Cyclopalladation of schiff bases from methyl esters of α-Amino acids. Unexpected activation of the O-Me bond with formation of a bianionic tridentate metallacycle

Article abstract of DOI:10.1021/om9009153

The action of palladium acetate on imines from methyl esters of the a-amino acids glycine, alanine, valine, and tyrosine is herein described. The reactivity of the new metallacycles obtained with phosphines and amines is also described, as well as the synthesis of isoquinolinium salts by insertion of diphenylacetylene into the Pd-C bond. Besides this, the unexpected activation of the Me-O bond of the ester group of the amino acid fragment is also reported, in a process that affords new cyclopalladated derivatives having the metalated molecule as a dianionic (C,N,O) ligand.

Full text of DOI:10.1021/om9009153

214 Organometallics 2010, 29, 214–225
DOI: 10.1021/om9009153
Cyclopalladation of Schiff Bases from Methyl Esters of r-Amino Acids.
Unexpected Activation of the O-Me Bond with Formation of a Bianionic
Tridentate Metallacycle
Joan Albert,*,† Margarita Crespo,† Jaume Granell,*,† Judit Rodrıguez,† Javier Zafrilla,†
´
‡
Teresa Calvet, Merce Font-Bardia, and Xavier Solans
‡
‡
ꢀ
†
´
ꢀ
Departament de Quımica Inorganica i Institut de Biomedicina (IBUB), Universitat de Barcelona,
‡
Martı i Franques, 1-11, 08028 Barcelona, Spain. and Departament de Cristal lografia, Mineralogia i
´
Dipoꢀsits Minerals, Universitat de Barcelona, Martı i Franques, s/n, 08028 Barcelona, Spain.
ꢀ
3
´
ꢀ
Received October 19, 2009
The action of palladium acetate on imines from methyl esters of the R-amino acids glycine, alanine,
valine, and tyrosine is herein described. The reactivity of the new metallacycles obtained with
phosphines and amines is also described, as well as the synthesis of isoquinolinium salts by insertion
of diphenylacetylene into the Pd-C bond. Besides this, the unexpected activation of the Me-O bond
of the ester group of the amino acid fragment is also reported, in a process that affords new
cyclopalladated derivatives having the metalated molecule as a dianionic (C,N,O) ligand.
Introduction
the metallacycles in many areas including organic synthesis,
catalysis, the design of new metallomesogens and antitumor-
al drugs, asymmetric synthesis, resolution of racemic li-
gands, intermolecular aromatic C-H bond activation, or
synthesis and reactivity of organometallic complexes with
biologically important ligands.2
There is growing interest in the synthesis, reactivity, and
applications of organometallic complexes with biologically
active ligands such as R-amino acids or biogenic amines,3
and the term bioorganometallic chemistry is used to describe
this research field on the border between biochemistry and
organometallic chemistry. R-Amino acids are highly versa-
tile ligands and can afford two classes of compounds: com-
plexes in which the amino acid is coordinated to an
organometallic fragment via their donor atoms (amino,
carboxylato, or other basic groups) and complexes in which
the amino acid is coordinated to the metal through a
carbon-metal bond, this last class being comparatively rare.
Some C-N chelates have been synthesized by metalation of
amino acid derivatives by palladium.4 The ortho-palladated
Cyclometalation reactions were one of the first known
examples of C-H bond activation, and cyclopalladated
complexes of a wide variety of ligands containing N, P, As,
O, or S as the heteroatom have been described.1 The cyclo-
metalation of N-donor ligands has been extensively studied
and has acquired great interest because of the application of
*Corresponding author. E-mail: jaume.granell@qi.ub.es; joan.albert@
qi.ub.es.
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pubs.acs.org/Organometallics
Published on Web 11/23/2009
2009 American Chemical Society

Article
Organometallics, Vol. 29, No. 1, 2010 215
Scheme 1
complexes of biologically active ligands are interesting be-
cause of their potential cytotoxic activity and because they
can be useful precursors to prepare functionalized deriva-
tives that potentially can present important biological effects
and that are not easily prepared by other methods.4,5
With these precedents in mind, and following our studies
on cyclometalation reactions,6 we focused our attention on
the action of palladium acetate on methyl esters of imines
from glycine, alanine, valine, and tyrosine and on the
reactivity of the metallacycles obtained.
of an aliphatic carbon-hydrogen bond (imine 1c) or by
activation of an aromatic carbon-hydrogen bond of the
tyrosine fragment (imine 1d); nevertheless overall NMR data
showed that only the endo-derivative was formed, which is
consistent with reports of the strong tendency of imines to form
endo-metallacycles. 8 The corresponding chloro-bridged cyclo-
palladated dimers 3 were also isolated by reaction between
acetato-bridged dimers and LiCl in acetone.
1
The H NMR spectra of compounds 2 produced broad
signals at room temperature, and the spectrum of compound
3a could not be recorded due to its insolubility. To complete
the characterization of the new metallacycles, mononuclear
compounds 4 and 7 were obtained in an NMR tube by
addition of a few drops of pyridine-D5 to CDCl3 solutions of
2 or 3, respectively. It should be noted that complete
racemization of the Schiff base takes place during the
cyclopalladation reaction, in acetic acid. To evaluate the
influence of the reaction conditions in the racemization
process, the cyclopalladation reaction was tried using more
mild conditions. We found that the imines could also be
metalated by carrying out the reaction in acetone at room
temperature for 5 days. As expected, under these reaction
conditions, the racemization of the imines was not as fast and
optically active compounds were obtained for ligands 1b, 1c,
and 1d (optical rotation: þ22.0, -18.1, and -45.0 for 2b, 2c,
and 2d, respectively). To evaluate the ee of 2, these dinuclear
cyclometalated complexes were reacted with (S)-(-)-R-methyl-
benzylamine in an NMR tube, to obtain 5 (Scheme 1).
Results and Discussion
Imines 1 were obtained following an analogous procedure
to that reported in the literature7 by condensation of the
corresponding amino acid with 4-chlorobenzaldehyde. All
attempts to metalate these ligands using, as a metalating
agent, mixtures of PdCl2/NaCl/NaAcO, in different reaction
conditions, were unsuccesful. Nevertheless, when these Schiff
bases were treated with palladium acetate in refluxing acetic
acid for 1 h, the corresponding endo acetato-bridged five-
membered cyclopalladated dimers 2 were obtained. Imines
1c and 1d can also afford the exo-metallacycles, by activation
(5) (a) Vicente, J.; Saura-Llamas, I.; Bautista, D. Organometallics
ꢁ
2005, 24, 6001. (b) Vicente, J.; Saura-Llamas, I.; García Lopez, J. A.
Organometallics 2009, 28, 448.
ꢁ
(6) (a) Capape, A.; Crespo, M.; Granell, J.; Vizcarro, A.; Zafrilla, J.;
Font-Bardia, M.; Solans, X. Chem. Commun. 2006, 4128. (b) Albert, J.;
ꢁ
Cadena, M.; Gonzalez, A.; Granell, J.; Solans, X.; Font-Bardia, M. Chem.;
ꢁ
(8) (a) Gomez, M.; Granell, J.; Martinez, M. J. Chem. Soc., Dalton
Eur. J. 2006, 12, 887. (c) Albert, J.; Bosque, R.; Cadena, M.; Delgado, S.;
Granell, J.; Muller, G.; Ordinas, J. I.; Font-Bardia, M.; Solans, X. Chem.;
Eur. J. 2002, 8, 2279. (d) Rodríguez, J.; Zafrilla, J.; Albert, J.; Crespo, M.;
Granell, J.; Teresa Calvet, T.; Font-Bardia, M. J. Organomet. Chem. 2009,
694, 2467.
ꢁ
Trans. 1998, 37. (b) Gomez, M.; Granell, J.; Martinez, M. Organometallics
1997, 16, 2539. (c) De Munno, G.; Ghedini, M.; Neve, F. Inorg. Chim. Acta
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1995, 239, 155. (d) Bosque, R.; Lopez, C.; Font-Bardia, M.; Solans, X. J.
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Chem. Soc., Dalton Trans. 1995, 4053. (e) Bosque, R.; Lopez, C.; Sales, J.
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(7) Belokon, Y. N.; Bhave, D.; D’Addario, D.; Groaz, E.; North, M.;
J. Organomet. Chem. 1995, 498, 147. (f) Bosque, R.; Lopez, C.; Sales, J.
Tagliazucca, V. Tetrahedron 2004, 60, 1849.
J. Chem. Soc., Dalton Trans. 1995, 2445.

216 Organometallics, Vol. 29, No. 1, 2010
Albert et al.
Scheme 2
The proton NMR spectra of these species show an ee of 40, 85,
and 45% for 5b, 5c, and 5d, respectively. This is not an
unexpected result bearing in mind the results reported for the
racemization of the amino acids.
nylphosphine-containing complexes 6 and 8, due to the
aromatic rings of the phosphine, indicates the cis disposition
of the phosphorus relative to the metalated carbon atom, and
the chemical shift of the phosphorus confirms this arrange-
ment.10 This arrangement is usual in cyclopalladated com-
pounds containing phosphines.11 IR spectra of 6 showed
Generally, free amino acids are difficult to racemize, and
some work has been undertaken to develop a simple and
economical method for the racemization of optically active
amino acids. It is known that heating optically active R-
amino acids in the presence of arylaldehydes effects racemi-
zation from the intermediate imines. Besides this, the race-
mization of a wide variety of optically active R-amino acids
was found to be greatly accelerated in acetic acid solution in
the presence of catalytic amounts of aromatic aldehydes.9
Reaction of dimers 2 or 3 with PPh3 afforded the mono-
nuclear complexes [PdX(C-N)(PPh3)], X = AcO or Cl
(compounds 6 and 8, respectively).
ν(CO2)asymm and ν(CO2)symm separated by 220-250 cm-1
,
consistent with unidentate acetato coordination.12
The structures of 3c and 8a were determined by X-ray
diffraction (Figures 1 and 2). The asymmetric unit of 3c
presents two independent molecules, which correspond to
the meso and rac forms of compound 3c. The crystal struc-
tures consist of discrete molecules separated by van der
Waals distances. The distances between palladium and
the coordinated atoms are similar to those reported
for analogous compounds (Table 1).13 In both cases, the
All the new cyclometalated compounds obtained were
characterized by elemental analysis, IR spectra, and proton
NMR spectra. In some cases, 2D-NMR experiments and
mass spectra were carried out to complete the characteriza-
tion. The high-field shift of the aromatic protons of the
palladated ring in the proton NMR spectra of complexes 4
and 7 indicates the cis disposition of the pyridine relative to
the metalated carbon atom. The proton bonded to the chiral
carbon atom of the amino acid fragment appears low field
shifted, in relation to free ligand, in all compounds contain-
ing a chloro ligand in the coordination sphere of the metal.
ꢁ
(10) (a) Albert, J.; Gomez, M.; Granell, J.; Sales, J.; Solans, X.
Organometallics 1990, 9, 1405. (b) Albert, J.; Granell, J.; Sales, J.;
Font-Bardia, M.; Solans, X. Organometallics 1995, 14, 1393.
(11) The destabilizing effect of two soft ligands in mutual trans
positions has been called antisymbiosis; see: (a) Davies, J. A.; Hartley,
F. R. Chem. Rev. 1981, 81, 79. (b) Pearson, R. G. Inorg. Chem. 1973, 12,
712. (c) Navarro, R.; Urriolabeitia, E. P. J. Chem. Soc., Dalton Trans. 1999,
4111. Recently the term transphobia has been proposed to describe the
difficulty of coordinating mutually trans phosphine and aryl ligands in
palladium complexes; see: (d) Vicente, J.; Abad, J. A.; Frankland, A. D.;
Ramírez de Arellano, M. C. Chem.;Eur. J. 1999, 5, 3066. (e) Vicente, J.;
Arcas, A.; Bautista, D.; Jones, P. G. Organometallics 1997, 16, 2127. (f)
Crespo, M.; Granell, J.; Solans, X.; Font-Bardia, M. J. Organomet. Chem.
2003, 681, 143.
(12) Deacon, G. B.; Phillips, R. J. Coord. Chem. Rev. 1980, 33, 227.
(13) (a) Naya, L.; Vazquez-Garcıa, D.; Lopez-Torres, M.; Fernandez,
A.; Vila, J. M.; Gomez-Blanco, N.; Fernandez, J. J. J. Organomet. Chem.
