Synthesis and Reactivity of Homogeneous and Heterogeneous Ruthenium-Based Metathesis Catalysts Containing Electron-Withdrawing Ligands

Article abstract of DOI:10.1002/chem.200305031

The synthesis and heterogenization of new Grubbs-Hoveyda type metathesis catalysts by chlorine exchange is described. Substitution of one or two chlorine ligands with trifluoroacetate and trifluoromethanesulfonate was accomplished by reaction of [RuCl₂(=CH-o-iPr-O-C₆H ₄)(IMesH₂)] (IMesH₂ = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) with the silver salts CF₃COOAg and CF₃SO₃Ag, respectively. The resulting compounds, [Ru(CF₃SO₃) ₂(=CH-o-iPr-O-C₆H₄)(IMesH₂)] (1), [RuCl(CF₃SO₃)(=CH-o-iPr-O-C₆H ₄)(IMesH₂)] (2), and [Ru(CF₃CO ₂)₂(=CH-o-iPr-O-C₆H₄)(IMesH ₂)] (3) were found to be highly active catalysts for ring-closing metathesis (RCM) at elevated temperature (45°C), exceeding known ruthenium-based catalysts in catalytic activity. Turn-over numbers (TONs) up to 1800 were achieved in RCM. Excellent yields were also achieved in enyne metathesis and ring-opening cross metathesis using norborn-5-ene and 7-oxanorborn-5-ene-derivatives. Even more important, 3 was found to be highly active in RCM at room temperature (20°C), allowing TONs up to 1400. Heterogeneous catalysts were synthesized by immobilizing [RuCl₂(= CH-o-iPr-O-C₆H₄)(IMesH₂)] on a perfluoroglutaric acid derivatized polystyrene-divinylbenzene (PS-DVB) support (silver form). The resulting supported catalyst [RuCl(polymer-CH ₂-O-CO-CF₂-CF₂-CF ₂-COO)(=CH-o-iPr-O-C₆H₄)(IMesH₂)] (5) showed significantly reduced activities in RCM (TONs = 380) compared with the heterogeneous analogue of 3. The immobilized catalyst, [Ru(polymer-CH ₂-O-CO-CF₂-CF₂-CF₂-COO)(CF ₃CO₂)(=CH-o-iPr-O-C₆H₄)(IMesH ₂)] (4) was obtained by substitution of both Cl ligands of the parent Grubbs-Hoveyda catalyst by addition of CF₃COOAg to 5. Compound 4 can be prepared in high loadings (160 mg catalyst g^-1 PS-DVB) and possesses excellent activity in RCM with TONs up to 1100 in stirred-batch RCM experiments. Leaching of ruthenium into the reaction mixture was unprecedentedly low, resulting in a ruthenium content <70 ppb (ng g ^-1) in the final RCM-derived products.

Full text of DOI:10.1002/chem.200305031

FULL PAPER
Synthesis and Reactivity of Homogeneous and Heterogeneous Ruthenium-
Based Metathesis Catalysts Containing Electron-Withdrawing Ligands
[a]
[c]
Jens O.Krause, Oskar Nuyken,*[a] Klaus Wurst,[b] and Michael R.Buchmeiser*
Abstract: The synthesis and heteroge-
nization of new Grubbs Hoveyda type
metathesis catalysts by chlorine ex-
change is described. Substitution of
one or two chlorine ligands with tri-
fluoroacetate and trifluoromethanesul-
fonate was accomplished by reaction of
[RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)]
were achieved in RCM. Excellent
yields were also achieved in enyne
metathesis and ring-opening cross
metathesis using norborn-5-ene and 7-
CO-CF2-CF2-CF2-COO)(=CH-o-iPr-O-
C6H4)(IMesH2)] (5) showed significant-
ly reduced activities in RCM (TONs =
380) compared with the heterogeneous
analogue of 3. The immobilized cata-
lyst, [Ru(polymer-CH2-O-CO-CF2-CF2-
CF2-COO)(CF3CO2)(=CH-o-iPr-O-
C6H4)(IMesH2)] (4) was obtained by
substitution of both Cl ligands of the
parent Grubbs Hoveyda catalyst by
addition of CF3COOAg to 5. Com-
pound 4 can be prepared in high load-
ings (160 mg catalystgÀ1 PS-DVB) and
possesses excellent activity in RCM
with TONs up to 1100 in stirred-batch
RCM experiments. Leaching of ruthe-
nium into the reaction mixture was un-
precedentedly low, resulting in a ruthe-
nium content <70 ppb (nggÀ1) in the
final RCM-derived products.
oxanorborn-5-ene-derivatives.
Even
more important, 3 was found to be
highly active in RCM at room temper-
ature (208C), allowing TONs up to
1400. Heterogeneous catalysts were
synthesized by immobilizing [RuCl2(=
CH-o-iPr-O-C6H4)(IMesH2)] on a per-
fluoroglutaric acid derivatized polystyr-
ene-divinylbenzene (PS-DVB) support
(silver form). The resulting supported
(IMesH2
=
1,3-bis(2,4,6-trimethyl-
phenyl)-4,5-dihydroimidazol-2-ylidene)
with the silver salts CF3COOAg and
CF3SO3Ag, respectively. The resulting
compounds, [Ru(CF3SO3)2(=CH-o-iPr-
O-C6H4)(IMesH2)] (1), [RuCl(CF3-
SO3)(=CH-o-iPr-O-C6H4)(IMesH2)] (2),
and [Ru(CF3CO2)2(=CH-o-iPr-O-C6H4)-
(IMesH2)] (3) were found to be highly
active catalysts for ring-closing meta-
thesis (RCM) at elevated temperature
(458C), exceeding known ruthenium-
based catalysts in catalytic activity.
