Facile synthesis of effcient and selective ruthenium olefin metathesis catalysts with sulfonate and phosphate ligands

Article abstract of DOI:10.1021/om1007924

A series of novel, air-stable ruthenium NHC catalysts with sulfonate and phosphate anions have been prepared easily in one pot at high yields using commercially available precursors. The catalysts were found to be effective for ring-opening metathesis polymerization, ring-closing metathesis, and cross-metathesis. The catalysts showed higher cis-selectivity in olefin cross-metathesis reactions as compared to earlier known ruthenium-based olefin metathesis catalysts, with allylbenzene and cis-1,4-diacetoxybutene as substrates.

Full text of DOI:10.1021/om1007924

Organometallics 2010, 29, 6045–6050 6045
DOI: 10.1021/om1007924
Facile Synthesis of Effcient and Selective Ruthenium Olefin Metathesis
Catalysts with Sulfonate and Phosphate Ligands
Peili Teo and Robert H. Grubbs*
Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical
Engineering, California Institute of Technology, Pasadena, California 91125, United States
Received August 14, 2010
A series of novel, air-stable ruthenium NHC catalysts with sulfonate and phosphate anions have been
prepared easily in one pot at high yields using commercially available precursors. The catalysts were found
to be effective for ring-opening metathesis polymerization, ring-closing metathesis, and cross-metathesis.
The catalysts showed higher cis-selectivity in olefin cross-metathesis reactions as compared to earlier known
ruthenium-based olefin metathesis catalysts, with allylbenzene and cis-1,4-diacetoxybutene as substrates.
Introduction
catalysts has a tendency to give highE/Z ratios (>6) at conver-
sions >75%.15-17 Although phosphine-based catalysts give
lower E/Z ratios than their NHC counterparts, they tend to
decompose at conversions no more than 60%.15 A highly
Z-selective molybdenum catalyst has been recently developed
by Hoveyda and Schrock.18-20 These very important catalysts
should have numerous applications.18-21 However, as has
been seen in the past, ruthenium-based catalysts can be more
applicable in many situations. Although there are some ruthe-
nium-based catalysts in recent literature that give better E/Z
ratios than the more traditional catalysts, they are generally
much less active.22 Other catalysts tend to have poor control
over selectivity at high conversions as a result of secondary
metathesis.16 The precatalysts themselves are also difficult to
prepare with multistep synthesis and very low yields, making
them less commercially viable. Z-Olefins are commonly found
in natural products, and the ability to form Z-olefins from a
single catalytic process remains important to synthetic organic
chemistry.1 Hence, there remains an urgent need to develop
tolerant catalysts that enable high conversions while delivering
low E/Z ratios for production of Z-olefins.
Olefin metathesis has become a standard method in the
formation of C-C double bonds.1,2 In particular, olefin cross-
metathesis (CM) is a convenient route to functionalize higher
olefins from simple precursors. CM has gained prominence
due to the availability of catalysts of varying activities such
as the phosphine-based3-6 and the N-heterocyclic carbene
(NHC)-based Ru catalysts7,8 and the molybdenum/tungsten-
based catalysts.9-11 However, application of cross-metathesis
has been relatively limited when compared to ring-opening
metathesis polymerizations (ROMP) and ring-closing metath-
esis (RCM).12-14 This is a result of poor stereoselectivity of the
olefin products at high conversions. Z-Selectivity is usually
compromised at high conversions, where current ruthenium
*To whom correspondence should be addressed. E-mail: rhg@
caltech.edu.
(1) Handbook of Metathesis; Grubbs, R. H., Ed.; Wiley VCH: Weinheim,
Germany, 2003; Vols. 1-3.
(2) Olefin Metathesis and Metathesis Polymerization; Ivin, K. J.; Mol,
J. C., Eds.; Academic Press: San Diego, CA, 1997.
(3) Schwab, P.; France, M. B.; Ziller, J. W.; Grubbs, R. H. Angew.
Chem., Int. Ed. 1995, 34, 2039.
(4) Schwab, P.; Grubbs, R. H.; Ziller, J. W. J. Am. Chem. Soc. 1996,
118, 100.
(5) Schwab, P.; France, M. B.; Ziller, J. W.; Grubbs, R. H. Angew.
Many metathesis catalysts based on the [L2X2RudCHR]
scaffold have been synthesized in an effort to increase catalyst
stability, activity, and selectivity.3-5,7,8,12-17,22-24 However, most
efforts were concentrated on the modifications of the L2 units
or R group.23,25-28 Chen et al. has very recently reported the use
Chem. 1995, 107, 2179.
(6) Belderrain, T. R.; Grubbs, R. H. Organometallics 1997, 1997, 4001.
(7) Scholl, S.; Ding, S.; Lee, C. W.; Grubbs, R. H. Org. Lett. 1999, 1, 953.
(8) Sanford, M. S.; Love, J. A.; Grubbs, R. H. J. Am. Chem. Soc.
2001, 123, 6543.
(9) Schrock, R. R.; Murdzek, J. S.; Bazan, G. C.; Robbins, J.;
Dimare, M.; O’Regan, M. B. J. Am. Chem. Soc. 1990, 112, 3875.
(10) Bazan, G. C.; Kosravi, E.; Schrock, R. R.; Feast, W. J.; Gibson,
V. C.; O’Regan, M. B.; Thomas, J. K.; Davis, W. M. J. Am. Chem. Soc.
1990, 112, 8378.
(18) Flook, M. M.; Jiang, A. J.; Schrock, R. R.; Muller, P.; Hoveyda,
A. H. J. Am. Chem. Soc. 2009, 131, 7962.
(19) Ibrahem, I.; Yu, M.; Schrock, R. R.; Hoveyda, A. H. J. Am.
Chem. Soc. 2009, 131, 3844.
(20) Schrock, R. R. Chem. Rev. 2009, 109, 3211.
(21) Courchay, F. C.; Sworen, J. C.; Wagener, K. B. Macromolecules
2003, 36, 8231.
