B.Ö. Öztürk et al. / Journal of Molecular Catalysis A: Chemical 376 (2013) 53–62
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7.14 (d, 1H, J = 9 Hz), 6.97 (t, 2H, J = 8 Hz). 13C NMR (75 MHz, DMSO):
165.54, 161.10, 158.14, 140.29, 135.90, 133.86, 133.17, 124.04,
119.82, 119.36, 117.58, 117.13, 115.65.
(m, PCy3 + n-pentane). 13C NMR (75 MHz, CDCl3): 177.52, 168.75,
154.80, 148.70, 136.81, 136.10, 135.00, 133.00, 129.05, 128.60,
128.00, 128.25, 125.45, 125.30, 123.21, 122.0, 119.45, 116.03,
110.99, 33.96, 33.70, 29.10, 29.41, 27.74, 27.63, 27.34, 27.00, 26.40,
26.35, 26.15, 22.37, 21.49. 31P NMR (161 MHz, CDCl3): 40.10. Ele-
mental analysis: found (calculated), C, 62.80 (62.72); N, 3.90 (3.85);
H, 6.47 (6.50).
2.2. Synthesis of thallium salts 2a–d
1a–d (13.0 mmol) were dissolved in 10 ml of dry THF, and thal-
lium ethoxide (26.0 mmol, 1.84 ml) was added under a nitrogen
atmosphere, and the reaction mixture was stirred for 2 h at room
temperature. The resulting solution was filtered and the thallium
salts isolated were used without further purification.
2.4. General procedure for the RCM reactions of
diethyldiallylmalonate with isolated complexes 3a, 3c and 3d
A
reactor was charged with 3d (0.025 g, 0.034 mmol)
2.3. Synthesis of ruthenium complexes 3a–d
and diethyldiallylmalonate (166.0 L, 0.69 mmol) in 2 ml
dichloromethane under an inert atmosphere of nitrogen. Reactor
was heated to 40 ◦C in an oil bath and HCl (1 M, 68 L) was
introduced into the reaction mixture. The reaction was followed
by GC–MS and 1H NMR analysis.
2.3.1. Synthesis of complex 3a
The Grubbs first generation catalyst (0.20 g, 0.24 mmol), 2a
(0.163 g, 0.26 mmol) and CuCl (0.26 mmol, 0.026 g) were weighed
into a Schlenk flask. The flask was evacuated and filled with nitro-
gen before the introduction of 10 ml of dry, degassed THF. The
mixture was stirred at room temperature for 20 min. The solvent
was removed under vacuum and the resulting crude solid product
was redissolved in a minimal amount of toluene, followed by filtra-
tion under high vacuum. The solvent volume was reduced in half
under vacuum, and then 5 ml of cold n-pentane was added to reac-
tion mixture. The resulting brown solids were filtered and washed
with cold n-pentane (Yield: 52–60%).
2.5. General procedure for the ROMP reactions of COE with
isolated complexes 3a, 3c and 3d
A reactor was charged with 3d (0.025 g, 0.034 mmol) and COE
(2.21 ml, 17 mmol) in 5 ml chlorobenzene under an inert atmo-
sphere of nitrogen. Reactor was heated to 40 ◦C in an oil bath and
HCl (1 M, 68 L) was introduced into the reaction mixture. Samples
were periodically drawn from reaction mixtures and monitored
by comparing the integrations of the olefinic monomer peak and
polymer peaks in 1H NMR. The reaction was quenched with addi-
tion of ethyl vinyl ether (130 L, 1.36 mmol) and stirred at room
temperature for 30 min. The polymer was precipitated by pouring
the resulting solution into an excess of methanol and collected by
filtration.
1H NMR (CDCl3, 400 MHz): 18.10 (d, 1H, J = 18 Hz), 8.55 (d, 1H,
J = 10 Hz), 7.57 (d, 1H, J = 7 Hz), 7.24 (d, 1H, J = 8 Hz), 7.19–7.05 (m,
5H, J = 9 Hz), 6.82 (t, 2H, J = 7 Hz), 6.65 (m, 3H, J = 8 Hz) 1.85–1.54 (m,
20H,), 1.40–1.11 (m, 10H). 13C NMR (CDCl3, 75 MHz): 171.5, 166.90,
155.5, 148.5, 138, 134.2, 131.6, 129.0, 128.2, 127.85, 127.70, 126.90,
125.20, 124.30, 122.10, 120.90, 119.0, 115.90, 115.81, 114.00, 33.40,
33.20, 29.10, 29.12, 27.90, 27.85, 26.90, 26.80, 26.50, 26.30, 26.10.