Turn-over numbers (TONs) up to 1800
catalyst
[RuCl(polymer-CH2-O-
Keywords: heterogeneous
catalysis ¥ homogeneous catalysis ¥
metathesis ¥ ruthenium ¥ supported
catalysts
Introduction
[a] Dipl.-Chem. J. O. Krause, Prof. Dr.-Ing. O. Nuyken
Lehrstuhl f¸r Makromolekulare Stoffe
Technische Universit‰t M¸nchen
With well-defined initiators in hand,[1] olefin metathesis has
become a powerful tool in organic synthesis.[2] While high
activities have long been the domain of molybdenum-based
Schrock initiators, the use of NHCs (NHC: N-heterocyclic
Lichtenbergstrasse 4, 85747 Garching (Germany)
Fax : (+49)89-289-13562
E-mail: jens.krause@ch.tum.de
oskar.nuyken@ch.tum.de
carbene) have added another active class of catalysts to the
arsenal of synthetic organic chemistry.[3
Both NHC li-
12]
[b] Dr. K. Wurst
Institut f¸r Allgemeine, Anorganische und Theoretische Chemie
Universit‰t Innsbruck, Innrain 52a
6020 Innsbruck (Austria)
Fax : (+43)512-507-2934
E-mail: klaus.wurst@uibk.ac.at
gands and carbene groups in ruthenium-derived catalysts
have been optimized through the years. Nevertheless, only
little attention has been dedicated to the replacement of the
chlorine ligands. This is presumably a consequence of the re-
sults reported by Grubbs et al. who varied the halogens in
the [RuCl2(=CH=CHCPh2)(PCy3)2] system.[13] Replacement
of both chlorine ligands by bromine, iodine, or trifluoroace-
tate led to less active or less stable catalysts. In contrast,
changing the halide from Cl to Br or I in [RuCl2(CHPh)-
(IMesH2)] results in increased initiation rates in ROMP,
[c] Prof. Dr. M. R. Buchmeiser
Institut f¸r Analytische Chemie und Radiochemie
Universit‰t Innsbruck, Innrain 52 a, 6020 Innsbruck (Austria)
Fax : (+43)512-507-2677
E-mail: michael.r.buchmeiser@uibk.ac.at
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
777
Chem. Eur. J. 2004, 10, 777 784
DOI: 10.1002/chem.200305031
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

FULL PAPER
nevertheless, propagation rates were found to be reduced at
least in the ROMP of cyclooctene.[14] The results clearly
show that replacement of the halide in this type of complex
with other groups has a dramatic effect on reactivity, though
it is hard to predict whether it will be an increase or de-
crease. This is further underlined by the finding that an
almost dramatic change in enantioselectivity in RCM occurs
when the ligand sphere in [RuCl2(CHPh)(NHC)]-type com-
plexes bearing chiral NHCs is changed from Cl to Br and
I.[15] Recently, Buchowicz et al. showed that replacement of
both chlorines in [RuCl2(=CHPh)(PCy3)2] with strongly
electron-withdrawing fluorocarboxylates results in stable
systems and gives access to heterogenization.[16,17] Quite re-
cently, we reported on the synthesis of both homogeneous
and heterogeneous catalysts by replacement of one chlorine
ligand in an NHC-based Grubbs Herrmann-catalyst.[18]
Though accessible and highly active, any phosphane-contain-
ing catalyst suffers from a lack of stability owing to forma-
tion of AgCl and AgCl(PCy3) during synthesis. Our aim was
to apply the concept of chlorine replacement by ligands con-
taining electron-withdrawing groups (e.g. fluorinated car-
boxylates and sulfonates) to a phosphane-free catalyst. In
this contribution, we report on the synthesis of a new gener-
ation of metathesis catalysts accessible by replacement of
one or both chlorines in the phosphane-free Grubbs Hovey-
da catalyst by trifluoroacetate and trifluoromethanesulfo-
nate groups. Furthermore, heterogenization on macroreticu-
lar poly(styrene-co-divinylbenzene) resins was achieved. In
order to benchmark the new systems, they were all subject
to various metathesis-type reactions. The new catalysts were
found to be equally or more active in RCM than existing
ruthenium-based metathesis catalysts. Excellent reactivity
was also observed in enyne metathesis and ring-opening
cross metathesis. In the following, the synthesis of the new
catalysts, their structure and catalytic activity shall be out-
lined in detail.
Scheme 1. Synthesis of catalysts 1, 2, and 3.
complex [RuCl2(=CH-iPr-O-C6H4)(IMesH2)] are reduced to
231.82(7) pm for Ru(1)ÀCl(1) in 2. As a consequence of this
stronger binding, substitution of the second chlorine is less
favored. In addition, replacement of the second Cl ligand is
hampered because of the higher pKa of the conjugated acid
(CF3SO3H) of the ligand to be introduced. These effects to-
gether result in the longer reaction times observed. Similar
to 3 (see below), the angle O(1)-Ru(1)-C(2) is close to 1808
(178.17(8)8). Compared with the parent complex [RuCl2-
(=CH-iPr-O-C6H4)(IMesH2)][19] and 3, the angle between
the chlorine ligand and the trifluoromethanesulfonate group
is widened to 160.87(6)8.
Synthesis and structure of Ru complex 3: For the synthesis
of catalyst 3 (Figure 2), a similar procedure was used. Pre-
sumably because of the softer character of the CF3COO
ligand (according to the HSAB principle) and the larger
pKa of the corresponding conjugated acid (CF3COOH),
both chlorines can be substituted in a clean reaction. All at-
tempts to isolate the monotrifluroacetate-substituted cata-
lyst failed; under all chosen conditions between À1968C and
Results and Discussion
Synthesis and structure of Ru complexes 1 and 2: Catalysts
1 and 2 were obtained by adding two or one equivalent of
CF3SO3Ag,
respectively,
to
[RuCl2(=CH-iPr-O-
C6H4)(IMesH2)] (Scheme 1).
