Cycloruthenated complexes from imine-based heterocycles: Synthesis, characterization, and reactivity toward alkynes

Article abstract of DOI:10.1002/chem.201201382

Novel cycloruthenated complexes 2 a-c, 4 a-c, and 6 a, b based on heteroaromatic cores have been synthesized by reaction of a series of heterocycle-based imines with [{RuCl(e⁶-p-cymene)} ₂(μ-Cl)₂] and Cu(OAc)₂.

Full text of DOI:10.1002/chem.201201382

FULL PAPER
DOI: 10.1002/chem.201201382
Cycloruthenated Complexes from Imine-Based Heterocycles: Synthesis,
Characterization, and Reactivity toward Alkynes
Luciano Cuesta,[a] Tatiana Soler,[b] and Esteban P. Urriolabeitia*[a]
Abstract: Novel cycloruthenated com-
plexes 2a–c, 4a–c, and 6a,b based on
heteroaromatic cores have been syn-
thesized by reaction of a series of het-
erocycle-based imines with [{RuCl(h6-
À
cles react with 3-hexyne through an un-
expected pathway, which involves the
coupling of the original imino hetero-
cycle and acetylene followed by dearo-
matization to afford fused hetero-hy-
dropyridyl ligands bonded to the {Ru-
ACHTUNGTRNE(NUNG p-cymene)} organometallic moiety
(i.e., 7a–c and 8a–c). These complexes
represent, as far as we know, the first
examples of this type of compound
within the context of cyclometalation,
and an exhaustive analysis of their
structure was carried out in solution
and solid state. Furthermore, these
unique species react with CuCl2, which
promotes the rearomatization and the
release of highly valuable aromatic
fused bis-heterocycles (i.e., 9a–c, 10a–
p-cymene)}2ACHTUNGTRENNUNG(m Cl)2] and CuACHTUNGTRENN(UGN OAc)2.
This approach has proved efficient for
the cyclometalation of thiophene, ben-
zothiophene, furan, benzofuran, pyr-
role, and indole derivatives. In addi-
tion, even a double cyclometalation
process over the same heterocyclic ring
is possible, yielding unprecedented bi-
metallic complexes. These ruthenacy-
c, 11a, and 12a/12a’), providing
a
novel and appealing synthetic route to
this extraordinary family of molecules.
Keywords: alkynes · annulation ·
cyclometalation · dearomatization ·
heteroarenes · ruthenium
Introduction
Among all the transformations that can be performed by
means of cyclometalation-based methods, annulation reac-
tions have emerged as a very attractive synthetic tool to pro-
duce fused derivatives. Typically, this transformation is car-
The cyclometalation of ligands by transition metals is one of
the best developed areas of organometallic chemistry,
mainly because this strategy represents a mild route for acti-
À
ried out by coupling a C H activation step with a subse-
À
À
vating C H bonds selectively, thus displaying great synthetic
quent alkyne insertion into the cyclometalated M C bond.
potential.[1] This strategy has proved to be an extremely
useful and efficient tool for the functionalization of organic
substrates, thus allowing the selective incorporation of a
large variety of functional groups into a plethora of organic
molecules.[2] In contrast with the immense number of exam-
ples that deal with the cyclometalation of arenes, the use of
a directing group to achieve selective functionalization of ar-
omatic heterocycles has been much less exploited. Interest-
ingly, recent examples of heterocyclic functionalization by
cyclometalation, either stoichiometrically or catalytically,
have served to highlight the fact that this method is a viable
and attractive option.[3]
This type of transformation has attracted considerable atten-
tion due to practical synthetic utility and theoretical interest
and has been widely exploited with arene derivatives.[1d,l,2f,4]
Recently, this transformation has also emerged as an attrac-
tive way to functionalize heteroarenes, thus allowing the
synthesis of highly valuable “fused” bis-heterocyclic com-
pounds, such as b- and g-carbolines,[5] b- and g-carboli-
nones,[6] or heterocyclic analogues of isocoumarins.[7]
On the other hand, fused derivatives of pyridine have at-
tracted considerable interest because of their great practical
usefulness, which is primarily due to their various biological
activities.[8] Among these compounds, species containing a
bi-heterocyclic core (such as indolo-, pyrrolo-, benzofuro-,
furo-, benzothieno-, and thienopyridines) occupy a special
place and have attracted tremendous interest because of
their extraordinary pharmacological activities.[9] For in-
stance, this unique family of molecules has been the base
for analgesics, analeptics, antiarrhythmics, anticancer agents,
antihypersensitives, antiseptics, antidepressants, tranquilizing
agents, antipsychotics, spasmolytics, neuroleptics, and drugs
with other pharmacological activities. Not surprisingly, due
to the importance of this type of compound, there are sever-
al reported procedures for the preparation of these bicyclic
and tricyclic species.[10] However, as far as we know, there is
not a general method to obtain all of them in a systematic
[a] Dr. L. Cuesta, Dr. E. P. Urriolabeitia
Departamento de Activaciꢀn de enlaces por complejos metꢁlicos
Instituto de Sꢂntesis Quꢂmica y Catꢁlisis Homogꢃnea
CSIC-Universidad de Zaragoza
Pedro Cerbuna 12, 50009 Zaragoza (Spain)
Fax : (+34)976761187
E-mail: esteban@unizar.es
[b] Dr. T. Soler
Servicios Tꢃcnicos de Investigaciꢀn
Facultad de Ciencias, Universidad de Alicante
03690 San Vicente de Raspeig, Alicante (Spain)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201201382.
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way. We envisioned that these derivatives could be pro-
duced by the aforementioned strategy based on the cou-
pling of heterocyclic substrates with alkynes through regio-
À
selective C H bond activation with the aid of imine moie-
ties as directing groups. In fact, we have recently exploited
this approach for the particular synthesis of several thieno-
ACHTUNGTRENNUNG[3,2-c]pyridines by employing thienyl-cyclopalladated com-
plexes.[11a]
Scheme 1. Synthesis of complexes 2a–c.
We have now extended our studies to other complexes
containing different heteroarenes. In particular, we have
found a general and efficient way to cyclometalate aromatic
À
KOAc, and CuACHTNUGTRENUNG(OAc)2) under different conditions (solvents,
temperatures), and the reactions between imines 1a–c,
heterocycles by employing [{RuCl(h6-p-cymene)}
(m Cl)2]
À
and Cu
A
[{RuCl(h6-p-cymene)}
G
G
cloruthenated complexes toward 3-hexyne. During the
course of these studies, we found the formation of unexpect-
ed intermediary organometallic entities. Oxidation with
CuCl2 of these fascinating species afforded bi-heterocyclic
compounds containing thieno-, benzothieno-, furo-, benzo-
808C over 24 h afforded straightforwardly the targeted com-
plexes containing cycloruthenathed thiophene, furan, or pyr-
role rings in moderate-to-good yields (Scheme 1). The use
of toluene was crucial because no product was formed in
solvents such as methanol or acetonitrile, and poor yields
furo-, and pyrrolo
G
were observed in dichloroethane. The use of CuACTHUNGTERNNU(G OAc)2 was
pyrido[3,4-b]indolium unit.
G
also essential for the success of the reactions because only
traces of the complexes were detected when NaOAc or
KOAc were used in toluene. This latter observation proba-
bly is a consequence of the much higher solubility of the
copper salt in toluene, although we cannot discard the possi-
bility that the copper plays another role.
Results and Discussion
Synthesis of the cycloruthenated complexes: Recently, we
described the cyclometalation of thiophenes and benzothio-
phenes by using imines as directing groups and Pd[11a] or
The cyclometalated nature of the new complexes 2a–c
1
was initially inferred from the H NMR spectroscopic data,
Ru[11b] complexes to promote C H activation. However, not
in which the disappearance of one of the b-heterocyclic pro-
tons in the starting materials 1a–c was observed; conse-
quently, the expected AB systems for the remaining two
heterocyclic protons were observed. Also, the signal patterns
observed for the p-cymene ligands are indicative of the pres-
ence of a stereogenic center, as expected for the structures
depicted in Scheme 1 for complexes 2a–c. In the
13C{1H} NMR spectrum there are significantly deshielded
signals (d=197.5, 176.0, and 175.5 ppm for 2a–c, respective-
ly), which are attributed to the s-carbon atoms bonded to
the metallic center. The structures were confirmed by mass-
spectrometry and elemental analysis, and, in the case of
complex 2a, which contains a thiophene ring, the solid-state
structure was studied by means of X-ray diffraction meth-
ods.
À
all the metalation reactions show the same scope. The palla-
dation reaction was limited to substrates with the imine
group in the b position, therefore producing the C H bond
activation at the reactive a position. In the case of the sub-
strate with the a-imine group, it coordinates as a N,S-chelate
and precludes further reactivity. Interestingly, the cycloru-
thenation reaction was carried out irrespective of the imine
location, and activation at both the a and b positions takes
À
À
place. The occurrence of C H bond activation instead of
N,S-chelation is similar to the so-called “rollover” metala-
tion of bipyridine and related compounds reported for other
metals.[12] As far as we know, there are very few examples of
rollover metalation in ruthenium.[12d] Moreover, the strat-
egies described[11] proved ineffective for the cyclometalation
of other heterocycles, such as furan or pyrrole. Recently,
several examples have been reported that describe the bene-
ficial effects of combining metalating agents with acetate li-
The corresponding benzannulated derivatives 4a–c were
straightforwardly synthesized by using the same approach
(Scheme 2). These species were fully characterized by
means of NMR spectroscopy, mass-spectrometry, and ele-
mental analysis. The loss of the b-heterocyclic protons and
gands,[13] in which the C H bond metalation is believed to
À
be facilitated by base assistance and increased electrophilici-
ty of the metal center. There-
fore, by aiming to expand our
studies to other imine-based
heterocycles, we tried the “roll-
over” cyclometalation of li-
gands 1a–c by cooperation of
the acetate and ruthenium spe-
cies.
We tested several sources of
the acetate ion (i.e., NaOAc, Scheme 2. Synthesis of complexes 4a–c.
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Cycloruthenation of Heterocycles through Directed C H Bond Activation
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Figure 1. Top view of complexes 2a and 4b with a full atom-labeling scheme. Left: 2a, right: 4b. Thermal ellipsoids are scaled to the 50% probability
level. The hydrogen atoms have been removed for clarity.
the signals expected for a p-cymene ligand bound to a
stereo
genic metal were clearly observed in the 1H NMR
spectra. Accordingly, the presence of s-carbon atoms
bonded to the ruthenium center was inferred by the observ-
ance of considerably deshielded signals in the attached
proton test (APT) spectra.
equivalent systems can be cyclometalated at the a but not
the b position under identical conditions.[17] This observation
can be attributed to the higher reactivity of the a versus the
b position of five-membered heterocycles, which is more
manifest in the case of furan due to its low aromaticity.[18]
All the described complexes display the ruthenium as a
ACHTUNGTRENNUNG
In addition, the structures of the thiophene- and benzofur-
an-based complexes 2a and 4b, respectively, were deter-
mined in the solid state by means of X-ray diffraction meth-
ods. The crystal structure of complex 2a is shown in
Figure 1 (left). The Ru atom lies in the classical pseudo-oc-
tahedral “piano-stool” environment, in which the p-cymene
stereo
chiral sources, we assumed that 2a–c and 4a–c are obtained
as racemic mixtures.
