Synthesis of mixed N,N′-(Ar,Ar′-diaryl)iminoisoindolines for applications in palladacycle formations

Article abstract of DOI:10.1016/j.ica.2011.09.054

The synthesis of N,N′-(Ar,Ar′-diaryl)iminoisoindolines containing different aryl groups bound to the two nitrogen atoms is described. The iminoisoindolines were obtained by a three component, one-pot reaction of phthalaldehyde with 1 equivalent p-NO₂

Full text of DOI:10.1016/j.ica.2011.09.054

Inorganica Chimica Acta 379 (2011) 122–129
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Synthesis of mixed N,N0-(Ar,Ar0-diaryl)iminoisoindolines for applications
in palladacycle formations
Jackson M. Chitanda a, Shih-Chang Wu a, J. Wilson Quail b, Stephen R. Foley a,
⇑
a University of Saskatchewan, Department of Chemistry, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
b Saskatchewan Structural Sciences Centre, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
a r t i c l e i n f o
a b s t r a c t
The synthesis of N,N0-(Ar,Ar0-diaryl)iminoisoindolines containing different aryl groups bound to the two
nitrogen atoms is described. The iminoisoindolines were obtained by a three component, one-pot
reaction of phthalaldehyde with 1 equivalent p-NO2-aniline and 1 equivalent p-R-aniline, where R = H,
Me, MeO or iPr, resulting in formation of non-symmetrically substituted (mixed) iminoisoindolines,
Article history:
Received 11 May 2011
Received in revised form 23 September
2011
Accepted 26 September 2011
Available online 2 October 2011
i
1-p-nitrophenylimino-2-p-R-phenylisoindoline (R = H (1), Me (2), MeO (3), and Pr (4)), as analytically
pure precipitates requiring no further purification. Only one isomer precipitates from solution wherein
the nitro group resides exclusively at the imine position while the more electron donating substituent
ends up on the isoindoline ring position. Further reaction with Pd(OAc)2 in dichloromethane at room
temperature results in formation of six-membered [C,N] dinuclear cyclopalladated complexes with the
Keywords:
Iminoisoindoline
Isoindolinone
Diimine
general formula [(Ar,Ar0-diaryliminoisoindoline)Pd{
l-OAc}]2.
Ó 2011 Elsevier B.V. All rights reserved.
Palladacycle
1. Introduction
ple, a SciFinder structure search reveals only 19 independent
references in the last 100 years [8]. One possible reason for the
dearth of interest in diaryliminoisoindolines is simply that they
have not been found as a subunit of any natural product.
Carbon–carbon (C–C) coupling reactions are among the most
important transformations in organic synthesis. Palladium based
catalysts, in particular palladacycles, have been found to be supe-
rior catalytic systems in this regard due to their ease of prepara-
tion, air and moisture stability, low loading and high activity.
Palladacycles have been known since the 1960s but were not used
for C–C coupling reactions until 1995 and have rapidly emerged as
being among the most active catalysts known for a large variety of
coupling reactions [1,2]. There is a large diversity of palladacycles
reported in the literature, the most common of which are pallada-
cycles incorporating [C,P] and [C,N] metallacyclic formations [3].
The Pd–C bonds in palladacycles are most commonly formed by
intramolecular C–H activation in the ortho position of a proximal
aryl group to form the metal–carbon bond usually resulting in five-
or six-membered ring palladacycles. Several palladacycles are even
commercially available; most notably the diimine-based Nájera
catalyst [4], the amine-based Indolese catalyst [5] and Bedford’s
phosphite-based catalyst [6].
We recently reported the synthesis of a series of air and moisture
stable N,N0-diaryliminoisoindoline-based palladacycles (Fig. 1) [9].
The corresponding palladacycles also required only one synthetic
step and precipitate from solution as analytically pure solids. These
complexes were found to be active pre-catalysts in the activation of
aryl chlorides for the formation of biphenyls and cinnamates in the
Suzuki and the Heck coupling reactions [9]. We further reported that
with 1-p-nitrophenylimino-2-p-nitrophenylisoindoline (R = R0 =
NO2; Fig. 1), there was no reaction with palladium(II) acetate and
thus no formation of the corresponding palladacycle. This is likely
due to the electron withdrawing/deactivating effects of the nitro
substituent inhibiting both imine coordination and ortho-pallada-
tion. Intrigued by this result, we decided to investigate the synthesis
of mixed N,N0-(Ar,Ar0-diaryl)iminoisoindolines ligands containing
different aryl groups bound to the two nitrogen atoms (R – R0,
Fig. 1) wherein the aryl groups of the mixed diaryliminoisoindoline
would contain alternatively one nitro group and one neutral or
electron donating group in the para positions. Herein we report
the synthesis and characterization of a series of mixed (N,N0)-Ar,A-
r0-diaryliminoisoindolines and subsequent formation of the
corresponding air and moisture stable iminoisoindoline-based
palladacycles in a simple two-step protocol. Their applications in
Mizoroki–Heck coupling reactions were also investigated.
While N,N0-diaryliminoisoindolines were first synthesized in
1910, few applications have been found for this subclass of
indolines, either as ligands or as organic substrates [7]. For exam-
⇑
Corresponding author. Tel.: +1 306 966 2960.
E-mail address: stephen.foley@usask.ca (S.R. Foley).
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.09.054

J.M. Chitanda et al. / Inorganica Chimica Acta 379 (2011) 122–129
123
and the C@N stretching frequency in the IR spectra appears at
ꢀ1645 cmꢁ1
.