Whereas the substitution of the first ligand proceeds
smoothly, replacement of the second requires prolonged re-
action times. Both compounds were obtained in virtually
1
quantitative yields, as demonstrated by in situ H N MR ex-
periments, and can be used without any purification. In case
AgCl needs to be removed, the protocol described in the
Experimental Section offers access to a silver-free catalyst,
however, reduced yields (52 56%) have to be accepted. In
order to retrieve structural information, 2 was subjected to
X-ray crystallographic analysis (Figure 1). Compound 2 crys-
tallizes in the monoclinic space group P21/c, a = 1234.41(3)
pm, b = 1604.50(3) pm, c = 1704.55(3) pm, b = 91.077(2)8,
Z = 4. Selected X-ray data are summarized in Table 1,
bond lengths and angles are given in Table 2. The RuÀCl
distances of 232.79(12) and 233.93(12) pm,[19] in the parent
Figure 1. X-ray structure of 2.
778
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Chem. Eur. J. 2004, 10, 777 784

Ruthenium-Based Metathesis Catalysts
777 784
Table 1. Selected X-ray data for compounds 2 and 3.
2
3
formula
FW
C32H38ClF3N2O4RuS
740.22
C35H38F6N2O5Ru
781.74
cryst. system
space group
a [pm]
b [pm]
c [pm]
a [8]
monoclinic
P21/c (no. 14)
1234.41(3)
1604.50(3)
1704.55(3)
90
monoclinic
P21/n (no. 14)
1189.39(3)
1664.62(3)
1862.86(3)
90
b [8]
91.077(2)
90
3.37545(12)
4
90.086(2)
90
3.68824(13)
4
g [8]
V [nm3]
Z
T [K]
233(2)
1.457
0.660
233(2)
1.408
0.496
1calcd [MgmÀ3
]
m [mmÀ1
]
color, habit
yellow plate
5211
reddish prism
6169
refls with I>2s(I)
GOF on F2
R indices I > 2s(I)
R1
1.052
1.054
0.0315
0.0789
0.0300
0.0749
Figure 2. X-ray structure of 3.
wR2
ty and stability of 3 can be explained by the trans-effect of
the NHC ligand on the iPr-O group (O(1)-Ru(1)-C(2)
178.93(8)8, parent complex 176.22(14)8).
Table 2. Selected bond lengths [pm] and angles [8] for 2.
Ru(1)ÀC(1)
182.0(3)
198.4(2)
Ru(1)ÀC(2)
The fact that only monomeric compounds are obtained is
in strong contrast to the findings of Buchowitz et al. for the
[RuCl2(=CHPh)(PCy3)2]-derived catalysts.[16,17] The clear ad-
vantage of such monomeric catalysts is that no dissociation
of any dimeric catalyst precursor is necessary, which enhan-
ces both the reaction rates and stability of the entire catalyt-
ic setup. In contrast to the work by Hoveyda,[19] in which the
weaker electron-donating character of the oxygen in the iso-
propoxide group should result in an upfield shift of the ben-
zylidene proton, we could not observe such correlation in
catalysts 1 3.
Ru(1)ÀO(2)
209.86(19)
224.99(17)
231.82(7)
102.34(11)
98.87(10)
93.50(9)
79.31(10)
178.17(8)
85.43(7)
97.21(9)
93.12(7)
160.87(6)
87.44(5)
Ru(1)ÀO(1)
Ru(1)ÀCl(1)
C(1)-Ru(1)-C(2)
C(1)-Ru(1)-O(2)
C(2)-Ru(1)-O(2)
C(1)-Ru(1)-O(1)
C(2)-Ru(1)-O(1)
O(2)-Ru(1)-O(1)
C(1)-Ru(1)-Cl(1)
C(2)-Ru(1)-Cl(1)
O(2)-Ru(1)-Cl(1)
O(1)-Ru(1)-Cl(1)
Synthesis of heterogeneous catalysts 4 and 5: For purposes
of heterogenization, hydroxymethyl-polystyrene (PS-DVB-
CH2-OH, 1.7 mmol CH2-OHgÀ1, crosslinked with 1% DVB)
was treated with perfluoroglutaric anhydride following a
procedure published by Nieczypor et al.[20] Deprotonation
and formation of the silver salt were accomplished by reac-
tion with aqueous sodium hydroxide followed by treatment
room temperature and with varying stoichiometry, only a
1:1:8 mixture of reactants, bis-, and monoadduct (identified
by means of H NMR spectroscopy) could be isolated. We
1
therefore were only able to isolate the bis(trifluoroacetate)-
substituted catalyst 3 in a pure form. As for 1 and 2, 3 is ob-
tained in virtually quantitative yield as again demonstrated
1
by in situ H NMR experiments, and can be used without
Table 3. Selected bond lengths [pm] and angles [8] for 3.
any purification. Removal of AgCl to obtain analytically
pure catalyst results in reduced yields (71%).
Ru(1)ÀC(1)
182.6(2)
197.9(2)
Ru(1)ÀC(2)
Ru(1)ÀO(4)
202.58(15)
203.65(16)
224.58(15)
100.83(9)
97.91(8)
92.26(7)
103.11(8)
92.31(7)
157.23(6)
79.20(8)
178.93(8)
86.67(7)
Compound 3 (Figure 2) crystallizes in the space group
P21/n, a = 1189.39(3), b = 1664.62(3), c = 1862.86(3) pm,
b = 90.086(2)8, Z = 4. Selected X-ray data are summarized
in Table 1, bond lengths and angles are given in Table 3. The
angle formed by O(2)-Ru(1)-O(4) is 157.23(6)8, which is
similar to the angle of 156.47(5)8 found for Cl(1)-Ru-Cl(2)
Ru(1)ÀO(2)
Ru(1)ÀO(1)
C(1)-Ru(1)-C(2)
C(1)-Ru(1)-O(4)
C(2)-Ru(1)-O(4)
C(1)-Ru(1)-O(2)
C(2)-Ru(1)-O(2)
O(4)-Ru(1)-O(2)
C(1)-Ru(1)-O(1)
C(2)-Ru(1)-O(1)
O(4)-Ru(1)-O(1)
O(2)-Ru(1)-O(1)
in
the
parent
complex
[RuCl2(=CH-o-iPr-O-
C6H4)(IMesH2)].[19] The Ru(1)ÀO(1) distance is basically un-
changed (2.261(3) ä in the parent complex versus
2.2458(15) ä in 3), which is in accordance with the high sta-
bility of 3. As for the parent complex, both the high reactivi-
88.73(7)
779
Chem. Eur. J. 2004, 10, 777 784
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O. Nuyken, M. R. Buchmeiser et al.
