Facile synthesis of cyclometalated ruthenium complexes with substituted phenylpyridines

Article abstract of DOI:10.1002/ejic.200600359

We have developed a new strategy that uses the Kroehnke synthesis for the preparation of various substituted phenylpyridines in excellent yields (up to 88%). Starting with the appropriate commercially available acetophenone, a variety of phenylpyridines substituted by either electron-donating (i.e. methyl, methoxy) or -withdrawing groups (i.e. bromide, nitro) on the phenyl ring are obtained in a two-step synthesis. The corresponding functionalized cyclometalated ruthenium complexes can be prepared with unusually high yields by using methanol as reaction solvent. The electrochemical data of the complexes demonstrate the strong σ-donating character of the anionic phenylpyridine ligand. X-ray analyses of four complexes show a shortening of the Ru-C bond associated with the elongation of only one of the five Ru-N bonds (trans effect). Wiley-VCH Verlag GmbH & Co, KGaA, 2006.

Full text of DOI:10.1002/ejic.200600359

FULL PAPER
DOI: 10.1002/ejic.200600359
Facile Synthesis of Cyclometalated Ruthenium Complexes with Substituted
Phenylpyridines
Isabelle Sasaki,*[a] Laure Vendier,[a] Alix Sournia-Saquet,[a] and Pascal G. Lacroix[a]
Keywords: Metallacycles / N ligands / Ruthenium
We have developed a new strategy that uses the Kröhnke
synthesis for the preparation of various substituted phenyl-
pyridines in excellent yields (up to 88%). Starting with the
appropriate commercially available acetophenone, a variety
of phenylpyridines substituted by either electron-donating
(i.e. methyl, methoxy) or -withdrawing groups (i.e. bromide,
nitro) on the phenyl ring are obtained in a two-step synthesis.
The corresponding functionalized cyclometalated ruthenium
complexes can be prepared with unusually high yields by
using methanol as reaction solvent. The electrochemical data
of the complexes demonstrate the strong σ-donating charac-
ter of the anionic phenylpyridine ligand. X-ray analyses of
four complexes show a shortening of the Ru–C bond associ-
ated with the elongation of only one of the five Ru–N bonds
(trans effect).
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
Introduction
Results and Discussion
(Polypyridine)ruthenium() complexes have attracted
much interest as light absorbers, photoluminescent sensors
or switches, and intermolecular energy- and electron-trans-
fer agents.[1] Some cyclometalated counterparts of these
complexes have been prepared and their physical properties
reported.[2–6] In fact, cyclometalated complexes have found
widespread interest as species with promising properties in
various fields[7] owing to the strong σ-donor ability of the
cyclometalated ligand. Typically, the coordinating ligand
forms a bond to the metal center and then intramolecular
C–H activation takes place to yield a five-membered chelate
ring. Replacement of a nitrogen donor by a formal carban-
ion donor drastically increases the electron density around
the metal atom[4] and the crystal-field strength.[5]
Synthesis
Our synthetic route starts with the preparation of the
pyridinium derivative of the appropriate aromatic methyl
ketone.[14] Condensation of these derivatives with methacro-
lein gives the corresponding phenylpyridines, as described
in Scheme 1. We also checked this synthesis with tiglic alde-
hyde[16] to show that this methodology can be extended to
other α,β-unsaturated carbonyl compounds.
A variety of synthetic methodologies[8] for the synthesis
of new pyridine derivatives have been developed. One of
the most important is the transition-metal-catalyzed cross-
coupling reactions of precursors developed by Negishi, Su-
zuki, and Stille (see refs.[9–11]). In fact, all these methods
entail the preparation of functionalized intermediates.[12] In
the course of our studies we have prepared a number of
polypyridine ligands[13] by using the Kröhnke method.[14]
By extending this procedure to aromatic ketones, we pro-
pose an easy and versatile synthesis of substituted phenyl-
pyridines.[15] Starting from commercially available aceto-
phenones, a variety of mono- or difunctionalized phenyl-
pyridines substituted by electron-donating (i.e. methyl,
methoxy) or -withdrawing groups (i.e. bromide, nitro) on
the phenyl ring can be obtained with very good yields.
Scheme 1.
The different ligands synthesized in this work are sum-
marized together with the few previously reported mole-
cules in Table 1. To the best of our knowledge, no crystal
structure of a phenylpyridine has been published (vide
infra).
[a] Laboratoire de Chimie de Coordination, UPR 8241 du CNRS,
205 route de Narbonne, 31077 Toulouse Cedex 04, France
E-mail: sasaki@lcc-toulouse.fr
3294
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Cyclometalated Ruthenium Complexes with Substituted Phenylpyridines
Table 1. List and yields of ligands LH prepared by this method.
FULL PAPER
peaks corresponding to the phenylpyridine ring are influ-
enced by the electronic character of the substituents on the
phenyl ring. More precisely, in the high-field region between
δ = 7.3 and 5.9 ppm, the most high-field-shifted doublet is
assigned to the proton of the phenyl ring (8-H) in the ortho
position and its chemical shift varies from δ = 5.95 (meth-
oxy derivative 4h) to 7.3 ppm (nitro derivative 4f). The up-
field shift of the proton adjacent to the site of metalation
is a common feature of compounds of this type.[4,24,28] The
other shielded doublet (between δ = 6.45 and 7.05 ppm) is
attributed to the proton meta (9-H, complex 4a) or para
(10-H, complexes 4b, 4d, and 4h) to the metalated carbon
atom. An exception is observed for 4f, for which the proton
10-H is highly deshielded (δ = 7.69 ppm) due to the elec-
tron-withdrawing character of the nitro substituent.
Yield [%]
Ref.
[15,17,18]
[21]
3a:
R1 = R2 = R3 = H
88
84
88
62
82
77
79
81
76
R1 = R2 = H, R3 = CH3
R1 = CH3, R2 = R3 = H
R1 = Br, R2 = R3 = H
R1 = R3 = H, R2 = Br
R1 = NO2, R2 = R3 = H
R1 = R3 = H, R2 = NO2
R1 = OCH3, R2 = R3 = H
R1 = R3 = H, R2 = OCH3
[10]
3b:
3c:
3d:
3e:
3f:
3g:
3h:
[20]
[19,20]
The different products were obtained in good yields and
their characterizations were carried out by 1H and 13C
NMR spectroscopy as well as by mass spectrometry (FAB
or DCI) and microanalysis (see Experimental Section).
These compounds offer the possibility for further reactions
on both aromatic rings; for example, the Br atom on the
phenyl ring can be replaced in various reactions and the
NO2 group can be reduced, whereas the pyridine ring can
be functionalized thanks to the methyl group.[22]
X-ray Analysis
Single crystals of ligands 3a and 3b were obtained after
slow concentration of a mixture of pentane and ethyl ace-
tate. The ORTEP diagrams of 3a and 3b are shown in Fig-
ure 1.
