Conversion of novel palladacycles into oxopyrrolo[3,4-b]quinolines

Article abstract of DOI:10.1016/j.poly.2008.10.054

The quinolinylcyclopalladated complexes 3a-b were synthesised in good yields (81% and 77%) by the insertion reaction of the prepared dinuclear palladium complexes [Pd(C,N-2-C₉H₄N-CHO-3-R-6)Cl(PPh₃)]₂ [(R = H (2a

Full text of DOI:10.1016/j.poly.2008.10.054

Polyhedron 28 (2009) 349–359
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Conversion of novel palladacycles into oxopyrrolo[3,4-b]quinolines
*
Abdel-Sattar S. Hamad Elgazwy
Department of Chemistry, Faculty of Science, University of Ain Shams, Abbassia 11566, Cairo, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
The quinolinylcyclopalladated complexes 3a–b were synthesised in good yields (81% and 77%) by the
insertion reaction of the prepared dinuclear palladium complexes [Pd(C,N-2-C9H4N-CHO-3-R-
6)Cl(PPh3)]2 [(R = H (2a), R = OMe (2b)] with isonitrile XyNC (Xy = 2,6-Me2C6H3). The cyclopalladated
complexes 3a–b were also obtained in low yields (39% and 33.5%) via a one pot oxidative addition reac-
tion of quinoline chloride 1a–b with isonitrile XyNC:Pd(dba)2 (4:1). The reactions of 3a–b with Tl(TfO)
(TfO = triflate, CF3SO3) in the presence of H2O or EtOH causes depalladation reactions of the complexes
to provide the corresponding organic compounds 4a–b, 5a–b and 6a–b in yields (41%, 27% and 18–
19%). The products were characterized by satisfactory elemental analyses and spectral studies (IR, 1H,
13C and 31P NMR). The crystal structures of 2a, 3a and 3b were determined by X-ray diffraction studies.
Ó 2008 Elsevier Ltd. All rights reserved.
Received 3 September 2008
Accepted 8 October 2008
Available online 10 December 2008
Keywords:
Quinoline
Arylpalladium complexes
Oxopyrrolo[3,4-b]quinolines
Isocyanides
1. Introduction
mon ‘Pd2C2N2’ central cores formed by oxidative addition of the
chloroquinolines 1a–b to a Pd(0) is supported by X-ray structures.
The chemistry of arylpalladium complexes is a topic of great
interest because such compounds participate in many organic
reactions [1–12]. Cyclopalladated complexes (CPCs) are one of
the most popular classes of organopalladium derivatives, which
are widely applied in organic synthesis, organometallic catalysis
and new molecular materials. Among them, the most investigated
cyclopalladated complexes are five- or six-membered rings fused
with an aromatic ring, and the metallated carbon is usually an aro-
matic sp2 carbon [13–17]. However, six-membered palladacycles
with iminoyl (C@N–) sp2 carbon are rather rare [18]. This is prob-
ably due to poor stability which brings difficulties of preparation,
isolation and characterization of these complexes. The limitation
can be overcome by changing the nature of the metallated carbon
atom, the type of donor groups and their substituents. Some of
these reactions involved ortho-functionalized aryl complexes that
after insertion of isocyanides gave heterocyclic products in which
the ortho group is included [19–21]. Establishing synthetic proce-
dures for these complexes invariably involve the presence of other
strongly coordinated ligands, such as PPh3 [22–24], and these are
attracting our interest. There is relatively little known concerning
the cyclometallation of aldehyde functionalities [25–34]. The
interest of this subject has prompted us to prepare arylpalladium
complexes containing ortho-–CHO functionalized groups. In this
contribution we present the synthesis and characterization of
novel mono- and dimeric palladacycles as well as their utility as
precursors for the synthesis of valuable organic products. The
structure of dimeric [N-aryl-Pd-Cl(PPh3)]2, 2a–b, with non com-
The utility of the cyclopalladated complexes 3a–b in organic syn-
thesis via their depalladation reactions to provide amidic acid or
esters (4a–b, 5a–b and 6a–b) are the most outstanding points of
this manuscript. The sequence of the reactions led eventually to
compounds that could potentially possess pharmacological prop-
erties [35–53].
2. Results and discussion
Oxidative addition reactions of 2-chloro-6-R-3-quinolinecrab-
oxaldehydes R = H (1a), R = OMe (1b) toward a stoichiometric
amount of [Pd(dba)2] = ([Pd2(dba)3] ꢀ dba; dba = dibenzylidene-
acetone) [54] in the presence of a neutral ligand such as PPh3
(1:2:1) under nitrogen in degassed acetone gave the dimeric palla-
dium complexes{Pd[C9H5-CHO(3)]Cl(PPh3)}2 2a, {Pd[-6-OCH3-
C9H4-CHO(3)]Cl(PPh3)}2 2b in moderate yields (43% and 31%),
through the coordination of the quinolinyl nitrogen. Subsequently,
the insertion reaction of 2,6-dimethylphenyl isocyanide XyNC
(Xy = 2,6-Me2C6H3) into the dinuclear complexes in CH2Cl2 at room
temperature eventually formed the monuclear complexes 3a–b in
high yields (81% and 77%). These palladacycles 3a–b could also be
obtained in low yields (39% and 33.5%) by direct oxidative addition
of
2-chloro-6-R-3-quinolinecraboxaldehydes
1a–b
toward
Pd(dba)2 in the presence of a stoichiometric amount of isocyanide
XyNC in degassed acetone at room temperature, as depicted in
Scheme 1.
It was envisaged that the oxidative addition reaction of 1a–b
with Pd(dba)2/PPh3 could give the expected complex in a transoid
form (A). However, isolation of the trans complexes failed, and
only a yellow powder solid was isolated in the pure form that
* Tel.: +20 22617 3044; fax: +20 24831 836.
E-mail addresses: hamad@asunet.shams.edu.eg, aselgazwy@yahoo.com
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.10.054

350
A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
O
O
H
R
R
R
N
Xy
Tl(TfO)
H2O or
EtOH
N
Xy
O
2 Pd(dba)2
XyNC(4 mole)
acetone
N
N
N
Cl
Cl
NHXy
Pd
NHXy
R'O
-TlCl-Pd
1a-b
NXy
XyNC
NXy
a) R = H
b) R = OMe
R'
H
R
3a-b
4a-b
a)
H
Pd[(PPh3)]4
CH2Cl2
b)
OMe H
XyNC
(Exs. 8 mole)
CH2Cl2
Pd(dba)2
PPh3
acetone
6a-b a)
Et
Et
H
OMe
b)
R
Me
Cl
Ph3P
OHC
R' = H
O
Pd
Pd
Xy =
N
N
R
Me
N
Xy
Cl
PPh3
CHO
R
N
O
2a-b
5a-b
a) R = H
b) R = OMe
NHXy
NHXy
Scheme 1.
corresponded to the dimeric palladium complexes 2a–b, as out-
lined in Scheme 2. This is probably due to the result of the inter-
change between the nitrogen donor of the quinoline ring and the
PPh3 ligand of palladium, which is a very well-known process
[55]. One might believe that complexes (A) and (B) are intermedi-
ates for the formation of complexes 2a–b and also suggest that the
presence of PPh3 as a ligand could be responsible for the inter-
change of the ligands and existence of complex 2a or 2b in solution
as a mixture of complexes derived from two trans forms. The for-
mation of the dimeric complexes 2a–b are consistent with the re-
These complexes were confirmed by the appearance of one sin-
glet signal in their 31P NMR spectra. The reaction products were
identified by comparison of the 31P NMR spectra of the reaction
mixture with those of related reported complexes which showed
two AB resonance patterns. The 31P NMR spectra recorded in case
of R = H (2a) and R = OMe (2b) showed resonances at d 20.67 and
21.37 ppm.
The 1H NMR spectra did not show the presence of any impuri-
ties for either of the complexes 2a or 2b, although the quinoline
backbone shows slight variations when complexes 2a or 2b are
compared. However, we feel that not enough was known about
palladium–carbon bonds of these complexes, through four bonds.
This promoted us to place emphasis on these data. While this
lated dimeric palladium complex [Pd(l-pyridine)Cl(PPh3)]2,
formed by the oxidative addition of 2-chloropyridine to the com-
plex Pd(PPh3)4 [56].
R
CHO
PPh3
R
CHO
Cl
2 Pd(dba)2
2 PPh3
acetone
N
Pd
Cl
N
Ph3P
1a-b
A
( )
expected
Pd(PPh3)4
CH2Cl2
- PPh3
Ph3P
OHC
R
R
CHO
PPh3
Cl
Pd
N
N
Pd
N
Pd
Cl
Cl
B
( )
R
CHO
PPh3
2a-b
Scheme 2.