(11) Bazan, G. C.; Oskam, J. H.; Cho, H. N.; Park, L. Y.; Schrock,
R. R. J. Am. Chem. Soc. 1991, 113, 6899.
(22) Rosen, E. L.; Sung, D. H.; Chen, Z.; Lynch, V. M.; Bielawski,
C. W. Organometallics 2010, 29, 250.
(23) Szadkowska, A.; Makal, A.; Wozniak, K.; Kadyrov, R.; Grela,
(12) Furstner, A. Angew. Chem. 2000, 112, 3013.
(13) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2004, 34, 18.
(14) Kotha, S.; Screenicasachary, N. Ind. J. Chem. B 2001, 40, 763.
(15) Ritter, T.; Hejl, A.; Wenzel, A. G.; Funk, T. W.; Grubbs, R. H.
Organometallics 2006, 25, 5740.
(16) Anderson, D. R.; Ung, T.; Mkrtumyan, G.; Bertrand, G.;
Grubbs, R. H.; Schrodi, Y. Organometallics 2008, 27, 563.
(17) Vehlow, K.; Maechling, S.; Blechert, S. Organometallics 2006,
25, 25.
K. Organometallics 2009, 28, 2693.
(24) Bornand, M.; Torker, S.; Chen, P. Organometallics 2007, 26, 3585.
(25) Keitz, B. K.; Grubbs, R. H. Organometallics 2010, 29, 403.
(26) Vougioukalakis, G. C.; Grubbs, R. H. Chem. Rev. 2010, 110,
1746.
(27) Keitz, B. K.; Grubbs, R. H. J. Am. Chem. Soc. 2009, 131, 2038.
(28) Lichtenheldt, M.; Wang, D.; Vehlow, K.; Reinhardt, I.; Kuhnel, C.;
Decker, U.; Blechert, S.; Buchmeiser, M. R. Chem.;Eur. J. 2009, 15, 9451.
r
2010 American Chemical Society
Published on Web 10/25/2010
pubs.acs.org/Organometallics

6046 Organometallics, Vol. 29, No. 22, 2010
Scheme 1. Standard Olefin Cross-Metathesis Reaction Using [Ru] Catalysts
Teo and Grubbs
Scheme 2. Synthesis of Catalysts Initiators 4-14 from 1-3
of phosphinephenoxide and sulfoxide anionic ligands to con-
trol stereoselectivity in ROMP of norbornene/cyclooctene.29
Buchmeiser et al. has also reported the use of triflate and
trifluoroacetate anions as ligands for Ru complexes for RCM
and enyne metathesis reactions.30 To the best of our knowledge,
there have been no other reports on the successful modification of
the anions (X2) for improved E/Z selectivities in olefin metathesis
reactions, especially in CM reactions.26,27,31-33 Anion modifica-
tion is mostly done by replacing a chloride anion by an aryloxide
attached to the NHC or PR3 itself. These NHCs or phosphine
ligands, however, are often difficult to synthesize, resulting
in poor yields of the ligand itself and the final precatalysts
prepared.26 Herein, we report a series of air-stable and easy-to-
prepare ruthenium olefin metathesis catalysts bearing bulky
sulfonate or phosphate ligands with significantly improved
Z-selectivity in CM reactions (eq 1) over other known Ru-based
olefin metathesis catalysts.
Figure 1. Schematic drawing of metallacycle formation for
formation of (a) Z-olefin and (b) E-olefin.
by the bulky sulfonate or phosphate ligand to improve catalytic
activity, as substitution of both chlorides by bulky anionic
ligands would slow the reaction dramatically (vide infra).
Formation of a small amount of dianion exchanged product
is inevitable, and their presence in small quantities (<20%)
serves to prevent the catalysts from scrambling back to form
their precursors.29 As such, except for (H2IMes)(MesSO3)2Rud
CHPh(OiPr), 15, which exists as a pure compound, all other
complexes (4-14) exist in a mixture of monosulfonate and
disulfonate complexes, with the disulfonate complex being a
minor component in the mixture. The composition of disulfo-
nate complexes in the product mixture can be controlled by
careful control of reaction times and amounts of silver sulfonate
used. Microanalytical data for the complexes were not prepared
as a result of the mixture of products. These complexes also exist
as a mixture of diastereoisomers, especially complexes 4, 7, and
13, which also contain rotamers due to the free rotation of the o-
Results and Discussion
It is envisioned that the installation of bulky groups on the
anionic ligands on the Ru catalysts would force the resultant
metallacyclobutane transition state to adopt a cis-conforma-
tion, thereby resulting in the preferential production of cis-
olefins (Figure 1).29 Standard ligand exchange reactions
using various silver sulfonate or phosphate salts in a benzene
solution of the corresponding Ru precursors result in the forma-
tion of the desired metal complexes. The products can be isolated
in high yields (>75%) by simple filtration to remove the AgCl
byproduct and unreacted silver salts followed by subsequent
removal of solvents (eq 2). Only one chloride ligand is replaced
1
Tol groups on the NHC, resulting in extremely complex H
NMR spectra for these three complexes. All the complexes are
stable in air except for complex 13 (X=binapthylphosphate),
whose solution decomposes after standing in air for ∼30 min.
ROMP Activity. The ROMP of strained olefinic ring sys-
tems is one of the earliest industrial applications of olefin
metathesis and remains a popular tool for modern polymer
synthesis.1,2 Catalysts 4-14 were all highly effective in poly-
merizing norbornene. The E/Z ratio of poly(norbornene) using
4-14 does not vary much from that of their precursors, the
dichloride catalysts, 1-3(E/Z∼0.65). Catalyst 15 was very slow
(29) Torker, S.; Muller, A.; Chen, P. Angew. Chem., Int. Ed. 2010, 49,
3762.
(30) Krause, J. O.; Nuyken, O.; Wurst, K.; Buchmeiser, M. R.
Chem.;Eur. J. 2004, 10, 777.
(31) Giudici, R. E.; Hoveyda, A. H. J. Am. Chem. Soc. 2007, 129,
3824.
