A new method for high-yield cyclopalladation of primary and secondary amines. Atom-efficient open-to-air inexpensive synthesis of Buchwald-type precatalysts

Article abstract of DOI:10.1021/om200464s

A new method for high-yield cyclopalladation of primary and secondary amines involving the corresponding ammonium triflates, instead of the amines generally employed, is reported. The method is applied for the synthesis of Buchwald-type precatalysts [Pd(C,N-C₆H₄CH ₂CH(R′)NHR-2)X(phosphine)] that can be easily prepared by reaction of Pd(OAc)₂, 1 equiv of the ammonium triflate [PhCH ₂CH(R′)NH₂R]OTf, and an excess of NaX and then treating the resulting complexes [Pd₂(C,N-C₆H ₄CH₂CH(R′)NHR-2)₂(μ-X)₂] with the appropriate phosphine. This new method has several advantages over Buchwald's reported synthesis.

Full text of DOI:10.1021/om200464s

ARTICLE
pubs.acs.org/Organometallics
A New Method for High-Yield Cyclopalladation of Primary and
Secondary Amines. Atom-Efficient Open-to-Air Inexpensive Synthesis
of Buchwald-Type Precatalysts
Josꢀe Vicente,* Isabel Saura-Llamas,* María-Josꢀe Oliva-Madrid, and Josꢀe-Antonio García-Lꢀopez
Grupo de Química Organometꢀalica, Departamento de Química Inorgꢀanica, Facultad de Química, Universidad de Murcia, Apartado
4021, E-30071 Murcia, Spain
Delia Bautista
SAI, Universidad de Murcia, Apartado 4021, E-30071 Murcia, Spain
S Supporting Information
b
ABSTRACT: A new method for high-yield cyclopalladation of primary
and secondary amines involving the corresponding ammonium tri-
flates, instead of the amines generally employed, is reported. The
method is applied for the synthesis of Buchwald-type precatalysts
[Pd(C,N-C6H4CH2CH(R0)NHR-2)X(phosphine)] that can be
easily prepared by reaction of Pd(OAc)2, 1 equiv of the ammonium
triflate [PhCH2CH(R0)NH2R]OTf, and an excess of NaX and then
treating the resulting complexes [Pd2(C,N-C6H4CH2CH(R0)NHR-2)2(μ-X)2] with the appropriate phosphine. This new method
has several advantages over Buchwald's reported synthesis.
’ INTRODUCTION
the corresponding dimeric ortho-palladated acetato or chloro
complex. Metathesis reaction of this complex with NaBr ren-
dered the corresponding bromo derivative, which subsequently
reacted with PPh3 (molar ratio 1:2) to give the mononuclear
phosphino adduct. This method presented some advantages over
Buchwald’s method. Thus, the reactions were carried out without
precautions against air or moisture, no other organometallic
compound was used, the reagents were quite inexpensive, the
intermediates were easily isolable and stable, and the method
offered a great versatility to modify the nature of the ligands in the
Buchwald-type precatalyst.8 However, the phosphino cyclopalla-
dated complexes were obtained in poor yields (15ꢀ34%, based on
Pd(OAc)2).
Buchwald et al. have shown that ortho-palladated derivatives
of primary and secondary amines containing biarylmonophos-
phines are excellent precatalysts for CꢀC1 and CꢀN cross-
coupling reactions.2,3 These precatalysts are particularly useful
for substrates unstable at elevated reaction temperatures. They
are prepared via a two-step one- or two-pot synthesis (Scheme 1)
from [PdCl2(TMEDA)] (TMEDA = N,N,N0,N0-tetramethyl-
ethylenediamine), MeLi, the free phosphine, and the correspond-
ing 2-chlorophenethylamine or 2-(2-chlorophenyl)-N-methyl-
ethanamine in moderate to good yields (61ꢀ85%).2 However, the
reaction conditions are not straightforward: (1) an argon atmo-
sphere is required; (2) the intermediate [PdMe2(TMEDA)] can
be isolated (in some cases it is required because it is used asstarting
material), but it has tobestored inside a nitrogen-filled gloveboxor
in a freezer under argon; moreover, this complex shows exother-
mic decomposition between 115 and 130 °C; (3) if the 2-haloar-
ylalkylamine is not commercially available, it has to be otherwise
prepared, as it happens with the 2-(2-chlorophenyl)-N-methyl-
ethanamine;2 and (4) the nature of the halo ligand is determined
by that of the aryl halide, although it could be changed by metathesis,
adding a new step to the process.
Here, we report a new method of synthesis of a variety of halo
complexes of Pd(II) containing ortho-metalated primary or
secondary phenethylamines, which adds to the advantages of
our previously reported one, the good yields of the cyclopalla-
dated complexes and the phosphino derivatives.9
’ RESULTS AND DISCUSSION
Synthesis. The ammonium triflate derived from phenethyl-
amine (PhCH2CH2NH3)OTf (A), L-phenylalanine methyl ester
(S)-(PhCH2CH(CO2Me)NH3)OTf (B), or N-methylpheneth-
ylamine (PhCH2CH2NH2Me)OTf (C) reacted with Pd(OAc)2
in a 1:1 molar ratio, in acetonitrile at 75ꢀ78 °C, to give HOAc
and, likely, intermediate I, which underwent an ortho-metalation
Back in 1997, we reported a general method to ortho-palladate
primary arylalkylamines, which allowed the synthesis of five- and
six-membered palladacycles (the synthesis of phenethylamine
derivatives is illustrated in Scheme 2), even when the aryl ring
contained electron-withdrawing substituents.4ꢀ7 The reaction
involved equimolecular amounts of the free amine or its hydro-
chloride and palladium acetate in acetonitrile at 80 °C, affording
Received: May 30, 2011
Published: July 28, 2011
r
2011 American Chemical Society
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Scheme 1. Buchwald’s Synthesis of Palladacycles Containing
Ortho-metalated Phenethylamines
Scheme 3. Improved Synthesis of Palladacycles Containing
Ortho-metalated Phenethylaminesa
Scheme 2. Synthesis of Ortho-palladated Phenethylamine
Derivatives Using the Free Amines or Their Corresponding
Hydrochlorides
a The anion of the cationic species is TfOꢀ.
