Synthesis of pyrimidine-modified NHC ruthenium-alkylidene catalysts and their application in RCM, CM, em and ROMP reactions

Article abstract of DOI:10.1002/ejoc.201200989

A new type of N-heterocyclic carbene bearing ruthenium olefin metathesis catalyst was prepared through the incorporation of a chelated pyrimidinyl methylene subunit, in which electron-rich substituents were attached to stabilize the ruthenium complexes. These catalysts were successfully used in various types of olefin metathesis reactions, including ring-closing metathesis (RCM), cross-metathesis (CM), enyne metathesis (EM), and ring-opening metathesis polymerization (ROMP) reactions. The results therein showed that the presence of an electron-deficient pyrimidine structure greatly enhanced the new NHC ruthenium complexes' catalytic activities. New N-heterocyclic carbene bearing ruthenium olefin metathesis catalysts were synthesized and applied in various types of olefin metathesis reactions, including ring-closing metathesis, cross-metathesis, enyne metathesis, and ring-opening metathesis polymerization reactions. Copyright

Full text of DOI:10.1002/ejoc.201200989

FULL PAPER
DOI: 10.1002/ejoc.201200989
Synthesis of Pyrimidine-Modified NHC Ruthenium-Alkylidene Catalysts and
Their Application in RCM, CM, EM and ROMP Reactions
Guang-Long Wu,[a,b] Sheng-Li Cao,*[a] Jian Chen,*[b] and Zili Chen*[c]
Keywords: Synthetic methods / Homogeneous catalysis / Ruthenium / Nitrogen heterocycles / Metathesis
A new type of N-heterocyclic carbene bearing ruthenium
olefin metathesis catalyst was prepared through the incorpo-
ration of a chelated pyrimidinyl methylene subunit, in which
electron-rich substituents were attached to stabilize the ru-
thenium complexes. These catalysts were successfully used
in various types of olefin metathesis reactions, including
ring-closing metathesis (RCM), cross-metathesis (CM), en-
yne metathesis (EM), and ring-opening metathesis polymeri-
zation (ROMP) reactions. The results therein showed that the
presence of an electron-deficient pyrimidine structure
greatly enhanced the new NHC ruthenium complexes’ cata-
lytic activities.
more slowly than highly-active catalyst 1 as a result of steric
(large isopropoxy group) and electronic factors (iPrO to ru-
thenium electron donation). Based on these findings, sig-
nificant effort has been devoted to develop stable and active
new catalysts through modifying the benzylidene unit or
chelated isopropoxy fragment of complex 2.[5–7]
Introduction
The development of powerful air-stable catalysts has
made olefin metathesis an indispensable tool in a variety
of fields including organic synthesis, materials science, and
biochemistry.[1] Among multiple metal-based complexes en-
abling olefin metathesis transformations, ruthenium-benzyl-
In order to enhance the leaving ability of the benzylidene
idene pre-catalysts bearing N-heterocyclic carbene (NHC) ligand, complex 3 was reported by Blechert group, which
ligands exhibited extraordinary activity and stability.[2] increased the neighboring steric bulk of the isopropoxy
Mechanistic studies upon the NHC-complexed ruthenium- group (Figure 1).[6] Almost at the same time, the Grela
benzylidene pre-catalysts 1 (Figure 1) revealed that a low group developed complex 4 through a different approach,
ratio of phosphane reassociation to substrate binding was in which an electron-withdrawing nitro group was intro-
necessary for its high activity.[3] In 2000, phosphane-free duced to reduce the benzylidene unit’s chelating ability
NHC complex 2 (Grubbs-Hoveyda catalyst) was developed, (Figure 1), thus facilitating formation of the catalytically
in which, a chelating benzylidene structure (Figure 1) pro- active 14-electron Ru carbene species, and suppressing re-
vided superior stability.[4] However, this catalyst initiates peated reassociation to the metal center.[7] We herein want
Figure 1. Ruthenium metathesis catalysts.
to report a new variant of complex 2 in which we replace
[a] Department of Chemistry, Capital Normal University,
the phenyl group with an electron-deficient pyrimidine unit
(complex 5, Figure 1). We envisioned that the presence of
the electron-deficient pyrimidine group would also improve
the ruthenium complex’s reactivity. Additionally, the ease
of introducing functionality between the two nitrogen
atoms in complex 5 might provide new possibilities in the
design of new types of ruthenium olefin-metathesis cata-
Beijing 100048, P. R. China
E-mail: slcao@cnu.edu.cn
Homepage: http://202.204.208.66/hxx/index.php?q=node/207
[b] Bioduro (Beijing) Co. Ltd.,
Beijing 102206, P. R. China
[c] Department of Chemistry, Renmin University of China,
Beijing 100872, P. R. China
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201200989.
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G.-L. Wu, S.-L. Cao, J. Chen, Z. Chen
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lysts. In previous reports, a heterocyclic pyridine group has reaction of compound 9 with iPrONa (2 equiv.). Stille cou-
been used as a complexing ligand in phosphane-free ruthe- pling of 7b provided 8b in 84% yield. But the effort to syn-
nium catalysts.[8] However, this is the first report, to the best thesize 5b from 8b was fruitless.
of our knowledge, of incorporating a chelating heterocyclic
unit into the alkylidene unit in NHC-ruthenium complexes
(Figure 1).
We considered that a more electron-rich pyrimidinyl-
methylene subunit would stabilize the ruthenium complex.
Therefore, electron-rich amino substituents bearing vinyl-
pyrimidine derivatives 8c–e were designed. Treating 9 with
iPrONa (1 mol equiv.), followed by piperidine attachment
readily afforded 4-isopropoxy-2-piperidiny-5-vinylpyrimi-
dine (7c) in 85% yield. Compound 8c, synthesized from 7c
through a Stille coupling, reacted with complex 1 in CH2Cl2
by using CuCl as a scavenger, giving pyrimidine-modified
NHC ruthenium-alkylidene complex 5c in 75% yield. Simi-
larly, complexes 5d and 5e were also prepared in moderate
to good yields through four step reactions (Scheme 1).
A symmetric dimeric pyrimidine-modified NHC ruthe-
nium-alkylidene 5f was then synthesized by using pipera-
zine as the bridge. Successive treatment of 9 with iPrONa
(1 mol equiv.) and piperazine (0.5 mol equiv.) gave 7f in
91% yield. Subsequent vinyl coupling and complexation
with ruthenium afforded dimeric complex 5f in 72% yield
(Scheme 1).
Results and Discussion
A variety of vinylpyrimidine derivatives 8a–f have been
designed for the preparation of the pyrimidine-modified
NHC ruthenium-alkylidene complexes 5. Our synthetic
routes started from commercially available 5-bromopyrim-
idin-4(3H)-one (6) and 5-bromo-2,4-dichloropyrimidine (9).
As shown in Scheme 1, treating compound 6 with POCl3
under reflux conditions gave its 4-chloro analogue, which
then reacted with iPrONa in THF at low temperature to
provide 7a in 90% yield (2 steps). Stille coupling of 7a with
tributylvinyltin by using palladium catalysis in a mixture of
dioxane/H2O afforded 4-isopropoxy-5-vinylpyrimidine (8a)
in 89% yield. However, the reaction of 8a with complex 1
in CH2Cl2 gave no desired pyrimidine-modified NHC ru-
thenium-alkylidene 5a, possibly owing to its instability.[9,10]
The structures of complexes 5c–f were all characterized
We then turned to synthesize 2,4-diisopropoxy-5-vinyl- from their 1H NMR and 13C NMR spectroscopic data and
pyrimidine (8b). Its bromo precursor 7b was prepared from element analyses.
