Ruthenium-Alkylidene Complexes with Sterically Rigid Fluorinated NHC Ligands

Article abstract of DOI:10.1002/ejoc.201801116

An efficient procedure for the preparation of novel olefin metathesis catalysts of Grubbs-Hoveyda type bearing sterically rigid NHC ligands has been developed. A preliminary evaluation of their catalytic activity has been performed on representative olefin metathesis reactions, such as RCM of malonates as well as self-metathesis of allylbenzene. As result, it was found that along with excellent robustness, new complexes demonstrate remarkable activity in metathesis of allylbenzene, outperforming commercially available Grubbs-Hoveyda catalyst in terms of yield and regioselectivity.

Full text of DOI:10.1002/ejoc.201801116

A Journal of
Accepted Article
Title: Ruthenium-alkylidene complexes with sterically rigid fluorinated
NHC ligands
Authors: Salekh Masoud, Timur Akmalov, Konstsntin Palagin, Fedor
Dolgushin, Sergey Nefedov, and Sergey N. Osipov
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201801116
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10.1002/ejoc.201801116
European Journal of Organic Chemistry
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Ruthenium-alkylidene complexes with sterically rigid fluorinated
NHC ligands
Salekh M. Masoud,[a] Timur R. Akmalov,[a] Konstantin A. Palagin,[a] Fedor M. Dolgushin,[a]
Sergey E. Nefedov,[b] and Sergey N. Osipov*[a]
Abstract: An efficient procedure for the preparation of novel olefin
metathesis catalysts of Grubbs-Hoveyda type bearing sterically rigid
NHC ligands has been developed. A preliminary evaluation of their
catalytic activity has been performed on representative olefin
metathesis reactions, such as RCM of malonates as well as self-
metathesis of allylbenzene. As result, it was found that along with
excellent robustness, new complexes demonstrate remarkable
activity in metathesis of allylbenzene, outperforming commercially
available Grubbs-Hoveyda catalyst in terms of yield and
regioselectivity.
The impact of fluorinated groups on the performance of
ruthenium-based olefin metathesis catalysts has been generally
studied by using definitely modified phosphine,[8] benzylidene[9]
ligands, as well as by the replacement of chlorine atoms at
ruthenium, e.g. with perfluoroalkanoates.[10] Meanwhile,
metathesis catalysts decorated with fluorinated NHC ligands are
still quite rare.[11] Some beneficial features found for such
complexes include increased solubility (e.g. in supercritical
carbon dioxide),[12] rate acceleration in ring closing metathesis
(RCM)[13] as well as a feasibility to apply fluorous separation
technique for efficient catalyst recycling.[14] The development of
new fluorinated NHC ligands, particularly unsymmetrical ones, to
afford enhanced stability, improved reactivity and selectivity is
therefore of interest.
Introduction
Recently we have developed an efficient route to the new family
of unsymmetrical N,N-diaryl imidazolium[15] and imidazolinium[16]
salts with bulky hexafluoroisopropylalkoxy [(CF3)2(OR)C-] group
in one of the N-aryl substituents and investigated their potential
as universal precursors of the corresponding NHC ligands for
metal catalysis. Some of ruthenium-alkylidene complexes bearing
these ligands demonstrated a good performance in olefin RCM
and cross-metathesis (CM).[16] With the aim of further evaluating
the effects of bulky fluorinated substituents installed in
unsymmetrical NHC ligand on the activity of the resulting
metathesis precatalysts, now we want to disclose the synthesis of
novel imidazoline-based tricyclic NHC precursors and the
corresponding ruthenium carbene complexes as well as
preliminary evaluation of their catalytic activity (Scheme 1).
Over the last two decades, olefin metathesis has experienced
dramatic development to become a powerful and highly versatile
method for the catalytic assembly of carbon-carbon bonds.[1]
Ruthenium metathesis catalysts bearing N-heterocyclic carbene
(NHC) ligands, commonly used for different synthetic purposes in
academia, have begun to find nowadays industrial applications.[2]
Despite prominent advances highlighting the great potential of
these ligand sets, particularly attention is focused on complexes
with unsymmetrical NHCs possessing unique opportunities for
rapid fine-turning of their catalytic properties by modifying the
NHC stereoelectronics.[3] The most attractive recent examples
include the usage of chelating unsymmetrical NHC ligands in
ruthenium-catalyzed Z-selective cross-metathesis.[4]
At the same time, fluorinated compounds have found widespread
applications in life and material sciences.[5] Particular attention is
focused on CF3-containing compounds due to the strongly
electron-withdrawing nature and large hydrophobic domain of CF3
group.[6] Such a way modification often beneficially change the
key physicochemical characteristics of molecules to bring them
more desired properties such as increased lipophilicity or
chemical stability.[7]
[a]
[b]
Dr. S.M. Masoud, T.R. Akmalov, K.A. Palagin, Prof. Dr. F.M.
Dolgushin, Prof. Dr. S.N. Osipov
A.N. Nesmeyanov Institute of Organoelement Compounds, Russian
Academy of Sciences, Vavilov str. 28, 119991, Moscow, Russia
E-mail: osipov@ineos.ac.ru
https://ineos.ac.ru/staff-4/osipov
Prof. S.E. Nefedov
N. S. Kurnakov Institute of General and Inorganic Chemistry,
Russian Academy of Sciences, Leninsky pr. 31, 119991, Moscow,
Russia
Scheme 1. Synthesis of metal complexes with fluorinated unsymmetrical NHC
ligands.
Supporting information for this article is given via a link at the end of
the document.
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10.1002/ejoc.201801116
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Results and Discussion
optimal for heterocyclization of activated intermediate A to
produce the desired imidazolinium triflate salt 7a (Scheme 4). The
final product can be easily purified by single recrystallization from
hexanes.
Previously[15] we have described the heterocyclic interconversion
of mesityl-substituted oxazolinium salt 1
the binucleophilic fluorinated arylamine
[17]
via the reaction with
mediated by
2
tetrafluoroboric acid to afford a mixture of hydroxyl-containing
imidazolium salt 3 along with unexpected tricyclic by-product 4
likely arising from additional heterocyclization upon the hydroxyl
group under the reaction conditions (Scheme 2).
Scheme 2. Reaction of oxazolium salt 1 with fluorinated aniline 2.
Scheme 3. Preparation of tricyclic salts 7a-c.
Figure 1. Molecular structure of salt 4. Selected bonds[Å], angles[°] and dihedral
angles [°]: O1-C13 1.424(1), O1-C10 1.425(1), N1-C1 1.327(1), N1-C2 1.419(1), N1-C13
1.458(1), N2-C1 1.305(1), N2-C14 1.482(1), C13-C14 1.524(1)Å, C13-O1-C10 115.02(8),
C1-N1-C13 109.81(9), C1-N2-C14 110.08(9), N2-C1-N1 112.71(10), N1N2C1/C2C3C9 42.8,
N1N2C1/C15C16C22 67.1.
The rigid tricyclic structure of 4 (Figure 1) has attracted our
attention as a potential NHC precursor for the construction of the
corresponding ruthenium olefin metathesis catalysts. After
several unsuccessful attempts to redirect the reaction towards the
preferential formation of tetrafluoroborate salt 4 we were pleased
to find an alternative two-step route for the selective preparation
of the desired compound as triflate salt 7a. Thus, the synthetic
Scheme 4. Proposed mechanism for the formation of 7a.
sequence included the reaction of hydroxyl-containing aniline 2a
The found conditions have proved to be suitable for the
preparation of two more tricyclic imidazolinium salts bearing
substituents of different bulkiness. For these purposes fluorinated
aniline 2b [16] with free ortho-position (R = H) and amidoaldehyde
5b with bulky 2,6-diisopropylphenyl group (Ar = DIPP) have been
applied as starting materials. As result, the corresponding salts
7b and 7c were obtained in acceptable yields (Scheme 3). As a
whole, the developed procedure gives good yields of 7a-c in the
range of 78-85 % for two steps even on a ten-gram scale (see
Experimental Section).
[17,18]
with readily available aryl-substituted amidoaldehyde 5a
to
afford benzoxazine-containing formamide 6a followed by
intramolecular heterocyclization via covalent activation of amide
group of the latter under strong acidic conditions to furnish 7a in
good yield (Scheme 3).