The synthesis of five cyclometalated RuII complexes was
carried out by Constable’s method[4] with a modification
proposed by Coudret,[23] which uses only 5 equiv. of ligand
instead of a 15-fold excess.[4] We obtained much higher
yields of cyclometalated complexes (up to 90%) than ac-
cording to the literature procedure by using methanol in-
stead of dichloromethane[4] as solvent. Constable[24] has
studied the effect of different solvents in the reactions of
6-phenyl-2,2Ј-bipyridine with ruthenium(II) and concluded
that the higher the dielectric constant of the solvent the
greater the proportion of the metalated product formed (as
is the case with methanol compared to dichloromethane).
Purification of the complexes was carried out by column
chromatography, which enables recovery of the unreacted
excess of ligand. This synthesis yields the corresponding
functionalized ruthenium complexes directly, whereas in the
literature functionalization was carried out on the ruthe-
nium complexes. Using 3,5-dipyridylbenzene, Collin et al.
converted the corresponding cyclometalated complex into
the nitro derivative and subsequently into the amino deriva-
tive.[25] More recently, Coudret was able to obtain the corre-
sponding bromo-substituted complex upon treatment of
[Ru(bpy)2L]+ (L = phenpy) with NBS.[25] The synthesis of
the amino derivative was also carried out.[26] The different
Figure 1. X-ray molecular structures of 3a (top) and 3b (bottom).
Ligand 3a crystallizes in the P212121 orthorhombic space
direct functionalizations of the complex were possible only group. The two aromatic rings are not planar, with an N(1)–
at the position para to the carbanion.[27] In our case, by C(5)–C(6)–C(7) torsion angle of 32.3°. Ligand 3b crys-
using the appropriate starting material (acetophenone), tallizes in the P21/n monoclinic space group. The molecule
other positions of the substituent on the ligand and there- is slightly more planar than 3a, with an N(1)–C(5)–C(6)–
fore in the complex are accessible.
C(7) torsion angle of 28.4°. As these compounds are not
1
Complete assignment of the H and 13C NMR spectra symmetrical, and as the exact position of the substituents
of the complexes required 1D, 2D H-1H COSY, HMQC can be unambiguously determined by NMR spectroscopy
1
1
1H-13C and HMBC H-13C experiments. The labelling of and because of the synthetic scheme, the position of the
the atoms is that of the X-ray structures. For the five com- nitrogen atom is well defined. This is important for the
1
plexes, comparison of the H NMR spectra shows that the analysis of the X-ray data of the complexes.
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I. Sasaki, L. Vendier, A. Sournia-Saquet, P. G. Lacroix
FULL PAPER
Crystals of the four complexes 4bЈ, 4d, 4f, and 4h were angles of 3.00° and 0.27° in the bipyridine ligands with
obtained for X-ray analysis (Figure 2). In one case (4b), N(2)/N(3) and N(4)/N(5), respectively. Complex 4f crys-
good-quality crystals were available only after exchange of tallizes in the P21/n monoclinic space group, with one mole-
the trifluoromethanesulfonate counteranion by hexafluoro- cule in the asymmetric unit cell. The bipyridine ligands are
phosphate to give complex 4bЈ. Crystallization occurred nearly perfectly planar in the complex, with torsion angles
upon slow diffusion of diethyl ether into acetonitrile solu- of 0.30° and 0.40° for the bipyridine ligands with N(2)/N(3)
tions of the complexes at 5 °C.
and N(4)/N(5), respectively. By contrast, the torsion angle
The ruthenium complex 4bЈ crystallizes in the P21/n mo- in the phenylpyridine ligand is 1.63°. Complex 4h crys-
¯
noclinic space group. The asymmetric unit cell contains one tallizes in the P1 triclinic space group. The asymmetric unit
–
–
ruthenium complex, one PF6 anion, and one molecule of cell contains one ruthenium complex, one CF3SO3 anion,
acetone. The phenylpyridine ligand is almost perfectly and one molecule of acetonitrile. The phenylpyridine ligand
planar in the complex, with an N(1)–C(5)–C(6)–C(7) tor- is perfectly planar (torsion angle of 0.17°), whereas the bi-
sion angle of 0.59° against torsion angles of 2.69° and 1.73° pyridine ligands are slightly distorted, with torsion angles
in the bipyridine ligands with N(2)/N(3) and N(4)/N(5), of 5.96° and 4.46° for the bipyridine ligands with N(2)/N(3)
respectively. The brominated complex 4d crystallizes in the and N(4)/N(5), respectively.
C2/c monoclinic space group. The unit cell contains eight
The Cambridge Crystallographic Database contains 156
molecules of complex (Z = 8), and four molecules of water. entries with a (phenylpyridine)metal unit, most of them
The phenylpyridine ligand is roughly planar, with an N(1)– containing platinum (55) and palladium (24). However,
C(5)–C(6)–C(7) torsion angle of 2.95° against torsion structures containing a (bpy)2(phenpy)metal unit are far
Figure 2. ORTEP representation of the X-ray structureS of 4bЈ (top left), 4d (top right), 4f (bottom left), and 4h (bottom right). The
hydrogen atoms, solvent molecules, and counteranions are omitted for clarity.
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Cyclometalated Ruthenium Complexes with Substituted Phenylpyridines
FULL PAPER
Table 2. First coordination sphere (metal–ligand bond lengths [Å]) in [RuII(bpy)2(L)]+ complexes.
Complex
Ru(1)–C(7)
Ru(1)–N(1)
Ru(1)–N(2)
Ru(1)–N(3)
Ru(1)–N(4)
Ru(1)–N(5)
4bЈ
2.036(3)
2.030(5)
2.020(4)
2.031(8)
2.029(5)
1.997(7)
2.044(1)
2.080(2)
2.071(4)
2.078(4)
2.067(6)
2.074(4)
2.075(5)
2.069(4)
2.043(2)
2.042(4)
2.047(4)
2.047(5)
2.045(4)
2.040(5)
2.067
2.036(2)
2.051(4)
2.055(4)
2.042(6)
2.046(4)
2.056(5)
2.046
2.066(2)
2.065(4)
2.060(4)
2.066(6)
2.064(4)
2.086(5)
2.037
2.138(2)
2.123(4)
2.121(4)
2.121(6)
2.125(4)
2.140(5)
2.075
4d
4f
4h
Av. value
a[a]
b[a]
[a] a: [Ru(bpy)2(NPP)][BF4][6] [NPP = 2-(3-nitrophenyl)pyridine]. b: [Ru(bpy)2(ppy)][PF6][28] (ppy = phenylpyridine).
less common, with only four entries.[6,29–31] In two of them,
namely [Ru(bpy)2(phenpy)][CrMn(ox)3][30] and [Rh(bpy)2-
(phenpy)](PF6),[31] the localization of the carbon atom was
not possible. In the third complex, [Ru(bpy)2(phen-
py)](PF6),[29] the carbon atom was arbitrarily localized be-
cause its distribution was equal on the six atomic sites
bonded to the Ru atom. Finally, the only crystal structure
in which the carbon–metal bond was unambiguously iden-
tified is that of [RuII(bpy)2{2-(nitrophenyl)pyridine}](BF4),
reported by Reveco et al.[6] The description of the coordina-
tion sphere of the four new complexes 4bЈ, 4d, 4f, and 4h is
compared to the previously reported structures in Table 2.