Scheme 1. Preparation of catalysts 5c–f. Reagents and conditions: (a) POCl3, reflux, 2 h. (b) THF, iPrONa (1.0 equiv.), –20 °C to r.t.
(c) CH2=CHSnBu3 (1.5 equiv.), Pd(dppf)Cl2 (5mol-% equiv.), dioxane/H2O (5:1), 60 °C, overnight. (d) 1 (1.05 equiv.), CuCl (3.0 equiv.),
CH2Cl2, reflux, 1 h. (e) THF, iPrONa (2.0 equiv.), –20 °C to r.t.. (f) RH (3.0 equiv.), 60 °C, 6 h. (g) Piperazine (0.5 equiv.), 60 °C, 6 h.
(h) CH2=CHSnBu3 (3 equiv.), Pd(dppf)Cl2 (0.1 equiv.), dioxane, H2O, 60 °C, overnight. (i) 1 (2.1 equiv.), CuCl (6.0 equiv.), CH2Cl2, reflux,
1 h.
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NHC Ruthenium-Alkylidene Catalysts
Having these new complexes in hand, we started to ex- Table 1. Low-catalyst-loading experiment.[a,b]
plore their relative catalytic activities. RCM reaction of di-
allyltosylamide (10a) was chosen as the model system for
our initial investigation. All representative results are col-
lected in Figure 2. As shown in Figure 2, the difference be-
tween the catalytic activities of complexes 5c, 5e and 5f were
minimal. Complex 5d exhibited the lowest activity, whereas
5c and 5f showed better activities. Although the activities
of 5c–f were lower than that of catalyst 4, complexes 5c–f
were dramatically more active than parent Hoveyda catalyst
2. Interestingly, bis-ruthenium complex 5f (0.5 mol-% of 5f)
initializes the reaction visibly faster than mono-ruthenium
5c, 5d and 5e (1.0 mol-%; Figure 2).
[a] Unless noted, all reactions were performed in CH2Cl2 at 25 °C
and the catalyst loading ranged from 1.0% to 0.2% (based on ru-
thenium metal concentration). [b] Reaction time: 1 h for 1.0% cata-
lyst loading, 2 h for 0.5% and 4 h for 0.2%. [c] Yields were deter-
mined by GC. [d] Isolated yields. [e] The percentage recovery of
catalysts 5c–f: 5c, 74%; 5d, 68%; 5e, 71%; 5f, 27%.
Table 2. Catalysts 5c, 5d, 5e and 5f in RCM and EM reactions.[a]
Figure 2. Relative rates of diene 10a’s RCM reaction with catalysts
2, 5c, 5d and 5e (1 mol-%), and 5f (0.5 mol-%). (diamond: catalyst
2, square: catalyst 4, triangle: catalyst 5c, cross: 5d, asterisk: 5e,
circle: 5f).
In order to further explore the complexes’ catalytic ac-
tivities, a series of low-catalyst-loading experiments were
performed. RCM reactions of diene substrates 10a, 10d, 10f
and 10g were tested, in which four carbo- or heterocyclic
molecules 11 were obtained. As shown in Table 1, three
levels of catalyst loading (1 mol-%, 0.5 mol-% and 0.2 mol-
% based on ruthenium metal concentration) were tested.
When 1 mol-% of catalyst was utilized, all reactions were
complete in 1 h, giving the desired product in quantitative
yields (Table 1, Entries 1, 4, 7 and 10). When 0.5 mol-% of
catalyst was added, high reaction yields were obtained in
2 h (Table 1, Entries 2, 5, 8 and 11). However, when
0.2 mol-% of catalyst was added, the reaction yields de-
creased significantly, even after a longer reaction time
(Table 1, Entries 3, 6, 9 and 12).
Encouraged by previous results, metathesis reactions of
various diene or enyne substrates were then examined and
representative results are shown in Table 2. As illustrated in
Table 2, complexes 5c–e served as effective catalysts for the
formation of di- and trisubstituted five-, six-, and seven-
[a] Unless noted, all reactions were performed in CH2Cl2 and the
catalyst loading ranged from 4.0% to 0.25% (based on ruthenium
metal concentration). [b] Yields were determined by GC. [c] Iso-
lated yields. [d] Decomposition of complexes 5c–f were observed at
membered cyclic molecules from TsN- or malonate-bridged a high temperature.
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G.-L. Wu, S.-L. Cao, J. Chen, Z. Chen
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Table 3. Catalysts 5c and 5f in intermolecular cross-metathesis reaction.[a]
[a] Unless noted, all reactions were performed in CH2Cl2 for 2 h and the catalyst loading ranged from 1.0% to 4.0% (based on ruthenium
metal concentration). [b] Yields were calculated from GC data. [c] Isolated yields. [d] Reaction time is 5 h.
substrates (Table 2, Entries 1–3, 5–7). The corresponding
We studied the catalytic activity of the new pyrimidine-
products were obtained in excellent yields at room tempera- bearing complexes in the ROMP of norbornene (14) by
1
ture. In the reaction of diisobutenyl tosylamide substrate means of H NMR spectroscopy monitoring (Table 4). It
10e, tetrasubstituted olefin product 11e was obtained in was found that ROMP reactions of 14 were complete in
moderate yields in 5 h at an elevated temperature (Table 2, 30 min with catalysts 5c–f with catalyst loadings as low as
Entry 5). Enyne metathesis reaction of 10g and 10h af- 0.5 mol-% (based on ruthenium concentration). The
forded 11g and 11h in excellent yields at room temperature cis/trans ratio of polymer 15 was similar to Grubbs’ re-
(Table 2, Entries 7 and 8). In addition, double-enyne me- sult.[11,12]
tathesis reaction of dienyne substrate 10i gave 3,3Ј-bipyrrole
11i in moderate to good yields (Table 2, Entry 9). Relative
to the results reported by the Grela group with catalyst 4,
Table 4. ROMP reactions of norbornene (14) with catalysts 5c, 5d,
5e and 5f.[a]
complexes 5c–e performed better in RCM reactions of
10g.[7]
We then turned to investigate the intermolecular CM re-
actions of various substrates by using 5c and 5f as catalysts
(Table 3). In CM reactions of 12a (1 mol equiv.) with other
alkenes (2 mol equiv.), including electron-deficient acrylate
12b, electron-rich 2-butene-1,4-diacetate 12d, allylamine
substrate 12e and styrene (12f), unsymmetrical disubsti-
tuted olefin products 13c–f were obtained in good to excel-
lent yields with a high degree of E-selectivity. Whereas in
the reaction of 12a with acrylonitrile 12c, low to moderate
yields and poor E/Z selectivity were observed, the CM reac-
[a] Unless noted, all reactions were performed in CH2Cl2 with
0.5 mol-% catalyst (based on ruthenium metal concentration).
[b] Yield and cis/trans ratio were determined by means of NMR
spectroscopy.
tion of 12f with 12d, E-configuration cinnamyl acetate (13f)
was obtained in high yield.