To perform the key cyclization step (6a → 7a) we have slightly
modified the protocol recently developed by Organ[19] for sterically
demanding imidazolinium salts. Thus, sequential addition of
stoichiometric amounts of triflic acid (TfOH) and its anhydride
(Tf2O) to the formamide 6a provided conditions for Vilsmeyer-
Haack reaction. The use of Hünig’s base has appeared to be
With these fluorinated unsymmetrical NHC precursors 7a-c in
hand, we prepared the new ruthenium complexes 8a-c in
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moderate to good yields following the conventional route via the
reaction of in situ generated carbene with commercially available
Hoveyda-Grubbs complex RuCl2(PCy3)(=CH(o-iPrO-C6H4)) HG-
I[20] of first generation. Purification by silica gel chromatography
afforded dark-green air stable solids 8a-c (Scheme 5).
Figure 2. Structure of complex 8a. Hydrogen atoms are omitted for clarity.
Selected bonds[Å], angles[o] and dihedral angles[o]: Ru1-C1 1.970(2), Ru1-Cl2 2.3420(5),
Ru1-Cl1 2.3593(5), O1-C13 1.415(3), O1-C12 1.435(3), N1-C1 1.346(3), N1-C2 1.437(3),
N1-C11 1.473(2), N2-C1 1.402(3), N2-C12 1.449(3), C11-C12 1.493, Ru1…C22 3.121(2),
C13-O1-C12
113.94(17),
C1-N1-C2
129.32(17),
Ru1N1N2C1av/C2C3C9
88.7,
Ru1N1N2C1av/C16C21C23 44.5.
Scheme 5. Synthesis of ruthenium carbene complexes 8a-c.
The complexes obtained were fully characterized by NMR
spectroscopy and elemental analysis. In H NMR spectra of 8a,
Figure 3. Structure of complex 8b. Hydrogen atoms are omitted for clarity.
Selected bonds[Å], angles[o] and dihedral angles[o]: Ru1-C1 1.965(2), Ru1-Cl2
2.3334(5), Ru1-Cl1 2.3412(5), O1-C9 1.420(2), O1-C12 1.437(2), N1-C1 1.388(2), N1-C12
1.441(2), N2-C1 1.335(2), N2-C13 1.472(2), Ru1…C3 3.149(1), C9-O1-C12 116.32(15), C1-
N1-C2 124.59(15), Ru1N1N2C1av/C2C3C8 46.6, Ru1N1N2C1av/C14C15C21 88.6.
1
8b and 8c measured at room temperature the absorptions of
intrinsic benzylidene protons are observed around 16.9, 16.3 and
16.6 ppm, respectively, as singlets in each case. The 13C NMR
spectra of the NHCs display the corresponding resonances at
217.1(8a), 217.8(8b) and 221.1(8c) ppm for the carbene center,
which are in the expected range for aryl-substituted imidazolidin-
2-ylidenes (see Experimental section). In addition, single crystals
of good quality for X-ray analysis from ruthenium complex 8a and
8b (Figures 2 and 3) were obtained by slow diffusion of hexane
into concentrated solution of benzene and CH2Cl2 respectively.
Before testing of the activity of newly obtained complexes bearing
unsymmetrical fluorinated NHC ligands, the thermal stability of
these catalysts was examined. For this purpose, each of the
ruthenium compounds was dissolved in deuterated benzene
under an argon atmosphere and heated for one week at 50 °C.
Degradation of the reference catalysts, with respect to 1,3,5-
trimethoxybenzene utilized as an internal standard, was
1
monitored by H NMR spectroscopy. All new catalysts exhibited
high stability under applied conditions (Figure 4). Even the least
lasting of them 8a decomposed by only 16% during one week (the
scale covers the range 80−100%). As expected, complexes
bearing a mesityl moiety were less stable than their 2,6-
diisopropylphenyl analogues 8c, which exhibited no signs of
decomposition.
Figure 4. Thermal stability of complexes 8a-c in benzene-d6 solution at 50°C
under argon monitored by 1H NMR. Decomposition was determined based on
the signal ratio between ruthenium compounds and internal standard 1,3,5-
trimethoxybenzene.
Then we performed the initial investigation of catalytic activities of
the prepared catalysts 8a-c in RCM reactions with diallyl- and
allylmetallylmalonates as well as in self-metathesis (SM) reaction
of allylbenzene following standard conditions for evaluation of
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olefin metathesis catalysts[21]
. The commercially available
complex RuCl2(H2IMes)(=CH-(o-iPrO-C6H4)) HG-II[22] (H2IMes =
1,3-bis(mesityl)imidazolidin-2-ylidene) was used as reference
catalyst to find out how modulating the electronic and steric
changes of the fluoroalkyl-substituted NHCs might affect the
catalytic activity. As a result, we found that the initiation rate of the
catalyst 8a in RCM of diethyl diallylmalonate (DEDAM) was
almost the same as compared to HG-II (Figure 5). On the other
hand, the initiation rates of catalysts 8b and 8c have proved to be
distinctly lower than in the case of 8a and HG-II displaying some
initiation period (about 30 min). Nevertheless, the full conversion
can be slowly achieved in 24 h, thus exhibiting high stability of the
catalysts in solution.
Figure 6. Catalytic activities of complexes 8a-c and HG-II in RCM of DEAMM.
The ring-closing metathesis of the more sterically hindered diethyl
allylmethallylmalonate was also achieved with the new catalysts
8a-c (Figure 6). A similar reactivity profile as starting from DEDAM
was observed, but the reaction rates were lower in all cases.
To estimate the efficiency of new complexes in cross-metathesis
allylbenzene has been selected as a model substrate. As it is well
known, the commercially available second generation Grubbs
and Hoveyda-Grubbs catalysts in self-metathesis of allylbenzene
usually induce isomerization of both starting compound and
product[23] via double-bond migration to form the corresponding
hard-separable mixture (Table 1, equation).
Figure 5. Catalytic activities of complexes 8a-c and HG-II in RCM of DEDAM.
Figure 7. Steric maps of complexes 8a, 8b, and HG-II
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We found that new complexes 8a-c revealed in this reaction a
good reactivity and much higher selectivity as compared with HG-
II (Table 1). Thus, the yields of target self-metathesis product B
were noticeably higher in all cases under catalysis with 8a-c and
the formation of undesirable isomerization by-products ISO did
not succeed 1.0 % in most trials exhibiting two order higher ratios
of B to ISO by comparing with HG-II (Table 1, entries 4, 7).
The observed selectivity could be addressed to the rigid structure
of NHCs, which forces the more bulky aromatic fragment of the
unsymmetrical ligand to locate in close proximity to ruthenium
center. This in turn hampers the catalyst decomposition via
ruthenium-hydride pathways and blocks any isomerization
processes.[24] For proposed mechanism of preventing the
isomerization process see Supporting Information.
In addition, the steric maps and buried volumes of catalytic
pockets for 8a and 8b were calculated[25] and compared with
analogous data obtained for HG-II[26] (Figure 7). Despite the fact
that the resulting values of %VBur for 8a and 8b were only slightly
higher than for HG-II (36.2 and 34.4 vs 34.0) namely the fixed
location of tricyclic NHC ligand could be considered as a critical
point for observed selectivity. Noteworthy, the absence of methyl
group in 8b does not significantly affect the distance of fused
aromatic ring to ruthenium center (Ru1…C22 = 3.12 Å for 8a,
Ru1…C3 = 3.15 Å for 8b, see Figure 2 and 3, respectively).
Table 1. Catalytic activity of complexes 8a-c and HG-II in self-metathesis of allylbenzenea
Entry
1
[Ru] cat.
HG-II
HG-II
HG-II
8a
Time, h
Conversion, %
88.0
Yield B,b %
83.8
Yield ISO, %
16.1
16.7
23.6
0.1
Ratio B/ISO
1
2
4
1
2
4
1
2
4
1
2
4
5
2
89.9
83.3
5
3
98.1
76.4
3
76.1
99.9
760
388
270
752
154
81
4
5
8a
77.8
99.7
0.3
6
8a
81.3
99.6
0.4
8b
75.3
99.9
0.1
7
8
8b
77.7
99.3
0.7
9
8b
82.3
98.8
1.2
10
11
12
8c
74.3
99.2
0.8
123
108
88
8c
76.2
99.1
0.9
8c
80.1
98.9
1.1
a
Conditions: THF; catalyst’s loading 0.1 mol%; concentration of allylbenzene 3 M; reaction temperature 35 °C.
