Ruthenium Olefin Metathesis Initiators Bearing Chelating Sulfoxide

Apr 10, 2009 - The presence of a N→Ru or O→Ru chelate favors the “sleeping” precatalyst over its metathesis active coordinatively unsaturated ...
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Organometallics 2009, 28, 2693–2700

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Ruthenium Olefin Metathesis Initiators Bearing Chelating Sulfoxide Ligands Anna Szadkowska,† Anna Makal,‡ Krzysztof Woz´niak,‡ Renat Kadyrov,§ and Karol Grela*,† Institute of Organic Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland, Department of Chemistry, Warsaw UniVersity, Pasteura 1, 02-093 Warsaw, Poland, and EVonik Degussa GmbH, 097-12a Rodenbacher Chaussee 4, 63457 Hanau-Wolfgang, Germany ReceiVed December 14, 2008

New ruthenium olefin metathesis initiators bearing sulfoxide moieties are described. The complexes were synthesized by the reaction of indenylidene ruthenium complexes Ind-II and Ind-II′ with different (2-vinyl)phenyl sulfoxides. These compounds show no catalytic activity at room temperature, but exhibit increased activity at elevated temperature. Preliminary studies on the influence of electronic and steric factors on the catalytic activity are presented. Introduction Modern olefin metathesis catalysts have evolved toward increasing stability and activity.1 Organic chemists were provided with well-defined catalysts, which show high activity and fast initiation in a range of metathesis reactions (Figure 1).2 Modern Ru catalysts promote metathesis not only in the neutral organic solvents traditionally used for metathesis (dichloromethane and toluene) but also in protic organic solvents, water,3 and room-temperature ionic liquids.4 However, in some applications of olefin metathesis it could be beneficial if the catalyst initiation is delayed. One of such cases is ring-opening metathesis polymerization.5-7 In some industrial set-ups of the ROMP reaction it is required that a mixture of a monomer and an initiator is processed (or stored) before the metathesis process occurs.8 Ruthenium catalysts (shown in Figure 1) are relatively fast initiators. Therefore several precatalysts of reduced initiation speed have been

* Corresponding author. Phone: +48-22-343-2106. Fax: +48-22-63266-81. E-mail: [email protected]. † Polish Academy of Science. ‡ Warsaw University. § Evonik Degussa GmbH. (1) The Nobel Prize in Chemistry for 2005, jointly awarded to Yves Chauvin, Robert H. Grubbs, and Richard R Schrock for the development of the metathesis method in organic synthesis. For more reading, see: http:// nobelprize.org/nobel_prizes/chemistry/laureates/2005/chemadv05.pdf. (2) For selected reviews on olefin metathesis, see: (a) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18. (b) Grubbs, R. H. Handbook of Metathesis; Wiley-VCH: Weinheim, Germany, 2003. (c) Connon, S. J.; Blechert, S. Angew.Chem., Int. Ed. 2003, 42, 1900. (d) Astruc, D. New J. Chem. 2005, 29, 42. (3) (a) Burtscher, D.; Grela, K. Angew.Chem., Int. Ed. 2008, 121, 450. (b) Gułajski, Ł.; Michrowska, A.; Naroz˙nik, J.; Kaczmarska, Z.; Rupnicki, L.; Grela, K. ChemSusChem 2008, 1, 103. (4) S´ledz´, P.; Mauduit, M.; Grela, K. Chem. Soc. ReV. 2008, 37, 2433. (5) Buchmeiser, M. R. Chem. ReV. 2000, 100, 1565. (6) Dall’Asta, G.; Motroni, G. Eur. Polym. J. 1971, 7, 707. (7) Askar, J. J. Appl. Polym. Sci. 1993, 47, 289. (8) For some industrial applications of ruthenium catalysts in ROMP olefin metathesis (especially RIM process), see: (a) Mol, J. C. J. Mol. Catal. A 2004, 213, 39. (b) Ring Opening Metathesis Polymerisation and Related Chemistry; Khosravi, E.; Szyman´ska-Buzar, T.; Eds.; Kluwer Academic Publishers: Dordrecht, 2002; p 105. (c) http://www.telene.com.