reaction to afford the solvento complex II (Scheme 3),10,11 which
further reacted with NaX (X = Cl, Br) to render the halo-bridged
cyclopalladated complex [Pd2(C,N-C6H4CH2CH(R0)NHR-
2)2(μ-X)2] (R = R0 = H, X = Cl (1a-Cl), Br (1a-Br); R = H,
R0 = CO2Me, X = Cl (1b-Cl), Br (1b-Br); R = Me, R0 = H, X = Cl
(1c-Cl), Br (1c-Br)). The two steps of the global reaction are
carried out in the same pot, replacing acetonitrile by acetone
before adding the sodium salt. The yields of complexes 1 are in
the range 70ꢀ98%, in contrast with those obtained using the free
amine or its hydrochloride (see below). The different yields can
be explained on the basis of the different electrophilicity of the
precursor of II, i.e., I when the ammonium triflate is used. Thus,
the free amine or its hydrochloride would afford a neutral
intermediate resulting from replacing the solvent ligand (S) in
I by an acetato or chloro ligand. However, using the ammonium
triflate, the weak donor ligand triflato does not replace S,
affording I, the cationic nature of which enhances the electro-
philicity of palladium(II) and facilitates the ortho-metalation
process. In mechanistic studies on ortho-palladation of arylalk-
ylamines, anintermediatesuchasIhas been postulated.12 A solvento
complex similar to II has been postulated as an intermediate in
the ortho-metalation of R-methylbenzylamine starting from
[PdCl2{NH2CH(Me)Ph}2] and AgClO4 (1:2 molar ratio) and
using acetone as solvent.13 The synthesis of complexes 1a-Br, 1b-
Cl, 1b-Br, and 1c-Br had been previously reported by us,
following a similar method to that described in Scheme 2,
although 1b-Cl was not isolated in a pure form and 1a-Br, 1b-
Br, and 1c-Br were obtained in lower yields (1a-Br: 30%; 1b-Br:
49%; 1c-Br, 65%).7,14
When trying to use an analogous procedure to prepare the
iodo-bridged complexes derived from the ammonium triflates B
and C, intractable mixtures were obtained. Similar results were
achieved when the addition of NaI was carried out in acetonitrile,
instead of acetone. It is likely that a very unstable cationic iodo
derivative, [Pd(C,N-C6H4CH2CH(R0)NH2-2)I(solvent)]+, formed
during the reaction, which decomposed to give unidentified
products. The enhanced electrophilicity of the palladium center
in cationic or iodine-containing cyclopalladated complexes and
their increased facility to undergo reductive elimination is well
documented.15 However, the reaction of A, Pd(OAc)2, and NaI
in the same conditions used to prepare 1a-Cl or 1a-Br rendered the
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Chart 1. Numbering Scheme for Ortho-metalated
Palladacycles
Figure 2. X-ray thermal ellipsoid plot (50% probability) of complex 4
showing the labeling scheme (hydrogen atoms have been omitted for
clarity). Selected bond lengths (Å) and angles (deg): Pd(1)ꢀC(1) =
2.009(2), Pd(1)ꢀN(1)
=
2.109(2), Pd(1)ꢀI(1)
= 2.7279(3),
Pd(1)ꢀP(1) = 2.2630(6), N(1)ꢀC(9) = 1.282(3); C(1)ꢀPd(1)ꢀN-
(1) = 82.90(8), N(1)ꢀPd(1)ꢀI(1) = 89.39(5), I(1)ꢀPd(1)ꢀP(1) =
94.081(17), P(1)ꢀPd(1)ꢀC(1) = 93.56(7).
Figure 1. X-ray thermal ellipsoid plot (50% probability) of complex 3b-
I CHCl3 showing the labeling scheme (the solvent molecule and all the
3
hydrogen atoms, excluding that involved in the hydrogen bond, have
been omitted for clarity). Selected bond lengths (Å) and angles (deg):
Pd(1)ꢀC(1) = 2.032(5), Pd(1)ꢀN(1) = 2.126(4), Pd(1)ꢀI(1) =
2.7060(5), Pd(1)ꢀP(1) = 2.2848(12); C(1)ꢀPd(1)ꢀN(1) = 84.32-
(17), N(1)ꢀPd(1)ꢀI(1) = 86.60(12), I(1)ꢀPd(1)ꢀP(1) = 93.82(3),
P(1)ꢀPd(1)ꢀC(1) = 95.29(13).
dimeric iodo-bridged ortho-palladated complex [Pd2(C,N-C6H4-
CH2CH2NdCMe2-2)2(μ-I)2] (2), which contained the imine aris-
ing from the condensation of phenethylamine and acetone
(Scheme 3). Following an alternative method, the iodo-bridged
ortho-metalated complexes [Pd2(C,N-C6H4CH2CH(R0)NHR-2)2
(μ-I)2] (R = R0 = H, X = I (1a-I); R = H, R0 = CO2Me, X = I
(1b-I); R = Me, R0 = H, X = I (1c-I)) were easily prepared in good
yields by metathesis reaction of complexes 1a-OAc, 1b-Cl, and 1c-Cl
with an excess of NaI in acetone (Scheme 3). We reported previously
the synthesis of 1a-OAc by palladation of phenethylamine.16
Figure 3. View of the hydrogen bond interactions in complex 3b-
It is well known that the halo bridges in dimeric ortho-
palladated complexes containing primary arylalkylamines are
easily split by various neutral ligands, including phosphines,
pyridines, or isocyanides.4,5,11,17 Thus, the reaction of complex
1a-Cl, 1a-Br, or 1b-I with two equivalents of 2-dicyclohexylphos-
phino-20,60-dimethoxyphenyl (SPhos) allowed the synthesis of
the mononuclear phosphino derivative 3a-Cl, 3a-Br, or 3b-I.
Similarly, the imino complex 2 reacted with PPh3 (in a 1:2 molar
ratio) to give compound 4. Given the great stability of complexes
1, it seems that any study on the catalytic properties of Buchwald-type
complexes 3 would gain flexibility if different phosphines can be
tested using complexes 1 as starting materials. Complex 3a-Cl has
I CHCl3. Only atoms involved in the hydrogen bonding are labeled.
3
been previously prepared by Buchwald et al. via his two-step one-pot
synthesis (Scheme 1) in an 85% yield and used as precatalyst in
coupling reactions.2 Although the overall yield for the synthesis of
complex 3a-Cl using our method is slightly lower (78%), the
advantages of our method are evident: (1) the starting materials
(see Scheme 3) are easily available, and all but the common SPhos are
much cheaper; (2) the reactions are carried out without special
precautions against air or moisture; (3) the dinuclear halo-bridged
ortho-metalated complexes are extraordinarily stable in solid state and
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can be stored for very long periods of time; (4) these dinuclear
complexes are very versatile, as different neutral ligands can split the
halo bridges to give mononuclear derivatives, such as other P-donor
(other bulky phosphines or chiral ones) or N-donor (amines,
pyridines) ligands; and (5) our method allows to change in a facile
way the cyclometalated phenethylamine fragment as well as the halo
ligand coordinated to Pd(II), thus modifying the chemical and
physical properties of the palladacycle.18
Trifluoromethanesulfonic acid (triflic acid), 2-(phenyl)ethylamine
(phenethylamine),L-phenylalanine methyl ester, N-methylphenethylamine,
2-dicyclohexylphosphino-20,60-dimethoxyphenyl (SPhos; Aldrich), PPh3
(Fluka), NaCl (J. T. Baker), NaBr, NaI (Scharlau), and Pd(OAc)2
(Johnson Matthey) were used as received. Chart 1 gives the numbering
scheme for the palladacycles.