Conversions and yields were determined by 1H NMR spectroscopy and GC-MS analysis. b E/Z ratios in all cases were
in a range of 4:1 to 5:1 respectively.
position with N-aryl-N-(2-oxoethyl) formamide followed by
intramolecular heterocyclization under strong acidic conditions.
The salts obtained were further successfully used as precursors
of the corresponding NHC ligands for the preparation of three
novel ruthenium carbene complexes of Grubbs-Hoveyda type.
Their performance has been tested in representative olefin
metathesis reactions. As a result, they have proved to be active
in ring closing metathesis of diallyl- and allylmetallyl malonates.
Conclusion
We have developed an efficient route to new tricyclic
imidazolinium salts decorated with two geminal trifluoromethyl
groups. The synthetic strategy is based on condensation of
anilines containing bulky hexafluoroisopropoxy group in ortho-
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compounds studied in MeCN: nitrogen was used as the nebulizer gas (1.2
bar) and dry gas (8.0 L min–1, 200 °C). All the MS spectra were recorded
with 1 Hz frequency and processed using Bruker Data Analysis 4.0
software package.
The initiation rates in most cases were lower as compared to
benchmark catalyst. Nevertheless, the full conversion can be
slowly achieved in 1-2 days, thus exhibiting high stability of the
catalysts in solution. On the other hand, new catalysts gave
interesting results in self-metathesis of allylbenzene,
outperforming commercially available Grubbs-Hoveyda catalyst
in terms of yield and regioselectivity. In particular, the reaction
with N-Mes-containing catalysts (8a and 8b) led to remarkably low
content of isomerization products (0.1%) in almost quantitative
yield of desired self-metathesis product. The observed selectivity
can be addressed to close proximity of fused aromatic ring in rigid
tricyclic NHC ligand to ruthenium center that may hampering
isomerization pathways during catalytic cycle. The data obtained
can be useful in design and synthesis of new more selective olefin
metathesis catalysts.
Purification of allylbenzene[24] and syntheses of 2-(2-amino-3,5-
dimethylphenyl)-1,1,1,3,3,3-hexafluoro-propan-2-ol (2a),[16a] 2-(2-amino-
5-methylphenyl)-1,1,1,3,3,3-hexafluoro-propan-2-ol (2b),[15] N-mesityl-N-
(2-oxoethyl)formamide
(5a),[17]
N-(2,6-diisopropylphenyl)-N-(2-
oxoethyl)formamide (5b)[18b] were carried out according to literature
procedures.
General procedure for synthesis of compounds 6. The corresponding
fluorinated aniline (1 eqiuv.) was added to a solution of N-mesityl-N-(2-
oxoethyl)formamide
or
N-(2,6-diisopropylphenyl)-N-(2-oxoethyl)-
formamide (1 equiv.) in petroleum ether (0.1 M). After complete dissolution
of aniline 0.1 equiv. of glacial acetic acid was added. The reaction mixture
was allowed to stir at room temperature overnight. Next day the reaction
mixture was filtered to yield corresponding oxazine 6 as precipitate.
Experimental Section
Synthesis of N-{[6,8-dimethyl-4,4-bis(trifluoromethyl)-2,4-dihydro-
1H-benzo[d][1,3]oxazin-2-yl]methyl}-N-mesitylformamide (6a). Yield:
80%. 1H NMR (400 MHz, CDCl3): δ = 8.11 (s, 1H, CHO), 7.16 (s, 1H, HAr),
7.06 (s, 1H, HAr), 6.99 (s, 1H, HAr), 6.95 (s, 1H, HAr), 5.46 (br.s, 1H, NH),
4.87 (d, JH,H = 5.7 Hz, 1H, OCHN), 4.40 (dd, JH,H = 14.1, 8.0 Hz, 1H, CH2),
3.54 (dd, JH,H = 14.1, 3.1 Hz, 1H, CH2), 2.31 (s, 3H, CH3), 2.29 (s, 3H, CH3),
2.23 (s, 3H, CH3), 2.21 (s, 3H, CH3), 2.20 ppm (s, 3H, CH3); 13C NMR (101
MHz, СDCl3): δ = 165.8 (CHO), 139.1 (CAr), 139.0 (CAr), 136.3 (CAr), 136.3
(CAr), 132.8 (CAr), 130.1 (CAr), 130.0 (CAr), 129.9 (CAr), 127.4 (CAr), 124.9
(CAr), 123.0 (q, 1JC,F = 290 Hz, CF3), 122.3 (q, 1JC,F = 287 Hz, CF3), 112.2
(CAr), 80.6 (NCO), 77.74 (hept, 2JC,F = 29 Hz), 50.1 (CH2), 21.0 (CH3), 21.0
(CH3), 18.2 (CH3), 18.2 (CH3), 16.8 (CH3); 19F NMR (376 MHz, CDCl3): δ
= -72.17 (d, 4JF,F = 7.6 Hz, 3F, CF3), -75.71 ppm (d, 4JF,F = 7.6 Hz, 3F, CF3).
IR (KBr): 휈̃ = 3367, 2950, 2921, 2880, 1671, 1497, 1354, 1262, 1233, 1207,
1178, 1110, 1097, 1057, 977, 961, 923, 862, 793, 752, 742, 709, 585, 538,
442 cm-1. ESI-TOF: (+)MS calcd for C23H25F6N2O2 [M+H]+ m/z 475.1815,
found m/z 475.1812, δ 0.6 ppm. Elemental analysis calcd for
C23H24F6N2O2 (%): C, 58.23; H, 5.10; N, 5.90; found C, 58.31; H, 5.17; N,
5.75.
All solvents were freshly distilled from appropriate drying agents before
use. All other reagents were recrystallized or distilled as necessary.
Syntheses of ruthenium complexes were performed under an argon
atmosphere using a standard Schlenk technique. Analytical TLC was
performed with Merck silica gel 60 F254 plates. Visualization was
accomplished by UV light (254 and 366 nm), spraying by Ce(SO4)2
solution in 5% H2SO4 or KMnO4 solution in water. Column chromatography
was carried out using Merck silica gel 60 (230−400 mesh ASTM) and ethyl
acetate/petroleum ether as eluent.
NMR spectra were recorded at room temperature on Bruker AC-200, AV-
400, AV-500, AV-600 spectrometers operating at 200, 300, and 500 MHz
for 1H; 101, 126, and 151 MHz for 13C; and 376 MHz for 19F (CF3CO2H as
reference). The chemical shifts are frequency referenced relative to the
residual undeuterated solvent peaks.
Mass spectra were measured on Agilent 5977A quadrupole instrument,
using electron ionization (EI-MS) source with sample injection via Agilent
7890 gas chromatograph.[27] Measurements were performed in full-scan
(scan range from m/z 35 to m/z 500) mode with ionization energy set at 70
eV, source temperature set at 230°C and transfer capillary temperature
set at 300°C. Separation was carried out on Agilent HP-5ms fused silica
capillary column (30 m length; 250 µm I.D.; 0.25 µm film thicknesses, (5%
Phenyl)-methylpolysiloxane) using He (5.0 grade, NII KM) as carrier gas
with average velocity at 30 cm/sec. Temperature program was started at
60°C and fixed for 2 min, then increased at a rate of 20ºC/min to 300ºC
and held for 6 min. Injection port temperature was set at 300°C and
operated in split mode at 10:1 ratio with sample injection volume of 1 µl.
The spectra were processed using Bruker Data Analysis 4.0 software
package with NIST 14 spectra database.