developed.9-12 One of the few10c,e-g successful approaches to control the initiation speed of such Ru precatalysts is based on tethering a donor ligand (L) to the ruthenium center via the alkylidene group. The presence of a NfRu or OfRu chelate favors the “sleeping” precatalyst over its metathesis active coordinatively unsaturated form (Figure 2).10e,11-15 However, after the initiation event (controlled by temperature, light, or a chemical agent) and the first catalytic turnover, the donor will no longer be tethered and catalysis should proceed quickly. This switch in catalyst structure from chelated to nonchelated one makes this strategy attractive for fine-tuning of the initiation speed.10 (9) Usually, catalysts that are inert to a given olefinic substrate at room or slightly above room temperature are called “latent” or “dormant” initiators. Since the initiation rate depends not only on the catalyst but also on monomer structure, solvent, and temperature, these terms should be used with a great care. (10) (a) Denk, K.; Fridgen, J.; Herrmann, W. A. AdV. Synth. Catal. 2002, 344, 666. (b) Jordaan, M.; Vosloo, H. C. M. AdV. Synth. Catal. 2007, 349, 184. (c) De Clercq, B.; Verpoort, F. AdV. Synth. Catal. 2002, 344, 639. (d) Chang, S.; Jones, L., II; Wang, C.; Henling, L.; Grubbs, R. H. Organometallics 1998, 17, 3460. (e) van der Schaaf, P.; Kolly, R.; Kirner, H. J.; Rime, F.; Muhlebach, A.; Hafner, A. J. Organomet. Chem. 2000, 606, 65. (f) Slugovc, C.; Burtscher, D.; Mereiter, K.; Stelzer, F. Organometallics 2005, 24, 2255. (g) Burtscher, D.; Perner, B.; Mereiter, K.; Slugovc, C. J. Organomet. Chem. 2006, 691, 5423. (11) Szadkowska, A.; Grela, K. Curr. Org. Chem. 2008, 12, 1631. (12) Ung, T.; Hejl, A.; Grubbs, R. H.; Schrodi, Y. Organometallics 2004, 23, 5399. (13) (a) Barbasiewicz, M.; Szadkowska, A.; Bujok, R.; Grela, K. Organometallics 2006, 25, 3599. (b) Gstrein, X.; Burtscher, D.; Szadkowska, A.; Barbasiewicz, M.; Stelzer, F.; Grela, K.; Slugovc, C. J. Polym Sci. Part A: Polym. Chem. 2007, 45, 3494. (c) Hejl, A.; Day, M. W.; Grubbs, R. H. Organometallics 2006, 25, 6149. (d) Slugovc, C.; Perner, B.; Stelzer, F.; Mereiter, K. Organometallics 2004, 23, 3622. (e) Gawin, R.; Makal, A.; Woz´niak, K.; Mauduit, M.; Grela, K. Angew. Chem., Int. Ed. 2007, 46, 7206. (14) Gułajski, Ł.; Michrowska, A.; Bujok, R.; Grela, K. J. Mol. Catal. A 2006, 254, 118. (15) (a) Kadyrov, R.; Rosiak, A.; Tarabocchia, J.; Szadkowska, A.; Bieniek, M.; Grela, K. New Concepts in Designing Ruthenium Based Second Generation Olefin Metathesis Catalysts and their Application. In Catalysis of Organic Reactions: Twenty-second Conference; Prunier, M. L., Ed.;Chemical Industries Series, Vol. 123; CRC Press, 2008; p 568. (b) Grela, K.; Szadkowska, A.; Barbasiewicz, M.; Kadyrov, R. Neuartige schwefelhaltige Metathese Katalysatoren. (Degussa AG) DE Patent Application 102007020694.3, 2007. (c) Ben-Asuly, A.; Tzur, E.; Diesendruck, C. E.; Sigalov, M.; Goldberg, I.; Lemcoff, N. G. Organometallics 2008, 27, 811. (d) Kost, T.; Sigalov, M.; Goldberg, I.; Ben-Asuly, A.; Lemcoff, N. G. J. Organomet. Chem. 2008, 693, 2200.

10.1021/om801183g CCC: $40.75  2009 American Chemical Society Publication on Web 04/10/2009

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Figure 1. Selected catalysts for olefin metathesis.

Figure 2. Some ruthenium catalysts bearing chelating alkylidene ligands.

The influence of a NfRu or OfRu chelation on the catalytic activity was studied previously in detail.11-14,16,17 Recently, the new class of sulfur-containing Ru catalysts VII-VIII has been disclosed independently by Lemcoff and us.10e,15,18 Although VI-VIII have very low activity at room temperature, these initiators possess extremely good stability and can potentially be useful in high-temperature applications. In the course of previous works,15a it became apparent for us that the sulfur-contained Ru initiators can offer a great deal (16) (a) Grela, K.; Harutyunyan, S.; Michrowska, A. Angew. Chem., Int. Ed. 2002, 41, 4038. (b) Michrowska, A.; Bujok, R.; Harutyunyan, S.; Sashuk, V.; Dolgonos, G.; Grela, K. J. Am. Chem. Soc. 2004, 126, 9318. (c) Barbasiewicz, M.; Szadkowska, A.; Grela, K. Chem.-Eur. J. 2008, 14, 9337. (17) (a) Wakamatsu, H.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 794. (b) Wakamatsu, H.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 2403. (c) Bieniek, M.; Bujok, R.; Cabaj, M.; Lugan, N.; Lavigne, G.; Arlt, D.; Grela, K. J. Am. Chem. Soc. 2006, 128, 13652. (d) Bieniek, M.; Bujok, R.; Ste¸pkowska, H.; Jacobi, A.; Hagenko¨tter, R.; Arlt, D.; Jarzembska, K.; Woz´niak, K.; Grela, K. J. Organomet. Chem. 2006, 691, 5289. (e) Michrowska, A.; Gułajski, Ł.; Kaczmarska, Z.; Mennecke, K.; Kirschning, A.; Grela, K. Green Chem. 2006, 8, 685. For an overview on HoveydaGrubbs catalysts, see: (f) Michrowska, A.; Grela, K. Pure Appl. Chem. 2008, 80, 31. (18) For other S-containing catalysts, see: (a) Monfette, S.; Fogg, D. E. Organometallics 2006, 25, 1940. (b) Katayama, H.; Nagao, M.; Ozawa, F. Organometallics 2003, 22, 586.