FULL PAPER
with AgNO3. [RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)] was dis-
solved in THF and added to the silver salt. By this approach,
[RuCl(polymer-CH2-O-CO-CF2-CF2-CF2-COO)(=CH-o-iPr-
O-C6H4)(IMesH2)] (5) was obtained. In order to synthesize
an almost identical analogue to 3, the second Cl ligand was
reacted with CF3COOAg yielding [Ru(polymer-CH2-O-CO-
CF2-CF2-CF2-COO)(CF3CO2)(=CH-o-iPr-O-C6H4)(IMesH2)]
(4) as a lilac powder (Scheme 2).
5-NO2-C6H3)(IMesH2)],[21] these data still exceed or at least
rival the activity of [RuCl2(CH-Ph)(IMesH2)(PCy3)],
[RuCl2(=CH-(1-(2-iPrO-naphth-1-yl)-2-iPrO-naphth-3-yl)-
(IMesH2)(PCy3)],
and
[Mo(N-2,6-iPr2-C6H3)(CHCMe2-
24]
Ph)(OCMe(CF3)2)2].[22
Homogeneous enyne and ring-opening cross metathesis ex-
periments: In addition to RCM experiments, enyne meta-
thesis reactions were carried out. Diethyl dipropargylmalo-
nate (DEDPM) was treated with trimethylallylsilane and tri-
phenylallylsilane. The corresponding products were obtained
in high yields (95%). Conditions identical to those reported
in the literature[25] were chosen in order to allow for compar-
ison of the reported yields. As can be deduced from Table 5
(entries 43 and 44), 3 again showed enhanced activity. Final-
ly, ring-opening cross metathesis reactions carried out with
both norborn-5-ene and 7-oxanorborn-5-ene derivatives
were investigated (Table 5, entries 45 45). Excellent yields
(95%) were obtained, again exceeding those reported in the
literature.[26]
A catalyst-loading of 160 mggÀ1 (16%) was determined
for 4, indicating that more than 80% of the polymer-bound
silver perfluoroglutarate groups were accessible for reaction
with [RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)]. This corre-
sponds to a catalyst amount five times higher than reported
for other heterogeneous systems.[20]
Homogeneous RCM experiments: In order to benchmark
the new systems, we tested their catalytic activity in RCM
using a set of six different compounds. Diethyl diallylmalo-
nate (DEDAM), 1,7-octadiene, diallyldiphenylsilane, trans-
3-methylpentenoate, N,N-diallytrifluoroacetamide, and N,N-
diallyl-tert-butylcarbamide were used. Catalysts 1 and 2 dis-
played lower activities than the parent catalyst (Table 4, en-
tries 21 32). However, RCM experiments with 3 could be
carried out with high turn-over numbers (TONs) even at
room temperature. As can be deduced from Table 4, TONs
obtained with 3 at 458C (Table 4, entries 11 18) exceed
those obtained with the Grubbs Herrmann (Table 4, entries
1 5) or the parent Grubbs Hoveyda catalysts in most cases
(Table 4, entries 6 10). Even more interesting, high TONs
(600 for DEDAM and 1380 for 1,7-octadiene, see Table 4,
entries 17 18) were obtained at 208C, underlining the high
activity of this catalytic system. Since the activity of a new
metathesis catalyst is best demonstrated by the RCM of tri-
and tetrasubstituted dienes, we carried out RCM of diethyl
allylmethallyl malonate and diethyl dimethallylmalonate
(Table 4, entries 19 20). TONs of 80 and 70, respectively
were achieved. Though slightly higher numbers (TON =
99) were obtained by other groups using [RuCl2(CH-2-iPrO-
Heterogeneous RCM experiments: For purposes of compar-
ison, DEDAM, 1,7-octadiene, diallyldiphenylsilane, trans-3-
methylpentenoate, and N,N-diallyl-tert-butylcarbamide were
used in heterogeneous RCM to benchmark the heterogene-
ous catalysts 4 and 5. For most of these monomers, both cat-
alyst 5 and 4 displayed high activities in RCM, the latter
being the superior system with TONs approaching 1100
(Table 4, entries 31 35). With 5, TONs of 380 were achieved
(Table 1, entries 36 40). With this catalytic activity, both het-
erogeneous systems presented here far exceed any other
supported metathesis catalyst. The fact that 4 exceeds 5 in
catalytic activity clearly accentuates the necessity of careful
catalyst design; in our case the substitution of both chlorine
ligands results in an almost perfect mimic of the homogene-
ous analogue 3. For both heterogeneous systems 4 and 5,
leaching of ruthenium into the various reaction mixtures
was unprecedentedly low, resulting in a ruthenium content
<70 ppb (nggÀ1) in the final
RCM-derived products.
Conclusion
With the synthesis of catalysts
1--3 we have shown that the
concept of the fixation of
strongly electron-withdrawing
ligands accelerates the catalytic
activity of Grubbs Hoveyda
type catalysts, a finding that is
in contrary to previous experi-
ments with Grubbs-type cata-
lysts. The resulting catalysts are
monomeric rather than dimeric
and exhibit surprising stability.
Thus, 3 can be stored under am-
bient conditions (i.e., room
temperature, air, and moisture)
Scheme 2. Synthesis of heterogeneous catalysts 4 and 5.