Synthesis of N-mesityl-N-{[6-methyl-4,4-bis(trifluoromethyl)-2,4-
dihydro-1H-benzo[d][1,3]oxazin-2-yl]methyl}formamide (6b). Yield:
62%. 1H NMR (400 MHz, CDCl3): δ = 8.09 (s, 1H, CHO), 7.29 (s, 1H, HAr),
7.15 (d, 3JH,H = 8.1 Hz, 1H, HAr), 6.98 (s, 1H, HAr), 6.95 (s, 1H, HAr), 6.83
3
(d, JH,H = 8.2 Hz, 1H, HAr), 5.17 (br.s, 1H, NH), 4.91 (dd, JH,H = 7.0, 2.8
Hz, 1H, OCHN), 4.29 (dd, JH,H = 14.2, 7.1 Hz, 1H, CH2), 3.59 (dd, JH,H
=
14.2, 3.1 Hz, 1H, CH2), 2.31 (s, 6H, CH3), 2.22 ppm (s, 6H, CH3); 13C NMR
(101 MHz, CDCl3): δ = 165.7 (CHO), 141.0 (CAr), 138.9 (CAr), 136.4 (CAr),
136.3 (CAr), 136.2 (CAr), 131.9 (CAr), 130.6 (CAr), 130.0 (CAr), 129.8 (CAr),
127.5 (CAr), 122.9 (q, 1JC,F = 290 Hz, CF3), 122.2 (q, 1JC,F = 286 Hz, CF3),
119.4 (CAr), 112.3 (CAr), 80.8 (NCO), 78.4-77.4 [m, C(CF3)2], 50.33(CH2),
21.04 (CH3), 21.01 (CH3), 18.3 (CH3), 18.2 ppm (CH3); 19F NMR (376 MHz,
C6D6): δ = -72.30 – -72.40 (m, 3F, CF3), -75.71 – -75.81 ppm (m, 3F, CF3).
IR (KBr): 휈̃ = 3353, 2946, 2923, 2876, 1672, 1619, 1511, 1474, 1424, 1355,
1277, 1262, 1231, 1183, 1100, 1087, 1012, 988, 966, 862, 823, 752, 746,
710, 584, 537 cm-1. ESI-TOF: (+)MS calcd for C22H23F6N2O2 [M+H]+
m/z 461.1658, found m/z 461.1657, δ 0.2 ppm. Elemental analysis calcd
for C22H22F6N2O2 (%): C, 57.39, H, 4.82, N, 6.08, found C, 57.24, H, 5.12,
N, 6.15.
High-resolution mass spectra were obtained on a Bruker maXis Q-TOF
instrument (Bruker Daltonik GmbH, Bremen, Germany) equipped with an
electrospray ionization (ESI) ion source. The experiments were performed
in positive (+)MS ion mode (HV Capillary: 4500 V; Spray Shield Offset: –
500 V) and negative (–)MS ion mode (HV Capillary: 2000 V; Spray Shield
Offset: –500 V) with a scan range of m/z 50–1200 (or m/z 50–2000 for Ru
complexes). External calibration of the mass spectrometer was achieved
using a low-concentration tuning mix solution (Agilent Technologies).
Direct syringe injection of solutions in DCM or MeCN was used at flow rate
of 5 μL/min. For Ru complexes studied in DCM: nitrogen was used as the
nebulizer gas (0.4 bar) and dry gas (4.0 L min–1, 180 °C). For organic
Synthesis
of
N-(2,6-diisopropylphenyl)-N-{[6,8-dimethyl-4,4-
bis(trifluoromethyl)-2,4-dihydro-1H-benzo[d][1,3]oxazin-2-
yl]methyl}formamide (6c). Additional purification by column
chromatography (petroleum ether/ethyl acetate 8:1) was required to obtain
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201801116
European Journal of Organic Chemistry
FULL PAPER
the product of satisfactory quality. Yield: 71%. 1H NMR (400 MHz, CDCl3):
δ = 8.14 (s, 1H, CHO), 7.40 (t, JH,H = 7.7 Hz, 1H, HAr), 7.26 (dd, JH,H = 7.7
Hz, 1.4, 1H, HAr), 7.21 (dd, JH,H = 7.8 Hz, 1.4, 1H, HAr), 7.16 (s, 1H, HAr),
ppm (s, 3F, SCF3). IR (KBr): 휈̃ = 3016, 2926, 1624, 1605, 1282, 1268,
1227, 1212, 1158, 1109, 1089, 1058, 1031, 973, 861, 750, 743, 712, 639,
570, 518 cm-1. ESI-TOF: (+)MS calcd for C23H23F6N2O [M–OTf]+
m/z 457.1709, found m/z 457.1709, δ < 0.1 ppm; (–)MS calcd for CF3O3S
[OTf]– m/z 148.9526, found m/z 148.9526, δ < 0.1. Elemental analysis
calcd for C24H23F9N2O4S (%): C, 47.53; H, 3.82; N, 4.62; found C, 47.42;
H, 3.93; N, 4.60.
5.51 (d, JH,H = 6.8 Hz, 1H, NH), 4.89-4.83 (m, 1H, NCHO), 4.64 (dd, JH,H
=
13.9, 9.1 Hz, 1H, CH2), 3.36-3.26 (m, 2H, CH2, CHMe2), 2.89 (hept, 3JH,H
= 6.7 Hz, 1H, CHMe2), 2.29 (s, 3H, CH3), 2.22 (s, 3H, CH3), 1.32 [d, 3JH,H
= 6.9, 3H, CH(CH3)2], 1.16 [d, 3JH,H = 6.8, 3H, CH(CH3)2], 1.14 [d, 3JH,H
=
6.9, 3H, CH(CH3)2], 1.02 ppm [d, 3JH,H = 6.8, 3H, CH(CH3)2]; 13C NMR (101
MHz, CDCl3): δ = 165.5 (CHO), 147.9 (CAr), 147.3 (CAr), 139.0 (CAr), 135.8
(CAr), 132.8 (CAr), 130.4 (CAr), 130.1 (CAr), 127.9 (CAr), 125.0 (CAr), 124.9
(CAr), 124.8 (CAr), 112.5 (CAr), 80.2 (NCO), 78.5-77.3 [m, C(CF3)2], 51.5
(CH2), 28.7 (CMe2), 27.9 (CMe2), 25.3 [C(CH3)2], 25.2 [C(CH3)2], 23.64
[C(CH3)2], 23.59 [C(CH3)2], 21.1 (CH3), 16.8 ppm (CH3); 19F NMR (376
MHz, CDCl3): δ = -72.29 (q, 4JF,F = 8.4 Hz, CF3), -75.83 ppm (q, 4JF,F = 8.4
Hz, CF3). IR (KBr): 휈̃ = 3356, 2969, 2951, 2932, 2866, 1674, 1499, 1461,
1368, 1277, 1257, 1221, 1205, 1179, 1147, 1094, 1056, 978, 965, 863,
811, 773, 749, 743, 712 cm-1. ESI-TOF: (+)MS calcd for C26H31F6N2O2
[M+H]+ m/z 517.2284, found m/z 517.2288, δ 0.8 ppm. Elemental analysis
calcd for C26H30F6N2O2 (%): C, 60.46; H, 5.85; N, 5.42; found C, 60.61; H,
5.89; N, 5.20.
Synthesis
of
2-mesityl-7-methyl-5,5-bis(trifluoromethyl)-3a,5-
dihydro-3H-benzo[d]imidazo[5,1-b][1,3]oxazin-2-ium triflate (7b).