The mixed Ar,Ar0-diaryliminoisoindoline synthesis likely pro-
ceeds first via reaction of phthalaldehyde with one equivalent of
the more electron donating aniline resulting in formation of an imi-
no-aldehyde I (Scheme 1). The resulting imino-aldehyde can then
undergo a slower second condensation reaction with p-NO2-aniline
forming a transient
c-diimine II. The c-diimine then undergoes
2
intramolecular cyclization initiated by the more electron donating
imine resulting in formation of the corresponding iminoisoindoline
III with the NO2 moiety residing exclusively on the imine position.
We have previously shown that the c-diimine intermediate II can
Fig. 1. Mixed iminoisoindoline-based palladacycles where R – R0.
only be isolated providing the aryl groups are sufficiently bulky to
inhibit intramolecular cyclization [11]. A competing side reaction
also occurs where intramolecular cyclization of the transient imi-
no-aldehyde species results in formation of the corresponding iso-
indolinone IV which limits the overall yield of the mixed
iminoisoindoline ligands. The presence of the isoindolinone was
confirmedby MS analysis of the filtrate. Fortuitously, under the reac-
tion conditions employed, the isoindolinone remains in solution
while the desired iminoisoindoline precipitates out as a yellow pow-
der. The isoindolinone does not further react with ArNH2 (Scheme
1).
Unlike the diaryliminoisoindolines, the corresponding N-aryl-
isoindolinones have found widespread application in the pharma-
ceutical industry with many examples being commercially
available including the isoindolinones from Scheme 1 [12]. Recent
publications by the groups of Pan as well as Alajarín and Sánchez-
Andrada provide mechanistic details into the formation of isoind-
olinones from phthaldehyde [13,14].
When the reaction is carried out with two different anilines
both bearing electron withdrawing groups in the para position
(specifically NO2 and COMe), the resulting iminoisoindoline
precipitates as a mixture of three compounds: 1-p-nitrophenylimi-
no-2-p-acetylphenylisoindoline (A), 1-p-acetylphenylimino-2-p-
acetylphenylisoindoline (B) and 1-p-nitrophenylimino-2-p-nitro-
phenylisoindoline (C) in the ratio 17:5:1, respectively as shown
in Scheme 3 in 80% overall yield. Compounds A–C were identified
by mass spectrometry as well as 1H and 13C NMR spectroscopy.
Compounds B and C have been previously reported [9,10], while
characterization of A is herein reported. Thus it appears that in or-
der to facilitate isolation of a mixed iminoisoindoline in a one-pot
2. Results and discussion
2.1. Ligand Synthesis
As we have previously reported, the diaryliminoisoindoline,
1-p-nitrophenylimino-2-p-nitrophenylisoindoline
(R = R0 = NO2;
Fig. 1), did not react with palladium(II) acetate to form the corre-
sponding palladacycle which is likely due to the highly electron
withdrawing nature of the nitro substituents inhibiting ortho-pal-
ladation [9]. We envisioned that substitution of the nitro group
of the aryl ring bound directly to the isoindoline skeleton with
more electron donating substituents would allow for C–H activa-
tion and subsequent palladacycle formation. As with the previ-
ously reported symmetrically substituted iminoisoindolines, the
non-symmetrically substituted ligands proved remarkably easy
to synthesize. The one pot reaction of phthalaldehyde with equi-
molar amounts of p-NO2-aniline and p-R-aniline (R = H, Me, MeO
or iPr) results in successful formation of non-symmetrically substi-
i
tuted iminoisoindoline ligands (R = H (1), Me (2), MeO (3), and Pr
(4)) in 40–55% yield as shown in Schemes 1 and 2. In all cases, the
nitro group resides exclusively at the imine position while the
more electron donating substituent ends up on the isoindoline ring
position. The desired compounds precipitated out of solution as
analytically pure solids. The mixed iminoisoindolines are all previ-
ously unreported except for 3 [10]. Compounds 1–4 were charac-
terized by 1H and 13C NMR, mass spectrometry, elemental
analysis and IR spectroscopy. 1H NMR spectra show a characteristic
singlet for the CH2 moiety of the isoindoline ring of 1–4 at ꢀ5 ppm
NH2
CHO
CHO
R
O
R = H, Me, OMe, iPr
N
R
NH2
O2N
O2N
O2N
ArNH2
O
N
N
N
R
N
N
R
R
Scheme 1. Synthesis of mixed Ar,Ar0-diaryliminoisoindolines.

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J.M. Chitanda et al. / Inorganica Chimica Acta 379 (2011) 122–129
2
2
2
2
i
O2N
2
O
Me
R
O
i
Scheme 2. Preparation of mixed-iminoisoindoline ligands and their corresponding palladacycles. (i) methanol:ether (1:1) as solvent, formic acid, room temperature, 12 h. (ii)
CH2Cl2 as solvent, room temperature, 12 h.
Scheme 3. Synthesis of mixed iminoisoindoline ligands from two substituted anilines which both contain electron withdrawing groups. (i) Methanol:ether (1:1) as solvent,
formic acid, room temperature, 12 h.
synthesis, a significant difference in the electron donating ability of
the two para-substituted anilines must be employed, consistent
with the proposed mechanism in Scheme 1.
Elemental analyses for all complexes indicate the presence of the
anion acetate in the structure.