2008, 693, 685. (b) Albert, J.; D'Andrea, L.; Granell, J.; Tavera, R.; Font-Bardia,
M.; Solans, X. J. Organomet. Chem. 2007, 692, 3070. (c) Davies, D. L.;
Al-Duaij, O.; Fawcett, J.; Singh, K. J. Organomet. Chem. 2008, 693, 965. (d)
This can be explained by the existence of a C-H Cl
3 3 3
nonconventional hydrogen bond in these complexes. The
determination of the crystal structure of compounds 3c and
8a (see below) confirmed this interaction. The high-field shift
of the aromatic protons of the palladated ring in the triphe-
ꢁ
ꢁ ꢁ
´
ꢁ
ꢁ
ꢁ
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(9) (a) Grigg, R.; Gunaratne, H. Q. N. Tetrahedron Lett. 1983, 24,
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Zwanenburg, B. Tetrahedron 1997, 53, 9417. (c) Yamada, S.; Hongo, C.;
Yoshioka, R.; Chibata, I. J. Org. Chem. 1983, 48, 843.
Teijido, B.; Fernandez, A.; Lopez-Torres, M.; Castro-Juiz, S.; Suarez, A.;
Ortigueira, J. M.; Vila, J. M.; Fernandez, J. J. J. Organomet. Chem. 2000,
598, 71. (e) Bedford, R. B.; Cazin, C. S. J.; Coles, S. J.; Gelbrich, T.; Hursthouse,
M. B.; Veronique Scordia, V. J. Dalton Trans. 2003, 3350.
ꢁ
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Article
Organometallics, Vol. 29, No. 1, 2010 217
Figure 1. Molecular structure of compound 3c.
Figure 2. Molecular structure of compound 8a.
metallacycles that contain the imine functionality are planar
and the smallest angle in the coordination sphere of palla-
dium corresponds to the C-Pd-N bite angle, 80.9(3)° for 3c
and 80.57(12)° for 8a. For the molecules of compound 3c, the
palladium atom is in a square-planar environment, coordi-
nated to one carbon, two chlorine, and one nitrogen atom.
The Pd-Cl bonds trans to the Pd-C bond are significantly
longer than those trans to nitrogen, and this can be attributed
to the higher trans influence of the carbon. An intramole-
metallacycles 6c and 6d for 24 h. This reaction affords new
cyclopalladated derivatives by the activation of the O-Me
bond of the ester group of the R-amino acid fragment. These
new tridentate metallacycles were characterized by elemental
analysis, IR, MS, and NMR spectroscopy, and the structure
of 9c was also determined by X-ray diffraction (Figure 3).
The crystal structure consists of discrete molecules separated
by van der Waals distances. The distances between palladium
and the coordinated atoms are similar to those reported for
analogous compounds.15 The coordination plane shows a
slight tetrahedral distortion, the deviation from the mean plane
being 0.020, -0.023, -0.016, 0.008, and -0.021 A for Pd, C1,
N, P1, and O1, respectively. The metallacycle that contains the
CdN bond is quite planar, the deviation from the mean plane
being 0.038, 0,010, -0.039, -0.034, and -0.052 A for Pd, C6,
C7, C1, and N, respectively. In contrast, the cycle formed by
Pd, N, C8, C9, and O1 atoms shows a significant distortion
from planarity, due to the sp3 hybridization of O1 and C8
atoms, the deviation from the mean plane being 0.021, -0.104,
0.162, -0.147, and 0.069 A for Pd, N, C8, C9, and O1,
respectively.
Cyclopalladated compounds are valuable intermediates
for regioselective organic synthesis, and increasing attention
has been paid to insertion of alkynes into the Pd-C bond.
This reaction could also afford isoquinoline derivatives, and
the synthesis of such derivatives containing the R-amino acid
fragment seems interesting to us.1 It should be noted that N-
carboxymethylisoquinoline derivatives have been proposed
as new carriers for specific brain delivery.16 Nevertheless, all
the attempts to prepare the corresponding isoquinoline
cular C-H Cl interaction between the proton bonded to
3 3 3
the chiral carbon atom of the amino acid fragment and the
bridging chlorine atom is observed, with bond distances in
the range 2.584-2.661 A. For compound 8a the palladium
atom is in a square-planar environment, coordinated to
carbon, chlorine, nitrogen, and phosphorus atoms.
The coordination plane shows a slight tetrahedral distortion,
the deviation from the mean plane being 0.014,
0,013, -0.020, 0.017, and -0.010 A for Pd, C1, N, P, and
Cl1, respectively. The phosphorus and nitrogen atoms adopt
a trans arrangement, the metallacycle contains the CdN
bond, and the imine is in the E-form. An intramolecular
C-H Cl interaction between one of the protons of the
3 3 3
CH2 group of the amino acid fragment and the chlorine atom
bonded to the metal is observed, with a bond distance of
2.645 A.
There are few reports about the activation of C-O bonds
by group 10 transition metal compounds: Milstein et al. have
reported the O-Me bond activation of a methoxy-substi-
tuted benzyl phosphine, 14a Colbran et al. have described the
O-metalation of 2-(2,5-dimethoxyphenyl)-1,10 phenantro-
line by palladium(II) with formation of the corresponding O,
N,N coordination compound, 14b and we have reported the
activation of an ortho O-Me bond of the imine (E)-N-(2,4,
6-trimethoxybenzylidene)-1-phenylethanamine by reacting
the cyclopalladated dinuclear complex of this ligand with
triphenylphosphine.10b
(15) (a) Shi, P.-Y.; Liu, Y.-H.; Peng, S.-H.; Liu, S.-T. Organometallics
2002, 21, 3203. (b) Das, S.; Pal, S. J. Organomet. Chem. 2004, 689, 352. (c)
Neogi, D. N.; Das, P.; Biswas, A. N.; Bandyopadhyay, P. Polyhedron 2006,
25, 2149.
(16) Mahmoud, S.; Aboul-Fadl, T.; Shesha, M.; Farag, H.; Mou-
hamed, A. I. Arch. Pharm. Pharm. Med. Chem. 2003, 336, 573.
(17) (a) Spencer, J.; Pfeffer, M.; Kyritsakas, N.; Fischer, J. Organo-
metallics 1995, 14, 2214. (b) Wu, G.; Rheingold, A. L.; Heck, R. F. J. Org.
Chem. 1988, 53, 3238. (c) Spencer, J.; Pfeffer, M.; de Cian, A.; Fischer, J. J.
Org. Chem. 1995, 60, 1005. (d) Gies, A. E.; Pfeffer, M.; Sirlin, C.; Spencer, J.
Eur. J. Org. Chem. 1999, 8, 1957. (e) Maassarini, F.; Pfeffer, M.; Le Borgne,
G. J. Chem. Soc., Chem. Commun. 1986, 488. (f) Vicente, J.; Saura-Llamas,
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metallics 2009, 28, 4175.
Compounds 9c and 9d (Scheme 1), having the metalated
molecule as a dianionic (C,N,O) ligand, were unexpectedly
obtained by refluxing acetone solutions of the corresponding
ꢁ
(14) (a) Weissman, H.; Simon, L. J. W.; Milstein, D. Organometallics
2004, 23, 3931. (b) Berthon, R. A.; Colbran, S. B.; Craig, D. C. Polyhedron
1992, 11, 243.

218 Organometallics, Vol. 29, No. 1, 2010
Table 1. Bond Distances (A) and Angles (deg) for Compounds 3c, 8a, 9c, and 12b
Albert et al.
˚
3c
8a
9c
12b
C1A-Pd1 = 1.986(8)
N8A-Pd1 = 2.033(7)
C1B-Pd2 = 1.976(9)
N(8B)-Pd(2) = 2.008(8)
C1C-Pd3 = 1.974(8)
N8C-Pd3 = 2.029(8)
C1D-Pd4 = 1.984(8)
N8D-Pd4 = 2.032(8)
Cl1-Pd1 = 2.322(2)
Pd-C1 = 2.039(3)
Pd1-C1 = 1.951(4)
N1-C10 = 1.323(4)
N1-C2 = 1.396(4)
N1-C11 = 1.494(4)
C2-C3 = 1.371(4)
C2-C15 = 1.487(4)
C3-C4 = 1.438(4)
C3-C21 = 1.488(4)
C4-C9 = 1.408(4)
C9-C10 = 1.397(5)
C4-C5 = 1.403(4)
C5-C6 = 1.369(4)
C6-Cl1 = 1.734(3)
C11-C12 = 1.520(5)
C11-C13 = 1.526(5)
C13-O1 = 1.201(4)
C13-O2 = 1.324(4)
O2-C14 = 1.448(5)
C15-C16 = 1.392(5)
C21-C22 = 1.389(5)
C10-N1-C2 = 121.3(3)
C10-N1-C11 = 120.1(3)
C2-N1-C11 = 118.6(3)
C3-C2-N1 = 119.6(3)
C3-C2-C15 = 122.9(3)
N1-C2-C15 = 117.3(3)
C2-C3-C4 = 120.2(3)
C2-C3-C21= 119.6(3)
C4-C3-C21 = 120.3(3)
C5-C4-C9 = 118.8(3)
C5-C4-C3 = 123.4(3)
C9-C4-C3 = 117.8(3)
C6-C5-C4 = 118.6(3)
C5-C6-Cl1 = 118.6(3)
C10-C9-C4 = 119.3(3)
N1-C10-C9 = 121.7(3)
Pd-N = 2.110(3)
Pd1-N = 2.038(3)
Pd-P = 2.2760(10)
Pd-Cl1 = 2.3633(13)
N-C7 = 1.254(4)
Pd1-O1 = 2.094(3)
Pd1-P1 = 2.2803(16)
O1-C9 = 1.345(5)
N-C8 = 1.453(5)
N-C7 = 1.254(4)
C1-C6 = 1.414(4)
N-C8 = 1.455(4)
C6-C7 = 1.470(5)
C1-C6 = 1.412(5)
C8-H8A = 0.9700
C6-C7 = 1.435(5)
Cl1-Pd2 = 2.450(2
Cl1-H8A = 2.645
C8-C9 = 1.521(5)
Cl2-Pd2 = 2.331(2)
C1-Pd-N = 80.57(12)
C1-Pd-P = 97.70(9)
N-Pd-P = 177.57(7)
C1-Pd-Cl1 = 170.14(9)
N-Pd-Cl1 = 89.57(8)
P-Pd-Cl1 = 92.16(4)
C7-N-C8 = 119.6(3)
C7-N-Pd = 113.4(2)
C8-N-Pd = 126.5(2)
C6-C1-Pd = 111.8(2)
C1-C6-C7 = 115.0(3)
N-C7-C6 = 119.0(3)
N-C8-H8A = 109.8
C8-H8A-Cl1 = 116.730
C1-Pd1-N = 81.34(15)
C1-Pd1-O1 = 161.40(13)
N-Pd1-O1 = 177.10(10)
C1-Pd1-P1 = 95.78(12)
N-Pd1-P1 = 177.10(10)
O1-Pd1-P1 = 102.65(9)
C9-O1-Pd1 = 113.2(2)
C7-N-C8 = 130.5(3)
C7-N-Pd1 = 114.8(3)
C8-N-Pd1 = 114.6(2)
C6-C1-Pd1 = 111.6(3)
C1-C6-C7 = 115.8(3)
N-C7-C6 = 115.8(4)
N-C8-C9 = 108.3(3)
O1-C9-C8 = 115.7(3)
Cl2-Pd1 = 2.458(2)
Cl3-Pd4 = 2.326(2)
Cl3-Pd3 = 2.458(2)
Cl4-Pd3 = 2.325 (2)
Cl4-Pd4 = 2.464(2)
Cl1-H9B = 2.594
Cl2-H9A = 2.661
Cl3-H9C = 2.584
Cl4-H9D = 2.600
Pd1-Cl1-Pd2 = 93.90(7)
Pd2-Cl2-Pd1 = 93.50(7)
Pd4-Cl3-Pd3 = 92.96(7)
Pd3-Cl4-Pd4 = 92.82(7)
C1A-Pd1-N8A = 80.9(3)
C1A-Pd1-Cl1 = 94.7(2)
N8A-Pd1-Cl1 = 175.1(2)
C1A-Pd1-Cl2 = 178.7(3)
N8A-Pd1-Cl2 = 98.6(2)
Cl1-Pd1-Cl2 = 85.89(8)
C1B-Pd2-N8B = 81.5(3)
C1B-Pd2-Cl2 = 95.3(3)
N8B-Pd2-Cl2 = 176.7(2)
C1B-Pd2-Cl1 = 176.8(3)
N8B-Pd2-Cl1 = 97.4(2)
with solvent molecules as ligands, react more easily with
alkynes. This fact prompted us to obtain such ionic
compounds in solution. The reactions of halo palladium
complexes with silver salts of weakly coordinating anions in
solvents with poor donor abilities, especially when they are
not thoroughly anhydrous, facilitate the direct synthesis
of aqua palladium complexes.18 Thus, the action of AgBF4
on acetone solutions of the cyclometalated compounds 3
precipitates AgCl, affording solutions containing cyclopal-
ladated ionic species with coordinated water molecules
10a-d (Scheme 2). These compounds were characterized by
NMR spectroscopy. The methinic proton signal appears low
field shifted in all compounds, in agreement with the ionic
structure proposed. The proton bonded to the chiral atom of
the amino acid fragment appears high field shifted in
all cases, in relation to compounds 3, showing that there is
no intramolecular hydrogen-chloro bond in these com-
plexes, thus confirming that the chloro ligand has been
removed from the coordination sphere of the metal. Besides
this, the broadening of the signals assigned to protons 1 and 5
suggests the existence of a fast exchange of the solvent
molecules coordinated to palladium. The signals assigned
to coordinated water appear in the range 3.69-3.06 and are
low field shifted when the spectra are recorded at 220 K, in
agreement with previous results.18
Figure 3. Molecular structure of compound 9c.