780
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Chem. Eur. J. 2004, 10, 777 784

Ruthenium-Based Metathesis Catalysts
777 784
Table 4. Summary of catalytic activities.
Compound
Catalyst
mol% compound
TON
1
2
3
4
5
6
7
8
9
DEDAM
1,7-octadiene
diallyldiphenylsilane
methyl trans-3-pentenoate
tert-butyl N,N-diallylcarbamide
DEDAM
Grubbs Herrmann[a]
0.05
0.08
0.10
0.01
0.10
0.05
0.05
0.10
0.10
0.10
0.05
0.05
0.10
0.01
0.10
0.10
0.10
0.05
0.10
0.10
0.05
0.05
0.10
0.01
0.10
0.10
0.05
0.05
0.10
0.01
0.10
0.10
0.05
0.05
0.10
0.10
0.10
0.05
0.05
0.10
0.10
0.10
1300
1000
400
600
770
1500
1700
180
60
100
1400
1800
750
300
780
1000
590
1400
80
Grubbs Herrmann[a]
Grubbs Herrmann[a]
Grubbs Herrmann[a]
Grubbs Herrmann[a]
Grubbs Hoveyda[a]
1,7-octadiene
Grubbs Hoveyda[a]
diallyldiphenylsilane
methyl trans-3-pentenoate
tert-butyl N,N-diallylcarbamide
DEDAM
Grubbs Hoveyda[a]
Grubbs Hoveyda[a]
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
Grubbs Hoveyda[a]
3[a]
3[a]
3[a]
3[a]
3[a]
3[a]
3[b]
3[b]
3[c]
3[c]
2[a]
2[a]
2[a]
2[a]
2[a]
2[a]
1[a]
1[a]
1[a]
1[a]
1[a]
1[a]
4[a]
4[a]
4[a]
4[a]
4[a]
5[a]
5[a]
5[a]
5[a]
5[a]
1,7-octadiene
diallyldiphenylsilane
methyl trans-3-pentenoate
tert-butyl N,N-diallylcarbamide
N,N-diallyltrifluoroacetamide
DEDAM
1,7-octadiene
diethyl allylmethallylmalonate
diethyl dimethallylmalonate
DEDAM
70
600
300
10
300
710
630
500
500
20
500
110
190
200
1100
100
350
70
200
400
130
190
130
1,7-octadiene
diallyldiphenylsilane
methyl trans-3-pentenoate
tert-butyl-N,N-diallylcarbamide
N,N-diallyltrifluoroacetamide
DEDAM
1,7-octadiene
diallyldiphenylsilane
methyl trans-3-pentenoate
tert-butyl-N,N-diallylcarbamide
N,N-diallyltrifluoroacetamide
DEDAM
1,7-octadiene
diallyldiphenylsilane
tert-butyl N,N-diallylcarbamide
N,N-diallyltrifluoroacetamide
DEDAM
1,7-octadiene
diallyldiphenylsilane
tert-butyl N,N-diallylcarbamide
N,N-diallyltrifluoroacetamide
[a] 2 h, 2 mL CH2Cl2, 458C. [b] 2 h, 2 mL CH2Cl2, 208C. Grubbs Hoveyda catalyst = [RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)]. [c] 2 h, 3 mL CDCl3, 458C.
Table 5. Enyne and ring-opening cross-metathesis reactions using 3.
Reactants Product
Conditions
E/Z
Yield[a]
[b]
43
44
45
1:3.5
95%(65%)[25]
[b]
[c]
1:6
1:2
95%
95%(58)[26]
[c]
46
1.1
95%
[a] Yields in parentheses are those reported by other groups using standard Ru-based metathesis catalysts. [b] CH2Cl2, 12 h, room temperature, 10 mol%
catalyst. [c] 2 mol%, 2 h, CDCl3, room temperature. Reactants for entries 45 and 46 consisted of a 1:1 mixture of the corresponding exo and endo com-
pounds.
781
Chem. Eur. J. 2004, 10, 777 784
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¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

O. Nuyken, M. R. Buchmeiser et al.
FULL PAPER
C33H38F6N2O7RuS2¥AgCl (997.176): C 39.75, H 3.84, N2.81; found C
40.07, H 4.45, N2.64.
without loss of activity. In various RCM, enyne metathesis,
and ring-opening cross metathesis experiments, 3 revealed
the highest activity ever reported both at elevated and room
temperature. Moreover, substitution of the chlorine ligands
with trifluoroacetate groups or polymer-bound analogous li-
gands offers simple access to heterogeneous analogues, as
has been demonstrated with the syntheses of 4 and 5. The
high catalytic activity can be retained during the heterogeni-
zation process, and ruthenium leaching was unprecedentedly
low, giving access to virtually Ru-free products. Investiga-
tions on the applicability of 3 and 4 in various metathesis-
based reactions including polymerizations and heterogeniza-
tion on monolithic supports[27,28] are under way.
