Synthesis of Imidazolium-Tagged Ruthenium Carbene Complex: Remarkable Activity and Reusability in Regard to Olefin Metathesis in Ionic Liquids

Abstract

We have demonstrated the synthesis of a new ionic liquid supported ruthenium carbene complex 1a,b and its applications to olefin metathesis. These catalysts can be used for ring-closing metathesis in the construction of five-to-eight-membered rings with high activity and good recyclability.

ruthenium - catalysis - metathesis - ionic liquids - carbene complexes

References and Notes

<A NAME="RU01908ST-1A">1a</A> Handbook of Metathesis   Vol. 1-3:  Grubbs RH. Wiley-VCH; Weinheim: 2003. 

<A NAME="RU01908ST-1B">1b</A> For selected general review, see: Topics in Organometallic Chemistry   Vol. 1:  Fürstner A. Springer; Berlin, Heidelberg: 1998. 

<A NAME="RU01908ST-1C">1c</A> Schuster M. Blechert S. Angew. Chem., Int. Ed. Engl.  1997,  36:  2037 

<A NAME="RU01908ST-1D">1d</A> Grubbs RH. Chang S. Tetrahedron  1998,  54:  4413 

<A NAME="RU01908ST-1E">1e</A> Fürstner A. Angew. Chem. Int. Ed.  2000,  39:  3012 

<A NAME="RU01908ST-1F">1f</A> Nicolaou KC. Bulger PG. Sarlah D. Angew. Chem. Int. Ed.  2005,  44:  4490 

<A NAME="RU01908ST-1G">1g</A> Hoveyda AH. Zhugralin AR. Nature (London)  2007,  450:  243 

For reviews on cross metathesis, see:

<A NAME="RU01908ST-2A">2a</A> Gibson SE. Keen SP. Top. Organomet. Chem.  1998,  1:  155 

<A NAME="RU01908ST-2B">2b</A> Connon SJ. Blechert S. Angew. Chem. Int. Ed.  2003,  42:  1900 

<A NAME="RU01908ST-2C">2c</A> Vernall AJ. Abell AD. Aldrichimica Acta  2003,  36:  93 

For reviews on enyne metathesis, see:

<A NAME="RU01908ST-3A">3a</A> Mori M. Top. Organomet. Chem.  1998,  1:  133 

<A NAME="RU01908ST-3B">3b</A> Poulsen CS. Madsen R. Synthesis  2003,  1 

<A NAME="RU01908ST-3C">3c</A> Diver ST. Giessert AJ. Chem. Rev.  2004,  104:  1317 

<A NAME="RU01908ST-3D">3d</A> Mori M. J. Mol. Catal. A: Chem.  2004,  213:  73 

<A NAME="RU01908ST-3E">3e</A> Mori M. Adv. Synth. Catal.  2007,  349:  121 

<A NAME="RU01908ST-4A">4a</A> Ionic Liquids in Synthesis   Wasserschid P. Welton T. Wiley-VCH; Weinheim: 2003. 

<A NAME="RU01908ST-4B">4b</A> Welton T. Chem. Rev.  1999,  99:  2071 

<A NAME="RU01908ST-4C">4c</A> Wasserschid P. Keim W. Angew. Chem. Int. Ed.  2000,  39:  3772 

<A NAME="RU01908ST-4D">4d</A> Sheldon R. Chem. Commun.  2001,  2399 

<A NAME="RU01908ST-4E">4e</A> Dupont J. de Souza RF. Suarez PAZ. Chem. Rev.  2002,  102:  3667 

<A NAME="RU01908ST-4F">4f</A> Zhao H. Malhotra SV. Aldrichimica Acta  2002,  35:  75 

<A NAME="RU01908ST-4G">4g</A> Pârvulescu VI. Hardacre C. Chem. Rev.  2007,  107:  2615 

<A NAME="RU01908ST-5">5</A> Chauvin Y. Gilbert B. Guibard I. J. Chem. Soc., Chem. Commun.  1990,  1715 

<A NAME="RU01908ST-6">6</A> Carlin RT. Wilkes JS. J. Mol. Catal.  1990,  63:  125 

<A NAME="RU01908ST-7A">7a</A> Buijsman RC. van Vuuren E. Sterrenburg JG. Org. Lett.  2001,  3:  3785 

<A NAME="RU01908ST-7B">7b</A> Sémeril D. Olivier-Bourbigou H. Bruneau C. Dixneuf PH. Chem. Commun.  2002,  146 

<A NAME="RU01908ST-7C">7c</A> Csihony S. Fischmeister C. Bruneau C. Horváth IT. Dixneuf PH. New J. Chem.  2002,  26:  1667 

<A NAME="RU01908ST-7D">7d</A> Ding X. Lv X. Hui B. Chen Z. Xiao M. Guo B. Tang W. Tetrahedron Lett.  2006,  47:  2921 

<A NAME="RU01908ST-7E">7e</A> Williams DBG. Ajam M. Ranwell A. Organometallics  2006,  25:  3088 

<A NAME="RU01908ST-7F">7f</A> Han S.-H. Hirakawa T. Fukuba T. Hayase S. Kawatsura M. Itoh T. Tetrahedron: Asymmetry  2007,  18:  2484 