The addition of 1,2-bis(diphenylphosphino)ethane (dppe),
in a 1:1 molar ratio, to an acetone solution of these species
affords, as expected, the ionic compounds 11 in good yields.
derivatives, in different reaction conditions, by insertion of
diphenylacetylene in the Pd-carbon bond of compounds 2
or 3 were unsuccessful.
It is accepted that insertion of alkynes takes place after the
alkyne coordination to the metal.1,17 Thus, cationic species,
(18) Vicente, J.; Arcas, A. Coord. Chem. Rev. 2005, 249, 1135.

Article
Organometallics, Vol. 29, No. 1, 2010 219
recorded as KBr disks on a FTIR Nicolet 5700 spectrometer.
MALDI TOF(þ) spectra were recorded on a VOYAGER-DE-
RP spectrometer (with a dithranol or a 2,5-dihydroxybenzoic
acid matrix). CI spectra were recorded on a ThermoFinnigan
TRACE DSQ spectrometer, using NH3 as reactive gas, and
electrospray spectra on an Agilent LC/MSD-TOF spectro-
meter, equipped with a dual sprayer source using purine
(m/z = 121.050873) and HP-0921 (m/z = 922.009798) as
internal reference masses.
Preparation of Compounds. Synthesis of Imines. 4-ClC6-
H3CHdNCH2CO2Me (1a). A mixture of glicine methyl ester
hydrochloride (1.0 g, 7.96 mmol), 4-chlorobenzaldehyde
(1.120 g, 7.96 mmol), triethylamine (0.806 g, 7.96 mmol), and
anhydrous magnesium sulfate (1.5 g, 12.5 mmol) was refluxed
for 2 h in dichloromethane. After the reaction mixture was
cooled to room temperature, the undissolved materials were
removed by filtration, washed with dichloromethane, and dis-
carded. The filtrate was concentrated to dryness on a rotatory
evaporator to give a white solid. The white solid was dissolved in
benzene and filtered, and the resulting solution was concen-
trated to dryness on a rotatory evaporator to give compound 1a,
Figure 4. Molecular structure of the organic cation of com-
pound 12b.
1
1.672 g (99%), as a yellow oily material. H NMR (200 MHz,
CDCl3, 298 K), δ (ppm): 8.26 (s, 1H, H4), 7.72 (d, 2H, JHH
1H and 31P NMR data agree with the ionic stucture proposed
for compounds 11.19
=
8.5, H2), 7.40 (d, 2H, JHH = 8.5, H1), 4.41 (s, 2H, CH2), 3.78 (s,
3H, CO2Me). IR (KBr), ν (cm-1): ν(CdO) = 1737, ν(CdN) =
1645. MS-CI, m/z: [M þ H]þ = 211.0.
More interesting, the reaction of the ionic compounds
10a-d with diphenylacetylene in refluxing nitromethane
afforded the isoquinolinium salts 12a-d by insertion of the
alkyne into the Pd-C bond (Scheme 2). All these organic
compounds were characterized by elemental analysis, IR,
MS, and NMR spectroscopy, and the structure of 12b was
also determined by X-ray diffraction (Figure 4), confirming
the structure proposed and showing that the bond distances
and angles are similar to those reported for related com-
pounds.20
In conclusion we have synthesized new metallacycles by
cyclopalladation of Schiff bases from the methyl esters of the
R-amino acids glycine, alanine, valine, and tyrosine. We also
report the unexpected selective activation of the O-Me
bond, with formation of a bianionic tridentate metallacycle,
as well as the synthesis of isoquinolinium salts by insertion of
diphenylacetylene into the Pd-C bond of cyclopalladated
ionic complexes.
4-ClC6H3CHdNCH(Me)CO2Me (1b). A mixture of L-ala-
nine methyl ester hydrochloride (1.0 g, 7.16 mmol), 4-chloro-
benzaldehyde (1.003 g, 7.16 mmol), triethylamine (0.723 g,
7.16 mmol), and anhydrous magnesium sulfate (1.5 g, 12.5
mmol) was refluxed for 2 h in dichloromethane. After the
reaction mixture was cooled to room temperature, the undis-
solved materials were removed by filtration, washed with di-
chloromethane, and discarded. The filtrate was concentrated to
dryness on a rotatory evaporator to give an oily material, which
was dissolved in benzene and filtered, and the resulting solution
was concentrated to dryness on a rotatory evaporator to give
compound 1b, 1.374 g (85%), as a yellow oily material. 1H NMR
(200 MHz, CDCl3, 298 K), δ (ppm): 8.27 (s, 1H, H4), 7.71 (d, 2H,
JHH = 8.6, H2), 7.39 (d, 2H, JHH = 8.6, H1), 4.16 (q, 1H, JHH
=
6.8, H5), 3.75 (s, 3H, CO2Me), 1.53 (d, 3H, JHH
=
7.0, H6). IR (cm-1): ν(CdO) = 1733, ν(CdN) = 1647. MS-
CI (m/z): [M þ H]þ = 225.0. ee = 62%, [R]Na20 = -66.6.
4-ClC6H3CHdNCH(iPr)CO2Me (1c). A mixture of L-valine
methyl ester hydrochloride (1.0 g, 5.96 mmol), 4-chlorobenzal-
dehyde (0.840 g, 7.16 mmol), triethylamine (0.603 g, 5.96 mmol),
and anhydrous magnesium sulfate (1.5 g, 12.5 mmol) was
refluxed for 2 h in dichloromethane. After the reaction mixture
was cooled to room temperature, the undissolved materials were
removed by filtration, washed with dichloromethane, and dis-
carded. The filtrate was concentrated to dryness on a rotatory
evaporator to give an oily material, which was dissolved in
benzene and filtered, and the resulting solution was concen-
trated to dryness on a rotatory evaporator to give compound 1c,
Experimental Section
All solvents were dried and degassed by standard methods.
All chemicals were of commercial grade and used as received.
1H NMR spectra were registered on a Varian Gemini 200,
Varian Unity 300, and a Varian Mercury 400 instrument. 31P-
{1H} NMR spectra were recorded on a Bruker DRX 250
spectrometer, operating at 101.26 MHz. Chemical shifts (in
1
ppm) were measured relative to SiMe4 for H, to 85% H3PO4
for 31P, and to C6F6 for 19F. Abbreviations used: s = singlet;
d = doublet; t = triplet; q = quartet; m = multiplet; br =
broad; NMR labeling as shown in schemes. Microanalyses were
1
1.255 g (83%), as a white oily material. H NMR (200 MHz,
CDCl3, 298 K), δ (ppm): 8.20 (s, 1H, H4), 7.73 (d, 2H, JHH =
8.6, H2), 7.39 (d, 2H, JHH = 8.6, H1), 3.75 (s, 3H, CO2Me), 3.67
ꢀ
´
performed by the Servei de Recursos Cientıfics i Tecnics de la
Universidad Rovira i Virgili (Tarragona). Infrared spectra were
(d, 1H, JHH = 7.0, H5), 2.37 (m, 1H, JHH = 7.0, H6), 0.96 (d, 3H,
0
JHH = 6.8, H7), 0.93 (d, 3H, JHH = 7.2, H7 ). IR (cm-1):
=
ν(CdO) = 1728, ν(CdN) = 1645. MS-CI (m/z): [M þ H]þ
254.0. ee = 89%, [R]Na20 = -119.7.
ꢁ
ꢁ
ꢁ
(19) (a) Ares, R.; Lopez-Torres, M.; Fernandez, A.; Vazquez-Garcı
´
ꢁ
a,
D.; Pereira, M. T.; Vila, J. M.; Naya, L.; Fernandez, J. J. J. Organomet.
4-ClC6H3CHdNCH(CH2C6H4(40-OH))CO2Me (1d). A mix-
ture of L-tyrosine methyl ester (1.0 g, 5.20 mmol), 4-chloroben-
zaldehyde (0.731 g, 5.20 mmol), and anhydrous magnesium
sulfate (1.5 g, 12.5 mmol) was refluxed for 2 h in dichloro-
methane. After the reaction mixture was cooled to room tem-
perature, the undissolved materials were removed by filtration,
washed with dichloromethane, and discarded. The filtrate was
concentrated to dryness on a rotatory evaporator to give
compound 1d, 1.255 g (83%), as a white solid (1.619 g, 98%).
ꢁ
Chem. 2007, 692, 4197. (b) Lopez, C.; Pawelczyk, A.; Solans, X.; Font-
Bardía, M. Inorg. Chem. Commun. 2003, 6, 451. (c) Vila, J. M.; Gayoso, M.;
ꢁ
ꢁ
ꢁ
Lopez-Torres, M.; Fernandez, J. J.; Fernandez, A.; Ortigueira, J. M.; Bailey,
N. A.; Adams, H. J. Organomet. Chem. 1996, 511, 129. (d) Bosque, R.;
Granell, J.; Sales, J.; Font-Bardía, M.; Solans, X. J. Organomet. Chem.
1993, 453, 147.
(20) (a) Haddadin, M. J.; Kurth, M. J.; Olmstead, M. M. Tetrahedron
Lett. 2000, 41, 5613. (b) Huang, K. S.; Haddadin, M. J.; Olmstead, M. M.;
Kurth, M. J. J. Org. Chem. 2001, 66, 1310.

220 Organometallics, Vol. 29, No. 1, 2010
Albert et al.
1H NMR (200 MHz, CDCl3, 298 K), δ (ppm): 7.84 (s, 1H, H4),
7.62 (d, 2H, JHH = 8.4, H2), 7.36 (d, 2H, JHH = 8.4, H1), 7.00 (d,
2H, JHH = 8.4, H7), 6.68 (d, 2H, JHH = 8.4, H8), 4.10 (dd, 1H,
acetic acid for 1 h. The resulting suspension was filtered through
Celite, the filtrate was concentrated to dryness on a rotatory
evaporator, and the solid obtained was eluted through a SiO2
column, with ethyl acetate-hexane (10:4) as eluent, to obtain 2d
as a yellow solid after addition of hexane, 445 mg (69% yield).
Synthesis of 3a-d. (μ-Cl)2[Pd{K2-(C,N)-4-ClC6H3CHdNCH2-
CO2Me}]2 (3a). A mixture of imine 1a (284 mg, 1.34 mmol) and
palladium acetate (300 mg, 1.34 mmol) in 35 mL of acetone was
stirred at room temperature for 5 days. The resulting suspension was
filtered, and the filtrate was concentrated to dryness on a rotatory
evaporator to give a red solid. The red solid was dissolved in acetone
(30 mL). LiCl (2.01 mmol, 85 mg) was added to the solution, and the
mixture was stirred at room temperature for 1 h. The resulting
solution was concentrated to half volume on a rotatory evaporator,
and the yellow solid obtained was filtered and dried to obtain 3a,
334mg(71%yield).IR(KBr),ν(cm-1):ν(CdO) = 1744, ν(CdN) =
JHH = 8.8, JHH= 5.0, H5), 3.74 (s, 3H, CO2Me), 3.28 (dd, 1H,
J
HH = 13.6, JHH = 5.2, H6), 3.06 (dd, 1H, JHH = 13.6, JHH = 8.8,
0
H6 ). IR (cm-1): ν(OH) = 3356, ν(CdO) = 1722, ν(CdN) =
=
20
1648. MS-CI (m/z): [M þ H]þ = 317.9. ee > 99%, [R]Na
-270.0.