First of all, it must be pointed out that the position of the
carbon atom is unambiguous as the positions of the substit-
uents in the unsymmetrical ligands are definite. The average
metal–ligand distances for the four available structures were
calculated and show the following general features: (1)
whereas the Ru(1)–C(7) bond is shorter than the other
metal–ligand bonds, the Ru–N bonds to both the nitrogen
atom trans to the carbon atom [N(5)] and the one cis to the
carbon atom [N(1)] are slightly elongated, which leads to a
distorted octahedral geometry around the metal atom; (2)
the Ru(1)–N(4) bond is also slightly elongated, but less than
Ru(1)–N(5), probably because it belongs to the same bipyri-
dine ligand; (3) the Ru(1)–N(2) and Ru(1)–N(3) bond
lengths have similar values, thus showing that this bipyri-
dine ligand is the least disturbed by the cyclometalating li-
gand. Interestingly, comparison of the Ru(1)–C(7) bond
length [1.997(7) Å] in [RuII(bpy)2{2-(3-nitrophenyl)-
pyridine}](BF4)[6] and that in complex 4f [2.020(4) Å, the
smallest value in the series of complexes 4], in which the
nitro substituent is at the 4-position, demonstrates the influ-
ence of the electron-withdrawing character of the substitu-
ent. More precisely, in the para position, both inductive and
mesomeric effects are transmitted to C(9) whereas in the
meta position (complex 4f) only an inductive effect is in
operation.
Figure 3. Cyclic voltammograms at room temperature of ruthe-
nium complexes 4c, 4d, 4f, 4h (solid line) and ligands 3c, 3d, 3f, 3h
(dashed line) in CH3CN with 0.1  TBABF4 as supporting electro-
lyte (Pt electrode, v = 0.1 Vs–1).
Ligands 3c, 3d, and 3h exhibit two processes: one in oxi-
dation (ca. 1.9 V) and one in reduction (ca. –2.4 V). How-
ever, ligand 3h presents another oxidation (1.55 V) due to
the methoxy substituent. Ligand 3f displays two reduction
processes: a reversible redox couple at –1 V assigned to the
NO2 substituent and an irreversible reduction at –1.84 V
(much higher than those of other ligands). This suggests
that because of the electron-withdrawing properties of the
NO2 group, the oxidation is also dramatically shifted to
higher potentials that are not measurable under the experi-
mental conditions.
Cyclic voltammetry of the complexes exhibits three char-
acteristic processes: one oxidation process and two re-
duction processes.
Electrochemistry
The ligands and ruthenium complexes were examined by
First, the reversible redox couple at around 0.5 V is read-
cyclic voltammetry (Figure 3) and Osteryoung square-wave ily assigned to the RuIII/RuII process.[4,32] A comparison of
voltammetry (Table 3).
the potentials in Table 3 indicates that the first metal-cen-
Eur. J. Inorg. Chem. 2006, 3294–3302
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I. Sasaki, L. Vendier, A. Sournia-Saquet, P. G. Lacroix
FULL PAPER
Table 3. Redox potentials ([V] vs. SCE) of the ligands and ruthe- these compounds could lead to various polynuclear com-
plexes[34] or to new compounds with potential NLO proper-
nium complexes in 0.1  TBABF4 in acetonitrile solutions mea-
sured at room temperature.
ties.[22]
Oxidation
Reduction
[a]
[b]
[b]
[a]
[a]
[a]
[b]
E1/2
E1/2
E1/2
E1/2
E1/2
E1/2
E1/2
3c
1.90
1.91
–2.44
–2.19
–1.84
–2.55
Experimental Section
3d
3f
n.d.[c] –1.04
General: Reagents and solvents were commercially available and
were used as received. [Ru(bpy)2Cl2] was prepared according to a
literature procedure.[35] 1H and 13C NMR spectra were obtained at
298 K in CDCl3, CD3COCD3, or (CD3)2SO with a Bruker AM 250
3h
1.55 1.99
1.73
4c
0.48
0.60
0.67
–1.54 –1.82 –2.40
–1.51 –1.76 –2.24
4d
1.77
4f
1.99 –1.12 –1.57 –1.81 –1.94
1
spectrometer (250 MHz for H NMR and 62.9 MHz for 13C) or a
4h
0.52 1.63 n.d.[c]
1.29
–1.53 –1.79 –2.37
–1.35 –1.54 –1.73
[33]
Bruker Avance 500 spectrometer for 2D NMR. DCI and EI mass
spectra were recorded with a Thermo Finnigan TSQ 7000 and FAB
mass spectra were recorded with a quadrupolar Nermag R 10-10
instrument with NBA as matrix. Elemental analyses were per-
formed at the LCC with a Perkin–Elmer 2400 Serie II instrument.
Electrochemistry data: Voltammetric measurements were carried
out with a potentiostat Autolab PGSTAT 100. A home-made, air-
tight three-electrode cell connected to a vacuum/argon line made
up of a Pt disk (0.5 mm diameter) as working electrode, a Pt gauze
as auxiliary electrode, and an SCE as reference electrode. All ex-
periments were performed at ambient temperature in CH3CN solu-
tion, with 0.1  nBu4NBF4 as supporting electrolyte (purum elec-
trochemical grade Fluka, purified by sublimation). The solutions
used for the electrochemical studies were typically 10–3  in ruthe-
nium complex. Prior to measurements, the solutions were deoxy-
genated by bubbling with argon gas for 15 min and the working
Ru(bpy)3
[a] The E1/2 values were estimated as the average of the cathodic
and anodic peak potentials in cyclic voltammetry with a scan rate
of 100 mVs–1. [b] The E1/2 values were obtained from the square-
wave voltammogram: frequency 20 Hz, step potential 5 mV, ampli-
tude 20 mV. [c] Not observed or badly defined under the experi-
mental conditions.
tered oxidation of the complex is shifted by about 800 mV
to more cathodic potentials than that of [Ru(bpy)3].[33] This
behavior demonstrates the strong σ-donating character of
the phenylpyridine ligands, which stabilize RuIII by increas-
ing the electron density on the metal atom.[4,7c] Moreover,
the nature of the substituents affects the shift of the RuIII
/
RuII potential. The methyl and methoxy substituents with electrode was polished with a polishing machine (Presi P230); dur-
ing experiments, a stream of argon was passed over the solution.
All potentials are reported vs. SCE.
electron-donating character induce the most significant
shift, whereas the electron-withdrawing groups (Br and
NO2), which decrease the electron density on RuIII, lower
the magnitude of the shift.
X-ray Analysis: Data collection (Table 4) was performed at low
temperature (180 K) with an IPDS STOE diffractometer equipped
with a graphite-monochromated Mo-Kα radiation source (λ =
0.71073 Å) and an Oxford Cryosystems Cryostream Cooler Device.