of tunability and can find various applications in olefin metathesis. In the present study we focused on a new class of sulfoxidebearing ruthenium complexes and examined their applicability as initiators in olefin metathesis.

Results and Discussion The commercially available 2-bromothiophenol 1 was transformed into sulfoxide-bearing ligand precursor 4a, using oxidation of sulfide 2a with Oxone19 and Suzuki-Miyaura crosscoupling with potassium (vinyl)trifluoroborate as key steps (Scheme 1).20 The final exchange reaction was performed in the presence of CuCl, in toluene at 80 °C, leading to formation of IXa as green crystals in 72% yield. Complex IXa was found to be perfectly stable in air and was fully characterized by spectral techniques and elemental analysis. Next, three model diene and enyne ring-closing metathesis (RCM) reactions were chosen as the first activity assay of the sulfoxide catalyst (Schemes 2-4). The course of each reaction was monitored by GC with dodecane or tetradecane as an internal standard, measuring the increase in the amount of (19) McCarthy, J. R.; Matthews, D. P.; Paolini, J. P. Organic Syntheses; Wiley: New York, 1998; Collect. Vol. 9; p 446. (20) Molander, G. A.; Brown, A. R. J. Org. Chem. 2006, 71, 9681.

Ruthenium Olefin Metathesis Initiators

Organometallics, Vol. 28, No. 9, 2009 2695 Scheme 1. Synthesis of Ru Initiator IXa

Scheme 2. RCM of Diene S1a

a

Conditions c[S1] ) 0.02 M, 1 mol % of IXa, CH2Cl2, 24 °C, 6 h.

Scheme 3. RCM of Diene S2a

a

Conditions c[S2] ) 0.02 M, 1 mol % of IXa, toluene, 80 °C, 1 h.

Scheme 4. RCM of Enyne S3a

a

Conditions c[S3] ) 0.02 M, 1 mol % of IXa, CH2Cl2, 24 °C, 6 h.

product with time. Catalyst IXa showed good activity in these model transformations, albeit lower than that of commercially available catalysts. For example, Gru-II is much more active in metathesis of diene S1 under similar conditions, affording almost the same conversion (86%) just after 1 h. In the case of metathesis of S2, the use of Gru-II led to the same conversion at lower temperature (30 °C). Next, we attempted to investigate the influence of the nature of the NHC ligand on the catalytic activity of the resulting ruthenium complexes (Figure 3). Starting from the same ligand precursor (4a in Scheme 1) and commercially available IndII′ (CatMetium IMesPCy) the IMes-containing Xa was obtained in 60% yield, as green, air-stable crystals. In accordance with the results reported for other IMes-bearing precatalysts,21 this complex was found to be slightly less productive than it is SIMes analogue IXa. For example, Xa failed completely in RCM of diene S1 (1 mol % of Xa, 48 h, room temperature), whereas cycloisomerization of S3 gave only 47% conversion after 6 h. In the formation of a trisubstituted double bond in RCM reaction of S2, catalyst Xa exhibited only 18% of conversion after 1 h (Table 1). Next, we attempted to study the influence of the substituent R attached to the sulfur atom (Figure 3). The ruthenium (21) Clavier, H.; Nolan, S. P. Chem.-Eur. J. 2007, 13, 8029.

complexes Xa-g and their precursors (Table 2) were prepared according to the general method shown in Scheme 1 and were found to possess very good air, moisture, and thermal stability. All complexes were characterized by 1H and 13C NMR spectroscopy and elemental analysis. As illustrated in Figures 4-6, the catalysts Xb, Xc, and Xg containing more bulky substituents R were more active in model metathesis reaction than less bulky Xe and Xd.15c,15d To provide a more comprehensive picture of the structure-reactivity relationship of this class of initiators, we prepared complex Xf, which showed even higher catalytic activity then Xg and Xc. To check if this increase of activity was more electronic (EWG p-nitrophenyl substituent) or steric in nature, we prepared also Xg, containing a phenyl substituent. Interestingly, this complex turned out to be only a bit less active than Xf. Surprisingly, even the most active sulfoxide’s representative, catalyst Xf, was still inactive in ring-closing metathesis of S1 at room temperature, but at elevated temperature (40 and 80 °C) initialized faster than Xa (Figures 4-6). On the basis of this observation, we suppose that steric effects seem to play a decisive role in increasing the catalytic activity of sulfoxide-bearing complexes. Having established the application profile of the sulfoxide catalysts in the formation of di- and trisubstituted C-C double bonds, we focused our efforts on the most demanding case, the formation of the tetrasubstituted carbon-carbon bonds (Scheme 5). It is believed that di(methylallyl)malonate (S4) is a very challenging model substrate for ruthenium catalysts, giving with Gru-II and Hov-II only 17% and 6% yield, respectively (5 mol %, CH2Cl2, 30 °C, 96 h).16a Catalyst GruII′, applied at higher temperature, was reported to give only

Figure 3. IMes-bearing Ru initiators Xa-g with different R substituents.