Cyclometalation Reactions. Synthesis of 2a-d, in Acetone.
(μ-OAc)2[Pd{K2-(C,N)-4-ClC6H3CHdNCH2CO2Me}]2 (2a). A
mixture of imine 1a (284 mg, 1.34 mmol) and palladium acetate
(300 mg, 1.34 mmol) in 35 mL of acetone was stirred at room
temperature for 5 days. The resulting suspension was filtered
through Celite, and the filtrate was concentrated to dryness on a
rotatory evaporator to give a red solid, after addition of diethyl
ether. The solid was washed with diethyl ether and dried to
obtain 2a, 312 mg (62% yield). IR (KBr), ν (cm-1): ν (CdO) =
1749, ν(CdN) = 1609, νa(COO-) = 1582, νs(COO-) = 1412.
MS-MALDI TOF (þ) m/z:[M- OAc]þ =693.1,[M/2- OAc]þ =
318.2. Anal. Calcd for C24H24Cl2N2O8Pd2: C 38.32, H 3.22, N 3.72.
Found: C 38.5, H 3.7, N 3.8.
1621. MS-MALDI TOF (þ) m/z: [M þ H]þ = 703.7, [M - Cl]þ
=
668.7. Anal. Calcd for C20H18Cl4N2O4Pd2: C 34.07, H 2.57, N 3.97.
Found: C 34.3, H 2.6, N 3.9.
(μ-Cl)2[Pd{K2-(C,N)-4-ClC6H3CHdNCH(Me)CO2Me}]2 (3b).
3b was obtained using the same procedure as that described above
from 302 mg (1.34 mmol) of imine 1b. Yield: 303 mg (72%). 1H
NMR (400 MHz, CDCl3, δ ppm): 8.03 (s, 1H, H4), 7.32 (br s, 1H,
H1), 7.18 (d, 1H, JHH = 7.9, H3), 7.08 (d, 1H, JHH = 7.9, H2), 4.66
(br q, 1H, J = 6.9, H5), 3.82 (s, 3H, CO2Me), 1.67 (br s, 1H, H6). IR
(KBr), ν (cm-1): ν(CdO) = 1745, ν(CdN) = 1611. MS-MALDI
TOF (þ) m/z: [M - Cl]þ = 698.9. Anal. Calcd for C22H22Cl4N2-
O4Pd2: C 36.04, H 3.02, N 3.82. Found: C 36.1, H 3.2, N 3.8.
(μ-Cl)2[Pd{K2-(C,N)-4-ClC6H3CHdNCH(iPr)CO2Me}]2 (3c).
A mixture of imine 1c (340 mg, 1.34 mmol) and palladium acetate
(300 mg, 1.34 mmol) in 35 mL of acetone was stirred at room
temperature for 5 days. The resulting suspension was filtered, and
the filtrate was concentrated to dryness on a rotatory evaporator to
give a red solid. The red solid was dissolved in acetone (30 mL).
LiCl (2.01 mmol, 85 mg) was added to the solution, and the
mixture was stirred at room temperature for 1 h. The resulting
solution was concentrated to dryness on a rotatory evaporator,
and the solid obtained was eluted through a SiO2 column, with
ethyl acetate-hexane (1:1) as eluent, to obtain 3c as a yellow solid
after addition of hexane, 328 mg (62% yield). 1H NMR (400 MHz,
CDCl3, δ in ppm): 8.34 (s, 1H, H4), 7.33 (d, 1H, JHH = 1.8, H1),
7.21 (d, 1H, JHH = 8.0, H3), 7.08 (dd, 1H, JHH = 8.0, JHH = 1.9,
H2), 4.57 (d, 1H, JHH = 8.0, H5), 3.79 (s, 3H, CO2Me), 2.38 (dh,
1H, JHH = 8.3, JHH = 6.7, H3), 1.16 (d, 3H, JHH = 6.7, H7), 1.06
(μ-OAc)2[Pd{K2-(C,N)-4-ClC6H3CHdNCH(Me)CO2Me}]2
(2b). A mixture of imine 1b (302 mg, 1.34 mmol) and palladium
acetate (300 mg, 1.34 mmol) in 35 mL of acetone was stirred at
room temperature for 5 days. The resulting suspension was filtered
through Celite, the filtrate was concentrated to dryness on a
rotatory evaporator, and the solid obtained was eluted through
a SiO2 column, with ethyl acetate-hexane (2:1) as eluent, to obtain
2b as a yellow solid after addition of diethyl ether, 336 mg (72%
yield). IR (KBr), ν(cm-1):ν(CdO) = 1744, ν(CdN) þ νa(COO-) =
1579, νs(COO-) = 1419. MS-MALDI TOF (þ) m/z: [M -
OAc]þ = 721.0. Anal. Calcd for C26H28Cl2N2O8Pd2: C 40.02, H
3.61, N 3.59. Found: C 40.0, H 3.7, N 3.6.
(μ-OAc)2[Pd{K2-(C,N)-4-ClC6H3CHdNCH(iPr)CO2Me}]2
(2c). 2c was obtained using the same procedure as that
described above for 2b, from 340 mg (1.34 mmol) of imine
1c. Yield: 224 mg (40%). IR (KBr), ν (cm-1): ν(CdO) = 1739,
ν(CdN) þ νa(COO-) = 1585, νs(COO-) = 1419. MS-MAL-
DI TOF (þ) m/z: [M - OAc]þ= 779.0, [M/2 - OAc]þ= 358.1.
Anal. Calcd for C30H36Cl2N2O8Pd2: C 43.08, H 4.34, N 3.27.
Found: C 43.3, H 4.4, N 3.3.
(μ-OAc)2[Pd{K2-(C,N)-4-ClC6H3CHdNCH(CH2C6H4(4-OH))-
CO2Me}]2 (2d). 2d was obtained using the same procedure as that
described above from 426 mg (1.34 mmol) of imine 1d. Yield: 484 mg
(75%). IR (KBr), ν (cm-1): ν(CdO) = 1740, ν(CdN) = 1609,
νa(COO-) = 1581, νs(COO-) = 1419. MS-MALDI TOF (þ) m/z:
[M - OAc - HOAc]þ = 844.8. Anal. Calcd for C38H36Cl2N2-
O10Pd2: C 47.32, H 3.76, N 2.90. Found: 47.5, H 3.9, N 2.9.
Synthesis of 2a-d, in Acetic Acid. A mixture of imine 1a
(284 mg, 1.34 mmol) and palladium acetate (300 mg, 1.34 mmol)
was stirred in 35 mL of refluxing acetic acid for 1 h. The resulting
suspension was filtered through Celite, and the filtrate was
concentrated to dryness on a vacuum line to give a red solid
after addition of diethyl ether, 352 mg (70% yield).
A mixture of imine 1b (302 mg, 1.34 mmol) and palladium
acetate (300 mg, 1.34 mmol) was stirred in 35 mL of refluxing
acetic acid for 1 h. The resulting suspension was filtered through
Celite, the filtrate was concentrated to dryness on a rotatory
evaporator, and the solid obtained was eluted through a SiO2
column, with ethyl acetate-hexane (2:1) as eluent, to obtain 2b
as a yellow solid after addition of hexane, 366 mg (70% yield).
A mixture of imine 1c (340 mg, 1.34 mmol) and palladium
acetate (300 mg, 1.34 mmol) was stirred in 35 mL of refluxing
acetic acid for 1 h. The resulting suspension was filtered through
Celite, the filtrate was concentrated to dryness on a rotatory
evaporator, and the solid obtained was eluted through a SiO2
column, with ethyl acetate-hexane (1:1) as eluent, to obtain 2c
as a yellow solid after addition of hexane, 224 mg (40% yield).
A mixture of imine 1d (4.26 mg, 1.34 mmol) and palladium
acetate (300 mg, 1.34 mmol) was stirred in 35 mL of refluxing
(d, 3H, JHH = 6.6, H7 ). IR (KBr), ν (cm-1): ν(CdO) = 1742,
0
ν(CdN) = 1602. MS-MALDI TOF (þ) m/z: [M - Cl]þ = 755.0.
Anal. Calcd for C26H30Cl4N2O4Pd2: C 39.57, H 3.83, N 3.55.
Found: C 39.8, H 3.6, N 3.5.
(μ-Cl)2[Pd{K2-(C,N)-4-ClC6H3CHdNCH(CH2C6H4(4-OH))-
CO2Me}]2 (3d). 3d was obtained using the same procedure as that
described above for 3c, from 426 mg (1.34 mmol) of imine 1d.
Yield: 436 mg (79%). 3d: 1H NMR (400 MHz, CDCl3, δ in ppm,
J inHz):7.62 (br s, 1H, H4), 7.34 (br s, 1H, H1), 7.16 (d, 3H, JHH
8.3, H2þH8), 7.04 (s, 1H, H2), 6.73 (d, 1H, JHH = 8.1, H7), 4.59 (br
s, 1H, H5), 3.77 (s, 3H, CO2Me), 3.51 (dd, 1H, JHH = 14.1, JHH
=
=
0
7.1, H6), 3.18 (dd, 1H, JHH = 14.4, JHH = 6.3, H6 ). IR (KBr),
ν (cm-1): ν(CdO) = 1734, ν(CdN) = 1608. MS-MALDI TOF
(þ) m/z:[M - Cl]þ =880.9, [M/2- Cl]þ = 424.0. Anal. Calcd for
C34H30Cl4N2O6Pd2: C 44.52, H 3.30, N 3.06. Found: C 45.0, H 3.6,
N 3.0.
Mononuclear Amine Derivatives 4, 5, and 7. Synthesis of
4a-d in CDCl3 Solution. The addition of few drops of pyr-
idine-D5 to a solution of 2 in CDCl3 affords the corresponding
mononuclear compounds 4a-d in solution. 4a: 1H NMR (200
MHz, CDCl3, 298 K), δ (ppm): 7.95 (s, 1H, H4), 7.23 (d, 1H,
J
(s, 1H, JHH = 1.9, H1), 4.37 (s, 2H, H5), 3.83 (s, 3H, CO2Me),
HH = 8.0, H3), 7.03 (dd, 1H, JHH = 8.0, JHH = 1.9, H2), 6.17
1
1.90 (s, 3H, OAc). 4b: H NMR (200 MHz, CDCl3, 298 K),
δ(ppm): 8.07 (s, 1H, H4), 7.24 (d, 1H, JHH = 8.0, H3), 7.03 (dd,
1H, JHH = 8.0, JHH = 1.9, H2), 6.11 (s, 1H, JHH = 1.9, H1), 4.64

Article
Organometallics, Vol. 29, No. 1, 2010 221
(q, 1H, JHH = 7.0, H5), 3.82 (s, 3H, CO2Me), 1.88 (s, 3H, OAc),
1.65 (d, 3H, JHH = 7.1, H6). 4c: 1H NMR (400 MHz, CDCl3,
298 K), δ (ppm): 8.39 (s, 1H, H4), 7.26 (d, JHH = 8.0, H3), 7.03
(dd, 1H, JHH = 8.0, JHH = 1.9, H2), 6.09 (s, 1H, JHH = 1.9, H1),
4.46 (d, 1H, JHH = 8.4, H5), 3.79 (s, 3H, CO2Me), 2.37 (m, 1H,
Compounds Containing PPh3, 6, 8, and 9. [Pd{K2-(C,N)-4-
ClC6H3CHdNCH2CO2Me}(OAc)(PPh3)] (6a). A mixture of 2a
(112 mg, 0.15 mmol) and triphenylphosphine (79 mg, 0.30
mmol) in 30 mL of acetone was stirred at room temperature
for 1 h. The resulting solution was concentrated to dryness on a
rotatory evaporator to give a yellow solid, after addition of
diethyl ether The yellow solid obtained was filtered, washed with
diethyl ether, and dried under vacuum to obtain 6a, 180 mg
(94% yield). 1H NMR (400 MHz, CDCl3, 298 K), δ (ppm): 8.16
(d, 1H, JPH = 7.2, H4), 7.76 (m, 6H, PPh3 ortho), 7.43 (m, 9H,
PPh3 meta and para), 7.21 (d, 1H, JHH = 8.0, H3), 6.89 (dd, 1H,
H6), 1.92 (s, 3H, OAc), 1.15 (d, 3H, JHH = 6.7, H7), 1.02 (d, 3H,
1
0
JHH= 6.6, H7 ). 4d: H NMR (400 MHz, CDCl3, 298 K), δ
(ppm): 7.66 (s, 1H, H4), 7.08 (d, 1H, JHH = 7.9, H3), 7.06 (d, 2H,
JHH = 8.3, H7), 6.97 (dd, 1H, JHH = 7.9, JHH = 1.8, H2), 6.83
(d, 2H, JHH = 8.3, H8), 6.05 (d, 1H, JHH = 1.8, H1), 4.51 (t, 1H,
JHH= 6.7, H5), 3.75 (s, 3H, CO2Me), 3.39 (dd, 1H, JHH = 14.0,
0
JHH = 7.7, H6), 3.27 (dd, 1H, JHH = 14.0, JHH = 6.2, H6 ), 1.88
(s, 3H, OAc).