Synthesis of [C6H5CH2CH2NH3]OTf (A). Triflic acid (2.5 mL of
a solution that contains 11.3 mmol/L, 28.25 mmol) was slowly added to
a solution of phenethylamine (3 mL, 23.89 mmol) in Et2O (50 mL), and
the resulting white suspension was vigorously stirred for 20 min. The
mixture was filtered, and the solid was washed with Et2O (2 ꢁ 5 mL) and
air-dried to give compound A as a white solid. Yield: 5.46 g, 20.13 mmol,
84%. Mp: 204 °C. ΛM (Ωꢀ1 cm2 molꢀ1): 125 (7.4 ꢁ 10ꢀ4 M). Anal.
Calcd for C9H12F3NO3S (271.257): C, 39.85; H, 4.46; N, 5.16; S, 11.82.
Found: C, 39.81; H, 4.41; N, 5.18; S, 11.79. IR (cmꢀ1): ν(NH) 3177 vs.
1H NMR (400.91 MHz, DMSO-d6): δ 2.84 (m, 2 H, CH2Ar), 3.04 (m,
2 H, CH2N), 7.22ꢀ7.27 (m, 3 H, p-H and o- or m-H, C6H5), 7.30ꢀ7.35
(m, 2 H, o- or m-H, C6H5), 7.73 (br s, 3 H, NH3). 13C NMR (100.81
MHz): δ 33.1 (s, CH2Ar), 40.0 (s, CH2N), 126.8 (s, p-CH, C6H5),
128.6 (s, o- or m-CH, C6H5), 128.7 (s, o- or m-CH, C6H5), 137.2 (s, i-C,
C6H5).
Synthesis of (S)-[C6H5CH2CH(CO2Me)NH3]OTf (B). Na2CO3
(600 mg, 5.66 mmol) was added to a solution of L-phenylalanine methyl
ester hydrochloride (1.00 g, 4.64 mmol) in water (15 mL), and the
resulting solution was stirred for 15 min. The reaction mixture was
extracted with CH2Cl2 (3 ꢁ 15 mL), and the combined organic layers
were dried over MgSO4. The suspension was filtered, the filtrate was
concentrated to ca. 5 mL, triflic acid (0.5 mL of a solution that contains
11.3 mmol/L, 5.65 mmol) was slowly added, and the resulting white
suspension was vigorously stirred for 10 min. The mixture was filtered,
and the solid was washed with Et2O (2 ꢁ 5 mL) and air-dried to give a
first crop of compound B as a white solid (1.10 g). The filtrate was
concentrated to ca. 3 mL, and Et2O (20 mL) was added. The suspension
was filtered, and the solid was washed with Et2O (2 ꢁ 5 mL) and air-
dried to give a second crop of compound B as a white solid (300 mg).
Yield: 1.40 g, 4.25 mmol, 92%. Mp: 151 °C. ΛM (Ωꢀ1 cm2 molꢀ1): 126
(5.2 ꢁ 10ꢀ4 M). Anal. Calcd for C11H14F3NO5S (329.293): C, 40.12;
H, 4.29; N, 4.25; S, 9.74. Found: C, 39.90; H, 4.40; N, 4.23, S, 9.57. IR
(cmꢀ1): ν(NH) 3224 vs; ν(CO) 1741 vs. 1H NMR (300.1 MHz,
DMSO-d6): δ 3.06 (m, 2 H, CH2), 3.69 (m, 2 H, Me), 4.33 (t, 1 H, CH,
3JHH = 6.6 Hz), 7.18ꢀ7.23 (m, 3 H, o-H, C6H5), 7.25ꢀ7.37 (m, 3 H, m-
H and p-H, C6H5), 8.37 (br s, 3 H, NH3). 13C NMR (75.45 MHz,
DMSO-d6): δ 36.0 (s, CH2), 52.7 (s, Me), 53.2 (s, CH), 120.7 (q, CF3,
1JCF = 322.2 Hz), 127.4 (s, p-CH, C6H5), 128.7 (s, m-CH, C6H5), 129.4
(s, o-CH, C6H5), 134.4 (s, i-C, C6H5), 169.5 (s, CO).
NMR Spectra. The 1H and 13C NMR spectra of complexes 1a-
Br, 1b-Br, 1c-Br, and 3a-Cl are in agreement with the reported
data.2,4,7,14 For all the new compounds, their spectroscopic data
correspond with the proposed structures. Thus, the halo-bridged
ortho-metalated complexes exhibit in the aromatic region of their
1H NMR spectra (DMSO-d6) a set of two signals corresponding
to the four remaning protons of the cyclopalladated ring: a
doublet (1a-Cl, 1a-I, 1b-Cl, 1c-Cl, 2) or a broad singlet (1b-I, 1c-
I) assigned to H6 (δ 7.43ꢀ7.51 ppm; see Chart 1 for the
numbering scheme) and a multiplet assigned to H3 + H4 +
H5 (δ 6.70ꢀ7.10 ppm). In the 13C NMR spectra of these
complexes, the resonances due to the carbon atoms bonded to
Pd, when observed, are deshielded with respect to that of the
corresponding triflate (Δδ = 18ꢀ20 ppm), as it occurs in other
cyclopalladated complexes.16 The protons of the NH2 or CH2
groups resonate as one broad signal in the complexes containing
phenethylamine, while they become diastereotopic for L-phenyl-
alanine methyl ester and N-methylphenethylamine derivatives.
The 31P NMR spectra of complexes 3a-Cl, 3a-Br, and 3b-I show
a very broad singlet, suggesting dissociation of the phosphine
favored by its steric requirement.
Crystal Structures. The crystal structures of complexes 3b-
I CHCl3 (Figure 1) and 4 (Figure 2) have been determined by
3
X-ray diffraction studies, and they show the palladium atom in a
slightly distorted (3b-I CHCl3) or distorted (4) square-planar
3
environment (mean deviation from the plane: 0.0224 Å, 3b-
I CHCl3; 0.0877 Å, 4) with dihedral angles of 2.1° (3b-
3
3
I CHCl3) and 9.6° (4) between the N(1)ꢀPd(1)ꢀC(1) and
P(1)ꢀPd(1)ꢀI(1) planes. In both complexes, the chelated
amino (3b-I CHCl3) or imino ligand (4) forms a six-membered
3
metallacycle with a boat conformation. The features of complexes
3b-I CHCl3 and 4 are similar to those of analogous phosphino
3
complexes containing primary ortho-metalated phenethyl-
amines2,4,5 or related imino ligands.19 The X-ray crystallographic
study reveals the S absolute configuration of the R-carbon
stereocenter in complex 3b-I CHCl3. This complex exhibits an
3
Synthesis of [C6H5CH2CH2NH2Me]OTf (C). Triflic acid (1.5 mL
of a solution that contains 11.3 mmol/L, 16.95 mmol) was slowly added
to a solution of N-methylphenethylamine (2.5 mL, 17.19 mmol) in Et2O
(40 mL), and the resulting white suspension was vigorously stirred for
15 min. The mixture was filtered, and the solid was washed with Et2O
(2 ꢁ 5 mL) and air-dried to give compound C as a white solid. Yield:
4.56 g, 15.98 mmol, 94%. Mp: 124 °C. ΛM (Ωꢀ1 cm2 molꢀ1): 116 (7.43 ꢁ
10ꢀ4 M). Anal. Calcd for C10H14F3NO3S (285.283): C, 42.10; H, 4.95;
N, 4.91; S, 11.24. Found: C, 42.35; H, 4.75; N, 5.03; S, 11.27. IR (cmꢀ1):
ν(NH) 3219 s, 3030 s. 1H NMR (300.1 MHz, DMSO-d6): δ 2.59 (s, 3
H, Me), 2.88 (m, 2 H, CH2Ar), 3.14 (m, 2 H, CH2N), 7.22ꢀ7.28 (m, 3
H, o- and p-H, C6H5), 7.31ꢀ7.37 (m, 2 H, m-H, C6H5), 8.32 (br s, 2 H,
NH2). 13C NMR (75.45 MHz, DMSO-d6): δ 31.5 (s, CH2Ar), 32.6 (s,
Me), 49.1 (s, CH2N), 126.8 (s, p-CH, C6H5), 128.7 (s, o-CH and p-CH,
C6H5), 137.0 (s, i-C, C6H5).