ACHTUNGTRENgNGNU enic center; however, due to absence of additional
AHCTUNGTRENNUNG
The synthetic strategy described above can be easily ex-
panded for the synthesis of complexes that result from an
unprecedented double cycloruthenation process of the same
heterocyclic ring. Accordingly, the reactions between the
Schiff bases 5a,b, containing two imine moieties, with equi-
À
À
À
ligand is the stool and the legs are the Ru C Ru N, and
À
À
Ru Cl bonds. The Ru C(3) bond length of 2.041(2) ꢅ falls
in the range observed for other ruthenacycles containing cy-
molar amounts of the complex [{RuCl(h6-p-cymene)}
2ACHTUNGTRENNUNG(m
clometalated
thiophene
ligands
(i.e.,
1.950(9)–
Cl)2] and an excess of CuACTHNGUTRENUN(G OAc)2 in toluene at 1008C over
24 h furnished the new bimetallic complexes 6a,b
(Scheme 3). Both thiophene and furan derivatives undergo
2.114(4) ꢅ).[14] The molecular structure of complex 4b
(Figure 1, right) displays a very similar structure to that de-
scribed for 2a, with the Ru atom in a pseudo-octahedral
À
the double C H activation under these conditions. Howev-
À
“piano-stool” environment. The Ru C(9) bond length is
er, attempts to synthesize the analogous pyrrole-based com-
pound 5c systematically failed. As far as we know, this type
of process, in which the same heterocyclic ring (thienyl or
2.051(8) ꢅ, comparable to the equivalent distance in 2a
À
(2.041(2) ꢅ) and slightly shorter than the Ru C bond length
À
(2.092(5) ꢅ) observed in the only previous example of a
benzofuran-based cycloruthen-
ated complex characterized by
X-ray diffraction methods.[15]
furyl) undergoes two C H activations, was unknown up to
This method is remarkably
versatile as the five-membered
heterocycles 1a–c and their
benzanulated derivatives 3a–c
can be straightforwardly cyclo-
metalated at the b position by
À
direct C H activation, including
the furane derivative 1b. This
À
fact is noteworthy because C H
activation centered at the b po-
sition of furane is a challenging
task, and examples of this type
of metalation are scarce.[16] In
fact, there are cases in which Scheme 3. Synthesis and dynamic behavior of complexes 6a,b.
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E. P. Urriolabeitia et al.
now with ruthenium or any other metal. Obviously, this fact
opens a new door to the polyfunctionalization of the same
heterocyclic core at different positions, which is a difficult
task when conventional synthetic pathways are employed.
The characterization of complexes 6a,b was carried out
by using a combination of NMR spectroscopy, mass-spec-
trometry, and elemental analysis. The 1H NMR spectra of
these species clearly indicated the absence of thienyl or
furyl protons and confirmed the presence of stereogenic
metallic centers as judged by the pattern of signals of the p-
cymene moieties. In the room-temperature 1H NMR spectra,
some of the protons of the p-cymene ligands displayed
severe broadening (see the Supporting Information). Low-
Figure 2. Side view of complex 6a with a partial atom-labeling scheme.
The hydrogen atoms have been removed for clarity.
1
temperature H NMR spectroscopic experiments carried out
with 6a (see the Supporting Information) allowed the detec-
tion of the presence of two different species, one of them
clearly as a major component. A 2D EXSY NMR spectro-
scopic experiment performed at 263 K (see the Supporting
Information) revealed that both species were in a dynamic
equilibrium.
These results evidence the efficiency of the method,
which is applicable not only to all the five-membered
heteroACHTNUTRGNEaNUG renes and their benzannulated derivatives, but also
allows the synthesis of unprecedented double cyclometalat-
ed thiophene or furane complexes.
Our proposed rationale to explain this observation is out-
lined in Scheme 3. We believe that the two sets of signals
for 6a correspond to geometric isomers with the p-cymene
ligands in transoid and cisoid orientations, with the transoid
isomer as the major compound because this species situates
the arene ligands at opposite sides of the plane defined by
the heterocycle and the metal centers, thus minimizing steric
interactions.[19] Although several possibilities exist, the most
plausible way to interconvert the transoid and cisoid isomers
dynamically is the dissociation of the halide ligand, the for-
mation of a 16eÀ planar transition state, and the re-coordi-
nation of the halide ligand at the other side of the molecular
plane. This mechanism has been extensively studied,[19a] and
it has been shown that the presence of strong s-donor li-
gands, such as the C,N-cyclometalated ligands, favor the for-
mation of 16eÀ planar intermediates. Therefore, this result
Reactivity toward 3-hexyne: An unexpected reaction path-
way: In our aim to develop a simple and general method to
produce bis-heterocyclic fused derivatives of pyridine, we
tested the reaction between the cycloruthenated complexes
described above (i.e, 2a–c and 4a–c) with alkynes. In partic-
ular, we disclose herein the results obtained with 3-hexyne.
The reaction between complexes 2a–c or 4a–c and 3-hexyne
in methanol in the presence of KPF6 afforded the new com-
plexes 7a–c and 8a–c, respectively (Scheme 4). The yields of
these reactions are close to quantitative, and analysis of the
reaction crude products revealed a complete transformation
of the complexes 2a–c or 4a–c into the new species without
the formation of any other byproducts, irrespective of the
nature of the heterocycle. Monitoring the reaction by
1H NMR spectroscopic methods revealed that the reaction
time was strongly dependent on the nature of the heterocy-
cle. The pyrrole derivative reacted considerably faster than
the thiophene or furane derivatives (4, 14, and 16 h, respec-
tively), and the benzannulated analogues always required
longer reaction times (20, 30, and 6 h for benzothiophene,
benzofurane, and indole, respectively). Although the reasons
remain speculative in absence of kinetic data, it is sensible
to propose that the reaction rate is related to the electron
density of the heteroarene. Thus, the pyrrole derivative,
which contains the heterocycle richest in electron density, is
the fastest reacting and the furan derivative is slightly
slower than the thiophene derivative, according to their dif-
ferent electronic properties. These results are in very good
agreement with those previously reported by Pfeffer and co-
workers,[20] which showed that electron-rich arenes react
faster with alkynes than electron-deficient rings.[20b] More-
over, the degree of aromaticity of the metalated heterocycle
can also be related to the rate of insertion because lower ar-
À
indicates that probably the Ru Cl bond is being broken and
reformed in this type of complex. In the case of 6b, with a
furan core instead of thiophene, we presume a similar be-
havior; however, the 1H NMR spectrum of the expected
mixture of isomers could not be resolved, even at low tem-
peratures (see the Supporting Information). The same type
of fast transoid/cisoid equilibrium has been observed in re-
lated species.[19b–d]
Further structural information was gained from X-ray dif-
fraction analysis of a crystal of 6a. A drawing of the molecu-
lar structure of 6a is shown in Figure 2. Although the data
obtained were of modest quality and are not amenable for a
discussion of the distances and angles, they clearly con-
firmed the connectivity inferred from the NMR spectroscop-
ic data for the major species, assigned to the transoid
isomer. In this complex, two ruthenium “piano-stool” moie-
ACHTUNGTRENNUNGties are supported by just one thienyl ligand, showing that a
À
double metalation process over a single heterocyclic ring
has taken place. As expected, the transoid conformation ar-
ranges the p-cymene ligands as far as possible, thus minimiz-
ing the steric interactions.
omaticity results in a stronger Ru C bond, and hence in a
less-reactive species toward alkyne insertion. In all cases,
the fusion of the benzene ring seems to decrease the reactiv-
ity of the heterocyclic rings in these reactions.
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Cycloruthenation of Heterocycles through Directed C H Bond Activation
FULL PAPER
these products as depicted in
Scheme 4, in which the Ru
atom is in an oxidation state of
two and the new heterocyclic
ligand is coordinated to the
metal center by a combination
of s and p interactions.
X-ray structural analysis of
7a and 8c were carried out to
elucidate the nature of these
compounds fully, thus confirm-
ing the proposed connectivity.
Drawings of the X-ray struc-
tures of both complexes show
that 7a and 8c (Figure 3, left
and right, respectively) are
mononuclear cationic com-
plexes with a sandwich struc-
ture in which the ruthenium
center is h6-bound to the p-
cymene ring by p coordination.
Scheme 4. Reactions between complexes 2a–c or 4a–c and 3-hexyne.
The basic skeleton of struc-
tures 7a–c and 8a–c was initial-
ly inferred from the NMR spec-
troscopic data. For instance, the
analysis of the 1H NMR spec-
troscopic data of 7a revealed
that the insertion of one acety-
lene unit has taken place, as
judged by the presence of two
nonequivalent ethyl groups, and
the presence of one p-cymene
ligand embedded into an asym-
metric environment was also
evident. Pfeffer and co-workers
studied the reactivity of cyclo-
Figure 3. Side view of complexes 7a and 8c. Left: 7a, right: 8c. Thermal ellipsoids are scaled to the 50% prob-
ability level. The hydrogen atoms and PF6 counteranions have been removed for clarity. Selected bond lengths
[ꢅ] of 7a: N(1)–C(1) 1.4771(2), C(1)–C(2) 1.4249(2), C(2)–C(3) 1.4464(2), C(3)–C(6) 1.4274(2), C(6)–C(7)
1.4133(2), C(7)–N(1) 1.4339(2), Ru–C(1) 2.1888(3), Ru–C(2) 2.1828(2), Ru–C(3) 2.2450(3), Ru–C(6) 2.1710(3),
Ru–C(7) 2.1156(2).
ruthenated complexes with in-
ternal alkynes in considerable
detail.[20] This strategy proved
to be highly efficient for the
synthesis of isoquinolinium de-
rivatives. In these studies, the
authors detected intermediate species with a sandwich struc-
ture involving h6-coordination of an arene and h4-coordina-
tion of the cationic heterocycle to a Ru0 atom.[20a,c] The for-
mation of similar structures can be expected in our reac-
tions; however, in the 13C NMR spectrum of 7a, the signal
assigned to the carbon atom bound to the initially iminic ni-
trogen atom appears at d=38.5 ppm and the hydrogen atom
bonded to this carbon atom appears at d=5.76 ppm in the
1H NMR spectrum. Similar features were observed for all
the compounds (i.e., 7b,c and 8a–c). These data suggest
that in our system, the carbon atom bound to the nitrogen
atom is now a sp3 carbon atom; therefore, the ring generat-
ed by the coupling of the imine and alkyne groups is not ar-
omatic, thus leading us to tentatively assign structures for
Concerning the bonding mode of the new heterocycle
formed, it can be considered to be an intermediate point be-
tween h5- and h1:h2:h2- or h1:h4-coordination modes. In both
of the complexes, the nitrogen atom is not involved in the
bonding, as is clear from the structures in Figure 3.