Synthesis of 5b, 5c, and 5d in CDCl3 Solution. The addition of
0.9 mL (0.8 mL in the case of 2c) of a solution of (S)-(-)-R-
methylbenzylamine in CDCl3 (33 mg, 0.27 mmol, in 5 mL of
CDCl3) to 0.028 mmol of 2 in CDCl3 affords the corresponding
mononuclear compounds 5b-d in solution. 1H NMR (400
MHz, CDCl3, 298 K), (S,S)-5b δ (ppm): 7.99 (s, 1H, H4), 7.46
(d, 2H, JHH =8.2, Hamine-ortho), 7.38 (t, 2H, JHH = 7.5, Hamine-meta),
7.31 (t, 1H, JHH = 7.5, Hamine-para), 7.24 (d, 1H, JHH = 8.2, H3),
7.07 (dd, 1H, JHH = 8.0, JHH = 1.9, H2), 6.78 (d, 1H,
J
HH = 8.0, JHH = 1.9, H2), 6.33 (dd, 1H, JPH = 5.3, JHH = 1.9,
H1), 4.43 (d, 2H, JPH = 3.5, H5), 3.77 (s, 3H, CO2Me), 1.38 (s,
3H, OAc). 31P{1H} NMR (121.4 MHz, CH2Cl2, 298 K), δ
(ppm): 39.40 (s). IR (KBr), ν (cm-1): ν(CdO) = 1754,
ν(CdN) = 1571, νa(COO-) = 1618, νs(COO-) = 1374, PPh3
(q-X sensitive) = 1098. EM-ESI (m/z): [M - OAc]þ = 580.0.
Anal. Calcd for C30H27ClNO4PPd: C 56.44, H 4.26, N 2.19.
Found: C 56.6, H 4.4, N 2.2.
[Pd{K2-(C,N)-4-ClC6H3CHdNCH(Me)CO2Me}(OAc)(PPh3)]
(6b). A mixture of 2b (190 mg, 0.24 mmol) and triphenylphosphine
(128 mg, 0.48 mmol) in 30 mL of acetone was stirred at room
temperature for 1 h. The resulting solution was filtered through
Celite, and the filtrate was concentrated to dryness on a rotatory
evaporator to give a yellow solid after addition of diethyl ether. The
yellow solid obtained was filtered, washed with diethyl ether, and
dried under vacuum to obtain 6b, 291 mg (93% yield). 1H NMR
(400 MHz, CDCl3, 298 K), δ (ppm): 8.29 (d, 1H, JPH = 7.4, H4),
7.72-7.80 (m, 6H, PPh3 ortho), 7.35-7.50 (m, 9H, PPh3 meta and
J
HH = 1.8, H1), 4.50 (q, 1H, JHH = 7.2, H5), 4.15 (m, 1H, Hamine),
3.78 (s, 3H, CO2Me), 3.45 (d, 1H, JHH = 9.4, NH2), 1.94 (s, 3H,
OAc), 1.81 (d, 3H, JHH = 6.8, Hamine-methyl), 1.64 (d, 3H, JHH
7.0, H6). 1H NMR (400 MHz, CDCl3, 298 K), (R,S)-5b, selected
signals, δ (ppm): 8.00 (s, 1H, H4), 7.06 (dd, 1H, JHH = 8.0, JHH
=
=
1.9, H2), 6.76 (s, 1H, JHH = 1.8, H1), 4.54 (q, 1H, JHH = 7.5, H5),
3.77 (s, 3H, CO2Me), 3.60 (d, 1H, JHH = 9.4, NH2), 1.66 (d, 3H,
JHH =7.2, Hamine-methyl). NMR (400 MHz, CDCl3, 298 K), (S,S)-
5c, δ (ppm): 8.34 (s, 1H, H4), 7.45 (d, 2H, JHH = 7.2, Hamine-ortho),
7.38 (t, 2H, JHH = 7.5, Hamine-meta), 7.31 (t, 1H, JHH = 7.6,
para), 7.22 (d, 1H, JHH = 8.0, H3), 6.88 (dd, 1H, JHH = 8.0, JHH
=
1.8, H2), 6.33 (dd, 1H, JPH = 5.4, JHH = 1.8, H1), 4.77 (qd, 1H,
JHH = 7.0, JPH = 3.4, H5), 3.75 (s, 3H, CO2Me), 1.61 (d, 3H,
JHH = 7.1, H6), 1.42 (s, 3H, OAc). 31P{1H} NMR (121.4 MHz,
CH2Cl2, 298 K), δ(ppm):39.11(s). IR(KBr), ν(cm-1):ν(CdO) =
1742, ν(CdN) = 1562, νa(COO-) = 1616, νs(COO-) = 1366,
H
amine-para), 7.25 (m, H3 þ CHCl3), 7.07 (dd, 1H, JHH =8.0, JHH
=
1.7, H2), 6.76 (d, 1H, JHH = 1.7, H1), 4.66 (d, 1H, JHH = 8.2, H5),
4.17 (m, 1H, Hamine), 3.77 (s, 3H, CO2Me), 3.58 (d, 1H, JHH = 8.9,
NH2), 2.37 (m, 3H, JHH = 7.0, H6), 2.03 (s, 3H, OAc), 1.81 (d, 3H,
JHH = 6.8, Hamine-methyl), 1.13 (d, 3H, JHH = 6.7, H7), 1.07 (d, 3H,
JHH = 6.6, H7). 1H NMR (400 MHz, CDCl3, 298 K), (R,S)-5c,
selected signals, δ (ppm): 8.36 (s, 1H, H4), 7.08 (d, 1H, JHH = 8.0,
H2), 6.73 (s, 1H, JHH = 1.7, H1), 4.69 (d, 1H, JHH = 8.1, H5) 3.76
(s, 3H, CO2Me), 3.68 (d, 1H, JHH = 9.2, NH2), 2.36 (m, 1H, H6),
PPh3 (q-X sensitive) = 1096. EM-MALDI (m/z): [M - OAc]þ
=
594.1. Anal. Calcd for C31H29ClNO4PPd: C 57.07, H 4.48, N 2.15.
Found: C 57.7, H 4.2, N 2.1.
[Pd{K2-(C,N)-4-ClC6H3CHdNCH(iPr)CO2Me}(OAc)(PPh3)]
(6c). 6c was obtained using the same procedure as that described
above from 125 mg (0.15 mmol) of cyclometalated derivative 2c.
1
Yield: 132 mg (65%). H NMR (400 MHz, CDCl3, 298 K), δ
2.03 (s, 3H, OAc), 1.81 (d, 3H, JHH = 6.7, Hamine-methyl), 1.08 (d,
0
(ppm): 8.56 (d, 1H, JPH = 7.72, H4), 7.72-7.80 (m, 6H, PPh3,
1
3H, JHH = 6.6, H7), 1.02 (d, 3H, JHH = 6.7, H7 ). H NMR (400
ortho), 7.35-7.50 (m, 9H, PPh3, meta and para), 7.24 (d, 1H,
MHz, CDCl3, 298 K), (S,S)-5d, δ (ppm): 7.5-6.6 (m, 13H, H4 þ
JHH = 8.0, H3), 6.88 (dd, 1H, JHH = 8.0, JHH = 1.9, H2), 6.31 (dd,
1H, JPH = 5.5, JHH = 1.9, H1), 4.55 (dd, 1H, JHH = 8.3, JPH
Har), 3.77 (s, 3H, CO2Me), 3.58 (d, 1H, JHH = 8.9, NH2), 3.56 (d,
=
3.1, H5), 3.74 (s, 3H, CO2Me), 2.38 (m, 1H, JHH = 8.0, JHH = 6.7,
H6), 1.35 (s, 3H, OAc), 1.11 (d, 3H, JHH = 6.7, H7), 0.99 (d, 3H,
0
1H, JHH = 14.9, H6), 3.34 (dd, 1H, JHH = 14.3, JHH = 4.0, H6 ),
1.96 (s, 3H, OAc), 1.77 (d, 3H, JHH = 6.7, Hamine-methyl). 1H NMR
(400 MHz, CDCl3, 298 K), (R,S)-5d, selected signals, δ (ppm): 3.71
(s, 3H, CO2Me), 3.39 (dd, 1H, JHH = 14.3, JHH = 4.0, H6), 3.22
0
J
HH = 6.6, H7 ). 31P{1H} NMR (121.4 MHz, CH2Cl2, 298 K), δ
(ppm): 39.25 (s). IR(KBr), ν (cm-1): ν(CdO) = 1736, ν(CdN) =
1570, νa(COO-) = 1612, νs(COO-) = 1372, PPh3 (q-Xsensitive) =
1097. EM-MALDI (m/z): [M - OAc]þ = 620.1. Anal. Calcd for
C33H33ClNO4PPd: C 58.25, H 4.89, N 2.06. Found: C 58.6, H 4.9,
N 2.0.
0
(dd, 1H, JHH = 14.2, JHH = 9.5, H6 ).
Synthesis of 7a-d in CDCl3 Solution. The addition of a few
drops of pyridine-D5 to a solution of 3 in CDCl3 affords the
corresponding mononuclear compound 7a-d in solution. 7a,
1H NMR (400 MHz, CDCl3, 298 K), δ (ppm): 7.98 (s, 1H, H4),
7.26 (d, 1H, JHH = 8.0, H3), 7.07 (dd, 1H, JHH = 8.0, JHH = 2.0,
H2), 6.14 (s, 1H, H1), 4.72 (s, 2H, H5), 3.81 (s, 3H, CO2Me). 7b,
1H NMR (400 MHz, CDCl3, 298 K), δ (ppm): 8.16 (s, 1H, H4),
7.27 (d, 1H, JHH = 8.0, H3), 7.07 (d, 1H, JHH = 8.0, H2), 6.09 (s,
1H, H1), 5.47 (q, 1H, JHH = 6.8, H5), 3.80 (s, 3H, CO2Me), 1.67
(d, 3H, JHH = 7.2, H6). 7c, 1H NMR (400 MHz, CDCl3, 298 K),
δ (ppm): 8.46 (s, 1H, H4), 7.30 (d, 1H, JHH = 8.0, H3), 7.07 (dd,
1H, JHH = 8.0, JHH = 2.0, H2), 6.06 (s, 1H, H1), 5.47 (d, 1H,
[Pd{K2-(C,N)-4-ClC6H3CHdNCH(CH2C6H4(4-OH))CO2Me}-
(OAc)(PPh3)] (6d). 6d was obtained using the same procedure as
that described above from 144 mg (0.15 mmol) of cyclometalated
derivative 6d. Yield: 194 mg (87%). 1H NMR (400 MHz, CDCl3,
298 K), δ(ppm):7.76 (m, 7H, H4 þ PPh3 ortho), 7.34 (m, 9H, PPh3
meta and para), 7.03 (m, 3H, H3, H7), 6.84 (m, 3H, H2, H8), 6.33
(dd, 1H, JHP = 6.5, JHH = 1.8, H1), 4.60 (m, 1H, H5), 3.68 (s, 3H,
CO2Me), 3.28 (dd, 1H, JHH = 14.0, JHH = 7.5, H6), 3.21 (dd, 1H,
0
J
HH = 14.0, JHH = 6.5, H6 ), 1.30 (br s, 3H, OAc). 31P{1H} NMR
JHH = 8.4, H5), 3.77 (s, 3H, CO2Me), 2.37 (m, 1H, JHH = 7.8,
JHH = 6.7, H6), 1.08 (d, 3H, JHH = 6.8, H7), 1.07 (d, 3H, JHH
(121.4 MHz, CH2Cl2, 298 K), δ (ppm): 39.50 (s). IR (KBr), ν
(cm-1): ν(CdO) = 1741, υ(CdN) = 1573, νa(COO-) = 1615,
νs(COO-) = 1402, PPh3 (q-X sensitive) = 1097. EM-MALDI (m/
z): [M - OAc]þ = 686.0. Anal. Calcd for C37H33ClNO5PPd: C
59.69, H 4.47, N 1.88. Found: C 59.8, H 4.5, N 1.9.
