Ruthenium olefin metathesis catalysts containing six-membered sulfone and sulfonamide chelating rings

Article abstract of DOI:10.1021/om101129b

The preparation and X-ray structure characterization of new olefin metathesis initiators containing sulfone- and sulfonamide-substituted benzylidene ligands are described. We observed that these catalysts exhibit Ru???O(SO)R interactions, forming six-memb

Full text of DOI:10.1021/om101129b

1130 Organometallics 2011, 30, 1130–1138
DOI: 10.1021/om101129b
Ruthenium Olefin Metathesis Catalysts Containing Six-Membered
Sulfone and Sulfonamide Chelating Rings
†
†,‡
‡
‡
_
ꢀ
Anna Szadkowska, Karolina Zukowska, Aleksandra E. Pazio, Krzysztof Wozniak,
Renat Kadyrov,§ and Karol Grela*,†,‡
†Institute of Organic Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland,
‡
_
Department of Chemistry, University of Warsaw, Zwirki i Wigury Street 101, 02-089 Warsaw, Poland, and
§Evonik Degussa GmbH, 097-12a Rodenbacher Chaussee 4, 63457 Hanau-Wolfgang, Germany
Received December 1, 2010
The preparation and X-ray structure characterization of new olefin metathesis initiators contain-
ing sulfone- and sulfonamide-substituted benzylidene ligands are described. We observed that these
catalysts exhibit Ru O(SO)R interactions, forming six-membered chelates. Tuning the electronic
and steric factors of the benzylidene part as well as selecting the proper NHC ligands can have a direct
impact on catalyst activity and stability, leading to promising new catalysts.
3 3 3
1. Introduction
resulting products and are tuning the existing ruthenium
complexes to specific requirements of technological pro-
cesses (Figure 1).4,5 A great deal of research is directed
toward catalysts designed especially to be used at low load-
ings and in environmentally friendly solvents.6,7
Recently, our group introduced the stable sulfur Hoveyda-
type derivatives VII and IX, which demonstrate some fine-
tuning abilities.8,9 Independently, Lemcoff disclosed VIII,
The metathesis reaction is among the most useful C-C
bond-forming transformations, as it can provide valuable
intermediates for the synthesis of specialty chemicals and
bioactive or natural products.1,2 It is well-known that ruthe-
nium alkylidene complexes are reasonably tolerant to air and
moisture.3 Although a broad variety of different metathesis
initiators have been created, it is still expected that their
impact on fine chemical production will increase. Many
research groups and industrial companies continue to ex-
plore possible improvements in the attainable turnover
number, catalyst loading, and metal impurities in the
ꢀ
(5) (a) Clavier, H.; Caijo, F.; Borre, E.; Rix, D.; Boeda, F.; Nolan,
S. P.; Mauduit, M. Eur. J. Org. Chem. 2009, 4254–4265. (b) Slugovc, C.;
Perner, B.; Stelzer, F.; Mereiter, K. Organometallics 2004, 23, 3622–
3626. (c) Slugovc, C.; Burtscher, D.; Mereiter, K.; Stelzer, F. Organo-
metallics 2005, 24, 2255–2258. (d) Burtscher, D.; Perner, B.; Mereiter,
K.; Slugovc, C. J. Organomet. Chem. 2006, 691, 5423–5430. (e)
ꢀ
*To whom correspondence should be addressed. Tel: þ48-22-343-
2106. Fax: þ48-22-632-66-81. E-mail: klgrela@gmail.com.
Szadkowska, A.; Gstrein, X.; Burtscher, D.; Jarzembska, K.; Wozniak,
K.; Slugovc, C.; Grela, K. Organometallics 2010, 29, 117–124. (f) Vieille-
Petit, L.; Clavier, H.; Linden, A.; Blumentritt, S.; Nolan, S. P.; Dorta, R.
Organometallics 2010, 29, 775–788.
(1) (a) Handbook of Metathesis; Grubbs, R. H., Ed.; Wiley-VCH:
Weinheim, Germany, 2003. (b) Trnka, T. M.; Grubbs, R. H. Acc. Chem.
Res. 2001, 34, 18–29. (c) Connon, S. J.; Blechert, S. Angew. Chem. 2003,
115, 1944-1968; Angew. Chem., Int. Ed. 2003, 42, 1900-1923. (d)
Astruc, D. New J. Chem. 2005, 29, 42–56. (e) Clavier, H.; Grela, K.;
Kirschning, A.; Mauduit, M.; Nolan, S. P. Angew. Chem. 2007, 119,
6906-6922; Angew. Chem., Int. Ed. 2007, 46, 6786-6801. (f) Colacino,
J.; Martinez, E.; Lamaty, F. Coord. Chem. Rev. 2007, 251, 726–764. (g)
Bieniek, M.; Michrowska, A.; Usanov, D. L.; Grela, K. Chem. Eur. J.
2008, 14, 806–818.
(6) (a) Michrowska, A.; Guzajski, Ł.; Kaczmarska, Z.; Mennecke, K.;
Kirschning, A.; Grela, K. Green Chem. 2006, 8, 685–688. (b) Michrowska,
A.; Grela, K. Pure Appl. Chem. 2008, 80, 31–43. (c) Burtscher, D.; Grela, K.
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A.; Naroznik, J.; Kaczmarska, Z.; Rupnicki, L.; Grela, K. ChemSusChem
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(7) (a) Binder, J. B.; Guzei, I. A.; Rainers, R. T. Adv. Synth. Catal.
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Grela, K. Organometallics 2009, 28, 2693–2701. (b) Szadkowska, A.;
Grela, K. Curr. Org. Chem. 2008, 12, 1631–1647.
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(4) (a) Bieniek, M.; Bujok, R.; Cabaj, M.; Lugan, N.; Lavigne, G.;
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(9) (a) Kadyrov, R.; Rosiak, A.; Tarabocchia, J.; Szadkowska, A.;
Bieniek, M.; Grela, K. New Concepts in Designing Ruthenium based
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r
pubs.acs.org/Organometallics
Published on Web 02/18/2011
2011 American Chemical Society

Article
Organometallics, Vol. 30, No. 5, 2011 1131
Figure 1. Selected Ru catalysts for olefin metathesis.
Scheme 1. Synthetic Pathway to Sulfone Ligands Containing
tert-Butyl and Phenyl Groupsa
showing that the complex is highly tunable and reaching the
conclusion that it is the cis isomer of VII.10 Later, in a joint
project, the kinetics of VII f VIII isomerization was studied
by us.11 The promising features of the catalysts shown, such
as excellent thermodynamic and air stability combined with
good catalytic activity at elevated temperatures, motivated
us to direct our research into developing other ligands for
ruthenium initiators based on a sulfone chelating motif. We
became interested in determining whether an oxidation of
the sulfur atom from SII (VII) and SIV (IX) to the þ6
oxidation state would give viable catalyst precursors. While
the previously prepared initiators VII and IX were rather
latent in nature because they possess a strong five-membered
Ru S chelating ring, we envisioned that the new complexes
stabilized via weaker six-membered Ru O chelation
3 3 3
3 3 3
should exhibit a much higher initiation rate. Additionally,
we decided to explore the NHC ligand influence on the
stability of these complexes.
a Reagents and isolated yields: (a) t-BuOH, H2SO4/H2O, -10 °C f
room temperature, 24 h (58%). (b) C6H5I, CuI, sodium tert-butoxide,
neocuproine, toluene, reflux, 24 h, (65%); (c) Oxone, MeOH, 5 °C f
room temperature, 4 h (3a, 75%; 3b, 76%);14 (d) Pd(PPh3)2Cl2,
CH2dCHBF3K, Cs2CO3, THF/H2O, 85 °C, 22 h (4a, 80%; 4b, 82%).