Analysis of the bond lengths involved in the ruthenium
À
center of complex 7a indicates that the bond length Ru
C(7) (2.1156(2) ꢅ) is the shortest, as expected due to the
important s component of this bond. Accordingly, the rest
À
of the Ru C bond lengths involved in the heterocyclic core
are significantly longer (2.1888(3)–2.2450(3) ꢅ) and can be
considered typically to be p interactions. Interestingly, the
À
average of the Ru C bond lengths implicated with the p-
cymene ligand are significantly longer (2.2088(3)–
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E. P. Urriolabeitia et al.
1
2.3155(2) ꢅ) than those bonds that involved p interactions
with the new heterocyclic ring, which is probably a conse-
quence of the anionic nature of the latter. A comparison of
of the p-cymene ligands in both the H and 13C NMR spec-
tra were not observed, thus confirming the loss of the metal-
lic fragment. The most significant signals in the 1H NMR
spectra of 9a–c and 10a–c are the singlet signals at around
d=8.5–9.0 ppm, attributed to the proton situated into the
pyridinium ring. This observation, together with the appear-
ance of the carbon atoms assigned to the C=N unit in the ar-
omatic region of the 13C NMR spectra, indicate that the pyr-
idinium ligand has regained aromaticity. When the workup
involving chromatography was omitted in the synthesis of
À
the Ru C bond lengths concerning the p-cymene ring re-
À
vealed that Ru C(21) (2.3155(2) ꢅ) is considerably longer
À
than the other Ru C bond distances (2.2088(3)–
2.2657(3) ꢅ), which could be attributed to the location of
this carbon atom in an opposite pseudo-trans position with
respect to the s-bonded carbon atom (C(7)-Ru-C(21)=
172.60(3)8), which presumably has an important trans influ-
ence.
9a, the reaction was shown to produce a thienoACTHUNRTGNEUNG[2,3-c]pyrido-
nium derivative and [{RuCl(h6-p-cymene)}
2ACTHNGUTERN(NUG m Cl)2] as the
À
The analysis of the bond lengths of the new heterocycle is
more complicated. It seems that significant electronic deloc-
alization is present within the heterocyclic core because all
major compounds, thus offering the possibility of recycling
the ruthenium-containing starting material.
À
the C C bond lengths fall in the range expected for bond
Further information about the structure of these cationic
compounds was obtained by means of X-ray diffraction
analysis of 10c (Figure 4). The determination of the crystal
structure confirmed the molecular skeleton inferred from
the NMR spectroscopic data and strongly supports the aro-
matic nature proposed for these systems, as judged from the
almost perfectly planar disposition of the tricyclic core of
10c and from analysis of the bond lengths. In contrast with
the disposition observed in the X-ray structures of 7a and
8c, the nitrogen atom of the pyridyl fragment of 10c is co-
planar with rest of the atoms of this fragment (see the side
view given in Figure 4), thus confirming the restoration of
the aromaticity of this moiety.
It is also possible to obtain the organic products in a one-
pot procedure by starting from the easily accessible cyclo-
ruthenated complexes. For instance, compound 9a can be
synthesized by the sequential reaction of 2a with 3-hexyne
and CuCl2 in a one-pot preparation with methanol as the
solvent in a yield of 71%, which does not differ much from
that obtained from the stepwise procedure (Scheme 6). This
procedure was employed for the synthesis of the new
À
orders between single and double bonds. However, the C C
distances are not strictly identical and follow a pseudoalter-
nation pattern, not observed in the X-ray structures of truly
aromatic thienoACHTUNGTRENNUNG
[2,3-c]pyridines.[21] Unfortunately, this ten-
uous alternating pattern does not make possible the discrim-
ination between the different bonding modes. Therefore, al-
though the short Ru C(1) bond length suggests a h :h :h -
or even a h :h -coordination mode, the relatively similar C
C bond lengths can also be interpreted as h1:h4- or even as
h5-coordination. In all the interpretations, the delocalization
of the electron density involves only the carbon atoms be-
1
2
2
À
1
4
À
À
cause the C N bond lengths are characteristic of single
bonds. These observations, together with the fact that the
NPh group lies clearly out of the plane, indicate the pres-
ence of a nonaromatic structure for the new heterocyclic
ligand formed, which formally is a 4,5-diethyl-6-phenyl-6,7-
dihydrothienoACHTUNGTRENNUNG[2,3-c]pyridine. When a similar analysis was
carried out for 8c, the same structural trends were found for
the interaction of the Ru center with the p-cymene ligand
and with the new heterocycle formed, namely, 3,4-diethyl-2-
phenyl-2,9-dihydro-1H-pyrido-
ACHTUNGTRENNUNG[3,4-b]indole.
Release of the fused heterocy-
cles by oxidation with CuCl2:
Complexes 7a–c and 8a–c react
with CuCl2 in methanol at room
temperature to result in the vir-
tual quantitative liberation of
the respective fused heterocy-
clic products 9a–c and 10a–c
(Scheme 5). Purification by ex-
traction with CH2Cl2 followed
by flash chromatography over
Al2O3 allowed the isolation of
the targeted bis-heterocyclic
structures in 77–84% yield.
Full characterization of the
resulting cationic heteroarenes
was carried out on the basis of
their analytic and spectroscopic
data. The characteristic signals Scheme 5. Release of the new heterocycles by oxidation with CuCl2.
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Cycloruthenation of Heterocycles through Directed C H Bond Activation
FULL PAPER
Figure 4. Top and side view of 10c. Thermal ellipsoids are scaled to the 50% probability level. The hydrogen atoms and PF6 counteranion have been re-
moved for clarity.
unsaturated molecules into the
À
Ru C bond of cyclometalated
heterocyclic complexes com-
bined with the oxidative libera-
tion of the resulting organic
species. The synthetic protocol
is quite general and can be ap-
plied to thiophene, furan, and
pyrrole derivatives and to the
corresponding benzannulated
species. Furthermore, during
Scheme 6. One-pot synthesis of 9a, 11a, and 12a/12a’.
the course of these studies, a
thieno
[2,3-c]pyridinium derivatives 11a and isomers 12a and
new family of organometallic complexes was formed with an
unprecedented structure in the context of cyclometalation,
in which a nonplanar dearomatized hydropyridyl ring is co-
12a’, which were generated by the reaction between the cy-
cloruthenated complex 2a and diphenylacetylene or 3-phe-
nylpropynoate, respectively (Scheme 6).
ordinated to a {RuACTHNUTRGNEUNG
(p-cymene)} fragment in a h5 fashion and
Thus, alkynes substituted with aromatic groups or with
one electron-withdrawing group[22] are also accepted in this
synthetic approach. In the case of the unsymmetrical alkyne
3-phenyl propynoate, compounds 12a/12a’ were isolated as
a mixture of the corresponding isomers in a 82:18 ratio, that
is, assuming that the major isomer 12a contains the less-
bulky Ph group adjacent to the previously metalated carbon
atom, as typically observed in related reactions for unsym-
metrical alkynes with different steric requirements.[20a,c]
which probably has its origin in a metal–ligand cooperation
process. In addition to the considerable synthetic value of
the strategy developed in this study, the findings described
herein indicate that the widely accepted mechanism for this
type of annulation reaction might be more intricate than as-
sumed previously, at least when dealing with ruthenium
complexes. We hope that a better understanding of the fun-
damental aspects of the cyclometalation of heterocycles and
reactivity with alkynes will help in the design of better cata-
lysts for these appealing reactions.
1
Indeed, the H NMR spectroscopic data support this assig-
nation because the b proton of the thiophene ring of 12a
(major isomer) resonates upfield by approximately Dd=
0.4 ppm relative to the equivalent proton of 12a’ (minor
isomer). This shielding effect in 12a is attributed to the an-
Experimental Section
ACHTUNGTRENNUNGisotropic shielding caused by the presence of a phenyl group
in the surroundings of the b-thienyl proton.
General methods: The solvents were dried and distilled by using standard
procedures before use. All the reactions were carried out in an Ar atmos-
phere by using standard Schlenck techniques. Flash-column liquid chro-
matography was performed on aluminium oxide (90 neutral; 50–200 mm);
elemental analyses were carried out on a Perkin–Elmer 2400-B micro-
analyzer. 1H, 13C 31P, and 19F NMR spectra were recorded in CDCl3 or
CD3CN at 258C on Bruker AV300, AV400 or Varian Gemini 300 spec-
trometers (d in ppm, J in Hz) at an operating frequency of 300.13 or
Conclusion
We have reported an efficient and versatile approach to the
cyclometalation of heterocycles based on coordination-di-
400.13 MHz for H. The H and 13C spectra were referenced by using the
solvent signal as an internal standard, whereas the 19F NMR spectra were
referenced to CFCl3, and the 31P spectra were externally referenced to
H3PO4 (85%). ESI (ESI+) mass spectra were recorded using an Esquire
3000 ion-trap mass spectrometer (Bruker Daltonic GmbH) equipped
with a standard ESI/APCI source.
1
1
À
rected C H bond activation carried out by a combination of
ruthenium metalating agents and Cu
N
proach provides a new synthetic strategy for the synthesis of
fused bis-heterocyclic systems that relies on the insertion of
Chem. Eur. J. 2012, 00, 0 – 0
ꢄ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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E. P. Urriolabeitia et al.
X-ray crystallography: The X-ray data collection was performed on an
Oxford Diffraction Xcalibur2 diffractometer with graphite-monochro-
matic MoKa radiation (l=0.71073 ꢅ). A single crystal was mounted at
the end of a quartz fiber in a random orientation, covered with perfluori-
nated oil, and placed under a cold stream of N2. In all cases, a hemi-
sphere of data was collected based on w-scan or f-scan runs. The diffrac-
tion frames were integrated using the program CrysAlis RED[23] and the
integrated intensities were corrected for absorption with SADABS.[24]
The structures were solved and developed by using the Patterson and
Fourier methods.[25] All the non-hydrogen atoms were refined with aniso-
tropic displacement parameters. The hydrogen atoms were placed at ide-
alized positions and treated as riding atoms. Each hydrogen atom was as-
signed an isotropic displacement parameter equal to 1.2 times the equiva-
lent isotropic displacement parameter of its parent atom. The structures
mum volume, and the respective complex was precipitated by the addi-
tion of pentane (15 mL). The precipitate was washed with pentane (2ꢆ
10 mL) to afford the product as a microcrystalline solid.