Yield: 82%. 1H NMR (400 MHz, CDCl3): δ = 9.24 (s, 1H, NCHN), 7.93 (d,
JH,H = 8.2 Hz, 1H, HAr), 7.48 (s, 1H, HAr), 7.31 (d, JH,H = 7.9 Hz, 1H, HAr),
6.97 (s, 2H, HAr), 6.23 (d, JH,H = 6.3 Hz, 1H, NCHO), 4.98 (dd, JH,H = 14.3,
7.3 Hz, 1H, CH2), 4.08 (dd, JH,H = 14.2, 2.4 Hz, 1H, CH2), 2.43 (s, 3H, CH3),
2.34 (s, 3H, CH3), 2.32 (s, 3H, CH3), 2.18 ppm (s, 3H, CH3); 13C NMR (101
MHz, CDCl3) δ 157.2 (NCN), 141.3 (CAr), 139.4 (CAr), 135.7 (CAr), 134.3
(CAr), 133.4 (CAr), 130.3 (CAr), 130.0 (CAr), 129.6 (CAr), 129.4 (CAr), 127.9
(CAr), 121.9 (q, 1JC,F = 289 Hz, CCF3), 121.8 (CAr), 121.3 (q, 1JC,F = 286 Hz,
CCF3), 120.4 (q, 1JC,F = 289 Hz, SCF3), 115.8 (CAr), 84.3 (NCO), 79.0-77.4
[m, C(CF3)2], 57.9 (CH2), 21.5 (CH3), 21.1 (CH3), 17.4 (CH3), 16.9 ppm
(CH3); 19F NMR (376 MHz, CDCl3): δ = -71.82 (q, 4JF,F = 7.6 Hz, 3F, CCF3),
-75.98 (q, 4JF,F = 7.2 Hz, 3F, CCF3), -78.75 ppm (s, 3F, SCF3). IR (KBr): 휈̃
= 3075, 2966, 2926, 2862, 1624, 1294, 1268, 1234, 1219, 1172, 1097,
1038, 971, 859, 821, 751, 744, 709, 701 cm-1. ESI-TOF: (+)MS calcd for
C22H21F6N2O [M–OTf]+ m/z 443.1553, found m/z 443.1551, δ 0.5 ppm;
(–)MS calcd for CF3O3S [OTf]– m/z 148.9526, found m/z 148.9524, δ 1.3
ppm. Elemental analysis calcd for C23H21F9N2O4S (%): C, 46.63; H, 3.57;
N, 4.73; found C, 46.40; H, 3.68; N, 4.74.
General procedure for synthesis of compounds 7. Triflic acid (120 µL,
1.37 mmol) was added to the solution of oxazine 6 (1.37 mmol) in toluene
(30 mL), and the mixture was stirred at r.t. for 15 min. Then, triflic anhydride
(230 µL, 1.37 mmol) was added, and the reaction mixture was heated at
65 °C for 1.5 h. DIPEA (720 µL, 4.11 mmol) was added, and the reaction
mixture was heated at 80 °C for another 1.5 h. After cooling to r.t., solvents
were removed under reduced pressure, the residue was dissolved in
CH2Cl2 (30 mL) and the solution was washed with water (3 × 20 mL). The
organic layer was dried using MgSO4, filtered, and concentrated under
reduced pressure. The crude product was triturated in petroleum ether to
yield 7 as beige solid.
Synthesis
of
2-(2,6-diisopropylphenyl)-7,9-dimethyl-5,5-
bis(trifluoromethyl)-3a,5-dihydro-3H-benzo[d]imidazo[5,1-
b][1,3]oxazin-2-ium triflate (7c). Yield: 98%. 1H NMR (400 MHz, CDCl3):
δ = 8.70 (s, 1H, NCHN), 7.47 (t, JH,H = 7.8 Hz, 1H, HAr), 7.33 (s, 1H, HAr),
Scaled-up one pot procedure for the synthesis of 7a-c. The
corresponding fluorinated aniline (34.0 mmol) was added to a solution of
N-mesityl-N-(2-oxoethyl)formamide or N-(2,6-diisopropylphenyl)-N-(2-
oxoethyl)-formamide (1 equiv.) in petroleum ether (300 mL). After
complete dissolution of aniline 0.2 mL of glacial acetic acid was added.
The reaction mixture was allowed to stir at room temperature overnight.
Next day the reaction mixture was filtered. The resulting precipitate was
dissolved in 150 mL of toluene, then triflic acid (2.4 mL, 27.1 mmol) was
added, and the mixture was stirred at r.t. for 15 min. Then, triflic anhydride
(4.6 mL, 27.1 mmol) was added, and the reaction mixture was heated at
65 °C for 1.5 h. DIPEA (14.2 mL, 81.3 mmol) was added, and the reaction
mixture was heated at 80 °C for another 1.5 h. After cooling to r.t., solvents
were removed under reduced pressure, the residue was dissolved in
CH2Cl2 (150 mL) and the solution was washed with water (3 × 80 mL). The
organic layer was dried using MgSO4, filtered, and concentrated under
reduced pressure. The crude product was triturated in petroleum ether to
yield 7 (75-98%) as beige solid.
7.29-7.22 (m, 3H, HAr), 6.12 (d, JH,H = 6.0 Hz, 1H, NCHO), 4.95 (dd, JH,H =
14.7, 6.4 Hz, 1H, CH2), 4.08 (d, JH,H = 14.6 Hz, 1H, CH2), 3.00 (hept, 3JH,H
= 6.7 Hz, 1H, CHMe2), 2.79 (hept, 3JH,H = 6.6 Hz, 1H, CHMe2), 2.41 (s, 3H,
ArCH3), 2.40 (s, 3H, ArCH3), 1.28 [d, 3JH,H = 6.7 Hz, 3H C(CH3)2], 1.24 [d,
3JH,H = 6.7 Hz, 3H C(CH3)2], 1.19 [d, 3JH,H = 6.7 Hz, 3H C(CH3)2], 1.10 ppm
3
[d, JH,H = 6.8 Hz, 3H C(CH3)2]; 13C NMR (101 MHz, CDCl3): δ = 158.1
(NCN), 146.4 (CAr), 145.9 (CAr), 139.1 (CAr), 135.4 (CAr), 132.3 (CAr), 131.9
(CAr), 128.8 (CAr), 128.4 (CAr), 125.7 (CAr), 125.0 (CAr), 124.9 (CAr), 121.9
(q, 1JF,F = 289 Hz, CF3), 121.4 (q, 1JF,F = 286 Hz, CF3), 120.4 [m, C(CF3)2],
117.5 (CAr), 85.8 (NCO), 59.8 (CH2), 28.5 (CMe2), 28.5 (CMe2), 24.8
[C(CH3)2], 24.2 [C(CH3)2], 23.8 [C(CH3)2], 23.6 [C(CH3)2], 21.5 (ArCH3),
16.6 ppm (ArCH3); 19F NMR (376 MHz, CDCl3): δ = -71.91 – -72.01 (m, 3F,
CCF3), -76.39 – -76.48 (m, 3F, CCF3), -78.82 ppm (s, 3F, SCF3). IR (KBr):
휈̃ = 2971, 2934, 2876, 1623, 1284,1269, 1218, 1085, 1059, 973, 866, 809,
749, 743, 712 cm-1. ESI-TOF: (+)MS calcd for C26H29F6N2O [M–OTf]+
m/z 499.2179, found m/z 499.2179, δ < 0.1 ppm; (–)MS calcd for CF3O3S
[OTf]– m/z 148.9526, found m/z 148.9525, δ 0.7 ppm. Elemental analysis
calcd for C27H29F9N2O4S (%): C, 50.00; H, 4.51; N, 4.32; found C, 50.26;
H, 4.64; N, 4.38.
Synthesis of 2-mesityl-7,9-dimethyl-5,5-bis(trifluoromethyl)-3a,5-
dihydro-3H-benzo[d]imidazo[5,1-b][1,3]oxazin-2-ium triflate (7a).
Yield: 75%. 1H NMR (400 MHz, CDCl3): δ = 9.04 (s, 1H, NCHN), 7.34 (s,
1H, HAr), 7.29 (s, 1H, HAr), 6.96 (s, 2H, HAr), 6.13 (d, JH,H = 6.3 Hz, 1H,
NCHO), 4.94 (dd, JH,H = 14.4, 6.5 Hz, 1H, CH2), 4.08 (d, JH,H = 14.4 Hz,
1H, CH2), 2.46 (s, 3H, CH3), 2.40 (s, 3H, CH3), 2.30 (s, 6H, CH3), 2.19 ppm
(s, 3H, CH3); 13C NMR (101 MHz, CDCl3): δ = 158.0 (NCN), 141.3 (CAr),
139.0 (CAr), 135.3 (CAr), 135.2 (CAr), 134.7 (CAr), 132.1 (CAr), 130.1 (CAr),
129.3 (CAr), 128.5 (CAr), 125.8 (CAr), 121.9 (q, 1JC,F = 288 Hz, CCF3), 121.3
(q, 1JC,F = 286 Hz, CCF3), 120.4 (q, 1JC,F = 320 Hz, SCF3), 117.5 (CAr), 85.6
General procedure for synthesis of ruthenium complexes 8. In a
flame-dried Schlenk flask, imidazolinium salt 7 (0.42 mmol) was mixed with
15 mL of anhydrous toluene. The resulting mixture was degassed three
times and cooled to -5 °C; then KHMDS (0.45 mL of 1 M solution in THF,
0.45 mmol) was added to the mixture under an argon atmosphere. The
reaction mixture was stirred for 2 min before Hoveyda catalyst HG-I (0.19
g, 0.32 mmol) was added. Then mixture was stirred for 100 min at r.t.