2. Results and Discussion
Synthesis and Characterization of New Complexes. During
previous research on IX, we realized that the steric bulk of the
substituent at sulfur directly influences the catalyst activity.
The same observation was made earlier by Lemcoff during
his detailed study on differently substituted cis isomers of
complex VIII.10 Our starting point was to check the respec-
tive steric and electronic influences of the R substituents at
the sulfur atom on the stability and activity of the relevant
initiators. For the preparation of the required ligand pre-
cursors, we used synthetic pathways similar to those
exploited in the case of sulfoxide complexes IX in our
previous contributions. The commercially available 2-bro-
mothiophenol (1) was transformed into sulfone-bearing
ligand precursors 4a,b by oxidation of sulfides 2a,b with
2 equiv of Oxone12 and Suzuki-Miyaura cross-coupling
with potassium (vinyl)trifluoroborate as the key steps
(Scheme 1).13
Having the ligands in hand, we made attempts to form
complexes, first containing t-Bu substituents to cause steric
hindrance. At the same time, we were prompted to evaluate
the possible influence of the nature of the NHC on the
behavior of these complexes. In the first attempt to form
complexes containing a t-Bu substituent, Xa-XIIa, we chose
a standard ligand exchange reaction, which required using
different terms presented in Scheme 2. In the case of initiators
Xa and XIa, syntheses were performed in the presence of
(12) McCarthy, J. R.; Matthews, D. P.; Paolini, J. P. Organic
Syntheses; Wiley: New York, 1998; Collect. Vol. 9, p 446.
(13) Molander, G. A.; Brown, A. R. J. Org. Chem. 2006, 71, 9681–
9686.

1132 Organometallics, Vol. 30, No. 5, 2011
Szadkowska et al.
Scheme 2. New Ru Initiators with Sulfone Ligands Containing
tert-Butyl and Phenyl Groups
Scheme 3. Synthetic Pathway of a Sulfonamide bearing Precur-
sor 7 and Catalyst XIIc
Scheme 4. Synthesis of Catalyst XIIIa
CuCl, in toluene at 85 °C with indenylidene catalysts,15 while
the procedure developed for XIIa was based on the applica-
tion of more favorable and milder conditions (40 °C and
dichloromethane). As a ruthenium source we used SIPr
Gru;a derivative of Grubbs’ second-generation catalyst.
The SIPr NHC ligand is known to form very stable Ru
complexes.16 The corresponding products Xa and XIa were
isolated in rather poor yields (∼30%); however, to our
satisfaction, catalyst XIIa was formed in 57% yield as light
green microcrystals. The new ruthenium compound XIIa
was found to be stable in air as well in solution, which
allowed us to fully characterize it by spectral techniques
and elemental analysis.
Encouraged by these first successes, we decided to con-
tinue the preparation of analogous complexes bearing a
phenyl substituent at the sulfone group (Xb and XIb);
however, this turned out to be more problematic. During
the reaction between 4b and the appropriate indenylidene
ligands SIMes-Ind and IMes-Ind, we observed the initial
formation of green spots on the TLC plates which disap-
peared completely before SIMes Ind and IMes Ind were
consumed. Although syntheses of Xb and XIb ended up
unsuccessfully, in the case of XIIb we obtained the corre-
sponding sulfone catalyst in 51% yield, using the SIPr
Grubbs complex (SIPr Gru). We surmised that the stability
of SIPr-containing complexes XIIa,b is due to a combination
of steric hindrance at the benzylidene moiety with increased
steric bulk for the NHC ligand, which leads to more stable
initiators.
Next, we considered synthesizing a complex containing a
sulfonamide functionality at the benzylidene ligand. To
prepare ligand 7, we used a different protocol. The synthesis
began from the commercially available 2-bromobenzenesul-
fonamide 5, which was converted by alkylation17 and Suzu-
ki-Miyaura cross-coupling into compound 7 (Scheme 3).13
Taking into consideration the observed lower stability of
SIMes and IMes complexes, we decided to limit our synthesis
to a catalyst containing the SIPr ligand. We performed the
exchange reaction using the SIPr Grubbs catalyst (SIPr
Gru), which led to XIIc as dark green microcrystals in 52%
yield (Scheme 3).
Next, we synthesized a modification of the original archi-
tecture of catalyst XIIa, which led to the synthesis of initiator
XIIIa containing 3-bromopyridine as an additional labile
ligand.18 The complex XIIIa was prepared by adding an
excess of 3-bromopyridine (8) to XIIa. The reaction was
complete within 10 min, without the need to use any solvent
or column chromatography as a purification step. The best
way to obtain the analytically pure initiator XIIIa was to
(14) For other synthetic methods to obtain 3b, see: Truce, W. E.;
Amos, M. F. J. Am. Chem. Soc. 1951, 73, 3013–3017.
€
(15) (a) Furstner, A.; Grabowski, J.; Lehmann, C. W. J. Org. Chem.
1999, 64, 8275–8280. (b) Schanz, H.-J.; Jafarpour, L.; Stevens, E. D.;
Nolan, S. P. Organometallics 1999, 18, 5187–5190. (c) Jafarpour, L.;
Schanz, H.-J.; Stevens, E. D.; Nolan, S. P. Organometallics 1999, 18,
5416–5419.
(16) (a) Clavier, H.; Urbina-Blanco, A. C.; Nolan, S. P. Organome-
tallics 2009, 28, 2848–2854. (b) N-Heterocyclic Carbenes in Synthesis;
Nolan, S. P., Ed.; Wiley-VCH: Weinheim, Germany, 2006.
(17) To compare the analytical data of 6, see: Pines, S. H.; Purick,
R. M.; Reamer, R. A.; Gal, G. J. Org. Chem. 1978, 43, 1337–1342.
(18) The proposed modification was based on articles: (a) Love, J. A.;
Morgan, J. P.; Trnka, T. M.; Grubbs, R. H. Angew. Chem., Int. Ed. 2002,
41, 4035–4037. (b) Stanford, M. S.; Love, J. A.; Grubbs, R. H. Orga-
nometallics 2001, 20, 5314–5318.

Article
Organometallics, Vol. 30, No. 5, 2011 1133
Scheme 5. RCM of S1a
Figure 2. ADPs (atom displacement parameters) and labeling
of atoms in XIIIa. Hydrogen atoms are omitted for clarity.
Thermal ellipsoids are shown at the 30% probability level.
a Conditions: c[S1] =0.1M, 1mol%ofcatalyst, CD2Cl2, 22°C, 15 min.
precipitate it slowly from a mixture of dichloromethane and
n-heptane. The final light green microcrystalline solid was
isolated in 52% yield (Scheme 4).