Dinuclear palladacycles in which the two palladium centers are
linked by two bridging acetato groups can exhibit anti- and
syn-conformations [9,15]. In this case, NMR data allows for easy
differentiation between the anti- and syn-conformations where
the anti-isomer exhibits overall C2 symmetry and the syn-isomer
is Cs symmetric. A characteristic indication of cyclopalladation in
complexes 5–8 is the observed 1H NMR resonance for the CH2 pro-
tons of the iminoisoindoline ring. The ligands (1–4) show a singlet
corresponding to the two methylene protons at ꢀ5 ppm. Upon
cyclopalladation, these methylene protons become diastereotopic
in the anti-isomer resulting in formation of two doublets at ꢀ4.6
and ꢀ3.5 ppm, where each doublet corresponds to one proton
per ligand. In all four complexes only the anti-isomers were ob-
tained due to steric effects. The ESI-Q-TOF mass spectra of com-
plexes 5–8 all showed a distinct signal which was assigned to
their respective molecular cation [MꢁOAc]+.
2.2. Synthesis of [(mixed-iminoisoindoline)Pd{-OAc}]2 palladacycles
Reaction of Pd(OAc)2 in dichloromethane at room temperature,
with one equivalent of the respective mixed-iminoisoindoline 1–4
resulted in formation of acetato-bridged, dinuclear palladacyclic
complexes 5–8 as analytically pure yellow solids of the general for-
mula, [(iminoisoindoline)Pd(l-OAc)]2 (Scheme 2). As mentioned
earlier, no palladacycle was obtained from reaction of 1-p-nitro-
phenylimino-2-p-nitrophenylisoindoline (C) and Pd(OAc)2. Substi-
tution of one nitro group on the ring position of C with a more
electron donating substituent results in successful formation of
air and moisture stable mixed-iminoisoindoline palladacycles 5–8.
Palladacycles 5–8 were characterized by IR and NMR spectros-
copy, mass spectrometry and elemental analysis. Crystal structures
were also obtained for all palladacycles to further confirm the
coordination environment around the metal centers.
X-ray diffraction studies were undertaken and the crystal
structures of palladacycles 5–8 were determined. Complex 5 co-crys-
tallized with one molecule of chloroform, the solvent of crystalliza-
tion, while 6 had two unsymmetrical molecules along with water
and dichloromethane in the unit cell. This latter complex was crystal-
lized under air from dichloromethane which had not been previously
In the IR spectra of complexes 5–8, the signals for the C@N bond
vibrations were shifted to lower wavenumber compared to those
of the free iminoisoindoline (
formation of a Pd–N bond in the cyclopalladated complexes.
D
k ꢀ 35 cmꢁ1) consistent with the

J.M. Chitanda et al. / Inorganica Chimica Acta 379 (2011) 122–129
125
dried. As expected, all four complexes crystallized exclusively as the
anti-isomers, unambiguously confirming the presence of six-mem-
bered [C,N] palladacycles. Anti-configurations are also observed in
the crystal structures of most previously reported acetato-bridged
dinuclear palladacycles [10]. The two palladium atoms are bridged
by two acetate ligands with each palladium center having a chelating
[C,N]-bound iminoisoindoline ligand forming the palladacycle. The
dinuclear acetato-bridged complexes adopt a characteristic closed-
book conformation where the two [C,N]-bound iminoisoindoline li-
gands stack on top of one another. As expected, the coordination
geometry about the palladium atoms in all four structures is approx-
imately square planar with the sum of the angles around the palla-
dium atoms for all four complexes being 360 1°. The Pd–Pd
distances were found to be 3.1109(6) Å for 5, 2.9856(6) Å for 6,
3.0449(6) Å for 7 and 3.0453(4) Å for 8 which are consistent with pre-
viously reported acetato-bridged dinuclear palladacycles [10]. The
Pd–C and Pd–N bond lengths of complexes 5–8 were all essentially
identical (within esd) at 1.97(1) Å and 2.01(1) Å, respectively. The
Pd–O distances of the two acetate ligands differ by about 0.10 Å for
5–8 (for example, in 6, Pd(1)–O(1) is 2.137 Å while Pd(1)–O(3) is
2.063 Å), indicative of the stronger trans-influence of the metallated
carbon compared to that of the imine nitrogen.
ORTEP plots for 5–8 are shown in Figs. 2–5 with bond distances
and angles indicated in their respective captions. Crystallographic
data and refinement parameters are summarized in Table 1.
2.3. Applications of [(mixed-iminoisoindoline)Pd{-OAc}]2
palladacycles in Mizoroki–Heck coupling reactions
Fig. 3. ORTEP plot of 6 (view of molecule B) at the 30% probability level. Hydrogen
atoms, molecule A and solvent molecules have been omitted for clarity. Selected
bond lengths [Å] and angles [°]: Pd(1B)–C(10B) = 1.968(6), Pd(1B)–N(2B) = 2.004(5),
Pd(1B)–O(3B) = 2.058(4), Pd(1B)–O(1B) = 2.140(4), Pd(1B)ꢂꢂꢂPd(2B) = 2.9856(6),
C(10B)–Pd(1B)–N(2B) = 89.0(2), C(10B)–Pd(1B)-O(3B) = 91.5(2), N(2B)–Pd(1B)–
We have previously shown that (diaryliminoisoindoline)Pd{l-
OAc}]2 palladacycles bearing electron-donating aryl groups are
effective pre-catalysts in the activation of aryl chlorides for the for-
mation of biphenyls and cinnamates in the Suzuki–Miyaura and
the Mizoroki–Heck coupling reactions [9]. For example, in the Heck
O(5B) = 178.25(18),
85.62(17).