(32) Veldhuizen, J. J. v.; Campbell, J. E.; Giudici, R. E.; Hoveyda,
A. H. J. Am. Chem. Soc. 2005, 127, 6877.
(33) Occhipinti, G.; Bjorsvik, H.-R.; Tornroos, K. W.; Furstner, A.;
Jensen, V. R. Organometallics 2007, 26, 4383.

Article
Organometallics, Vol. 29, No. 22, 2010 6047
Table 1. CM Reaction Data for Catalysts 1-14a
cat.
R1
R2
R3
Xd
timeb
conv/%e
E/Z
1
2
3
4
5
6
7
8
Me
Me
iPr
Me
Me
iPr
H
H
Me
H
H
Me
H
H
H
H
Me
H
Cl
Cl
Cl
MesSO3
MesSO3
MesSO3
TripSO3
TripSO3
p-TolSO3
NapSO3
5
5
5
87
87
97
74
70
78
78
80
75
72
73
83
74
71
9.6
10.1
6.3c
3.3
3.1
2.7
3.6
3.0
3.1
6.2
3.0
5.5
4.0
3.0
Me
iPr
H
Me
iPr
H
15
25
240
30
75
60
15
45
10
120
90
Me
iPr
iPr
iPr
Me
iPr
Me
H
9
iPr
10
11
12
13
14
Me
iPr
Me
Me
iPr
CamSO3
(PhO)2PO2
BINAPPO4
BINAPPO4
Me
H
H
iPr
a All reactions were carried out at 23 °C using 1 mol % catalyst loading
and C6H6 solvent, 0.2 M solution. Ratios and conversions are determined by
gas chromatography. b Time of reaction in minutes. c Secondary metathesis
reaction continues rapidly for catalyst 3to give E/Z of 9.7 at 92% conversion
(lower conversion) after 10 min of reaction. d MesSO3: mesitylsulfonate
(2,4,6-C6H2(Me)3SO3); TripSO3: 2,4,6-triisopropylbenzenesulfonate (2,4,6-
C6H2(iPr)3SO3); p-TolSO3: p-tolylsulfonate; NapSO3: 1-napthylsulfonate;
CamSO3: camphorsulfonate; (PhO)2PO2: diphenylphosphate; BINAPPO4:
S-1,10-binapthylphosphate. e All reactions were run to maximum conversion
possible for each catalyst with best E/Z ratio for conversions >70% shown.
Figure 2. RCM conversion of DEDAM (18) substrate using
catalysts 4-14. Conditions were 1 mol % catalyst, 0.1 M in
substrate C6D6 at 30 °C.
to initiate under standard ROMP conditions15 and achieved
only 70% conversion after 6 h.
13 and 14. Attempts to prepare the BINAPPO4 complex from 2
were futile due to rapid product decomposition. Similar pro-
blems were faced during the preparation of the TripSO3,
p-TolSO3, and CamSO3 analogues from 2.
RCM Activity. Given the good activity of catalysts 1-14 in
ROMP, we next focused on testing their activity in RCM,
which is generally more demanding to the catalyst than ROMP.1
A standard reaction for testing the RCM activity of a particular
catalyst is the ring closing of diethyl diallyl malonate (DEDAM, 18)
to the cyclopentene (19)15 (Figure 2). Catalysts 9 (X=p-tolyl
sulfonate) and 11 (X=camphorsulfonate) were extremely effec-
tive for RCM, where complete conversion was attained within
30 min of substrate addition at just 1 mol % catalyst loading,
30 °C. 13 (X=binapthylphosphate) gave very poor conversions
in the RCM reaction (50% conversion in 7 h), possibly due to
rapid decomposition of the catalyst upon initiation.
CM Activity. Our initial studies show that when the
mesitylsulfonate ligand is coupled with a bulky NHC such
as 1,3-diisopropylphenyl-4,5-dihydroimidazol-2-ylidene on
Ru (complex 6), the lowest E/Z ratio of 2.7 at high conver-
sions of >70% (78%) can be attained. This is considerably
lower than any of the Ru precursors or even that attainable
using the phosphine-based catalysts.15 Although catalysts
with similar E/Z selectivities have been reported prior to this
work, higher catalyst loadings and harsher reaction conditions
are required.17 6 also displays a relatively linear relationship
between conversion and E/Zratio, which is mostly not observed
in all other NHC-based Ru catalysts due to secondary metath-
esis reactions by the catalysts under high olefin product con-
centrations. When olefin 17 is reacted with 1 mol % of 5,theE/Z
ratio of 17 changed by <2% in 1 h and <10% in 3 h (cf. E/Z
increased by 20% when 17 is reacted with 2 for 30 min). The
lower tendency to carry out the secondary metathesis by the
sulfonate catalysts as compared to their dichloride precursors
not only enables the formation of more cis-olefin cross-products
but also maintains the low E/Z ratios over time.
It is not unexpected that the CM reactions using the
dianion-exchanged complexes, such as a disulfonate, were
extremely slow. This is largely due to the extreme steric
bulkiness of both anions resulting in slow catalyst initiation.
Among the sulfonate catalyst initiators, the 1-napthylsulfo-
nate complex (10) is the fastest to initiate. However, when
both the chlorides are replaced by 1-napthylsulfonate, cata-
lyst initiation dropped dramatically (5 mol %, 23 °C, 19%
conversion, 24 h). This highlights the point that the presence
of a small amount of the disubstituted product (<20%) in
the catalyst used does not contribute much to the overall
catalytic activity of the monosubstituted complexes. Simi-
larly, when the H2IMesRu precursor (2) is coupled with two
mesitylsulfonate anions, Ru complex 15 was obtained.
Although complex 15 was not as active as its monoanion-
exchanged analogue (5), it gave much lower E/Z ratio for the
CM reaction (5 mol %, 34% conversion, E/Z 1.1, 24 h). The
crystal structure of 15 revealed a Ru center with two faces
blocked by the bulky mesityl groups of the mesitylsulfonate
anions; thus the steric hindrance around the Ru is the likely
cause for the lower catalyst activity. On the other hand, with
the two large mesityl groups blocking two faces at the
bottom, the formation of trans-olefins would be less favored.