The air stabilities of complexes 5c–f were also tested. As
shown in Table 5, the catalytic activities of 5c–f remained
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NHC Ruthenium-Alkylidene Catalysts
recorded in CDCl3, with proton and carbon resonances at 300 and
75 MHz, respectively, and are referenced to the residual solvent
signal at δ = 7.26 ppm for 1H and δ = 77.36 ppm for 13C. Data for
1H are reported as follows: chemical shift (δ ppm), multiplicity (s
= singlet, d = doublet, t = triplet, q = quartet, m = multiplet, sept
= septet), coupling constant and integration. Data for 13C NMR
are reported in terms of chemical shift.
the same after 10 to 30 d air-storage, which indicates that
complexes 5c–f are quite stable.
Table 5. Stability study of the catalysts.[a]
5-Bromo-4-isopropoxypyrimidine (7a): A solution of 5-bromopyrim-
idin-4(3H)-one (6) (2 g, 11.5 mmol) in POCl3 (10 mL) was heated
to reflux for 2 h. After removal of the solvent, the residue was dis-
solved in THF (5 mL). A solution of sodium isopropanoxide
(11.5 mmol, 1.0 equiv.) in anhydrous 2-propanol (20 mL) was then
added dropwise at –20 °C under a N2 atmosphere. After 1 h, the
reaction mixture slowly warmed to room temperature. Concentra-
tion and purification with SiO2 (eluant ethyl ether) afforded com-
pound 7a as a colorless oil (2.25 g, 90% yield). 1H NMR
(300 MHz, CDCl3): δ = 8.69 (br. s, 2 H, aromatic H), 5.42 [sept, J
= 6.3 Hz, 1 H, (CH3)2CHO], 1.42 [d, J = 6.3 Hz, 6 H, (CH3)2-
CHO] ppm. 13C NMR (75 MHz, CDCl3): δ = 164.73, 158.22,
156.44, 90.05, 71.67, 22.14 ppm. MS (ESI): m/z = 217, 219 [M +
H]+. HRMS (ESI): calcd. for C7H1079BrN2O [M + H]+ 216.9977;
found 216.9983.
[a] The catalysts were kept in air at room temperature. Unless
noted, all reactions were performed in CH2Cl2 with 0.5 mol-% cata-
lyst (based on ruthenium metal concentration). [b] Yields were de-
termined by means of GC–MS analysis.
One of the unique properties of Hoveyda–Grubbs carb-
ene 2 is that up to 95% of the catalyst can be recovered
after the reaction.[4] We also attempted to recover the cata-
lysts in the RCM reactions of 10a (Table 1, Entry 1). It was
found that 5c, 5d, 5e and 5f could be recovered with good
to moderate efficiency (74–27%, Table 1 footnote), whereas
high temperatures and longer reaction times (Table 2, En-
tries 5 and 9) lead to decomposition of 5c–f.
5-Bromo-2,4-diisopropoxypyrimidine (7b): To a solution of 5-
bromo-2,4-dichloropyrimidine (9, 2.5 g, 11.5 mmol) in THF
(100 mL) was added
a solution of sodium isopropanoxide
(22 mmol, 2.0 equiv.) in anhydrous 2-propanol (50 mL) dropwise at
–20 °C under a N2 atmosphere. After 1 h, the reaction mixture
slowly warmed to room temperature. The routine work-up pro-
1
cedure afforded 7b as a colorless oil (3.04 g, 96% yield). H NMR
(300 MHz, CDCl3): δ = 8.26 (s, 1 H, aromatic H), 5.41 [sept, J =
6.3 Hz, 1 H, (CH3)2CHO], 5.18 [sept, J = 6.3 Hz, 1 H, (CH3)2-
CHO], 1.40–1.37 [m, 12 H, (CH3)2CHO] ppm. 13C NMR (75 MHz,
CDCl3): δ = 166.20, 163.53, 159.38, 98.25, 71.45, 71.29, 22.29,
22.25 ppm. MS (ESI): m/z = 275, 277 [M + H]+. HRMS (ESI):
calcd. for C10H1679BrN2O2 [M + H]+ 275.0395; found 275.0379.
Conclusions
In conclusion, a series of pyrimidine-modified NHC ru-
thenium-alkylidene complexes 5c–f were prepared through
the reaction of complex 1 with pyrimidine derivatives 8c–f.
Electron-rich 2-substituents, such as morpholinyl-, piperazi-
nyl- and tosyl-piperazinyl groups, were attached to enhance
these complexes’ stabilities. All these complexes exhibited
good air-stability and excellent catalytic activity[13] in me-
tathesis reactions of dienes or enynes, and also in CM reac-
tions and ROMP reactions. Considering its simple prepara-
tion, high activity and excellent stability, the preparation
of new pyrimidine NHC ruthenium-alkylidene complexes
could provide an attractive new approach to develop practi-
cal olefin metathesis catalysts.
5-Bromo-4-isopropoxy-2-(morpholin-1-yl)pyrimidine (7c): To a solu-
tion of 5-bromo-2,4-dichloropyrimidine (9, 5 g, 21.9 mmol) in THF
(100 mL) was added
a solution of sodium isopropanoxide
(21.9 mmol, 1.0 equiv.) in anhydrous 2-propanol (50 mL) dropwise
at –20 °C under a N2 atmosphere. After 1h, the reaction mixture
slowly warmed to room temperature. Then, morphiline (1.9 g,
21.9 mmol) was slowly added. The reaction mixture was heated at
60 °C for 3 h. Concentration and purification with SiO2 (eluant
1
diethyl ether) afforded 7c as a white solid (5.63 g, 85% yield). H
NMR (300 MHz, CDCl3): δ = 8.12 (s, 1 H, aromatic H), 5.30 [sept,
J = 6.3 Hz, 1 H, (CH3)2CHO], 3.75–3.72 (m, 8 H, morpholinyl H),
1.38 [d, J = 6.3 Hz, 6 H, (CH3)2CHO] ppm. 13C NMR (75 MHz,
CDCl3): δ = 164.58, 160.44, 158.67, 93.27, 70.51, 67.03, 44.84,
22.19 ppm. MS (ESI): m/z = 302, 304 [M + H]+. C11H16BrN3O2
(302.17): calcd. C 43.72, H 5.34, N 13.91; found C 44.33, H 5.26,
N 13.84. HRMS (ESI): calcd. for C11H1779BrN3O2 [M + H]+
302.0504; found 302.0493.
Experimental Section
General: Unless otherwise noted, all reactions were performed un-
der an inert atmosphere (N2) with flame-dried glassware using stan-
dard techniques for manipulating air-sensitive compounds. The sol-
vents were dried by distillation over the following drying agents:
THF (Na/benzophenone), toluene (Na), n-pentane, n-hexane,
CH2Cl2 (CaH2), Et2O (LiAlH4), MeOH (Mg). All commercial rea-
gents were used as received or purified by standard techniques
where necessary. Column chromatography was performed using
200–300 mesh silica with the proper solvent system according to
TLC analysis using KMnO4 stain and UV light to visualize the
reaction components. Unless otherwise noted, NMR spectra were
5-Bromo-4-isopropoxy-2-(piperidin-1-yl)pyrimidine (7d): By using
the same method as for the synthesis of 7c, compound 7d was ob-
tained as a colorless oil (6.05 g, 92% yield). H NMR (300 MHz,
CDCl3): δ = 8.09 (s, 1 H, aromatic H), 5.30 [sept, J = 6.3 Hz, 1 H,
(CH3)2CHO], 3.72–3.68 (m, 4 H, CH2NCH2), 1.64–1.57 (m, 6 H,
CH2CH2CH2), 1.38 [d, J = 6.3 Hz, 6 H, (CH3)2CHO] ppm. 13C
NMR (75 MHz, CDCl3): δ = 164.30, 160.38, 158.73, 91.75, 70.12,
45.50, 26.06, 25.21, 22.21 ppm. MS (ESI): m/z = 299, 301 [M]+.