N(2B)–Pd(1B)–O(1B) = 93.70(18),
O(3B)–Pd(1B)–O(1B) =
Fig. 2. ORTEP plot of 5 at the 50% probability level. The hydrogen atoms and CHCl3 molecule have been omitted for clarity. Selected bond lengths [Å] and angles [°]: Pd(1)–
C(10) = 1.967(6), Pd(1)–N(2) = 2.006(5), Pd(1)–O(3) = 2.063(5), Pd(1)–O(1) = 2.138(4), Pd(1)ꢂꢂꢂPd(2) = 3.1109(6), C(10)–Pd(1)–N(2) = 89.6(2), C(10)-Pd(1)–O(3) = 90.6(2),
N(2)–Pd(1)–O(1) = 94.05(19), N(2)–Pd(1)–O(3) = 179.34(18), O(3)–Pd(1)–O(1) = 85.75(18).

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J.M. Chitanda et al. / Inorganica Chimica Acta 379 (2011) 122–129
Fig. 4. ORTEP plot of 7 at the 50% probability level. The hydrogen atoms have been omitted for clarity. Selected bond lengths [Å] and angles [°]: Pd(1)–C(10) = 1.974(6), Pd(1)–
N(2) = 2.011(5), Pd(1)–O(3) = 2.060(4), Pd(1)–O(1) = 2.137(4), C(10)–Pd(1)–N(2) = 89.7(2), C(10)–Pd(1)–O(3) = 91.5(2), N(2)–Pd(1)-
Pd(1)ꢂꢂꢂPd(2) = 3.0444(9),
O(1) = 95.89(17), N(2)–Pd(1)–O(3) = 178.48(18), O(3)–Pd(1)–O(1) = 82.99(17).
We were interested in investigating the effect of incorporating a
more electron withdrawing aryl group on the imino nitrogen posi-
tion of the iminoisoindoline anticipating that weakening the N–Pd
bond might lead to a more active a catalyst. On the other hand, this
could also lead to an increased rate of catalyst decomposition.
Unfortunately, it is the latter case which dominates catalytic activ-
ity with yields of only 15% exhibited for palladacycles 5 and 8 using
p-chlorobenzaldehyde under the same conditions as stated above
along with rapid precipitation of palladium black (Scheme 4).
The activity for the analogous Mizoroki–Heck reaction with bro-
mobenzaldehyde yielded turnover numbers of only 35. Repeating
the reactions at 80 °C resulted in no observable coupling product.
3. Conclusion
N,N0-(Ar,Ar0-diaryl)iminoisoindolines containing different aryl
groups on the two nitrogen atoms were obtained by a three-compo-
nent, one-pot reaction from inexpensive, commercially available
starting materials. The aryl groups were chosen to maximize the dif-
ference in electron donating character of the substituents. This not
only favors formation of the desired mixed iminoisoindolines,
wherein the more electron withdrawing substituted aryl groups re-
side exclusively on the imine position, but promotes Caryl–H activa-
tion to form air and moisture stable palladacyclic complexes in a
simple two step reaction. This is in contrast to the electron-poor imi-
noisoindoline, 1-p-nitrophenylimino-2-p-nitrophenylisoindoline,
which does not undergo ortho-palladation.
4. Experimental
Fig. 5. ORTEP plot of 8 at the 30% probability level. The hydrogen atoms have been
omitted for clarity. Selected bond lengths [Å] and angles [°]: Pd(1)–C(10) = 1.964(4),
Pd(1)–N(2) = 2.012(3), Pd(1)–O(3) = 2.057(3), Pd(1)–O(1) = 2.133(3), Pd(1)ꢂꢂꢂPd(2) =
3.0453(3), C(10)–Pd(1)–N(2) = 89.92(15), C(10)–Pd(1)–O(3) = 90.29(14), N(2)–
Unless otherwise stated, all reactions were performed under N2
using standard Schlenk techniques or in a N2-filled drybox. 1H and
13C {1H} NMR spectra were recorded on a Bruker 500 MHz Avance
spectrometer. Chemical shifts for 1H and 13C NMR are reported in
ppm in reference to the residual 1H and 13C resonances of CDCl3
(1H: d 7.24; 13C: d 77.23). Coupling constants are given in Hz.
Elemental analyses were performed on a Perkin–Elmer 2400 CHN
elemental analyzer. High resolution mass spectra (HRMS) were
measured on an Applied Biosystem QSTARÒ XL MS/MS system
(ESI-QTOF). Pd(OAc)2 was purchased from PMO Pty Ltd, Australia.
Pd(1)–O(5) = 178.18(14),
86.50(12).
N(2)–Pd(1)–O(1) = 93.11(12),
O(3)–Pd(1)–O(1) =
reaction, using 1 mol% of catalyst in the presence of 2 equivalents
of Cs2CO3 as base in DMA at 145 °C, the coupling of p-chlorobenz-
aldehyde with butylacrylate produced the corresponding
cinnamate in up to 60% yields, while the analogous reaction with
p-bromobenzaldehyde yields turnover numbers of up to 1000.

J.M. Chitanda et al. / Inorganica Chimica Acta 379 (2011) 122–129
127
Table 1
Crystal data and refinement parameters for complexes 5ꢂCHCl3, 6ꢂ1.5H2Oꢂ0.75CH2Cl2, 7 and 8.