[RuCl(CF3SO3)(=CH-o-iPr-O-C6H4)(IMesH2)] (2): Under glovebox con-
ditions [RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)] (200 mg, 0.32 mmol) was
dissolved in THF (10 mL) and a solution of CF3SO3Ag (1 equiv, 82 mg,
0.32 mmol) in THF (2 mL) was slowly added to the stirred solution. Stir-
ring was continued for 90 minutes. A color change from green to green-
yellow and the formation of a precipitate were observed. The precipitate
was filtered off and the solution evaporated to dryness. The solid was re-
dissolved in CH2Cl2 and flashed over a short pad of silica gel. Drying in
vacuo provided a green powder (123 mg, 0.17 mmol, 52%). Green crys-
tals suitable for X-ray analysis were obtained by layering pentane over a
concentrated solution of 2 in CH2Cl2 at À368C. 1H NMR (300.13 MHz,
CDCl3, 258C): d = 17.49 (s, 1H; Ru=CHAr), 7.46 (dd, 1H; aromatic
CH), 7.18 6.95 (5H; aromatic CH), 6.86 (dd, 1H; aromatic CH), 6.73 (d,
1H; aromatic CH), 4.74 (septet, 1H; (CH3)2CHOAr), 4.12 (s, 4H;
N(CH2)2N), 2.55 2.15 (m, 18H; mesityl CH3), 1.25 (d, 3H;
(CH3)2CHOAr), 1.04 (d, 3H; (CH3)2CHOAr); 13C NMR (75.47 MHz,
CDCl3, 258C): d = 313.8, 207.1, 152.1, 144.9, 139.4, 139.1, 138.8, 138.0,
136.8, 135.8, 131.6, 130.3, 128.8, 128.4, 121.7, 119.1, 114.9, 111.9, 74.7,
51.4, 49.4, 24.6, 20.2, 19.2, 19.0, 17.8, 17.2, 16.8; FT-IR (ATR-mode): n˜ =
2963 (br), 2915 (br), 1584 (s), 1479 (s), 1444 (s), 1389 (w), 1325 (w), 1261
(s), 1229 (w), 1190 (vs), 1100 (s), 1003 (vs), 934 (w), 848 (w), 801 (s), 749
(s), 697 cmÀ1 (w); elemental analysis calcd for C32H38ClF3N2O4RuS
(740.24): C 51.92, H 5.17, N3.78; found C 47.20, H 5.83, N2.86.
Experimental Section
General: NMR data were obtained at 300.13 MHz for proton and at
75.74 MHz for carbon in the indicated solvent at 258C on a Bruker Spec-
trospin 300 and are listed in parts per million downfield from tetrame-
thylsilane for proton and carbon. IR spectra were recorded on a Bruker
Vector 22 using ATR technology. GC-MS investigations were carried out
on a Shimadzu GCMS-QP5050, using a SPB-5 fused silica gel column
(30 mî0.25 mmî25 mm film thickness). Elemental analyses were carried
out at the Mikroanalytical Laboratory, Anorganisch-Chemisches Institut,
TU M¸nchen, Germany, and at the Institute of Physical Chemistry, Uni-
versity of Vienna, Austria. A Jobin Yvon JY 38 plus was used for ICP-
OES measurements, a MLS 1200 mega for microwave experiments. Syn-
theses of the ligands and catalysts were performed under an argon atmos-
phere by standard Schlenk techniques or in an N2-mediated dry-box
(Labmaster 130, MBraun, Germany) unless stated otherwise. Reagent
grade diethyl ether, pentane, THF, and toluene were distilled from
sodium/benzophenone under argon. Reagent grade dichloromethane was
distilled from calcium hydride under argon. Other solvents and reagents
were used as purchased. Deionized water was used throughout. Diethyl
diallylmalonate (DEDAM), 1,7-octadiene, diallyl ether, N,N-diallyltri-
fluoroacetamide, diallyldiphenylsilane, methyl trans-3-pentenoate, tert-
butyl N,N-diallycarbamate, ethyl vinyl ether (EVE), [RuCl2(=CHPh)-
(IMesH2)(PCy3)] (IMesH2 = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroi-
midazol-2-ylidene), CF3SO3Ag, CF3COOAg, PS-DVB-CH2-OH (100 300
mesh, 1.7 mmol Ar-CH2-OHgÀ1, 1% crosslinked), perfluoroglutaric an-
hydride, salicylaldehyde, 2-propyliodide, norborn-5-ene-2,3-dimethanol,
and 7-oxanorborn-5-ene-2,3-dicarboxylic anhydride were purchased from
Fluka (Buchs, Switzerland). [RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)],[19] di-
ethyl diallylmalonate[29] and diethyl dimethallylmalonate[23] were pre-
pared according to the literature. A ruthenium standard containing 1000
ppm of ruthenium was purchased from Alfa Aesar/Johnson Matthey
(Karlsruhe, Germany).
[Ru(CF3CO2)2(=CH-o-iPr-O-C6H4)(IMesH2)] (3): Under dry glovebox
conditions, [RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)] (200 mg, 0.319 mmol)
was dissolved in THF (10 mL) and a solution of CF3CO2Ag (2 equiv, 141
mg, 0.64 mmol) in THF (2 mL) was slowly added to the stirred solution.
Stirring was continued for 20 minutes. A color change from green to lilac
and the formation of a precipitate were observed. The precipitate was fil-
tered off and the solution evaporated to dryness. It was redissolved in
CH2Cl2 (1 mL), flashed over 5 cm silica gel and evaporated to dryness,
giving a lilac powder (177 mg, 0.23 mmol, 71%). Lilac crystals suitable
for X-Ray analysis were obtained by layering pentane over a dilute solu-
tion of 3 in Et2O at À368C. 1H NMR (300.13 MHz, CDCl3, 258C): d =
17.38 (s, 1H; Ru=CHAr), 7.28 (dd, 1H; aromatic CH), 7.08 (s, 4H; mesi-
tyl aromatic CH), 7.00 (dd, 1H; aromatic CH), 6.86 (dd, 1H; aromatic
CH), 6.56 (d, 1H; aromatic CH), 4.55 (septet, 1H; (CH3)2CHOAr), 4.05
(s, 4H; N(CH2)2N), 2.37 (s, 6H; mesityl p-CH3), 2.20 (s, 12H; mesityl o-
CH3), 0.88 (d, 6H; (CH3)2CHOAr); 13C NMR (75.47 MHz, CDCl3,
258C): d = 314.7, 209.1, 159.0, 152.1, 142.4, 138.4, 137.9, 133.4, 129.2,
128.7, 122.6, 121.8, 111.2, 109.9, 73.2, 50.3, 24.6, 19.1, 16.8; FT-IR (ATR-
mode): n˜ = 2982 (br), 2925 (br), 1698 (s), 1609 (w), 1593 (w), 1577 (w),
1478 (w), 1451 (w), 1393 (s), 1260 (s), 1180 (vs), 1141 (vs), 1033 (w), 937
(w), 877 (s), 844 (s), 812 (w), 780 (w), 748 (s), 722 cmÀ1 (s); elemental
analysis calcd for C35H38F6N2O5Ru (781.75): C 53.77, H 4.90, N3.58;
found: C 53.63, H 4.90, N3.63.