Crystals suitable for X-ray diffraction studies were ob-
tained from a crystallization process at a temperature of
þ4 °C using the same system of solvents as for the precipita-
tion step with the addition of diethyl ether. This manipula-
tion allowed us to confirm the structure of XIIIa (Figure 2).
A single crystal of the compound XIIIa (Figure 2) grows
from a 1/1/1 DCM/diethyl ether/n-heptane mixture in the
triclinic P1 space group. There is one molecule of the catalyst
and two molecules of solvent in the independent part of the
unit cell. The molecules of solvents are diethyl ether and a
half-molecule of the n-heptane moiety (C200-C204 with the
C204 atom in the close neighborhood of the symmetry
center). The most important structural parameters for this
structure are given in Table 1. In comparison to earlier
presented structures containing the sulfur atom,8a the geo-
metry of this molecule is quite unique, due to significant
changes in the ruthenium coordination sphere. Because for
the first time the benzylidene ring is substituted by a sulfone
group, the ruthenium atom is coordinated by one of the
Scheme 6. RCM of S2a
oxygen atoms (O1). This creates
a
six-membered
Ru1-C22-C23-C28-S1-O1 ring with a Ru1-C22-
C23-C28 torsion angle value equal to -32.7(15)°, instead
of an almost planar five-membered ring, as in the Hoveyda
catalyst Ru1-C22-C23-C28-O13e and Ru1-C22-C23-
C28-S18 in the sulfur VII and sulfoxide IX derivatives of the
Hoveyda catalyst. Other significant geometry changes in-
clude Ru(1)-C(1) bond shortening and elongation of
Ru-Cl bonds (see Table 1), which can be justified also by
the presence of a 3-bromopyridyne ligand.
a Conditions: c[S2] =0.1M, 1mol%ofcatalyst, CD2Cl2, 22°C, 15 min.
Comparison of Catalyst in Tested Reactions. In order to
evaluate the catalytic performance of all initiators, a set of
model RCM reactions was carried out to picture structure
-activity relationships in the given class of the catalysts.
Activity profiles of complexes bearing the same benzylidene
ligand were used to establish a thorough evaluation of the
“NHC nature” effect. The model substrates selected by
us included various substituted and functionalized dienes
and enynes, and all reactions were run with 1 mol % of
initiator. At first, the reactivity profiles of these novel SO2-
Moreover, in the solid state the catalyst participates in
˚
stacking interactions at distances of 3.224-3.297 A, thus
forming some special catalyst-substituent-substituent-
catalyst associations (Figure 3). The interaction is enabled
by two 3-bromopyridine rings reversed and bound to differ-
ent molecules of catalyst. These “dimers” of the catalyst
molecules form planes in three dimensions, where the NHC
ligand domains (including the solvent molecules) are
threaded with the benzylidene-ruthenium-3-bromopyri-
dine domains.
1
chelating complexes were measured by H NMR spectros-
copy using common substrates: diethyl diallylmalonate (S1;
Scheme 5) and diethyl allyl(2-methylallyl)malonate (S2;
Scheme 6).

1134 Organometallics, Vol. 30, No. 5, 2011
Table 1. Comparison of Geometrical Parameters for Crystal Forms of Selected Structuresa
Szadkowska et al.
geometrical params
SIMes_S_iPr (VII)
IMes_SO_iPr (IX)
SiPr_SO2_tBu_Py (XIIIa)
˚
Bond Lengths (A)
Ru(1)-C(1)
2.054(1)
1.830(2)
2.440(1)
2.339(1)
2.338(1)
2.080(6)
1.841(7)
2.366(2)
2.334(4)
2.316(2)
1.985(9)
1.852(10)
2.245(7)
2.420(3)
2.361(3)
2.303(8)
1.463(13)
1.414(13)
1.756(10)
1.818(10)
1.457(7)
1.442(6)
Ru(1)-C(22)
Ru(1)-X(1)
Ru(1)-Cl(1)
Ru(1)-Cl(2)
Ru(1)-N(3)
C(22)-C(23)
C(23)-C(28)
S(1)-C(28)
S(1)-C(29)
S(1)-O(1)
1.460(2)
1.402(2)
1.778(2)
1.856(2)
1.457(9)
1.385(9)
1.775(7)
1.806(8)
S(1)-O(2)
1.486(5)
Planar Angles (deg)
Ru(1)-C(1)-N(1)
Ru(1)-C(1)-N(2)
Cl(1)-Ru(1)-Cl(2)
Ru(1)-C(22)-C(23)
C(1)-Ru(1)-X(1)
C(22)-C(23)-C(28)
N(3)-Ru(1)-C(22)
131.8(1)
120.6(1)
156.75(1)
122.8(1)
175.2(4)
119.1(1)
133.5(5)
123.4(4)
156.54(7)
124.6(5)
175.4(2)
118.4(6)
127.9(7)
126.4(7)
176.18(10)
126.3(7)
177.0(3)
126.9(9)
156.9(4)
Torsion Angles (deg)
C(28)-S(1)-O(1)-Ru(1)
C(22)-Ru(1)-O(1)-S(1)
C(22)-Ru(1)-S(1)-C(28)
Ru(1)-C(22)-C(23)-C(28)
C(13)-N(2)-C(1)-Ru(1)
C(4)-N(1)-C(1)-Ru(1)
1.9(7)
-29.1(6)
-16.4(1)
2.054(1)
1.830(2)
2.440(1)
-8.4(3)
-7.5(8)
14.3(9)
-32.7(15)
-7.2(16)
20.6(16)
-15.4(10)
a X(1) is the atom coordinated to the ruthenium center (S(1) for VII and IX and O(1) for XIIIa).
Figure 3. Dimer formed by two molecules of catalyst XIIIa and two molecules of 3-bromopyridine.
As expected, sulfone complexes XIIa, Xa, XIIIa, and XIIc,
bearing the saturated NHC SIPr and SIMes ligands, were
found to be more active than the XIa derivative containing
the unsaturated NHC (respectively 95% and 71%). Unfor-
tunately catalyst decomposition prevents achieving full con-
version, thus leaving unconverted S1. In the case of XIIb
(initiator with phenyl substituent), we assumed that despite
the presence of a more bulky ligand in the structure of the
catalyst, electronic factors caused instability of the complex
and, as a consequence, lower conversion during the catalytic
performance (75%). However, it is worth noting that all
initiators operate at room temperature in the RCM reaction
of S1, providing a very high yield of P1 in less than 10 min
(Scheme 5). For a better comparison, we imposed additional
reactivity data for the sulfur and sulfoxide congeners VII and
IX on the same graph. Previously, we indicated that these
ruthenium compounds showed a remarkable thermal stabi-
lity in different solvents, but it makes them useful only at

Article
Organometallics, Vol. 30, No. 5, 2011 1135
Table 2. Additional RCM and CM for New Initiatorsa
a Conditions: (RCM) c = 0.1 M, CH2Cl2; (CM) c = 0.2 M, CH2Cl2, 2 equiv of substrate S5a. Conversions were determined by GC for entries 1-5. In
case of entry 5, the yield after chromatographic purification is given (E/Z = 10/1).
higher temperature (from 80 to 110 °C).8 At the same time,
sulfone congeners are characterized by faster initiation rates
which are associated with a lower stability, especially in
solution, allowing for a successful execution of metathesis
reactions at lower temperatures (from 0 to 22 °C).