5ꢂCHCl3
44H35Cl3N6O8Pd2
6ꢂ1.5H2Oꢂ0.75CH2Cl2
C187H170Cl6N24O38Pd8
4425.37
yellow
7
8
Formula
Formula weight
Color
C
C46H38N6O10Pd2
1047.62
orange
C50H46N6O8Pd2
1071.77
yellow
0.20 ꢃ 0.18 ꢃ 0.10
Monoclinic
P21/c
12.7855(2)
17.2702(4)
23.0660(5)
90
120.0295(14)
90
1106.94
pale yellow
0.12 ꢃ 0.10 ꢃ 0.09
Triclinic
Crystal size (mm3)
Crystal system
Space group
a (Å)
0.12 ꢃ 0.10 ꢃ 0.10
0.15 ꢃ 0.13 ꢃ 0.05
Orthorhombic
Tetragonal
ꢀ
P21 21 2
20.4831(3)
21.2390(3)
23.8327(3)
90
90
90
P41 21 2
9.2363(13)
9.2363(13)
47.882(10)
90
90
90
P1
11.7500(4)
12.0285(6)
17.2210(8)
107.308(2)
109.238(3)
91.590(3)
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
Z
2
2
4
4
qcalc (Mgmꢁ3
T (K)
)
1.692
173(2)
1.418
173(2)
1.704
173(2)
1.429
173(2)
Collected/individual reflections
Rint
27459/7655
0.1114
101049/18295
0.0890
27158/3605
0.1095
47210/9856
0.0947
F(000)
h Range (°)
Final R1 (I > 2
1108
4468
2.20–25.03
R1 = 0.0444, wR2 = 0.1032
R1 = 0.0526, wR2 = 0.1077
2112
1.70–25.03
R1 = 0.0477, wR2 = 0.0956
R1 = 0.0634, wR2 = 0.1142
2176
2.16–26.10
R1 = 0.0495, wR2 = 0.1182
R1 = 0.0631, wR2 = 0.1256
2.39–25.10
R1 = 0.0618, wR2 = 0.1475
R1 = 0.0861, wR2 = 0.1652
rI)
R1 (all data)
O
HOC
5
8 (1%)
or
H
CO2Bu
+
Cs2CO3, DMA
145 oC
Cl
CO2Bu
Scheme 4. Mizoroki–Heck cross-coupling of p-chlorobenzaldehyde with butyl acrylate.
Aniline, p-toluidine, p-anisidine and p-isopropylaniline were pur-
chased from the Sigma–Aldrich Chemical Company and used as re-
ceived except for aniline which was distilled prior to use.
Phthalaldehyde was purchased from Alfa Aesar and used as
received.
4.1.2. 1-p-Nitrophenylimino-2-p-methylphenylisoindoline (2)
Compound 2 was obtained as a yellow powder in 55% yield
(711 mg) from p-NO2-aniline (517 mg, 3.74 mmol), p-toluidine
(401 mg, 3.74 mmol) and phthalaldehyde (502 mg, 3.74 mmol). 1H
NMR (CDCl3): d 8.14 (d, J = 8.7, 2H, Ar), 7.63 (d, J = 7.7, 2H, Ar), 7.46
(m, 2H), 7.17 (m, 3H), 7.00 (d, J = 8.7, 2H), 6.95 (m, 1H), 4.99 (s, 2H,
CH2), 2.32 (s, 3H, Ar-CH3. 13C{H}NMR (CDCl3):
d
157.7
4.1. General procedure for the synthesis for ligands A and 1–4
(CC@N), 153.2(CAr), 142.6(CAr), 140.8(CAr), 138.2(CAr), 134.6(CAr),
131.7(CHAr), 131.1(CHAr), 129.9(CHAr), 127.9(CHAr), 125.8(CHAr), 1
25.4(CHAr), 123.2(CHAr), 121.9(CHAr), 121.8(CHAr), 121.3(CHAr),
54.3(CH2), 21.1 (Ar-CH3). Anal. Calc. for C21H17N3O2: C, 73.45; H,
4.99; N, 12.24. Found: C, 73.26; H, 4.69; N, 11.99%. FT-IR (KBr,
cmꢁ1): 1646 (C@N), 1612, 1584, 1512. HRMS m/z calcd. for
A Schlenk flask was charged with equimolar amounts of the cor-
responding two substituted anilines in 30 mL methanol:ether (1:1)
solvent mixture. Stoichiometric amounts of phthalaldehyde and
0.05 mL of formic acid were then added. The initially homogeneous
solution was stirred at room temperature for 12 h, over which time
the product gradually precipitated from solution. The resultant
suspension was then filtered and the precipitate washed with cold
methanol, and dried under vacuum to obtain the desired product
as a white or yellow solid.
C
21H17N3O2: 343.1321 [M], found: 342.1244 [MꢁH]+.