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Table 1. Catalytic Activity of SIMes and IMes Ru Initiators (VI, VII, IXa, and Xa)a

a Conditions: c ) 0.02 M, 5 mol % of VI or VII, toluene, 80 °C, 24 h, c ) 0.02 M, 1 mol % of IXa or Xa, CH2Cl2, 24 °C, 6 h. bCatalytic activity measured after 1 h in toluene, 80 °C.

Table 2. Preparation of Ru Initiators Xa-gg a b c d e f g

R

2

3

4

X

i-Pr Cy t-Bu Bn Me p-NO2C6H4 Ph

96% 53%a 58%b 94%c 92%d 84%e 65%f

78% 75% 69% 72% 62% 68% 73%

70% 70% 70% 69% 67% 74% 71%

60% 57% 57% 57% 33% 60% 58%

CyBr, KF/CsF, DMF, reflux. b t-BuOH, H2SO4/H2O, -10 °C f RT. BnCl, K2CO3/Cs2CO3, DMF, RT. d MeI, K2CO3/Cs2CO3, DMF, RT. e p-NO2C6H4F, K2CO3, EtOH, 70 °C. f C6H5I, CuI, sodium tert-butoxide, neocuproine, toluene, reflux. g If not stated otherwise, conditions shown in Scheme1 were used. a

c

Figure 4. Catalytic activity of IMes Ru initiators in RCM of S1. Conditions: 1 mol % catalyst, 40 °C, CH2Cl2, 6 h.

47% of the product (5 mol %, toluene, 80 °C, 24 h, GC yield).16b Therefore, we selected this reaction as a trial in our study. We found that under conditions typically used for this reaction,16a even the most reactive sulfoxide initiator, Xf, failed to form P4. Interestingly, while being of low activity at room temperature, this complex showed a reasonable level of activity at elevated temperatures. It was found that at 110 °C in toluene complex Xf effected the RCM of substrate S4 in a conversion similar (40%) to Gru-II (32%) (1 mol % of each catalyst, 110 °C, 20 h). The solid state structures of complexes Xc, Xd, and Xf were determined by X-ray crystallography (Figures 7, 8 and 9). Solid state structures show that the ruthenium atom is coordinated to sulfur atom, not to the sulfoxide oxygen atom. Unlike the sulfide

Figure 5. Catalytic activity of IMes Ru initiators in RCM of S2. Conditions: 5 mol % catalyst, 80 °C, toluene, 6 h.

Figure 6. Catalytic activity of IMes Ru initiators in enyne metathesis of S3. Conditions: 5 mol % catalyst, 40 °C, CH2Cl2, 4 h. Scheme 5. RCM of S4a

a

Conditions: c[S4] ) 0.02 M, 1 mol % Xf, toluene, 110 °C, 20 h.

complexes VI-VIII described by Lemcoff and us, the sulfoxide initiators possess trans-dichloro geometry and do not show a tendency for trans f cis isomerization.15

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Organometallics, Vol. 28, No. 9, 2009 2697

Figure 7. Solid state structure of Xc with thermal ellipsoids at 50% probability. Hydrogen atoms were omitted for clarity.

Figure 8. Solid state structure of Xd with thermal ellipsoids at 50% probability. Hydrogen atoms were omitted for clarity.

Figures 7, 8, and 9 present ORTEP representations of the discussed catalysts. Structures of Xc, Xd, and Xf show general similarity and follow the geometry of the parent Hoveyda catalyst. Table 3 gives detailed values of selected geometrical parameters. The structural differences between the most and the least active compound from the series may be analyzed in terms of Ru coordination, the position of the NHC carbene with respect to the benzylidene moiety, and the geometry of the sulfur environment. Figure 10 illustrates the more important similarities and differences by superposition of the discussed structures. Comparing of X-ray Structures of Xd and Xf. In terms of ruthenium coordination geometry, the Xd and Xf structures show great similarity. The most significant differences are the sulfur-ruthenium distance, which is longer by 0.02 Å in the case of Xd, and the Cl-Ru-Cl angle, which is wider by 2°. Interesting differences appear in the relative orientation of the main substituents. In Xf the benzylidene moiety is nearly coplanar with the imidazole ring (C22-Ru1-S1-C28 torsion angle being about -2°), while in Xd it is slanted (respective torsion -14°). Although there is no significant difference in

