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Synlett 2008(12): 1781-1784  
DOI: 10.1055/s-2008-1078548
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Palladium N-Heterocyclic Carbene Catalysts for Synthesis of Diaryl Ethers

Mitat Akkoça, Nevin Gürbüza, Engin Çetinkayab, Ismail Özdemir*a
a Chemistry Department, Faculty of Science and Arts, Inönü University, 44280 Malatya, Turkey
b Department of Chemistry, Ege University, 35100 Bornova-zmir, Turkey
Fax: +90(422)3410212; e-Mail: iozdemir@inonu.edu.tr;
Further Information

Publication History

Received 3 March 2008
Publication Date:
02 July 2008 (online)

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Abstract

Novel functionalized 1,3-dialkylimidazolinium (LH) salts as precursors for N-heterocyclic carbenes (NHCs) have been prepared and successfully applied in the palladium-catalyzed synthesis of diaryl ethers and arylation of benzaldehydes. An efficient catalyst system was prepared in situ from Pd(OAc)2, 1,3-dialkylimidazolinium bromides (LHBr), and NaH.

Key words

C-O bond formation - etherification - palladium ­coupling - N-heterocyclic carbene.

    References and Notes

  • 1a Yang BH. Buchwald SL. J. Organomet. Chem.  1999,  576:  125 
    Google Scholar
  • 1b Hartwig JF. Angew Chem. Int. Ed.  1998,  37:  2046 
    Google Scholar
  • 2 Theil F. Angew. Chem. Int. Ed.  1999,  38:  2345 
    CrossrefPubMedGoogle Scholar
  • 3 Ullmann F. Chem. Ber.  1904,  37:  853 
    Google Scholar
  • 4 Lindley J. Tetrahedron  1984,  40:  1433 
    CrossrefGoogle Scholar
  • 5a Frlan R. Kikelj D. Synthesis  2006,  2271 
    Google Scholar
  • 5b Beletskaya IP. Cheprakov AV. Coord. Chem. Rev.  2004,  248:  2337 
    Google Scholar
  • 5c Kunz K. Scholz U. Ganzer D. Synlett  2003,  2428 
    Google Scholar
  • 6 Ouali A. Spindler J.-F. Jutand A. Taillefer M. Adv. Synth. Catal.  2007,  349:  1906 
    CrossrefGoogle Scholar
  • 7a Buck E. Song ZJ. Tschaen D. Dormer PG. Volante RP. Reider PJ. Org. Lett.  2002,  4:  1623 
    Google Scholar
  • 7b Wipf P. Jung JK. J. Org. Chem.  2000,  65:  6319 
    Google Scholar
  • 7c Miao T. Wang L. Tetrahedron Lett.  2007,  48:  95 
    Google Scholar
  • 7d Lipshutz BH. Unger JB. Taft BR. Org. Lett.  2007,  9:  1089 
    Google Scholar
  • 7e Cai Q. Zou BL. Ma DW. Angew. Chem.  2006,  118:  1298 
    Google Scholar
  • 7f Luo YT. Wu JX. Ren RX. Synlett  2003,  1734 
    Google Scholar
  • 7g Gujadhur R. Venkataraman D. Synth. Commun.  2001,  31:  2865 
    Google Scholar
  • 7h Marcoux JF. Doye S. Buchwald SL. J. Am. Chem. Soc.  1997,  119:  10539 
    Google Scholar
  • 7i Kalinin AV. Bower JF. Riebel P. Snieckus V. J. Org. Chem.  1999,  64:  2986 
    Google Scholar
  • 7j Paine AJ. J. Am. Chem. Soc.  1987,  109:  1496 
    Google Scholar
  • 8a Mann G. Incarvito C. Rheingold AL. Hartwig JF. J. Am. Chem. Soc.  1999,  121:  3224 
    Google Scholar
  • 8b Aranyos A. Old DW. Kiyomori A. Wolfe JP. Sadighi JP. Buchwald SL. J. Am. Chem. Soc.  1999,  121:  4369 
    Google Scholar
  • 8c Harkal S. Kumar K. Michalik D. Zapf A. Jackstell R. Rataboul F. Riermeier T. Monsees A. Beller M. Tetrahedron Lett.  2005,  46:  3237 
    Google Scholar
  • 9a Mann G. Hartwig JF. J. Am. Chem. Soc.  1996,  118:  13109 
    Google Scholar