During the attempts to find the optimum balance between
catalyst activity and Z-selectivity, we found that doping of 15
with its monosulfonate analogue, 5, helped to improve the
overall activity while maintaining the Z-selectivity of 15.
When 15 was doped with 15% of 5 to enhance its activity (5
being more active but less selective), net conversion and E/Z
ratio were improved using lower catalyst loading and shorter
time (2.5 mol %, 30% conversion, E/Z 0.9, 6 h, 50 °C).
However, catalyst decomposition prevented higher yields of
17 from being obtained. Increasing the dopant amount to
∼30% resulted in reaction profiles similar to that of 5 due to
the dominance of catalytic activity by the dopant (5), which is
highly active even in small amounts (30% doping of a 2.5 mol
Besides arylsulfonates, the use of alkylsulfonates such as
CamSO3 (complex 11) may also improve the Z-selectivity in
the CM reaction. The binapthylphosphate-based (BINAPPO4)
catalysts, 13 and 14, also show significant improvements in the
Z-selectivities relative to their precursors, despite being slightly
less selective when compared to the sulfonate-based catalysts.
Secondary metathesis reactions were also minimal when using

6048 Organometallics, Vol. 29, No. 22, 2010
Teo and Grubbs
under a nitrogen atmosphere. All solvents and C6D6 used for
NMR data collection were purified by passage through solvent
purification columns and further degassed with bubbling argon.34
2,4,6-Triisopropylbenzenesulfonyl chloride was purchased from
TCI America, and diphenylphosphate and (S)-1,10-binapthylpho-
sphate were purchased from Alfa Aesar. All other reagents were
purchased from Aldrich. 2,4,6-Triisopropylbenzenesulfonic acid
was prepared according to literature procedures.35 Catalysts 1-3
were obtained from Materia Inc. Commercially available reagents
were used as received with the following exceptions. Allylbenzene,
tridecane, and cis-1,4-diacetoxy-2-butene were distilled from anhy-
drous potassium carbonate and stored under argon in Schlenk
flasks. 1H and 13C spectra were recorded on a Varian 500 spectro-
meter, and the chemical shifts are reported in ppm relative to the
appropriate solvent. Reaction conversions for RCM reactions
were obtained by comparing the integral values of starting material
and product, and no internal standard was used. High-resolution
mass spectra were provided by the California Institute of Technol-
ogy Mass Spectrometry Facility. Gas chromatography data were
obtained using an Agilent 6850 FID gas chromatograph equipped
with a DB-Wax polyethylene glycol capillary column (Agilent).
Conversions for ROMP and RCM reactions were determined by
integration of the olefin proton signals in their 1H NMR spectra.
Conversions and E/Z ratios for CM reactions were determined by
comparing GC data using tridecane as an internal standard
following literature procedures.15 X-ray crystallographic struc-
tures were obtained by Larry M. Henling and Dr. Michael W.
Day of the California Institute of Technology Beckman Institute
X-ray Crystallography Laboratory.
Figure 3. Ball-and-stick model of 15 (hydrogen atoms not
shown for clarity).
˚
Table 2. Selected Bond Lengths (A) and Bond Angles (deg) for
Complex 15
Ru(1)-C(22)
Ru(1)-C(1)
Ru(1)-O(2)
Ru(1)-O(5)
Ru(1)-O(1)
1.8222(17)
1.9871(17)
2.0525(11)
2.0533(11)
2.2490(11)
C(22)-Ru(1)-C(1)
C(22)-Ru(1)-O(2)
C(1)-Ru(1)-O(2)
C(22)-Ru(1)-O(5)
C(1)-Ru(1)-O(5)
O(2)-Ru(1)-O(5)
C(22)-Ru(1)-O(1)
C(1)-Ru(1)-O(1)
O(2)-Ru(1)-O(1)
O(5)-Ru(1)-O(1)
100.06(7)
102.11(6)
93.37(6)
98.70(6)
94.45(5)
156.11(5)
79.66(6)
178.90(6)
87.74(4)
84.55(4)
Representative Procedure for RCM Kinetics. In a glovebox,
catalysts 4-14 (0.8 μmol) were dissolved in C6D6 (0.75 mL) and
placed in a NMR tube equipped with a rubber septum. The NMR
tube was removed from the glovebox, and DEDAM (19.3 μL,
0.08 mmol) was injected, after which the tube was immediately
placed in the spectrometer and a spectral array started by arraying
the “pad” variable for Varian spectrometers.
% catalyst loading is equivalent to 0.8 mol % loading of 5).
i
Larger anions such as Pr3PhSO3 do not give disubstituted
Representative Procedure for CM Kinetics. To a flame-dried
1-dram vial, 2.0 μmol of catalyst was added in the glovebox
followed by the addition of 1.0 mL of C6D6. Allylbenzene (1.00 mL,
7.55 mmol) and tridecane (0.920 mL, 3.77 mmol) were combined in
a flame-dried, 1-dram vial under an atmosphere of argon. The
mixture was stirred before taking a t0 time point. cis-1,4-Diacetoxy-
2-butene (64 μL, 0.40 mmol) and the allylbenzene/tridecane mixture
(51 μL; 0.20 mmol 15 þ 0.10 mmol of tridecane)15 were then added
via syringe. The reaction was allowed to stir at 23 °C. Aliquots were
taken at the specified time periods. Samples for GC analysis were
obtained by adding a ca. 60 μL reaction aliquot to 500 μL of a 3 M
solution of ethyl vinyl ether in dichloromethane. The samples was
shaken, allowed to stand for 1 min, and then analyzed via GC. All
reactions were performed in duplicate to confirm reproducibility.
GC retention times were as follows (min): allylbenzene (10.87),
tridecane (11.55), cis-diacetoxybutene (18.13), trans-diacetoxybu-
tene (18.70), cis-17 (21.27), trans-17 (21.48), trans-homocoupled
allylbenzene (24.09), cis-homocoupled allylbenzene (24.34).
General Synthesis of Silver Sulfonates and Silver Phosphates.