4.1.3. 1-p-Nitrophenylimino-2-p-methoxyphenylisoindoline (3)
Compound 3 was obtained as a yellow powder in 42% yield
(568 mg) from p-NO2-aniline (521 mg, 3.77 mmol), p-anisidine
(464 mg, 3.74 mmol) and phthalaldehyde (506 mg, 3.77 mmol). 1H
NMR (CDCl3): d 8.12 (d, J = 8.7, 2H, Ar), 7.61 (d, J = 8.3, 2H, Ar), 7.46
(m, 2H, Ar), 7.18 (m, 1H, Ar), 6.98 (m, 3H, Ar), 6.90 (d, J = 8.8, 2H,
Ar), 4.93 (s, 2H, CH2), 3.78 (s, 3H, Ar-OCH3). 13C{H}NMR (CDCl3): d
157.8 (CC@N), 157.0(CAr), 153.4(CAr), 142.5(CAr), 140.8(CAr),
133.7(CAr), 131.8(CAr), 131.1(CHAr), 127.9(CHAr), 125.8(CHAr), 125
.3(CHAr), 123.8(CHAr), 123.2(CHAr), 121.8(CHAr), 114.5(CHAr),
55.7(Ar-OCH3), 54.8(CH2). Anal. Calc. for C21H15N3O2: C, 70.18; H,
4.77; N, 11.69. Found: C, 70.25; H, 4.77; N, 11.58%. FT-IR (KBr,
cmꢁ1): 1643 (C@N), 1581, 1510, 1467. HRMS m/z calcd. for
4.1.1. 1-p-Nitrophenylimino-2-phenylisoindoline (1)
Compound 1 was obtained as a yellow powder in 47% yield
(576 mg) from p-NO2-aniline (517 mg, 3.74 mmol), aniline
(349 mg, 3.74 mmol) and phthalaldehyde (502 mg, 3.74 mmol). 1H
NMR (CDCl3): d 8.16 (d, J = 9.3, 2H, Ar), 7.80 (d, J = 7.4, 2H, Ar), 7.46
(m, 2H), 7.38 (m, 2H), 7.15 (m, 2H), 7.02 (d, J = 8.8, 2H), 6.93 (m,
1H), 4.99(s, 2H, CH2). 13C{H}NMR (CDCl3): d 157.5 (CC@N), 153.1
(CAr), 142.7(CAr), 140.8(CAr), 140.7(CAr), 131.6(CAr), 131.3(CHAr),
129.3(CHAr), 128.0(CHAr), 125.9(CHAr), 125.4(CHAr), 124.6(CHAr),
123.2(CHAr), 121.8(CHAr), 121.3(CHAr), 54.1(CH2). Anal. Calc. for
C21H15N3O2: 359.1270 [M], found: 359.1259 [M].
C
20H15N3O2: C, 72.94; H, 4.59; N, 12.76. Found: C, 72.78; H, 4.53;
N, 12.57%. FT-IR (KBr, cmꢁ1): 1654 (C@N), 1590, 1589, 1498, 1469.
HRMS m/z calcd. for C20H15N3O2: 329.1164 [M], found: 328.1096
[MꢁH]+.
4.1.4. 1-p-Nitrophenylimino-2-p-isopropylphenylisoindoline (4)
Compound 4 was obtained as a yellow powder in 42% yield
(580 mg) from p-NO2-aniline (516 mg, 3.73 mmol), p-iPr-aniline

128
J.M. Chitanda et al. / Inorganica Chimica Acta 379 (2011) 122–129
(505 mg, 3.73 mmol) and phthalaldehyde (502 mg, 3.74 mmol). 1H
NMR (CDCl3): d 8.12 (d, J = 8.4, 2H, Ar), 7.65 (d, J = 6.6, 2H, Ar), 7.46
(m, 2H), 7.20 (m, 3H), 6.99 (m, 3H), 4.96 (s, 2H, CH2), 2.88(sept,
J = 6.9, 1H, CH(CH3)2), 1.22 (d, J = 6.9, 6H, CH(CH3)2). 13C{H}NMR
152.2, (CC@N), 151.1(CAr), 145.6(CAr), 141.0(CAr), 136.9 (CHAr)
136.7(CHAr), 133.5(CAr), 133.1(CAr), 132.5(CAr), 131.7(CHAr),
130.4(CHAr), 129.1(CHAr), 128.6 (CHAr), 127.2 (CHAr), 126.5(CHAr),
126.2(CHAr), 124.8(CHAr), 123.9(CHAr), 122.6(CHAr), 121.9(CAr),
112.3(CHAr), 53.1(CH2), 24.8 (ꢁCH3, Acetate), 21.2 (Ar-CH3). Anal. Calc.
for C46H38N6O10Pd2: C, 54.40; H, 3.77; N, 8.27. Found: C, 54.37; H,
3.41; N, 8.00%; FT-IR (KBr, cmꢁ1) 1619 (C@N), 1605, 1576, 1576.
HRMS m/z calcd. for C46H38N6O8Pd2 1014.0821 [M], 957.0692
[MꢁOAc]+; found 957.0651 [MꢁOAc]+.
(CDCl3):
d 157.7 (CC@N), 153.2(CAr), 145.6(CAr), 142.6(CAr),
140.8(CAr), 138.4(CAr), 131.8(CHAr), 131.1(CHAr), 127.9(CHAr), 127
.2(CHAr), 125.8(CHAr), 125.3(CHAr), 123.2(CHAr), 121.9(CHAr),
121.8(CHAr), 54.4(CH2), 33.9 (CH(CH3)2), 24.2 (CH(CH3)2). Anal. Calc.
for C23H21N3O2: C, 74.37; H, 5.70; N, 11.31. Found: C, 73.98; H, 5.52;
N, 11.23%. FT-IR (KBr, cmꢁ1): 1642 (C@N), 1609, 1583, 1509. HRMS
m/z calcd. for C23H21N3O2: 371.1634 [M], found: 370.1544 [MꢁH]+.
