation of only minor (less than 3%) CO-free biaryl by-prod-
uct was detected in these runs stressing the fact that carbonylation
reactions benefit from the use of the trans-spanned catalysts.

262
L. Kaganovsky et al. / Journal of Organometallic Chemistry 695 (2010) 260–266
0.01–0.1 mol% of 2 in triethylamine in the presence of 10 equiva-
Ar-X
Ar-Ar'
lents of methanol under 5 bar of carbon monoxide is able to con-
vert aryl iodides and bromides into the corresponding methyl
esters. Aryl iodides are, naturally, more reactive and their reactions
go to completion at 90 °C over 12 h, while complete conversion of
aryl bromides is achieved after 24 h at 130 °C. No difference in
selectivity of the transformation of aryl iodides and bromides has
been observed (Table 2).
For example, electron-rich methyl- and methoxy-substituted
iodides (4a, 4c and 4e, Table 2) and bromides (4i, 4j and 4l, Table
2) form the corresponding methyl esters in high yield. Similarly,
electron-poor methyl esters bearing halo-, keto, cyano and nitro
groups (4b, 4f–h for aryl iodides; 4m for aryl bromides) and het-
eroaryl esters (4n–o, from the corresponding heteroaryl bromides)
were isolated in excellent yield as well. Remarkably, the reaction is
less sensitive to the steric properties of the starting materials than
the previously described carbonylative coupling. For example, 1,2-
diiodobenzene to form dimethyl phthalate (4d) and 1-chloro-2-
iodobenzene to form methyl 2-chlorobenzoate (4f) exhibited
excellent conversions and isolated yields. Interestingly, unpro-
tected 4-bromobenzyl alcohol (4k) can be suitable starting mate-
rial, although the reaction of 4-bromoaniline suffered from the
competitive self aminocarbonylation (4p, Table 2).
Ar'
Ar
Pd(0)L2
O
L
d.
a.
b.
O
Ar
PdII
Ar
L
L
Ar'-M
Ar
PdII
CO
PdII
L
L
Ar'
X
L
Ar'
c.
O
PdII
Ar
L
Ar'-M
L
X
Scheme 2.
The formation of the by-produced 2-bromobenzoic acid in the
entries 3e and 3j (Table 1) urged to test the applicability of the cat-
alyst 2 to other carbonylation reactions, for example, methoxy-
carbonylation of aryl halides. Although the progress recently
achieved in the field of alkoxycarbonylation of aryl halides is spec-
tacular [9,34] and relatively simple catalysts efficiently promote
the transformation of aryl iodides [35], bromides [36] and even
chlorides [30,37] into carboxylic acid derivatives under relatively
mild conditions, the quest after new catalytic systems is not over.
A brief experimentation helped us to determine optimal reac-
tion conditions for this transformation. As we found, as little as
Aryl chlorides were found inert under the described reaction
conditions.
To conclude, we demonstrated that the structurally well de-
fined complex of palladium 2 bearing the trans-chelating 1,8-
Table 1
Carbonylative Suzuki coupling of representative aryl iodidesa and bromidesb in the presence of 2 as a catalyst.
O
2 (1 mol%)
CO (5 bar)
Na2CO3, 90 oC
dioxane
X
(HO)2B
+
R'
R
R'
R
3a-o
Product (Yieldc/Conversiond)e
X = I
O
O
O
O
OMe
Cl
3a (98/99)
3b (96/99)
3c (90/99)
3d (90/99)
O
O
O
O
OMe
Br
Cl
3e (50/99)
3f (98/99)
3g (96/99)
3h (91/99)
O
O
Br
O
OMe
O2N
O2N
Cl
3i (93/99)
3j (43/99)
3k (92/99)
Product (Yieldc/Conversiond)e
O
X = Br
O
O
OMe
O2N
3m (89/99)
3n (79/99)
3o (82/99)
O
aAryl iodide (1 mmol), 2 (0.01 mmol), dioxane (5 mL), CO (5 bar), K2CO3 (2 mmol), 90 °C for 12 h. bAryl bromide (1 mmol), 2 (0.01 mmol), dioxane (5 mL), CO (5 bar), K2CO3
(2 mmol), 130 °C for 24 h. cIsolated yield of at least 95% pure compound. dDetermined by GC. eAverage of two runs.

L. Kaganovsky et al. / Journal of Organometallic Chemistry 695 (2010) 260–266
263
Table 2
Methoxycarbonylation of representative aryl iodidesa and bromidesb in the presence of 2 as a catalyst.