During this time, the reaction mixture changed color from brown to green.
Once complete, solvents were removed from the reaction mixture under
reduced pressure, and the resulting substance was purified by column
2
(NCO), 78.2 [hept, JC,F = 30 Hz, C(CF3)2], 57.6 (CH2), 21.4 (CH3), 21.1
(CH3), 17.4 (CH3), 16.8 ppm (CH3); 19F NMR (376 MHz, CDCl3): δ = -71.90
(q, 4JC,F = 8.5 Hz, 3F, CCF3), -76.13 (q, 4JC,F = 8.4 Hz, 3F, CCF3), -78.98
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201801116
European Journal of Organic Chemistry
FULL PAPER
chromatography using petroleum ether/ethyl acetate (3:1) as eluent to
yield Hoveyda-type catalyst 8 as a green solid.
NMR (151 MHz, C6D6): δ = 292.5 (Ru=CH), 221.1 (NCN), 153.1 (CAr),
149.6 (CAr), 148.0 (CAr), 144.3 (CAr), 137.8 (CAr), 137.6 (CAr), 137.0 (CAr),
134.4 (CAr), 130.4 (CAr), 130.3 (CAr), 128.4 (CAr), 125.7 (CAr), 125.4 (CAr),
125.1 (CAr), 122.8 (CAr), 122.4 (CAr), 119.1 (CAr), 113.6 (CAr), 84.9 (NCO),
75.3 (OCMe2), 61.9 (CH2), 28.6 (ArCMe2), 27.6 (ArCMe2), 27.1
[ArC(CH3)2], 25.6 [ArC(CH3)2], 24.0 [ArC(CH3)2], 23.6 [ArC(CH3)2], 23.3
(ArCH3), 22.4 (ArCH3), 21.9 [OC(CH3)2], 21.0 ppm [OC(CH3)2]; 19F NMR
(376 MHz, C6D6): δ = -71.84 (q, 4JC,F = 11.5 Hz, 3F, CF3), -72.89 ppm (q,
4JC,F = 11.0 Hz, 3F, CF3). ESI-TOF: (+)MS calcd for C36H40Cl2F6N2O2Ru
[M]+• m/z 818.1413, found m/z 818.1403, δ 1.2 ppm. Elemental analysis
calcd for C36H40Cl2F6N2O2Ru (%): C, 52.81; H, 4.92; N, 3.42; found C,
52.96; H, 5.01; N, 3.22.
Synthesis
of
dichloro(2-isopropoxybenzylidene)[2-mesityl-7,9-
dimethyl-5,5-bis(trifluoromethyl)-3a,5-dihydro-3H-
benzo[d]imidazo[5,1-b][1,3]oxazin-1-ylidene]ruthenium(II) (8a). The
product was additionally purified by recrystallization from methanol. Yield:
59%. 1H NMR (500 MHz, CD2Cl2): δ = 16.91 (s, 1H, CHAr), 7.63 (ddd, J =
8.7, 7.1, 1.8, 1H, HAr), 7.43 (s, 1H, HAr), 7.41 (s, 2H, HAr), 7.21 (s, 1H, HAr),
7.07-6.98 (m, 4H, HAr), 5.62 (d, JH,H = 5.6 Hz, 1H, NCHO), 5.19-5.11 (m,
1H, CHMe2), 4.50 (d, JH,H = 6.9 Hz, 1H, CH2), 4.04 (d, JH,H = 13.0 Hz, 1H,
CH2), 3.37 (s, 3H, ArCH3), 2.52 (s, 3H, ArCH3), 2.51 (s, 3H, ArCH3), 2.44
(s, 3H, ArCH3), 2.40 (s, 3H, ArCH3), 1.76-1.50 ppm [m, 6H, C(CH3)2]; 13
C
NMR (126 MHz, CD2Cl2): δ = 296.4 (Ru=CH), 217.1 (NCN), 153.1 (CAr),
144.9 (CAr), 140.0 (CAr), 138.9 (CAr), 138.0 (CAr), 137.4 (CAr), 137.1 (CAr),
134.3 (CAr), 131.2 (CAr), 130.6 (CAr), 129.6 (CAr), 125.8 (CAr), 123.4 (q, 1JC,F
CCDC 1850675 (for 4), 1850674 (for 8a) and 1854390 (for 8b) contain the
supplementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic Data Centre
1
= 290 Hz, CF3), 123.1 (CAr), 123.0 (CAr), 122.4 (q, JC,F = 287 Hz, CF3),
2
119.1 (CAr), 114.0 (CAr), 84.9 (NCO), 78.4 [hept, JC,F = 31 Hz, C(CF3)2],
Ring-closing metathesis of diethyl diallylmalonate or diethyl
allylmethallylmalonate. An NMR tube with a screw-cap septum top was
charged with starting material (60 µmol) solution in CD2Cl2 (0.5 mL) under
argon atmosphere. The sample was equilibrated at 30°C in the NMR probe
before 6 mM catalyst solution in CD2Cl2 (0.1 mL, 0.6 µmol) was added via
syringe. Data points were collected every 2-3 minutes. The conversion to
RCM product was determined by comparing the ratio of the integrals of the
methylene protons in the starting materials, δ 2.61 (dt, JH,H = 7.4, 1.1 Hz,
4H) for DEDAM and 2.72-2.61 (m, 4H) for DEAMM, with those in the
products, δ 2.98 (s, 4H) and 2.98-2.85 (m, 4H) respectively.
76.1 (OCMe2), 59.8 (CH2), 22.4 (ArCH3), 22.2 (ArCH3), 21.6 (ArCH3), 21.4
(ArCH3), 19.6 [C(CH3)2], 18.6 ppm [C(CH3)2]; 19F NMR (376 MHz, CD2Cl2):
δ = -72.52 (s, 3F, CF3), -73.74 ppm (s, 3F, CF3). ESI-TOF: (+)MS calcd for
C33H34Cl2F6N2O2Ru [M]+• m/z 776.0943, found m/z 776.0934, δ 1.0 ppm.
Elemental analysis calcd for C33H34Cl2F6N2O2Ru (%): C, 51.04; H, 4.41; N,
3.61; found C, 50.84; H, 4.52; N, 3.84. Suitable for X-ray crystals of 8a
were grown by slow diffusion of hexane vapors in C6H6 solution.
Synthesis of dichloro(2-isopropoxybenzylidene)[2-mesityl-7-methyl-
5,5-bis(trifluoromethyl)-3a,5-dihydro-3H-benzo[d]imidazo[5,1-
b][1,3]oxazin-1-ylidene]ruthenium(II) (8b). Yield: 30%. 1H NMR (400
MHz, C6D6): δ = 16.31 (s, 1H, CHAr), 9.91 (d, JH,H = 7.9 Hz, 1H, HAr), 7.65
(s, 1H, HAr), 7.34 (dd, JH,H = 8.0, 1.8 Hz, 1H, HAr), 7.13-7.08 (m, 1H, HAr),
6.98 (dd, JH,H = 7.5, 1.6 Hz, 1H, HAr), 6.79 (s, 1H, HAr), 6.72 (s, 1H, HAr),
6.66 (t, JH,H = 7.3 Hz, 1H, HAr), 6.44 (d, JH,H = 8.3 Hz, 1H, HAr), 4.97 (d, JH,H
= 6.7 Hz, 1H, NCHO), 4.65 (hept, 3JH,H =5.9 Hz, 1H, OCHMe2), 3.54 (dd,
JH,H = 13.0, 6.9 Hz, 1H, CH2), 3.37 (dd, JH,H = 12.9, 1.7 Hz, 1H, CH2), 2.33
(s, 3H, ArCH3), 2.27 (s, 3H, ArCH3), 2.17 (s, 3H, ArCH3), 1.94 (s, 3H,
ArCH3), 1.81 [d, 3JH,H = 6.0 Hz, 3H, C(CH3)2], 1.56 ppm [d, 3JH,H = 6.0 Hz,
3H, C(CH3)2]; 13C NMR (126 MHz, C6D6): δ = 294.4 (Ru=CH), 217.8 (NCN),
153.1 (CAr), 144.5 (CAr), 139.5 (CAr), 138.8 (CAr), 138.6 (CAr), 137.6 (CAr),
137.2 (CAr), 136.7 (CAr), 133.0 (CAr), 130.1 (CAr), 130.0 (CAr), 124.1 (CAr),
123.4 (q, 1JC,F = 290 Hz, CF3), 122.8 (CAr), 122.7 (q, 1JC,F = 286 Hz, CF3),
122.4 (CAr), 116.9 (CAr), 113.4 (CAr), 83.0 (NCO), 78.5 [hept, 2JC,F = 30 Hz,
C(CF3)2], 75.1 (OCMe2), 58.9 (CH2), 22.5 (ArCH3), 22.3 (ArCH3), 21.1
(ArCH3), 18.2 [C(CH3)2], 17.7 ppm [C(CH3)2]; 19F NMR (376 MHz, C6D6): δ
= -71.61 (q, 4JF,F = 8.1 Hz, 3F, CF3), -73.69 ppm (q, 4JF,F = 8.1 Hz, 3F, CF3).