31P NMR (161 MHz, CDCl3): 40.15 ppm. Elemental analysis: found
(calculated), C, 66.99 (66.84); N, 2.09 (2.05); H, 7.20 (7.09).
2.6. General procedure for the in situ formation of 3a, 3c and 3d
A reactor was charged with G1 (0.025 g, 0.030 mmol), 2d
(0.021 g, 0.032 mmol), CuCl (0.0030 g, 0.030 mmol) in 1 ml THF and
reacted for 20 min until Grubbs 1st generation catalyst was com-
pletely converted to 3a–c. The formation of 3a–c was controlled
by 1H NMR analysis by taking aliquots from the reaction mixture.
After 20 min, the color of the solution turned to dark brown. This
solution was filtered to remove thallium(I) chloride before intro-
duction to a dichloromethane solution of diethyldiallylmalonate or
chlorobenzene solution of COE.
2.3.2. Synthesis of complex 3b
Our attempts to synthesize this compound failed because of
the formation of by-products. Although Complex 3b formed as
the major product in the isolated crude solid mixture, we could
not purify this complex using chromatographic methods. The 31P
NMR spectrum of the mixture consisted of signals coming from
Complex 3b (39.60 ppm), as well as unidentified non-alkylidene
by-products. The alkylidene proton peak appeared at 18.11 ppm
(d, 1H, J = 18 Hz) together with the imine proton at 8.60 ppm (d, 1H,
J = 10 Hz).
3. Results and discussion
2.3.3. Synthesis of complex 3c
This complex was synthesized using a similar procedure as used
to synthesize Complex 3a. (Brown solid, Yield: 55–60%). 1H NMR
(400 MHz, CDCl3): 18.10 (d, 1H, J = 14 Hz), 8.54 (d, 1H, J = 9 Hz), 7.76
(s, 1H), 7.66 (d, 1H, J = 8 Hz), 7.55 (d, 1H, J = 8 Hz) 7.43 (d, 1H, J = 8 Hz),
6.74 (m, 4H), 6.56 (t, 1H, J = 7 Hz), 2.33–0.90 (m, PCy3 + n-pentane).
13C NMR (75 MHz, CDCl3): 171.32, 168.75, 153.72, 149.30, 137.91,
136.42, 135.18, 129.05, 128.64, 128.40, 128.25, 125.95, 125.31,
123.81, 122.92, 119.70, 119.02, 115.99, 110.89, 33.96, 33.77, 29.13,
29.04, 27.74, 27.63, 27.34, 27.00, 26.40, 26.35, 26.15, 22.37, 21.49.
31P NMR (161 MHz, CDCl3): 40.26. Elemental analysis: found (cal-
culated), C, 62.83 (62.71); N, 3.88 (3.85); H, 6.62 (6.51).
We hypothesized that the Grubbs first generation catalyst can
be modified in situ by using tridentate Schiff base ligands (O
N O)
to obtain a latent and highly controllable catalyst system in a practi-
cal manner. We have chosen chelating tridentate Schiff base ligands
because they are easy to prepare and they exert electronic and steric
effects on the resulting complexes. To avoid metathesis activity at
both room temperature and high temperature, the imine group
must be in close proximity to the ruthenium center in order to
suppress the formation of a 14-electron metathesis-active species
by dissociation of the imine group. This approach is believed to
reduce the alkene binding to metal center using the current condi-
tions. Consequently, the catalyst/monomer mixture can be stored
at room temperature, as well as at relatively high temperatures
without any sign of polymerization. Moreover, this latency will
allow us to switch the catalytic activity on demand.
2.3.4. Synthesis of complex 3d
This complex was synthesized using a similar procedure as that
used to synthesize complex 3a. (Brown solid, Yield: 58–63%) 1H
NMR (400 MHz, CDCl3): 18.36 (d, 1H, J = 13 Hz), 8.86 (d, 1H, J = 9 Hz),
8.12 (d, 1H, J = 9 Hz), 7.46 (d, 1H, J = 8 Hz), 7.17 (d, 2H, J = 8 Hz),
7.10–7.00 (m, 5H), 6.76 (t, 1H, J = 7 Hz), 2.40 (s, 3H), 2.20–1.10
For this purpose, we have synthesized several tridentate
Schiff base ligands by condensation of salicylaldehyde with 2-
aminophenol derivatives with various substituents on the phenyl