  • 9b Palucki M. Wolfe JP. Buchwald SL. J. Am. Chem. Soc.  1997,  119:  3395 
    Google Scholar
  • 9c Mann G. Hartwig JF. Tetrahedron Lett.  1997,  38:  8005 
    Google Scholar
  • 10 Herrmann WA. In Applied Homogeneous Catalysis with Organometallic Compounds   Cornils B. Herrmann WA. Wiley-VCH; Weinheim: 1996.  p.712 
    Google Scholar
  • 11a Bourissou D. Guerret O. Gabbai FP. Bertrand G. Chem. Rev.  2000,  100:  39 
    Google Scholar
  • 11b Hahn FE. Angew. Chem. Int. Ed.  2006,  45:  1348 
    Google Scholar
  • 11c Herrmann WA. Angew. Chem. Int. Ed.  2002,  41:  1290 
    Google Scholar
  • 11d Peris E. Crabtree RH. Coord. Chem. Rev.  2004,  248:  2239 
    Google Scholar
  • 12a Dragutan V. Dragutan I. Delaude L. Demonceau A. Coord. Chem. Rev.  2007,  251:  765 
    Google Scholar
  • 12b Lin IJB. Vasam CS. Coord. Chem. Rev.  2007,  251:  642 
    Google Scholar
  • 12c Gonzalez SD. Nolan SP. Coord. Chem. Rev.  2007,  251:  874 
    Google Scholar
  • 12d Yen SK. Koh LL. Hahn FE. Huynh HV. Hor TSA. Organometallics  2006,  25:  5105 
    Google Scholar
  • 13a Hahn FE. Jahnke MC. Pape T. Organometallics  2007,  26:  150 
    Google Scholar
  • 13b Lavallo V. Canac Y. DeHope A. Donnadieu B. Bertrand G. Angew. Chem. Int. Ed.  2005,  44:  7236 
    Google Scholar
  • 13c Lavallo V. Canac Y. Prasang C. Donnadieu B. Bertrand G. Angew. Chem. Int. Ed.  2005,  44:  5705 
    Google Scholar
  • 14a Nishioka T. Shibata T. Kinoshita I. Organometallics  2007,  26:  1126 
    Google Scholar
  • 14b Gnanamgari D. Moores A. Rajaseelan E. Crabtree RH. Organometallics  2007,  26:  1226 
    Google Scholar
  • 14c Rüther T. Braussaud N. Cavell KJ. Organometallics  2001,  20:  1247 
    Google Scholar
  • 15a McGuinness DS. Mueller W. Wasserscheid WP. Cavell KJ. Skelton BW. White AH. Englert U. Organometallics  2002,  21:  175 
    Google Scholar
  • 15b Nielsen DJ. Cavell KJ. Skelton BW. White AH. Organometallics  2006,  25:  4850 
    Google Scholar
  • 15c Iglesias M. Beetstra DJ. Stasch A. Horton PN. Hursthouse MB. Coles SJ. Cavell KJ. Devrisi A. Fallis IA. Organometallics  2007,  26:  4800 
    Google Scholar
  • 16 Böhm VPW. Gstöttmayr CWK. Herrmann WA. J. Organomet. Chem.  2000,  595:  186 
    CrossrefGoogle Scholar
  • 17a Özdemir . Gök Y. Gürbüz N. Yaar S. Çetinkaya E. Çetinkaya B. Polish J. Chem.  2004,  78:  2141 
    Google Scholar
  • 17b Özdemir . Gök Y. Gürbüz N. Çetinkaya E. Çetinkaya B. Synth. Commun.  2004,  34:  4135 
    Google Scholar
  • 17c Özdemir . Alc B. Gürbüz N. Çetinkaya E. Çetinkaya B. J. Mol. Catal. A: Chem.  2004,  217:  37 
    Google Scholar
  • 18 Özdemir . Demir S. Çetinkaya B. Gourlaouen C. Maseras F. Bruneau C. Dixneuf PH. J. Am. Chem. Soc.  2008,  130:  1156 
    CrossrefPubMedGoogle Scholar
  • 19 Çetinkaya E. Hitchcock PB. Jasim HA. Lappert MF. Spyropoulos K. J. Chem. Soc., Perkin Trans. 1  1992,  56 
    Google Scholar
  • 21a Özdemir . Demir S. Yaar S. Çetinkaya B. Appl. Organomet. Chem.  2005,  19:  55 
    Google Scholar
  • 21b Demir S. Özdemir . Çetinkaya B. Appl. Organomet. Chem.  2006,  20:  254 
    Google Scholar
  • 21c Özdemir . Demir S. Çetinkaya B. Synlett  2007,  889 
    Google Scholar
  • 21d Gürbüz N. Özdemir . Çetinkaya B. Tetrahedron Lett.  2005,  46:  2273 
    Google Scholar
20