ESI-TOF: (+)MS calcd for C32H32Cl2F6N2O2Ru [M]+• m/z 762.0786, found
Self-metathesis of allylbenzene. A flame-dried Schlenk flask was
charged with allylbenzene (355 mg, 3.0 mmol) in anhydrous degassed
THF (0.4 mL) under argon atmosphere. The mixture was stirred at 35°C
before 15 mM catalyst solution in THF (0.2 mL, 3 µmol) was added via
syringe. Data points were collected over an appropriate period of time by
taking the probes (~0.1 mL) from the reaction mixture. The reaction was
quenched using excess of ethyl vinyl ether (0.5 mL). The conversion to CM
product was determined by GCMS and NMR.
Thermal Stability Test. An NMR tubes with a screw-cap septum top were
charged with solutions of complexes 8a-c (12.9 µmol) and 1,3,5-
trimethoxybenzene (internal standard, 2.2 mg, 12.9 µmol) in C6D6 (0.6 mL)
under argon atmosphere. The samples were equilibrated at 50°C for one
week. Data points were collected after appropriate time intervals. The rate
of decomposition of complexes was determined by comparing the ratio of
the integrals of methyl protons the internal standard, δ 3.31 (s, 9H) with
those for the characteristic Ru=CHAr, δ 17.00 (for 8a), 16.31 (for 8b) and
16.59 (for 8c) (s, 1H).
m/z 762.0783,
δ 0.3
ppm.
Elemental
analysis
calcd
for
C32H32Cl2F6N2O2Ru (%): C, 50.40; H, 4.23; N, 3.67; found C, 50.44; H,
4.43; N, 3.86. Suitable for X-ray crystals of 8b were grown by slow diffusion
of hexane in DCM solution.
Acknowledgements
Synthesis
of
dichloro(2-isopropoxybenzylidene)[2-(2,6-
This work was financially supported by the Russian Scientific
Foundation (grant RSF № 16-13-10364). Authors also thank Dr.
M.A. Zotova for the assistance in kinetic experiments.
diisopropylphenyl)-7,9-dimethyl-5,5-bis(trifluoromethyl)-3a,5-
dihydro-3H-benzo[d]imidazo[5,1-b][1,3]oxazin-1-ylidene]rutheni-
um(II) (8c). Yield: 38%. 1H NMR (400 MHz, C6D6): δ = 16.59 (s, 1H,
Ru=CH), 7.53 (s, 1H, HAr), 7.32 (t, JH,H = 7.7 Hz, 1H, HAr), 7.24 (dd, JH,H
=
Keywords:
N-Heterocyclic
carbenes
•
unsymmetrical
7.8, 1.7 Hz, 1H, HAr), 7.15-7.04 (m, 3H, HAr), 6.97 (dd, JH,H = 7.5, 1.7 Hz,
1H, HAr), 6.61 (t, JH,H = 7.4 Hz, 1H, HAr), 6.37 (d, JH,H = 8.3 Hz, 1H, HAr),
5.12 (d, JH,H = 5.6 Hz, 1H, NCHO), 4.57 (hept, 3JH,H = 6.2 Hz, 1H, OCHMe2),
3.79 (dd, JH,H = 12.8, 5.6 Hz, 1H, CH2), 3.65-3.53 (m, 5H, ArCH3,
ArCHMe2), 3.41 (d, JH,H = 12.9 Hz, 1H, CH2), 1.95 (s, 3H, ArCH3), 1.66 [d,
3JH,H = 6.1 Hz, 3H, C(CH3)2], 1.42 [d, 3JH,H = 6.1 Hz, 3H, C(CH3)2], 1.33 [d,
3JH,H = 6.7 Hz, 3H, C(CH3)2], 1.20 [d, 3JH,H = 6.4 Hz, 3H, C(CH3)2], 1.12 [d,
imidazolium salts • fluorinated NHC ligands • alkene metathesis
[1]
[2]
Handbook of Metathesis, ed. R. H. Grubbs and A. G. Wenzel, Wiley-VCH,
Weinheim, 2015.
a) Olefin Metathesis-Theory and Practice, ed. K. Grela, Wiley, Hoboken,
NJ, 2014; b) C. S. Higman, J. A. M. Lummiss, D. E. Fogg, Angew. Chem.
Int. Ed., 2016, 55, 3552-3565; Angew. Chem., 2016, 128, 3612-3626.
3JH,H = 6.5 Hz, 3H, C(CH3)2], 1.01 ppm [d, 3JH,H = 6.8 Hz, 3H, C(CH3)2]; 13
C
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[3]
a) L. Benhamou, E. Chardon, G. Lavigne, S. Bellemin-Laponnaz, V.
César, Chem. Rev. 2011, 111, 2705-2733; b) J. Tornatzky, A.
Kannenberg, S. Blechert, Dalton Trans. 2012, 41, 8215-8225; c) F. B.
Hamad, T. Sun, S. Xiao, F. Verpoort, Coord. Chem. Rev. 2013, 257,
2274-2292; d) D. J. Nelson, S. P. Nolan, Chem. Soc. Rev. 2013, 42,
6723-6753.
[17] A. Fürstner, M. Alcarazo, V. César, C. W. Lehmann, Chem. Commun.
2006, 2176-2178.
[18] a) D. Katayev, Y.-X. Jia, A. K. Sharma, D. Banerjee, C. Besnard, R. B.
Sunoj, E. P. Kündig, Chem. Eur. J. 2013, 19, 11916-11927; b) A.
Schumacher, M. Bernasconi, A. Pfaltz, Angew. Chem. Int. Ed., 2013, 52,
7422-7425; Angew. Chem. Int. Ed., 2013, 125, 7570-7573; c) G. A. Price,
A. R. Bogdan, A. L. Aguirre, T. Iwai, S. W. Djuric, M. G. Organ, Catal. Sci.
Technol., 2016, 6, 4733-4742; d) R. Kyan, K. Sato, N. Mase, N.
Watanabe, T. Narumi, Org. Lett. 2017, 19, 2750-2753.
[4]
[5]
a) S. Shahane, C. Bruneau, C. Fischmeister, ChemCatChem 2013, 5,
3436-3459; b) T. P. Montgomery, A. M. Johns, R. H. Grubbs, Catalysts
2017, 7, 87; c) A. Dumas, R. Tarrieu, T. Vives, T. Roisnel, V. Dorcet, O.
Baslé, M. Mauduit, ACS Catal. 2018, 8, 3257-3262.
[19] M. Tsimerman, D. Mallik, T. Matsuo, T. Otani, K. Tamao, M. G. Organ,
Chem. Commun., 2012, 48, 10352-10354.
a) R.E. Banks, B.E. Smart, J.C. Tatlow, Organofluorine Chemistry:
Principles and Commercial Applications, Plenum Press, New York, 1994;
b) H. Hiyama, Organofluorine Compounds: Chemistry and Applications,
Springer, Berlin, 2000; c) S. Purser, P.R. Moore, S. Swallow, V.