2a: Orange solid (0.214 g, 57%). 1H NMR (CDCl3): d=8.02 (s, 1H; N=
CH), 7.75–7.64 (m, 4H; 2H Ph+2H thiophene), 7.45- 7.39 (m, 2H; Ph),
3
7.29 (m, 1H; Ph), 5.52 (d, 3JHH =5.1 Hz, 1H; p-cymene), 5.21 (d, JHH
=
3
3
5.3, 1H; p-cymene), 4.97 (d, JHH =5.1 Hz, 1H; p-cymene), 4.92 (d, JHH
=
5.3 Hz, 1H; p-cymene), 2.39 (sep, 3JHH =6.9 Hz, 1H; p-cymene), 2.04 (s,
3H; p-cymene), 0.96 (d, 3JHH =6.9 Hz, 3H; p-cymene), 0.84 ppm (d,
3JHH =6.9 Hz, 3H; p-cymene); 13C{1H} NMR (CDCl3): d=197.5 (C),
162.9 (CH), 155.1 (C), 137.8 (C), 136.8 (CH), 133.3 (CH), 128.9 (CH),
126.9 (CH), 122.3 (CH), 102.5 (C), 101.2 (C), 91.6 (CH), 87.9 (CH), 83.1
(CH), 82.5 (CH), 31.1 (CH), 23.0 (CH3), 21.5 (CH3), 18.9 ppm (CH3); MS
(ESI+): 457.9 [M+1H]+, 422.0 [MÀCl]+; elemental analysis calcd for
[C21H22ClNRuS]: C 55.19, H 4.85, N 3.06, S 7.02; found: C 55.54, H 4.44,
N 3.23; S 6.51; crystals suitable for X-ray diffraction studies were grown
by diffusion of pentane into a solution of 2a in dichloromethane at 88C.
2
were refined to Fo , and all reflections were used in the least-squares cal-
culations.[26]
CCDC-876368 (2a), CCDC-876369 (4b), CCDC-876370 (7a), CCDC-
876371 (8c), and CCDC-876372 (10c) contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of charge
2b: Orange solid (0.148 g, 41%). 1H NMR (CDCl3): d=7.87 (s, 1H; N=
CH), 7.77–7.66 (m, 2H; Ph), 7.53 (d, 3JHH =2.0 Hz, 1H; furan), 7.41–7.36
from
The
Cambridge
Crystallographic
Data
Centre
via
(m, 2H; Ph), 7.27 (m, 1H; Ph), 7.10 (d, 3JHH =2.0 Hz, 1H; furan), 5.53
www.ccdc.cam.ac.uk/data_request/cif.
4
(dd, 3JHH =6.0, 4JHH =1.2 Hz, 1H; p-cymene), 5.22 (dd, 3JHH =5.7, JHH
=
1.2 Hz, 1H; p-cymene), 4.95 (m, 2H; p-cymene), 2.43 (sep, 3JHH =6.9 Hz,
1H; p-cymene), 2.03 (s, 3H; p-cymene), 1.02 (d, 3JHH =6.9 Hz, 3H; p-
cymene), 0.89 ppm (d, 3JHH =6.9 Hz, 3H; p-cymene); 13C{1H} NMR
(CDCl3): d=176.0 (C), 158.7 (C), 155.6 (CH), 155.1 (C), 146.8 (CH),
129.2 (CH), 126.7 (CH), 122.2 (CH), 121.6 (CH), 102.4 (C), 101.5 (C),
90.9 (CH), 87.1 (CH), 82.8 (CH), 82.1 (CH), 31.4 (CH), 23.3 (CH3), 21.7
(CH3), 19.0 ppm (CH3); MS (ESI+): 441.7 [M+1H]+; elemental analysis
calcd for [C21H22ClNRuO]: C 57.20, H 5.03, N 3.18; found: C 56.94, H
4.78, N 3.01.
General procedure for the synthesis of Schiff bases: 1a–c, 3a, and 5a,b
were synthesized according to reported methods.[27] The derivatives 3b,c
and 5c were synthesized as follows:
3b,c: Aniline (182 mL, 2.00 mmol) and MgSO4 (0.5 g) were added to ben-
zofuran-2-carbaldehyde (243 mL, 2.00 mmol) or 1-methylindole-2-carbal-
dehyde (0.318 g, 2.00 mmol) dissolved in CH2Cl2 (15 mL). The suspension
was stirred overnight at room temperature in an argon atmosphere, the
resulting mixture was filtered, and the solvent was removed under re-
duced pressure. The oily yellow residue was recrystallized from CH2Cl2/
pentane to afford 3b or 3c as pale-yellow microcrystals.
3b: Yield: 0.385 g, 87%. 1H NMR (CDCl3): d=8.47 (s, 1H; HC=N),
7.71–7.64 (m, 2H), 7.47–7.41 (m, 3H), 7.36–7.28 ppm (m, 5H); 13C{1H}
NMR (CDCl3): d=156.1 (C), 153.3 (C), 151.3 (C), 148.6 (CH), 129.5
(CH), 128.0 (C), 127.4 (CH), 127.0 (CH), 123.8 (CH), 122.5 (CH), 121.4
(CH), 113.5 (CH), 112.5 ppm (CH); MS (ESI+): 222.0 [M+1H]+; ele-
mental analysis calcd for [C15H11NO]: C 81.43, H 5.01, N 6.33; found: C
81.77, H 4.87, N 6.06.
2c: Orange solid (0.218 mg, 59%). 1H NMR (CDCl3): d=7.73–7.69 (m,
3
3H; N=CH+2H Ph), 7.36 (m, 2H; Ph), 7.24 (m, 1H; Ph), 6.75 (d, JHH
=
3
3
2.3 Hz, 1H; pyrrole), 6.71 (d, JHH =2.3 Hz, 1H; pyrrole), 5.49 (dd, JHH
=
6.0, 4JHH =1.2 Hz, 1H; p-cymene), 5.14 (d, 3JHH =6.0, 4JHH =1.2 Hz, 1H;
p-cymene), 4.94 (dd, 3JHH =6.0, 4JHH =1.2 Hz, 1H; p-cymene), 4.89 (dd,
3JHH =6.0, 4JHH =1.2 Hz, 1H; p-cymene), 2.47 (sep, 3JHH =6.9 Hz, 1H; p-
cymene), 2.00 (s, 3H; p-cymene), 1.03 (d, 3JHH =6.9 Hz, 3H; p-cymene),
0.90 ppm (d, 3JHH =6.9 Hz, 3H; p-cymene); 13C{1H} NMR (CDCl3): d=
175.5 (C), 155.8 (C), 155.4 (CH), 141.0 (C), 130.1 (CH), 128.7 (CH),
125.8 (CH), 122.5 (CH), 117.8 (CH), 100.6 (C), 100.4 (C), 89.6 (CH), 87.9
(CH), 82.5 (CH), 81.9 (CH), 34.8 (s, NCH3), 31.1 (CH), 23.0 (CH3), 21.5
(CH3), 18.9 ppm (CH3); MS (ESI+): 454.9 [M+H]+, 418.9 [MÀCl]+; ele-
mental analysis calcd for [C22H25ClN2Ru]: C 58.21, H 5.55, N 6.17; found:
C 58.60, H 5.27, N 6.14.
1
3c: Yield: 0.430 g, 92%. H NMR (CDCl3): d=8.57 (s, 1H; HC=N), 7.71
3
(d, JHH =4.5 Hz, 1H; C6H4), 7.47–7.38 (m, 4H; 2H Ph+2H C6H4), 7.29–
7.26 (m, 3H; Ph), 7.18 (m, 1H; C6H4), 7.03 (s, 1H; indole), 4.29 ppm (s,
3H; NMe); 13C{1H} NMR (CDCl3): d=152.5 (CH), 152.4 (C), 140.6 (C),
135.6 (C), 129.4 (CH), 126.0 (C), 124.8 (CH), 122.1 (CH), 121.0 (CH),
120.4 (CH), 115.2 (CH), 112.0 (CH), 110.0 (CH), 32.3 ppm (CH3); MS
(ESI+): 235.1 [M+1H]+; elemental analysis calcd for [C16H14N2]: C 82.02,
H 6.02, N 11.96; found: C 81.88, H 5.95, N 12.34.
1
4a: Orange solid (0.259 g, 62%). H NMR (CDCl3): d=8.20 (m, 2H; N=
CH+C6H4), 7.93 (m, 1H; C6H4), 7.80 (m, 2H; Ph), 7.48–7.41 (m, 4H;
3H Ph+1H C6H4), 7.33 (m, 1H; C6H4), 5.91 (d, 3JHH =5.7 Hz, 1H; p-
cymene), 5.41 (d, 3JHH =5.7 Hz, 1H; p-cymene), 5.19 (d, 3JHH =5.7 Hz,
5c: 1-Methyl-pyrrole-2,5-dicarbaldehyde (0.274 g, 2.00 mmol) was dis-
solved in CH2Cl2 (15 mL) and treated with aniline (364 mL, 4.00 mmol) in
the presence of MgSO4 (0.5 g). The suspension was stirred overnight at
room temperature in an argon atmosphere. The resulting mixture was fil-
tered, the solvent was removed under reduced pressure, and the product
washed with pentane (2ꢆ10 mL) to yield an orange solid (465 mg, 81%).
1H NMR (CDCl3): d=8.43 (s, 2H; HC=N), 7.45–7.41 (m, 4H; Ph), 7.28–
7.22 (m, 6H; Ph), 6.83 (s, 2H; pyrrole), 4.51 ppm (s, 3H; NMe);
13C{1H} NMR (CDCl3): d=152.5 (C), 150.8 (CH), 135.4 (C), 129.3 (CH),
125.8 (CH), 120.9 (CH), 117.7 (CH), 34.9 ppm (CH3); MS (ESI+): 288.0
[M+1H]+; elemental analysis calcd for [C19H17N3]: C 79.41, H 5.96, N
14.62; found: C 79.13, H 5.66, N 14.68.