HRMS (EI): calcd. for C12H18BrN3O 299.0633, 301.0613; found
299.0634, 301.0617.
1
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5-Bromo-4-isopropoxy-2-(4-tosylpiperazin-1-yl)pyrimidine (7e): By
using the same method as for the synthesis of 7c, compound 7e was
obtained as a white solid (8.29 g, 83% yield). H NMR (300 MHz,
as a colorless oil (1.39 g, 84% yield). 1H NMR (300 MHz, CDCl3):
δ = 8.13 (s, 1 H, aromatic H), 6.57 (dd, J = 17.7, 11.4 Hz, 1 H,
ArCH=CH2), 5.68 (dd, J = 17.7, 1.5 Hz, 1 H, ArCH=CH2), 5.34
[sept, J = 6.3 Hz, 1 H, (CH3)2CHO], 5.07 (dd, J1 = 11.4, 1.5 Hz, 1
H, ArCH=CH2), 3.77–3.73 (m, 4 H, piperidinyl H), 1.66–1.58 (m,
6 H, piperidinyl H), 1.38 [d, J = 6.3 Hz, 6 H, (CH3)2CHO] ppm.
13C NMR (75 MHz, CDCl3): δ = 166.04, 160.47, 156.25, 129.35,
1
CDCl3): δ = 8.04 (s, 1 H, aromatic H), 7.64 (d, J = 8.4 Hz, 2 H,
aromatic H), 7.32 (d, J = 8.4 Hz, 2 H, aromatic H), 5.23 [sept, J =
6.3 Hz, 1 H, (CH3)2CHO], 3.85 (t, J = 4.8 Hz, 4 H, piperazinyl H),
3.02 (t, J = 4.8 Hz, 4 H, piperazinyl H), 2.41 (s, 3 H, CH3Ph), 1.35
[d, J = 6.3 Hz, 6 H, (CH3)2CHO] ppm. 13C NMR (75 MHz, 111.84, 107.50, 68.92, 45.42, 26.22, 25.41, 22.46 ppm. MS (ESI):
CDCl3): δ = 164.55, 159.86, 158.74, 144.08, 132.51, 129.97, 127.99, m/z = 247 [M]+. HRMS (EI): calcd. for C14H21N3O [M]+ 247.1685;
93.46, 70.55, 46.15, 43.69, 22.13, 21.95 ppm. MS (ESI): m/z = 455,
457 [M + H]+. C18H23BrN4O3S (455.37): calcd. C 47.48, H 5.09, N
12.30; found C 47.30, H 5.05, N 12.02.
found 247.1687.
4-Isopropoxy-2-(4-tosylpiperazin-1-yl)-5-vinylpyrimidine (8e): By
using the same method as for the synthesis of 8a, compound 8e was
obtained as a white solid (1.51 g, 85% yield). H NMR (300 MHz,
1
1,4-Bis(5-bromo-4-isopropoxypyrimidin-2-yl)piperazine (7f): By
using the same method as for the synthesis of 7c, compound 7f was
CDCl3): δ = 8.07 (s, 1 H, aromatic H), 7.64 (d, J = 8.1 Hz, aromatic
H), 7.32 (d, J = 8.1 Hz, aromatic H), 6.53 (dd, J = 17.7, 11.4 Hz,
1 H, ArCH=CH2), 5.68 (dd, J = 17.7, 1.5 Hz, 1 H, ArCH=CH2),
5.28 [sept, J = 6.3 Hz, 1 H, (CH3)2CHO], 5.10 (dd, J = 11.4, 1.5 Hz,
1 H, ArCH=CH2), 3.89 (t, J = 5.1 Hz, 4 H, piperazinyl H), 3.03
(t, J = 5.1 Hz, 4 H, piperazine H), 2.41 (s, 3 H, PhCH3), 1.34 [d, J
= 6.3 Hz, 6 H, (CH3)2CHO] ppm. 13C NMR (75 MHz, CDCl3): δ
= 166.24, 159.99, 156.11, 144.04, 132.56, 129.96, 128.92, 128.02,
113.09, 108.90, 69.30, 46.25, 43.59, 22.32, 21.95 ppm. MS (ESI):
m/z = 403 [M + H]+. C20H26N4O3S (402.51): calcd. C 59.68, H
6.51, N 13.92; found C 59.46, H 6.46, N 13.81.
1
obtained as a white solid (5.12 g, 91% yield). H NMR (300 MHz,
CDCl3): δ = 8.13 (s, 2 H, aromatic H), 5.32 [sept, J = 6.3 Hz, 2 H,
(CH3)2CHO], 3.81 (s, 8 H, piperazinyl H), 1.40 [d, J = 6.3 Hz, 12
H, (CH3)2CHO] ppm. 13C NMR (75 MHz, CDCl3): δ = 164.56,
160.40, 158.79, 93.13, 70.50, 44.15, 22.22 ppm. MS (ESI): m/z =
517 [M + H]+. C18H24Br2N6O2 (516.23): calcd. C 41.88, H 4.69, N
16.28; found C 41.83, H 4.68, N 16.11.
4-Isopropoxy-5-vinylpyrimidine (8a): To a solution of 7a (2.00 g,
9.22 mmol) in a mixture of dioxane (30 mL) and water (6 mL), was
added tributyl(vinyl)stannane (4.38 g, 13.82 mmol, 1.5 equiv.),
Pd(dppf)Cl2 (337 mg, 0.46 mmol, 0.05 equiv.) and K2CO3 (2.55 g,
18.44 mmol, 2 equiv.). After stirring at 60 °C overnight under a N2
atmosphere, the reaction mixture was filtered through a short pad
of silica gel (1ϫ5 cm) and washed with ethyl acetate (3ϫ50 mL).
Removal of the solvent and purification with SiO2 (eluant 5% ethyl
acetate/petroleum ether) afforded 8a as a colorless oil (1.35 g, 89%
yield). 1H NMR (300 MHz, CDCl3): δ = 8.61 (s, 1 H, aromatic
H), 8.47 (s, 1 H, aromatic H), 6.70 (dd, J = 17.7, 11.4 Hz, 1 H,
ArCH=CH2), 5.96 (dd, J = 17.7, 1.5 Hz, 1 H, ArCH=CH2), 5.50–
5.38 [m, 2 H, ArCH=CH2, (CH3)2CHO], 1.39 [d, J = 6.0 Hz, 6 H,
(CH3)2CHO] ppm. 13C NMR (75 MHz, CDCl3): δ = 167.80,
160.19, 156.97, 154.49, 128.55, 118.55, 70.08, 22.19 ppm. MS (ESI):
m/z = 165 [M + H]+. HRMS (ESI): calcd. for C9H13N2O
[M + H]+ 165.1028; found 165.1030.