4.2.3. Bis(-acetato)bis(1-p-nitrophenylimino-2-p-methoxyphenyliso
indoline)dipalladium(II) (7)
4.1.5. 1-p-Nitrophenylimino-2-p-acetylphenylisoindoline (A)
Compound A was obtained as a yellow powder in 59% yield
(820.0 mg) from p-NO2-aniline (517 mg, 3.74 mmol), p-COMe-ani-
line (506 mg, 3.74 mmol) and phthalaldehyde (502 mg,
3.74 mmol). 1H NMR (CDCl3): d 8.23 (d, J = 8.5, 2H, Ar), 8.06 (d,
J = 8.6, 2H, Ar), 8.01 (d, J = 8.6, 2H, Ar), 7.49 (m, 2H, Ar), 7.14 (m,
1H, Ar), 7.06 (d, J = 8.6, 2H, Ar), 6.81 (d, J = 7.9, 1H, Ar), 5.03 (s,
2H, CH2), 2.58 (s, 3H, –COCH3). 13C NMR (CDCl3): d 196.9 (CCOMe),
156.5 (CC@N), 152.7(CAr), 144.9(CAr), 143.0(CAr), 140.1(CAr),
132.1(CAr), 131.5(CHAr), 130.1(CAr), 129.6(CHAr), 128.0(CHAr),
126.0(CHAr), 125.5(CHAr), 123.2(CHAr), 121.2(CHAr), 118.9(CHAr),
53.1 (CH2), 26.5 (COCH3). HRMS m/z calcd. for C22H17N3O3:
371.1270 [M], found: 370.1189 [MꢁH]+.
Complex 7 was obtained as a yellow powder in 28% yield
(207 mg) from 3 (254 mg, 0.707 mmol) and Pd(OAc)2 (190 mg,
0.846 mmol). 1H NMR (CDCl3): d 8.09 (d, J = 8.0, 2H, Ar), 7.69 (d,
J = 7.7, 2H, Ar), 7.52 (m, 2H, Ar), 7.32 (d, J = 7.5, 2H, Ar), 7.17 (m,
2H, Ar), 7.10 (m, 4H, Ar), 6.62 (d, J = 8.7, 2H, Ar), 6.21 (d, J = 8.8,
2H, Ar), 5.91 (d, J = 8.5, 2H, Ar), 5.83 (d, J = 8.2, 2H, Ar), 4.61 (d,
J = 17.2, 2H, CH2), 3.22 (s, 6H, Ar-OCH3), 3.22 (d, J = 17.2, 2H,
CH2), 1.69 (s, 6H, acetate); 13C{1H} NMR (CDCl3): d 180.0(Cacetate),
154.6(CC@N), 152.2(CAr), 151.0(CAr), 145.7(CAr), 141.0 (CAr
)
131.6(CHAr), 130.5(CAr), 129.1(CAr), 128.6(CHAr), 126.4(CHAr),
125.8(CAr), 124.0(CHAr), 122.6(CHAr), 122.6(CHAr), 119.3(CHAr),
113.1(CHAr), 112.7(CHAr), 55.8(CAr-OMe), 53.2(CH2), 24.5(CMe, Acetate).
Anal. Calc. for C H38N6O10Pd2: C, 52.74; H, 3.66; N, 8.02. Found: C,
46
51.90; H, 3.59; N, 7.79%; FT-IR (KBr, cmꢁ1) 1612 (C@N), 1602,
4.2. General synthesis for palladacycles 5–8
1575. HRMS m/z calcd. for
C46H38N6O10Pd2 1046.0719 [M],
989.0590 [MꢁOAc]+; found 989.0615 [MꢁOAc]+.
A Schlenk flask was charged with equimolar amounts of iminoiso-
indoline (1–4) and Pd(OAc)2 in dichloromethane (30 mL) to form red
homogeneous solution. After12 h ofstirringatroom temperatureun-
der dinitrogen, the reaction mixture was filtered through Celite to re-
move palladium black. The filtrate was concentrated and then ether
(30 mL) added to precipitate the desired palladacycles. The resulting
precipitates of palladacycles (5–8) were filtered, washed with cold
ether (3 ꢃ 10 mL) then dried under vacuum. Crystals suitable for X-
ray diffraction studies were obtained by slow evaporation from a
50:50 dichloromethane/hexane solution under air.
4.2.4. Bis(-acetato)bis(1-p-nitrophenylimino-2-p-isopropylphenyliso
indoline)dipalladium(II) (8)
Complex 8 was obtained as a yellow powder in 29% yield
(212 mg) from 4 (254 mg, 0.684 mmol) and Pd(OAc)2 (184 mg,
0.821 mmol). 1H NMR (CDCl3): d 8.05 (d, J = 8.6, 2H, Ar), 7.62 (d, J
= 8.8, 2H, Ar), 7.53(m, 2H, Ar), 7.47 (s, 2H, Ar), 7.27 (d, J = 7.5, 2H,
Ar), 7.11 (m, 2H, Ar), 7.05 (d, J = 8.6, 2H, Ar), 6.95 (d, J = 8.2, 2H, Ar),
6.22 (d, J = 8.2, 2H, Ar), 5.82 (m, 4H, Ar), 4.54 (d, J = 17.3, 2H, CH2),
2.95 (sept, J = 6.9, 2H, CH(CH3)2), 2.90 (d, J = 17.3, 2H, CH2), 1.73 (s,
6H, acetate), 1.36 (d, J = 6.9, 6H, CH(CH3)2), 1.34 (d, J = 6.9, 6H, CH
(CH3)2); 13C{1H} NMR (CDCl3): d 180.1 (Cacetate), 152.1, (CC@N),
151.3(CAr), 145.6(CAr), 143.9(CAr), 141.2(CAr), 134.2(CHAr), 133
.8(CAr), 131.7(CHAr), 130.4(CAr), 129.0(CHAr), 128.6(CHAr),
127.0(CHAr), 126.5(CHAr), 124.7(CHAr), 124.2(CAr), 124.0(CHAr), 122
.8(CHAr), 122.8(CHAr), 112.3(CHAr), 52.9(CH2), 34.1(CH(CH3)2),
24.8(–CH3, acetate), 24.6(CH(CH3)2), 24.5(CH(CH3)2). Anal. Calc. for
4.2.1. Bis(-acetato)bis(1-p-nitrophenylimino-2-phenylisoindoline)
dipalladium(II) (5)
Complex 5 was obtained as a yellow powder in 27% yield
(205 mg) from 1 (252 mg, 0.765 mmol) and Pd(OAc)2 (206 mg,
0.918 mmol). 1H NMR (CDCl3): d 8.08 (d, J = 8.4, 2H, Ar), 7.68 (d,
J = 7.1, 2H, Ar), 7.55 (m, 4H, Ar), 7.35 (d, J = 7.5, 2H, Ar), 7.05 (m,
8H, Ar), 6.26 (d, J = 7.3, 2H, Ar), 5.79 (m, 8H, Ar), 4.65 (d, J = 17.2,
2H, CH2), 3.27 (d, J = 17.2, 2H, CH2), 1.66 (s, 6H, acetate); 13C{1H}
C
50H46N6O8Pd2: C, 56.03; H, 4.33; N, 7.84. Found: C, 55.65; H, 4.29;
N, 7.93%; FT-IR (KBr, cmꢁ1) 1614 (C@N), 1604, 1575, 1514. HRMS
m/z calcd. for C50H46N6O8Pd2 1070.1447 [M], 1013.1318 [MꢁOAc]+;
found 1013.1316 [MꢁOAc]+.