the Ru1-C22 bond length, the difference in orientation of the benzylidene moiety may influence the activity of the catalyst. Additionally the C4-C9 ring in Xf is located exactly above the benzylidene, and both Mes substituents are bent with respect to the imidazole plane, as the N1-C4 and N2-C13 bonds are not coplanar with the imidazole. The C13-C21 Mes moiety is as a result bent away from the reaction center and in the direction of Cl2. The selected torsion angles (Table 3) illustrate this behavior. In the case of Xd the respective bonds are nearly coplanar with the imidazole, but the whole carbene is rotated around the C1-Ru1 axis in such a way that only the C9 carbon from the Mes ring is located above the benzylidene ligand. Structure of Catalyst Xc and Additional Coordination of the Water Molecule. In the case of the Xc structure there is another ligand, namely, a water molecule, coordinating ruthenium. It is worth mentioning that the water is ordered and both H10 and H20 hydrogen atoms belonging to it were located directly from the Fourier map. A pair of strong hydrogen bonds (O2-H2O · O1, O2-O1 distance 2.782(3) Å) connects one Xc molecule with another, related by the crystallographic inversion

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Figure 9. Solid state structure of Xf with thermal ellipsoids at 50% probability. Hydrogen atoms were omitted for clarity. Table 3. Bond Lengths [Å] and Angles [deg] for Xc, Xd, and Xf catalysts Ru(1)-C(1) Ru(1)-C(22) Ru(1)-Cl(1) Ru(1)-S(1) Ru(1)-Cl(2) S(1)-O(1) S(1)-C(28) S(1)-C(29) C(1)-Ru(1)-S(1) Cl(2)-Ru(1)-Cl(1) O(1)-S(1)-Ru(1) C(28)-S(1)-Ru(1) C(29)-S(1)-Ru(1) C(22)-Ru(1)-S(1)-C(28) C(4)-N(1)-C(1)-Ru(1) C(13)-N(2)-C(1)-Ru(1) Ru(1)-O(2) O(2)-H(10) O(2)-H(20) C(22)-Ru(1)-O(2) H10(1)-O(2)-H(20)

Xc

Xd

Xf

2.0888(3) 1.850(2) 2.3883(7) 2.3775(6) 2.3768(7) 1.4801(18) 1.781(2) 1.864(3) 172.86(7) 167.98(2) 122.88(8) 96.72(8) 118.62(9) -5.22(11) -11.7(4) 0.8(4) 2.3037(18) 0.75(3) 0.80(3) 163.05(9) 105(3)

2.096(7) 1.835(6) 2.3288(18) 2.3537(18) 2.3283(19) 1.481(5) 1.779(6) 1.808(8) 177.63(19) 158.01(7) 122.8(2) 99.5(2) 116.6(3) -14.8(3) -5.1(11) 5.1(9)

2.102(3) 1.834(4) 2.3344(9) 2.3318(8) 2.3276(8) 1.478(2) 1.768(4) 1.795(3) 177.15(9) 156.95(4) 121.54(10) 100.94(11) 116.43(11) -2.52(16) 16.9(5) -16.2(4)

center, resulting in formation of dimers and potentially stablilizing the crystal structure. The detailed H-bond geometry is reported in Table 4. The hydrogen points toward the C13-C21 Mes moiety. To the best of our knowledge, it is the first reported structure of the Hoveyda-type catalyst with a water molecule incorporated into the ruthenium coordination sphere. The introduction of the water molecule (in the crystallization of complexes Xc, Xd, and Xf, nondried HPLC grade solvents were used in all cases) as the additional ligand into the ruthenium coordination sphere of Xc yields significant changes in the geometry of the metal surroundings. The metal coordination is now a distorted octahedron, and the benzylidene moiety is significantly twisted with respect to the imidazole plane (C22-Ru1-S1-C28 torsion angle is more than -25°). This results in the elongation of the Ru1-C22 bond by 0.02 Å. The Ru1-S1 bond is also longer by 0.02 Å with respect to Xd and by 0.04 Å with respect to Xf. The Cl-Ru-Cl angle is closer

to 180°, while C1-Ru-S1 gets smaller, resulting in the whole imidazole-based carbene ligand being bent toward the benzylidene. The Ru-Cl bonds get elongated by more than 0.05 Å. The superposition of the catalysts in Figure 10c illustrates the twist of the benzylidene moiety.

Conclusions In summary, we demonstrated that sulfoxide chelating benzylidene ligands can lead to stable Ru initiators. The activity of the resulting sulfoxide bearing Ru-benzylidene complexes can be fine-tuned by altering the structure of these ligands. The most promising complex Xf combines excellent thermodynamic and air stability with good catalytic activity at elevated temperatures. Properties of the family of sulfoxide Ru-benzylidene complexes as initiators in ROMP will be studied and reported in due course.