A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
351
Fig. 2. Thermal ellipsoid plot (50% probability level and solvent omitted) of 3a. The
hydrogen atom attached to N(20) has been displayed for clarity. Selected bond
lengths (Å) and angles (°): Pd–C(40) = 1.9425(18), Pd–C(10) = 1.9999(17), Pd–N(1) =
2.0864(14), Pd–Cl(1) = 2.4398(4), N(1)–C(2) = 1.325(2), N(1)–C(8A) = 1.388(2),
N(10)–C(10) = 1.270(2), N(10)–C(11) = 1.420(2), N(20)–C(20) = 1.372(2), N(20)–
C(21) = 1.418(2), N(30)–C(9) = 1.389(2), N(30)–C(30) = 1.429(2), N(30)–C(31) =
1.434(2), N(40)–C(40) = 1.151(2), N(40)–C(41) = 1.409(2), C(2)–C(30) = 1.452(2),
C(3)–C(9) = 1.479(2), C(9)–O = 1.221(2), C(10)–C(20) = 1.505(2), C(20)–C(30) =
1.366(2), C(40)–Pd–C(10) = 91.93(7), C(40)–Pd–N(1) = 178.97(6), C(40)–Pd–
Cl(1) = 84.21(5), C(10)–Pd–N(1) = 87.11(6), C(10)–Pd–Cl(1) = 173.33(5), N(1)–Pd–
Cl(1) = 96.78(4), C(2)–N(1)–C(8A) = 116.44(14), C(2)–N(1)–Pd = 116.23(11), C(8A)–
Fig. 1. Thermal ellipsoid plot (50% probability level and solvent omitted CH2Cl2) of
2a. Selected bond lengths (Å) and angles (°): Pd(1)–C(12) = 1.9919(17), Pd(1)–
N(1) = 2.0944(14), Pd(1)–P(1) = 2.2906(5), Pd(1)–Cl(1) = 2.3816(6), Pd(1)–Pd(2) =
3.0818.(5),
2.2661(7), Pd(2)–Cl(2) = 2.3812(5), N(1)–C(2) = 1.330(2), N(11)–C(12) = 1.324(2),
C(12)–Pd(1)–N(1) = 82.22(6), C(12)–Pd(1)–P(1) = 92.32(5), N(1)–Pd(1)–P(1) =
Pd(2)–C(2) = 2.0081(6),
Pd(2)–N(11) = 2.1115(14),
Pd(2)–P(2) =
174.53(4), C(12)–Pd(1)–Cl(1) = 173.90(5), N(1)–Pd(1)–Cl(1) = 92.30(4), P(1)–
Pd(1)–Cl(1) = 93.14(2), C(12)–Pd(1)–Pd(2) = 66.01(5), N(1)–Pd(1)–Pd(2) = 63.12(4),
P(1)–Pd(1)–Pd(2) = 114.865(14), Cl(1)–Pd(1)–Pd(2) = 113.865(19), C(2)–Pd(2)–
N(11) = 84.88(6), C(2)–Pd(2)–P(2) = 93.24(5), N(11)–Pd(2)–P(2) = 175.12(4), C(2)–
Pd(2)–Cl(2) = 174.14(5), N(11)–Pd(2)–Cl(2) = 90.20(4), P(2)–Pd(2)–Cl(2) = 91.91(2),
C(2)–Pd(2)–Pd(1) = 66.30(5), N(11)–Pd(2)–Pd(1) = 63.27(4), P(2)–Pd(2)–Pd(1) =
111.854(17), Cl(2)–Pd(2)–Pd(1) = 114.188(16).
N(1)–Pd = 126.75(11),
C(10)–N(10)–C(11) = 123.11(15),
C(20)–N(20)–C(21) =
129.41(17), C(9)–N(30)–C(30) = 112.76(14),
C(9)–N(30)–C(31) = 122.82(15),
C(30)–N(30)–C(31) = 124.29(14), C(40)–N(40)–C(41) = 171.2(2), N(1)–C(2)–C(3) =
123.94(15), N(1)–C(2)–C(30) = 127.31(15), C(3)–C(2)–C(30) = 108.75(15), C(2)–
C(3)–C(9) = 108.26(14), O–C(9)–N(30) = 125.39(17), O–C(9)–C(3) = 129.47(16),
N(30)–C(9)–C(3) = 105.12(14), N(10)–C(10)–C(20) = 116.45(15), N(10)–C(10)–
Pd = 127.94(13), C(20)–C(10)–Pd = 115.61(11), C(30)–C(20)–N(20) = 122.27(16),
C(30)–C(20)–C(10) = 118.02(15), N(20)–C(20)–C(10) = 118.83(15), C(20)–C(30)–
N(30) = 127.76(15),
C(20)–C(30)–C(2) = 126.11(16),
N(30)–C(30)–C(2) =
104.88(13), N(40)–C(40)–Pd = 171.71(16).
observation can be rationalized for 2a–b, we were surprised that
the cyclopalladated product showed almost no change in view of
the angular distortion involved in forming the six-membered pal-
ladacycles. The IR (Nujol, cmꢁ1) bands assignable to the
m
(C@O),
A mechanistic proposal depicts the formation of the possible
intermediates [Pd{C(@NXy)3Ar}Cl(CNXy)] [I] which are quickly cy-
clized to give iminoacyl quinolinylpalladium 3a and 3b, and not
the expected complex [II]. We believe that a nucleophilic attack
of the nitrogen of the primarily inserted isocyanide at the formyl
carbon could give the isoindole ring [III–V]. The intermediate
[IV] could evolve to [V], bearing a carbon–carbon double bond,
which could undergo an intermolecular proton migration from
the OH group of the intermediate [V] to the nitrogen of the second
inserted isocyanide. There is no precedent for this type of structure
conformation with migration of the proton to the nitrogen atom of
the second inserted isocyanide, it was supported by X-ray struc-
tures, displaying the nitrogen proton at N(20)–H (3a, Fig. 2) and
N(5)–H (3b, Fig. 3). The favored attack of the quinolinyl nitrogen
at the (Pd) metal center in intermediate [VI] could turn into imi-
noacyl quinolinylpalladium 3a or 3b. The reported [57–62] synthe-
sis of a highly functionalized ketenimine from di-insertion of XyNC
into an (o-formylaryl) palladium complex is consistent with the re-
sult described here. The formation of such a ketenimine is also the
result of the attack of the nitrogen of the primarily inserted isocy-
anide at the formyl carbon. A mechanistic proposal consistent with
literature data [63], is given in Scheme 3.
m
(C@N) and m(C@C) modes in 2a–b indicating the non-coordination
of the carbonyl group in these complexes. In complex 2a, the IR
spectrum shows bands at 1688, 1612 and 1582 cmꢁ1 and for 2b
these bands appear at slightly lower values at 1678, 1584 and
1546 cmꢁ1 respectively. The complexes 2a–b show in their IR spec-
tra a strong band at ca. 1688 and 1678 cmꢁ1 assignable to
m(C@O)
of the formyl group. These frequencies are similar to that observed
in the starting materials 1a–b, indicating that there is no coordina-
tion of the formyl group to the metal atom.
2.1. Insertion of 2,6-dimethylphenyl isocyanide XyNC (Xy = 2,6-
Me2C6H3)
Oxidative addition of 2-chloro-6-R-3-quinolinecarboxaldehy-
des 1a–b [R = H (1a), R = OMe (1b)] (1.5) to a mixture of Pd(dba)2
and XyNC (Xy = 2,6-Me2C6H3) in 1:4 ratios in acetone at room tem-
perature yields the tri-inserted iminoacyl palladium complexes
3a–b in low yields (39%, 33.5%). Instead of the required 4:1.5:1 mo-
lar ratios of reagents XyNC:1a–b:Pd(dba)2 for the formation of 3a–
b, the stoichiometric amounts of this mixtures used were 3:1.5:1,
2:1.5:1, 2:1:1, 1:1.5:1, 1:1:1 (3a) and 3:1.5:1, 2:1.5:1, 2:1:1,
1:1.5:1, 1:1:1 (3b), unfortunately, it was not possible to isolate
the inserted products in this regard.
The reactivity of the dinuclear palladium complexes 2a–b were
examined toward the bulky isocyanide XyNC (Xy = 2,6-Me2C6H3),

352
A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
The products were analyzed by IR, 1H NMR spectroscopy and
single-crystal X-ray diffraction studies. IR (Nujol, cmꢁ1) bands
were assignable to mNH mC@J and C@N, for the iminoacyl quin-
,
mC„N
,
m
olinylpalladium complexes 3a and 3b with no significances differ-
ences, indicating the cyclization of the carbonyl group within those
complexes. In the case of 3a the bands appear at
3338, (C„N) 2361, (C@O) 1716 and
(C@N) 1558 cmꢁ1, and in
the case of 3b the bands appear at (NH, broad band) 3360,
(C„N) 2182, (C@O) 1704 and
(C@N) 1602 cmꢁ1. This suggests
m(NH, broad band)
m
m
m
m
m
m
m
little change in the carbonyl stretching frequency of 3a or 3b due to
complexation, and the electron releasing methoxyl group could
confer special properties to the formyl group, for example, facilitat-
ing its coordination to the primarily inserted isocyanide (C@NXy)
intermediate and nucleophilic attack of the nitrogen on the formyl
carbon could give cyclometallated species of the important isoind-
olinone. The complexes 3a and 3b show a strong band in their IR
spectra at 1716 and 1704 cmꢁ1 assignable to
m(C@O). This fre-
quency is not similar to that observed in the starting materials
1a–b or 2a–b and indicates the coordination of the carbonyl group
to the isoindolinone ring. The 1H NMR spectrum of complex 3a in
CDCl3 was recorded and found to contain seven singlet resonances
at different chemical shifts, each corresponding to methyl groups,
appearing at d 2.55 (s, Me, 3H), 2.49 (s, Me, 3H), 2.30 (s, Me, 3H),
2.19 (s, Me, 6H), 2.11 (s, Me, 3H), 1.58 (s, Me, 3H) and 0.62 (s,
Me, 3H) ppm. There is one singlet signals integrated for 2 equiv.
methyl groups of the coordinated isocyanide (CNXy) which ap-
pears at d 2.19. The 1H NMR spectrum of complex 3b in CDCl3
was recorded and found to contain six singlet resonances at differ-
ent chemical shifts, each corresponding to methyl groups, appear-
ing at d 2.54 (s, Me, 3H), 2.49 (s, Me, 3H), 2.29 (s, Me, 3H), 2.18 (s,
Me, 6H), 2.12 (s, Me, 6H) and 0.62 (s, Me, 3H) ppm. There are two
singlet signals for the four methyl groups appearing at d 2.18 (s,
6H, 2Me(Xy)) and 2.12 (s, 6H, 2Me(Xy)), one of which is for the in-
serted XyNC, indicating a cis geometry and no free rotation of the
Xy groups. The other of the two singlet signals integrated to
2 equiv. methyl groups is from the coordinated isocyanide. This
suggests steric hindrance that prevents the rotation of three xylyl
groups, while the fourth one rotates freely.