O
2 (0.01-0.1 mol%)
CO (5 bar)
90-130 oC, Et3N
X
OMe
R
R
4a-p
Product (Yieldc/Conversiond)e
X = I
O
O
O
O
O
OCH3
OCH3
OCH3
OCH3
OCH3
Br
MeO
NC
4a (88/99)
4b (91/99)
4c (92/99)
4d (96/99)c
O
O
O
O
MeO
OCH3
OCH3
OCH3
OCH3
O2N
Cl
4e (98/99)
4f (97/99)
4g (89/99)
4h (72/99)f
Product (Yieldc/Conversiond)e
X = Br
O
O
O
O
OCH3
HO
OCH3
OCH3
OCH3
t-Bu
MeO
4i (85/99)
4j (98/99)
4k (72/99)
4l (86/99)
O
O
O
O
OCH3
H2N
OCH3
OCH3
OCH3
O
N
MeO
N
4m (81/99)
4n (94/99)
4o (73/99)
4p (27/99)
aAryl iodide (1 mmol), 2 (10ꢂ4 mmol), Et3N (5 mL), methanol (10 mmol), CO (5 bar), 90 °C for 12 h. bAryl bromide (1 mmol), 2 (10ꢂ3 mmol), Et3N (5 mL), methanol (10 mmol),
f
CO (5 bar), 130 °C for 24 h. cIsolated yield of at least 95% pure compound. dDetermined by GC. eAverage of two runs. Contaminated with methyl p-aminobenzoate.
bis-(4-(diphenylphosphino)phenyl)anthracene (1) is a useful cata-
lyst for the selective carbonylative Suzuki coupling and methoxy-
carbonylation of aryl iodides and bromides. The trans-
coordination preference of 2 positively affects the selectivity of
the reactions, although, on account of its reactivity – relatively
harsh conditions required in order to achieve reasonable reaction
rates for aryl bromides and the lack of reactivity of 2 toward aryl
chlorides. The latter problem, however, can be at least partially
overcome by modifying the ligand to possess more electron rich
phosphines.
were listed. Spectroscopy data of the known compounds matches
with the data reported in the corresponding references.
3.1. Synthesis of 2
1,8-Bis((4-diphenylphosphino)phenyl)anthracene
(21 mg,
0.03 mmol) and (TMEDA)Pd(4-CH3C6H4)I (13.2 mg, 0.03 mmol) in
chloroform (2 ml) was stirred for 10 min at room temperature un-
der dry nitrogen. All volatiles were evaporated under reduced pres-
sure. The residue was rinsed with diethyl ether and dried in vacuo,
affording 2 as a yellow powder. 1H NMR (CDCl3) d, ppm: 8.59 (s,
1H), 8.52 (s, 1H), 8.12 (m, 6H), 8.02 (d, JH–H = 7.4 Hz, 2H), 7.73 (d,
JH–H = 9.2 Hz, 2H), 7.59 (m, 18H), 7.09 (m, 2H), 6.93 (m, 8H), 2.03
(s, 3H). 31P NMR, d, ppm: 21.4. Elemental Anal. Calc. for
C57H43IP2Pd: C, 66.91; H, 4.24. Found: C, 67.09; H, 4.38%.
3. Experimental
All chemicals were purchased from elsewhere and used with-
out further purification. 1,8-bis-(4-(diphenylphosphino)phenyl)
anthracene (1) prepared following published procedure [6]. NMR
spectra were recorded on a Bruker instrument operating at
400 MHz for proton, 100 MHz for carbons and 161 MHz for phos-
phorus. Gas chromatography analyses were performed on a Hew-
3.2. General procedure for the Pd-catalyzed carbonylative Suzuki
coupling
lett–Packard 5890 instrument with
a
FID detector and
a
The 50 ml stainless steel high pressure Parr reactor was charged
with 2 (0.01 mmol), K2CO3 (2 mmol), aryl halide (1 mmol), boronic
acid (1.5 mmol), and 3 mL of dioxane. The reactor was sealed,
purged with CO three times and pressurized to 5 bar. The resulting
mixture was stirred at the indicated temperature for indicated
time before being cooled to ambient temperature. The reaction
Hewlett–Packard 25 m ꢁ 0.2 mm i.d. Supelcowax-10 capillary col-
umn. Yields refer to isolated yields of compounds greater than 95%
purity as determined proton Nuclear Magnetic Resonance spec-
troscopy (1H NMR) analysis. Yields reported in Tables 1 and 2 are
an average of two runs. The CAS numbers of the known compound

264
L. Kaganovsky et al. / Journal of Organometallic Chemistry 695 (2010) 260–266
mixture was diluted with CH2Cl2 and washed with water three
times. The organic layer was dried over MgSO4, then filtered and
concentrated in vacuo. The product was purified by the column
chromatography on silica.