To examine the application profile of our catalysts in more
detail, we conducted the RCM reaction with diethyl allyl(2-
methylallyl)malonate (S2), which is a more demanding sub-
strate than S1. The conversion plots in Scheme 6 showed
similar tendencies in the relative performance of complexes.
We observed little difference in reactivity trends using
XIIa, Xa, and XIIc (from 72 to 74%). These results may be
explained by a stabilizing effect due to the steric hindrance of
the tert-butyl group and the presence of a strong electron-
donating group in the benzylidene moiety.19 On the other
hand, complex XIIb, with a phenyl substituent, and XIa,
containing an IMes ligand, turned out to be much less active
under such conditions (respectively 61% and 27%).
confirmed examples available in the literature.20 The third-
generation complex XIIIa proved to be a very fast initiator,
giving 87% yield for S1 and 41% for S2 just after 2 min (in
Schemes 5 and 6, respectively) with a noticeably lower over-
all activity (91% (S1) and 70% (S2)) than in the case of XIIa.
Other representative examples of RCM and CM reactions
are shown in Table 2. Although the first two transformations
presented (entries 1 and 2) were conducted at 0 °C with low
catalyst loading (1 mol %), they proceeded in good yield
within 15 min. Cyclizations of unhindered diene S3 and enyne
S4 were achieved in almost quantitative yields in less than
0.5 h. The last example of efficiency of sulfone-based cata-
lysts, shown in entry 5, demonstrates the utility in the CM
reaction even at room temperature. It is worth mentioning
that in this case P5 is the only product, as the conditions
applied in the reaction prevent self-metathesis of S5b. To
obtain a complete picture of the activity of catalyst XIIIa, we
repeated the procedure applied for other analogues. The
results received for XIIIa follow previously observed reactiv-
ity trends toward model substrates shown in Table 2 for XIIa.
It is also worth noting that the analogue XIIIa presented
higher stability in different solvents in comparison to con-
geners XIIb and XIa.
Comparing the influence of an additional ligand on the
catalytic behavior of initiator XIIIa required following the
same metathesis reactions and correlating the results with
those obtained for other complexes. This allowed us to
monitor the difference in the initiation rates, stabilities and
the overall performance of catalysts. Kinetic studies
In light of these results, we investigated the catalytic
activity toward tetrasubstituted diene S6 using the most
promising initiators: XIIa and XIIIa. (Table 3).
(19) Grela, K.; Kim, M. Eur. J. Org. Chem. 2003, 963–966.
(20) (a) Love, J. A.; Morgan, J. P.; Trnka, T. M.; Grubbs, R. H.
Angew. Chem., Int. Ed. 2002, 41, 4035–4037. (b) Sanford, M. S.; Love,
J. A.; Grubbs, R. H. Organometallics 2001, 20, 5314–5318.
We found that complex XIIa applied at low loading
(1 mol %) at 40 °C in CH2Cl2 resulted in only 2% conversion
of substrate S6 after 15 min. Even when the reaction time was

1136 Organometallics, Vol. 30, No. 5, 2011
Szadkowska et al.
Table 3. RCM of S6 using XIIa and XIIIa
4.1.1. Oxidation Reaction (3a and 3b). Water (4 mL) and
Oxone (2.60 g, 4.1 mmol) were placed in a three-necked, round-
bottomed flask, equipped with a stirrer, thermometer, and an
addition funnel with a pressure-equalization arm. The mixture
was cooled to 5 °C and vigorously stirred, while a solution of the
appropriate sulfide (2.1 mmol) in MeOH (4 mL) was placed in
the funnel and added dropwise to the stirred slurry. After
addition of the sulfide the reaction mixture was stirred at room
temperature for 2 h. Subsequently, methanol was removed on a
rotary evaporator. The remaining solution was extracted with
methylene chloride (2 ꢀ 5 mL). The combined organic layers
were dried over MgSO4, concentrated to ca. 3 mL, filtered
through a plug of silica gel, and washed with an additional 3
mL of CH2Cl2. The colorless filtrate was concentrated, and the
resulting oil or solid was dried under vacuum at room tempera-
ture to provide a corresponding sulfone (yield of 75-76%).
1-Bromo-2-(tert-butylsulfonyl)benzene (3a). Colorless crys-
a Conditions: c[S6] = 0.1 M, 15 min, 1 and 24 h.
1
tals, yield 75%. H NMR (400 MHz, CDCl3): δ 1.42 (s, 9H),
prolonged to 1 and 24 h, no change in the conversion was
noted, as used catalysts tend to decompose at elevated
temperatures. Increasing the initiator’s loading to 5 mol %
and heating the reaction mixture to 40 and 80 °C was not
helpful, as we obtained only slightly improved conversions,
from 14% to 21% for XIIa and 5% to 9% for XIIIa. These
findings forced us to conclude that although the new catalysts
(XIIa and XIIIa) present increased reaction rates at low
temperatures as compared to the second-generation Hoveyda
catalyst (II), they fail to conduct a ring closure that gives
tetrasubstituted olefins. It should be noted that the latter
transformation is problematic also for Gru-II and Hov-II
catalysts.1g Probably the approach of an increasingly bulky
substrate causes difficulties in metathesis and promotes de-
composition of active species, due to steric hindrance in the
NHC ligand and weaker stabilization of the sulfone group.
7.39-7.54 (m, 2H), 7.73-7.84 (m, 1H), 8.02-8.14 (m, 1H). 13
C
NMR (100 MHz, CDCl3): δ 24.0, 62.5, 122.9, 127.5, 134.4,
134.9, 135.1, 136.4. MS (EI; m/z (relative intensity)): 39 (19), 41
(12), 56 (26), 57 (100), 58 (30), 75 (29), 76 (27), 77 (24), 156 (29)
158 (29), 278 (67). IR (KBr): ν 3087, 3064, 2985, 2970, 2934,
2868, 2004, 1978, 1951, 1864, 1779, 1748, 1665, 1573, 1563, 1476,
1447, 1424, 1390, 1370, 1363, 1300, 1275, 1262, 1214, 1196, 1170,
1137, 1124, 1095, 1037, 1024, 977, 940, 893, 798, 777, 771, 739,
709, 656, 630, 571, 520, 480 cm-1. Anal. Calcd for C10H13SBrO2:
C, 43.33; H, 4.72; S, 11.57; Br, 28.83. Found: C, 43.52; H, 4.87; S,
11.46; Br, 28.94. Mp: 90-91 °C.
1-Bromo-2-(phenylsulfonyl)benzene (3b). Yellowish crystals,
yield 76%. 1H NMR (400 MHz, CDCl3): δ 7.36-7.47 (m, 1H),
7.48-7.56 (m, 3H), 7.57-7.63 (m, 1H), 7.64-7.73 (m, 1H),
7.89-8.02 (m, 2H), 8.35-8.47 (m, 1H). 13C NMR (100 MHz,
CDCl3): δ 121.2, 127.9, 128.6, 128.48, 131.4, 133.4, 134.6, 135.6,
139.8; MS (EI; m/z (relative intensity)): 50 (10), 51 (16), 75 (12),
76 (11), 125 (56), 153 (9), 203 (54), 205 (64), 296 (45), 298 (44).