Fig. 3. Thermal ellipsoid plot (50% probability level and solvent omitted) of 3b. The
hydrogen atom attached to N(5) has been displayed for clarity. Selected bond
lengths (Å) and angles (°): Pd(1)–C(30) = 1.944(2), Pd(1)–C(40) = 2.002(2), Pd(1)–
N(1) = 2.0905(18), Pd(1)–Cl(1) = 2.4283(5), N(1)–C(1) = 1.332(3), N(1)–C(9) =
1.382(3), N(2)–C(10) = 1.383(3), N(2)–C(12) = 1.432(3), N(2)–C(61) = 1.438(3),
N(3)–C(30) = 1.153(3),
C(41) = 1.429(3), N(5)–C(50) = 1.363(3), C(30)–Pd(1)–C(40) = 91.67(8), C(30)–
Pd(1)–N(1) = 178.75(8), C(40)–Pd(1)–N(1) = 87.14(8), C(30)–Pd(1)–Cl(1) =
N(3)–C(31) = 1.404(3),
N(4)–C(40) = 1.266(3),
N(4)–
84.53(6), C(40)–Pd(1)–Cl(1) = 175.94(6), N(1)–Pd(1)–Cl(1) = 96.64(5), C(1)–N(1)–
C(9) = 116.68(18), C(1)–N(1)–Pd(1) = 116.25(14), C(9)–N(1)–Pd(1) = 126.45(14),
C(10)–N(2)–C(12) = 112.44(18),
C(10)–N(2)–C(61) = 119.09(18),
C(12)–N(2)–
C(61) = 127.39(18), C(30)–N(3)–C(31) = 170.0(2), C(40)–N(4)–C(41) = 120.57(18),
C(50)–N(5)–C(51) = 129.11(19), C(6)–O(1)–C(14) = 116.23(18), N(1)–C(1)–C(2) =
122.76(19), N(1)–C(1)–C(12) = 128.49(19).
2.2. Depalladation via reactions with Tl(TfO)
and it depends on nature of the ligands and on the reaction condi-
tions. Thus when the insertion reaction takes place at different mo-
lar ratios of XyNC to complex, the inserted products obtained are
the result of tri-insertion processes. The mono-insertion and di-
insertion of XyNC at 1:1 or 1:2 molar ratios are not being isolated.
The reaction of the dinuclear palladium complexes 2a–b with
8 equiv. of XyNC at room temperature with a longer reaction time
(16 h) provided the inserted products of iminoacyl quinolinylpalla-
dium complexes 3a–b. Instead of the required (8:1) equivalents of
XyNC:2a–b, the stoichiometric amounts of 3:1, 4:1, 5:1, 6:1 and
7:1 were used, and it was not possible to isolate complexes 3a–b
in case of 3:1, 4:1 and 5:1 molar ratios.
The inserted products were formed from the insertion of 2,6-
dimethylphenyl isocyanide (XyNC) into the C–Pd bond and the dis-
placement of PPh3 by the XyNC ligand. These kinds of complexes
are very poorly represented in the iterature, the only example
being those recently prepared by Vicente et al. [63] and suggested
that the presence of PPh3 during the insertion of XyNC into the
dinuclear palladium complexes 2a–b could be responsible for the
change of reactivity of the intermediate complexes. It is possible
that free PPh3 coordinates in the intermediate complexes, forcing
the insertion of the two isocyanide ligands. A mechanistic scheme
depicting the formation of the various products, including possible
intermediates, consistent with literature data [63] is given in
Scheme 4.
The reaction of complexes 3a–b with Tl(TfO) was carried out in
CH2Cl2 to give after 20 h at room temperature a precipitate of TlCl
plus metallic palladium and a solution from which the highly func-
tionalized 4a–b and 5a–b could be isolated (70% total yield,
Scheme 5). These tautomers could not be separated by chromatog-
raphy, but they displayed an exploitable difference in solubility.
Thus, when a solution of both products in Et2O was evaporated
to dryness and Et2O added again, the major tautomer did not redis-
solve and could be isolated by filtration, while the other tautomer
could be similarly separated from the mother liquor. In the solid
state 5a–b and 4a–b are stable and they do not interconvert. How-
ever, if 4a–b are dissolved in CH2Cl2 and refluxed for 16 h, they
transform completely into 5a–b. The latter are stable at room tem-
perature in CDCl3 for several days, while under the same condi-
tions 4a–b transform partially into 5a–b. The addition of an acid
does not accelerate the interconversion of these products. Several
reviews dealing with imidoyl compounds have discussed the ques-
tion of whether imidic acids can exist in general [64]. They are
unstable compounds that may be in equilibrium with the stable
amide (5a–d) molecules. This is confirmed by theoretical investiga-
tions, which demonstrate that the amide form is about 11 kcal/mol
more stable than the tautomeric imidic acid (4a–d) [65]. When the
reaction of 3a–b with Tl(TfO) was carried out in CH2Cl2 plus a drop
of EtOH, 6a–b were obtained and the yields varied from 18% to
40%, depending on the amount of added of EtOH.

A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
353
R
CHO
Xy
N
N
Cl
Pd
XyN
-PPh3
CNXy
XyN
A
Ring Closure
)
II
[ ]
B
)
Ring Closure
O
H
O
O
H
R
R
R
H
A
Xy
Pd
N
Xy
Xy
N
N
CNXy
Cl
A
Ring closure
N
CNXy
Cl
N
N
B
Cl
Pd
XyNC
Pd
XyN
NXy
XyN
NXy
NXy
NXy
I
[ ]
IV
[ ]
III
[
]
= PPh3
O
H
O
R
O
R
N Xy
R
N Xy
-PPh3
N
N
Xy
Cl
Pd
N
XyNC
NH
Xy
N
Cl
Pd
Cl
XyNC
Pd
NH
Xy
N
N
XyNC
Xy
[VI]
NXy
Xy
NXy
3a, 3b
V
[ ]
a) R = H
b) R = OMe
Scheme 3.
R
XyNC
XyN
NXy
XyN
Cl
Ph3P
OHC
OHC
2
Pd Cl
CNXy
8 XyNC
CH2Cl2
Pd
N
Pd CNXy
PPh3
OHC
N
N
Cl
Pd
CHO
PPh3
N
Cl
1. excess
XyNC
2a-b
R
R
proton migration
NXy
R
O
2. Ring
closure
-PPh3
Xy
N
H
O
XyN
NXy
NXy
CNXy
Xy
H
NXy
Pd
N
NHXy
NXy
O
N
Pd
CNXy
N
Cl
N
Pd
Cl
CNXy
Cl
R
R
R
3a-b
Scheme 4.

354
A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
O
O
O
O
R
R
R
R
N
Xy
N
Xy
N
Xy
N
Xy
N
N
Tl(TfO)
H2O,
-TlCl-Pd
N
Tl(TfO)
EtOH,
-TlCl-Pd
N
NHXy
HO
NHXy
O
NHXy
NHXy
EtO
Cl
Pd
NXy
4a-b
NHXy
5a-b
NXy
NXy
XyNC
6a-b
3a, 3b
Scheme 5.
Ar
NXy
Ar
NXy R' = H
Ar
NHXy
R' = H, Et
Tl(TfO)
-TlCl
Ar
NXy
{PdL2(S)} TfO
OR'
4a-b
O
PdClL2
S = H2O,
or
[A]
5a-b
6a-b
3a, 3b
EtOH
ROH
{PdHL2(S)OTf
O
Pd + 2L + HOTf
R
N
Xy
Ar =
N
NHXy
Scheme 6.
Therefore, the depalladation of these inserted complexes repre-
3a ꢀ CH2Cl2 (Fig. 2) and reddish crystals of 3b ꢀ CH2Cl2 ꢀ C2H6O
(Fig. 3) were determined by X-ray analysis. The Pd–C bond dis-
tances of the iminoacyl ligands decrease, in agreement with the
decreasing electron delocalization influence of the extended of
electron donating group (OMe) located in position (6), as shown
in complexes 3a–b compared with 2a, or may be decreased due
to the trans influence of the ligands, thus these values are (in Å):
Pd(1)–C(12) 2.0081(16), Pd(2)–C(2) 1.9919(17) (2a); Pd–
C(40) = 1.9425(18), Pd–C(10) = 1.9999(17) (3a); Pd–C(30) =
1.944(2), Pd–C(40) = 2.002(2) (3b).
The Pd–Cl distances in (Å) are: Pd(1)–Cl(1) 2.3816(6), Pd(2)–
Cl(2) 2.3812(5) 2a; Pd–Cl 2.4398(4) 3a, Pd–Cl 2.4283(5) 3b. Simi-
larly, the Pd–N bond distance in complexes 2a, 3a and 3b were
compared: Pd(1)–N(1) 2.0944(14), Pd(2)–N(2) 2.1115(14) 2a; Pd–
N(1) 2.0864(14) 3a and 2.0905(18) 3b. Those show the greater
trans influence of the carbon-donor iminoacyl ligand with respect
to the chloro ligand. Looking at these scales, our proposal that
the transphobia could be directly related to the trans influence is
reinforced [66] under this assumption; the two ligands with a great
trans influence will suffer a great transphobia [67].
The structure of 2a (Fig. 1) clearly shows the formation of a pal-
ladium atom in a square-planar environment due to the coordina-
tion environment consisting of trans phosphine, chloro ligands and
nitrogen, carbon quinolinyl ligands. The mean deviation of atoms
Pd(1), P(1), N(1), Cl(1), C(1) and Pd(2), P(2), N(2), Cl(2), C(2) from
the best plane is [Pd(2)–C(2)–Pd(1)–C(12) = 0.0162 Å], [Pd(2)–
P(2)–Pd(1)–P(1) = 0.7912 Å], [Pd(2)–Cl(2)–Pd(1)–Cl(1) = 0.004 Å]
and [Pd(2)–N(11)–Pd(1)–N(1) = 0.0171 Å]. As expected, for the
Pd–C bond distances, Pd(2)–C(2) (2.0081(16) Å) is significantly
longer than Pd(1)–C(12) (1.9919(17) Å), the difference being
0.0162 Å. The Pd–N bond distance Pd(2)–N(11) (2.1115(14) Å) is
significantly longer than that for Pd(1)–N(1) (2.0944(14) Å), and
the difference here is 0.0171 Å, as a result of coordination of the
nitrogen atom to Pd(II). However, the Pd–Cl bond distance Pd(2)–
Cl(2) (2.3812(5) Å) is just a little bit longer than Pd(1)–Cl(1)
(2.3816(6) Å), the difference being 0.004 Å. The Pd–P distance
sents a stoichiometric synthesis of functionalized arene, N-hetero-
cyclic compounds from chloroarenes. As mentioned above, we
fruitlessly attempted the synthesis of some of these organic com-
pounds under catalytic conditions. However, catalytic applications
of these stoichiometric reactions could still be an objective for fu-
ture studies. We believe that all depalladation reactions reported
here share three common steps, as outlined in Scheme 6
(i) The substitution of the chloro ligand in the iminoacyl quin-
olinylpalladium complexes 3a–b by TfO to give the interme-
diates [A], which are formulated as cationic species,
assuming that the very labile TfO is substituted by H2O or
EtOH.