Experimental Section22 General Syntheses of Catalysts and Metathesis Procedures. Synthesis of Catalyst IXa. A Schlenk tube equipped with a stirring bar was charged with ruthenium complex Ind-II (0.19 g, 0.2 mmol) and CuCl (0.039 g, 0.4 mmol). The tube was flushed with argon and charged with anhydrous toluene (10 mL). Styrene 4a (0.078 g, 0.4 mmol) in anhydrous toluene (5 mL) was added, and the resulting mixture was stirred at 80 °C for 30 min. After this time, TLC indicated complete conversion of the substrate. The resulting mixture was concentrated in vacuo, the residue was redissolved in AcOEt, and the solution was passed through a Paster pipette containing a small amount of cotton and evaporated to dryness. Crude product was purified by column chromatography (using eluents: cyclohexane/ethyl acetate, 10:1 to 1:1 v/v). After evaporation of the solvents, the resulted solid was collected and washed a few times with AcOEt and with cold n-pentane (0.094 g, 0.14 mmol, yield 72%). IXa: green crystals, yield 72%. 1H NMR (500 MHz, CDCl3): δ 1.05 (m, 6H), 2.29 (m, 3H), 2.35-2.45 (m, 12H), 2.55 (s, 6H), (22) For full experimental details and other information see the Supporting Information.

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Organometallics, Vol. 28, No. 9, 2009 2699

Figure 10. Superimposed X-ray structures of complexes Xc (green), Xd (red), and Xf (yellow). The best superposition was based on the ruthenium coordinating atoms. (a) View along the C1-Ru1 bond. (b) View along the Ru1-Cl1 bond. (c) View along the Ru1-C22 bond. The O2 oxygen atom in molecule Xc has been omitted for the sake of easier comparison of the catalysts’ basic structures. Table 4. Hydrogen Bond for Xc [Å and deg] #1 -x+1, -y, -z D-H · · · A

d(D-H)

d(H · · · A)

d(D · · · A)

D-H-A

O(2)-H(2O) · · · O(1)#1

0.80(3)

2.00(3)

2.782(3)

164(3)

3.61 (septet, J ) 6.7 Hz, 1H), 4.15 (s, 4H), 6.74 (m, 1H), 6.95-7.05 (m, 4H), 7.34 (m, 1H), 7. 65-7.70 (m, 1H) 7.72-7.78 (m, 1H), 16.81 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 21.0, 51.7, 121.0, 127.5, 128.9, 129.4, 129.6, 129.7, 133.9, 135.4, 138.1, 138.5, 138.9, 139.0, 156.2, 207.2, 301.7. Anal. Calcd for C31H38Cl2ON2RuS: C, 56.53, H, 5.81, N, 4.87, S, 4.87, Cl, 10.76. Found: C, 56.32, H, 5.79, N, 4.51, S, 5.01, Cl, 10.68. General Synthesis of Catalysts Xa-g. A Schlenk tube equipped with a stirring bar was charged with ruthenium catalyst (Ind-II′) (0.19 g, 0.2 mmol) and CuCl (0.03 g, 0.24 mmol). The tube was flushed with argon and charged with anhydrous toluene (10 mL). A corresponding styrene (0.4 mmol) in anhydrous toluene (5 mL) was added. The resulting solution was stirred at 80 °C for 20-30 min. After this all manipulations can be done without a protective atmosphere of argon. The resulting mixture was concentrated under vacuum, the residue was redissolved in AcOEt, and the solution was passed through a Paster pipette containing a small amount of cotton and evaporated to dryness. Crude product was purified by column chromatography (using eluents: cyclohexane/ethyl acetate, 10:1 to 1:1 v/v). After evaporation of the solvents, the resulting solid was collected and washed a few times with AcOEt or methylene chloride with cold n-pentane (yield 33-60%). Xa: green crystals, yield 60%. 1H NMR (500 MHz, CDCl3): δ 0.96-1.00 (m, 3H), 1.10-1.14 (m, 3H), 1.25-1.35 (m, 2H), 2.32-2.36 (m, 10H), 2.42-2.44 (m, 8H), 3.58-3.62 (m, 1H), 7.00-7.05 (m, 3H), 7.12-7.14 (m, 2H), 7.32-7.38 (m, 1H), 7.62-7.66 (m, 1H), 7.76-7.78 (m, 1H), 16.89 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 18.9, 21.0, 21.1, 26.3, 52.2, 53.2, 120.7, 122.2, 124.6, 124.8, 127.3, 128.3, 128.5, 129.0, 129.4, 129.5, 133.8, 134.5, 135.0, 135.8, 137.2, 137.5, 139.5, 156.4, 176.2, 298.5. Anal. Calcd for C31H38Cl2ON2RuS: C, 56.70, H, 5.53, N, 4.27, S, 4.88, Cl, 10.80. Found: C, 56.60, H, 5.45, N, 4.31, S, 4.79, Cl, 10.61. Xb: light green crystals, yield 57%. 1H NMR (500 MHz, CDCl3): δ 0.90-1.90 (m, 11H), 2.08-2.12 (m, 2H), 2.32-2.36 (m, 10H), 2.42-2.46 (m, 8H), 6.74-6.80 (m, 1H), 7.00-7.20 (m, 4H), 7.32-7.38 (m, 1H), 7.60-7.66 (m, 1H), 7.74-7.78 (m, 1H), 16.88 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 17.7, 18.8, 18.9, 21.0, 21.1, 25.2, 25.3, 25.4, 26.0, 59.9, 120.4, 122.2, 124.6, 127.5, 128.3, 129.1, 129.4, 129.5, 129.9, 133.5, 134.5, 135.0, 136.1, 137.2, 137.5, 139.5, 140.1, 156.5, 176.3, 299.7. Anal. Calcd for C34H40Cl2ON2RuS: C, 58.61, H, 5.79, N, 4.02, S, 4.60, Cl, 10.18. Found: C, 57.24, H, 5.79, N, 4.37, S, 4.62, Cl, 10.81 (the sample was dried overnight under high vacuum before elemental analysis). Xc: dark green crystals, yield 57%. 1H NMR (500 MHz, CDCl3): δ 0.90-1.0 (m, 9H), 2.10-2.46 (m, 18H), 6.70-6.72 (m, 2H),