HRMS (EI; m/z): calcd for [M]þ• (C12H9S79BrO2) 295.950 66,
found 295.950 66. IR (KBr): ν 3079, 3067, 1955, 1884, 1845,
1648, 1570, 1474, 1447, 1427, 1316, 1282, 1249, 1176, 1154, 1132,
1104, 1081, 1066, 1027, 999, 882, 839, 771, 756, 741, 711, 681,
648, 614, 584, 565, 502, 489, 449, 415 cm-1. Anal. Calcd for
C12H9SBrO2: C, 48.50; H, 3.05; S, 10.79; Br, 26.89. Found: C,
48.41; H, 3.24; S, 10.53; Br, 26.63. Mp: 116-118 °C.
3. Conclusions
In summary, we have reported the syntheses and charac-
terization of new sulfone and sulfonamide chelating active
Ru initiators. The investigation of their catalytic activity,
especially in the RCM reactions at low temperatures,
pointed out their good applicability to unhindered and
moderately hindered substrates. The analysis of the struc-
ture-catalytic performance relationship proved that these
new initiators can be tuned by changing the steric and
electronic environments of the benzylidene and NHC ligand.
It is worth highlighting that the SO2 group increases the
reactivity of the ruthenium complexes, which combined with
the good stability provided by SIPr ligands leads to the
promising stable and active catalysts XIIa and XIIIa.21 The
formal oxidation of sulfur atom from þ2 to þ6 gives rise to
new “rocket” catalysts, which are expected to find applica-
tions in metathesis science. Related ongoing research on
sulfur-containing catalysts will be reported in due course.
4.1.2. Alkylation Reaction (2-Bromo-N,N-dimethylbenzene-
sulfonamide (6)). To a suspension of K2CO3 (1.05 g, 8 mmol)
and Cs2CO3 (0.312 g, 0.96 mmol) in DMF (10 mL) was added
2-bromobenzenesulfonamide 5 (0.76 g, 3.2 mmol). After the
mixture was stirred for 30 min, iodomethane (1 g, 0.44 mL, 7.04
mmol) was added and the reaction mixture was stirred for 1 h at
room temperature. Then the mixture was poured into water
(8 mL) and extracted with diethyl ether (2 ꢀ 10 mL); the com-
bined organic phases were washed with water and brine and dried
over MgSO4. Solvent was removed in vacuo, and the crude
product was purified by column chromatography, using as an
eluent pure cyclohexane and later a cyclohexane/ethyl acetate
mixture (10/1 v/v) to give 6 as colorless crystals (0.48 g, yield
92%). 1H NMR (400 MHz, CDCl3): δ 2.76-3.03 (s, 6H),
7.28-7.59 (m, 2H), 7.65-7.85 (m, 1H), 7.99-8.17 (m, 1H). 13C
NMR (100 MHz, CDCl3): δ 37.3, 120.4, 127.5, 132.3, 133.5,
135.7, 137.8. MS (EI; m/z) (relative intensity)): 42 (23), 44 (100),
155 (50), 157 (55), 184 (13), 219 (14), 221 (18), 263 (42). IR (KBr):
ν 3087, 3028, 2915, 1848, 1806, 1496, 1994, 1958, 1925, 1874,
1836, 1732, 1646, 1574, 1565, 1473, 1448, 1424, 1344, 1268, 1257,
1171, 1159, 1127, 1100, 1053, 1039, 1023, 957, 767, 748, 701, 688,
644, 578, 535, 512, 480, 440 cm-1. Anal.Calcdfor C8H10SBrNO2:
C, 36.38; H, 3.82; S, 12.14; Br, 30.25; N, 12.14. Found: C, 36.31;
H, 3.77; S, 12.14; Br, 30.05; N, 5.31. Mp: 55-57 °C.
4. Experimental Section22
4.1. Synthesis of Ligand Precursors. Compounds 2a,b were
synthesized according to literature procedures.8a
(21) For other S-containing catalysts, see: (a) Monfette, S.; Fogg,
D. E. Organometallics 2006, 25, 1940–1944. (b) Katayama, H.; Nagao,
M.; Ozawa, F. Organometallics 2003, 22, 586–593. (c) Bieniek, M.;
€
Bujok, R.; Ste-pkowska, H.; Jacobi, A.; Hagenkotter, R.; Arlt, D.;
Jarzembska, K.; Wozniak, K.; Grela, K. J. Organomet. Chem. 2006,
ꢀ
4.1.3. Suzuki-Miyaura Cross-Coupling (4a,b and 7). A solu-
tion of potassium (vinyl)trifluoroborate (0.32 g, 2.36 mmol),
PdCl2(PPh3)2 (0.044 g, 0.065 mmol), Cs2CO3 (2.1 g, 6.45 mmol),
691, 5289–5297.
(22) For full experimental details and other information see the
Supporting Information.

Article
Organometallics, Vol. 30, No. 5, 2011 1137
and a suitable sulfone (2.15 mmol) in THF/H2O (9/1 v/v) (10 mL)
was heated at 85 °C under anargonatmosphere in a Schlenktube.
The reaction mixture was stirred at this temperature for 22 h and
then cooled to room temperature and diluted with H2O (6 mL)
followed by extraction with DCM (3 ꢀ 10 mL). The combined
organic phases were dried over MgSO4. The solvent was removed
in vacuo, and the crude product was purified by silica gel column
chromatography (using cyclohexane/ethyl acetate 10/1 to 1/1 v/v)
to obtain the corresponding styrene (70-82% yield).
1-(tert-Butylsulfonyl)-2-vinylbenzene (4a). Colorless crystals,
yield 80%. 1H NMR (500 MHz, CDCl3): δ 1.11-1.52 (s, 9H),
5.39-5.45 (dd, J = 1.1, 11 Hz, 1H), 5.66-5.73 (dd, J = 1.0, 17
Hz, 1H), 7.40-7.46 (m, 1H), 7.57-7.63 (m, 1H), 7.67-7.72 (m,
1H) 7.81-7.88 (m, 1H) 7.93-7.96 (m, 1H). 13C NMR (125
MHz, CDCl3): δ 23.8, 61.5, 118.2, 127.5, 128.1, 132.4, 133.1,
133.7, 134.9, 140.2. MS (EI; m/z (relative intensity)): 41 (17), 57
(100), 58 (5), 77 (10), 103 (7), 104 (12), 119 (8), 137 (20), 168 (45)
224 (7). IR (KBr): ν 3058, 3032, 2975, 2934, 2869, 2003, 1947,
1864, 1676, 1622, 1590, 1560, 1467, 1411, 1397, 1364, 1318, 1281,
1270, 1203, 1171, 1132, 1114, 1047, 1020, 1010, 1000, 897, 800,
776, 760, 738, 699, 649, 633, 590, 571, 556, 521, 475 cm-1. Anal.
Calcd for C12H16SO2: C, 64.25; H, 7.19; S, 14.29. Found: C,
64.06; H, 7.23; S, 14.06. C. Mp: 109-111 °C.