1,4-Bis(4-isopropoxy-5-vinylpyrimidin-2-yl)piperazine (8f): By using
the same method as for the synthesis of 8a, compound 8f was ob-
tained as a white solid (0.96 g, 60% yield). 1H NMR (300 MHz,
CDCl3): δ = 8.16 (s, 2 H, aromatic H), 6.58 (dd, J = 17.7, 11.4 Hz,
2 H, ArCH=CH2), 5.72 (dd, J = 17.7, 0.9 Hz, 2 H, ArCH=CH2),
5.37 [sept, J = 6.0 Hz, 2 H, (CH3)2CHO], 5.12 (dd, J = 11.4, 0.9 Hz,
2 H, ArCH=CH2), 3.87 (s, 8 H, piperazinyl H), 1.40 [d, J = 6.0 Hz,
12 H, (CH3)2CHO] ppm. 13C NMR (75 MHz, CDCl3): δ = 166.26,
160.63, 156.26, 129.18, 112.72, 108.57, 69.21, 44.17, 22.40 ppm. MS
(ESI): m/z = 411 [M + H]+. C22H30N6O2·1/2H2O: calcd. C 62.99,
H 7.45, N 20.03; found C 63.27, H 7.31, N 19.47.
[4-OiPr-5-(4,5-dihydroIMES)Cl2Ru=CH]pyrimidin-2-ylmorpholine
(5c): To a solution of 8c (29 mg, 0.117 mmol), CuCl (35 mg,
0.35 mmol, 3.00 equiv.) in CH2Cl2 (10 mL), was added (4,5-Dihy-
droIMES)-(PCy3 )Cl2 Ru=CHPh (1, 105 mg, 0.12 mmol,
1.05 equiv.) at 25 °C under a N2 atmosphere. The reaction mixture
was heated to reflux at 40 °C for 1 h. After removal of the solvent,
the residue was dissolved in pentane/CH2Cl2 (1:1, 2 mL) and fil-
tered through cotton to remove the copper-phosphane precipitate.
Further concentration and purification with SiO2 afforded 5c as a
2,4-Diisopropoxy-5-vinylpyrimidine (8b): By using the same method
as for the synthesis of 8a, compound 8b was obtained as a colorless
1
oil (1.36 g, 84% yield). H NMR (300 MHz, CDCl3): δ = 8.24 (s,
1 H, aromatic H), 6.62 (dd, J = 17.7, 11.4 Hz, 1 H, ArCH=CH2),
5.79 (dd, J = 17.7, 1.5 Hz, 1 H, ArCH=CH2), 5.45 [sept, J =
6.3 Hz, 1 H, (CH3)2CHO], 5.27–5.19 [m, 2 H, (CH3)2CHO,
ArCH=CH2], 1.38 [d, J = 6.0 Hz, 6 H, (CH3)2CHO], 1.36 [d, J =
6.3 Hz, 6 H, (CH3)2CHO] ppm. 13C NMR (75 MHz, CDCl3): δ =
167.56, 156.52, 128.47, 115.11, 112.83, 100.47, 70.51, 69.98, 22.41,
22.37 ppm. MS (ESI): m/z = 223 [M + H]+. HRMS (ESI): calcd.
for C12H19N2O2 [M + H]+ 223.1447; found 223.1442.
1
green solid (58 mg, 69% yield). H NMR (300 MHz, CDCl3): δ =
15.86 (s, 1 H, Ru=CHAr), 7.80 (s, 1 H, aromatic CH), 7.05 (s, 4
H, mesityl aromatic CH), 5.40–5.32 [m, 1 H, (CH3)2CHOAr], 4.17
[s, 4 H, N(CH2)2N], 3.76–3.67 (m, 8 H, morpholinyl H) 2.46 (s, 12
H, mesityl o-CH3), 2.37 (s, 6 H, mesityl p-CH3), 1.26 [d, J = 6.0 Hz,
6 H, (CH3)2CHOAr] ppm. 13C NMR (75 MHz, CDCl3): δ =
297.06, 211.46, 165.06, 160.20, 149.61, 138.98, 129.90 129.48,
75.98, 66.89, 51.81, 45.22, 21.72, 21.56 ppm. C33H43Cl2N5O2Ru
(713.71): calcd. C 55.53, H 6.07, N 9.81; found C 55.23, H 6.08, N
9.59.
4-Isopropoxy-2-(morpholin-1-yl)-5-vinylpyrimidine (8c): By using
the same method as for the synthesis of 8a, compound 8c was ob-
1
tained as a colorless oil (1.31 g, 79% yield). H NMR (300 MHz,
CDCl3): δ = 8.15 (s, 1 H, aromatic H), 6.58 (dd, J = 17.7, 11.4 Hz,
1 H, ArCH=CH2), 5.72 (dd, J = 17.7, 1.5 Hz, 1 H, ArCH=CH2),
5.34 [sept, J = 6.3 Hz, 1 H, (CH3)2CHO], 5.12 (dd, J = 11.4, 1.5 Hz,
1 H, ArCH=CH2), 3.76 (s, 8 H, morpholinyl H), 1.38 [d, J =
6.3 Hz, 6 H, (CH3)2CHO] ppm. 13C NMR (75 MHz, CDCl3): δ =
166.25, 160.66, 156.17, 129.14, 112.84, 108.76, 69.22, 67.15, 44.76,
22.38 ppm. MS (ESI): m/z = 249 [M]+. HRMS (EI): calcd. for
C13H19N3O2 249.1477; found 249.1480.
[4-OiPr-5-(4,5-dihydroIMES)Cl2Ru=CH]pyrimidin-2-ylpiperidine
(5d): By using the same method as for the synthesis of 5c, com-
pound 5d was obtained as a green solid (63 mg, 75% yield). 1H
NMR (300 MHz, CDCl3): δ = 15.79 (s, 1 H, Ru=CHAr), 7.77 (s,
1 H, aromatic H), 7.04 (s, 4 H, mesityl aromatic H), 5.40–5.32 [m,
1 H, (CH3)2CHOAr], 4.17 [s, 4 H, N(CH2)2N], 3.73 [s, 4 H, piperid-
inyl ArN(CH2)2] 2.46 (s, 12 H, mesityl o-CH3), 2.36 (s, 6 H, mesityl
p-CH3), 1.65–1.52 [m, 6 H, piperidinyl (CH2)3], 1.26 [d, J = 6.3 Hz,
4-Isopropoxy-2-(piperidin-1-yl)-5-vinylpyrimidine (8d): By using the
same method as for the synthesis of 8a, compound 8d was obtained
6782
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 6777–6784

NHC Ruthenium-Alkylidene Catalysts
6 H, (CH3)2CHOAr] ppm. 13C NMR (75 MHz, CDCl3): δ = 1-Tosyl-1,2,3,6-tetrahydropyridine (11b):[15] White solid. 1H NMR
287.68, 212.44, 165.11, 160.22, 149.99, 138.86, 129.42, 128.95, (300 MHz, CDCl3): δ = 7.65 (d, J = 8.1 Hz, 2 H), 7.31 (d, J =
75.56, 51.78, 46.09, 26.12, 25.12, 22.37, 21.65, 21.49 ppm. 8.1 Hz, 2 H), 5.70–5.58 (m, 2 H), 3.54 (d, J = 5.4 Hz, 2 H), 3.17
C34H45Cl2N5ORu + H2O: calcd. C 55.96, H 6.49, N 9.60; found C
55.56, H 6.35, N 9.21.
(t, J = 5.7 Hz, 2 H), 2.40 (s, 3 H), 2.18–2.17 (m, 2 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 143.63, 133.26, 129.75, 127.77,
125.15, 122.83, 45.07, 42.94, 25.56, 21.85 ppm. MS (ESI): m/z =
238 [M + H]+.