=
1
0
6.4, H7 ). 7d, HNMR(400MHz, CDCl3, 298K), δ(ppm):7.76(s,
1H, H4), 7.10 (m, 3H, H3þH7), 7.01 (dd, 1H, JHH = 8.0, JHH =
1.8, H2), 6.75 (d, 2H, JHH = 8.4, H8), 6.03 (d, 1H, JHH = 1.7, H1),
5.47 (br, 1H, H5), 3.72 (s, 3H, CO2Me), 3.56 (dd, 1H, JHH = 13.9,
[Pd{K2-(C,N)-4-ClC6H3CHdNCH2CO2Me}Cl(PPh3)] (8a).
A mixture of 3a (112 mg, 0.15 mmol) and triphenylphosphine
0
JHH = 6.0, H6), 3.23 (dd, 1H, JHH = 14.0, JHH = 6.9, H6 ).

222 Organometallics, Vol. 29, No. 1, 2010
Albert et al.
(79 mg, 0.30 mmol) in 30 mL of acetone was stirred at room
temperature for 2 h. The resulting solution was filtered through
Celite and concentrated to dryness on a rotatory evaporator to
give a yellow solid after addition of diethyl ether. The yellow
solid obtained was filtered, washed with diethyl ether, and dried
under vacuum to obtain 8a, 151 mg (82% yield). 1H NMR (400
MHz, CDCl3, 298 K), δ (ppm): 8.18 (d, 1H, JPH =7.6, H4),
7.66-7.75 (m, 6H, PPh3 ortho), 7.34-7.50 (m, 9H, PPh3 meta
and para), 7.24 (d, 1H, JHH= 8.0, H3), 6.91 (dd, 1H, JHH = 8.0,
recrystallized from dichlorometane-methanol to obtain 9c, 40
mg (83% yield). 1H NMR (300 MHz, CDCl3, 298 K), δ (ppm):
8.03 (dd, 1H, JPH = 10.0, JHH = 1.1, H4), 7.60-7.80 (m, 6H,
PPh3 ortho), 7.48-7.51 (m, 6H, PPh3 meta), 7.37-7.46 (m, 1H,
PPh3 para), 7.21 (d, 1H, JHH = 8.2, H3), 6.96 (dd, 1H, JHH
=
8.0, JHH = 2.0, H2), 5.99 (dd, 1H, JPH = 3.7, JHH = 2.0, H1),
4.21 (ddd, 1H, JPH = 4.7, JHH = 4.0, JHH = 1.1, H5), 2.38 (hd,
1H, JHH = 6.9, JHH = 3.7, H6), 1.21 (d, 3H, JHH = 6.9, H7),
1.19 (d, 3H, JHH = 6.9, H7 ). 31P{1H} NMR (121.4 MHz,
0
J
HH = 1.6, H2), 6.25 (dd, 1H, JPH = 6.0, JHH = 1.6, H1), 4.83
CH2Cl2, 298 K), δ (ppm): 32.93(s). EM-ESI (m/z): 606.05 ((M
þ H)þ. Anal. Calcd for C30H27ClNO2PPd: C 59.42, H 4.49, N
2.31. Found: C 59.3, H 4.4, N 2.3.
(d, 2H, JPH = 3.2, H5), 3.77 (s, 3H, CO2Me). 31P{1H} NMR
(121.4 MHz, CH2Cl2, 298 K), δ (ppm): 40.48 (s). IR (KBr),
ν
(cm-1): ν(CdO) = 1737, ν(CdN) = 1629, PPh3 (q-X
[Pd{K3-(C,N,O)-4-ClC6H3CHdNCH(CH2C6H4(4-OH))CO2}-
(PPh3)] (9d). 9d was obtained by refluxing an acetone solution
(20 mL) of 6d (102 mg, 0.15 mmol) for 24 h. The resulting solution
was concentrated to dryness on a rotatory evaporator to give a
yellow solid after addition of diethyl ether. The yellow solid
obtained was filtered and recrystallized from dichlorometa-
ne-diethyl ether to obtain 9d, 70 mg (70% yield). 1H NMR (400
MHz, CDCl3, 298 K), δ (ppm): 7.64-7.73 (m, 7H, H4 þ PPh3
ortho), 7.48-7.51 (m, 6H, PPh3 meta), 7.38-7.49 (m, 3H, PPh3
para), 6.95 (m, 3H, H3, H7), 6.75 (m, 3H, H2, H8), 5.98 (dd, 1H,
sensitive)=1097. EM-MALDI (m/z): [M - Cl]þ=579.8, [M-Cl
- Pd]þ = 471.9. Anal. Calcd for C28H24Cl2NO2PPd: C 54.70,
H 3.93, N 2.28. Found: C 54.9, H 4.2, N 2.2.
[Pd{K2-(C,N)-4-ClC6H3CHdNCH(Me)CO2Me}Cl(PPh3)] (8b).
A mixture of 3b (109 mg, 0.15 mmol) and triphenylphosphine (79
mg, 0.30 mmol) in 30 mL of acetone was stirred at room temperature
for 2 h. The resulting solution was filtered through Celite and
concentrated to dryness on a rotatory evaporator, and the solid
obtained was eluted through a SiO2 column, with ethyl chloro-
form-acetone (100:4) as eluent, to obtain 8b as a yellow solid after
addition of diethyl ether, 102 mg (54% yield). 1H NMR (400 MHz,
CDCl3, 298 K), δ (ppm): 8.36 (s, 1H, H4), 7.68-7.77 (m, 6H, PPh3
J
HP = 3.8, JHH = 1.9, H1), 4.46 (m, 1H, H5), 3.10 (m, 2H, H6).
31P{1H} NMR (121.4 MHz, CH2Cl2, 298 K), δ (ppm): 32.22 (s).
EM-MALDI (m/z): 670.05 (M þ H)þ. Anal. Calcd for
C34H27ClNO3PPd: C 60.91, H 4.06, N 2.09. Found: C 60.7, H
3.8, N 2.1.
ortho), 7.35-7.50 (m, 9H, PPh3 meta and para), 7.25 (d, 1H, JHH
=
8.0, H3), 6.91 (dd, 1H, JHH = 8.0, JHH = 2.0, H2), 6.25 (dd, 1H,
JPH =6.0, JHH =1.6, H1), 5.71(dq, 1H, JHH =7.2, JPH =3.2, H5),
3.76 (s, 3H, CO2Me), 1.64 (d, 3H, JHH = 7.2, H6). 31P{1H} NMR
(121.4 MHz, CH2Cl2,298K),δ(ppm):40.64(s).IR(KBr),ν(cm-1):
ν(CdO) = 1719, ν(CdN) = 1621, PPh3 (q-X sensitive) = 1101.
EM-MALDI (m/z): M - Cl]þ = 594.0, [M - Cl - Pd]þ = 486.2.
Anal. Calcd for C29H26Cl2NO2PPd C 55.39, H 4.17, N 2.23. Found:
C 55.3, H 4.4, N 2.2.
NMR Data of Compounds 10a-d. 10a, 1H NMR (400 MHz,
acetone-D6, 298 K), δ (ppm): 8.36 (s, 1H, H4), 7.54 (d, 1H,
J
HH = 8.1, H3), 7.27 (dd, 1H, JHH = 8.0, JHH = 1.73, H2), 6.71
(br s, 1H, H1), 4.46 (s, 2H, H5), 3.78 (s, 3H, CO2Me), 3.69 (br s,
H2O). 19F NMR (376.5 MHz, acetone-D6), δ (ppm): -151.89
(br s, F-11B, 80.9%), -151.84 (br s, F-10B, 19.1%).
10b: 1H NMR (400 MHz, acetone-D6, 298 K), δ (ppm): 8.42
(s, 1H, H4), 7.51 (d, 1H, JHH = 7.9, H3), 7.23 (d, 1H, JHH = 7.9,
H2), 6.90 (br s, 1H, H1), 4.60 (m, 1H, H5), 3.79 (s, 3H, CO2Me),
3.34 (br s, H2O), 1.70 (d, 3H, JHH = 7.0, H6). 19F NMR (376.5
MHz, acetone-D6), δ (ppm): -152.22 (br s, F-11B, 80.9%),
-152.17 (br s, F-10B, 19.1%).
[Pd{K2-(C,N)-4-ClC6H3CHdNCH(iPr)CO2Me}Cl(PPh3)] (8c).
8c was obtained using the same procedure as that described above
for the synthesis of 8a, from 118 mg (0.15 mmol) of cyclometalated
derivative 3c. Yield: 142 mg (72%). 1H NMR (400 MHz, CDCl3,298
K), δ (ppm): 8.68 (d, 1H, JPH = 8.0, H4), 7.68-7.77 (m, 6H, PPh3
10c: 1H NMR (400 MHz, acetone-D6, 298 K), δ (ppm): 8.52
(s, 1H, H4), 7.56 (d, 1H, JHH = 8.0, H3), 7.26 (d, 1H, JHH = 7.6,
H2), 6.84 (br s, 1H, H1), 4.06 (br s, 1H, H5), 3.82 (s, 3H, CO2Me),
ortho), 7.35-7.50 (m, 9H, PPh3 meta and para), 7.28 (d, 1H, JHH
8.0, H3), 6.91 (dd, 1H, JHH = 8.0, JHH = 2.0, H2), 6.25 (dd, 1H,
PH =6.4, JHH =2.0, H1), 5.67(dd, 1H, JHH =8.0, JPH =3.2, H5),
=
J
0
3.33 (br s, H2O), 2.47 (dh, 1H, JHH = 8.6, JHH = 6.8, H6), 1.14
0
3.74 (s, 3H, CO2Me), 2.37 (dh, 1H, JHH = 7.9, JHH = 6.6, H6), 1.11
(d, 3H, JHH = 6.6, H7), 1.05 (d, 3H, JHH = 6.6, H7 ). 19F NMR
(d, 3H, JHH =6.8, H7), 1.04 (d, 3H, JHH =6.8, H7 ). 31P{1H} NMR
0
(376.5 MHz, acetone-D6), δ (ppm): -152.79 (br s, F-11B,
(121.4 MHz, CH2Cl2,298K),δ(ppm):41.15(s).IR(KBr),ν(cm-1):
ν(CdO) = 1723, ν(CdN) = 1615, PPh3 (q-X sensitive) = 1097.
EM-MALDI (m/z): [M - Cl]þ = 620.4. Anal. Calcd for
C31H30Cl2NO2PPd: C 56.68, H 4.60, N 2.13. Found: C 56.8, H
4.6, N 2.1.
80.9%), -152.74 (br s, F-10B, 19.1%).
10d: 1H NMR (400 MHz, acetone-D6, 298 K), δ (ppm): 8.29
(s, 1H, OH), 8.03 (s, 1H, H4), 7.40 (d, 1H, JHH = 8.0, H3),
7.25 (d, 2H, JHH = 8.5, H7), 7.21 (d, 1H, JHH = 7.9, H2), 6.77 (d,
[Pd{K2-(C,N)-4-ClC6H3CHdNCH(CH2C6H4(4-OH))CO2Me}-
Cl(PPh3)] (8d). 8d was obtained using the same procedure as that
described above for the synthesis of 8b, from 138 mg (0.15 mmol)
0
2H, JHH = 8.5, H8), 6.69 (br s, 1H, H1), 4.55 (dd, 1H, JHH
9.9, JHH = 4.3, H5), 3.82 (s, 3H, CO2Me), 3.41 (dd, 1H, JHH
=
=
0
0
14.1, JHH = 4.4, H6), 3.19 (dd, 1H, JHH = 14.3, JHH = 10.0,
0
H6 ), 3.06 (br s, H2O). 19F NMR (376.5 MHz, acetone-D6), δ
1
of cyclometalated derivative 3d. Yield: 52 mg (24%). H NMR
(ppm): -153.18 (br s, F-11B, 80.9%), -153.12 (br s, F-10B,
19.1%).
(400 MHz, CDCl3, 298 K), δ (ppm): 8.11 (d, 1H, JPH = 1.6, H4),
7.65-7.80 (m, 6H, PPh3 ortho), 7.35-7.50 (m, 9H, PPh3 meta and
para), 7.12 (d, 2H, JHH =8.4, H7), 7.11 (d, 1H, JHH = 8.0, H3), 6.86
(dd, 1H, JHH = 8.0, JHH = 2.0, H2), 6.70 (d, 2H, JHH = 8.4, H8),
6.25 (dd, 1H, JPH =6.0,JHH =2.0,H1),5.75(m,1H,H5),5.43(brs,
[Pd{K2-(C,N)-4-ClC6H3CHdNCH2CO2Me}(dppe)]BF4 (11a).