1-(Phenylsulfonyl)-2-vinylbenzene (4b). Yellowish crystals,
yield 82%. 1H NMR (500 MHz, CDCl3): δ 5.30-5.32 (dd,
J = 1.2, 11 Hz, 1H), 5.50-5.52 (dd, J = 1.1, 17 Hz, 1H),
7.43-7.49 (m, 5H), 7.49-7.52 (m, 1H), 7.83-7.88 (m, 3H),
8.18-8.21 (m, 1H). 13C NMR (125 MHz, CDCl3): δ 118.9,
127.6, 127.7, 128.0, 128.3, 128.9, 129.3, 133.0, 133.2, 133.7,
137.7, 138.0, 141.6. MS (EI; m/z (relative intensity)): 51 (20),
77 (43), 91 (100), 153 (11), 165 (24), 178 (23), 179 (42), 180 (12),
197 (9), 213 (8), 244 (10). IR (KBr): ν 3090, 3067, 3028, 1905,
1845, 1776, 1692, 1654, 1622, 1582, 1560, 1477, 1464, 1448, 1407,
1317, 1309, 1296, 1283, 1196, 1152, 1124, 1090, 1070, 1043, 1021,
999, 919, 883, 850, 795, 776, 760, 721, 689, 595, 575, 561, 520,
482, 434 cm-1. Anal. Calcd for C14H12SO2: C, 68.83; H, 4.95; S,
13.12. Found: C, 68.66; H, 4.88; S, 12.97. Mp: 76-78 °C.
N,N-Dimethyl-2-vinylbenzenesulfonamide (7). Yellow oil,
yield 70%. 1H NMR (500 MHz, CDCl3): δ 2.74-2.77 (s, 6H),
5.41-5.43 (dd, J = 1.2, 11 Hz, 1H), 5.66-5.70 (dd, J = 1.2,
17 Hz, 1H), 7.38-7.42 (m, 1H), 7.53-7.57 (m, 2H), 7.63-7.61
(m, 1H), 7.93-7.78 (m, 1H). 13C NMR (125 MHz, CDCl3):
δ 37.4, 118.1, 127.6, 128.4, 130.1, 132.9, 134.5, 134.7, 137.9. MS
(EI; m/z (relative intensity)): 42 (17), 44 (34), 51 (20), 77 (67), 78
(14), 91 (12), 102 (25), 103 (86), 104 (54), 119 (10), 132 (78), 146
(100), 211 (67). IR (KBr): ν 3554, 3091, 3065, 3027, 2962, 2928,
2884, 2850, 2813, 1849, 1732, 1625, 1591, 1563, 1468, 1412, 1342,
1284, 1270, 1200, 1159, 1123, 1051, 1022, 996, 955, 931, 883, 795,
772, 756, 718, 674, 595, 567, 537, 479, 458, 425 cm-1. Anal.
Calcd for C10H13SNO2: C, 56.85; H, 6.20; S, 15.18; N, 6.63.
Found: C, 56.65; H, 6.34; S, 15.29; N, 6.42.
7.42-7.53 (m, 1H), 7.61-7.72 (m, 2H), 7.83-7.88 (m, 1H),
18.91 (s, 1H). 13C NMR (150 MHz, CDCl3): δ 17.9, 19.0, 20.3,
21.2, 23.0, 62.9, 64.5, 120.2, 126.4, 129.4, 130.1, 130.6, 132.3,
135.8, 137.7, 138.3, 138.7, 139.5, 141.4, 147.3, 153.8, 209.0,
271.1. MS (FD/FI; m/z): calcd for [M]þ 688.7380, found
688.7357. IR (KBr): ν 3469, 3055, 2953, 2918, 1856, 2734,
1944, 1735, 1607, 1578, 1557, 1481, 1419, 1398, 1381, 1267,
1188, 1133, 1114, 1098, 1062, 1035, 917, 884, 852, 795, 777, 755,
713, 691, 633, 579, 519, 489, 467, 424 cm-1. Anal. Calcd for
C32H40Cl2O2N2RuS: C, 55.81; H, 5.85; N, 4.07; S, 4.66; Cl,
10.30. Found: C, 55.62; H, 5.79; N, 4.21; S, 4.93; Cl, 10.58.
4.2.2. Synthesis of Catalyst XIa. A Schlenk tube equipped
with a stirring bar was charged with a ruthenium catalyst (Ind
IMes; 0.34 g, 0.5 mmol) and CuCl (0.06 g, 0.6 mmol). The tube
was flushed with argon and charged with anhydrous toluene (15
mL). The corresponding styrene 4a (0.55 mmol) in anhydrous
toluene (10 mL) was added. The resulting solution was stirred at
85 °C for 1 h. After this, all manipulations could be done without
the protective atmosphere of argon. The resulting mixture was
concentrated in vacuo, the residue was dissolved in AcOEt, and
the solution was passed through a Pasteur pipet containing a
small amount of cotton and evaporated to dryness. The crude
product was purified by column chromatography (using cyclo-
hexane/ethyl acetate 10/1 to 1/1 v/v). After evaporation of
solvents, the resulting green microcrystalline solid was collected
and washed a few times with AcOEt and cold n-pentane (0.1 g,
0.146 mmol, yield 30%).
1
XIa: green microcrystalline solid, yield 30%. H NMR (600
MHz, CDCl3): δ 0.85-1.36 (m, 9H), 2.03-2.46 (m, 18H),
4.06-4.09 (m, 2H), 6.95-7.02 (m, 3H), 7.05-7.15 (m, 2H),
7.45-7.50 (m, 1H), 7.61-7.71 (m, 1H), 7.80-7.88 (m, 1H),
19.04 (s, 1H). 13C NMR (150 MHz, CDCl3): δ 14.6, 17.7, 18.9,
22.6, 23.3, 23.5, 33.8, 63.1, 64.9, 120.2, 122.3, 124.2, 125.1, 127.2,
128.8, 129.5, 133.1, 133.4, 134.1, 134.7; 136.0, 137.5, 138.0, 139.1,
153.5, 171.7, 298.4. MS (FD/FI; m/z): calcd for [M]þ 686.7122,
found 686.7104. IR (KBr): ν 3444, 3161, 3136, 2917, 2856, 2735,
1936, 1734, 1691, 1608, 1578, 1557, 1484, 1463, 1398, 1341, 1315,
1280, 1235, 1191, 1164, 1132, 1098, 1077, 1062, 1036, 973, 962, 923,
884, 862, 795, 778, 743, 713, 692, 633, 589, 572, 519, 487, 429 cm-1
.
Anal. Calcd for C32H38Cl2O2N2RuS: C, 55.97; H, 5.58; N, 4.08; S,
4.67; Cl, 10.33. Found: C, 56.12; H, 5.73; N, 4.21; S, 4.84; Cl, 10.58.
4.2.3. General Synthesis of Catalysts XIIa-c. A Schlenk tube
equipped with a stirring bar was charged with a ruthenium
complex (SIPr Gru; 0.14 g, 0.15 mmol) and CuCl (0.016 g, 0.165
mmol). The tube was flushed with argon and charged with
anhydrous CH2Cl2 (4.5 mL). The appropriate styrene (0.18
mmol) in anhydrous CH2Cl2 (3 mL) was added, and the result-
ing mixture was stirred at 40 °C for 5 min. After this time, TLC
indicated a complete conversion of the substrate. The resulting
mixture was concentrated in vacuo, the residue was dissolved in
AcOEt, and the solution was passed through a Pasteur pipet
containing a small amount of cotton and evaporated to dryness.