<A NAME="RU01908ST-8A">8a</A> Audic N. Clavier H. Mauduit M. Guillemin J.-C.
J. Am. Chem. Soc.  2003,  125:  9248 

<A NAME="RU01908ST-8B">8b</A> Yao Q. Zhang Y. Angew. Chem. Int. Ed.  2003,  42:  3395 

<A NAME="RU01908ST-8C">8c</A> Clavier H. Audic N. Mauduit M. Guillemin J.-C. Chem. Commun.  2004,  2282 

<A NAME="RU01908ST-8D">8d</A> Thurier C. Fischmeister C. Bruneau C. Olivier-Bourbigou H. Dixneuf PH. J. Mol. Catal. A: Chem.  2007,  268:  127 

<A NAME="RU01908ST-8E">8e</A> Rix D. Caïjo F. Laurent I. Gulajski L. Grela K. Mauduit M. Chem. Commun.  2007,  3771 

<A NAME="RU01908ST-9A">9a</A> Wakamatsu H. Blechert S. Angew. Chem. Int. Ed.  2002,  41:  794 

<A NAME="RU01908ST-9B">9b</A> Wakamatsu H. Blechert S. Angew. Chem. Int. Ed.  2002,  41:  2403 

<A NAME="RU01908ST-9C">9c</A> Buschmann N. Wakamatsu H. Blechert S. Synlett  2004,  667 

<A NAME="RU01908ST-10A">10a</A> Kemp DS. Wang S.-W. Mollan RC. Hsia S.-L. Confalone PN. Tetrahedron  1974,  30:  3677 

<A NAME="RU01908ST-10B">10b</A> Nicolosi G. Piattelli M. Sanfilippo C. Tetrahedron  1993,  49:  3143 

<A NAME="RU01908ST-11">11</A> Scholl M. Ding S. Lee CW. Grubbs RH. Org. Lett.  1999,  1:  953 

<A NAME="RU01908ST-12">12</A>

Procedure for the Synthesis of Catalyst 1b
To a solution of 9 (184.9 mg, 0.22 mmol) and CuCl (21.6 mg, 0.22 mmol) in CH₂Cl₂ (20 mL) was added 8b (120.3 mg, 0.26 mmol). The reaction mixture was stirred at reflux for 9 h under argon atmosphere. The volatiles were removed under reduce pressure. The residue was purified by column chromatography on SiO₂ (CH₂Cl₂-acetone, 3:1) to afford 1b (137.2 mg, 68%). ^¹H NMR (400 MHz, CD₂Cl₂): δ = 1.14 (d, J = 6.3 Hz, 6 H), 1.66-1.74 (m, 2 H), 1.89-1.94 (m, 2 H), 2.20-2.65 (br, 18 H), 3.72 (s, 3 H), 4.06 (t, J = 5.7 Hz, 2 H), 4.08 (t, J = 6.9 Hz, 2 H), 4.16 (s, 4 H), 5.64 (sept, J = 6.3 Hz, 1 H), 6.56 (dd, J = 1.3, 7.5 Hz, 1 H), 6.87 (dd, J = 7.5, 8.2 Hz, 1 H), 7.06 (br, 4 H), 7.11 (dd, J = 1.3, 8.2 Hz, 1 H), 7.13 (dd, J = 1.9, 1.9 Hz, 1 H), 7.25 (dd, J = 1.3, 1.9 Hz, 1 H), 8.48 (br, 1 H), 16.57 (s, 1 H). ^¹³C NMR (100 MHz, CD₂Cl₂): δ = 19.6, 21.2, 21.7, 25.4, 26.9, 36.6, 49.9, 51.8, 68.8, 81.0, 115.9, 122.7, 123.9, 124.3, 129.6, 136.0, 136.1, 138.5, 139.3, 140.3, 148.3, 148.6, 210.0, 298.3. IR (KBr): ν = 1574 (w), 1470 (m), 1269 (m) cm^-¹. HRMS-FAB: m/z calcd for C₃₉H₅₁ ^³5Cl₂N₄O₂ ^¹0²Ru: 779.2433; found: 779.2454. Anal. Calcd for C₃₉H₅₁Cl₂F₆N₄O₂PRu: C, 50.65; H, 5.56; N, 6.06. Found: C, 50.62; H, 5.58; N, 5.82.

<A NAME="RU01908ST-13A">13a</A> Garber SB. Kingsbury JS. Gray BL. Hoveyda AH. J. Am. Chem. Soc.  2000,  122:  8168 

<A NAME="RU01908ST-13B">13b</A> Gessler S. Randl S. Blechert S. Tetrahedron Lett.  2000,  41:  9973 

<A NAME="RU01908ST-14">14</A>

Typical Procedure for Metathesis Reaction Promoted by Ionic Liquid Supported Ruthenium Catalyst
To a catalyst solution of 1b (38.1 mg, 0.04 mmol) in [Bmim]PF₆ (1 mL) was added 10 (0.20 mL, 0.82 mmol) in CH₂Cl₂ (9 mL). The reaction mixture was stirred at r.t. until starting material was consumed. After the volatiles were removed under reduce pressure, ionic liquid phase was extracted with Et₂O (several times). The ethereal phase was evaporated to provide 11, and the ionic liquid phase was dried under reduce pressure to use a catalyst solution for the next cycle.