intramolecular nonclassical hydrogen bond between the iodine
atom and one hydrogen of the cyclohexyl group; besides, each
molecule is connected to another two through hydrogen bonds
between the oxygen atom of the carbonyl group and one of the
hydrogen atoms of the OMe substituent on the biaryl group,
giving rise to zigzag chains along the b-axis (Figure 3).
’ EXPERIMENTAL SECTION
General Procedures. Infrared spectra were recorded on a Perkin-
Elmer 16F-PC-FT spectrometer. C, H, N, and S analyses, conductance
measurements, and melting point determinations were carried out as
described elsewhere.14 Unless otherwise stated, NMR spectra were
recorded in CDCl3 in Bruker Avance 300 or 400 spectrometers.
Chemical shifts are referenced to TMS [1H and 13C{1H}]. Signals in
the 1H and 13C NMR spectra of all complexes were assigned with the
help of HMQC and HMBC techniques. Reactions were carried out at
room temperature without special precautions against moisture.
Synthesis of [Pd2(C,N-C6H4CH2CH2NH2-2)2(μ-OAc)2] (1a-
OAc). Phenethylamine (0.5 mL, 3.982 mmol) was added to a suspen-
sion of Pd(OAc)2 (894 mg, 3.982 mmol) in acetonitrile (55 mL), and
the resulting mixture was heated at 60 °C for 2 h and then at 78 °C for 6 h.
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Decomposition to metallic palladium was observed. The mixture was
filtered through a plug of Celite/Na2CO3, the solvent was removed from
the filtrate, and CH2Cl2 (2 mL) and Et2O (30 mL) were added. The
suspension was filtered, and the solid was washed with Et2O (2 ꢁ 5 mL)
and air-dried to give complex 1a-OAc as a yellow solid. Yield: 815 mg,
1.427 mmol, 72%. Dec pt: 148 °C. Anal. Calcd for C20H26N2O4Pd2
(571.238): C, 42.05; H, 4.59; N, 4.90. Found: C, 41.57; H, 4.57; N, 4.73.
IR (cmꢀ1): ν(NH) 3319 m, 3301 s, 3193 s, 3112 s; ν(CO) 1594 vs, 1550
vs. 1H NMR (300.10 MHz, DMSO-d6): δ 1.77 (s, 3 H, Me), 2.35 (br s, 2
H, CH2N), 2.90 (m, 2 H, CH2Ar), 5.68 (br s, 2 H, NH2), 6.85ꢀ6.97 (m,
to give complex 1a-I as a dark orange solid (120 mg). The filtrate was
concentrated to ca. 4 mL, and n-pentane (20 mL) was added. The
suspension was filtered, and the solid was washed with n-pentane (2 ꢁ
5 mL) and air-dried to give a second crop of complex 1a-I as a dark orange
solid (110 mg). Yield:230 mg, 0.325 mmol, 93%. Mp: 158°C. Anal. Calcd
for C16H20I2N2Pd2 (706.992): C, 27.18; H, 2.85; N, 3.96. Found: C,
27.08; H, 2.67; N, 3.86. IR (cmꢀ1): ν(NH) 3180 m, 3282 m. 1H NMR
(300.1 MHz, DMSO-d6): δ 2.37 (m, 2 H, CH2N), 2.87 (“t”, 2 H, CH2Ar,
3JHH = 5.4 Hz), 4.74 (br s, 2 H, NH2), 6.70ꢀ7.07 (m, 3 H, H3 + H4 +
H5), 7.50 (d, 1 H, H6, 3JHH = 7.2 Hz). 13C NMR (75.45 MHz, DMSO-
d6): δ 37.2 (s, CH2N), 42.3 (s, CH2Ar), 124.3 (br s, CH, C4 + C5), 126.1
(s, CH, C3), 128.5 (s, CH, C6), 139.7 (s, C2). The 13C resonance
corresponding to C1 (CꢀPd) was not observed.
3
3 H, H3 + H4 + H5), 7.42 (d, 1 H, H6, JHH = 7.2 Hz). 13C NMR
(100.81 MHz, DMSO-d6): δ 29.9 (s, Me), 36.4 (s, CH2N), 42.9 (s,
CH2Ar), 124.4 (s, CH, C4 + C5), 125.9 (s, CH, C3), 134.0 (s, CH, C6),
140.1 (s, C2), 143.7 (s, C1, CꢀPd), 177.1 (br s, CO). The synthesis of
1a-OAc was previously reported by us, although without experimental
details and spectroscopical data.16
Synthesis of (S,S)-[Pd2{C,N-C6H4CH2CH(CO2Me)NH2-2}2
(μ-Cl)2] (1b-Cl). The ammonium triflate B (1200 mg, 3.645 mmol)
was added to a suspension of Pd(OAc)2 (820 mg, 3.653 mmol) in
acetonitrile (50 mL), and the resulting solution was heated at 60 °C for 2
h and then at 79 °C for 4 h. The mixture was filtered through a plug of
Celite/Na2CO3, the solvent was removed from the filtrate, acetone
(40 mL) and NaCl (3000 mg, 51.33 mmol) were added, and the
suspension was stirred for 12 h. The solvent was removed, and CH2Cl2
(40 mL) was added. The mixture was filtered through a plug of Celite,
the filtrate was concentrated to ca. 2 mL, and Et2O (30 mL) was added.
The suspension was filtered, and the solid was washed with Et2O (2 ꢁ
5 mL) and air-dried to give a first crop of the complex 1b-Cl as an orange
solid (700 mg, 1.093 mmol). The filtrate was concentrated to ca. 4 mL,
and n-hexane (20 mL) was added. The suspension was filtered, and the
solid was washed with n-hexane (2 ꢁ 5 mL) and air-dried to give a
second crop of the complex 1b-Cl as an orange solid (450 mg, 0.703
mmol). Yield: 1150 mg, 2.796 mmol, 98%. Mp: 142 °C dec. Anal. Calcd
for C20H24Cl2N2O4Pd2 (640.128): C, 37.52; H, 3.79; N, 4.37. Found:
C, 37.57; H, 3.89; N, 4.49. IR (cmꢀ1): ν(NH) 3284 m, 3232 m; ν(CO)
Synthesis of [Pd2(C,N-C6H4CH2CH2NH2-2)2(μ-Cl)2] (1a-Cl).