The sulfonic acid or hydrogen phosphate (2.5 mmol) was dissolved
in the minimal quantity of water required to ensure complete
dissolution of all solids. Na2CO3 (1.25 mmol) was added to the solu-
tion, and the mixture stirred until effervescence subsided. AgNO3
(2.5 mmol) was added to precipitate out the silver salt, and the
mixture filtered. The residue was washed with a small amount of
cold water and dried under high vacuum overnight at 60 °C.
Synthesis of 4 and 7. 1 (23 mg, 0.04 mmol) was dissolved in
benzene (8 mL) in a 20 mL scintillation vial, and RSO3Ag(0.2mmol)
was added to the solution. The mixture was stirred for 5 h, then
filtered through a plug of Celite to yield a yellow solution. The
complexes, and the di-pTolSO3 complexes from both pre-
cursors 2 and 3 decompose rapidly upon catalyst initiation.
Carrying out the CM reaction with pure 15 at high
temperature (80 °C) resulted in selectivities close to that of
5 but better, which is likely to be a result of ligand dissocia-
tion due to heating (2.5 mol %, 5 min, 90% conversion, E/Z
2.9). This is, however, the best selectivity achieved by the Ru
catalysts for such high conversions. The higher activity and
Z-selectivity of 15 as compared to 6 also makes 15 a more
attractive catalyst (cf. 6: 90% conversion, 8 h, E/Z 3.2).
Preparation of 15 is also much more straightforward, where
2 is simply reacted with a large excess of silver mesitylsulfo-
nate and the silver chloride, together with unreacted silver
sulfonate, and filtered off upon complete reaction, followed
by solvent removal to obtain 15 as a crystalline solid.
Conclusions
We have presented here a series of novel air-stable catalyst
initiators for olefin metathesis reactions that are more
Z-selective in CM reactions as compared to the currently
known Ru olefin metathesis catalysts. Although these systems
do not meet the levels of Z-selectivity of the best Mo catalysts,
their ease of preparation and utilization should make them
useful for a number of applications. These initiators can be
easily prepared in one pot from inexpensive commercially
available materials.
Experimental Section
(34) Love., J. A.; Morgan, J. P.; Trnka, T. M.; Grubbs, R. H. Angew.
Chem. Intl. Ed. 2002, 41, 4035.
(35) Jautze, S.; Peters, R. Angew. Chem. Int. Ed. 2008, 47, 9284.
General Information. All reactions unless otherwise stated are
carried out in dry glassware in a Vacuum Atmospheres glovebox

Article
Organometallics, Vol. 29, No. 22, 2010 6049
solvent was removed under vacuum to yield 4 (24 mg, 82%) and 7
(28 mg, 85%) as yellow solids. 4 and 7 exist as multiple diastere-
omers, resulting in complex 1H NMR spectra.36 4: 1H NMR
(C6D6): δ 17.51 (s, 1H), 17.50 (s, min), 8.59 (br s, 1H), 7.44-6.5
(m, 14H), 4.23 (sept, maj, J= 6 Hz, 1H), 4.15 (sept, min, J=6Hz),
4.08 (sept, min, J = 6 Hz), 3.76-3.68 (m, 2H), 2.63 (s, 3H), 2.58 (br
s, 3H), 2.54 (s, 2H), 2.51 (br s, 3H), 2.38 (br s), 2.24 (s), 2.17 (s), 1.92
(s), 1.88(s,3H),1.81(s,3H),0.97(d,J=6 Hz, 1H), 0.93 (d, J=10 Hz,
1H), 0.89 (d, J=6 Hz, 1H), 0.83 (d, J=6 Hz, 1H). 13C NMR: δ
304.8, 275.0, 210.0, 152.9, 144.0, 143.5, 143.2, 141.9, 140.3, 140.0,
139.9, 139.7, 139.5, 139.4, 139.1, 139.0, 138.1, 137.9, 137.7, 137.4,
137.3, 137.1, 122.2, 121.9, 121.6, 112.6, 112.1, 87.8, 74.3, 69.6, 68.7,
51.5, 22.5, 21.5, 21.0, 20.9, 20.3, 20.2, 19.3, 18.6. HR-MS (FAB):
calcd 734.1520, found 734.1541.
Table 3. Relevant Crystallographic Data for Complexes 15
empirical formula
temperature (K)
fw
cryst syst
space group
unit cell dimens
C49H60N2O7S2Ru CH2Cl2
100(2)
1039.11
monoclinic
C(2)/c
42.4711(19)
10.8253(5)
23.4557(11)
90
115.674(2)
90
9719.4(8)
8
1.420
0.571
4336
108 685
0.17 ꢀ 0.16 ꢀ 0.13
-63 e h e 62,
-16 e k e 15,
-31 e l e 34
0.0528, 0.0653
0.0367, 0.0641
1.242 and -1.395
3
ꢀ
˚
a (A)
ꢀ
˚
b (A)
ꢀ
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
V (A )
ꢀ
˚
Z
Dcalc (mg/m3)
absorb coeff (mm-1
F(000)
no. of reflns
cryst size (mm3)
index ranges
7: yellow solid (29 mg, 91%). 1H NMR: δ 17.5 (s, maj), 17.6
(s, min), 8.66 (d, J = 10 Hz), 8.51 (d, J = 6 Hz), 7.4-7.0 (m), 6.45
(d, J = 6 Hz), 6.29 (d, J = 8 Hz), 4.9 (br s), 4.32-4.27 (m), 4.10-
4.05 (m), 3.84-3.71 (m), 2.92 (s), 2.68-2.57 (m), 2.54 (s), 2.51 (s),
2.27 (s), 1.19 (s), 1.74 (s), 1.36 (d, J = 6 Hz), 1.24 (d, J = 6.5 Hz),
1.2-1.04 (m). 7 decomposed in solution during data collection for
13C, resulting in an extremely complicated 13C spectrum. HR-MS
(FAB): calcd 819.2537, found 819.2562.