A mixture of cyclopalladated compound 3a (50 mg, 0.07 mmol)
and silver tetrafluoroborate (41 mg, 0.21 mmol) was stirred for 1 h
in acetone at room temperature. Then the undissolved materials
were removed by filtration, washed with acetone, and discarded.
1,2-Bis(diphenylphosphino)ethane (53 mg, 0.13 mmol) was added
to the filtrate, and the mixture was stirred for 2 h in acetone at room
temperature. The resulting solution was concentrated to dryness
on a rotatory evaporator to give compound 11a after addition of
1H, OH), 3.65 (s, 3H, CO2Me), 3.55 (dd, 1H, JHH = 13.6, JHH
=
5.4, H6), 3.11 (dd, 1H, JHH = 13.6, JHH = 8.0, H6 ). 31P{1H} NMR
(121.4 MHz, CH2Cl2, 298 K), δ (ppm): 41.15 (s). IR (KBr), ν
(cm-1): ν(CdO) = 1736, ν(CdN) = 1614, PPh3 (q-X sensitive) =
0
1096. EM-MALDI (m/z): [M - Cl]þ = 686.0, [M - Cl - Pd]þ
=
578.1. Anal. Calcd for C35H30Cl2NO3PPd: C 58.31, H 4.19, N 1.94.
Found: C 58.5, H 4.3, N 1.9.
1
diethyl ether, 95 mg (90%), as a red solid. H NMR (400 MHz,
[Pd{K3-(C,N,O)-4-ClC6H3CHdNCH(iPr)CO2}(PPh3)] (9c).
9c was obtained by refluxing 20 mL of an acetone solution of
6c (54 mg, 0.09 mmol) for 24 h. The resulting solution was
concentrated to dryness on a rotatory evaporator to give
a yellow solid. The yellow solid obtained was filtered and
CDCl3, 298 K), δ (ppm): 8.64 (d, 1H, JPH = 7.4, H4), 7.4-8.1 (m,
21H, 2PPh2þH3), 7.17 (dd, 1H, JHH = 8.0, JHH = 2.0, H2), 6.62
(ddd, 1H, JPH = 7.8, JPH = 5.1, JHH = 2.0, H1), 4.26 (dd, 1H,
J
PH = 3.4, JPH = 1.5, H5), 3.35 (s, 3H, CO2Me), 2.5-2.9 (m, 4H,
2CH2). 19F NMR (376.5 MHz, CDCl3), δ (ppm): -151.96 (br s,

Article
Organometallics, Vol. 29, No. 1, 2010 223
F-11B, 80.9%), -151.91 (br s, F-10B, 19.1%). 31P{1H} NMR
(121.4 MHz, acetone-D6) δ: 62.40 (d, JPP = 25.8, PtranstoN), 45.64
(d, JPP = 25.8, P PtranstoC). IR (KBr), ν (cm-1): ν(CdO) = 1742,
ν(CdN) = 1625, ν(BF4) = 1071. MS-ESI, m/z: [M]þ = 714.07.
Anal. Calcd for C36H33BClF4NO2P2Pd: C 53.90, H 4.15, N 1.75.
Found: C 53.3, H 4.0, N 1.7.
1H, JHH = 7.2, H5), 3.75 (s, 3H, CO2Me), 2.14 (d, 3H, JHH
7.2, H6). 19F NMR (376.5 MHz, CDCl3), δ (ppm): -151.77 (br s,
F-11B, 80.9%), -151.72 (br s, F-10B, 19.1%). IR (KBr), ν
(cm-1): ν(CdO) = 1748, ν(CdN) = 1619, ν(BF4) = 1077. MS-
ESI, m/z: [M]þ = 402.5. Anal. Calcd for C25H21BClF4NO2: C
61.32, H 4.32, N 2.86. Found: C 61.8, H 4.4, N 2.9.
=
[2-CH(iPr)CO2Me-3,4-Ph2-6-Cl-C9H4N]BF4 (12c). 12c was
obtained using the same procedure as that described above from
166 mg (0.21 mmol) of cyclopalladated compound 3c, 126 mg
(0.65 mmol) of silver tetrafluoroborate, and 136 mg (0.76 mmol)
of diphenylacetylene. Yield: 165 mg (64%). 1H NMR (400 MHz,
[Pd{K2-(C,N)-4-ClC6H3CHdNCH(Me)CO2Me}(dppe)]BF4.
(11b). 11b was obtained using the same procedure as that
described above from 37 mg (0.05 mmol) of cyclopalladated
complex 3b, 30 mg (0.15 mmol) of silver tetrafluoroborate, and
40 mg (0.1 mmol) of 1,2-bis(diphenylphosphino)ethane. Yield:
74 mg (91%). 1H NMR (400 MHz, CDCl3, 298 K), δ (ppm): 8.49
(br s, 1H, H4), 7.3-8.0 (m, 21H, 2PPh2þH3), 7.05 (br s, 1H, H2),
6.53 (br s, 1H, H1), 4.13 (br s, 1H, H5), 3.49 (br s, 3H, CO2Me),
2.3-3.0 (m, 4H, 2CH2), 1.14 (d, 3H, JHH = 6.1, H6). 19F NMR
(376.5 MHz, CDCl3), δ (ppm): -152.66 (br s, F-11B, 80.9%),
-152.61 (br s, F-10B, 19.1%). 31P{1H} NMR (121.4 MHz,
CDCl3, 298 K), δ (ppm): 10.22 (s, 1H, H4), 7.90 (d, 1H, JHH
8.9, H3), 7.94 (d, 1H, JHH = 8.9, JHH = 1.9, H2), 7.58 (d, 1H,
JHH = 1.9, H1), 7.50-7.00 (m, 10H, 2Ph), 4.86 (d, 1H, JHH
10.1, H5), 3.87 (s, 3H, CO2Me), 3.08 (dh, 1H, JHH = 10.1,
=
=
J
HH = 6.5, H6), 1.08 (d, 3H, JHH = 6.5, H7), 0.88 (d, 3H, JHH =
6.6, H7 ). 19F NMR (376.5 MHz, CDCl3), δ (ppm): -152.95 (br
s, F-11B, 80.9%), -152.89 (br s, F-10B, 19.1%). IR (KBr), ν
(cm-1): ν(CdO) = 1738, ν(CdN) = 1619, ν(BF4) = 1079. MS-
ESI, m/z: [M]þ = 431.2. Anal. Calcd for C27H25BClF4NO2: C
62.63, H 4.87, N 2.87. Found: C 62.2, H 4.6, N 2.9.
0
acetone-D6) δ: 62.34 (d, JPP = 26.2, PtranstoN), 46.95 (d, JPP
=
26.2, P PtranstoC). IR (KBr), ν (cm-1): ν(CdO) = 1739, ν(CdN) =
1611, ν(BF4) = 1077. MS-MALDI, m/z: [M - CO2Me]þ = 671.3.
Anal. Calcd for C37H35BClF4NO2P2Pd: C 54.44, H 4.32, N 1.72.
Found: C 54.1, H 4.1, N 1.7.
[2-CH(CH2C6H4(4-OH)CO2Me-3,4-Ph2-6-Cl-C9H4N]BF4 (12d).
12d was obtained using the same procedure as that described above
from 238 mg (0.26 mmol) of cyclopalladated compound 3d, 152 mg
(0.78 mmol) of silver tetrafluoroborate, and 164 mg (0.92 mmol) of
diphenylacetylene. Yield: 95 mg (28%). 1H NMR (400 MHz,
[Pd{K2-(C,N)-4-ClC6H3CHdNCH(Me)CO2Me}(dppe)]BF4.
(11c). 11c was obtained using the same procedure as that
described above from 32 mg (0.04 mmol) of cyclopalladated
complex 3c, 23 mg (0.12 mmol) of silver tetrafluoroborate, and
31 mg (0.08 mmol) of 1,2-bis(diphenylphosphino)ethane. Yield:
57 mg (86%). 1H NMR (400 MHz, CDCl3, 298 K), δ (ppm): 8.65
(d, 1H, JPH = 7.5, H4), 7.4-8.1 (m, 21H, 2PPh2þH3), 7.06 (dd,
CDCl3, 298 K), δ (ppm): 10.51 (s, 1H, H4), 8.90 (d, 1H, JHH
8.9, H3), 8.21 (dd, 1H, JHH = 8.9, JHH = 1.9, H2), 7.64 (d, 1H,
HH = 1.9, H1), 7.30-7.00 (m, 9H, 9Ph), 6.88 (d, 2H, JHH = 8.5,
H7), 6.72 (d, 2H, JHH = 8.5, H8), 6.63 (dd, 1H, JHH = 7.8, JHH
1.1, 1Ph), 5.67 (dd, 1H, JHH = 8.4, JHH= 6.9, H5), 3.82 (s, 3H,
=
J
=
1H, JHH = 8.0, JHH = 1.9, H2), 6.53 (ddd, 1H, JPH = 8.0, JPH
=
5.3, JHH = 1.9, H1), 3.73 (dd, 1H, JHH = 9.9, JPH = 2.1, H5),
3.47 (s, 3H, CO2Me), 2.7-3.2 (m, 4H, 2CH2), 2.02 (dh, 1H,
0
CO2Me), 3.78 (d, 1H, JHH = 6.8, H6), 3.78 (d, 1H, JHH = 8.5, H6 ).
19F NMR (376.5 MHz, CDCl3), δ (ppm): -152.05 (br s, F-11B,
80.9%), -152.99 (br s, F-10B, 19.1%). IR (KBr), ν (cm-1):
ν(OH) = 3447, ν(CdO) = 1748, ν(CdN) = 1621, ν(BF4) =
1084. MS-ESI, m/z: [M]þ = 494.5. Anal. Calcd for C31H25-
BClF4NO3: C 64.00, H 4.33, N 2.41. Found: C 63.6, H 4.1, N 2.3.
X-ray Structure Analysis. 3c. A prismatic crystal (0.1 ꢀ 0.1 ꢀ
0.2 mm) was selected and mounted on a BrukerAXS ApexII-
CCD area detector. Unit-cell parameters were determined from
1908 reflections (2.58° < θ < 26.78°) and refined by the least-
squares method. Intensities were collected with graphite-
monochromatized Mo KR radiation; 12 370 reflections were
measured in the range 1.23° e θ e 26.37°; 10 400 reflections were
assumed as observed applying the condition I > 2σ(I). Lorentz-
polarization and absorption corrections were made. The structure
was solved by direct methods, using SIR9721 and refined by the
full-matrix least-squares method with the SHELX97 computer
JHH = 10.0, JHH = 6.6, H6), 0.48 (d, 3H, JHH = 6.5, H7), 0.41
(d, 3H, J6 = 6.6, HHH). 19F NMR (376.5 MHz, CDCl3), δ
(ppm): -156.09 (br s, F-11B, 80.0%), -152.04 (br s, F-10B,
20.0%). 31P{1H} NMR (121.4 MHz, acetone-D6) δ: 62.28 (d,
JPP = 25.7, P2), 46.12 (d, JPP = 25.6, P1). IR (cm-1): ν(CdO) =
1735, ν(CdN) = 1609, ν(BF4) = 1082. EM-MALDI (m/z): [M
- OMe]þ = 729.8. Anal. Calcd for C39H39BClF4NO2P2Pd: C
55.48, H 4.66, N 1.66. Found: C 55.8, H 4.4, N 1.6.
[2-CH2CO2Me-3,4-Ph2-6-Cl-C9H4N]BF4 (12a). A mixture of
cyclopalladated compound 3a (126 mg, 0.18 mmol) and silver
tetrafluoroborate (105 mg, 0.54 mmol) was stirred for 1 h in
acetone at room temperature. Then, the undissolved materials
were removed by filtration, washed with acetone, and discarded.
The resulting solution was concentrated to dryness on a rotatory
evaporator, and the solid obtained was dissolved in 35 mL of
nitromethane. Diphenylacetylene (112 mg, 0.63 mmol) was
added to this solution, and the mixture was refluxed for 48 h.