NMR, d, ppm: 193.5, 149.9, 142.4, 140.1, 134.5, 131.4, 130.5,
129.0, 123.6.
3.2.12. 3m [CAS 53689-84-2]
1H NMR (CDCl3), d, ppm: 8.38 (d, J = 8.2 Hz, 2H), 7.94 (d,
J = 8.2 Hz, 2H), 7.79 (d, J = 8.2 Hz, 2H), 7.54 (d, J = 8.2 Hz, 2H). 13C
NMR, d, ppm: 193.5, 149.9, 142.4, 140.1, 134.5, 131.4, 130.5,
129.0, 123.6.
3.2.1. 3a [CAS 119-61-9]
1H NMR (CDCl3), d, ppm: 7.87 (d, JH–H = 7.6 Hz, 4H), 7.62
(t, JH–H = 7.2 Hz, 2H), 7.51 (d, JH–H = 7.6 Hz, 4H). 13C NMR d 196.8,
137.5, 132.5, 130.3, 127.9.
3.2.13. 3n [CAS 1144-74-7]
3.2.2. 3b [CAS 643-65-2]
1H NMR (CDCl3), d, ppm: 8.36–8.34 (m, 2H), 7.95–7.93 (m, 2H),
7.80 (t, J = 4.0 Hz, 2H), 7.65 (d, J = 8 Hz, 1H), 7.53 (t, J = 8 Hz, 2H).
13C NMR, d, ppm: 194.7, 149.8, 142.9, 136.3, 133.5, 130.4, 130.1,
128.6, 123.1.
1H NMR (CDCl3) d, ppm: 7.83 (d, J = 8 Hz, 2H), 7.66 (s, 1H), 7.61
(d, JH–H = 8 Hz, 2H), 7.51 (t, J = 7.6 Hz, 2H), 7.42 (m, 2H), 2.43 (s,
3H). 13C NMR d, ppm: 196.9, 138.1, 137.7, 137.6, 133.2, 132.3,
130.4, 130.0, 129.7, 128.1, 127.3, 21.3.
3.3. General procedure for Pd-catalyzed methoxycarbonylation
3.2.3. 3c [CAS 6136-67-0]
1H NMR (CDCl3), d, ppm: 7.83 (d, J = 7.6 Hz, 2H), 7.59 (t,
J = 7.6 Hz, 1H), 7.51 (t, J = 8.4 Hz, 4H), 7.39 (m, 2H), 7.15 (dd,
J = 7.8 Hz, 1H), 3.86 (s, 3H). 13C NMR, d, ppm: 196.5, 159.6, 138.9,
137.6, 132.4, 130.0, 129.2, 128.2, 122.8, 118.8, 114.3, 55.4.
The 50 ml stainless steel high pressure Parr reactor was charged
with 2 (10ꢂ3–10ꢂ4 mmol), aryl iodide or bromide (1 mmol), meth-
anol (10 mmol), and thriethylamine (2 mL). The reactor was sealed
and pressurized with CO(g) to 5 bar. The autoclave was sealed,
purged with CO three times and pressurized to 5 bar. The resulting
mixture was stirred at the indicated temperature for indicated
time before being cooled to ambient temperature. The reaction
mixture was ediluted with CH2Cl2 and washed with sodium bicar-
bonate three times. The organic layer was dried over MgSO4, then
filtered and concentrated in vacuo. The product was purified by the
column chromatography on silica if necessary.
3.2.4. 3d [CAS 134-85-0]
1H NMR (CDCl3), d, ppm: 7.80 (t, J = 7.2 Hz, 4H), 7.63 (t,
J = 7.8 Hz, 1H), 7.52 (m, 4H). 13C NMR, d, ppm: 195.5, 138.9,
137.2, 135.8, 132.6, 131.4, 129.9, 128.6, 128.4.