(ii) The nucleophilic attack of the iminoacyl carbon (C@NXy)-Pd
of intermediate [A] by EtOH alcoholysis or H2O hydrolysis,
the latter coming from atmospheric or solvent moisture.
(iii) The decomposition of the resulting adduct (probably
through an intermediate) gives the hydrido palladium com-
plex, metallic palladium, neutral ligand L, HOTf and Ar
C(@NXy)OR0.
Although the very simple reaction pathways proposed in
Scheme 6 allow systematization of the formation of such products,
some questions remain unanswered because too many factors can
influence the results. Finally, we do not attempt to explain the for-
mation of the enol or ketone form and which of these is more sta-
ble, as we cannot account for the influence of the impurities
present in the starting material. A mechanistic scheme depicting
the formation of various products, including possible intermedi-
ates, is outlined in Scheme 6.
2.3. X-ray crystal structures
To further confirm the structures of the products, the molecular
structures of yellow crystals of 2a (Fig. 1), red crystals of

A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
355
Pd(2)–P(2) (3.0818(5) Å) is significantly longer than Pd(1)–P(1)
(2.2906 Å) and the difference is 0.7912 Å. The reason for the devi-
ation of the Pd(2) compared to Pd(1) in the bond distances for all
the ligands around it is due to the greater steric hindrance of
PPh3 and also the trigonal pyramids for the phosphine atom. The
angles around Pd(1) and Pd(2) have been compared: C(2)–Pd(2)–
N(11) (84.88(6)°) is significantly larger than C(12)–Pd(1)–N(1)
(82.22 (6)°) and the difference is 2.66°; C(2)–Pd(2)–P(2)
(93.24(5)°) is slightly larger than C(12)–Pd(1)–P(1) (92.32(5)°)
and the difference is 0.92°; N(11)–Pd(2)–P(2) (175.12(4)°) is
slightly larger than N(1)–Pd(1)–P(1) (174.53(4)°) and the differ-
ence is 0.59°; C(2)–Pd(2)–Cl(2) (174.14(5)°) is slightly larger than
C(12)–Pd(1)–Cl(1) (173.90(5)°) and the difference is 0.24°;
N(11)–Pd(2)–Cl(2) (90.20(4)°) is smaller than N(1)–Pd(1)–Cl(1)
(92.30(4)°) by 2.10°; P(2)–Pd(2)–Cl(2) (91.91(2)°) is smaller than
[Pd]C@NXy bond distance of the iminoacyl ligand in complex 3b
is N(4)–C(40) 1.266(3) Å; N(5)–C(50) 1.363(3) Å and N(2)–C(12)
1.432(3) Å are the C@N distances corresponding to the inserted
molecule of XyN@C and N(3)–C(30) 1.153(3) Å is the C@N distance
corresponding to the inserted molecule of CNXy. All these lengths
are as expected for a C@N bond [mean values for the C(aryl)–C@NR
distances lie in the range 1.432–1.382 Å] [68–70]. The aryl
C@N(Xy)[Pd] distance corresponding to the third inserted mole-
cule of XyNC in 3b is significantly longer than the other related dis-
tance, N(4)–C(40) 1.266(3) Å, as a result of coordination of the
nitrogen atom to Pd(II). This fact, the angles around Pd (C(30)–
Pd(1)–C(40) 91.67(8)°, C(30)–Pd(1)–N(1) 178.75(8)°, C(40)–
Pd(1)–N(1) 87.14(8)°, C(30)–Pd(1)–Cl(1) 84.53(6)°, C(40)–Pd(1)–
Cl(1) 175.94(6)°, N(1)–Pd(1)–Cl(1) 96.64(5)°) and the short
C(12)–C(50) bond 1.365(3) Å compared to C(40)–C(50)
P(1)–Pd(1)–Cl(1)
(93.14(2)°) by
1.23°;
C(2)–Pd(2)–Pd(1)
1.507(3) Å, suggest a delocalization of
p electron density around
(66.30(5)°) is slightly larger than C(12)–Pd(1)–Pd(2) (66.01(5)°)
and the difference is 0.29°; N(11)–Pd(2)–Pd(1) (63.27(4)°) is very
slightly larger than N(1)–Pd(1)–Pd(2) (63.12(4)°) and the
difference is 0.15°; P(2)–Pd(2)–Pd(1) (111.854(17)°) is smaller
than P(1)–Pd(1)–Pd(2) (114.865(14)°) by 3.015°; Cl(2)–Pd(2)–
Pd(1) (114.188(16)°) is slightly larger than Cl(1)–Pd(1)–Pd(2)
(113.865(19)°) and the difference is 0.323°. These results suggest
the C(50)–C(12)–N(2) (angle 127.34(19)°) as compared to N(2)–
C(12)–C(1) (angle 105.08(18)°), N(5)–C(50)–C(12) (angle
123.2(12)°) and N(5)–C(50)–C(40) (angle 119.57(19)°). The coordi-
nation environment of the Pd(II) centre is almost square planar.
3. Experimental
a delocalization of
p electron density around N(1) and P(1) as com-
Reactions were carried out without precautions to exclude light,
atmospheric, oxygen and moisture, unless otherwise stated. Melt-
ing points were determined on a Reicher apparatus and are uncor-
rected. Elemental analyses were carried out with a Carlo Erba 1106
microanalyzer. IR spectra were recorded on a Perkin–Elmer 16F P
CFT-IR spectrometer with Nujol mulls between polyethylene
sheets or KBr pellets. NMR spectra were recorded in a Bruker AC
200, Avance 300 or a Varian Unity 300 spectrometer at room tem-
perature unless otherwise stated. Chemical shifts were referenced
pared to N(2) and P(2) and distortion of the bond angles around the
Pd(1) and Pd(2) due to the greater steric hindrance of PPh3.
Fig. 2 clearly shows the structure of the red crystalline quino-
linepalladium complex 3a, with the Pd–C distances Pd–C(40)
1.9425(18) Å and Pd–C(10) 1.9999(17) Å. The Pd–Cl(1) distance is
2.4398(4) Å and the Pd–N(1) bond distance is 2.0864(14) Å; these
show the greater trans influence of the C-donor iminoacyl ligand
is with respect to the chloro ligand. The transphobia [T] is directly
related to the trans influence of the two ligands and the complex
suffers a great transphobia effect. The [Pd]C@NXy bond distance
of the iminoacyl ligand in complex 3a is N(10)–C(10) 1.270(2) Å;
N(20)–C(20) 1.372(2) Å and N(30)–C(30) 1.429(2) Å are the C@N
distances corresponding to the inserted molecule of XyN@C and
N(40)–C(40) 1.151(2) Å is the C@N distance corresponding to the
inserted molecule of CNXy. All these lengths are as expected for
a C@N bond [mean values for the C(aryl)–C@NR distances lie in
the range 1.432–1.382 Å] [68–70]. The aryl C@N(Xy)[Pd] distance
corresponding to the third inserted molecule of XyNC in 3a is sig-
nificantly longer than the other related distances, N(10)–C(10)
1.270(2) Å and N(1)–C(2) 1.325(2) Å, as a result of coordination
of the nitrogen atom to Pd(II). This fact, the angles around Pd
(C(40)–Pd–C(10) 91.93(7)°, C(40)–Pd–N(1) 178.97(6)°, C(10)–Pd–
N(1) 87.11(6)°, C(40)–Pd–Cl(1) 84.21(5)°, C(10)–Pd–Cl(1)
173.33(5)°, N(1)–Pd–Cl(1) 96.78(4)°) and the short C(20)–C(30)
bond 1.366(2) Å compared with C(10)–C(20) 1.505(2) Å, suggest
to TMS (1H and 13C) and H3PO4 31P). The NMR probe temperature
(
was calibrated using ethylene glycol 1H NMR standard methods.
Chromatographic separations were carried out by TLC on silica
gel (70–230 mesh). Some of the preparations required the use of
highly hazardous Tl(I) salts and they should be handle with
caution.
3.1. General method for the synthesis of aryl palladium complexes
(2a–b)
A mixture of [Pd(dba)2] (432 mg, 0.75 mmol), PPh3 (393.45 mg,
1.5 mmol) and 2-chloro-6-R-3-quinolinecarboxaldehyde 1a–b
(0.75 mmol) was mixed under N2 in dry acetone (25 ml). The reac-
tion mixture was stirred for 3–5 h at room temperature, then was
concentrated (ca. 2 ml) and CH2Cl2 (25 ml) was added. The solution
was passed through a pad of silica gel/MgSO4 (3:1) in a fritted fun-
nel, and then evaporated under reduced pressure, and Et2O (15 ml)
was added. The resulting solution was concentrated (ca. 2 ml); a
mixture of the complex and dba was precipitated with n-hexane.
The suspension was stirred for 10 min at RT, filtered off, washed
with Et2O (5 ml), and air-dried to give the yellow solid of 2a–b.
a delocalization of
p electron density around C(20)–C(30)–N(30)
(angle (127.76(15)°) as compared to N(30)–C(30)–C(2) (angle
104.88(13)°), N(20)–C(20)–C(30) (angle 122.27(16)°) and N(20)–
C(20)–C(10) (angle 118.83(15)°). The coordination environment
of the Pd(II) centre is almost square planar.