Heterogenization on a polystyrene-divinylbenzene support, generation of
[Ru(polymer-CH2-O-CO-CF2-CF2-CF2-COO)(CF3CO2)(=CH-o-iPr-O-
C6H4)(IMesH2)] (4) and [RuCl(polymer-CH2-O-CO-CF2-CF2-CF2-
COO)(=CH-o-iPr-O-C6H4)(IMesH2)] (5): PS-DVB-CH2-OH (1.00 g) was
suspended in dry THF (20 mL) and of perfluoroglutaric anhydride (1
equiv, 377 mg, 1.70 mmol) was added. Stirring was continued for 2 h,
then the product was filtered and washed three times with THF. It was
dried under high vacuum giving a white solid (1.33 g). FT-IR (ATR-
mode): n˜ = 3025 (br), 2920 (br), 2442 (br), 1772 (vs), 1600 (br), 1489
(w), 1448 (w), 1375 (w), 1312 (s), 1245 (s), 1175 (vs), 1145 (vs), 1044 (s),
915 (w), 867 (w), 823 (w), 755 (s), 697 cmÀ1 (vs). The solid was resuspend-
ed in THF (10 mL) and excess NaOH (140 mg in 30 mL water) was
added. The mixture was stirred for 2 h, the product was filtered and
washed three times with water. The precipitate was suspended in water
(20 mL) and AgNO3 (1.2 equiv, 350 mg, 2.1 mmol) in water (10 mL) was
added. Stirring was continued for 2 h, the product was filtered and
washed three times each with water, Et2O, and pentane. Drying in vacuo
gave a white solid (0.85 g). FT-IR (ATR-mode): n˜ = 3056 (br), 3023 (br),
2918 (br), 2854 (br), 2336 (br), 1808 (w), 1596 (w), 1490 (w), 1446 (w),
1364 (w), 1285 (w), 1216 (s), 1067 (w), 1027 (w), 896 (w), 840 (w), 812
(w), 754 (s), 694 cmÀ1 (vs). The solid was resuspended in THF (25 mL)
and [RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)] (99.8 mg, 0.159 mmol) was
added. Stirring was continued for 90 min. [RuCl(polymer-CH2-O-CO-
[Ru(CF3SO3)2(=CH-o-iPr-O-C6H4)(IMesH2)] (1): Under glovebox condi-
tions [RuCl2(=CH-o-iPr-O-C6H4)(IMesH2)] (200 mg, 0.32 mmol) was dis-
solved in THF (10 mL) and a solution of CF3SO3Ag (2 equiv, 164 mg,
0.64 mmol) in THF (2 mL) was slowly added to the stirred solution. Stir-
ring was continued for 3 h. A color change from green to red and the for-
mation of a precipitate were observed. The precipitate was filtered off
and the solution evaporated to dryness. The solid was redissolved in
CH2Cl2 and flashed over a short pad of silica gel. Drying in vacuo provid-
ed a green powder (152 mg, 56%, 0.18 mmol). 1H NMR (300.13 MHz,
CDCl3, 258C): d = 18.49 (s, 1H; Ru=CHAr), 7.51 (dd, 1H; aromatic
CH), 7.10 7.19 (5H; aromatic CH), 6.97 (dd, 1H; aromatic CH), 6.78 (d,
1H; aromatic CH), 4.72 (septet, 1H; (CH3)2CHOAr), 4.16 (s, 4H;
N(CH2)2N), 2.38 (m, 12H; mesityl o-CH3), 2.17 (s, 6H; mesityl p-CH3),
1.11 (d, 6H; (CH3)2CHOAr); 13C NMR (75.47 MHz, CDCl3, 258C): d =
332.4, 203.9, 154.0, 145.5, 139.9, 138.6, 136.8, 135.1, 132.5, 130.8, 129.1,
122.1, 118.6, 114.4, 112.2, 52.1, 49.6, 24.8, 20.4, 19.4, 17.8, 17.1; FT-IR
(ATR-mode): n˜ = 2962 (br), 2910 (br), 1587 (s), 1481 (s), 1447 (s), 1331
(s), 1259 (vs), 1233 (w), 1190 (vs), 1088 (vs), 1015 (vs), 983 (s), 932 (w),
864 (w), 796 (vs), 754 (w), 696 cmÀ1 (w); elemental analysis calcd for
782
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 777 784

Ruthenium-Based Metathesis Catalysts
777 784
CF2-CF2-CF2-COO)(=CH-o-iPr-O-C6H4)(IMesH2)] (5) was filtered off,
washed with THF, and dried in vacuo to yield an off-white powder. FT-
IR (ATR-mode): n˜ = 3057 (w), 3024 (w), 2917 (br), 2848 (w), 1600 (w),
1492 (w), 1451 (w), 1420 (w), 1180 (br), 1154 (w), 1027 (w), 1014 (w), 906
(w), 841 (w), 751 (s), 697 cmÀ1 (vs). CF3COOAg (1 equiv, 35.2 mg, 0.159
mmol) was dissolved in THF (2 mL) and the solution was added to 5, dis-
solved in THF (10 mL), and the mixture was stirred for 90 min. Extensive
washing with THF and drying in vacuo gave [Ru(polymer-CH2-O-CO-
CF2-CF2-CF2-COO)(CF3CO2)(=CH-o-iPr-O-C6H4)(IMesH2)] (4) as a lilac
powder (0.7 g). Ru content 0.18 mmolgÀ1, corresponding to 160 mg cata-
lystgÀ1 (16% catalyst loading). FT-IR (ATR-mode): n˜ = 3060 (w), 3023
(w), 2919 (br), 2852 (w), 2378 (w), 1942 (w), 1874 (w), 1805 (w), 1595
(w), 1488 (w), 1447 (w), 1365 (br), 1185 (br), 1019 (w), 817 (w), 754 (s),
695 cmÀ1 (vs).
orine atoms of the CF3 groups and the methyl parts of the isopropyl
group are 2:1 disordered. Relevant crystallographic data are summarized
in Tables 1 3.