The ammonium triflate A (1000 mg, 3.686 mmol) was added to a
suspension of Pd(OAc)2 (827.6 mg, 3.686 mmol) in acetonitrile
(50 mL), and the resulting solution was heated at 60 °C for 2 h and
then at 78 °C for 4 h. The mixture was filtered through a plug of Celite/
Na2CO3, the solvent was removed from the filtrate, acetone (30 mL)
and NaCl (2000 mg, 34.22 mmol) were added, and the suspension was
stirred for 12 h. The mixture was filtered, the solvent was removed from
the filtrate, and CH2Cl2 (40 mL) was added. The suspension was filtered
through a plug of Celite, solvent was removed from the filtrate, and the
residue was vigorously stirred in Et2O (15 mL) for 15 min. The
suspension was filtered, and the solid was washed with Et2O (2 ꢁ
5 mL) and air-dried to give complex 1a-Cl as a pale orange solid. Yield:
886 mg, 1.691 mmol, 92%. Dec pt: 163 °C. Anal. Calcd for
C16H20Cl2N2Pd2 (524.056): C, 36.67; H, 3.85; N, 5.35. Found: C,
36.43; H, 3.87; N, 5.26. IR (cmꢀ1): ν(NH) 3300 s, 3228 m. 1H NMR
(300.10 MHz, DMSO-d6): δ 2.33 (br s, 2 H, CH2N), 2.83 (m, 2 H,
CH2Ar), 4.75 (br s, 2 H, NH2), 6.85ꢀ6.97 (m, 3 H, H3 + H4 + H5), 7.46
(d, 1 H, H6, 3JHH = 7.5 Hz). 13C NMR (100.81 MHz, DMSO-d6): δ 37.3
(s, CH2N), 42.7 (s, CH2Ar), 124.5 (s, CH, C4 + C5), 125.9 (s, CH, C3),
133.9 (s, CH, C6), 140.0 (s, C2), 147.4 (s, C1, CꢀPd).
1735 s. 1H NMR (400.91 MHz, DMSO-d6): 3.10 (dd, 1 H, CH2, 2JHH
=
13.2, 3JHH = 9.6 Hz), 3.20 (dd, 1 H, CH2, 2JHH = 13.2, 3JHH = 3.6 Hz),
3.27ꢀ3.35 (m, partially obscured by the signal of H2O of the deuterated
solvent, 1 H, CH), 4.46 (br s, 1 H, NH2), 5.49 (m, 1 H, NH2), 6.92ꢀ7.00
(m, 3 H, H3 + H4 + H5), 7.45 (d, 1 H, H6, 3JHH = 7.6 Hz). 13C NMR
(100.81 MHz, DMSO-d6): δ 45.5 (s, CH2), 50.2 (s, CH), 52.8 (s, Me),
124.7 (s, CH, C4), 125.3 (s, CH, C5), 126.6 (s, CH, C3), 133.4 (s, CH,
C6), 137.7 (s, C2), 147.6 (s, C1, CꢀPd), 172.2 (s, CO).
Synthesis of [Pd2(C,N-C6H4CH2CH2NH2-2)2(μ-Br)2] (1a-Br).
The ammonium triflate A (1000 mg, 3.686 mmol) was added to a
suspension of Pd(OAc)2 (828 mg, 3.688 mmol) in acetonitrile (50 mL),
and the resulting solution was heated at 60 °C for 2 h and then at 78 °C
for 3.5 h. The mixture was filtered through a plug of Celite/Na2CO3, the
solvent was removed from the filtrate, acetone (30 mL) and NaBr (2000
mg, 19.44 mmol) were added, and the suspension was stirred for 18 h.
Solvent was removed, and the residue was vigorously stirred in Et2O
(25 mL) for 15 min. The suspension was filtered, and the solid was
washed with H2O (3 ꢁ 10 mL) and Et2O (3 ꢁ 5 mL) and air-dried to
give complex 1a-Br as a yellow solid. Yield: 840 mg, 1.37 mmol, 74%.
Dec pt: 158 °C. Anal. Calcd for C16H20Br2N2Pd2 (612.992): C, 31.35;
H, 3.29; N, 4.57. Found: C, 31.36; H, 3.18; N, 4.54. IR (cmꢀ1): ν(NH)
3265 s, 3218 w. 1H NMR (400.91 MHz, DMSO-d6): δ 2.35 (m, 2 H,
CH2N), 2.85 (“t”, 2 H, CH2Ar, 3JHH = 5.6 Hz), 4.75 (br s, 2 H, NH2),
6.85ꢀ6.96 (m, 3 H, H3 + H4 + H5), 7.46 (d, 1 H, H6, 3JHH = 7.2 Hz).
13C NMR (100.81 MHz, DMSO-d6): δ 37.3 (s, CH2N), 42.5 (s,
CH2Ar), 124.6 (br s, CH, C4 + C5), 126.0 (s, CH, C3), 133.4 (s,
CH, C6), 139.7 (s, C2), 149.1 (br s, C1, CꢀPd). Spectroscopic data are
in accordance with the data reported in the literature.4
Synthesis of (S,S)-[Pd2{C,N-C6H4CH2CH(CO2Me)NH2-2}2
(μ-Br)2] (1b-Br). The ammonium triflate B (1500 mg, 4.57 mmol)
was added to a suspension of Pd(OAc)2 (1028 mg, 4.58 mmol) in
acetonitrile (50 mL), and the resulting solution was heated at 65 °C for 2
h and then at 78 °C for 4 h. The mixture was filtered through a plug of
Celite and Na2CO3, the solvent was removed form the filtrate, acetone
(30 mL) and NaBr (3000 mg, 29.16 mmol) were added, and the
suspension was stirred for 12 h. The solvent was removed, and CH2Cl2
(40 mL) was added. The mixture was filtered through a plug of Celite,
the filtrate was concentrated to ca. 2 mL, and Et2O (40 mL) was added.
The suspension was filtered, and the solid was washed with Et2O (2 ꢁ
5 mL) and air-dried to give a first crop of the complex 1b-Br as a pale
orange solid (972 mg, 1.33 mmol). The filtrate was concentrated to ca.
5 mL, and n-pentane (30 mL) was added. The suspension was filtered,
and the solid was washed with n-pentane (2 ꢁ 5 mL) and air-dried to
give a second crop of the complex 1b-Br as a pale orange solid (510 mg,
0.70 mmol). Yield: 1.482 g, 2.03 mmol, 89%. Anal. Calcd for
C20H24Br2N2O4Pd2 (729.064): C, 32.95; H, 3.32; N, 3.84. Found: C,
32.79; H, 3.04; N, 3.85. IR (cmꢀ1): ν(NH) 3278 w, 3233 w; ν(CO)
1733 s. Spectroscopic data are in accordance with the data reported in
the literature.7
Synthesis of [Pd2(C,N-C6H4CH2CH2NH2-2)2(μ-I)2] (1a-I).