Red crystals of 3b, also suitable for X-ray analysis, were ob-
tained in a similar manner to its analogue 3a, and the structure
of 3b (Fig. 3) is identical to 3a except for the different substituents
of the OMe group. The Pd–C distances of the iminoacyl quinolinyl-
palladium complex 3b are Pd(1)–C(30) 1.944(2) Å and Pd(1)–C(40)
2.002(2) Å. The Pd–Cl distance (Pd(1)–Cl(1) 2.4283(5) Å) and the
Pd–N bond distance, Pd(1)–N(1), is 2.0905(18) Å; these again show
the greater trans influence of the C-donor iminoacyl ligand is with
respect to the chloro ligand. Looking at these scales, our proposal
that the transphobia [T] could be directly related to the trans influ-
ence is reinforced under this assumption; the two ligands with a
great trans influence will suffer a great transphobia [T] [67]. The
3.1.1. {Pd[C9H5-CHO-(3)]Cl(PPh3)}2 (2a)
Purification via flash column chromatography silica gel (1:1
CH2Cl2/acetone) afforded a yellow solid 2a, Yield: 398 mg, 43%.
M.p.: 177–179 °C dec. A diffraction-quality crystal was grown by
slow diffusion of Et2O into a CH2Cl2 solution. IR (Nujol, cmꢁ1);
m
(HC@O) 1688.4, m(C@N and C@C) 1612.0, 1582.0, 1572.0 and
1538.0. 1H NMR (400 MHz, CDCl3); d 10.39 (s, 2H, CHO), 7.34–
7.90 (m, 17H, Ar–H), 7.25–6.91 [(m, 23H, Ar–H and (PPh3)2], 5.28
[(s, 1H, 1/2 (CH2Cl2)] ppm. 31P {1H} NMR (121 MHz, CDCl3);
20.67 ppm. Anal. Calc. for C56H42N2O2Cl2Pd2P2 (1120.62): C,
60.02; H, 3.78; N, 2.50. Found; C, 60.01; H, 3.75; N, 2.35%.

356
A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
3.1.2. [Pd[-6-OCH3-C9H4-CHO-(3)]Cl(PPh3)}2 (2b)
was evaporated and the residue was triturated with Et2O (15 ml).
The precipitate was filtered, washed with Et2O (2 ꢂ 5 ml), and
air-dried, giving the red solid compound 3b.Yield: 223 mg, 33.5%.
Diffraction-quality crystals were grown by slow diffusion of Et2O
into a CH2Cl2 solution of 3b. M.p.: 238–240 °C. IR (Nujol, cmꢁ1):
Purification via flash column chromatography silica gel (1:1
CH2Cl2/acetone) afforded a yellow-solid 2b, Yield: 277 mg, 31.2%.
M.p.: 180–182 °C dec. A diffraction-quality crystal was grown by
slow diffusion of Et2O into a CH2Cl2 solution of 2b. IR (Nujol,
cmꢁ1);
m(HC@O) 1678.0,
m
(C@N and C@C) 1584.0, 1546.0. 1H
m
(NH, broad band) 3360,
m(C„N) 2182.7, m(C@O) 1704.5, m(C@N)
NMR (400 MHz, CDCl3); d 10.43 (s, 2H, CHO), 7.79–7.46 (m, 15H,
Ar–H), 7.41–7.05 [(m, 22H, Ar–H and (PPh3)2], 6.60 (d, 1H,
J = 2.6Hz), 3.84 (s, 6H, OMe) ppm. 31P {1H} NMR (121 MHz, CDCl3);
21.37 ppm. Anal. Calc. for C58H46N2O4Cl2Pd2P2 (1180): C, 59.00; H,
3.93; N, 2.37. Found; C, 59.08; H, 4.04; N, 2.32%.
1602.4, 1570.1. 1H NMR (200 MHz, CDCl3) d 8.75 (s, 1H, NH),
3
4
8.71 (d, 1H, JHH = 8.6 Hz), 7.67–7.57 (dd, 1H, JHH = 2.6,
3JHH = 9.6 Hz, quinoline-H8), 7.27–7.18 (m, 5H), 7.14–7.11 (s, 1H),
7.07–6.96 (m, 3H), 6.89–6.80 (m, 4H), 6.40–6.36 (d, 1H,
3JHH = 7.6 Hz, quinoline-H), 3.96 (s, 3H, OMe), 2.54 (s, Me, 3H),
2.49 (s, Me, 3H), 2.29 (s, Me, 3H), 2.18 (s, Me, 6H), 2.12 (s, Me,
6H), 0.62 (s, Me, 3H) ppm. Anal. Calc. for C47H44N5O2ClPd
(852) + H2O = (870.79): C, 64.83: H, 5.32: N, 8.04. Found: C,
64.91: H, 5.12: N, 8.04%.
3.2. 4-(2,6-Dimethyl-phenyl)-3-(2,6-dimethyl-phenylamino)-2-(2,6-
dimethyl-phenylimino)-1-[(2,6-dimethyl-phenylisonitrile)]-2,4-
dihydro-1H-4,10b-diaza-acephenanthrylene-5-one-1-
palladium(II)chloride complex (3a)
3.3.2. Method (B)
3.2.1. Method (A)
To a suspension of {Pd[6-OCH3-C9H5-CHO (3)]Cl(PPh3)}2 (2b)
(283 mg, 0.24 mmol) in CH2Cl2 (15 ml), XyNC (248 mg, 1.92 mmol)
was added. The suspension was stirred for 24 h at room tempera-
ture and the color changed from pale yellow into pale red and then
dark red whilst the reaction mixture was monitored. The solvents
were filtered over a pad of anhydrous MgSO4/silica gel (1:3) in a
fritted funnel. The resulting red solution was evaporated and the
residue was triturated with Et2O (15 ml). The precipitate was fil-
tered, washed with Et2O (2 ꢂ 5 ml), and air-dried, giving the red
compound 3b. Yield, 158 mg, 77%. Diffraction-quality crystals were
grown by slow diffusion of Et2O into a CH2Cl2 solution of 3b.
To a suspension of ‘Pd(dba)2’ (300 mg, 0.52 mmol) and XyNC
(274 mg, 2.09 mmol) in acetone (15 ml), 2-chloro-3-quinoline car-
boxaldehyde 1a (149.4 mg, 0.78 mmol) was added under nitrogen.
The suspension was stirred for 5 h at room temperature, then the
solvent was evaporated. The resulting residue was extracted with
CH2Cl2 (25 ml) and the extract filtrate was filtered over anhydrous
MgSO4/silica gel (1:3) in a fritted funnel. The resulting red solution
was evaporated and the residue was triturated with Et2O (15 ml).
The precipitate was filtered, washed with Et2O (2 ꢂ 5 ml), and
air-dried, giving the red compound 3a, yield, 254 mg, 39%. Diffrac-
tion-quality crystals were grown by slow diffusion of Et2O into a
CH2Cl2 solution of 3a. M.p.: Dec. pt: 255 °C. IR (Nujol, cmꢁ1):):
4. Depalladation procedure
m
m
(NH, broad band) 3353,
m(C@O) 1716, 1699, m(C„N) 2361, 2338,
(C@N) 1558, 1541. 1H NMR (200 MHz, CDCl3) d 8.87 (s, 1H, NH),
4.1. General procedure for the acetamidic acids (4a–b) and acetamide
(5a–b)
8.83–8.78 (d, 1H, J = 8.6 Hz), 7.99–7.87 (q, 2H, J = 8.6 Hz), 7.63–
7.55 (t, 1H, J = 7.6 Hz), 7.35–7.22 (m, 3H), 7.19–6.97 (m, 5H),
6.91–6.73 (m, 4H), 6.40–6.37 (d, 1H, J = 7.2 Hz), 2.55 (s, Me, 3H),
2.49 (s, Me, 3H), 2.30 (s, Me, 3H), 2.19 (s, Me, 6H), 2.11 (s, Me,
3H), 1.58 (s, Me, 3H) 0.62 (s, Me, 3H) ppm. Anal. Calc. for
C46H42N5OClPd (822): C, 67.15; H, 5.15; N, 8.50. Found: C, 67.04;
H, 5.09; N, 8.14%.
Tl(TfO) (314 mg, 0.89 mmol) was added to a suspension of 3a–b
(0.89 mmol) in Me2CO (20 ml). The resulting red suspension was
stirred for 20 h. During this time decomposition to metallic palla-
dium was observed and a dark brownish suspension formed. This
was filtered over Celite, and the filtrate was concentrated and ap-
plied to a preparative TLC plate (eluant: n-hexane/Et2O, 1:2). A yel-
low band at Rf = 0.25 was collected and extracted with Me2CO
(30 ml). The resulting solution was dried with anhydrous MgSO4
for 1 h and filtered, and the filtrate was evaporated to dryness, giv-
ing a 2:3 mixture of both tautomers 5a–b and 4a–b. A sample of
this mixture (200 mg) was dissolved in Et2O (30 ml), the solution
was evaporated to dryness, and the residue was treated with
Et2O (30 ml), causing the precipitation of a solid, which was fil-
tered and air-dried to give yellow 4a–b (41%). The same process
was repeated with the mother liquor, giving 5a–b (27%).
3.2.2. Method (B)
To a suspension of {Pd[C9H5-CHO (3)]Cl(PPh3)}2 2a (268 mg,
0.24 mmol) in CH2Cl2 (15 ml), XyNC (248 mg, 1.92 mmol) was
added. The suspension was stirred for 24 h at room temperature.
The color changed from pale yellow into pale red and then dark
red whilst the reaction mixture was monitored. The solvents were
filtered over a pad of anhydrous MgSO4/silica gel (1:3) in a fritted
funnel. The resulting red solution was evaporated and the residue
was triturated with Et2O (15 ml). The precipitate was filtered,
washed with Et2O (2 ꢂ 5 ml), and air-dried, giving the red com-
pound 3a. Yield: 160 mg, 81%. Diffraction-quality crystals were
grown by slow diffusion of Et2O into a CH2Cl2 solution of 3a.