CCDC-215892 (2) and -215891 (3) contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK;
fax: (+44)1223 336033; or email: deposit@ccdc.cam.ac.uk.
Acknowledgements
Financial support provided by the Austrian Science Fund (FWF Vienna,
project Y-158) and the Freistaat Bayern is gratefully acknowledged. We
wish to thank M. Barth, Anorganisch-chemisches Institut, TU Munich,
for carrying out elemental analyses.
2-Isopropoxystyrene (6): Salicylaldeyde (10.3 g, 84 mmol), NBu4Br (25.1
g, 78 mmol), and iPrI (20 mL, 0.2 mol) were dissolved in CH2Cl2 (300
mL). NaOH (3.5 g, 88 mmol) dissolved in water (150 mL) was slowly
added to the stirred solution. After stirring for 2 d, the organic phase was
separated and the aqueous phase was washed with CH2Cl2 (3î50 mL).
The combined organic phase was dried in vacuo, redissolved in ethyl ace-
tate, and filtered. The filtrate was dried over Na2SO4 and evaporated to
dryness, giving a yellow oil (5.7 g). MePPh3Br (13 g, 34.7 mmol) was
dried in a Schlenk tube and put under argon. Dry THF (50 mL) was
added, followed by nBuLi (2n in pentane, 17.4 mL, 34.7 mmol) at 08C. It
was stirred for 30 minutes at 08C and another 30 minutes at room tem-
perature. The aldehyde (5.7 g, 34.7 mmol) was slowly added at 08C and
stirring was continued for 12 h. Water (5 mL) was added to the yellow
solution, which was then dried in vacuo. The product was extracted with
Et2O (3î25 mL), dried over Na2SO4, and evaporated to dryness. Column
chromatography over silica gel using ethyl acetate/pentane (2:98) as
eluent provided the product in the first fraction (Rf = 0.5). It was dried
over Na2SO4 and evaporated to dryness to give the product as a clear
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1
liquid (3.2 g, 20 mmol, 23%). H NMR (300.13 MHz, CDCl3, 258C): d =
7.37 (d, 1H; Ar), 7.07 (m, 1H; Ar), 6.97 (dd, 1H; CH), 6.76 (m, 2H;
Ar), 5.63 (dd, 1H; trans-CHCH2), 5.12 (dd, 1H; cis-CHCH2), 4.40 (sept,
1H; CH(CH3)2), 1.21 (d, 6H; CH(CH3)2); 13C NMR (75.47 MHz, CDCl3,
258C): d = 155.0, 131.9, 128.6, 127.7, 126.4, 120.5, 114.0, 70.6, 22.1; FT-
IR (ATR-mode): n˜ = 2978 (s), 2933 (br), 1625 (w), 1597 (w), 1484 (s),
1453 (s), 1383 (w), 1290 (w), 1240 (vs), 1118 (s), 997 (w), 955 (w), 906
(w), 751 cmÀ1 (w); GC-MS: calcd for C11H14O: 162.1, found 162.1 [M]+.
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RCM-, ring-opening cross metathesis and enyne-metathesis experiments
(slurry reactions): The following procedure is representative of all experi-
ments. DEDAM (520 mg, 2.16 mmol) was dissolved in CH2Cl2 (2 mL)
and the homogeneous catalyst (0.01 0.10 mol% as indicated in Table 4)
or supported catalyst (12.0 mg) was added. The reaction mixture was
heated to 458C for 2 h. After removal of the catalyst by filtration, the
1
yield was determined by GC-MS and H NMR spectroscopy in CDCl3.
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Leaching of the support: Aqua regia (3.0 mL) was added to the com-
bined effluents from which the solvent was removed. The mixture was
placed inside high-pressure Teflon tubes and leaching was carried out
under microwave conditions (50, 600, and 450 W pulses, respectively, t =
32 minutes). After cooling to room temperature, the mixture was filtered
and water was added up to a volume of 10.00 mL.
Ru measurements: Ru was measured by ICP-OES (l = 240.272 nm, ion
line). The background was measured at l = 240.287 and 240.257 nm.
Standardization was carried out with Ru standards containing 0, 5, and
10 ppm of Ru.
X-ray measurement and structure determination of 2 and 3: The data col-
lection was performed on a Nonius Kappa CCD equipped with graphite-
monochromatized MoKa radiation (l = 0.71073 ä) and a nominal crystal
to area detector distance of 36 mm. Intensities were integrated using
DENZO and scaled with SCALEPACK.[30] Several scans in f and w di-
rection were made to increase the number of redundant reflections,
which were averaged in the refinement cycles. This procedure replaces in
a good approximation an empirical absorption correction. The structures
were solved with direct methods SHELXS86 and refined against F2
SHELX97.[31] All non-hydrogen atoms were refined with anisotropic dis-
placement parameters. Hydrogen atoms were refined at calculated posi-
tions with isotropic displacement parameters, except the hydrogen atoms
at C(1), which were found and refined normally. For compound 2 the flu-
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783
Chem. Eur. J. 2004, 10, 777 784
www.chemeurj.org
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

O. Nuyken, M. R. Buchmeiser et al.
FULL PAPER
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[31] G. M. Sheldrick, Program package SHELXTL V.5.1, Bruker Analyt-
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Received: April 9, 2003
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Revised: July 24, 2003 [F5031]
784
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Chem. Eur. J. 2004, 10, 777 784