The final unit-cell parameters were obtained by means of a least-
squares refinement performed on a set of 5000 well-measured re-
flections. Crystal decay was monitored during the data collection;
no significant fluctuations of intensities were observed. The struc-
tures were solved by direct methods using SIR92,[36] and refined by
means of least-squares procedures on F2 with the aid of the pro-
gram SHELXL97[37] included in the software package WinGX ver-
sion 1.63.[38] Atomic scattering factors were taken from the Inter-
national Tables for X-ray Crystallography.[39] All hydrogen atoms
were located geometrically and refined by using a riding model. All
non-hydrogen atoms were refined anisotropically, and in the last
cycles of refinement a weighting scheme was used, where weights
are calculated from the following formula: w = 1/[σ2(Fo2)+
Second, the complexes exhibit two reduction processes at
around –1.55 and –1.80 V (–1.35 and –1.54 V for [Ru(bpy)3]).
Complex 4f displays an additional first reduction pro-
cess at –1.12 V assigned to the NO2 substituent. Generally,
compared to [Ru(bpy)3], the bpy-centered quasi-reversible
reductions are shifted to more negative potentials and are
also strongly affected by the presence of the cyclometallat-
ing ligand,[7c] but the nature of the substituents does not
affect significantly these processes. Moreover, the most
cathodic potentials near the solvent/electrolyte limit were
resolved in the square-wave experiment and were assigned
to the phenylpyridine ligand.
2
(aP)2 +bP] where P = (Fo2 +2Fc )/3. Drawings of the molecules
Conclusions
were produced with the program ORTEP32,[40] with 30% prob-
ability displacement ellipsoids for non-hydrogen atoms. CCDC-
603013 to -603018 contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
We have been able to synthesize new substituted phenyl-
pyridines in high yields by a very simple general method
from cheap, commercially available starting materials.
Functionalized cyclometalated ruthenium(II) complexes
were obtained in much higher yields than the few examples
described in the literature. As crystals for four of them were
obtained, an X-ray study highlighted specific features of the
Ru–C and the trans-Ru–N bonds. The easiness in obtaining
first the ligands and then the cyclometalated complexes is
a breakthrough for the application of these complexes. By a
Typical Procedure for the Preparation of the Pyridinium Derivatives
2a–h: A solution of sublimated iodine (5.25 g, 20.5 mmol) in 8 mL
of dry pyridine was added to a solution of 20 mmol of acetophe-
none in 5 mL of dry pyridine. After heating at 80 °C for 6 h, then
cooling, the precipitate was filtered off, rinsed once with pyridine,
dried, and recrystallized from boiling ethanol. The corresponding
“building block” approach, involving convergent synthesis, pyridinium derivative was isolated as a beige powder.
3298 Eur. J. Inorg. Chem. 2006, 3294–3302
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Cyclometalated Ruthenium Complexes with Substituted Phenylpyridines
Table 4. Crystal data, data collection and refinements parameters for ligands 3a and 3b and complexes 4bЈ, 4d, 4f, and 4h.
FULL PAPER
3a
3b
4bЈ
4d
4f
4h
Empirical formula
Formula mass
Crystal size [mm]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C12H11
169.22
N
C13H13
183.24
0.35×0.25×0.12
monoclinic
P21/n
6.338(5)
7.218(5)
22.561(15)
90
96.211(5)
90
1026.1(11)
1.186
180
0.069
φ
N
C36H34F6N5OPRu
798.72
0.375×0.11×0.05
monoclinic
P21/n
9.0328(7)
13.7518(10)
27.824(2)
90
87.981(10)
90
3454.1(4)
1.536
180
0.570
φ
C33H26BrF3N503.5Ru C35H30F3N6O5.5RuS
C37H31F3N6O4RuS
801.80
0.3×0.2×0.08
triclinic
¯
P1
9.240(5)
13.611(5)
15.545(5)
66.107(5)
83.613(5)
72.623(5)
1705.8(12)
1.561
818.63
0.4×0.2×0.07
monoclinic
C2/c
812.78
0.5×0.3×0.07
orthorhombic
P212121
6.1173(5)
7.4700(5)
20.0874(19)
90
0.45×0.1875×0.05
monoclinic
P21/n
24.295(5)
13.694(3)
20.137(4)
90
15.2172(16)
14.5676(10)
16.8313(17)
90
90
90
105.74(3)
90
112.241(11)
90
γ [°]
V [Å3]
917.92(13)
1.224
180
0.072
φ
6449(3)
1.686
3453.5(6)
1.563
ρcalcd. [gcm–3
T [K]
]
180
180
180
0.587
φ
µ(Mo-Kα) [mm–1
Scan mode
]
1.853
0.584
φ
φ
Measured reflec-
tions
7932
7840
32316
27761
29682
15476
Independent reflec- 1075
tions
1950
1950
6770
6770
5432
5432
5882
5882
5659
5659
Observed reflec-
tions
1075
Criteria
IϾ2σ(I)
F2
119
calculated
0.0285
0.0705
0.125
–0.111
1.052
IϾ2σ(I)
F2
129
calculated
0.0504
0.1312
0.208
–0.228
1.053
IϾ2σ(I)
F2
455
calculated
0.0319
0.0706
0.551
–0.480
0.974
IϾ2σ(I)
F2
430
calculated
0.0504
0.1407
1.192
–1.043
1.033
IϾ2σ(I)
F2
453
calculated
0.0456
0.1001
0.558
–0.410
0.884
IϾ2σ(I)
F2
463
calculated
0.0744
0.1716
1.049
–1.529
0.910
Refinement on
No of parameters
H atoms
R1
wR2
∆ρmax [eÅ–3
]
]
∆ρmin [eÅ–3
GOF
Compound 2a: Yield: 4.03 g (62%). 1H NMR ([D6]DMSO): δ = Compound 2e: Yield: 5.55 g (75%). 1H NMR ([D6]DMSO): δ =
9.01 (d, J = 5.5 Hz, 2 H), 8.75 (dt, J = 7.9 and 1.2 Hz, 1 H), 8.29
(t, J = 7.4 Hz, 2 H), 8.07 (dd, J = 7 and 1.4 Hz, 2 H), 7.79 (m, 1
H), 7.67 (dt, J = 7.6 and 1.7 Hz, 2 H), 6.51 (s, 2 H) ppm. 13C NMR
([D6]DMSO): δ = 190.6, 146.4, 146.2, 134.7, 133.4, 129.1, 128.2,
127.8, 66.3 ppm. C13H12INO (325.14): calcd. C 48.02, H 3.72, N
4.31; found C 47.92, H 3.38, N 4.09. FAB-MS: m/z = 198 [M–I]+.