4.2. N-(2,6-Dimethylphenyl)-2-(2,6-dimethylphenylamino)-2-[2-(2,6-
dimethylphenyl)-1-oxo-1,2-dihydro-pyrrolo[3,4-b]quinolin-3-
ylidene]-acetimidic acid (4a)
3.3. 4-(2,6-Dimethyl-phenyl)-3-(2,6-dimethyl-phenylamino)-2-(2,6-
dimethyl-phenylimino)-1-[(2,6-dimethyl-phenylisonitrile)]-8-
methoxy-2,4-dihydro-1H-4,10b-diaza-acephenanthrylene-5-one-1-
palladium(II) chloride complex (3b)
M.p.: 206–208 °C. IR (cmꢁ1):
(C@O),
(C@N) 1682, 1668. 1H NMR (200 MHz, CDCl3) d 8.77 (d,
1H, quinol-H4), 8.37 (dd, 1H, JHH = 1.6, JHH = 8.6 Hz, quinol-H8),
m(OH), m(NH) 3420, 3232 b,
m
m
4
3
3
3
7.97 (d, 1H, JHH = 8.6 Hz, quinol-H5), 7.73 (dd, 1H, JHH = 8.6 and
3.3.1. Method (A)
3
6.9 Hz, quinol-H7), 7.43 (dd, 1H, JHH = 8.6 and 6.8 Hz, quinol-H6),
2-Chloro-6-methoxy-3-quinoline carboxaldehyde 1b (172.86
mg, 0.78 mmol) was added to a suspension of ‘Pd(dba)2’ (300 mg,
0.52 mmol) and XyNC (274 mg, 2.09 mmol) in acetone (15 ml) un-
der nitrogen. The suspension was stirred for 5 h at room tempera-
ture. The solvents were evaporated, the residue was extracted with
CH2Cl2, and the extract filtrate was filtered over a pad of anhydrous
MgSO4/silica gel (1:3) in a fritted funnel. The resulting red solution
7.30–7.21 (m, 3H), 7.14–6.96 (m, 6H), 6.89 (s, 1H, NH), 5.58 (s,
1H, NH), 2.39 (s, 2Me, 6H), 2.29 (s, 2Me, 6H), 1.63 (s, Me, 6H),
1.54 (s, 1H, OH) ppm. 13C NMR (75 MHz, CDCl3) d 166.5 (C@O),
164.9 (quaternary C), 156.8 (quaternary C), 151.4 (quaternary C),
148.8 (quaternary C), 147.2 (quaternary C), 139.7 (quaternary C),
137.9 (CH), 131.1 (CH), 130.1 (CH), 129.9 (quaternary C), 129.7

A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
357
(quaternary C), 128.6 (CH), 127.5 (CH), 127.4 (quaternary C), 127.2
(CH), 127.0 (CH), 126.8 (CH), 126.4 (quaternary C), 124.7 (quater-
nary C), 124.7 (CH), 124.1 (CH), 123.1 (CH), 122.0 (quaternary C),
105.5 (quaternary C), 18.8 (2 ꢂ Me), 18.3 (2 ꢂ Me), 18.1 (2 ꢂ Me).
Anal. Calc. for C37H34N4O2 (566.7): C, 78.42; H, 6.05; N, 9.89. Found:
C, 78.36; H, 6.06; N, 9.87%.
ternary C), 135.6 (quaternary C), 134.9 (quaternary C), 132.7 (qua-
ternary C), 131.7 (CH), 129.11 (CH), 128.6 (CH), 127.54 (CH),
127.48 (quaternary C), 127.3 (CH), 126.8 (CH), 126.4 (CH), 124.0
(CH), 122.0 (CH), 112.9 (quaternary C), 57.34 (OMe), 18.8
(2 ꢂ Me), 18.3 (2 ꢂ Me), 18.1 (2 ꢂ Me). Anal. Calc. for C38H36N4O3
(596.7): C, 76.49; H, 6.06; N, 9.39. Found: C, 76.41; H, 6.02; N,
9.34%.
4.3. N-(2,6-Dimethylphenyl)-2-(2,6-dimethylphenylamino)-2-[2-(2,6-
dimethylphenyl)-7-methoxy-1-oxo-1,2-dihydro-pyrrolo[3,4-
b]quinolin-3-ylidene]-acetimidic acid (4b)
4.6. General Procedure of the ethyl esterification of acetamidic acids
(6a–b)
M.p.: 211–213 °C. IR (cmꢁ1):
(C@N) 1668. 1H NMR (200 MHz, CDCl3) d 8.79 (d, 1H, quinol-H4),
m
(OH),
mNH) 3420, 3232 b,
m(C@O),
Tl(TfO) (374 mg, 1.06 mmol) and EtOH (one drop) were added
to a solution of 3a–b (1.06 mmol) in CH2Cl2 (20 ml). The resulting
black suspension was stirred for 20 h and filtered over Celite, and
the yellow filtrate was concentrated and applied to a preparative
TLC plate (eluant: n-hexane/Et2O, 1:2), where two main yellow
bands separated. From the band at Rf = 0.25 a 2:1 mixture of
5a–b and 4a–b was obtained in moderate yield. The band at
Rf = 0.62 was collected and extracted with Me2CO (30 ml). The
extract was treated with anhydrous MgSO4 for 1 h, filtered and
evaporated to dryness, affording the yellow ester 6a–b in low
yields (18–19%).
m
4
3
8.42 (dd, 1H, JHH = 1.6, JHH = 8.7 Hz, quinol-H8), 7.97 (d, 1H,
3
3JHH = 8.7 Hz, quinol-H5), 7.73 (dd, 1H, JHH = 8.7 and 6.8 Hz, qui-
3
nol-H7), 7.43 (dd, 1H, JHH = 8.7 and 6.8 Hz, quinol-H6), 7.3–7.2
(m, 3H), 7.14–6.95 (m, 6H), 5.58 (s, 1H, NH), 3.96 (s, 3H, OMe),
2.39 (s, 2Me, 6H), 2.29 (s, 2Me, 6H), 1.63 (s, Me, 6H), 1.54 (s, 1H,
OH) ppm. 13C NMR (75 MHz, CDCl3) d 166.5 (C@O), 164.9 (quater-
nary C), 156.8 (quaternary C), 151.4 (quaternary C), 148.8 (quater-
nary C), 147.2 (quaternary C), 139.7 (quaternary C), 137.9 (CH),
131.1 (CH), 130.1 (CH), 129.9 (quaternary C), 129.7 (quaternary
C), 128.6 (CH), 127.5 (CH), 127.4 (quaternary C), 127.2 (CH),
127.0 (CH), 126.8 (CH), 126.4 (quaternary C), 124.7 (quaternary
C), 124.7 (CH), 124.1 (CH), 123.1 (CH), 122.0 (quaternary C),
105.5 (quaternary C), 57.34 (OMe), 18.8 (2 ꢂ Me), 18.3 (2 ꢂ Me),
18.1 (2 ꢂ Me). Anal. Calc. for C38H36N4O3 (596.7): C, 78.49;
H,6.06; N, 9.39. Found: C, 78.46; H, 6.04; N, 9.36%.
4.7. N-(2,6-Dimethylphenyl)-2-(2,6-dimethylphenylamino)-2-[2-(2,6-
dimethylphenyl)-1-oxo-1,2-dihydro-pyrrolo[3,4-b]quinolin-3-
ylidene]acetimidic acid ethyl ester (6a)
A suspension solution of 3a (871.32 mg, 1.06 mmol) in CH2Cl2
(20 ml) was used under the reaction conditions to produce 6a in
4.4. N-(2,6-Dimethylphenyl)-2-(2,6-dimethylphenylamino)-2-[2-(2,6-
dimethylphenyl)-1-oxo-1,2-dihydro-pyrrolo[3,4-b]quinolin-3-
ylidene]-acetamide (5a)
the yield 122 mg, 19%. M.p.: 210–212 °C. IR (cmꢁ1):
m
(NH) 3384,
m
(C@O), m
(C@N) 1698, 1694, 1660. 1H NMR (200 MHz, CDCl3) d
4
3
8.86 (d, 1H, quinol-H4), 8.34 (dd, 1H, JHH = 1.6, JHH = 8.4 Hz, qui-
nol-H8), 7.87 (d, 1H, JHH = 8.4 Hz, quinol-H5), 7.73 (dd, 1H,
3
M.p.: 146–148 °C. IR (cmꢁ1):
(C@O) 1698,
(C@N), 1668. 1H NMR (200 MHz, CDCl3) d 8.77 (d,
1H, quinol-H4), 8.37 (dd, 1H, JHH = 1.6, JHH = 8.6 Hz, quinol-H8),
m(NH) 3388, 3366, 3262 broad,
3JHH = 8.4 and 6.8 Hz, quinol-H7), 7.45 (dd, 1H, JHH = 8.4 and
3
m
m
6.8 Hz, quinol-H6), 7.10–7.05 (m, 3H), 6.80–6.69 (m, 6H), 4.79 (s,
4
3
2
NH, 1H), 4.39 (q, CH2Me, 2H, JHH = 7 Hz), 2.22 (s, 2 ꢂ Me, 6H),
3
3
2
7.97 (d, 1H, JHH = 8.6 Hz, quinol-H5), 7.73 (dd, 1H, JHH = 8.6 and
1.48 (bs, 4 ꢂ Me, 12H), 1.39 (t, CH2Me, 3H, JHH = 7 Hz) ppm. Anal.
3
6.9 Hz, quinol-H7), 7.43 (dd, 1H, JHH = 8.6 and 6.8 Hz, quinol-H6),
Calc. for C39H38N4O2 (594.7): C, 78.76; H,6.44; N, 9.42. Found: C,
78.74; H, 6.22; N, 9.35%.