)
R, wR2 (all data)
final R, wR2 (for I >2σ)
largest diff peak and
Synthesis of 5. 2 (25 mg, 0.04 mmol) was dissolved in CH2Cl2
(8 mL) in a 20 mL scintillation vial, silver mesitylsulfonate
(MesSO3Ag) (15 mg, 0.048 mmol) was added, and the mixture
was stirred overnight. Half an equivalent of MesSO3Ag (6 mg,
0.02 mmol) was added again, and the mixture was stirred over-
night, then filtered through a plug of Celite to afford a brown
filtrate. The filtrate was evaporated to dryness under high vacuum
to give a brown solid (23 mg, 73%). 5 contains 15% disulfonate
-3
ꢀ
˚
hole (e A
)
128.2, 122.9, 122.2, 121.3, 121.2, 111.2, 73.7, 33.0, 28.0, 27.0, 26.5,
24.4, 23.0, 22.6, 22.5, 20.4, 19.3, 12.9. HR-MS (FAB): calcd
958.4024, found 958.4019.
Synthesis of 9. 3 (28 mg, 0.04 mmol) was dissolved in benzene
(8 mL) in a 20 mL scintillation vial, p-TolSO3Ag (50 mg, 0.18
mmol) was added, and the mixture was stirred overnight. The
mixture was then filtered over a plug of Celite to afford a yellow-
green filtrate. The filtrate was evaporated to dryness under high
vacuum to give a light green solid (29 mg, 85%). 9exists as a mixture
of inseparable mono- and disulfonate complexes in a 5:2 mixture.
1HNMR(C6D6):δ18.32 (s, min), 17.18 (s, maj, 1H), 7.42-6.22 (m,
13H), 4.52 (sept, J = 6.5 Hz, 1H), 4.10 (sept, J = 6.5 Hz, min), 3.48
(sept, J = 6.5 Hz, 4H), 3.82-3.78 (m, 2H), 3.6-3.57 (m, 2H), 1.56
(d, J = 6.5 Hz, 6H), 1.43 (d, J = 6.5 Hz, 4H), 1.26 (m, 14 H), 1.16
(d, J = 6.5 Hz, 6H). 13C NMR (C6D6): δ 306.7, 275.7, 210.0, 156.5,
154.3, 149.0, 148.1, 146.9, 145.4, 145.1, 138.7, 137.1, 135.6, 131.5,
130.4, 130.2, 125.8, 125.6, 125.2, 124.5, 124.0, 123.2, 123.1, 121.0,
114.7, 114.4, 114.0, 78.3, 55.2, 29.5, 29.3, 29.0, 26.9, 26.5, 24.7, 24.0,
23.9, 22.2, 20.7, 20.3. HR-MS (FAB): calcd 675.2656, found
675.2682 ([9 - p-TolSO3-]þ).
Synthesis of 10. 2 (25 mg, 0.04 mmol) was dissolved in CH2Cl2
(8 mL) in a 20 mL scintillation vial, silver napthylsulfonate
(NapSO3Ag) (15 mg, 0.048 mmol) was added, and the mixture
was stirred overnight under a nitrogen atmosphere. The mixture
was then filtered through a plug of Celite to afford a light green
filtrate. The filtrate was evaporated to dryness under high vacuum to
give a green solid (27 mg, 80%). 10 exists as a mixture of inseparable
mono- and disulfonate complexes in a 5:1 mixture. 1HNMR(C6D6):
δ 18.80 (s, min), 17.76 (s, maj), 8.97 (d, J = 10 Hz, maj), 8.73 (d, J =
10 Hz, min), 7.64-6.66(m),5.89(d,J=10Hz,maj), 6.02(d,J=10
Hz, min),4.27(s), 3.49-3.31 (m), 2.71 (s, maj), 2.67 (s, min), 2.54 (s),
2.40 (s, maj), 2.34 (s, min), 2.27 (s, maj), 2.24 (s, min), 1.32 (d, J = 6
Hz, min), 1.11(d, J= 10Hz, min), 0.98 (d, J=6Hz), 0.71 (d, J =6
Hz), 0.47 (d, J = 10 Hz). 13C NMR (C6D6): δ 309.6, 275.7, 210.9,
153.1, 145.5, 142.1, 141.7, 141.1, 140.4, 139.3, 138.9, 138.5, 138.2,
134.3, 131.5, 130.9, 130.5, 130.4, 130.3, 130.1, 130.0, 129.9, 129.8,
127.3, 126.9, 126.7, 126.6, 126.2, 126.1, 124.8, 124.6, 123.3, 122.7,
113.7, 75.8, 75.2, 52.6, 50.5, 21.5, 21.1, 20.5, 20.3, 20.1, 19.4, 19.2,
19.0. HR-MS (FAB): calcd 798.1833, found 798.1862.
1
complex. H NMR (C6D6): δ 18.83 (s, min), 17.79 (s, maj, 1H),
7.85 (dd, J = 1.5, 7.5 Hz, 1H), 7.55-6.86 (m, 10H), 4.22-4.13 (m,
6H), 2.58 (br s, 3H), 2.25 (br s, 9H), 2.18 (br s, 5H), 2.09 (s, 7H),
2.07 (s, 3H), 1.43 (d, J = 6 Hz, 6H). 13C NMR (C6D6): δ 310.8,
250.0, 209.4, 190.2, 160.8, 152.9, 145.1, 139.05, 138.7, 138.4, 137.9,
137.6, 137.4, 137.3, 135.7, 130.4, 130.2, 130.0, 129.9, 129.7, 129.2,
128.3, 126.5, 125.8, 122.8, 120.4, 114.0, 113.4, 75.2, 75.3, 22.7, 22.2,
21.1, 20.9, 20.4. HR-MS (FAB): calcd 790.2146, found 790.2110.