8.98 (d, J = 5.7 Hz, 2 H), 8.76 (m, 2 H), 8.63 (dd, J = 8.2 and
2 Hz, 1 H), 8.48 (d, J = 7.8 Hz, 1 H), 8.31 (dd, J = 7.1 and 7 Hz,
2 H), 7.98 (t, J = 8 Hz, 1 H), 6.55 (s, 2 H) ppm. 13C NMR ([D6]-
DMSO): δ = 189.6, 148.0, 146.6, 146.2, 134.8, 134.3, 131.0, 128.6,
127.9, 122.5, 66.3 ppm. C13H11IN2O3 (370.14): calcd. C 42.18, H
3.00, N 7.57; found C 42.22, H 2.92, N 7.45. FAB-MS: m/z = 243
[M–I]+.
Compound 2b: Yield: 4.27 g (63%). 1H NMR ([D6]DMSO): δ =
8.98 (d, J = 5.5 Hz, 2 H), 8.71 (t, J = 7.8 Hz, 1 H), 8.24 (dd, J =
7.3 and 6.6 Hz, 2 H), 7.86 (s, 1 H), 7.84 (d, J = 6.3 Hz, 1 H), 7.54
(m, 2 H), 6.44 (s, 2 H), 2.44 (s, 3 H) ppm. 13C NMR ([D6]DMSO):
δ = 190.6, 146.3, 146.2, 138.5, 135.3, 133.5, 129.0, 128.4, 127.8,
Compound 2f: Yield: 5.33 g (72%). 1H NMR ([D6]DMSO): δ = 8.97
(d, J = 5.5 Hz, 2 H), 8.76 (t, J = 7.8 Hz, 1 H), 8.48 (d, J = 8.8 Hz,
2 H), 8.27–8.32 (m, 4 H), 6.51 (s, 2 H) ppm. 13C NMR ([D6]-
DMSO): δ = 190.0, 146.4, 146.2, 132.5, 132.2, 130.1, 128.8, 127.8,
125.5, 66.2, 20.8 ppm. C14H14INO (339.17): calcd. C 49.58, H 4.16, 66.1 ppm. C13H11IN2O3 (370.14): calcd. C 42.18, H 3.00, N 7.57;
N 4.13; found C 49.58, H 4.27, N 4.00. FAB-MS: m/z = 212
found C 42.33, H 2.95, N 7.46. FAB-MS: m/z = 243 [M–I]+.
Compound 2g: Yield: 5.82 g (82%). 1H NMR ([D6]DMSO): δ =
[M–I]+.
Compound 2c: Yield: 6.30 g (78%). 1H NMR ([D6]DMSO): δ = 8.99 (d, J = 5.5 Hz, 2 H), 8.75 (t, J = 7.8 Hz, 1 H), 8.29 (dd, J =
8.97 (d, J = 5.5 Hz, 2 H), 8.76 (t, J = 7.8 Hz, 1 H), 8.30 (dd, J =
7.2 and 6.8 Hz, 2 H), 8.22 (m, 1 H), 8.1–8.0 (m, 2 H), 7.65 (t, J =
7.9 Hz, 1 H), 6.48 (s, 2 H) ppm. 13C NMR ([D6]DMSO): δ = 189.8,
7.5 and 6.6 Hz, 2 H), 7.70–7.55 (m, 2 H), 7.54 (s, 1 H), 7.39 (md,
J = 7.7 Hz, 1 H), 6.48 (s, 2 H), 3.87 (s, 3 H) ppm. 13C NMR ([D6]-
DMSO): δ = 190.4, 159.4, 146.3, 146.2, 134.7, 130.3, 127.8, 120.6,
146.5, 146.2, 137.1, 135.5, 131.4, 130.7, 127.9, 127.2, 122.3, 120.4, 112.7, 66.3, 55.5 ppm. C14H14INO2 (355.17): calcd. C 47.34,
66.2 ppm. C13H11BrINO (404.04): calcd. C 38.65, H 2.74, N 3.47;
H 3.97, N 3.94; found C 47.39, H 3.97, N 4.00. FAB-MS: m/z =
found C 38.71, H 2.55, N 3.33. FAB-MS: m/z = 277 [M–I]+.
228 [M–I]+.
Compound 2d: Yield: 6.30 g (78%). 1H NMR ([D6]DMSO): δ = Compound 2h: Yield: 5.11 g (72%). 1H NMR ([D6]DMSO): δ =
8.97 (d, J = 5.5 Hz, 2 H), 8.74 (t, J = 7.8 Hz, 1 H), 8.28 (dd, J = 9.00 (d, J = 5.5 Hz, 2 H), 8.74 (t, J = 7.8 Hz, 1 H), 8.27 (dd, J =
7.1 and 7 Hz, 2 H), 8.00 (d, J = 8.6 Hz, 2 H), 7.90 (d, J = 8.6 Hz, 7.5 and 6.7 Hz, 2 H), 8.05 (d, J = 8.8 Hz, 2 H), 7.19 (d, J = 8.8 Hz,
2 H), 6.45 (s, 2 H) ppm. 13C NMR ([D6]DMSO): δ = 190.0, 146.4,
146.2, 132.5, 132.2, 130.1, 128.8, 127.8, 66.1 ppm. C13H11BrINO
(404.04): calcd. C 38.65, H 2.74, N 3.47; found C 38.55, H 2.50, N
3.24. FAB-MS: m/z = 277 [M–I]+.
2 H), 6.45 (s, 2 H), 3.90 (s, 3 H) ppm. 13C NMR ([D6]DMSO): δ
= 188.8, 164.2, 146.2, 130.7, 127.7, 126.2, 114.4, 66.9, 55.8 ppm.
C14H14INO2 (355.17): calcd. C 47.34, H 3.97, N 3.94; found C
47.22, H 3.60, N 3.72. FAB-MS: m/z = 228 [M–I]+.
Eur. J. Inorg. Chem. 2006, 3294–3302
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3299

I. Sasaki, L. Vendier, A. Sournia-Saquet, P. G. Lacroix
FULL PAPER
Typical Procedure for the Preparation of the Phenylpyridines 3a–h:
NH4OAc (4 equiv., 8 mmol) and methacrolein (4 mmol) were
added to a solution of the pyridinium derivative (2 mmol) in 5 mL
of formamide. The reaction mixture was heated at 80 °C for 6 h
and, after cooling, the ligand precipitated and was filtered off and
rinsed with water. If the ligand did not precipitate it was extracted
with Et2O (3×20 mL), the organic phase was dried with MgSO4,
concentrated to dryness, and purified by chromatography on silica
gel with EtOAc in pentane (10:90) or methanol in dichloromethane
(3:97) as eluent.
6.97 (dd, J = 8.8 and 1.8 Hz, 2 H), 3.86 (s, 3 H), 2.34 (s, 3 H) ppm.
13C NMR (CDCl3): δ = 160.1, 154.3, 149.8, 137.2, 133.0, 130.8,
127.8, 119.2, 114.0, 55.2, 18.0 ppm. C13H13NO (199.25): calcd. C
78.39, H 6.53, N 7.03; found C 78.30, H 6.59, N 6.96. DCI-MS:
m/z = 200 [MH]+.