The resulting suspension was filtered through Celite, the filtrate
was concentrated to dryness on a rotatory evaporator, and the
solid obtained was eluted through a SiO2 column, with ethyl
acetone-chloroform (1:1) as eluent, to obtain 12a as a white
solid, 72 mg (42% yield). 1H NMR (400 MHz, CDCl3, 298 K), δ
(ppm): 10.24 (s, 1H, H4), 8.78 (d, 1H, JHH = 8.8, H3), 8.19 (d,
1H, JHH = 8.8, JHH = 2.0, H2), 7.71 (dd, 1H, JHH = 1.9, H1),
7.45 (br s, 5H, Ph), 7.40 (br s, 5H, Ph), 5.57 (s, 2H, H5), 3.70 (s,
3H, CO2Me). 19F NMR (376.5 MHz, CDCl3), δ (ppm): -154.59
(br s, F-11B, 80.9%), -154.03 (br s, F-10B, 19.1%). IR (KBr), ν
(cm-1): ν(CdO) = 1742, ν(CdN) = 1629, ν(BF4) = 1082. MS-
ESI, m/z: [M]þ = 388.5. Anal. Calcd for C24H19BClF4NO2: C
60.60, H 4.03, N 2.94. Found: C 61.1, H 3.8, N 2.9.
program,22 using 12 370 reflections; very negative intensities were
P
not assumed. The function minimized was w||Fo|2 - |Fc|2|2,
where w = [σ2(I ) þ 71.9906P]-1, and P = (|Fo|2 þ 2|Fc|2)/3. f, f 0,
and f 0 were taken from International Tables of X-ray Crystal-
lography.23 All H atoms were computed and refined, using a riding
model, with an isotropic temperature factor equal to 1.2 times the
equivalent temperature factor of the atoms that are linked. The
final R(on F) factor was 0.076, wR(on |F|2) = 0.146, and goodness
of fit = 1.277 for all observed reflections. Number of refined
parameters was 697. Max. shift/esd = 0.00, mean shift/esd = 0.00.
Max. and min. peaks in final difference synthesis were 1.837 and
-2.084 e A-3, respectively.
8a. A prismatic crystal (0.1 ꢀ 0.1 ꢀ 0.2 mm) was selected and
mounted on a MAR345 diffractometer with an image plate
detector. Unit-cell parameters were determined from 3930
[2-CH(Me)CO2Me-3,4-Ph2-6-Cl-C9H4N]BF4 (12b). 12b was
obtained using the same procedure as that described above from
140 mg (0.18 mmol) of cyclopalladated compound 3b, 105 mg
(0.54 mmol) of silver tetrafluoroborate, and 120 mg (0.67 mmol)
of diphenylacetylene. Yield: 130 mg (58%). 1H NMR (400 MHz,
(21) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.;
Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidorib, G.;
Spagnac, R. J. Appl. Crystallogr. 1999, 32, 115.
(22) Sheldrick, G. M. SHELX-97 A Program for Automatic Solution
of Crystal Structure; University Gottingen: Germany, 1997.
(23) International Tables of X-Ray Crystallography, Vol. IV; Kynoch
Press: Birmingham (UK), 1974; pp 99-100 and 149.
CDCl3, 298 K), δ (ppm): 10.34 (s, 1H, H4), 8.85 (d, 1H, JHH
8.8, H3), 8.17 (d, 1H, JHH = 8.8, JHH = 2.0, H2), 7.66 (dd, 1H,
HH = 1.9, Jpara = 0.6, H1), 7.50-7.25 (m, 10H, 2Ph), 5.64 (d,
=
J

224 Organometallics, Vol. 29, No. 1, 2010
Table 2. Crystallographic and Structure Refinement Data for Compounds 3c, 8a, 9c, and 12b
Albert et al.
3c
8a
9c
12b
empirical formula
fw
temperature
wavelength
cryst syst, space group
unit cell dimens
C
789.16
100(2) K
0.71069 A
26H30Cl4N2O4Pd2
C28H24Cl2NO2PPd CHCl3 2(C30H27ClNO2PPd) H2O 2[(C25H21NO2)BF4] 5H2
3
3
3
734.1
293(2) K
1230.71
293(2) K
0.71073 A
1069.46
90(2) K
0.71073 A
0.71073 A
triclinic, P1
monoclinic, P21/c
a = 11.2943(4) A
b = 16.2444(6) A
c = 33.4743(13) A
R = 90°
monoclinic, P21/c
a = 16.343(13) A
b = 8.898(6) A
c = 19.107(8) A
R = 90°
β = 99.43(4)°
γ = 90°
monoclinic, P21/c
a = 11.962(2) A
b = 26.247(5) A
c = 8.3818(15) A
R = 90°
β = 95.933(3)°
γ = 90°
a = 7.938(3) A
b = 11.264(3) A
c = 18.289(6) A
R = 90.93(2)°
β = 96.83(2)°
γ = 107.60(2)°
1545.3(9) A3
2, 1.578 Mg/m3
1.112 mm-1
736
β = 99.710(2)°
γ = 90°
volume
6053.5(4) A3
8, 1.732 Mg/m3
1.575 mm-1
3136
2741(3) A3
2617.6(8) A3
2, 1.357 Mg/m3
0.208 mm-1
1108
Z, calcd density
absorp coeff
F(000)
2, 1.491 Mg/m3
0.863 mm-1
1252
cryst size
θ range for data collection 1.23° to 26.37°
0.16 ꢀ 0.13 ꢀ 0.07 mm
0.2 ꢀ 0.1 ꢀ 0.1 mm
2.80° to 30.64°
-10 e h e 9
-16 e k e 14
-24 e l e 24
12 579/6936
[R(int) = 0.0362]
= 25.00°, 90.7%
empirical
0.2 ꢀ 0.1 ꢀ 0.1 mm
2.61° to 32.62°
-24 e h e 24
-11 e k e 11
-25 e l e 28
24 527/8167
[R(int) = 0.0460]
= 25.00°, 92.8%
empirical
0.43 ꢀ 0.26 ꢀ 0.09 mm
1.55° to 26.41°
limiting indices
-14 e h e 13
0 e k e 20
0 e l e 41
-14 e h e 14
-32 e k e 32
-10 e l e 10
22 166/5367
reflns collected/unique
7104/12 370
[R(int) = 0.0544]
= 26.37°, 99.9%
semiempirical from
equivalents
[R(int) = 0.0505]
= 26.41°, 99.9%
semiempirical from equivalents
completeness to θ
absorp corr
max. and min. transmn
refinement method
data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
0.8977 and 0.7867
0.89 and 0.87
0.92 and 0.90
0.9827 and 0.9209
full-matrix least-squares on F2
8167/10/334
0.727
12 370/1/697
1.277
R1 = 0.0763
wR2 = 0.1426
R1 = 0.0902
wR2 = 0.1468
6936/7/353
1.093
5367/2/348
1.138
R1 = 0.0548
wR2 = 0.1823
R1 = 0.0919
wR2 = 0.2078
R1 = 0.0436
wR2 = 0.1254
R1 = 0.0495
wR2 = 0.1290
0.0240(17)
R1 = 0.0403
wR2 = 0.0704
R1 = 0.1520
wR2 = 0.0878
R indices (all data)
extinction coeff
largest diff peak and hole
1.837 and -2.084 e A-3 0.852 and -0.519 e A-3
0.515 and -0.314 e A-3
1.141 and -0.398 e A-3
reflections (3° < θ < 31°) and refined by the least-squares
method. Intensities were collected with graphite-monochroma-
tized Mo KR radiation; 12 579 reflections were measured in the
range 2.80° e θ e 30.64°, 6936 of which were nonequivalent by
symmetry (Rint(on I) = 0.036); 6075 reflections were assumed as
observed applying the condition I > 2σ(I). Lorentz-polariza-
tion and absorption corrections were made. The structure
was solved by direct methods, using the SHELXS computer
program,24 and refined by the full-matrix least-squares method
with the SHELX97 computer program,22 using 125 792 reflec-
corrections were made. The structure was solved by direct meth-
ods, using the SHELXS computer program,24 and refined by the
full-matrix least-squares method with the SHELX97 computer
program,22 using 24 527 reflections; very negative intensities were
P
not assumed. The function minimized was w||Fo|2 - |Fc|2|2,
where w = [σ2(I) þ (0.0167P)2]-1, and P = (|Fo|2 þ 2|Fc|2)/3. f, f 0,
and f 0 were taken from International Tables of X-ray Crystal-
lography.23 All H atoms were computed and refined, using a riding
model, with an isotropic temperature factor equal to 1.2 times the
equivalent temperature factor of the atoms that are linked. The
final R(on F ) factor was 0.040, wR(on |F|2) = 0.070, and goodness
of fit = 0.727 for all observed reflections. Number of refined
parameters was 334. Max. shift/esd = 0.00, mean shift/esd = 0.00.
Max. and min. peaks in final difference synthesis were 0.515 and
-0.314 e A-3, respectively.
tions; very negative intensities were not assumed. The function
P
minimized was
w||Fo|2 - |Fc|2|2, where w = [σ2(I) þ
(0.0675P)2 þ 0.7493P]-1, and P = (|Fo|2 þ 2|Fc|2)/3. f, f 0, and
f 0 were taken from International Tables of X-ray Crystallogra-
phy.23 All H atoms were computed and refined, using a riding
model, with an isotropic temperature factor equal to 1.2 times
the equivalent temperature factor of the atoms that are linked.
The final R(on F) factor was 0.049, wR(on |F|2) = 0.129, and
goodness of fit = 1.093 for all observed reflections. Number of
refined parameters was 353. Max. shift/esd = 0.00, mean shift/
esd = 0.00. Max. and min. peaks in final difference synthesis
were 0.852 and -0.519 e A-3, respectively.
12b. A prismatic crystal (0.43 ꢀ 0.26 ꢀ 0.09 mm) was selected
and mounted on a Smart-CCD-1000 Bruker diffractometer.
Unit-cell parameters were determined from automatic centering
of 25 reflections (2.31° < θ < 26.23°) and refined by the least-
squares method. Intensities were collected with graphite-mono-
chromatized Mo KR radiation; 22 166 reflections were mea-
sured in the range 1.55 e θ e 26.41, 5367 of which were
nonequivalent by symmetry (Rint(on I) = 0.050); 3500 reflec-
tions were assumed as observed applying the condition
I > 2σ(I). Lorentz-polarization and absorption corrections
were made. The structure was solved by direct methods, using
the SHELXS computer program,24 and refined by the full-
matrix least-squares method with the SHELX97 computer
9c. A prismatic crystal (0.1 ꢀ 0.1 ꢀ 0.2 mm) was selected and
mounted on a MAR345 diffractometer with image plate detec-
tor. Unit-cell parameters were determined from 55 reflections
(3° <θ< 31°) and refined by the least-squares method. Intensities
were collected with graphite monochromatized Mo KR radiation;
24 527 reflections were measured in the range 2.61° e θ e 32.62°,
8167 of which were nonequivalent by symmetry (Rint(on I ) =
0.046); 3093 reflections were assumed as observed applying the
condition I > 2σ(I ). Lorentz-polarization but no absorption
program,22 using 22 166 reflections; very negative intensities
P
were not assumed. The function minimized was
w||F|2
-
|Fc|2|2, where w = [σ2(I) þ (0.0986P)2 þ 1.9906P]-1
,
and
P = (|Fo|2 þ 2 |Fc|2)/3. f, f 0, and f 0 were taken from International
Tables of X-ray Crystallography.23 All H atoms were computed
and refined, using a riding model, with an isotropic temperature
(24) Sheldrick, G. M. SHELXS A Program for Automatic Solution of
Crystal Structure; University of Gottingen: Germany, 1997.

Article
Organometallics, Vol. 29, No. 1, 2010 225
factor equal to 1.2 times the equivalent temperature factor
of the atoms that are linked. The final R(on F ) factor was
0.055, wR(on |F|2) = 0.1823, and goodness of fit = 1.138 for all
observed reflections. Number of refined parameters was 348.
Max. shift/esd = 0.000, mean shift/esd = 0.00. Max. and min.
crystallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; fax: (þ44)1223-336-033; e-mail:
deposit@ccdc.cam.ac.uk.
peaks in final difference synthesis were 1.141 and -0.398 e A-3
,
respectively.
Acknowledgment. We thank the Ministerio de
ꢁ
Educacion y Ciencia for financial suport (project:
CTQ2009-11501), and J.Z. thanks the Ministerio de
A summary of the crystallographic data for compounds 2c,
8a, 9c, and 12b and some details of the refinement are given in
Table 2. CCDC-749661, (3c) CCDC-749662 (8a), CCDC-749663
(9c), and CCDC-749664 (12b) contain the supplementary
ꢁ
Educacion y Ciencia for a fellowship.