[4-OiPr-5-(4,5-dihydroIMES)Cl2Ru=CH]pyrimidin-2-yl-4-tosyl-
piperidine (5e): By using the same method as for the synthesis of
5c, compound 5e was obtained as a green solid (75 mg, 74% yield).
1H NMR (300 MHz, CDCl3): δ = 15.91 (s, 1 H, Ru=CHAr), 7.73
(s, 1 H, aromatic H), 7.58 (d, J = 8.4 Hz, 2 H, Tosyl Aromatic H),
7.31 (d, J = 8.4 Hz, 2 H, Tosyl Aromatic H), 7.03 (s, 4 H, mesityl
aromatic H), 5.34–5.26 [m, 1 H, (CH3)2CHOAr], 4.16 [s, 4 H,
N(CH2)2N], 3.92–3.86 [s, 4 H, piperazinyl TsN(CH2)2], 2.94–2.90
[s, 4 H, piperazinyl ArN(CH2)2], 2.43 (s, 12 H, mesityl o-CH3), 2.40
(s, 3 H, CH3PhSO2N), 2.35 (s, 6 H, mesityl p-CH3), 1.21 [d, J =
6.3 Hz, 6 H, (CH3)2CHOAr] ppm. 13C NMR (75 MHz, CDCl3): δ
= 296.98, 211.01, 164.99, 160.33, 159.65, 149.42, 144.17, 138.95,
131.84, 129.99, 129.42, 127.87, 127.72, 76.10, 51.75, 45.96, 44.22,
21.99, 21.62, 21.49 ppm. C40H50Cl2N6O3RuS·H2O: calcd. C 54.29,
H 5.92, N 9.50; found C 54.18, H 5.97, N 9.08.
5-Methyl-1-tosyl-1,2,3,6-tetrahydropyridine (11c):[18] White solid.
1H NMR (300 MHz, CDCl3): δ = 7.70 (d, J = 8.1 Hz, 2 H), 7.34
(d, J = 8.1 Hz, 2 H), 5.43 (t, J = 1.5 Hz, 2 H), 3.42 (s, 2 H), 3.12
(m, 2 H), 2.42 (s, 3 H), 2.18–2.17 (m, 2 H), 1.65 (s, 3 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 143.76, 133.46, 130.18, 129.93,
127.99, 119.55, 48.60, 42.91, 25.56, 21.96, 21.05 ppm. MS (ESI):
m/z = 252 [M + H]+.
3,4-Dimethyl-1-tosyl-2,5-dihydro-1H-pyrrole (11e):[19] White solid.
1H NMR (300 MHz, CDCl3): δ = 7.73 (d, J = 8.4 Hz, 2 H), 7.33
(d, J = 8.4 Hz, 2 H), 3.97 (s, 4 H), 2.43 (s, 3 H), 1.54 (s, 6 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 143.34, 134.20, 129.78, 127.55,
126.26, 59.03, 21.85, 11.47 ppm. MS (ESI): m/z = 252 [M + H]+.
2-Methyl-2-phenyl-3-vinyl-2,5-dihydrofuran (11h):[18] Colorless oil.
1H NMR (300 MHz, CDCl3): δ = 7.46–7.44 (m, 2 H), 7.36–7.34
(m, 2 H), 7.31–7.28 (m, 1 H), 6.25 (dd, J = 17.7, 0.9 Hz, 1 H), 6.00
(s, 1 H), 5.12–5.02 (m, 2 H), 4.79–4.77 (m, 2 H), 1.81 (s, 3 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 144.87, 144.60, 129.00, 128.43,
127.62, 125.26, 124.48, 117.23, 90.02, 73.42, 24.80 ppm. MS (ESI):
m/z = 187 [M + H]+.
1,4-Bis[4-OiPr-5-(4,5-dihydroIMES)Cl2Ru=CH]pyrimidin-2-yl-
piperazine (5f): By using the same method as for the synthesis of
5c, compound 5f was obtained as a green solid (57 mg, 72% yield).
1H NMR (300 MHz, CDCl3): δ = 15.88 (s, 2 H, Ru=CHAr), 7.81
(s, 2 H, aromatic H), 7.05 (s, 8 H, mesityl aromatic H), 5.37 [m, 2
H, (CH3)2CHOAr], 4.17 [s, 8 H, N(CH2)2N], 3.79 (s, 8 H, piperazi-
nyl CH2) 2.46 (s, 24 H, mesityl o-CH3), 2.38 (s, 12 H, mesityl p-
CH3), 1.26 [d, J = 6.3 Hz, 12 H, (CH3)2CHOAr] ppm. 13C NMR
(75 MHz, CDCl3): δ = 297.04, 211.34, 165.04, 160.05, 149.57,
138.96, 129.49, 129.47, 76.05, 51.86, 44.45, 21.71, 21.55 ppm.
C62H78Cl4N10O2Ru2 (1339.32): calcd. C 55.60, H 5.87, N 10.46;
found C 55.41, H 5.98, N 10.32.
1,1Ј-Diphenyl-2,2Ј,5,5Ј-tetrahydro-1H,1ЈH-3,3Ј-bipyrrole (11i):
1
White solid. H NMR (300 MHz, CDCl3): δ = 7.29 (t, J = 7.8 Hz,
4 H), 6.73 (d, J = 7.5 Hz, 2 H), 6.61 (d, J = 7.8 Hz, 4 H), 5.88 (s,
2 H), 4.33–4.25 (m, 8 H) ppm. 13C NMR (75 MHz, CDCl3): δ =
147.01, 133.51, 129.63, 122.86, 116.36, 111.56, 55.68, 54.83 ppm.
MS (ESI): m/z = 289 [M + H]. HRMS (ESI): calcd. for C20H21N2
[M + H]+ 289.1705; found 289.1702.
General Procedure for RCM and Enyne Metathesis Reaction: To a
mixture of alkene (0.1 mmol) in CH2Cl2 (50 mL, c = 0.02 m) was
added a solution of Ru-catalyst (0.1–4 mol-%) in CH2Cl2 (1 mL).
The resulting mixture was stirred at 0–80 °C for 1–24 h. The solvent
was removed under reduced pressure. The crude product was puri-
fied by flash chromatography (eluant petroleum ether/ethyl acet-
ate).
General Procedure for CM Reaction: To a mixture of alkene
(0.1 mmol) and cross-metathesis partner (0.2 mmol) in CH2Cl2
(5 mL) was added a solution of Ru-catalyst (0.5–4.0 mol-%) in
CH2Cl2 (1 mL). The resulting mixture was stirred at 25 °C for 1–
5 h. The solvent was removed under reduced pressure. The crude
product was purified by flash chromatography (eluant petroleum
ether/ethyl acetate).
1-Tosyl-2,5-dihydro-1H-pyrrole (11a):[14] White solid. 1H NMR
(300 MHz, CDCl3): δ = 7.70 (d, J = 8.4 Hz, 2 H), 7.30 (d, J =
8.4 Hz, 2 H), 5.62 (s, 2 H), 4.09 (s, 4 H), 2.40 (s, 3 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 143.58, 134.21, 129.89, 127.50,
125.56, 55.12, 21.86 ppm. MS (ESI): m/z = 224 [M + H]+.