NaI (525 mg, 3.50 mmol) was added to a solution of 1a-OAc (200 mg,
0.350 mmol) in acetone (50 mL), and the suspension was stirred for 16 h.
Solvent was removed, CH2Cl2 (40 mL) was added, and the resulting
suspension was filtered through a plug of Celite. The filtrate was
concentrated to ca. 2 mL, and Et2O (30 mL) was added. The suspension
was filtered, and the solid was washed with Et2O (2 ꢁ 5 mL) and air-dried
Synthesis of (S,S)-[Pd2{C,N-C6H4CH2CH(CO2Me)NH2-2}2
(μ-I)2] (1b-I). NaI (470 mg, 3.13 mmol) was added to a solution of
1b-Cl (200 mg, 0.312 mmol) in acetone (50 mL), and the suspension
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ARTICLE
was stirred for 16 h. Solvent was removed, CH2Cl2 (40 mL) was added,
and the resulting suspension was filtered through a plug of Celite. The
filtrate was concentrated to ca. 2 mL, and Et2O (30 mL) was added. The
suspension was filtered, and the solid was washed with Et2O (2 ꢁ 5 mL)
and air-dried to give complex 1b-I as a dark orange solid (190 mg). Yield:
230 mg, 0.231 mmol, 74%. Mp: 179 °C dec. Anal. Calcd for C20H24I2-
N2O4Pd2 (823.07): C, 29.19; H, 2.94; N, 3.40. Found: C, 28.90; H, 2.81;
N, 3.10. IR (cmꢀ1): ν(NH) 3241 w, 3172 w; ν(CO) 1724 vs. 1H NMR
(400.91 MHz, DMSO-d6): 3.11 (br m, 1 H, CH2), 3.20 (dd, 1 H, CH2,
2JHH = 13.2, 3JHH = 3.6 Hz), 3.34ꢀ3.41 (br m, partially obscured by the
signal of H2O of the deuterated solvent, 1 H, CH), 3.70 (s, 3 H, Me),
4.57 (br s, 1 H, NH2), 5.38 (br s, 1 H, NH2), 6.70ꢀ7.05 (m, 3 H, H3 +
H4 + H5), 7.51 (br s, 1 H, H6). 13C NMR (100.81 MHz, DMSO-d6): δ
45.3 (br s, CH2), 50.1 (s, CH), 52.8 (s, Me), 125.0 (br s, CH), 126.7 (s,
CH), 137.3 (s, C2), 172.3 (s, CO). The 13C resonance corresponding to
C1 (CꢀPd) was not observed.
was filtered, and the solid was washed with Et2O (2 ꢁ 5 mL) and air-
dried to give complex 1c-I as a dark orange solid. Yield: 153 mg, 0.208
mmol, 83%. Mp: 155 °C dec. Calcd for C18H24I2N2Pd2 (735.052): C,
29.41; H, 3.29; N, 3.81. Found: C, 29.53; H, 2.84; N, 3.74. IR (cmꢀ1):
ν(NH) 3484 m, 3434 m, 3236 m. 1H NMR (400.91 MHz, DMSO-d6):
δ 1.71 (br s, 1 H, CH2N), 2.26 (d, 3 H, Me, 3JHH = 5.6 Hz), 2.85 (br m, 1
H, CH2Ar), 2.91ꢀ3.20 (m, 2 H, 1 H of CH2Ar + 1 H of CH2N), 5.43
(br s, 1 H, NH), 6.70ꢀ7.05 (m, 3 H, H3 + H4 + H5), 7.43 (br s, 1 H,
H6). 13C NMR (100.81 MHz, DMSO-d6): δ 40.4 (s, CH2Ar), 42.8 (br s,
Me), 49.4 (s, CH2N), 124.2 (br s, CH), 126.0 (s, CH), 139.7 (br s, C2).
The 13C resonance corresponding to C1 (CꢀPd) was not observed.
Synthesis of [Pd2(C,N-C6H4CH2CH2NdCMe2-2)2(μ-I)2] (2).
The ammonium triflate A (1000 mg, 3.686 mmol) was added to a
suspension of Pd(OAc)2 (828 mg, 3.688 mmol) in acetonitrile (50 mL),
and the resulting solution was heated at 78 °C for 4 h. The mixture was
filtered through a plug of Celite/Na2CO3, the solvent was removed from
the filtrate, acetone (30 mL) and NaI (2000 mg, 13.34 mmol) were
added, and the suspension was stirred for 18 h. The solvent was
removed, and the residue was stirred in Et2O (30 mL) for 15 min.
The suspension was filtered, and the solid was washed with H2O (3 ꢁ
10 mL), acetone (2 ꢁ 5 mL), and Et2O (2 ꢁ 5 mL) and air-dried to give
complex 2 as a bright yellow solid. Yield: 952 mg, 1.209 mmol, 66%. Dec
pt: 198 °C. Anal. Calcd for C22H28I2N2Pd2 (787.088): C, 33.57; H, 3.58;
N, 3.55. Found: C, 33.27; H, 3.51; N, 3.52. IR (cmꢀ1): ν(CdN) 1644 m,
1629 m. 1H NMR (300.1 MHz, DMSO-d6): δ 1.97 (s, 3 H, Me), 2.51 (s,
3 H, Me), 2.97 (m, 2 H, 1 H of CH2Ar + 1 H of CH2N), 3.20 (m, 1 H,
CH2), 3.83 (br s, 1 H, CH2), 6.70ꢀ6.90 (m, 3 H, H3 + H4 + H5), 7.29
(d, 1 H, H6, 3JHH = 7.5 Hz). 13C NMR (75.45 MHz, DMSO-d6): δ 22.2
(s, Me), 38.2 (br s, CH2Ar), 49.1 (s, CH2N), 124.1 (br s, CH, C6H4),
124.8 (br s, CH, C6H4), 125.7 (s, CH, C6H4), 139.7 (s, C, C6H4), 179.4
(s, CdN).
Synthesis of [Pd2(C,N-C6H4CH2CH2NHMe-2)2(μ-Cl)2] (1c-
Cl). The ammonium triflate C (800 mg, 2.804 mmol) was added to a
suspension of Pd(OAc)2 (629.5 mg, 2.804 mmol) in acetonitrile
(50 mL), and the resulting solution was heated at 60 °C for 2 h and
then at 78 °C for 2 h. The mixture was filtered through a plug of Celite/
Na2CO3, the solvent was removed from the filtrate, acetone (30 mL)
and NaCl (2000 mg, 34.22 mmol) were added, and the suspension was
stirred for 18 h. The solvent was removed, and CH2Cl2 (40 mL) was
added. The suspension was filtered through a plug of Celite, solvent was
removed from the filtrate, and the residue was vigorously stirred in Et2O
(15 mL) for 30 min. The suspension was filtered, and the solid was
washed with Et2O (2 ꢁ 5 mL) and air-dried to give complex 1c-Cl as a
pale orange solid. Yield: 510 mg, 0.924 mmol, 66%. Mp: 142 °C. Anal.