General Procedure for the Preparation of the Complexes: [Ru(bpy)2-
Cl2] (0.15 mmol) and AgOTf (0.30 mmol) were added to a solution
of the ligand (0.75 mmol) in 5 mL of MeOH, and the mixture was
refluxed in the dark for 2 h. After cooling and filtration of a brown
precipitate, the filtrate was concentrated off and purification was
carried out by chromatography on alumina. Elution with EtOAc/
pentane (10:90) provided unreacted ligand and further elution with
MeOH/CH2Cl2 (3:97) gave the pure complex.
1
5-Methyl-2-phenylpyridine (3a): H NMR (CDCl3): δ = 8.51 (d, J
= 1.2 Hz, 1 H), 7.96 (m, 2 H), 7.62 (d, J = 8 Hz, 1 H), 7.54 (dd, J
= 8 and 2.1 Hz, 1 H), 7.49–7.35 (m, 3 H), 2.36 (s, 3 H) ppm. 13C
NMR ([D6]DMSO): δ = 154.7, 150.0, 139.3, 137.4, 131.6, 128.7,
128.6, 126.7, 120.0, 18.2 ppm. C12H11N(169.23): calcd. C 85.21, H
6.51, N 8.28; found C 85.29, H 6.37, N 8.21. DCI-MS: m/z = 170
[MH]+.
5-Methyl-2-(3-methylphenyl)pyridine (3b): 1H NMR (CDCl3): δ =
8.51 (s, 1 H), 7.79 (s, 1 H), 7.71 (d, J = 7.5 Hz, 1 H), 7.61 (d, J =
8 Hz, 1 H), 7.53 (dd, J = 8.1 and 1.9 Hz, 1 H), 7.34 (t, J = 7.6 Hz,
1 H), 7.19 (d, J = 7.5 Hz, 1 H), 2.42 (s, 3 H), 2.35 (s, 3 H) ppm.
13C NMR (CDCl3): δ = 154.9, 150.0, 139.3, 138.3, 137.3, 131.5,
128.6, 127.4, 123.8, 120.1, 21.5, 18.1 ppm. C13H13N (183.25): calcd.
C 85.21, H 6.51, N 8.28; found C 85.29, H 6.37, N 8.21. DCI-MS:
m/z = 184 [MH]+.
2-(3-Bromophenyl)-5-methylpyridine (3c): 1H NMR (CDCl3): δ =
8.51 (s, 1 H), 7.87 (td, J = 7.8 and 1.5 Hz, 1 H), 7.58 (m, 2 H),
7.50 (ddd, J = 8, 1.7 and 0.8 Hz, 1 H), 7.32 (t, J = 8 Hz, 1 H), 2.38
(s, 3 H) ppm. 13C NMR (CDCl3): δ = 152.9, 150.1, 141.3, 137.4,
132.3, 131.4, 130.2, 129.7, 125.1, 123.0, 120.0, 18.2 ppm.
C12H10BrN (248.12): calcd. C 58.09, H 4.06, N 5.65; found C 58.15,
H 3.74, N 5.52. DCI-MS: m/z (%) = 248 (96), 250 (100) [MH]+.
2-(4-Bromophenyl)-5-methylpyridine (3d): 1H NMR (CDCl3): δ =
8.49 (d, J = 0.6 Hz, 1 H), 7.83 (m, 2 H), 7.58 (m, 4 H), 2.35 (s, 3
H) ppm. 13C NMR (CDCl3): δ = 153.5, 150.1, 138.2, 137.5, 132.0,
131.8, 128.2, 123.0, 119.8, 18.2 ppm. C12H10BrN (248.12): calcd. C
58.09, H 4.06, N 5.65; found C 58.14, H 3.93, N 5.59. DCI-MS:
m/z (%) = 248 (100), 250 (95) [MH]+.
5-Methyl-2-(3-nitrophenyl)pyridine (3e): 1H NMR (CDCl3): δ =
8.81 (s, 1 H), 8.54 (s, 1 H), 8.33 (d, J = 7.7 Hz, 1 H), 8.22 (dd, J =
8 and 1.1 Hz, 1 H), 7.70 (d, J = 8 Hz, 1 H), 7.62 (m, 2 H), 2.40 (s,
3 H) ppm. 13C NMR (CDCl3): δ = 152.0, 150.4, 148.7, 141.0, 137.7,
133.1, 132.5, 129.6, 123.2, 122.5, 120.1, 18.2 ppm. C12H10N2O2
(214.22): calcd. C 67.28, H 4.70, N 13.08; found C 67.13, H 4.44,
N 12.97. DCI-MS: m/z = 215 [MH]+.
5-Methyl-2-(4-nitrophenyl)pyridine (3f): 1H NMR (CDCl3): δ = 8.57
(s, 1 H), 8.31 (d, J = 8.9 Hz, 2 H), 8.15 (d, J = 8.9 Hz, 2 H), 7.71
(d, J = 8.1 Hz, 1 H), 7.62 (dd, J = 8.1 and 1.8 Hz, 1 H), 2.41 (s, 3
H) ppm. 13C NMR (CDCl3): δ = 152.0, 150.4, 148.7, 141.0, 137.7,
133.1, 132.5, 129.6, 123.2, 122.5, 120.1, 18.2 ppm. C12H10N2O2
(214.22): calcd. C 67.28, H 4.70, N 13.08; found C 67.41, H 4.34,
N 12.95. DCI-MS: m/z = 215 [MH]+.
2-(3-Methoxyphenyl)-5-methylpyridine (3g): 1H NMR (CDCl3): δ =
8.51 (d, J = 1.5 Hz, 1 H), 7.60 (t, J = 8 Hz, 1 H), 7.55 (m, 2 H),
7.36 (t, J = 8 Hz, 1 H), 6.93 (dd, J = 8.2 and 2.5 Hz, 1 H), 3.88 (s,
3 H), 2.36 (s, 3 H) ppm. 13C NMR (CDCl3): δ = 160.0, 154.5,
150.0, 140.9, 137.3, 131.7, 129.6, 120.1, 119.1, 114.7, 111.7, 55.3,
18.2 ppm. C13H13NO (199.25): calcd. C 78.39, H 6.53, N 7.03;
found C 78.08, H 6.60, N 6.83. DCI-MS: m/z = 200 [MH]+.