Ethyl 7-[(tert-butyldimethylsilyl)oxy]hept-2-enoate (13a):[20] Ob-
tained as a colorless oil (E/Z = 97:3). 1H NMR (300 MHz, CDCl3):
δ = 6.95 (dt, J = 6.9, 15.6 Hz, 1 H), 5.83 (d, J = 15.6 Hz, 1 H),
4.18 (q, J = 7.2 Hz, 2 H), 3.60 (t, J = 6.0 Hz, 2 H), 2.24–2.17 (m,
2 H), 1.52–1.45 (m, 4 H), 1.27 (t, J = 7.2 Hz, 3 H), 0.88 (s, 9 H),
0.03 (s, 6 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 166.87, 149.34,
121.61, 63.10, 60.50, 32.62, 32.37, 26.39, 24.80, 18.80, 14.75,
–4.80 ppm. MS (ESI): m/z = 287 [M + H]+.
1-Tosyl-2,3,6,7-tetrahydro-1H-azepine (11d):[15] White solid. 1H
NMR (300 MHz, CDCl3): δ = 7.67 (d, J = 8.1 Hz, 2 H), 7.31 (d,
J = 8.1 Hz, 2 H), 5.76–4.72 (m, 2 H), 3.27 (t, 4 H), 2.42 (s, 3 H),
2.31–2.30 (m, 4 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 143.21,
136.24, 130.32, 129.79, 127.14, 48.53, 30.18, 21.83 ppm. MS (ESI):
m/z = 252 [M + H]+.
7-[(tert-Butyldimethylsilyl)oxy]hept-2-enenitrile (13b):[21] Obtained
1
as a colorless oil (E/Z = 24:77). H NMR (300 MHz, CDCl3): δ =
Dimethyl Cyclopent-3-ene-1,1-dicarboxylate (11f):[16] Colorless oil.
1H NMR (300 MHz, CDCl3): δ = 5.61 (s, 2 H), 3.74 (s, 6 H), 3.02
(s, 4 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 172.33, 128.02,
59.08, 53.28, 41.34 ppm. MS (ESI): m/z = 185 [M + H]+.
6.72 (dt, J = 6.9, 16.2 Hz, 1 H, E isomer), 6.48 (dt, J = 7.5, 11.1 Hz,
1 H, Z isomer), 5.32 (d, J = 11.1 Hz, 1 H), 3.64–3.58 (m, 2 H),
2.47–2.41 (m, 2 H, Z isomer), 2.27–2.21 (m, 2 H, E isomer), 1.56–
1.50 (m, 4 H), 0.88 (s, 9 H), 0.04 (s, 6 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 155.22, 116.27, 99.89, 62.87, 32.47, 32.04, 26.37, 25.08,
18.79, –4.82 ppm. MS (ESI): m/z = 240 [M + H]+.
1
2,2-Diphenyl-3-vinyl-2,5-dihydrofuran (11g):[17] Colorless oil. H
NMR (300 MHz, CDCl3): δ = 7.39–7.29 (m, 10 H), 6.30–6.20 (m,
2 H), 5.36 (d, J = 17.4 Hz, 1 H), 5.14 (d, J = 10.8 Hz, 1 H), 4.81–
4.80 (m, 2 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 143.83,
143.50, 129.97, 128.11, 127.67, 125.14, 117.81, 94.83, 73.55 ppm.
MS (ESI): m/z = 249 [M + H]+.
7-[(tert-Butyldimethylsilyl)oxy]hept-2-en-1-yl Acetate (13c):[22] Ob-
tained as a colorless oil (E/Z = 100:0). 1H NMR (300 MHz,
CDCl3): δ = 5.81–5.71 (m, 1 H), 5.60–5.51 (m, 1 H), 4.50 (d, J =
6.3 Hz, 2 H), 3.59 (t, J = 6.3 Hz, 2 H), 2.12–2.05 (m, 2 H), 2.05 (s,
Eur. J. Org. Chem. 2012, 6777–6784
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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6783

G.-L. Wu, S.-L. Cao, J. Chen, Z. Chen
FULL PAPER
3 H), 1.53–1.39 (m, 4 H), 0.88 (s, 9 H), 0.03 (s, 6 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 172.33, 136.64, 124.10, 65.65, 63.33,
32.69, 32.42, 26.40, 25.55, 21.50, 18.82, –4.78 ppm. MS (ESI): m/z
= 287 [M + H]+.
42, 1900–1923; d) G. Lesma, A. Colombo, A. Sacchetti, A.
Silvani, J. Org. Chem. 2009, 74, 590–596; e) A. W. van Zijl, A. J.
Minnaard, B. L. Feringa, J. Org. Chem. 2008, 73, 5651–5653;
f) S. Hanessian, H. Sailes, A. Munro, E. Therrien, J. Org.
Chem. 2003, 68, 7219–7233.
Methyl 2-{[(Benzyloxy)carbonyl]amino}-8-[(tert-butyldimethylsilyl)-
oxy]oct-3-enoate (13d): Obtained as a colorless oil (E/Z = 100:0).
1H NMR (300 MHz, CDCl3): δ = 7.35–7.30 (m, 5 H), 5.2–5.72 (m,
1 H), 5.50–5.38 (m, 2 H), 5.12 (s, 2 H), 4.85 (t, J = 6.3 Hz, 1 H),
3.75 (s, 3 H), 3.59 (t, J = 6.0 Hz, 2 H), 2.10–2.03 (m, 2 H), 1.52–
1.38 (m, 4 H), 0.89 (s, 9 H), 0.04 (s, 6 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 171.67, 155.60, 136.38, 135.39, 135.22, 128.73, 128.39,
124.17, 67.38, 63.28, 56.03, 52.99, 32.64, 32.32, 26.40, 25.45, 18.81,
–4.78 ppm. MS (ESI): m/z = 436.4 [M + H]+, 458.4 [M + Na]+.
HRMS (FT-ICR): calcd. for C23H38NO5Si 436.2519 [M + H]+;
found 436.2512.
tert-Butyldimethyl[(6-phenylhex-5-en-1-yl)oxy]silane (13e):[23] Ob-
tained as a colorless oil (E/Z = 100:0). 1H NMR (300 MHz,
CDCl3): δ = 7.35–7.16 (m, 5 H), 6.41 (d, J = 16.2 Hz, 1 H), 6.27–
6.19 (m, 1 H), 3.63 (t, J = 6.3 Hz, 2 H), 2.30–2.19 (m, 2 H), 1.57–
1.51 (m, 4 H), 0.89 (s, 9 H), 0.05 (s, 6 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 131.15, 130.25, 130.11, 128.69, 127.02, 126.14, 63.45,
33.25, 32.81, 26.43, 26.07, 18.86, –4.73 ppm. MS (ESI): m/z = 290
[M]+.
3-Phenylallyl Acetate (13f):[24] Obtained as a colorless oil (E/Z =
100). 1H NMR (300 MHz, CDCl3): δ = 7.40–7.25 (m, 5 H), 6.68
(d, J = 15.9 Hz, 1 H), 6.28 (dt, J = 15.9, 6.3 Hz, 1 H), 4.74 (d, J =
6.3 Hz, 2 H), 2.10 (s, 3 H) ppm. 13C NMR (75 MHz, CDCl3): δ =
170.98, 136.37, 134.41, 128.82, 128.29, 126.82, 123.36, 65.44,
21.47 ppm. MS (ESI): m/z = 177 [M + H]+.