3.2.5. 3e [CAS 13047-06-8]
1H NMR (CDCl3), d, ppm: 7.85 (d, J = 8 Hz, 2H), 7.68 (m, 2H), 7.50
(t, J = 7.4 Hz 2H), 7.42 (d, J = 7.6 Hz, 1H), 7.39 (t, J = 6.4 Hz 2H). 13C
NMR, d, ppm: 195.8, 140.7, 136.1, 133.7, 133.2, 131.1, 130.2, 129.0,
128.6, 127.2, 119.5.
3.3.1. 4a [CAS 99-75-2]
1H NMR (CDCl3), d, ppm: 8.00, (d, J = 8.0 Hz, 2H), 7.25 (d,
J = 8.0 Hz, 2H), 3.91 (s, 3H), 2.41 (s, 3H). 13C NMR, d, ppm: 167.2,
143.5, 129.6, 129.0, 127.4, 51.9, 21.6.
3.2.6. 3f [CAS 131-58-8]
1H NMR (CDCl3), d, ppm: 7.81 (d, J = 8 Hz, 2H), 7.76 (d, J = 8 Hz,
2H), 7.61 (t, J = 7 Hz, 1H), 7.51 (t, J = 7.6 Hz, 2H), 7.31 (d, J = 7.6 Hz,
2H), 2.46 (s, 3 H). 13C NMR, d, ppm: 196.4, 143.2, 137.9, 134.9,
133.5, 132.3, 131.2, 130.3, 129.9, 128.9, 128.2, 21.6.
3.3.2. 4b [CAS 619-42-1]
1H NMR (CDCl3), d, ppm: 7.93 (d, J = 8.9 Hz, 2H), 7.61 (d,
J = 8.9 Hz, 2H), 3.93 (s, 3H). 13C NMR, d, ppm: 166.35, 131.7,
131.1, 129.0, 128.0, 51.9.
3.2.7. 3g and 3o [CAS 85520-37-4]
1H NMR (CDCl3), d, ppm: 7.76 (d, J = 8 Hz, 2H), 7.40 (m, 3H), 7.30
(d, J = 8.3 Hz, 2H), 7.14 (d, J = 6.8 Hz, 1H), 3.86 (s, 3H), 2.45 (s, 3H).
13C NMR, d, ppm: 196.2, 159.5, 143.2, 139.2, 134.9, 130.2, 129.1,
128.9, 122.6, 118.5, 114.3, 55.4, 21.64.
3.3.3. 4c and 4j [CAS 121-98-2]
1H NMR (CDCl3), d, ppm: 8.00 (d, J = 8.6 Hz, 2H), 6.92 (d,
J = 8.6 Hz, 2H), 3.88 (s, 3H), 3.85 (s, 3H). 13C NMR, d, ppm: 166.7,
131.5, 128.1, 122.4, 113.5, 55.2, 51.7.
3.2.8. 3h [CAS 5395-79-9]
1H NMR (CDCl3), d, ppm: 7.76 (m, 4H), 7.47 (d, J = 8.3 Hz, 2H),
7.31 (d, J = 8.3 Hz, 2H), 2.46 (s, 3H). 13C NMR, d, ppm: 195.1,
143.5, 138.5, 139.2, 134.5, 131.3, 130.1, 129.1, 128.5, 21.6.
3.3.4. 4d [CAS 131-11-3]
1H NMR (CDCl3), d, ppm: 7.71 (m, 2H), 7.53 (m, 2H), 3.88 (s, 3H).
13C NMR, d, ppm: 167.9, 131.8, 131.0, 128.7, 52.5.
3.2.9. 3i [CAS 131822-45-2]
3.3.5. 4e [CAS 5368-81-0]
1H NMR (CDCl3), d, ppm: 8.33 (d, J = 7.6 Hz, 2H), 7.95 (d,
J = 8.3 Hz, 2H), 7.63 (s, 1H), 7.59 (d, J = 8.3 Hz, 1H), 7.48 (d,
J = 7 Hz, 1H), 7.433 (t, J = 7 Hz, 1H), 2.41 (s, 3H). 13C NMR, d,
ppm: 194.9, 149.7, 143.0, 138.6, 136.3, 134.2, 130.6, 130.4, 128.4,
127.4, 123.50, 21.3.
1H NMR (CDCl3), d, ppm: 7.64 (d, J = 7.1 Hz, 1H), 7.56 (s, 1H),
7.35 (t, J = 7.1 Hz, 1H), 7.11 (d, J = 8 Hz, 1H) 3.91 (s, 3H), 3.84 (s,
3H). 13C NMR, d, ppm: 166.9, 159.5, 131.4, 129.3, 121.9, 119.4,
113.9, 55.3, 52.1.