Complex 4a: Yield: 98 mg (90%). 1H NMR (CD3COCD3): δ = 8.77
(dt, J = 8.2 and 1 Hz, 1 H, H25), 8.68 (dt, J = 8 and 1.1 Hz, 1 H,
H28), 8.61 (dt, J = 8 and 1 Hz, 1 H, H18), 8.59 (dt, J = 8 and
1 Hz, 1 H, H15), 8.16 (ddd, J = 5.7, 1.5 and 0.7 Hz, 1 H, H31),
8.13 (ddd, J = 9.2, 5.6 and 1.5 Hz, 1 H, H24), 8.06 (d, J = 8.3 Hz,
1 H, H4), 8.05 (m, 1 H, H22), 7.98–7.93 (m, 3 H, H12, H29, H19),
7.92–7.86 (m, 3 H, H11, H14, H21), 7.62 (ddd, J = 8.7, 2.1 and
0.7 Hz, 1 H, H3), 7.59 (ddd, J = 7.5, 5.4 and 1.2 Hz, 1 H, H23),
7.56 (m, 1 H, H1), 7.39–7.34 (m, 3 H, H20, H30, H13), 6.88 (dd,
J = 7.2 and 1.3 Hz, 1 H, H10), 6.81 (td, J = 7.3 and 1.3 Hz, 1 H,
H9), 6.18 (ddd, J = 7.3, 1.3 and 0.4 Hz, 1 H, H8), 2.08 (s, 3 H,
CH3py) ppm. 13C NMR (CD3COCD3): δ = 191.79 (C7), 164.97
(C5), 157.88 (C27), 157.15 (C17), 156.81 (C16), 155.36 (C26),
154.15 (C31), 150.24 (C29), 149.98 (C11), 149.77 (C1), 149.10
(C22), 145.57 (C6), 136.73 (C3), 136.41 (C24), 135.18 (C8), 134.98
(C29), 133.78 (C19), 133.53 (C14), 132.07 (C2), 128.10 (C9), 127.22
(C23), 126.48 (C20), 126.29 (C30), 126.14 (C13), 123.73 (C11),
123.58 (C28), 123.34 (C25), 123.06 (C15), 123.04 (C18), 120.74
(C10), 118.39 (C4), 17.15 (CH3py) ppm. FAB-MS: m/z = 582 [M–
OTf]+.
Complex 4b: Yield: 98 mg (88%). Metathesis: the complex with the
triflate counterion was dissolved in the minimum amount of meth-
anol, then a saturated solution of NH4PF6 was added until no more
precipitation was observed. The precipitate was filtered off, rinsed
with distilled water, and dried under vacuum. 1H NMR ([D6]-
DMSO): δ = 8.76 (d, J = 8.2 Hz, 1 H, H25), 8.68 (d, J = 8.2 Hz,
1 H, H28), 8.61 (d, J = 8.8 Hz, 1 H, H15), 8.59 (d, J = 8.8 Hz, 1
H, H18), 8.09 (td, J = 7.5 and 0.9 Hz, 1 H, H24), 8.04 (d, J =
8.3 Hz, 1 H, H4), 7.99 (d, J = 5.4 Hz, 1 H, H31), 7.91 (t, J =
8.1 Hz, 1 H, H29), 7.89 (t, J = 8 Hz, 1 H, H19), 7.86 (t, J = 8.1 Hz,
1 H, H14), 7.81 (d, J = 5.3 Hz, 1 H, H22), 7.72 (d, J = 5.6 Hz, 1
H, H12), 7.68 (s, 1 H, H11), 7.62 (d, J = 5.6 Hz, 1 H, H21), 7.58
(d, J = 8.8 Hz, 1 H, H3), 7.56 (t, J = 6.5 Hz, 1 H, H23), 7.38 (t, J
= 6.5 Hz, 1 H, H30), 7.36 (m, 1 H, H20), 7.35 (t, J = 7 Hz, 1 H,
H13), 7.28 (s, 1 H, H1), 6.61 (d, J = 7.4 Hz, 1 H, H9), 6.18 (d, J
= 7.5 Hz, 1 H, H8), 2.22 (s, 3 H, CH3phe), 2.04 (s, 3 H, CH3py)
ppm. 13C NMR ([D6]DMSO): δ = 187.54 (C7), 164.74 (C5), 157.72
(C27), 157.0 (C16), 156.65 (C17), 155.22 (C26), 153.91 (C31),
150.03 (C21 or C12), 149.78 (C12 or C21), 149.55 (C1), 148.99
(C22), 145.55 (C10), 137.21 (C3), 136.86 (C24), 135.45 (C29),
134.94 (C8), 134.20 (C14 or C19), 133.89 (C19 or C14), 132.14
(C2), 129.78 (C9), 129.33 (C6), 127.83 (C23), 127.05 (C20 or C13),
126.87 (C13 or C20), 126.77 (C30), 124.99 (C11), 124.21 (C28),
123.94 (C25), 123.69 (C15), 123.64 (C18), 118.86 (C4), 21.27
(CH3ph), 18.17 (CH3py) ppm. FAB-MS: m/z = 596 [M–PF6]+.
Complex 4d: Yield: 90 mg (74%). 1H NMR (CD3COCD3): δ = 8.78
(dt, J = 8.2 and 1 Hz, 1 H, H25), 8.71 (dt, J = 8.1 and 1 Hz, 1 H,
2-(4-Methoxyphenyl)-5-methylpyridine (3h): 1H NMR (CDCl3): δ = 1 H, H28), 8.64 (dt, J = 8.3 and 1 Hz, 1 H, H15), 8.62 (dt, J = 8.3
8.47 (s, 1 H), 7.90 (dd, J = 8.7 and 1.6 Hz, 2 H), 7.6–7.5 (m, 2 H),
and 1 Hz, 1 H, H18), 8.17 (ddd, J = 5.7, 1.7 and 0.7 Hz, 1 H, H31),
3300
www.eurjic.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 3294–3302

Cyclometalated Ruthenium Complexes with Substituted Phenylpyridines
FULL PAPER
V. Balzani, F. Barigelletti, L. De Cola, L. Flamigni, Chem. Rev.
1994, 94, 993–1019.
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8.14 (td, J = 8.4 and 1.5 Hz, 1 H, H24), 8.09 (d, J = 8.2 Hz, 1 H,
H4), 8.02 (ddd, J = 5.4, 1.6 and 0.8 Hz, 1 H, H22), 8.00 (ddd, J =
7.6, 5 and 0.5 Hz, 1 H, H29), 7.98 (ddd, J = 7.6, 5 and 0.5 Hz, 1
H, H14), 7.95 (m, 1 H, H19), 7.93 (m, 1 H, H21), 7.88 (ddd, J =
5.7, 1.4 and 0.8 Hz, 1 H, H12), 7.82 (d, J = 8.3 Hz, 1 H, H11), 7.64
(ddd, J = 8.3, 1.1 and 0.7 Hz, 1 H, H3), 7.59 (ddd, J = 7.5, 5.4 and
0.8 Hz, 1 H, H23), 7.57 (d, J = 1.2 Hz, 1 H, H1), 7.44–7.37 (m, 2
H, H30, H20), 7.42 (dd, J = 5.8 and 1.5 Hz, 1 H, H13), 7.04 (dd,
[2]
[3]
[4]
[5]
J = 8.3 and 2.1 Hz, 1 H, H10), 6.54 (d, J = 2.1 Hz, 1 H, H8), 2.08
(s, 3 H, CH3) ppm. 13C NMR (CD3COCD3): δ = 196.20 (C7),
[6]
163.95 (C5), 157.77 (C27), 157.07 (C16), 156.74 (C17), 155.32
(C26), 154.18 (C31), 150.39 (C21), 150.12 (C12), 149.98 (C1),
149.17 (C22), 144.86 (C6), 137.02 (C8), 136.93 (C3), 136.70 (C24),
135.38 (C29), 134.32 (C14), 134.20 (C19), 132.68 (C2), 127.27
(C23), 126.73 (C30), 126.55 (C20), 126.37 (C13), 125.32 (C11),
123.73 (C28), 123.67 (C9), 123.54 (C10), 123.45 (C25), 123.27
(C18), 123.25 (C15), 118.77 (C4), 17.19 (CH3) ppm. FAB-MS: m/z
(%) = 662 (45), 660 (43) [M–OTf]+.