Calcd for C18H24Cl2N2Pd2 (552.142): C, 39.16; H, 4.38; N, 5.07.
Found: C, 38.81; H, 4.58; N, 5.36. IR (cmꢀ1): ν(NH) 3226 s. 1H NMR
(400.91 MHz, DMSO-d6): δ 1.68 (m, 1 H, CH2N), 2.32 (d, 3 H, Me,
3JHH = 5.2 Hz), 2.83 (m, 1 H, CH2Ar), 2.94 (m, 1 H, CH2Ar), 3.03 (m,
1 H, CH2N), 5.55 (br s, 1 H, NH), 6.84ꢀ7.10 (m, 3 H, H3 + H4 + H5),
7.43 (d, 1 H, H6, 3JHH = 7.6 Hz). 13C NMR (100.81 MHz, DMSO-d6): δ
40.5 (s, CH2Ar), 42.3 (s, Me), 49.6 (s, CH2N), 124.6 (s, CH, C4 or C5),
124.7 (s, CH, C4 or C5), 126.0 (s, CH, C3), 133.7 (s, CH, C6), 140.3 (s,
C2), 148.3 (br s, C1, CꢀPd).
Synthesis of [Pd(C,N-C6H4CH2CH2NH2-2)Cl(SPhos)] (3a-
Cl). SPhos (188 mg, 0.458 mmol) was added to a suspension of complex
1a-Cl (120 mg, 0.229 mmol) in CH2Cl2 (15 mL), and the resulting
solution was stirred for 30 min. The mixture was filtered through a plug
of MgSO4, solvent was removed from the filtrate, and the residue was
vigorously stirred in n-pentane (15 mL). The suspension was filtered,
and the solid was washed with n-pentane (2 ꢁ 1 mL) and air-dried to
give complex 3a-Cl as a pale yellow solid. Yield: 260 mg, 0.387 mmol,
85%. Mp: 176 °C dec. Anal. Calcd for C34H45ClNO2PPd (672.566): C,
60.72; H, 6.74; N, 2.08. Found: C, 60.43; H, 7.10; N, 2.17. IR (cmꢀ1):
Synthesis of [Pd2(C,N-C6H4CH2CH2NHMe-2)2(μ-Br)2] (1c-
Br). The ammonium triflate C (800 mg, 2.804 mmol) was added to a
suspension of Pd(OAc)2 (629.5 mg, 2.804 mmol) in acetonitrile
(50 mL), and the resulting solution was heated at 60 °C for 2 h and
then at 70 °C for 3 h. The mixture was filtered through a plug of Celite/
Na2CO3, the solvent was removed from the filtrate, acetone (30 mL)
and NaBr (1500 mg, 14.58 mmol) were added, and the suspension was
stirred for 18 h. The solvent was removed, and CH2Cl2 (40 mL) was
added. The suspension was filtered through a plug of Celite, solvent was
removed from the filtrate, and the residue was vigorously stirred in Et2O
(15 mL) for 30 min. The suspension was filtered, and the solid was
washed with Et2O (2 ꢁ 5 mL) and air-dried to give crude complex 1c-Br
as an orange solid. Yield: 714 mg, 1.114 mmol, 79%. Crude 1c-Br was
recrystallized from CH2Cl2/Et2O to give a spectroscopically pure sample
(recrystallization yield: 76%). IR (cmꢀ1): ν(NH) 3229. 1H NMR (300.10
MHz): δ 1.99 (m, 1 H, CH2N), 2.68 (d, 3 H, Me, 3JHH = 6.0 Hz), 2.98 (m,
2 H, 1 H of CH2Ar + 1 H of CH2N), 3.20 (m, 1 H, CH2Ar), 3.82 (br s,
1 H, NH), 6.78ꢀ6.86 (m, 2 H, H3+ H5), 6.93(t, 1 H, H4, 3JHH = 6.9Hz),
7.39 (br d, 1 H, H6, 3JHH = 6.0 Hz). Spectroscopic data are in accordance
with the data reported in the literature.14
1
ν(NH) 3323 m, 3245 m, 3214 m, 3137 m. H NMR (400.91 MHz,
CD2Cl2): δ 0.94 (br m, 2 H), 1.09 (br m, 4 H), 1.42 (br s, 2 H), 1.56 (br
m, 4 H), 1.72 (br s, 2 H), 1.89 (br s, 2 H), 2.03 (br s, 2 H), 2.20 (br m, 2
H), 2.71 (br s, 2 H), 3.13 (br m, 2 H), 3.17 (br s, 2 H), 3.69 (s, 6 H, Me),
6.40 (“t”, 1 H, 3JHH = 7.0 Hz), 6.66 (d, 2 H, 3JHH = 8.4 Hz), 6.69ꢀ6.77
(m, 2 H), 6.83 (dd, 2 H, 3JHH = 7.2, 4JHH = 1.6 Hz), 6.88 (br d, 1 H, 3JHH
=
6.8 Hz), 7.15ꢀ7.25 (m, 2 H), 7.37 (t, 1 H, 3JHH = 8.4 Hz). 31P NMR
(CD2Cl2, 162.29 MHz): δ 55.0 (br s). Spectroscopic data are in accor-
dance with the data reported in the literature.2
Synthesis of [Pd(C,N-C6H4CH2CH2NH2-2)Br(SPhos)] H2O
(3a-Br H2O). SPhos (160 mg, 0.390 mmol) was added to a suspension
3
3
of complex 1a-Br (120 mg, 0.196 mmol) in CH2Cl2 (15 mL), and the
resulting solution was stirred for 30 min. The mixture was filtered
through a plug of MgSO4, solvent was removed from the filtrate, and the
residue was vigorously stirred in n-pentane (15 mL). The suspension
was filtered, and the solid was washed with n-pentane (2 ꢁ 1 mL) and
air-dried to give complex 3a-Br H2O as a pale yellow solid. Yield: 240
3
Synthesis of [Pd2(C,N-C6H4CH2CH2NHMe-2)2(μ-I)2] (1c-I).
NaI (382 mg, 2.544 mmol) was added to a solution of 1c-Cl (140 mg,
0.254 mmol) in acetone (50 mL), and the suspension was stirred for 16
h. Solvent was removed, CH2Cl2 (40 mL) was added, and the resulting
suspension was filtered through a plug of Celite. The filtrate was
concentrated to ca. 2 mL, and Et2O (30 mL) was added. The suspension
mg, 0.326 mmol, 84%. Dec pt: 214 °C. Anal. Calcd for C34H45-
BrNO2PPd H2O (735.037): C, 55.56; H, 6.44; N, 1.91. Found: C,
3
55.57; H, 6.65; N, 2.12. IR (cmꢀ1): ν(NH) 3307 m, 3230 m, 3145 w.