The crude product was purified by column chromatography
(using cyclohexane/ethyl acetate 20/1 to 1/1 v/v). After evapora-
tion of solvents, the resulting green microcrystalline solid was
collected and washed a few times with AcOEt and with cold n-
heptane (51-57% yield).
4.2. General Syntheses of Catalysts. 4.2.1. Synthesis of
Catalyst Xa. A Schlenk tube equipped with a stirring bar was
charged with a ruthenium complex (Ind SIMes; 0.34 g, 0.5
mmol) and CuCl (0.055 g, 0.55 mmol). The tube was flushed
with argon and charged with anhydrous toluene (15 mL).
Styrene 4a (0.135 g, 0.6 mmol) in anhydrous toluene (10 mL)
was added, and the resulting mixture was stirred at 85 °C for 1 h.
After this time, TLC indicated a complete conversion of the
substrate. The resulting mixture was concentrated in vacuo, the
residue was dissolved in AcOEt, and the solution was passed
through a Pasteur pipet containing a small amount of cotton
and evaporated to dryness. The crude product was purified by
column chromatography (using cyclohexane/ethyl acetate 10/1
to 1/1 v/v). After evaporation of solvents, the resulting solid was
collected and washed a few times with AcOEt and with cold
n-pentane (0.105 g, 0.15 mmol, yield 30%).
XIIa: light green microcrystalline solid, yield 57%. 1H NMR
(600 MHz, CDCl3): δ 1.00 (s, 9H), 1.31-1.50 (m, 14H),
1.56-1.63 (m, 2H), 3.68-4.20 (m, 4H), 7.30-7.39 (m, 2H),
7.40-7.45 (m, 2H), 7.50-7.72 (m, 4H), 7.68-8.00 (m, 2H),
18.66 (s, 1H). 13C NMR (150 MHz, CDCl3): δ 13.9, 21.5, 23.2,
23.6, 23.7, 23.8, 24.1, 24.7, 25.2, 26.7, 27.4, 28.5, 29.9, 34.9, 61.7,
118.2, 122.4, 124.1, 124.5, 125.0, 127.2, 127.5, 128.1, 128.7,
129.9, 130.4, 132.3, 133.1, 133.3, 133.5, 133.7, 134.9, 138.1,
140.2, 148.7, 152.7, 210.7, 295.9. MS (FD/FI; m/z): calcd for
[M]þ 772.8943, found 772.8930. IR (KBr): ν 3514, 3062, 2966,
2927, 2867, 1944, 1701, 1629, 1586, 1558, 1464, 1445, 1408, 1396,
1364, 1344, 1325, 1282, 1263, 1233, 1192, 1134, 1100, 1079, 1058,
1023, 994, 933, 884, 804, 758, 738, 726, 713, 691, 633, 590, 580,
1
Xa: green microcrystalline solid, yield 30%. H NMR (600
MHz, CDCl3): δ 1.03 (s, 6H), 1.23 (s, 3H), 2.21-2.57 (m, 18H),
4.75-4.25 (m, 4H), 6.91-6.95 (m, 1H), 7.00-7.21 (m, 3H),

1138 Organometallics, Vol. 30, No. 5, 2011
Szadkowska et al.
567, 551, 519, 489, 457 cm-1. Anal. Calcd for C38H52Cl2O2N2-
RuS: C, 59.05; H, 6.78; N, 3.62; S, 4.15; Cl, 9.17. Found: C,
59.22; H, 6.71; N, 3.56; S, 4.03; Cl, 9.28.
was added to a NMR tube. The tube was stirred for a few
seconds (the reaction time started at this point) and introduced
to the spectrometer (locked and shimmed), and conversions
were measured by 1H NMR.
XIIb: dark green microcrystalline solid, yield 51%. 1H NMR
(600 MHz, CDCl3): δ 1.18-1.50 (m, 22H), 2.26 (s, 2H),
3.66-3.78 (m, 3H), 4.08-4.16 (m, 3H), 7.28-7.39 (m, 4H),
7.40-7.50 (m, 2H), 7.52-7.58 (m, 2H), 7.60-7.70 (m, 1H),
7.75-7.95 (m, 4H), 8.15-8.30 (m, 1H), 18.81 (s, 1H). 13C NMR
(150 MHz, CDCl3): δ 14.6, 21.3, 24.3, 25.7, 26.5, 28.7, 60.4,
119.0, 124.8, 127.0, 127.6, 128.0, 128.3, 128.4, 128.5, 128.8,
128.9, 129.2, 129.4, 129.7, 131.9, 133.0, 133.2, 133.3, 133.5,
133.9, 136.6, 137.8, 140.0, 141.9, 148.6, 170.6, 210.3, 298.0.
MS (FD/FI; m/z): calcd for [M]þ 792.3456, found 792.3440.
IR (KBr): ν 3436, 3062, 2025, 2964, 2926, 2867, 1945, 1697, 1631,
1585, 1557, 1465, 1446, 1408, 1386, 1364, 1323, 1295, 1264, 1234,
1179, 1147, 1120, 1089, 1059, 1024, 998, 931, 885, 852, 804, 776,
758, 723, 688, 633, 597, 571, 459 cm-1. Anal. Calcd for
C40H48Cl2O2N2RuS: C, 60.59; H, 6.10; N, 3.53; S, 4.04; Cl,
8.94. Found: C, 60.48; H, 5.97; N, 3.58; S, 4.27; Cl, 8.75.
XIIc: green microcrystalline solid, yield 52%. 1H NMR (600
MHz, CDCl3): δ 0.84-0.89 (m, 2H), 1.05-1.50 (m, 21H), 2.43
(s, 6H), 2.72-2.78 (m, 1H), 3.50-3.80 (m, 2H), 4.11 (s, 3H),
7.30-7.40 (m, 6H), 7.47-7.55 (m, 2H), 7.60-7.65 (m, 3H),
18.64 (s, 1H). 13C NMR (150 MHz, CDCl3): δ 14.1, 22.6, 23.7,
24.0, 26.2, 26.5, 28.8, 31.6, 37.6, 124.3, 124.7, 127.9, 128.2, 129.6,
130.0, 132.8, 133.5, 148.8, 149.2, 152.3, 152.4, 210.7, 295.7. MS
(FD/FI; m/z): calcd for [M]þ 759.8521, found 759.8537. IR
(KBr): ν 3501, 3063, 2964, 2927, 2867, 1948, 1731, 1695, 1629,
1586, 1464, 1444, 1409, 1387, 1363, 1326, 1297, 1264, 1234, 1179,
1150, 1114, 1057, 1049, 994, 955, 934, 884, 804, 758, 724, 701,
674, 645, 621, 600, 582, 570, 551, 535, 477, 458 cm-1. Anal.
Calcd for C36H49Cl2O2N2RuS: C, 56.91; H, 6.50; N, 5.53; S,
4.22; Cl, 9.33. Found: C, 56.72; H, 6.73; N, 5.58; S, 4.08; Cl, 9.61.