[7]
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S. Kotha, K. Lahiri, D. Kashinath, Tetrahedron 2002, 58, 9633–
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[8]
[9]
[10]
Complex 4f: Yield: 28 mg (24%). 1H NMR (CD3COCD3): δ = 8.81
(d, J = 8.2 Hz, 1 H, H25), 8.73 (d, J = 8.1 Hz, 1 H, H28), 8.67 (d,
J = 8 Hz, 1 H, H15), 8.63 (d, J = 8 Hz, 1 H, H18), 8.28 (d, J =
8.2 Hz, 1 H, H4), 8.17 (td, J = 7.9 and 1.6 Hz, 1 H, H24), 8.11 (d,
J = 8.6 Hz, 1 H, H11), 8.12 (m, 1 H, H31), 8.06 (ddd, J = 5.3, 1.4
and 0.8 Hz, 1 H, H22), 8.03 (td, J = 7.7 and 1.4 Hz, 1 H, H14),
7.98 (td, J = 8 and 1.5 Hz, 1 H, H29), 7.96 (m, 1 H, H19), 7.94
(m, 1 H, H21), 7.92 (m, 1 H, H12), 7.74 (m, 1 H, H3), 7.72 (m, 1
H, H1), 7.69 (dd, J = 8.5 and 2.4 Hz, 1 H, H10), 7.62 (ddd, J =
7.5, 5.5 and 1.2 Hz, 1 H, H23), 7.46 (ddd, J = 7.3, 5.7 and 1.3 Hz,
1 H, H13), 7.39 (ddd, J = 7.3, 5.7 and 1.3 Hz, 2 H, H30, H20),
7.29 (d, J = 2.4 Hz, 1 H, H8), 2.13 (s, 3 H, CH3) ppm. 13C NMR
(CD3COCD3): δ = 194.80 (C7), 162.76 (C5), 157.78 (C26), 157.03
(C16), 156.75 (C17), 155.30 (C26), 154.34 (C22), 152.86 (C6),
150.60 (C1), 150.47 (C21), 150.24 (C12), 149.25 (C22), 146.99 (C9),
137.12 (C3), 136.89 (C24), 135.61 (C29), 134.73 (C14), 134.57
(C19), 134.44 (C2), 128.41 (C8), 127.33 (C23), 126.93 (C13), 126.67
(C30 or C20), 126.52 (C20 or C30), 123.83 (C28), 123.65 (C11),
123.54 (C25), 123.43 (C15), 123.39 (C18), 120.39 (C4), 115.90
(C10), 17.31 (CH3) ppm. FAB-MS: m/z = 627 [M–OTf]+.
[11]
[12]
[13]
[14]
[15]
V. Bonnet, F. Mongin, F. Trécourt, G. Quéguiner, P. Knochel,
Tetrahedron 2002, 58, 4429–4438.
[16]
The reaction of 2a with (E)-2-methyl-2-butenal (tiglic aldehyde)
was carried out under the same conditions and led to 4,5-di-
methyl-2-phenylpyridine in 84% yield.[21] 1H NMR (CDCl3): δ
= 8.39 (s, 1 H), 7.94 (dd, J = 6.8 and 1.5 Hz, 2 H), 7.48–7.36
(m, 4 H), 2.32 (s, 3 H), 2.27 (s, 3 H) ppm. 13C NMR (CDCl3):
δ = 155.1, 149.9, 146.2, 139.5, 130.7, 128.7, 128.4, 126.7, 121.4,
19.4, 16.1 ppm. C13H13N+0.05OHCNH2 (185.50): calcd. C
84.50, H 7.14, N 7.93; found C 84.38, H 6.72, N 7.48. DCI-
MS: m/z = 183 [M]+.
[17]
[18]
[19]
R. F. Francis, C. D. Crews, B. S. Scott, J. Org. Chem. 1978, 43,
3227–3239.
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Verbouwe, F. C. De Schryver, J. Chem. Soc., Perkin Trans. 2
2002, 928–937.
Complex 4h: Yield: 95 mg (83%). 1H NMR (CD3COCD3): δ = 8.77
(d, J = 8.2 Hz, 1 H, H25), 8.72 (d, J = 8.2 Hz, 1 H, H28), 8.62 (d,
J = 8.1 Hz, 1 H, H18), 8.60 (d, J = 8.1 Hz, 1 H, H15), 8.20 (dd, J
= 5.8 and 1.1 Hz, 1 H, H31), 8.12 (td, J = 7.8 and 1.5 Hz, 1 H,
H24), 8.05 (dd, J = 5.4 and 1.3 Hz, 1 H, H22), 7.97 (m, 1 H, H29),
7.95 (m, 1 H, H12), 7.94 (m, 1 H, H21), 7.92 (d, J = 8.2 Hz, 1 H,
H4), 7.89 (m, 1 H, H19), 7.88 (m, 1 H, H14), 7.82 (d, J = 8.5 Hz,
1 H, H11), 7.58 (ddd, J = 7.5, 5.4 and 1.1 Hz, 1 H, H23), 7.55 (dd,
J = 8.4 and 2.1 Hz, 1 H, H3), 7.47 (m, 1 H, H1), 7.39–7.34 (m, 3
H, H13, H20, H30), 6.45 (dd, J = 8.5 and 2.6 Hz, 1 H, H10), 5.95
(d, J = 2.4 Hz, 1 H, H8), 3.53 (s, 3 H, OCH3), 2.04 (s, 3 H, CH3)
ppm. 13C NMR (CD3COCD3): δ = 194.27 (C7), 164.71 (C5),
159.59 (C6), 157.84 (C27), 157.29 (C17), 156.83 (C16), 155.36
(C26), 154.06 (C31), 150.22 (C29), 150.03 (C14), 149.41 (C1),
149.11 (C22), 138.37 (C9), 136.65 (C3), 136.41 (C24), 134.99 (C12),
133.78 (C21), 133.59 (C19), 130.77 (C2), 127.19 (C23), 126.43
(C20), 126.27 (C30), 126.12 (C13), 124.99 (C11), 123.64 (C28),
123.42 (C25), 123.13 (C15), 123.07 (C18), 119.69 (C8), 117.63 (C4),
106.43 (C10), 53.73 (OCH3), 17.10 (CH3) ppm. FAB-MS: m/z =
612 [M–OTf]+.
[20]
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