Synthesis of 6. 3 (28 mg, 0.04 mmol) was dissolved in benzene
(8 mL) in a 20 mL scintillation vial, MesSO3Ag (25 mg, 0.08 mmol)
was added, and the mixture was stirred overnight. The same
amount of silver salt was added each day after, for two days, and
the mixture was filtered over a plug of Celite to afford a yellow
filtrate. The filtrate was evaporated to dryness under high vacuum
to give a yellow solid (26 mg, 73%). 6 contains 10% disulfonate
complex. 1H NMR (C6D6): δ 18.47 (s, min), 17.97 (s, 1H), 7.43-
7.05 (m, 12H), 3.88 (s, 4H), 4.20 (sept, J = 6.5 Hz, 1H), 4.01 (br m,
2H), 3.30 (sept, 2H), 2.55 (s, 2H), 2.33 (s, 7H), 1.31 (d, J = 6.5 Hz,
10H), 1.14 (d, J = 6.5 Hz, 14H). 13C NMR (C6D6): δ 305.3, 275.0,
214.6, 153.147.0, 144.0, 139.3, 138.5, 138.3, 137.8, 137.7, 137.4,
135.0, 130.9, 130.4, 129.6, 129.5, 129.2, 124.7, 124.3, 123.8, 122.9,
122.1, 112.8, 74.7, 53.8, 28.7, 28.2, 27.1, 25.5, 23.7, 22.7, 21.3, 20.7,
20.3. HR-MS (FAB): calcd 874.3085, found 874.3120.
Synthesis of 8. 3 (28 mg, 0.04 mmol) was dissolved in benzene
(8 mL) in a 20 mL scintillation vial, TripSO3Ag (61 mg, 0.2 mmol)
was added, and the mixture was stirred overnight. The same
amount of silver salt was added each day after, for two days, and
the mixture was filtered over a plug of Celite to afford a yellow
filtrate. The filtrate was evaporated to dryness under high vacuum
1
to give a yellow solid (33 mg, 87%). H NMR (C6D6): δ 18.14
(s, 1H), 7.42-7.04 (m, 10H), 6.59 (t, J=7.5 Hz, 1H), 6.38 (d, J=
6.5 Hz, 1H), 4.51 (sept, J=6.5 Hz, 1H), 4.07 (sept, J=6.5 Hz, 3H),
3.80 (br m, 4H), 2.7 (sept, J = 6.5 Hz, 1H), 1.82 (br s, 6H), 1.31 (d,
J = 6.5 Hz, 5H), 1.25 (d, J = 6.5 Hz, 10H), 1.21 (d, J = 6.5 Hz,
7H), 1.14 (d, J = 6.5 Hz, 10H), 1.11 (d, J = 6.5 Hz, 10H). 13C
NMR (C6D6): δ 304.0, 273.9, 214.2, 151.7, 148.8, 147.9, 135.2,
Synthesis of 11. 3 (28 mg, 0.04 mmol) was dissolved in benzene
(8 mL) in a 20 mL scintillation vial, silver (-)-camphor-10-sulfonate
(CamSO3Ag) (95 mg, 0.28 mmol) was added, and the mixture was
stirred overnight. The mixture was filtered over a plug of Celite to
afford a yellow filtrate. The filtrate was evaporated to dryness under
high vacuum to give a yellow solid (25 mg, 70%). 11 contained 30%
(36) Stewart, I. C.; Benitez, D.; O’Leary, D. J.; TKatchouk, E.; Day,
M. W.; Goddard, W. A., III; Grubbs, R. H. J. Am. Chem. Soc. 2009, 131,
1931.

6050 Organometallics, Vol. 29, No. 22, 2010
Teo and Grubbs
disulfonate. 1H NMR (C6D6): δ 18.32 (min, s), 17.18 (maj, s, 1H),
7.41-7.00 (m, 10H), 4.53 (sept, maj, J = 6.5 Hz, 1H), 4.10 (sept,
min, J = 6 Hz), 3.91-3.76 (m, 4H), 3.62 (br s, 1H), 3.58 (br s, 1H),
3.48 (sept, J = 7 Hz, 4H), 1.56 (d, J = 7 Hz, 6H), 1.49 (d, J = 7 Hz,
4H), 1.43 (d, J = 6.5 Hz, 3H), 1.26 (m, 13H), 1.16, (d, J = 7 Hz,
4H), 1.07 (d, J = 7 Hz, 7H), 0.96 (m, 6H). 13C NMR (C6D6): δ
306.0, 275.0, 209.3, 153.6, 148.3, 147.4, 146.2, 144.7, 137.9, 136.4,
134.9, 130.8, 129.6, 129.5, 125.1, 124.9, 124.5, 123.8, 123.3, 122.5,
122.4, 120.3, 114.0, 77.6, 54.2, 28.8, 28.6, 28.3, 26.2, 26.1, 25.8, 24.0,
23.3, 23.1, 21.5, 20.0, 19.6. HR-MS (FAB): calcd 675.2656, found
675.2653 ([11 - CamSO3-]þ).
6.00 (d, J = 15 Hz), 4.66 (sept, J = 11 Hz), 3.73 (br m), 1.76 (d,
J = 10 Hz), 1.64 (br s), 1.37-0.85 (m), 0.67 (br m), 0.43 (br m).
13C NMR (C6D6): δ 310.7, 299.5, 275.0, 215.3, 214.2, 213.7,
154.5, 153.6, 153.5, 149.9, 149.2, 149.1, 148.8, 146.1, 145.6,
145.0, 133.1, 132.8, 132.6, 132.4, 131.3, 131.2, 130.9, 130.7,
130.2, 130.1, 130.0, 129.9, 129.8, 129.6, 129.4, 129.3, 129.2,
126.9, 125.9, 125.8, 124.5, 122.6, 122.4, 122.0, 121.9, 121.8,
121.7, 121.3, 113.5, 113.4, 112.5, 76.0, 75.4, 74.8, 54.5, 29.8,
29.0, 28.8, 28.6, 28.3, 26.7, 26.3, 23.5, 23.4, 21.4, 21.0, 20.8,
20.6, 20.4, 19.9, 19.6. HR-MS (FAB): calcd 1022.313, found
1022.316.