3
1H; p-cymene), 4.99 (d, JHH =5.7 Hz, 1H; p-cymene), 2.19–2.05 (m, 4H;
3
CH+CH3 p-cymene), 0.84 (d, JHH =6.9 Hz, 3H; p-cymene), 0.81 ppm (d,
3JHH =6.9 Hz, 3H; p-cymene); 13C{1H} NMR (CDCl3): d=199.7 (C),
163.8 (CH), 155.3 (C), 147.1 (C), 145.3 (C), 135.3 (C), 129.1 (CH), 128.7
(CH), 127.2 (CH), 126.9 (CH), 124.6 (CH), 123.6 (CH), 122.3 (CH),
106.1 (C), 100.3 (C), 92.7 (CH), 85.9 (CH), 84.7 (CH), 78.5 (CH), 31.4
(CH), 23.0 (CH3), 21.8 (CH3), 19.2 ppm (CH3); MS (ESI+): 508.0
+
+
À
[M+1H] , 472.1 [M Cl] ; elemental analysis calcd for [C25H24ClNRuS]:
C 59.22, H 4.77, N 2.76, S 6.32; found: C 58.76, H 4.52, N 2.57; S 5.91.
4b: Orange solid. (0.189 g, 47%). 1H NMR (CDCl3): d=8.09 (s, 1H; N=
CH), 8.00 (m, 1H; C6H4), 7.77 (m, 2H; Ph), 7.51–7.29 (m, 6H; 3H Ph+
General procedure for the synthesis of ruthenacycles 2a–c and 4a–c: The
corresponding imine (0.82 mmol) was added to a solution of [{RuClACTHNUTRGENUG(N p-
3H C6H4), 5.84 (dd, 3JHH =5.7, 4JHH =1.2 Hz, 1H; p-cymene), 5.46 (dd,
4
3JHH =6.0, 4JHH =1.4 Hz, 1H; p-cymene), 5.22 (dd, 3JHH =6.0, JHH
=
À
cymene)}
(m Cl)2] (0.250 g, 0.41 mmol) and Cu
N
3
4
1.4 Hz, 1H; p-cymene), 5.09 (dd, JHH =5.7, JHH =1.2 Hz, 1H; p-cymene)
2.31 (sep, 3JHH =6.9 Hz, 1H; p-cymene), 2.14 (s, 3H; p-cymene), 0.93 (d,
3JHH =6.9 Hz, 3H; p-cymene), 0.88 ppm (d, 3JHH =6.9 Hz, 3H; p-
cymene); 13C{1H} NMR (CDCl3): d=174.3 (C), 159.1 (C), 157.7 (C),
157.6 (CH), 155.6 (C), 137.3 (C), 129.5 (CH), 127.9 (CH), 127.5 (CH),
125.5 (CH), 123.3 (CH), 122.5 (CH), 112.6 (CH), 103.1 (C), 102.0 (C),
92.8 (CH), 85.9 (CH), 85.5 (CH), 80.8 (CH), 31.8 (CH), 23.4 (CH3), 22.3
1.64 mmol) in toluene (25 mL). The reaction mixture was stirred at 808C
(408C for 4c) under argon over 24 h. The resulting solution was evapo-
rated in vacuo to dryness. The residue was dissolved in dichloromethane
and filtered over celite. The resulting solution was concentrated to a
volume of approximately 2–3 mL and purified by flash chromatography
over neutral Al2O3 using MeOH/dichloromethane (1:99) as the eluent.
The orange fraction was collected and concentrated in vacuo to a mini-
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Cycloruthenation of Heterocycles through Directed C H Bond Activation
FULL PAPER
+
+
+
À
(CH3), 19.5 ppm (CH3); MS (ESI ): 491.9 [M+H] , 457.0 [M Cl] ; ele-
mental analysis calcd for [C25H24ClNRuO]: C 61.16, H 4.93, N 2.85;
found: C 61.51, H 4.96, N 2.78; crystals suitable for X-ray diffraction
studies were grown by diffusion of pentane into a solution of 4b in di-
chloromethane at 88C.
complex 2a–c or 4a–c (0.22 mmol) in MeOH (15 mL). The reaction mix-
ture was heated to reflux for the corresponding time (14 h for 7a, 16 h
for 7b, 4 h for 7c, 20 h for 8a, 30 h for 8b, and 6 h for 8c). The solvent
was removed under vacuum, and the residue was dissolved in dichloro-
methane and filtered through a plug of celite to afford a pale yellow solu-
tion, which was concentrated in vacuo to a minimum volume. Pentane
(15 mL) was added to the solution to precipitate the respective complex.
4c: Orange solid (0.170 g, 41%). 1H NMR (CDCl3): d=8.04 (s, 1H; N=
CH), 8.00 (m, 1H; C6H4), 7.81 (m, 2H; Ph), 7.45–7.26 (m, 5H; 3H Ph+
2H C6H4), 7.12 (m, 1H; C6H4), 5.88 (dd, 3JHH =5.7, 4JHH =1.2 Hz, 1H; p-
cymene), 5.46 (d, 3JHH =6.0 Hz, 1H; p-cymene), 5.19 (dd, 3JHH =5.7,
The solid was washed with pentane (3ꢆ10 mL).
3
7a: Yellow solid (0.123 g, 86%). 1H NMR (CDCl3): d=7.93 (d, JHH
=
4JHH =1.2 Hz, 1H; p-cymene), 5.04 (d, JHH =5.7 Hz, 1H; p-cymene), 3.79
3
5.7 Hz, 1H; thiophene), 7.27 (d, 3JHH =5.7 Hz, 1H; thiophene), 7.03 (m,
(s, 3H; NMe), 2.25 (sep, 3JHH =6.9 Hz, 1H; p-cymene), 2.12 (s, 3H; p-
2H; Ph), 6.73 (m, 1H; Ph), 6.43 (m, 2H; Ph), 5.96 (d, 3JHH =6.2 Hz, 1H;
cymene), 0.88 (d, 3JHH =6.9 Hz, 3H; p-cymene), 0.82 ppm (d, JHH
=
3
p-cymene), 5.85 (d, 3JHH =6.2 Hz, 1H; p-cymene), 5.76 (s, 1H;
6.9 Hz, 3H; p-cymene); 13C{1H} NMR (CDCl3): d=171.7 (C), 156.8
(CH), 155.9 (C), 145.0 (C), 141.3 (C), 135.9 (C), 128.9 (CH), 126.5 (CH),
125.8 (CH), 125.6 (CH), 122.3 (CH), 119.0 (CH), 109.9 (CH), 102.5 (C),
100.1 (C), 92.4 (CH), 85.4 (CH), 83.5 (CH), 79.3 (CH), 31.3, 31.2 (CH+
NCH3), 23.0 (CH3), 21.8 (CH3), 19.1 ppm (CH3); MS (ESI+): 506.9
3
C(H)(N)(Ru)), 5.62 (d, 3JHH =6.3 Hz, 1H; p-cymene), 5.37 (d, JHH
=
6.3 Hz, 1H; p-cymene), 2.85–2.68 (m, 3H; 1H p-cymene+2H CH2CH3),
2.49 (q, 3JHH =7.4 Hz, 2H; CH2CH3), 2.20 (s, 3H; p-cymene), 1.41–1.33
(m, 9H; 6H p-cymene+3H CH2CH3), 1.18 ppm (t, 3JHH =7.4 Hz, 3H
CH2CH3); 13C{1H} NMR (CDCl3): d=152.7 (C), 138.9 (CH), 129.0 (CH),
121.2 (CH), 119.7 (CH), 118.1 (C), 113.8 (CH), 109.3 (C), 108.6 (C),
105.6 (C), 98.6 (C), 96.5 (CH), 93.4 (CH), 91.9 (CH), 91.1 (CH), 76.7 (C),
43.9 (CH), 31.8 (CH), 25.1 (CH2), 24.6 (CH2), 23.5 (CH3), 22.8 (CH3),
18.3 (CH3), 14.6 (CH3), 11.5 ppm (CH3); 19F NMR (CDCl3): d=
À72.4 ppm (d, 1JFP =712.6 Hz; PF6); 31P{1H} NMR (CDCl3): d=
+
+
À
[M+H] , 468.9 [M Cl] ; elemental analysis calcd for [C26H27ClN2Ru]: C
61.96, H 5.40, N 5.56; found: C 62.04, H 5.78, N 5.22.
General procedure for the synthesis of ruthenacycles 6a,b: The corre-
sponding imine (0.41 mmol) was added to
a
solution of [{RuCl
ACHTUNGERTN(NUNG p-
À
cymene)}
(m Cl)2] (0.250 g, 0.41 mmol) and Cu
N
1
À144.2 ppm (sep, JFP =712.6 Hz; PF6); MS (ESI+): 503.9 [MÀPF6]+; ele-
1.64 mmol) in toluene (25 mL), and the reaction mixture was stirred at
1008C under argon over 24 h. The resulting solution was evaporated in
vacuo to dryness and the residue was dissolved in dichloromethane and
filtered over celite. The resulting solution was concentrated to a volume
of approximately 2–3 mL, and the crude product was purified by flash
chromatography over neutral Al2O3 with dichloromethane as the eluent.
The purple fraction (for 6a) or the first dark-red fraction (for 6b) was
collected, and the solvent was removed in vacuo to afford the desired
product.
6a: Purple solid (0.191 g, 56%). 1H NMR (À408C, CDCl3): d=8.18 (s,
2H; N=CH, major isomer), 8.15 (s, 2H; N=CH, minor isomer), 7.85 (m,
8H; Ph, 4H major isomer+4H minor isomer), 7.43 (m, 4H; Ph, 2H
major isomer+2H minor isomer), 7.31 (m, 8H; Ph, 4H major isomer+
4H minor isomer), 7.09 (d, 3JHH =6.0 Hz, 2H; p-cymene minor isomer),
7.00 (m, 2H; p-cymene major isomer), 5.02 (m, 4H; p-cymene, 2H major
isomer+2H minor isomer), 4.68 (d, 3JHH =5.3 Hz, 2H; p-cymene major
mental analysis calcd for [C27H32F6NPRuS] ·CH2Cl2: C 45.84, H 4.67, N
1.91, S 4.37; found: C 45.62, H 4.56, N 1.88, S 4.40; crystals suitable for
X-ray diffraction studies were grown by slow diffusion of pentane into a
solution of 7a in dichloromethane at room temperature.