1H NMR (400.91 MHz, CD2Cl2):δ0.95 (br m, 2 H), 1.09 (br m, 4 H), 1.41
(br s, 2 H), 1.56 (br m, 4 H), 1,56 (s, 2 H, H2O), 1.72 (br s, 2 H), 1.87 (br s,
2 H), 2.03 (br s, 2 H), 2.24 (br m, 2 H), 2.73 (br s, 2 H), 3.15 (br m, 4 H),
4629
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Organometallics
ARTICLE
3.70 (s, 6 H, Me), 6.42 (br t, 1 H, 3JHH = 6.8 Hz), 6.67 (d, 2 H, 3JHH
8.4 Hz), 6.67ꢀ6.74 (m, 2 H), 6.82ꢀ6.88 (m, 2 H), 7.14ꢀ7.24 (m 2 H),
7.39 (br t, 1 H, 3JHH = 8.4 Hz). 31P NMR (CD2Cl2, 162.29 MHz): δ 55.1
(br s).
=
complexes of Pd(II) containing ortho-metalated primary or
secondary phenethylamines, which react with phosphines to
render easily and economically Buchwald-type palladacycles.
Synthesis of (S)-[Pd{C,N-C6H4CH2CH(CO2Me)NH2-2}I-
(SPhos)] (3b-I). SPhos (120 mg, 0.292 mmol) was added to a solution
of complex 1b-I (120 mg, 0.146 mmol) in CH2Cl2 (20 mL), and the
resulting solution was stirred for 30 min. The mixture was filtered
through a plug of MgSO4, solvent was removed from the filtrate, and the
residue was vigorously stirred in n-pentane (15 mL). The suspension
was filtered, and the solid was washed with n-pentane (2 ꢁ 3 mL) and
air-dried to give complex 3b-I as an orange solid. Yield: 226 mg, 0.276
mmol, 94%. Mp: 169 °C. Anal. Calcd for C36H45INO4PPd (820.057):
C, 52.73; H, 5.53; N, 1.71. Found: C, 52.50; H, 5.89; N, 1.75. IR (cmꢀ1):
ν(NH) 3322 m, 3266 m; ν(CO) 1739 s. 1H NMR (400.91 MHz): δ 1.01
(br m, 4 H), 1.45ꢀ1.8 (br m, 11 H), 1.90 (br s, 2 H), 2.26 (br s, 3 H),
3.21 (d, 1 H, 2JHH = 12.8 Hz), 3.67 (s, 3 H, Me), 3.69 (s, 3 H, Me), 3.70
(s, 3 H, Me), 3.80 (br s, 2 H), 3.91 (br s, 2 H), 6.45 (br m, 1 H), 6.65 (t, 2
H, 3JHH = 7.6 Hz), 6.70 (m, 3 H), 6.85 (br s, 1 H), 6.93 (m, 1 H), 7.13 (br
s, 1 H), 7.19 (br m, 1 H), 7.37 (t, 1 H, 3JHH = 8.4 Hz). 31P NMR (162.29
’ ASSOCIATED CONTENT
S
Supporting Information. CIF files of the structures of
b
3b-I CHCl3 and 4. This material is available free of charge via the
Internet at http://pubs.acs.org.
3
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: jvs1@um.es (J.V.); ims@um.es (I.S.-L.).
’ ACKNOWLEDGMENT
We thank the Ministerio de Educaciꢀon y Ciencia (Spain),
FEDER (CTQ2007-60808/BQU), and Fundaciꢀon Sꢀeneca (04539/
GERM/06) for financial support. J.-A.G.-L. and M.-J. O.-M. are
grateful to the University of Murcia (Spain) and to the Ministerio
de Educaciꢀon y Ciencia (Spain), respectively, for their research
grants.
MHz): δ 57.8 (v br s). Single crystals of 3b-I CHCl3 suitable for an
3
X-ray diffraction study were obtained by slow diffusion of n-pentane into
a solution of 3b-I in CHCl3.
Synthesis of [Pd(C,N-C6H4CH2CH2NdCMe2-2)I(PPh3)] (4).
PPh3 (67 mg, 0.255 mmol) was added to a suspension of complex 2 (100
mg, 0.127 mmol) in CH2Cl2 (15 mL), and the resulting solution was
stirred for 1 h. The mixture was filtered through a plug of MgSO4,
solvent was removed from the filtrate, and the residue was vigorously
stirred in Et2O (15 mL) for 15 min. The suspension was filtered, and the
solid was washed with Et2O (2 ꢁ 1 mL) and air-dried to give complex 4
as a pale orange solid. Yield: 147 mg, 0.224 mmol, 88%. Mp: 207 °C dec.
Anal. Calcd for C29H29INPPd (655.836): C, 53.11; H, 4.46; N, 2.14.
Found: C, 53.14; H, 4.69; N, 2.21. IR (cmꢀ1): ν(CdN) 1659 m. 1H NMR
(400.91 MHz): δ 1.92 (s, 3 H, Me), 2.55 (br s, 3 H, Me), 2.99 (dd, 1 H,
CH2Ar, 2JHH = 13.4, 3JHH = 4.0 Hz), 3.08 (m, 1 H, CH2N), 3.80 (m, 1 H,
CH2N), 4.27 (td, 2JHH = 3JHH = 13.4, 3JHH = 6.4 Hz), 6.27ꢀ6.32 (m,
2 H, H4 + H6), 6.71 (td, 1 H, H5, 3JHH = 7.2, 4JHH = 2.0 Hz), 6.81 (d,
1 H, H3, 3JHH = 7.6 Hz), 7.25ꢀ7.30 (m, 6 H, m-H, PPh3), 7.33ꢀ7.38
(m, 3 H, p-H, PPh3), 7.53ꢀ7.58 (m, 6 H, o-H, PPh3). 13C NMR (100.81
MHz): δ 22.2 (d, Me, 4JCP = 5 Hz), 34.3 (s, Me), 39.1 (s, CH2Ar), 49.7
(s, CH2N), 123.3 (s, CH5, C6H4), 125.3 (s, CH3 + CH6, C6H4), 127.8
(d, m-CH, PPh3, 3JCP = 10.5 Hz), 130.0 (d, p-CH, PPh3, 4JCP = 1.9 Hz),
132.0 (d, i-C, PPh3, 1JCP = 50.1 Hz), 134.9 (d, o-CH, PPh3, 2JCP = 11.3
Hz), 134.9 (s, CH4, C6H4), 140.1 (s, C2, C6H4), 155.6 (s, C1, CꢀPd),
176.7 (s, CdN). 31P NMR (162.29 MHz): δ 33.9 (s). Single crystals
suitable for an X-ray diffraction study were obtained by slow diffusion of
n-pentane into a solution of 4 in CH2Cl2.
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flexible, and inexpensive synthesis of chloro, bromo, and iodo
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’ NOTE ADDED AFTER ASAP PUBLICATION
Reference 8 has been changed from the version of this citation
that was first posted on the web on July 28, 2011. The version of
reference 8 that appears as of August 17, 2011, is correct.
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