Gouverneur, Chem. Soc. Rev. 2008, 37, 320-330; d) P. Kirsch, Modern
Fluoroorganic Chemistry: Synthesis, Reactivity, Applications, second ed.,
Wiley-VCH, Weinheim, 2013; e) K. Müller, C. Faeh, F. Diederich,
Science 2007, 317, 1881-1886; f) F. Giornal, S. Pazenok, L. Rodefeld,
N. Lui, J.-P. Vors, F.R. Leroux, J. Fluorine Chem. 2013, 152, 2-11; g) J.
Wang, M. Sánchez-Roselló, J.L. Aceña, C. del Pozo, A.E. Sorochinsky,
S. Fustero, V.A. Soloshonok, H. Liu, Chem. Rev. 2014, 114, 2432-2506.
a) K. Uneyama, Organofluorine Chemistry, Blackwell, Oxford, UK, 2006;
b) M. Jagodzinska, F. Huguenot, G. Candiani, M. Zanda,
ChemMedChem, 2009, 4, 49-51.
[20] J. S. Kingsbury, J. P. A. Harrity, B. L. Gray, A. H. Hoveyda, J. Am. Chem.
Soc. 1999, 121, 791-799.
[21] T. Ritter, A. Hejl, A. G. Wenzel, T. W. Funk, R. H. Grubbs,
Organometallics, 2006, 25, 5740-5745.
[22] S. B. Garber, J. S. Kingsbury, B. L. Gray, A. H. Hoveyda, J. Am. Chem.
Soc. 2000, 122, 8168-8179.
[23] a) A. M. Lozano Vila, S. Monsaert, R. Drozdzak, S. Wolowiec, F.
Verpoort, Adv. Synth. Catal. 2009, 351, 2689-2701; b) M. Shao, L. Zheng,
W. Qiao, J. Wang, J. Wang, Adv. Synth. Catal., 2012, 354, 2743-2750;
c) G. Liu, L. Zheng, M. Shao, H. Zhang, W. Qiao, X. Wang, B. Liu, H.
Zhao, J. Wang, Tetrahedron 2014, 70, 4718-4725.
[6]
[7]
[8]
[24] J. Engel, W. Smit, M. Foscato, G. Occhipinti, K. W. Törnroos, V. R.
Jensen, J. Am. Chem. Soc., 2017, 139, 16609-16619.
a) M. Schlosser, Angew. Chem. Int. Ed. 1998, 37, 1496-1513; Angew.
Chem. 1998, 110, 1538-1556; b) D. O’Hagan, Chem. Soc. Rev. 2008,
37, 308-319.
[25] a) L. Falivene, R. Credendino, A. Poater, A. Petta, L. Serra, R. Oliva, V.
Scarano, L. Cavallo, Organometallics, 2016, 35, 2286-2293; b)
SambVca 2.0:
a web application for analyzing catalytic pockets.
a) R. C. Da Costa, J. A. Gladysz, Chem. Commun. 2006, 2619-2621; b)
R. C. Da Costa, J. A. Gladysz, Adv. Synth. Catal. 2007, 349, 243-254; c)
R. Tuba, R. C. Da Costa, H. S. Bazzi, J. A. Gladysz, ACS Catal. 2012, 2,
155-162; d) R. Tuba, E. N. Brothers, J. H. Reibenspies, H. S. Bazzi, J. A.
Gladysz, Inorg. Chem. 2012, 51, 9943-9949.
https://www.molnac.unisa.it/OMtools/sambvca2.0/.
[26] M. Barbasiewicz, M. Bieniek, A. Michrowska, A. Szadkowska, A. Makal,
K. Woźniak, K. Grela, Adv. Synth. Catal., 2007, 349, 193-203.
[27] A. M. Tsedilin, A. N. Fakhrutdinov, D. B. Eremin, S. S. Zalesskiy, A. O.
Chizhov, N. G. Kolotyrkina, V. P. Ananikov, Mend. Comm., 2015, 25,
454-456.
[9]
a) M. Matsugi, Y. Kobayashi, N. Suzumura, Y. Tsuchiya and T. Shioiri, J.
Org. Chem., 2010, 75, 7905-7908; b) J. Kvíčala, M. Schindler, V.
Kelbichova, M. Babunꢀk, M. Rybáčková, M. Kvičalova, J. Cvačka, A.
Bꢁezinova, J. Fluorine Chem., 2013, 153, 12-25; c) J. Lim, S. S. Lee, J.
Y. Ying, Chem. Commun., 2008, 4312-4314; d) Q. Yao, Y. Zhang, J. Am.
Chem. Soc., 2004, 126, 74-75; e) Y. Duan, T. Wang, Q. Xie, X. Yu, W.
Guo, J. Wang, G. Liu, Dalton Trans. 2016, 45, 19441-19448.
[10] a) L. Yang, M. Mayr, K. Wurst and M. R. Buchmeiser, Chem. Eur. J.,
2004, 10, 5761-5770; b) T. S. Halbach, S. Mix, D. Fischer, S. Maechling,
J. O. Krause, C. Sievers, S. Blechert, O. Nuyken, M. R. Buchmeiser, J.
Org. Chem., 2005, 70, 4687-4694; c) S. Monfette, K. D. Camm, S. I.
Gorelsky, D. E. Fogg, Organometallics, 2009, 28, 944-946.
[11] a) S. Fustero, A. Simón-Fuentes, P. Barrio, G. Haufe, Chem. Rev. 2015,
115, 871-930; b) V. Siano, I. d’Auria, F. Grisi, C. Costabile, P. Longo,
Cent. Eur. J. Chem. 2011, 9, 605-609; c) J. Hošek, M. Rybáčková, J.
Čejka, J. Cvačka, J. Kvíčala, Organometallics 2015, 34, 3327-3334.
[12] A. Fürstner, L. Ackermann, B. Gabor, R. Goddard, C. W. Lehmann, R.
Mynott, F. Stelzer, O. R. Thiel, Chem. Eur. J. 2001, 7, 3236-3253.
[13] a) T. Ritter, M. W. Day, R. H. Grubbs, J. Am. Chem. Soc. 2006, 128,
11768-11769; b) D. R. Anderson, D. J. O’Leary, R. H. Grubbs, Chem.
Eur. J. 2008, 14, 7536-7544.
[14] J. Hošek, O. ꢂimꢃnek, P. Lipovská, V. Kolaꢁíková, K. Kučnirová, A. Edr,
N. ꢂtꢀpánková, M. Rybáčková, J. Cvačka, J. Kvíčala ACS Sustainable
Chem. Eng., 2018, 6, 7026-7034.
[15] M. A. Topchiy, M. A. Zotova, S. M. Masoud, A. K. Mailyan, I. V. Ananyev,
S. E. Nefedov, A. F. Asachenko, S. N. Osipov, Chem. Eur. J. 2017, 23,
6663-6674.
[16] a) S. M. Masoud, A. K. Mailyan, V. Dorcet, T. Roisnel, P. H. Dixneuf, C.
Bruneau, S. N. Osipov, Organometallics, 2015, 34, 2305-2313; b) S. M.
Masoud, M. A. Topchiy, A. S. Peregudov, T. Roisnel, P. H. Dixneuf, C.
Bruneau, S. N. Osipov, J. Fluorine Chem. 2017, 200, 66-76; c) S. М.
Masoud, Т. R. Akmalov, О. I. Artyushin, C. Bruneau, S. N. Osipov, Russ.
Chem. Bull., 2017, 9, 1601-1606.
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Entry for the Table of Contents
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Salekh M. Masoud, Timur R. Akmalov,
Konstantin A. Palagin, Fedor M.
Dolgushin, Sergey E. Nefedov, Sergey
N. Osipov*
Page No. – Page No.
Ruthenium-alkylidene complexes
with sterically rigid fluorinated NHC
ligands
Novel ruthenium-alkylidene complexes with sterically rigid fluorinated NHC ligands
were synthesized and evaluated in representative olefin metathesis reactions. Along
with excellent robustness, they demonstrate remarkable activity in self-metathesis of
allylbenzene, outperforming commercially available Grubbs-Hoveyda catalyst in
terms of yield and regioselectivity.
Key Topic: metathesis catalysts
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