7b: Yellow solid (0.118 g, 85%). 1H NMR (CDCl3): d=7.83 (d, JHH
3
=
2.5 Hz, 1H; furan), 7.06 (m, 2H; Ph), 6.96 (dd, 3JHH =2.5, 5JHH =0.8 Hz,
1H; furan), 6.76 (m, 1H; Ph), 6.41 (m, 2H; Ph), 6.20 (dd, 3JHH =6.2,
4JHH =1.4 Hz, 1H; p-cymene), 5.97 (dd, 3JHH =6.2, 4JHH =1.4 Hz, 1H; p-
cymene), 5.67–5.63 (m, 2H; C(H)(N)(Ru)+1H p-cymene), 5.56 (dd,
3JHH =6.2, 4JHH =1.4 Hz, 1H; p-cymene), 2.82–2.63 (m, 3H; 1H p-
cymene+2H CH2CH3), 2.45–2.30 (m, 2H; CH2CH3), 2.21 (s, 3H; p-
cymene), 1.43–1.31 (m, 9H; 6H p-cymene+3H CH2CH3), 1.18 ppm (t,
3JHH =7.3 Hz, 3H; CH2CH3); 13C{1H} NMR (CDCl3): d=152.8 (C), 129.1
(CH), 125.8 (C), 121.4 (CH), 117.5 (C), 113.9 (CH), 113.8 (CH), 109.1
(C), 106.4 (CH), 99.1 (C), 97.5 (C), 96.2 (CH), 93.0 (CH), 91.4 (CH), 90.2
(CH), 74.8 (C), 38.5 (CH), 31.8 (CH), 24.7 (CH2), 24.3 (CH2), 22.7 (CH3),
22.6 (CH3), 18.4 (CH3), 14.9 (CH3), 11.8 ppm (CH3); 19F NMR (CDCl3):
d=À72.4 ppm (d, 1JFP =712.6 Hz; PF6); 31P{1H} NMR (CDCl3): d=
isomer), 4.53 (m, 4H; p-cymene, 2H major isomer+2H minor isomer),
4.31 (d, 3JHH =5.6 Hz, 2H; p-cymene minor isomer), 3.02 (sep, JHH
=
3
6.4 Hz, 2H; p-cymene minor isomer), 2.50 (sep, 3JHH =6.8 Hz, 2H; p-
cymene major isomer), 2.31 (s, 6H; p-cymene, major isomer), 1.69 (s,
6H; p-cymene, minor isomer), 1.33 (d, 3JHH =6.4 Hz, 6H; p-cymene
1
À144.2 ppm (sep, JFP =712.6 Hz; PF6); MS (ESI+): 488.2 [MÀPF6]+; ele-
mental analysis calcd for [C27H32F6NPRuO]·CH2Cl2: C 46.87, H 4.78, N
minor isomer), 1.27 (d, 3JHH =6.4 Hz, 6H; p-cymene minor isomer), 0.87
1.95; found: C 46.78, H 4.41, N 2.01.
(d, 3JHH =6.8 Hz, 6H; p-cymene major isomer), 0.40 ppm (d, JHH
=
3
3
7c: Yellow solid (0.131 g, 92%). 1H NMR (CDCl3): d=7.50 (d, JHH
=
6.8 Hz, 6H; p-cymene major isomer); 13C{1H} NMR (CDCl3; d of broad
peaks assigned by HSQC/HMBC): d=209.3 (br; C), 163.1 (br; CH),
155.7 (C), 142.8 (C), 129.4 (CH), 127.7 (CH), 122.7 (CH), 111.9 (C), 97.8
(C), 94.6 (CH), 90.7 (CH), 79.9 (br; CH), 77.7 (br; CH), 30.3 (CH), 26.2
(CH3), 19.6 (CH3), 19.2 ppm (CH3); MS (ESI+): 830.0 [M]+; elemental
analysis calcd for [C38H40Cl2N2Ru2S]·CH2Cl2: C 51.21, H 4.63, N 3.06, S
3.51; found: C 51.56, H 5.01, N 2.78, S 3.50; crystals suitable for X-ray
diffraction studies were grown by slow evaporation of a solution of 6a in
dichloromethane at room temperature.
3.0 Hz, 1H; pyrrole), 7.06 (m, 2H; Ph), 6.72 (m, 1H; Ph), 6.38–6.35 (m,
3
3H; 2H Ph+1H pyrrole), 5.75 (m,2H; p-cymene), 5.63 (d, JHH =5.7 Hz,
3
1H; p-cymene), 5.51 (s, 1H; C(H)(N)(Ru)), 5.26 (d, JHH =5.7 Hz, 1H; p-
cymene), 3.51 (s, 3H; NCH3), 2.80–2.66 (m, 3H; 1H p-cymene+2H
CH2CH3), 2.51–2.35 (m, 2H; CH2CH3), 2.14 (s, 3H; p-cymene), 1.45–1.20
(m, 9H; 6H p-cymene+3H CH2CH3), 1.18 ppm (m, 3H; CH2CH3);
13C{1H} NMR (CDCl3): d=153.3 (C), 142.1 (CH), 128.8 (CH), 120.6
(CH), 116.4 (C), 113.5 (CH), 108.1 (C), 106.9 (C), 99.5 (CH), 99.0 (C),
96.3 (C), 93.7 (CH), 90.8 (CH), 89.0 (CH), 87.9 (CH), 73.9 (C), 36.7
(CH), 33.7 (NCH3), 32.0 (CH), 25.0 (CH2), 24.5 (CH2), 23.6 (CH3), 22.6
(CH3), 18.3 (CH3), 14.7 (CH3), 11.5 ppm (CH3); 19F NMR (CDCl3): d=
À72.4 ppm (d, 1JFP =712.6 Hz; PF6); 31P{1H} NMR (CDCl3): d=
6b: Red solid (0.130 g, 39%). 1H NMR (CDCl3; room temperature): d=
7.96 (s, 2H; N=CH), 7.82 (m, 4H; Ph), 7.42 (m, 2H; Ph), 7.32 (m, 2H;
4
Ph), 6.20 (br, 2H; p-cymene), 5.63 (br, 2H; p-cymene), 4.64 (dd, JHH
=
1
À144.2 ppm (sep, JFP =712.6 Hz; PF6); MS (ESI+): 501.0 [MÀPF6]+; ele-
1.2, 3JHH =6.0 Hz, 2H; p-cymene), 4.56 (dd, 4JHH =1.2, 3JHH =6.0 Hz, 2H;
p-cymene), 2.73 (sep, 3JHH =6.9 Hz, 1H; p-cymene), 2.15 (s, 3H; p-
cymene), 1.07 (d, 3JHH =6.9 Hz, 3H; p-cymene), 0.78 (d, 3JHH =6.9 Hz,
3H; p-cymene); 13C{1H} NMR (CDCl3; d of broad peaks assigned by
HSQC/HMBC): d=189.4 (C), 158.5 (C), 155.4 (C), 154.9 (CH), 128.8
(CH), 126.9 (CH), 121.8 (CH), 101.9 (C), 97.4 (C), 92.9 (CH), 89.5 (CH),
79.4 (CH), 30.3 (CH), 23.7 (CH3), 20.6 (CH3), 18.9 ppm (CH3); MS (ESI+
): 813.9 [M]+; elemental analysis calcd for [C38H40Cl2N2Ru2O]: C 56.08, H
4.95, N 3.44; found: C 55.83, H 5.27, N 3.69.
mental analysis calcd for [C28H35F6N2PRu]·1.5CH2Cl2: C 45.84, H 4.95, N
3.62; found: C 45.56, H 4.84, N 3.23.
8a: Yellow solid (0.141 g, 92%). 1H NMR (CDCl3): d=8.18 (m, 1H;
C6H4), 7.76 (m, 1H; C6H4), 7.60–7.53 (m, 2H; C6H4), 7.06 (m, 2H; Ph),
6.73 (m, 1H; Ph), 6.51 (m, 2H; Ph), 5.97 (dd, 3JHH =6.4, 4JHH =1.4 Hz,
4
1H; p-cymene), 5.87 (s, 1H; C(H)(N)(Ru)), 5.82 (dd, 3JHH =6.4, JHH
=
1.6 Hz, 1H; p-cymene), 5.73 (dd, 3JHH =6.4, 4JHH =1.6 Hz, 1H; p-
cymene), 5.27 (dd, JHH =6.4, JHH =1.6 Hz, 1H; p-cymene), 3.19 (m, 1H;
CH2CH3), 2.93 (m, 1H; CH2CH3), 2.70–2.60 (m, 3H; 1H p-cymene+2H
CH2CH3), 2.01 (s, 3H; p-cymene), 1.57 (d, 3JHH =6.9 Hz, 3H; p-cymene),
3
4
Synthesis of complexes 7a–c and 8a–c: KPF6 (0.040 g, 0.22 mmol) and 3-
hexyne (125 mL, 1.10 mmol) were added to a solution of the respective
Chem. Eur. J. 2012, 00, 0 – 0
ꢄ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
9
&
ÞÞ
These are not the final page numbers!

E. P. Urriolabeitia et al.
1.26–1.21 (m, 6H; CH2CH3), 1.08 ppm (d, 3JHH =6.9 Hz, 3H; p-cymene);
13C{1H} NMR (CDCl3): d=152.8 (C), 142.6 (C), 131.3 (C), 129.7 (CH),
128.9 (CH), 126.4 (CH), 126.2 (CH), 124.4 (CH), 121.2 (CH), 118.4 (C),
113.5 (CH), 109.3 (C), 105.8 (C), 102.5 (C), 99.6 (C), 96.8 (CH), 93.8
(CH), 93.0 (CH), 91.7 (CH), 77.5 (C), 44.2 (CH), 31.6 (CH), 25.1 (CH2),
23.7 (CH2), 23.0 (CH3), 22.7 (CH3), 18.1 (CH3), 13.9 (CH3), 11.1 ppm
(CH3); 19F NMR (CDCl3): d=À72.4 ppm (d, 1JFP =712.6 Hz; PF6);
31P{1H} NMR (CDCl3): d=À144.2 ppm (sep, 1JFP =712.6 Hz; PF6); MS
[MÀPF6]+; elemental analysis calcd for [C17H18F6NPS]: C 49.40, H 4.39,
N 3.39; found: C 49.12, H 4.76, N 3.47.
9b: Pale violet solid (0.049 g, 82%). 1H NMR (CDCl3): d=8.63 (d,
5JHH =0.9 Hz, 1H; N=CH), 8.28 (d, 3JHH =2.2 Hz, 1H; furan), 7.69–7.64
(m, 3H; Ph), 7.60–7.58 (m, 2H; Ph), 7.22 (dd, 3JHH =2.2, 5JHH =0.9 Hz,
1H; furan), 3.10 (q, 3JHH =7.6 Hz, 2H; CH2CH3), 2.89 (q, 3JHH =7.6 Hz,
3
2H; CH2CH3), 1.41 (t, 3JHH =7.5 Hz, 3H; CH2CH3), 1.12 ppm (t, JHH
=
7.5 Hz, 3H; CH2CH3); 13C{1H} NMR (CDCl3): d=157.3 (CH), 150.1 (C),
149.0 (C), 143.6 (C), 141.9 (C), 135.7 (C), 131.6 (CH), 130.5 (CH), 129.0
(CH), 126.2 (CH), 106.2 (CH), 23.6 (CH2), 23.4 (CH2), 14.5 (CH3),
13.8 ppm (CH3); 19F NMR (CDCl3): d=À72.4 ppm (d, 1JFP =712.6 Hz;
PF6); 31P{1H} NMR (CDCl3): d=À144.2 ppm (sep, 1JFP =712.6 Hz; PF6);
MS (ESI+): 252.2 [MÀPF6]+; elemental analysis calcd for
[C17H18F6NOP]: C 51.39, H 4.57, N 3.53; found: C 51.75, H 4.89, N 3.14.