ROMP of Norbornene (14):[11] To a solution of norbornene
(47.1 mg, 0.5 mmol) in CDCl3 (1 mL) in a flame-dried NMR spec-
trometry tube, was added Ru catalyst (0.0025 mmol) under an ar-
gon atmosphere. After 30 min, the reaction mixture was analyzed
by 1H NMR spectroscopy. 1H NMR (300 MHz, CDCl3): δ = 5.34–
5.16 (m, 2 H), 2.80–2.70 (m, 1 H), 2.50–2.40 (m, 1 H), 1.80–1.76
(m, 3 H), 1.40–1.30 (m, 2 H), 1.10–1.00 (m, 1 H) ppm.
[3] a) M. S. Sanford, M. Ulman, R. H. Grubbs, J. Am. Chem. Soc.
2001, 123, 749–750; b) M. S. Sanford, J. A. Love, R. H.
Grubbs, J. Am. Chem. Soc. 2001, 123, 6543–6554.
[4] a) S. B. Garber, J. S. Kingsbury, B. L. Gray, A. Hoveyda, J. Am.
Chem. Soc. 2000, 122, 8168–8179; b) R. Bujok, M. Bieniek, M.
Masnyk, A. Michrowska, A. Sarosiek, H. Stepowska, D. Arlt,
K. Grela, J. Org. Chem. 2004, 69, 6894–6896.
[5] a) V. Thiel, M. Hendann, K. Wannowius, H. Plenio, J. Am.
Chem. Soc. 2012, 134, 1104–1114; b) M. Bieniek, C. Samojzow-
icz, V. Sashuk, R. Bujok, P. Sledz, N. Lugan, G. Lavigne, D.
Arlt, K. Grela, Organometallics 2011, 30, 4144–4158.
[6] a) H. Wakamatsu, S. Blechert, Angew. Chem. 2002, 114, 2509–
2511; Angew. Chem. Int. Ed. 2002, 41, 2403–2405; b) H. Waka-
matsu, S. Blechert, Angew. Chem. 2002, 114, 832–834; Angew.
Chem. Int. Ed. 2002, 41, 794–796.
[7] a) K. Grela, S. Harutyunyan, A. Michrowska, Angew. Chem.
2002, 114, 4210–4212; Angew. Chem. Int. Ed. 2002, 41, 4038–
4040; b) A. Michrowska, R. Bujok, S. Harutyunyan, V. Sashuk,
G. Dolgonos, K. Grela, J. Am. Chem. Soc. 2004, 126, 9318–
9325.
[8] a) J. A. Love, J. P. Morgan, T. M. Trnka, R. H. Grubbs, Angew.
Chem. 2002, 114, 4207–4209; Angew. Chem. Int. Ed. 2002, 41,
4035–4037; b) A. Szadkowska, X. Gstrein, D. Burtscher, K.
Jarzembska, K. Wozniak, C. Slugovc, K. Grela, Organometal-
lics 2010, 29, 117–124.
[9] M. M. Barbasiewicz, M. Bieniek, A. Michrowska, A. Szadkow-
ska, A. Makal, K. WozЈniak, K. Grela, Adv. Synth. Catal.
2007, 349, 193–203.
[10] During the reaction of 8a and 8b with complex 1, green spots
can be observed by TLC monitoring. However, all attempts to
isolate these unstable products were unsuccessful.
[11]
G. C. Vougioukalakis, R. H. Grubbs, J. Am. Chem. Soc. 2008,
130, 2234–2245.
[12]
The gel permeation (GP) chromatograms and the number
average molecular weight (Mn), molecular weight (Mw) and
polydispersity index (PDI) data for the polymer products,
which were obtained for catalysts 5c, 5d, 5e, and 5f are pro-
vided in the Supporting Information.
Considering the Grela group’s result, we thought that the elec-
tro-deficient effect might play a major role in enhancing ac-
tivity. However, the steric effect might also affect the catalyst’s
activity, as one referee of this article suggested.
Supporting Information (see footnote on the first page of this arti-
cle): General reaction conditions and NMR spectra of all com-
pounds are provided.
[13]
Acknowledgments
[14] Y. Terada, M. Mitsuhiro, A. Nishida, Angew. Chem. 2004, 116,
4155–4159; Angew. Chem. Int. Ed. 2004, 43, 4063–4067.
[15] K. Grela, M. Kim, Eur. J. Org. Chem. 2003, 963–966.
[16] Q. Yao, Y. Zhang, J. Am. Chem. Soc. 2004, 126, 74–75.
[17] H. Clavier, S. P. Nolan, Chem. Eur. J. 2007, 13, 8029–8036.
[18] J. Verendel, T. Zhou, J. Q. Li, A. Paptchikhine, O. Lebedev,
P. G. Andersson, J. Am. Chem. Soc. 2010, 132, 8880–8881.
[19] A. Fürstner, O. Guth, A. Düffels, G. Seidel, M. Liebl, B.
Gabor, R. Mynott, Chem. Eur. J. 2001, 7, 4811–4820.
[20] M. E. Jung, J. A. Berliner, L. Koroniak, B. G. Gugiu, A. D.
Watson, Org. Lett. 2008, 10, 4207–4209.
Support of this work by the grant from National Sciences Founda-
tion of China (20972099), and HRMS and elemental analyses by
Prof. Yu-Wu Zhong’s group are gratefully acknowledged.
[1] a) T. M. Trnka, R. H. Grubbs, Acc. Chem. Res. 2001, 34, 18–
29; b) K. C. Nicolaou, P. G. Bulger, D. Sarlah, Angew. Chem.
2005, 117, 4564–4601; Angew. Chem. Int. Ed. 2005, 44, 4490–
4527; c) A. M. Lozano-Vila, S. Monsaert, A. Bajek, F. Ver-
poort, Chem. Rev. 2010, 110, 4865–4909; d) T. J. Donohoe, A. J.
Orr, M. Bingham, Angew. Chem. 2006, 118, 2730–2736; Angew.
[21] W. E. Crowe, D. R. Goldberg, J. Am. Chem. Soc. 1995, 117,
5162–5163.
Chem. Int. Ed. 2006, 45, 2664–2670; e) A. Fürstner, Angew. [22] A. Michrowska, R. Bujok, S. Harutyunyan, V. Sashuk, G. Dol-
Chem. Int. Ed. 2000, 39, 3013; f) R. R. Schrock, A. H. Hov- gonos, K. Grela, J. Am. Chem. Soc. 2004, 126, 9318–9325.
eyda, Angew. Chem. 2003, 115, 4740–4782; Angew. Chem. Int. [23] G. A. Molander, T. Fumagalli, J. Org. Chem. 2006, 71, 5743–
Ed. 2003, 42, 4592–4633.
5747.
[2] a) G. C. Vougioukalakis, R. H. Grubbs, Chem. Rev. 2010, 110,
1746–1787; b) C. Samojłowicz, M. Bieniek, K. Grela, Chem.
Rev. 2009, 109, 3708–3742; c) S. G. Connon, S. Blechert, An-
gew. Chem. 2003, 115, 1944–1968; Angew. Chem. Int. Ed. 2003,
[24] L. T. Pilarski, P. G. Janson, K. J. Szabo, J. Org. Chem. 2011,
76, 1503–1506.
Received: July 25, 2012
Published Online: October 23, 2012
6784
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Eur. J. Org. Chem. 2012, 6777–6784