7.02-7.06 (m, 4H), 7.10-7.14 (m, 2H), 7.30-7.34 (m, 1H), 7.58-7.62 (m, 1H), 7.72-7.76 (m, 1H), 16.99 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 14.2, 18.7, 18.9, 21.1, 23.5, 23.6, 60.3, 63.5, 119.0, 124.7, 124.8, 126.9, 127.9, 129.1, 129.2, 129.4, 129.5 133.0, 136.5, 137.3, 137.4, 139.4, 141.4, 157.6, 174.7, 304.9. Anal. Calcd for C32H38Cl2ON2RuS: C, 57.30, H, 5.71, N, 4.18, S, 4.78, Cl, 10.57. Found: C, 57.24, H, 5.79, N, 4.37, S, 4.62, Cl, 10.81. Xd: green crystals, yield 57%. 1H NMR (500 MHz, CDCl3): δ 2.10-2.26 (m, 12H), 2.33-2.34 (m, 6H), 2.35-2.45 (m, 2H), 3.98-4.01, 4.72-4.75 (m, AB, 2H, CH2), 6.95-6.99 (m, 1H), 7.04-7.06 (m, 1H), 7.08-7.09 (m, 1H), 7.14-7.19 (m, 6H), 7.22-7.23 (m, 2H), 7.24-7.25 (m, 3H), 7.26-7.30 (m, 2H), 7.30-7.32 (m, 1), 16.88 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 17.7, 18.9, 21.1, 21.2, 57.0, 120.9, 122.2, 124.8, 127.3, 128.0, 128.1, 128.4, 128.9, 129.2, 129.5, 129.6, 131.9, 134.1, 134.5, 137.2, 137.4, 139.5, 139.6, 155.0, 175.9, 297.9. Anal. Calcd for C35H36Cl2ON2RuS: C, 59.65, H, 5.15, N, 3.98, S, 4.55, Cl, 10.06. Found: C, 59.60, H, 5.02, N, 3.73, S, 4.32, Cl, 10.24. Xe: dark green crystals, yield 33%. 1H NMR (500 MHz, CDCl3): δ 2.26-2.30 (m, 12H), 2.44 (s, 6H), 2.97 (s, 3H), 6.78-6.80 (m, 1H), 7.04-7.08 (m, 4H), 7.14-7.19 (m, 2H), 7.36-7.38 (m, 2H), 7.70-7.72 (m, 1H), 7.84-7.86 (m, 1H), 16.81 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 14.1, 18.7, 18.7, 18.9, 20.9, 21.1, 40.9, 60.2, 121.1, 124.8, 124.9, 129.1, 129.5, 129.6, 129.8, 134.2, 135.9, 137.1, 137.3 139.6, 141.8, 154.6, 171.0, 175.8, 296.6. Anal. Calcd for C29H32Cl2ON2RuS: C, 55.41, H, 5.13, N, 4.46, S, 5.10, Cl, 11.28. Found: C, 55.32, H, 5.19, N, 4.35, S, 5.26, Cl, 11.18. Xf: light green crystals, yield 60%. 1H NMR (500 MHz, CDCl3): δ 2.10-2.22 (m, 6H), 2.31-2.43 (m, 12H), 6.84-6.88 (m, 1H), 7.00-7.10 (m, 5H), 7.14-7.18 (m, 2H), 7.28-7.30 (m, 2H), 7.31-7.33 (m, 1H), 7.46-7.50 (m, 1H), 7.60-7.64 (m, 2H), 8.04-8.08 (m, 2H), 16.77 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 17.7, 18.8, 21.2, 22.3, 26.1, 26.9, 27.8, 29.9, 121.1, 122.3, 124.1, 125.1, 126.8, 128.9, 129.2, 129.6, 130.2, 131.4, 134.5, 134.8, 135.9, 137.0, 137.4, 139.7, 141.9, 145.5, 148.9, 156.4, 173.9, 295.3. Anal. Calcd for C34H33Cl2O3N3RuS: C, 55.51, H, 4.52, N, 5.71, S, 4.36, Cl, 9.64. Found: C, 55.67, H, 4.69, N, 4.48, S, 4.51, Cl, 9.82. Xg: light green crystals, yield 58%. 1H NMR (500 MHz, CDCl3): δ 2.08-2.12 (s, 2H), 2.20-2.26 (m, 6H), 2.28-2.32 (m, 6H), 2.40-2.44 (m, 6H), 6.78-6.84 (m, 1H), 6.98-7.02 (m, 2H), 7.04-7.08 (m, 2H), 7.10-7.14 (m, 3H), 7.20-7.24 (m, 1H), 7.28-7.30 (m, 1H), 7.32-7.38 (m, 1H), 7.46-7.50 (m, 1H), 7.56-7.60 (m, 1H), 16.85 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 17.8, 18.6, 18.9, 21.1, 21.2, 26.4, 26.9, 120.7, 122.3, 124.9, 126.9, 127.4, 127.7, 129.3, 129.6, 129.8, 130.6, 134.1, 136.1, 137.5, 138.8, 139.6, 142.8, 156.5, 175.2, 184.6, 190.7, 294.4. Anal. Calcd for C34H34Cl2N2RuS: C, 59.12, H, 4.96, N, 4.02, S, 4.64, Cl, 10.27. Found: C, 58.97, H, 4.75, N, 4.23, S, 4.87, Cl, 10.03.