(ESI+):
554.1
[MÀPF6]+;
elemental
analysis
calcd
for
[C31H34F6NPRuS]·CH2Cl2: C 49.05, H 4.63, N 1.79, S 4.09; found: C
49.12, H 4.66, N 1.47, S 4.32.
8b: Yellow solid (0.137 g, 91%). 1H NMR (CDCl3): d=8.02 (m, 1H;
C6H4), 7.57 (m, 1H; C6H4), 7.48–7.44 (m, 2H; C6H4), 7.06 (m, 2H; Ph),
6.75 (m, 1H; Ph), 6.48 (m, 2H; Ph), 6.09 (dd, 3JHH =6.4, 4JHH =1.6 Hz,
1H; p-cymene), 5.99 (dd, 3JHH =6.4, 4JHH =1.6 Hz, 1H; p-cymene), 5.85–
9c: Violet solid (0.050 g, 81%). 1H NMR (CDCl3): d=8.70 (s, 1H; N=
CH), 7.83 (d, 3JHH =2.8 Hz, 1H; pyrrole), 7.66–7.64 (m, 3H; Ph), 7.53–
7.49 (m, 2H; Ph), 6.80 (d, 3JHH =2.8 Hz, 1H; pyrrole), 4.02 (s, 3H;
NMe3), 3.08 (q, 3JHH =7.5 Hz, 2H; CH2CH3), 2.82 (q, 3JHH =7.5 Hz, 2H;
4
5.82 (m, 2H; C(H)(N)(Ru)+1H p-cymene), 5.32 (dd, 3JHH =6.4, JHH
=
1.6 Hz, 1H; p-cymene), 3.07 (m, 1H; CH2CH3), 2.93 (m, 1H; CH2CH3),
2.61–2.47 (m, 3H; 1H p-cymene+2H CH2CH3), 1.94 (s, 3H; p-cymene),
1.55 (t, 3JHH =7.4 Hz, 3H; CH2CH3), 1.26–1.16 ppm (m, 9H; 3H
CH2CH3 +6H p-cymene); 13C{1H} NMR (CDCl3): d=159.9 (C), 153.1
(C), 130.8 (CH), 129.1 (CH), 128.0 (C), 125.3 (CH), 123.8 (CH), 121.9
(C), 121.6 (CH), 117.9 (C), 113.9 (CH), 113.5 (CH), 109.4 (C), 99.1 (C),
95.2 (CH), 93.5 (CH), 92.7 (C), 92.0 (CH), 91.3 (CH), 75.5 (C), 38.8
(CH), 31.7 (CH), 24.6 (CH2), 24.1 (CH2), 23.0 (CH3), 22.9 (CH3), 18.1
3
3
CH2CH3), 1.39 (t, JHH =7.5 Hz, 3H; CH2CH3), 1.09 ppm (t, JHH =7.5 Hz,
3H; CH2CH3); 13C{1H} NMR (CDCl3): d=143.0 (CH), 142.6 (C), 149.0
(C), 142.0 (C), 132.4 (C), 131.2 (CH), 130.8 (C), 130.3 (CH), 129.4 (CH),
126.6 (CH), 101.9 (CH), 34.4 (NCH3), 23.2 (CH2), 22.7 (CH2), 14.7
1
(CH3), 14.4 ppm (CH3); 19F NMR (CDCl3): d=À72.4 ppm (d, JFP
=
1
712.6 Hz; PF6); 31P{1H} NMR (CDCl3): d=À144.2 ppm (sep, JFP
=
(CH3), 14.5 (CH3), 11.5 ppm (CH3); 19F NMR (CDCl3): d=À72.4 ppm (d,
712.6 Hz; PF6); MS (ESI+): 265.1 [MÀPF6]+; elemental analysis calcd for
1
1JFP =712.6 Hz; PF6); 31P{1H} NMR (CDCl3): d=À144.2 (sep, JFP
=
[C18H21F6N2P]: C 52.69, H 5.16, N 6.83; found: C 52.87, H 5.12, N 6.44.
712.6 Hz; PF6); MS (ESI+): 538.2 [MÀPF6]+; elemental analysis calcd for
[C31H34F6NPRuO]·1.5CH2Cl2: C 48.19, H 4.60, N 1.73; found: C 48.11, H
4.42, N 1.52.
10a: Pale yellow solid (0.054 g, 78%). 1H NMR (CD3CN): d=9.14 (s,
1H; N=CH), 8.73 (m, 1H; C6H4), 8.24 (m, 1H; C6H4), 7.96 (m, 1H;
C6H4), 7.89–7.78 (m, 4H; 1H C6H4 +3H Ph), 7.68 (m, 2H; Ph), 3.54 (q,
3JHH =7.6 Hz, 2H; CH2CH3), 2.98 (q, 3JHH =7.6 Hz, 2H; CH2CH3), 1.50
(t, 3JHH =7.6 Hz, 3H; CH2CH3), 1.14 ppm (t, 3JHH =7.6 Hz, 3H;
CH2CH3); 13C{1H} NMR (CD3CN): d=152.0 (C), 147.7 (C), 146.1 (C),
142.9 (C), 140.3 (CH), 139.3 (C), 136.9 (C), 132.8 (CH), 132.5 (C), 132.4
(CH), 131.2 (CH), 129.5 (CH), 128.0 (CH), 126.9 (CH), 125.1 (CH), 24.1
(CH2), 23.6 (CH2), 14.0 (CH3), 13.4 ppm (CH3); 19F NMR (CD3CN): d=
À72.1 ppm (d, 1JFP =712.6 Hz; PF6); 31P{1H} NMR (CD3CN): d=
1
8c: Pale yellow solid (0.144 g, 94%). H NMR (CDCl3): d=8.04 (m, 1H;
C6H4), 7.61 (m, 1H; C6H4), 7.35–7.27 (m, 2H; C6H4), 7.06 (m, 2H; Ph),
6.70 (m, 1H; Ph), 6.47 (m, 2H; Ph), 5.97 (dd, 3JHH =6.3, 4JHH =1.2 Hz,
1H; p-cymene), 5.83–5.81 (m, 2H; C(H)(N)(Ru)+1H p-cymene), 5.61
4
(dd, 3JHH =6.3, 4JHH =1.2 Hz, 1H; p-cymene), 5.15 (dd, 3JHH =6.3, JHH
=
1.2 Hz, 1H; p-cymene), 3.52 (s, 3H; NMe), 3.19 (m, 1H; CH2CH3), 2.90
(m, 1H; CH2CH3), 2.57–2.51 (m, 3H; 1H p-cymene+2H CH2CH3), 1.80
À144.5 ppm (sep, JFP =712.6 Hz; PF6); MS (ESI+): 318.2 [MÀPF6]+; ele-
3
1
(s, 3H; p-cymene), 1.58 (t, 3JHH =7.5 Hz, 3H; CH2CH3), 1.26 (d, JHH
=
3
mental analysis calcd for [C21H20F6NPS]: C 54.43, H 4.35, N 3.02, S 6.92.
found: C 54.52, H 4.16, N 3.37; S 6.68.
6.9 Hz, 3H; p-cymene), 1.20 (t, JHH =7.5 Hz, 3H; CH2CH3), 1.10 ppm (d,
3JHH =6.9 Hz, 3H; p-cymene); 13C{1H} NMR (CDCl3): d=153.6 (C),
146.0 (C), 129.2 (CH), 128.8 (CH), 123.5 (CH), 121.8 (CH), 121.6 (C),
120.7 (CH), 115.7 (C), 114.9 (C), 113.5 (CH), 110.9 (CH), 106.8 (C), 98.5
(C), 92.3 (2 CH), 90.2 (CH), 89.3 (CH), 88.5 (C), 75.0 (C), 35.8 (CH),
31.7 (CH), 29.8 (NCH3), 24.9 (CH2), 24.3 (CH2), 23.1 (CH3), 22.8 (CH3),
17.8 (CH3), 14.3 (CH3), 11.2 ppm (CH3); 19F NMR (CDCl3): d=
À72.4 ppm (d, 1JFP =712.6 Hz; PF6); 31P{1H} NMR (CDCl3): d=
1
10b. Pale violet solid (0.050 g, 75%). H NMR (CD3CN): d=9.01 (s, 1H;
N=CH), 8.46 (m, 1H; C6H4), 8.00–7.92 (m, 2H; C6H4), 7.77–7.71 (m, 4H;
1H C6H4 +3H Ph), 7.64–7.61 (m, 2H; Ph), 3.44 (q, 3JHH =7.6 Hz, 2H;
CH2CH3), 2.97 (q, 3JHH =7.6 Hz, 2H; CH2CH3), 1.49 (t, 3JHH =7.6 Hz,
3H; CH2CH3), 1.15 ppm (t, 3JHH =7.6 Hz, 3H; CH2CH3); 13C{1H} NMR
(CD3CN): d=161.3 (C), 153.1 (C), 151.2 (C), 142.9(C), 139.4 (C), 138.3
(C), 135.1 (CH), 132.4 (CH), 131.2 (CH), 130.2 (CH), 127.0 (CH), 126.8
1
À144.2 ppm (sep, JFP =712.6 Hz; PF6); MS (ESI+): 551.0 [MÀPF6]+; ele-
mental analysis calcd for [C32H37F6N2PRu]·1.5CH2Cl2: C 48.88, H 4.90, N
3.40; found: C 48.52, H 4.57, N 3.13; crystals suitable for X-ray diffrac-
tion studies were grown by slow diffusion of pentane into a solution of
8c in dichloromethane at room temperature.
(CH), 126.7 (CH), 120.8 (C), 114.2 (CH), 24.1 (CH2), 23.8 (CH2), 14.0
1
(CH3), 13.6 ppm (CH3); 19F NMR (CD3CN): d=À72.1 ppm (d, JFP
=
1
712.6 Hz; PF6); 31P{1H} NMR (CD3CN): d=À144.5 ppm (sep, JFP
=
712.6 Hz; PF6); MS (ESI+): 302.2 [MÀPF6]+; elemental analysis calcd for
[C21H20F6NOP]: C 56.38, H 4.51, N 3.13; found: C 56.62, H 4.16, N 3.49.