7.30–7.21 (m, 3H), 7.14–6.96 (m, 6H), 6.89 (s, 1H, NH), 5.07 (s,
1H, NH), 2.44 (s, 2Me, 6H), 2.29 (s, 2Me, 6H), 2.02 (s, Me, 6H)
ppm. 13C NMR (75 MHz, CDCl3) d 165.8 (C@O), 162.6 (C@O),
157.8 (quaternary C), 147.8 (quaternary C), 146.8 (quaternary C),
139.8 (quaternary C), 139.6 (quaternary C), 137.8 (CH), 135.9 (qua-
ternary C), 135.7 (quaternary C), 135.6 (quaternary C), 134.9 (qua-
ternary C), 132.7 (quaternary C), 132.1 (CH), 131.9 (CH), 129.14
(CH), 129.11 (CH), 128.6 (CH), 127.54 (CH), 127.48 (quaternary
C), 127.3 (CH), 126.8 (CH), 126.4 (CH), 124.0 (CH), 122.0 (CH),
112.9 (quaternary C), 18.8 (2 ꢂ Me), 18.3 (2 ꢂ Me), 18.1 (2 ꢂ Me).
Anal. Calc. for C37H34N4O2 (566.7): C, 78.42; H, 6.05; N, 9.89. Found:
C, 78.31; H, 6.12; N, 9.84%.
4.8. N-(2,6-Dimethylphenyl)-2-(2,6-dimethylphenylamino)-2-[2-(2,6-
dimethylphenyl)-7-methoxy-1-oxo-1,2-dihydro-pyrrolo[3,4-
b]quinolin-3-ylidene]acetimidic acid ethyl ester (6b)
A suspension solution of 3b (903.12 mg, 1.06 mmol) in CH2Cl2
(20 ml) was used under the reaction conditions to produce 6b in
the yield 120 mg, 18%. M.p.: 206–208 °C. IR (cmꢁ1):
m
(NH) 3384,
m
(C@O), m
(C@N) 1698, 1694, 1660. 1H NMR (300 MHz, CDCl3) d
4
3
8.86 (d, 1H, quinol-H4), 8.34 (dd, 1H, JHH = 1.6, JHH = 8.4 Hz, qui-
nol-H8), 7.87 (d, 1H, JHH = 8.4 Hz, quinol-H5), 7.73 (dd, 1H,
3
3
3JHH = 8.4 and 6.8 Hz, quinol-H7), 7.45 (dd, 1H, JHH = 8.4 and
4.5. N-(2,6-Dimethylphenyl)-2-(2,6-dimethylphenylamino)-2-[2-(2,6-
dimethylphenyl)-7-methoxy-1-oxo-1,2-dihydro-pyrrolo[3,4-
b]quinolin-3-ylidene]-acetamide (5b)
6.8 Hz, quinol-H6), 7.10–7.05 (m, 3H), 6.80–6.69 (m, 6H), 4.79 (s,
2
NH, 1H), 4.39 (q, CH2, 2H, JHH = 7 Hz), 2.22 (s, 2 ꢂ Me, 6H), 1.48
2
(bs, 4 ꢂ Me, 12H), 1.39 (t, CH2Me, 3H, JHH = 7 Hz) ppm. Anal. Calc.
for C40H40N4O3 (624.8): C, 76.90; H, 6.45; N, 8.97. Found: C, 76.83;
H, 6.42; N, 9.02%.
Mp: 146–148 °C. IR (cmꢁ1):
(C@O) 1698,
(C@N), 1668. 1H NMR (200 MHz, CDCl3) d 8.77 (d,
1H, quinol-H4), 8.37 (dd, 1H, JHH = 1.6, JHH = 8.6 Hz, quinol-H8),
m(NH) 3388, 3366, 3262 broad,
m
m
4
3
4.9. X-ray crystallographic studies
3
3
7.97 (d, 1H, JHH = 8.6 Hz, quinol-H5), 7.73 (dd, 1H, JHH = 8.6 and
3
6.9 Hz, quinol-H7), 7.43 (dd, 1H, JHH = 8.6 and 6.8 Hz, quinol-
Details of data collection and refinement are given in Table 1.
The crystal structures from the single-crystal X-ray diffraction
studies for 2a, 3a and 3b were carried out on a Bruker SMART
H6),7.30–7.21 (m, 3H), 7.14–6.96 (m, 6H), 6.89 (s, 1H, NH), 5.07
(s, 1H, NH), 3.96 (s, 3H, OMe), 2.44 (s, 2Me, 6H), 2.29 (s, 2Me,
6H), 2.02 (s, Me, 6H), ppm. 13C NMR (75 MHz, CDCl3) d 165.8
(C@O), 162.6 (C@O), 158.8 (quaternary C), 154.8 (quaternary C),
148.8 (quaternary C), 143.8 (quaternary C), 139.8 (quaternary C),
139.6 (quaternary C), 136.9 (CH), 135.9 (quaternary C), 135.7 (qua-
1000 CCD diffractometer with graphite-monochromated Mo K
a
radiation (k = 0.71073 Å). Cell parameters were obtained by global
refinement of the positions of all collected reflections. Intensities
were corrected for Lorentz and polarization effects and empirical

358
A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
Table 1
Details of data collection and structure refinement for the complexes {Pd[C9H5-CHO(3)]Cl(PPh3)}2 2a, {PdCl[(C@N-Xy)2-(C-NHXy) (CNXy)C9H5N-(3)-CO]} 3a and {PdCl[(C@N-
Xy)2-(C-NHXy) (CNXy) 6-MeO-C9H5N-(3)-CO]}3b.
2a ꢀ CH2Cl2
3a ꢀ CH2Cl2
3b ꢀ C2H6O ꢀ CH2Cl2
Empirical formula
E. F. as X-ray measure
Formula weight
Temperature (K)
Wavelength (Å)
Crystal habit
Crystal system
Space group
C56H42Cl2N2O2P2Pd2
C57H44Cl4N2O2P2Pd2
1205.48
133(2)
0.71073
C46H42ClN5OPd
C47H44Cl3N5OPd
907.62
133(2)
0.71073
red tablet
monoclinic
P21/c
C47H43ClN5O2Pd
C50H51Cl3N5O3Pd
982.71
100(2)
0.71073
red prism
monoclinic
P2(1)/c
yellow rectangular prim
triclinic
ꢀ
P1
Unit cell dimensions
a (Å)
b (Å)
11.8384(11)
13.451(2)
17.804(3)
106.116(11)
96.793(15)
111.512(12)
2456.0(6)
11.7167(8)
20.1516(14)
18.7484(12)
90
108.055(4)
90
8.3018(3)
19.8319(8)
27.3429(11)
90
95.2830(10)
90
4482.6(3)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
4208.7(5)
Z
2
4
4
Dcalc (Mg/m3)
1.630
1.062
1212
1.432
0.674
1864
0.25 ꢂ 0.19 ꢂ 0.10
1.53–30.04
ꢁ16 6 h 6 16,
ꢁ28 6 k 6 28,
ꢁ26 6 l 6 26
66861
1.456
0.642
2028
Absorption coefficient (mmꢁ1
F(000)
)
Crystal size (mm3)
0.36 ꢂ 0.15 ꢂ 0.11
0.25 ꢂ 0.15 ꢂ 0.14
h Range for data collection (°)
Index ranges
1.23–30.04
1.81–27.10
ꢁ16 6 h 6 16,
ꢁ18 6 k 6 18,
ꢁ25 6 l 6 25
46379
ꢁ10 6 h 6 10,
ꢁ25 6 k 6 25,
ꢁ35 6 l 6 34
50825
Reflections collected
Independent reflections (Rint
Completeness to h = 30.00° (%)
Absorption correction
Maximum and minimum transmission
Refinement method
)
14268 (0.0293)
99.4
numerical
0.9069 and 0.7461
full-matrix least-squares on F2
14268/0/622
1.029
12314 (0.0476)
100.0
numerical
0.9387 and 0.8509
full-matrix least-squares on F2
12314/0/526
0.982
9847 (0.0231)
99.7
semi-empirical from equivalents
0.9155 and 0.8559
full-matrix least-squares on F2
9847/32/571
1.065
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.0251, wR2 = 0.0630
R1 = 0.0335, wR2 = 0.0664
0.997 and ꢁ0.960
R1 = 0.0306, wR2 = 0.0724
R1 = 0.0478, wR2 = 0.0778
1.037 and ꢁ0.887
R1 = 0.0352, wR2 = 0.0909
R1 = 0.0395, wR2 = 0.0938
1.671 and ꢁ0.527
Largest difference in peak and hole
(e Åꢁ3
)
absorption. The structures were solved by direct methods and re-
fined by full-matrix least-squares on F2. All non-hydrogen atoms
were refined anisotropically. All hydrogen atoms placed in calcu-
lated positions. Structure solution and refinement were performed
by using the SHELXL-97 package. [71] Crystal data and processing
parameters for 2a, 3a and 3b are summarized in Table 1.
Appendix A. Supplementary data
CCDC 680962, 680963, 680964 contain the supplementary crys-
tallographic data for 2a, 3a, 3b. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: de-
posit@ccdc.cam.ac.uk. 1H and 31P NMR spectra for compounds 2a,
3a and 3b. Atomic coordinates, bond lengths, bond angles and
thermal parameters have been deposited at the Cambridge Crystal-
lographic Data Centre (CCDC). Supplementary data associated with
this article can be found, in the online version, at doi:10.1016/
j.poly.2008.10.054.
5. Conclusion
We successfully developed a new type of iminoacyl quinolinyl
palladium complexes and palladacycles that allows the prepara-
tion of new carbocycles via a depalladation reaction. Overall, this
methodology provides an alternative approach to novel quinolinyl-
palladium complexes and amide 5a–b or imidic acid 4a–b from
three simple and readily available building blocks via a one-pot,
multi-component process. These novel arylpalladium complexes
are air- and moisture stable, and further scope of this class of aryl-
palladium complexes and applications are currently under investi-
gation in our laboratory.
References
[1] R.F. Heck, Palladium Reagents in Organic Synthesis, Academic Press, New York,
1985.
[2] J.F. Hartwig, Angew. Chem., Int. Ed. 37 (1998) 2047.