Synthesis of 12. 2 (25 mg, 0.04 mmol) was dissolved in benzene
(8 mL) in a 20 mL scintillation vial, (PhO)2PO2Ag (23 mg,
64 mmol) was added, and the mixture was stirred overnight. The
mixtures were then filtered over a plug of Celite, and the filtrate
was evaporated to dryness under high vacuum to give a green
solid (28 mg, 82%). 12 exists as a mixture of mono- and dipho-
Synthesis of 15. 2 (25 mg, 0.04 mmol) was dissolved in CHCl3
(8 mL) in a 20 mL scintillation vial, MesSO3Ag (98 mg, 0.32
mmol) was added, and the mixture was stirred overnight. The
mixture was filtered to afford a dark brown filtrate, and the
filtrate was evaporated to dryness under high vacuum to give a
1
dark brown solid (31 mg, 80%). H NMR (C6D6): δ 18.82 (s,
1
sphate complexes in a 5:1 mixture. H NMR (C6D6): δ 18.41
1H), 7.45-6.78 (m, 11H), 6.29 (d, J = 8 Hz, 1H), 4.30 (s, 2H),
4.13 (sept, J = 6 Hz, 1H), 4.78 (s, 4H), 2.56 (br s, 9H), 2.42 (br s,
8H), 2.30 (s, 5H), 2.28 (s, 5H), 1.94 (s, 9H), 0.86 (d, J = 6 Hz,
6H). 13C NMR (C6D6): δ 323.8, 209.3, 155.3, 145.5, 141.2, 139.6,
139.1, 138.9, 138.4, 138.3, 137.9, 134.2, 131.3, 131.2, 131.0,
130.9, 130.5, 130.3, 129.7, 129.2, 127.5, 127.3, 123.6, 122.6,
114.0, 75.9, 53.7, 52.7, 50.2, 30.5, 23.5, 21.5, 21.0, 20.5, 20.3,
19.4. HR-MS (FAB): calcd 954.2886, found 954.2896.
Crystal Structure Determinations. Crystals were mounted on a
glass fiber using Paratone oil, then placed on the diffractometer
under a nitrogen stream at 100 K. Refinement of F2 is done
against all reflections. The weighted R-factor (wR) and goodness
of fit (S) are based on F2. Conventional R-factors (R) are based
on F, with F set to zero for negative F2. The threshold expression
of F2 > 2σ(F2) is used only for calculating R-factors(gt), etc.,
and is not relevant to the choice of reflections for refinement. R-
Factors based on F2 are statistically about twice as large as those
based on F, and R-factors based on ALL data will be even larger.
All esd’s (except the esd in the dihedral angle between two least-
squares planes) are estimated using the full covariance matrix.
The cell esd’s are taken into account individually in the estima-
tion of esd’s in distances, angles, and torsion angles; correlations
between esd’s in cell parameters are used only when they are
defined by crystal symmetry. An approximate (isotropic) treat-
ment of cell esd’s is used for estimating esd’s involving least-
squares planes.
(s, min), 17.59 (s, maj, 1H), 7.20-6.63 (m), 6.41 (d, J=4 Hz, min),
6.34 (d, J=9 Hz, maj, 1H), 4.71 (sept, J=6 Hz, min), 4.48 (sept,
J=6 Hz, maj, 1H), 3.42 (br s, 6H), 2.75 (br s, 3H), 2.65 (br s),
2.49 (br s), 2.59 (br s, 3H), 2.26 (br m, 12H), 1.24 (m). 13C
NMR (C6D6): δ 303.1, 275.5, 211.7, 210.4, 154.5, 153.9, 153.8,
153.7, 153.6, 153.5, 146.1, 141.9, 141.5, 140.4, 139.2, 138.9,
134.4, 134.1, 130.3, 130.2, 130.0, 129.7, 123.5, 123.4, 122.8,
122.7, 121.0, 120.8, 113.8, 113.6, 76.4, 75.8, 52.6, 50.7, 21.5,
21.4, 21.1, 20.8, 19.9, 18.9. HR-MS (FAB): calcd 840.2033,
found 840.2063.
Synthesis of 13. 1 (23 mg, 0.04 mmol) was dissolved in benzene
(8 mL) in a 20 mL scintillation vial, and silver binapthylpho-
sphate (BINAPPO2Ag) (40 mg, 88 mmol) was added to the solu-
tion. The mixture was stirred for 5 h, then filtered through a plug of
Celite to yield a yellow solution. The solvent was removed under
vacuum to yield a yellow solid (32 mg, 92%). 1H NMR (CD2Cl2): δ
17.44, 17.10, 8.46-6.86 (m), 4.86 (m), 4.75 (m), 4.51-3.73 (m), 2.65
(br s), 2.54 (br s), 2.37 (s), 2.29 (br s), 2.28 (br s), 1.24 (d, J = 6 Hz),
1.15 (d, J = 6 Hz), 1.08 (d, J = 6 Hz), 0.80 (d, J = 6 Hz), 0.78 (d,
J = 6 Hz). HR-MS (FAB): calcd 882.1564, found 882.1563. 13
exists as a large mixture of diastereomers, resulting in an extremely
1
complicated H NMR spectrum. The solution sample of 13 also
decomposed during data collection for 13C, resulting in the inability
to collect an accurate 13C spectrum for 13.
Synthesis of 14. 3 (28 mg, 0.04 mmol) was dissolved in benzene
(8 mL) in a 20 mL scintillation vial, BINAPPO2Ag (50 mg, 0.18
mmol) was added, and the mixture was stirred overnight. The
mixture was then filtered over a plug of Celite to afford a yellow
filtrate. The filtrate was evaporated to dryness under high
vacuum to give a yellow solid (26 mg, 62%). 14 exists as a
mixture of mono- and diphosphate complexes in a 1:1 mixture.
1H NMR (C6D6): δ 19.07 (di-), 17.85 (min, mono-), 17.72 (maj,
mono), 7.68-6.65 (m), 6.48 (d, J = 15 Hz), 6.13 (d, J = 15 Hz),
Acknowledgment. We thank K. Endo for helpful dis-
cussions. P.T. is grateful to A*STAR Singapore for a
postdoctoral fellowship and NSF for a research grant.
Supporting Information Available: This material is available
free of charge via the Internet at http://pubs.acs.org.