Synthesis of compounds 9a–c and 10a–c: CuCl2 (0.048 g, 0.35 mmol) was
10c. Pale yellow/green solid (0.058 g, 84%). 1H NMR (CD3CN): d=8.87
added to
a solution of the corresponding complex 7a–c or 8a–c
(0.15 mmol) dissolved in MeOH (10 mL). The reaction mixture was stir-
red at 258C for 10 min, and the solvent was removed in vacuo. The resi-
due was dissolved in dichloromethane (40 mL) and filtered through
celite. The resulting solution was concentrated to a small volume and pu-
rified by flash chromatography over neutral Al2O3 with MeOH/dichloro-
methane (1:99) as the eluent.
(s, 1H; N=CH), 8.48 (m, 1H; C6H4), 8.00–7.92 (m, 1H; C6H4), 7.78–7.71
(m, 4H; 1H C6H4 +3H Ph), 7.63–7.61 (m, 2H; Ph), 7.56 (m, 1H; C6H4),
3
3.98 (s, 3H; NCH3), 3.51 (q, 3JHH =7.6 Hz, 2H; CH2CH3), 2.95 (q, JHH
=
7.6 Hz, 2H; CH2CH3), 1.50 (t, 3JHH =7.6 Hz, 3H; CH2CH3), 1.14 ppm (t,
3JHH =7.6 Hz, 3H; CH2CH3); 13C{1H} NMR (CD3CN): d=146.6 (C),
146.2 (C), 143.5(C), 136.7 (C), 135.7 (C), 133.7 (C), 133.0 (CH), 131.9
(CH), 130.9 (CH), 128.2 (CH), 127.2 (CH), 126.3 (CH), 123.2 (CH),
119.8 (C), 111.9 (CH), 30.9 (NCH3), 23.6 (CH2), 23.5 (CH2), 14.4 (CH3),
13.7 ppm (CH3); 19F NMR (CD3CN): d=À72.1 ppm (d, 1JFP =712.6 Hz;
PF6); 31P{1H} NMR (CD3CN): d=À144.5 ppm (sep, 1JFP =712.6 Hz; PF6);
MS (ESI+): 315.1 [MÀPF6]+; elemental analysis calcd for [C22H23F6N2P]:
C 57.39, H 5.04, N 6.08; found: C 57.01, H 4.90, N 5.97; crystals suitable
for X-ray diffraction studies were grown by slow evaporation of a solu-
tion of 10c in dichloromethane at room temperature.
1
9a: Red solid (0.050 g, 77%). H NMR (CDCl3): d=9.05 (s, 1H; N=CH),
8.46 (d, 3JHH =5.4 Hz, 1H; thiophene), 7.74 (d, 3JHH =5.4 Hz, 1H; thio-
3
phene), 7.67–7.62 (m, 3H; Ph), 7.58–7.55 (m, 2H; Ph), 3.19 (q, JHH
=
7.8 Hz, 2H; CH2CH3), 2.91 (q, 3JHH =7.5 Hz, 2H; CH2CH3), 1.42 (t,
3JHH =7.8 Hz, 3H; CH2CH3), 1.13 ppm (t, 3JHH =7.5 Hz, 3H; CH2CH3);
13C{1H} NMR (CDCl3): d=151.0 (C), 148.7 (C), 144.9 (CH), 141.7 (C),
140.4 (CH), 136.4 (C), 135.5 (C), 131.7 (CH), 130.6 (CH), 126.3 (CH),
122.3 (CH), 23.9 (CH2), 23.3 (CH2), 14.7 (CH3), 14.0 ppm (CH3);
19F NMR (CDCl3): d=À72.4 ppm (d, 1JFP =712.6 Hz; PF6); 31P{1H} NMR
(CDCl3): d=À144.2 ppm (sep, 1JFP =712.6 Hz; PF6); MS (ESI+): 268.0
One-pot synthesis of 9a, 11a, and 12a,a’: KPF6 (0.040 g, 0.22 mmol) and
the corresponding alkyne (1.1 mmol) were added to the solution of com-
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Cycloruthenation of Heterocycles through Directed C H Bond Activation
FULL PAPER
plex 2a (0.100 g, 0.22 mmol) dissolved in MeOH (15 mL). The reaction
mixture was heated to reflux for 14 h and then cooled to room tempera-
ture. CuCl2 (0.068 g, 0.50 mmol) was added to the reaction mixture,
which was allowed to stir for 10 min. The solvent was removed under
vacuum, and the residue was dissolved in dichloromethane and filtered
through a plug of celite. The resulting solution was concentrated in vacuo
to a minimum volume of approximately 2–3 mL and purified by flash
chromatography over neutral Al2O3 with MeOH/dichloromethane (1:99)
as the eluent. Compound 9a displayed analytical and spectroscopic data
identical to those obtained with the stepwise procedure (0.065 g, 71%).
c) R. Grigg, V. Savic, Tetrahedron Lett. 1995, 36, 5737; d) S. Tollari,
F. Demartin, S. Cenini, G. Palmisano, P. Raimondi, J. Organomet.
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VOC (Gainesville, FL, U.S.) 2000, 1, 360; f) E. Capito, J. M. Brown,
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T. Satoh, M. Miura, Org. Lett. 2008, 10, 1159; h) Y. Kuninobu, K.
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5974; i) M. Wasa, B. T. Worrel, J.-Q. Yu, Angew. Chem. 2010, 122,
1297; Angew. Chem. Int. Ed. 2010, 49, 1275; j) S. Kawamorita, H.
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S. Mochida, T. Fukutani, T. Satoh, M. Miura, Org. Lett. 2011, 13,
706; l) D. Takeda, M. Yamashita, K. Hirano, T. Satoh, M. Miura,
Chem. Lett. 2011, 40, 1015; m) L. Ackermann, A. V. Lygin, Org.
Lett. 2011, 13, 3332.
11a: Pink solid (0.088 g, 79%). 1H NMR (CD3CN): d=9.55 (s, 1H; N=
3
CH), 8.65 (d, JHH =5.7 Hz, 1H; thiophene), 7.45–7.41 (m, 5H; Ph), 7.39–
7.35 (m, 4H; 3H Ph+1H thiophene), 7.31–7.26 (m, 2H; Ph), 7.18–
7.06 ppm (m, 5H; Ph); 13C{1H} NMR (CD3CN): d=152.0 (C), 147.5 (C),
147.0 (CH), 143.6 (C), 142.5 (CH), 136.9 (C), 136.6 (C), 135.1 (C), 132.2
(CH), 132.1 (C), 131.4 (CH), 130.7 (CH), 130.4 (CH), 130.3 (CH), 129.8
(CH), 129.5 (CH), 128.7 (CH), 127.8 (CH), 125.2 ppm (CH); 19F NMR
(CD3CN): d=À72.1 ppm (d, 1JFP =712.6 Hz; PF6); 31P{1H} NMR
(CD3CN): d=À144.2 ppm (sep, 1JFP =712.6 Hz; PF6); MS (ESI+): 364.3
[MÀPF6]+; elemental analysis calcd for [C25H18F6NPS]: C 58.94, H 3.56,
N 2.75, S 6.29; found: C 58.73, H 3.23, N 2.48, S 6.18.
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2012, 41, 3651; b) T. Satoh, M. Miura, Chem. Eur. J. 2010, 16, 11212;
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J. Am. Chem. Soc. 2008, 130, 12414; g) S. Nieto, P. Arnau, E. Serra-
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12a/12a’: Red solid (0.085 g, 76%; 12a/12a’=82:18 as determined by in-
1
1
tegration of the H NMR spectra). H NMR (CDCl3) d=9.78 (s, 1H; N=
3
CH 12a), 9.73 (s, 1H; N=CH 12a’), 8.69 (d, JHH =5.4 Hz, 1H; thiophene
12 a’), 8.60 (d, 3JHH =5.4 Hz, 1H; thiophene 12a), 7.96 (d, 3JHH =5.4 Hz
1H; thiophene 12a’), 7.75–7.24 (m, 11H; Ph+thiophene 12a+Ph 12a’),
3
3
4.12 (q, JHH =6.9 Hz, 2H; CO2CH2CH3 12a’), 3.86 (q, JHH =6.9 Hz, 2H;
CO2CH2CH312a), 0.90 (q, 3JHH =6.9 Hz, 3H; CO2CH2CH3 12a’),
0.78 ppm (t, JHH =6.9 Hz, 3H; CO2CH2CH3 12a); 13C{1H} NMR (CDCl3)
3
(only major isomer 12a): d=160.2 (C), 150.0 (C), 147.3 (CH), 142.5
(CH), 141.0 (C), 137.8 (C), 137.4 (C), 133.8 (C), 131.9 (CH), 131.8 (C),
130.4 (CH), 130.3 (CH), 129.3 (CH), 129.1 (CH), 125.9 (CH), 124.1
(CH), 63.6 (CH2), 13.1 ppm (CH3); 19F NMR (CDCl3): d=À72.4 ppm (d,
1
1JFP =712.6 Hz; PF6); 31P{1H} NMR (CDCl3): d=À144.2 ppm (sep, JFP
=
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712.6 Hz; PF6); MS (ESI+): 360.1 [MÀPF6]+; elemental analysis calcd for
[C22H18F6NO2PS]: C 52.28, H 3.59, N 2.77, S 6.34; found: C 52.31, H 3.47,
N 2.38, S, 6.77.
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Acknowledgements
Funding by the Ministerio de Economꢂa y Competitividad (MINECO;
Spain, Project CTQ2011–22589) and Gobierno de Aragꢀn (grupo E97) is
gratefully acknowledged. L.C. thanks MINECO (Spain) and CSIC
(Spain) for a Juan de la Cierva contract.
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Received: April 23, 2012
Revised: July 16, 2012
Published online: && &&, 0000
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Chem. Eur. J. 0000, 00, 0 – 0
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These are not the final page numbers!

À
Cycloruthenation of Heterocycles through Directed C H Bond Activation
FULL PAPER
Building fused bis-heterocycles! In a
new approach to the synthesis of
highly valuable fused bis-heteroarenes,
Cyclometalation
L. Cuesta, T. Soler,
E. P. Urriolabeitia* .......... &&&& — &&&&
À
acetylenes are inserted into the Ru C
bond of cyclometalated heterocyclic
complexes with an imine as a directing
group. This very general method
allows the “fusion” of a pyridinium
ring to thiophene, furan, pyrrole, and
the corresponding benzoannulated
derivatives (see scheme). A novel
family of organometallic intermediates,
which displays an unexpected structure
as a result of metal–ligand coopera-
tion, was identified.
Cycloruthenated Complexes from
Imine-Based Heterocycles: Synthesis,
Characterization, and Reactivity
toward Alkynes
Chem. Eur. J. 2012, 00, 0 – 0
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www.chemeurj.org
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