2700 Organometallics, Vol. 28, No. 9, 2009 General Procedure for Preparative RCM Reactions of Using IXa and Xa-g. At 24 °C. Cyclization of N,N-diallyltosylamine S1 was used as a test to compare the activity of catalysts in methylene chloride at 24 °C. Typically 1 mol % of the catalyst (0.002 mmol) was added to a solution of substrate (0.150 mmol) and an internal standard in 7.5 mL methylene chloride at 24 °C. The reaction was running at 24 °C under argon and samples were taken after 5 min, 10 min, 20 min, 30 min, 1 h, 2 h, 4 h, 6 h, and 24 h and analyzed by TLC and GC. At 40 °C. Cycloisomerization of enyne S3 was used as a test to compare the activity of catalysts in methylene chloride at 40 °C. Typically 5 mol % of the catalyst (0.008 mmol) was added to a solution of substrate (0.150 mmol) and an internal standard in 7.5 mL of methylene chloride at 40 °C. The reaction was running at 40 °C under argon and samples were taken after 5 min, 10 min, 20 min, 30 min, 1 h, 1.5 h, 2 h, 4 h and analyzed by TLC and GC. For cyclization of N,N-diallyltosylamine S1 at 40 °C were applied following conditions: 1 mol % of the catalysts (0.003 mmol), 0.25 mmol substrate scale and 12.5 mL of methylene chloride. The reaction was running at 40 °C under argon and samples were taken after 2 h, 4 h, 6 h and analyzed by GC. At 80 °C. Cyclization of diethylallyl(2-methylallyl)malonate S2 was used as a test to compare the activity of catalysts in toluene at 80 °C. Typically 5 mol % of the catalyst (0.005 mmol) was added to a solution of substrate (0.1 mmol) and an internal standard in 5 mL of solvent at 80 °C. The reaction was run at 80 °C under argon and samples were taken after 5 min, 10 min, 20 min, 30 min, 1 h, 2 h, 4 h, 6 h and analyzed by GC.

Szadkowska et al. At 110 °C. Typically 1 mol % of the catalyst (0.004 mmol) was added to the solution of substrate diethyldi(2-methylallyl)malonate (0.350 mmol) S4 and an internal standard in 17.5 mL of toluene at RT. The reaction was running at 110 °C under argon atmosphere for 20 h and samples were taken for GC after: 5 min, 10 min, 15 min, 30 min, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h and 20 h.

Acknowledgment. This work was supported by grant number N204157636, which was provided by the Polish Ministry of Science and Higher Education. K.G. and K.W. thank the Foundation for Polish Science for the “Mistrz” professorships. A.M. acknowledges the “START”-2008 grant for young researchers and also the financial support within the Polish Ministry of Science and Higher Education grant for Ph.D. students number N20403302 33. Single-crystal X-ray measurements were accomplished at the Structural Research Laboratory (SRL) of Chemistry Department, Warsaw University, Poland. S.R.L. has been financially supported by the European Regional Development Fund 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. Supporting Information Available: Complete characterization of all new compounds, catalytic procedures, X-ray crystallographic tables, and data in CIF format. This information is available free of charge via the Internet at http://pubs.acs.org. OM801183G