4.2.4. Synthesis of Catalyst XIIIa. A Schlenk tube equipped
with a stirring bar was charged with a ruthenium complex (XIIa;
0.124 g, 0.16 mmol) and 3-bromopyridine (0.390 mL, 0.632 g,
4 mmol). The resulting mixture was stirred at 22 °C for 10 min.
After this time, TLC indicated complete conversion of XIIIa.
The resulting mixture was concentrated in vacuo. The green
residue was dissolved in a minimum amount of dichloromethane
and washed with cold n-heptane (5 mL). The light green pre-
cipitate was filtered, washed with n-heptane (2ꢀ5 mL). and
dried under vacuum to afford light green microcrystalline solid
XIIIa (0.078 g, 0.084 mmol, 52% yield).
4.3.2. Time-Conversion Studies. GC Conversions. At 0 °C.
Cyclization of substrates: S1 and S2 were used as a test to
compare the activity of catalysts in CH2Cl2 at 0 °C. Typically,
1 mol % of the catalyst (0.008 mmol) was added to a solution of
substrate (0.8 mmol) and an internal standard in 8 mL of CH2Cl2
at 0 °C. The reaction was run at 0 °C under argon, and samples
were taken after 5, 10, and 15 min and analyzed by TLC and GC.
At 22 °C (RCM and Enyne Cycloisomerization). Cyclization of
substrates: S3 and S4 were used as a test to compare the activity
of catalysts in CH2Cl2 at 22 °C. Typically, 1 mol % of the
catalyst (0.008 mmol) was added to a solution of substrate (0.8
mmol) and an internal standard in 8 mL of CH2Cl2 at 22 °C. The
reaction was run at 22 °C under argon, and samples were taken
after 5, 10, and 15 min and analyzed by TLC and GC.
At 22 °C (CM). Cross-metathesis of S5a and S5b was used as a
test to compare the activity of catalysts in CH2Cl2 at 22 °C.
Catalyst (2 mol %, 0.012 mmol) was added to a solution of
substrates (0.6 mmol for S5b and 1.2 mmol for S5a) in 3 mL of
CH2Cl2 at 22 °C. The reaction was run at 22 °C under argon, and
samples were taken after 30 min and analyzed by TLC and 1H
NMR.
At 40 °C. Cyclization of diethyl allyl(2-methylallyl)malonate
(S6) was used as a test to compare the activity of catalysts in
CH2Cl2 at 40 °C. Catalyst (1 mol %, 0.008 mmol) was added to a
solution of substrate (0.8 mmol) and an internal standard in
8 mL of CH2Cl2 at 40 °C. The reaction was run at 40 °C under
argon, and samples were taken after 15 min and 1 and 24 h and
analyzed by GC.
At 40 °C. Cyclization of diethyl allyl(2-methylallyl)malonate
(S6) was used as a test to compare the activity of catalysts in
CH2Cl2 at 40 °C. Catalyst (5 mol %, 0.02 mmol) was added to a
solution of substrate (0.4 mmol) and an internal standard in
4 mL of CH2Cl2 at 40 °C. The reaction was run at 40 °C under
argon, and samples were taken after 15 min and 1 and 24 h and
analyzed by GC.
At 80 °C. Cyclization of diethyl allyl(2-methylallyl)malonate
(S6) was used as a test to compare the activity of catalysts in
toluene at 80 °C. Catalyst (5 mol %, 0.02 mmol) was added to a
solution of substrate (0.4 mmol) and an internal standard in
4 mL of toluene at 80 °C. The reaction was run at 80 °C under
argon, and samples were taken after 15 min and 1 and 24 h and
analyzed by GC.
XIIIa: light green microcrystalline solid, yield 52%. 1H NMR
(600 MHz, CDCl3): δ 1.01 (s, 9H), 1.15-1.30 (m, 18H),
1.32-1.34 (m, 2H), 1.36-1.38 (m, 2H), 7.15-7.25 (m, 2H),
7.28-7.40 (m, 5H), 7.41-7.45 (m, 2H), 7.57-7.63 (m, 2H),
7.78-7.85 (m, 3H), 18.70 (s, 1H). 13C NMR (150 MHz, CDCl3):
δ 14.4, 23.2, 23.7, 25.8, 26.2, 28.4, 28.8, 63.1, 122.1, 124.6, 127.1,
129.2, 133.1, 134.8, 138.6, 148.3, 149.2, 151.3, 152.6, 210.7, 296.3.
MS (FD/FI; m/z): calcd for [M]þ 930.6458, found 930.6460. IR
(KBr): ν 3436, 3062, 2959, 2925, 2865, 1935, 1739, 1667, 1628,
1588, 1556, 1463, 1440, 1413, 1390, 1362, 1349, 1325, 1302, 1282,
1264, 1247, 1230, 1194, 1170, 1157, 1134, 1099, 1059, 1045, 1028,
1006, 998, 981, 962, 929, 905, 884, 869, 827, 803, 794, 759, 712,
698, 634, 579, 572, 555, 517, 497, 460, 417 cm-1. Anal. Calcd for
C43H56Cl2O2N3RuBrS: C, 55.48; H, 6.06; N, 4.51; S, 3.44; Cl,
7.62. Found: C, 55.32; H, 6.19; N, 4.71; S, 3.31; Cl, 7.78.
4.3. General Procedure for Preparative RCM and CM Reac-
tions using Xa, XIa, XIIa-c, and XIIIa. 4.3.1. Time-Conver-
sion Studies. All catalytic reactions were prepared under an inert
atmosphere of argon gas. All reactions were run in NMR tubes
at 22 °C at a 0.1 M substrate/concentration, and the progress of
the reaction was followed by 1H NMR spectroscopy. Substrates:
S1 and S2 (0.08 mmol, 19.2 and 20.3 mg, respectively) were
dissolved in CD2Cl2 (0.7 mL) and then transferred with a syringe
to the respective NMR tube. To obtain the required catalyst
amount, a solution of suitable ruthenium initiator (0.01 mol, 6
mg) was dissolved in 1 mLof CD2Cl2 and 100 μL of this solution
Acknowledgment. This work was supported by Grant
No. N204157636, which was provided by the Polish Min-
istry of Science and Higher Education. K.G. and K.W.
thank the Foundation for Polish Science for “Mistrz”
professorships. This contribution was also established by
financial support of the Foundation for Polish Science
(A.S. acknowledges the “START”-2010 grant for young
researchers). Single-crystal X-ray measurements were ac-
complished at the Structural Research Lab (SRL) of the
Chemistry Department, Warsaw University, Warsaw, Po-
land. The SRL has been established with financial support
from the European Regional Development Found in the
Sectoral Operational Programme “Improvement of the
Competitiveness of Enterprises, years 2004-2006” Project
No. WKP_ 1/1.4.3./1/2004/72/72/165/2005/U. We wish to
thank Mr. Jan Klajn for technical assistance.
Supporting Information Available: Figures, tables, text, and
CIF files giving 1H NMR and 13C NMR spectra of all new
compounds and X-ray crystallographic data. This material is
available free of charge via the Internet at http://pubs.acs.org.