NMR (CDCl3):
145.7(CAr), 141.0(CAr), 136.7 (CAr
d
180.1 (Cacetate), 152.0, (CC@N), 151.4(CAr),
136.7(CHAr), 135.7(CAr),
)
131.9(CHAr), 130.3(CAr), 128.9(CHAr), 128.7(CHAr), 127.0(CHAr),
126.7(CHAr), 125.6(CHAr), 124.8(CHAr), 124.1(CHAr), 123.1(CHAr),
122.8(CHAr), 122.6(CHAr), 112.5(CHAr), 53.1(CH2), 24.7(CH3acetate).
Anal. Calc. for C44H34N6O8Pd2: C, 53.51; H, 3.47; N, 8.51. Found:
C, 52.56; H, 3.40; N, 7.76%; FT-IR (KBr, cmꢁ1) 1618 (C@N), 1562,
4.3. General procedure for the Mizoroki–Heck coupling reactions
In a typical experiment, an oven-dried 25 mL vial equipped with
a stir bar and septum was charged with 1 mol % catalyst and base
(2.0 mmol). Under nitrogen, DMA (3 mL), aryl halide (1.0 mmol)
and n-butylacrylate (2.0 mmol) were added via syringe. The flask
was then placed in a pre-heated sand bath at 145 °C. After 24 h
the vial was removed from the sand bath and water (20 mL) added
followed by extraction with ether (3 ꢃ 10 mL). The combined
organic layers were washed with saturated aqueous NaCl
(10 mL), dried over anhydrous MgSO4, filtered and the internal
standard (dodecahydrotriphenylene) was added. Solvent was
removed under vacuum. The residue was dissolved in CDCl3 and
analyzed by 1H NMR. Yields were determined by 1H NMR against
dodecahydrotriphenylene as the internal standard [16].
1520. HRMS m/z calcd. for
C44H34N6O8Pd2 987.6162 [M],
929.0379 [MꢁOAc]+; found 929.0390 [MꢁOAc]+.
4.2.2. Bis(-acetato)bis(1-p-nitrophenylimino-2-p-methylphenyliso
indoline)dipalladium(II) (6)
Complex 6 was obtained as a yellow powder in 36% yield (270 mg)
from 2 (254 mg, 0.740 mmol) and Pd(OAc)2 (197 mg, 0.878 mmol).
1H NMR (CDCl3): d 8.10 (d, J = 8.6, 2H, Ar), 7.66 (d, J = 8.8, 2H, Ar),
7.52 (m, 2H, Ar), 7.38 (d, J = 7.5, 2H, Ar), 7.33 (d, J = 7.5, 2H, Ar), 7.11
(m, 4H, Ar), 6.83 (d, J = 7.9, 2H, Ar), 6.16 (d, J = 8.2, 2H), 5.82 (m, 4H,
Ar), 4.61 (d, J = 17.3, 2H, CH2), 3.31 (d, J = 17.3, 2H, CH2), 2.38 (s, 6H,
Ar-CH3), 1.68 (s, 6H, acetate); 13C{1H} NMR (CDCl3): d 180.0 (Cacetate),

J.M. Chitanda et al. / Inorganica Chimica Acta 379 (2011) 122–129
129
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Acknowledgments
We gratefully thank the Natural Sciences and Engineering Re-
search Council of Canada (NSERC) for financial support and the
Canadian Government through the Commonwealth Scholarship
fund for J.M.C.’s doctoral fellowship.
[11] J.M. Chitanda, D.E. Prokopchuk, J.W. Quail, S.R. Foley, Organometallics 27
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(b) T. Tsuritani, S. Kii, A. Akao, K. Sato, N. Nonoyama, T. Mase, N. Yasuda,
Synlett 5 (2006) 801;
CCDC 766977, 766978, 766979 and 766980 contain the supple-
mentary crystallographic data for complexes 5ꢂCHCl3,
6ꢂH2OꢂCH2Cl2, 7 and 8, respectively. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif. Supplementary data
associated with this article can be found, in the online version, at
doi:10.1016/j.ica.2011.09.054.
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