3.3.6. 4f [CAS 610-96-8]
3.2.10. 3j [CAS 890098-06-3]
1H NMR (CDCl3), d, ppm: 7.80 (d, J = 7.7 Hz, 1H), 7.43 (m, 2H),
7.29 (t, J = 7.7 Hz, 1H), 3.90 (s, 3H). 13C NMR, d, ppm: 166.0,
133.6, 132.5, 131.3, 131.0, 130.0, 126.5, 52.3.
1H NMR (CDCl3), d, ppm: 7.67 (d, J = 7.6 Hz, 1H), 7.47 (m, 2H),
7.38 (t, J = 7.6 Hz, 3H), 7.31 (m, 1H), 7.18 (d, J = 7.6 Hz, 1H), 3.87
(s, 3H). 13C NMR, d, ppm: 195.6, 159.8, 140.7, 137.4, 133.19,
131.1, 129.5, 128.9, 127.1, 123.5, 120.4, 119.5, 113.6, 55.4.
3.3.7. 4g [CAS 13531-48-1]
3.2.11. 3k [CAS 7497-60-1]
1H NMR (CDCl3), d, ppm: 8.33 (s, 1H), 8.28 (d, J = 7.2 Hz, 1H),
7.86 (d, J = 8 Hz, 1H), 7.62 (d, J = 8 Hz, 1H) 3.97 (s, 3H). 13C NMR,
d, ppm: 164.9, 135.8, 133.5, 133.1, 131.4, 129.4, 117.7, 112.9, 52.5.
1H NMR (CDCl3), d, ppm: 8.38 (d, J = 8.2 Hz, 2H), 7.94 (d,
J = 8.2 Hz, 2H), 7.79 (d, J = 8.2 Hz, 2H), 7.54 (d, J = 8.2 Hz, 2H). 13C

L. Kaganovsky et al. / Journal of Organometallic Chemistry 695 (2010) 260–266
265
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3.3.8. 4h [CAS 619-50-1]
1H NMR (CDCl3), d, ppm: 8.26 (m, 4H), 3.96 (s, 3H). 13C NMR, d,
ppm: 165.1, 150.6, 135.5, 130.7, 123.5, 52.8.
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138.1, 133.6, 133.4, 130.1, 128.2, 126.7, 52.0, 21.2.
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1H NMR (CDCl3), d, ppm: 7.87 (m, 2H), 7.38 (m, 2H), 3.91 (s, 3H),
2.41 (s, 1H). 13C NMR, d, ppm: 167.1, 146.4, 129.6, 128.9, 126.4,
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1H NMR (CDCl3) 8.00 (d, J = 8.4 Hz, 2H), 7.41 (d, J = 8.4 Hz, 2H),
3.92 (s, 3H), 1.36 (s, 9H). 13C NMR, d, ppm: 167.1, 156.5, 129.4,
127.3, 125.3, 51.9, 35.0, 31.1.
3.3.12. 4m [CAS 3609-53-8]
1H NMR (CDCl3), d, ppm: 8.12 (d, J = 8.4 Hz, 2H), 8.00 (d,
J = 8.4 Hz, 2H), 3.94 (s, 3H), 2.63 (s, 3H). 13C NMR, d, ppm: 197.5,
166.2, 140.2, 133.88, 129.8, 128.1, 52.4, 26.8.
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8.25 (d, J = 8.4 Hz, 1H), 3.91 (s, 3H). 13C NMR, d, ppm: 165.6,
153.3, 150.8, 136.9, 125.9, 123.2, 52.3.
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6.74 (d, J = 9.3 Hz, 1H), 3.96 (s, 3H), 3.88 (s, 3H). 13C NMR, d,
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1H NMR (CDCl3), d, ppm: 7.35 (m, 2H), 7.19 (d, J = 8 Hz, 1H), 6.84
(m, 1H), 3.87 (s, 3H). 13C NMR, d, ppm: 167.4, 146.9, 131.0, 129.2,
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Acknowledgement
We thank the Israel Science Foundation (Grant No. 866/06) and
the German Israeli Science Foundation for Research and Develop-
ment (Grant No. 894/05) financial support. We also thank Dr. Shm-
uel Cohen for solving X-ray structures.
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