General Procedure for the Synthesis of 1,3-Dialkyl-imidazolinium Bromides 2: To a solution of 1-(methoxy-ethyl)imidazoline (1 mmol) in DMF (3 mL), alkyl halide (1.1 mmol) was added and the resulting solution was stirred for 1 h at r.t. and heated for 12 h at 80 ˚C. Et2O (10 mL) was added to the reaction mixture. A white solid was precipitated in this period. The precipitate was then crystallized from EtOH-Et2O (1:2).
1-(2-Methoxyethyl)-3-(cyclohexylmethyl)imidazolinium Bromide (2a): yield: 2.65 g (87%); mp 29 ˚C. IR: 1465 (C=N) cm- ¹. ¹H NMR (300.13 MHz, CDCl3): δ = 3.11 (s, 3 H, OMe), 3.38 (t, J = 4.8 Hz, 2 H, NCH2CH 2O), 3.59 (t, J = 4.8 Hz, 2 H, NCH 2CH2O), 3.79, 3.89 (m, 4 H, NCH2CH2N), 0.72-1.41 (m, 11 H, CH2C6 H 11), 3.15 (d, 2 H, CH 2C6H11), 9.20 (s, 1 H, 2-CH). ¹³C NMR (75.46 MHz, DMSO): δ = 47.3, 48.8 (NCH2CH2N), 68.6 (OMe), 58.5 (NCH2 CH2O), 53.8 (NCH2CH2O), 49.2 (CH2C6H11), 25.0, 25.6, 34.9, 39.7 (CH2 C 6H11), 158.2 (2-CH). Anal. Calcd for C13H25N2OBr: C, 51.15; H, 8.25; N, 9.18. Found: C, 51.23; H, 8.18; N, 9.24.
1-(2-Methoxyethyl)-3-(2,3,5,6-tetramethylbenzyl)im-idazolinium Bromide (2b): yield: 3.22 g (91%); mp 156-157 ˚C. IR: 1649 (C=N) cm- ¹. ¹H NMR (300.13 MHz, CDCl3): δ = 2.20 [s, 6 H, CH2C6H(CH 3)4-2,6], 2.22 [s, 6 H, CH2C6H(CH 3)4-3,5], 3.32 (s, 3 H, OMe), 3.60 (t, J = 8.0 Hz, 2 H, NCH2CH 2O), 4.04 (t, J = 8.0 Hz, 2 H, NCH 2CH2O), 3.76-3.81 (m, 4 H, NCH2CH2N), 4.89 [s, 2 H, CH 2C6H(CH3)4-2,3,5,6], 6.97 [s, 1 H, CH2C6 H(CH3)4-2,3,5,6], 9.22 (s, 1 H, 2-CH). ¹³C NMR (75.46 MHz, CDCl3): δ = 14.9 [CH2C6H(CH3)4-2,6], 19.5 [CH2C6H(CH3)4-3,5], 48.4 [CH2C6H(CH3)4-2,3,5,6], 47.0 (NCH2 CH2N), 68.3 (OMe), 57.9 (NCH2 CH2O), 45.9 (NCH2CH2O), 127.3, 131.8, 132.9, 133.7 [CH2 C 6H(CH3)4], 157.5 (2-CH). Anal. Calcd for C17H27N2OBr: C, 57.47; H, 7.66; N, 7.88. Found: C, 57.39; H, 7.61; N, 7.93.
1-(2-Methoxyethyl)-3-(2,3,4,5,6-pentamethylbenzyl)im-idazolinium Bromide (2c): yield: 3.28 g (89%); mp 182-183 ˚C. IR: 1648 (C=N) cm- ¹. ¹H NMR (CDCl3): δ = 2.22 [s, 6 H, CH2C6 (CH 3)5-2,6], 2.25 [s, 3 H, CH2C6 (CH 3)5-4], 2.30 [s, 6 H, CH2C6 (CH 3)5-3,5], 3.35 (s, 3 H, OMe), 3.63 (t, J = 8.0 Hz, 2 H, NCH2CH 2O), 4.09 (t, J = 8.0 Hz, 2 H, NCH 2CH2O), 3.83-3.88 (m, 4 H, NCH2CH2N), 4.91 [s, 2 H, CH 2C6(CH3)5-2,3,4,5,6], 9.15 (s, 1 H, 2-CH). ¹³C NMR (75.46 MHz, CDCl3): δ = 17.1 [CH2C6(CH3)5-2,3,5,6], 17.4 [CH2C6(CH3)5-4], 49.6 [CH2C6(CH3)5], 69.4 (OMe), 59.0 (NCH2 CH2O), 48.3 (NCH2CH2O), 47.5, 48.2 (NCH2 CH2N), 125.9, 133.6, 136.7 [CH2 C 6(CH3)5], 157.5 (2-CH). Anal. Calcd for C18H29N2OBr: C, 58.53; H, 7.91; N, 7.58. Found: C, 58.47; H, 7.81; N, 7.62.
General Procedure for the Diaryl Ether Formation: A dried Schlenk tube was charged with NaH (1.4 mmol) and purged with argon. The phenol (1.1 mmol) and toluene (3 mL) were added, and the mixture was stirred at 100 ˚C for 30 min under argon. The reaction mixture was cooled to r.t. and the tube was charged with Pd(OAc)2 (2.0 mmol%), 1,3-dialkyimidazolinium bromides 2 (4.0 mmol%) and aryl chloride (1.0 mmol). The mixture was heated at 100 ˚C for 20 h. At the conclusion of the reaction, the mixture was cooled, extracted with Et2O, filtered through a pad of silica gel with copious washings, concentrated and purified by flash chromatography on silica gel. The purity of the compounds was checked by GC and yields are based on the aryl chloride.