[3] A.-S.S. Hamad Elgazwy, Appl. Organomet. Chem. 21 (12) (2007) 1041.
[4] A.-S.S. Hamad Elgazwy, Monatshefte Chem. 139 (11) (2008) 1285–1297.
[5] J. Tsuji, Palladium Reagents and Catalysis, Wiley, Chichester, UK, 1995.
[6] J.P. Wolfe, S. Wagaw, J.-F. Marcoux, S.L. Buchwald, Acc. Chem. Res. 31 (12)
(1998) 805.
Acknowledgments
[7] M. Shibasaki, E.M.J. Vogl, Organomet. Chem. 576 (1–2) (1999) 1.
[8] O. Loiseleur, M. Hayashi, M. Keenan, N. Schmees, A.J. Pfaltz, Organomet. Chem.
576 (1–2) (1999) 16.
[9] W.A. Herrmann, V.P.W. Bohm, C.-P.J. Reisinger, Organomet. Chem. 576 (1–2)
(1999) 23.
[10] S.J. Cacchi, Organomet. Chem. 576 (1–2) (1999) 42.
[11] R.C. Larock, J. Organomet. Chem. 576 (1–2) (1999) 111.
[12] A. Suzuki, J. Organomet. Chem. 576 (1–2) (1999) 147.
[13] J. Dupont, M. Pfeffer, J. Spencer, Eur. J. Inorg. Chem. 8 (2001). 1917.
This work has been supported by the Ministry of Education and
Science Spain and FEDER (EU) during the sabbatical leave of the
author as a visiting professor. The author wishes to thank Professor
Peter G. Jones’ Institut für Anorganische und Analytische Chemie
der Technischen Universität, Postfach 3329, 38023 Braunschweig,
Germany for the measurement of the single crystal by X-ray
analysis.

A.-S.S. Hamad Elgazwy / Polyhedron 28 (2009) 349–359
359
[14] A.C. Cope, E.C. Friedrich, J. Am. Chem. Soc. 90 (1968) 909.
[15] H. Alper, J. Organomet. Chem. 61 (1973) C62.
[46] E. Valencia, V. Fajardo, A.J. Freyer, M. Shamma, Tetrahedron Lett. 26 (8) (1985)
993.
[16] J. Dehand, A. Mauro, H. Ossor, M. Pfeffer, R.H.deA. Santos, J.R. Lechat, J.
Organomet. Chem. 250 (1) (1983) 537.
[47] E.C. Taylor, L.D. Jennings, Z. Mao, B. Hu, J.-G. Jun, P. Zhou, J. Org. Chem. 62
(1997) 5392.
[17] H.M. McPherson, J.L. Wardell, Inorg. Chim. Acta 75 (1983) 37.
[48] J.M. Thompson, R.C. Heck, J. Org. Chem. 40 (1975) 2667.
[49] A. Couture, E. Deniau, P. Grandclaudon, Tetrahedron 53 (30) (1992) 10313.
[50] D.L. Comins, S.P. Joseph, Y.-M. Zhang, Tetrahedron Lett. 37 (6) (1996) 793.
[51] S. Guha, A.K. Mukherjee, M.W. Khan, N.G. Kundu, Acta Crystallogr., Sect. C C55
(5) (1999) 818.
[52] N.G. Kundu, M.W. Khan, R. Mukhopadhyay, Tetrahedron 55 (42) (1999) 12361.
[53] W. Kantlehner, W.W. Mergen, in: A.R. Katritzky, O.C. Meth-Cohn, W. Rees
(Eds.), Comprehensive Organic Functional Group Transformations, Pergamon
Press, Oxford, 1995, p. 685. vol. 5.
[18] Jairton
Dupont,
Michel
Pfeffer
(Eds.),
Palladacycles:
Synthesis,
Co.
Characterization and Applications, 2008, WILEY-VCH Verlag GmbH
KGaA, Weinheim.
[19] Y. Yamamoto, H. Yamazaki, Synthesis 11 (1976). 750.
[20] K. Gehrig, A.J. Klaus, P. Rys, Helv. Chim. Acta 66 (8) (1983) 2603.
[21] A. Albinati, P.S. Pregosin, R. Rüedi, Helv. Chim. Acta 68 (7) (1985) 2046.
[22] R. Bertani, C.B. Castellani, B. Crociani, J. Organomet. Chem. 269 (1) (1984) C15.
[23] K. Suzuki, H. Yamamoto, Inorg. Chim. Acta 208 (2) (1993) 225.
[24] A.C. Albeniz, N.M. Catalina, P. Espinet, R. Redon, Organometallics 18 (26)
(1999) 5571.
&
[54] J. Vicente, J.A. Abad, E. Martínez-Viviente, M.C. Ramírez de Arellano, P.G. Jones,
Organometallics 19 (2) (2000) 752.
[25] E.C. Constable, Polyhedron 3 (9–10) (1984) 1037.
[26] M.I. Bruce, Angew. Chem., Int. Ed. Engl. 16 (2) (1977) 73.
[27] C. Anklin, P.S. Pregosin, F. Bachechi, P. Mura, L. Zambonelli, J. Organomet.
Chem. 222 (1) (1981) 175.
[55] A. Albinati, C.G. Anklin, F. Ganazzoli, H. Rugg, P.S. Pregosin, Inorg. Chem. 26
(1987) 503.
[56] K. Isobe, K. Nanjo, Y. Nakamura, S. Kawaguchi, Bull. Chem. Soc. Jpn. 59 (7)
(1986) 2141.
[28] H. Motschi, P.S. Pregosin, H. Riiegger, J. Organomet. Chem. 193 (3) (1980) 397.
[29] C.G. Anklin, P.S. Pregosin, J. Organomet. Chem. 243 (1) (1983) 101.
[30] E.F. Landvatter, T.B. Rauchfuss, Organometallics 193 (1982) 506.
[31] A.-S.S. Hamad Elgazwy, Tetrahedron 59 (38) (2003) 7445.
[32] J. Dupont, C.S. Consorti, J. Spencer, Chem. Rev. 105 (6) (2005) 2527.
[33] F.E. Ziegler, L. Chliwner, K.W. Fowler, S.J. Kanfer, S.J. Kuo, N.D. Sinha, J. Am.
Chem. Soc. 102 (1980) 790.
[34] K. Tomioka, T. Ishiguro, H. Mizuguchi, N. Komeshima, K. Koga, S. Tsukagoshi, T.
Tsuruo, T. Tashiro, S. Tanida, T. Kishi, J. Med. Chem. 34 (1) (1991) 54.
[35] United States Patent 3974165.
[57] J. Vicente, J.A. Abad, K.F. Shaw, J. Gil-Rubio, M.C. Ramirez de Arellano, P.G.
Jones, Organometallics 16 (1997) 4557.
[58] J. Vicente, J.A. Abad, A.D. Frankland, J. Lopez-Serrano, M.C. Ramirez de Arellano,
P.G. Jones, Organometallics 21 (2002) 272.
[59] V. Durá-Víla, D.M.P. Mingos, R. Vilar, A.J.P. White, D.J. Williams, J. Organomet.
Chem. 600 (1–2) (2000) 198.
[60] S. Otsuka, Y. Tatsuno, K. Ataka, J. Am. Chem. Soc. 93 (1971) 6705.
[61] M.F. Retting, E.A. Kirk, P.M. Maitlis, J. Organomet. Chem. 111 (1) (1976) 113.
[62] J.R. Boehm, A.L. Balch, Inorg. Chem. 16 (4) (1977) 778.
[63] J. Vicente, J.A. Abad, E. Martinez-Viviente, P.G. Jones, Organometallics 21
(2002) 4454.
[36] United States Patent 4800203.
[37] V. Gein, E. Bezmaternykh, L. Gein, I. Krylova, Chem. Heterocycl. Compd. 40 (10)
(2004) 1332.
[38] E. Valencia, A.J. Freyer, M. Shamma, V. Fajardo, Tetrahedron Lett. 25 (6) (1984)
599.
[64] W. Kantlehner, W.W. Mergen, Comprehensive Organic Functional Group
Transformations, in: A.R. Katritzky, O.C. Meth-Cohn, W. Rees (Eds.),
Pergamon Press, Oxford, 1995, p. 685. vol. 5.
[65] A. Sygula, J. Chem. Res. (S) 2 (1989) 56.
[39] R. Alonso, L. Castedo, D. Domínguez, Tetrahedron Lett. 26 (24) (1985) 2925.
[40] C.J. Moody, G.J. Warellow, Tetrahedron Lett. 28 (48) (1987) 6089.
[41] F. Csende, Z. Szabo, G. Stajer, Heterocycles 36 (8) (1993) 1809.
[42] I. Takahashi, E. Hirano, T. Kawakami, H. Kitajima, Heterocycles 43 (11) (1996)
2343.
[43] J. Epsztajn, R. Grzelak, A. Jozwiak, Synthesis (10) (1996) 1212.
[44] S.M. Allin, C.J. Northfield, M.I. Page, A.M.Z. Slawin, Tetrahedron Lett. 39 (27)
(1998) 4905.
[66] J. Vicente, M.T. Chicote, C. Rubio, M.C. Ram´ırezde Arellano, P.G. Jones,
Organometallics 18 (1999) 2750.
[67] J. Vicente, A. Arcas, D. Bautista, P.G. Jones, Organometallics 16 (1997) 2127.
[68] R. E Marsh, Acta Crystallogr., Sect. B 53 (1997) 317.
[69] Y. Yamamoto, H. Yamazaki, Bull. Chem. Soc. Jpn. 58 (1985) 1843.
[70] F.H. Allen, O. Kennard, D.G. Watson, L. Brammer, A.G. Orpen, R. Taylor, J. Chem.
Soc., Perkin Trans. 2 (1987) S1.
[71] G.M. Sheldrick, SHELXTL-97. Program for the Refinement of Crystal Structures,
University of Gottingen, Germany, 1997.
[45] Z.-P. Zhuang, M.-P. Kung, M. Mu, H.-F. Kung, J. Med. Chem. 41 (2) (1998) 157.