Download PDF
Synlett 2011(7): 969-973  
DOI: 10.1055/s-0030-1259713
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Atom-Economical Synthesis of 2-Aminoimidazoles via [3+2] Annulation Catalyzed by Titanacarborane Monoamide

Yang Wang, Hao Shen, Zuowei Xie*
Department of Chemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, P. R. of China
Fax: +852(2)6035057; e-Mail: zxie@cuhk.edu.hk;
Further Information

Publication History

Received 13 December 2010
Publication Date:
08 March 2011 (online)

    Permissions and Reprints All articles of this category

Abstract

An atom-economical synthesis of 2-aminoimidazoles catalyzed by a titanacarborane monoamide is reported. Reactions of propargylamines with carbodiimides, in the presence of 5 mol% [σ:η ¹:η 5-(OCH2)(Me2NCH2)C2B9H9]Ti(NMe2), afford a new class of substituted 2-aminoimidazoles via [3+2] annulation in good to excellent yields. A possible reaction mechanism is proposed.

Key words

catalysis - heterocycles - hydroamination - imidazole - metallacarborane

    References and Notes

  • For selected examples, see:
  • 1a Fujita M. Nakao Y. Matsunaga S. Seiki M. Itoh Y. Yamashita J. van Soest RWM. Fusetani N. J. Am. Chem. Soc.  2003,  125:  15700 
    Google Scholar
  • 1b Kobayashi J. Tsuda M. Murayama T. Nakamura H. Ohizumi Y. Ishibashi M. Iwamura M. Ohta T. Nozoe S. Tetrahedron  1990,  46:  5579 
    Google Scholar
  • 1c Alvi KA. Crews P. Loughhead DG. J. Nat. Prod.  1991,  54:  1509 
    Google Scholar
  • 1d Capon RJ. Rooney F. Murray LM. Collins E. Sim ATR. Rostas JAP. Butler MS. Carroll AR. J. Nat. Prod.  1998,  61:  660 
    Google Scholar
  • 1e Cutignano A. Bifulco G. Bruno I. Casapullo A. Gomez-Paloma L. Riccio R. Tetrahedron  2000,  56:  3743 
    Google Scholar
  • 1f Ahond A. Bedoya-Zurita M. Colin M. Fizames C. Laboute P. Lavelle F. Laurent D. Poupat C. Pusset J. Pusset M. Thoison O. Potier P.
    C. R. Acad. Sci., Ser. II  1988,  307:  145 
    Google Scholar
  • 1g Picman AK. Arnason JT. Lambert JDH. J. Nat. Prod.  1986,  49:  556 
    Google Scholar
  • 1h Tsukamoto S. Kato H. Hirota H. Fusetani N.
    J. Nat. Prod.  1996,  59:  501 
    Google Scholar
  • 1i Carmely S. Kashman Y. Tetrahedron Lett.  1987,  28:  3003 
    Google Scholar
  • 1j Carmely S. Ilan M. Kashman Y. Tetrahedron  1989,  45:  2193 
    Google Scholar
  • 1k Walker RP. Faulkner DJ. Van Engen D. Clardy J. J. Am. Chem. Soc.  1981,  103:  6772 
    Google Scholar
  • 1l Albizati KF. Faulkner DJ.
    J. Org. Chem.  1985,  50:  4163 
    Google Scholar
  • For selected reviews of synthesis and activity of 2-aminoimidazole alkaloids, see:
  • 2a Weinreb SM. Nat. Prod. Rep.  2007,  24:  931 
    Google Scholar
  • 2b Hoffmann H. Lindel T. Synthesis  2003,  1753 
    Google Scholar
  • 2c Sullivan JD. Giles RL. Looper RE. Curr. Bioact. Compd.  2009,  5:  39 
    Google Scholar
  • 3a Norris TO. McKee RL. J. Am. Chem. Soc.  1954,  77:  1056 
    Google Scholar
  • 3b Lawson A. J. Chem. Soc.  1956,  307 
    Google Scholar
  • 3c Kreutzberger A. J. Org. Chem.  1962,  27:  886 
    Google Scholar
  • 3d Lancini GC. Lazzari E. J. Antibiot.  1966,  3:  152 
    Google Scholar
  • 3e Lancini GC. Lazzari E. Arioli V. Bellani P. J. Med. Chem.  1969,  12:  775 
    Google Scholar
  • 3f Little TL. Webber SE. J. Org. Chem.  2004,  69:  7299 
    Google Scholar
  • 3g Nishimura T. Kitajima K.
    J. Org. Chem.  1979,  44:  818 
    Google Scholar
  • 3h Ryckmans T. Schulte K. Viehe H.-G. Bull. Soc. Chim. Belg.  1997,  106:  553 
    Google Scholar
  • 3i Thangavel N. Murgesh K. Asian J. Chem.  2005,  17:  2769 
    Google Scholar
  • 3j Casagrande C. Ferrini R. Miragoli G. Ferrari G. Farmaco, Ed. Sci.  1972,  27:  715 
    Google Scholar
  • 4a Hassner A. Munger P. Belinka BA. Tetrahedron Lett.  1982,  23:  699 
    Google Scholar
  • 4b Daninos S. Al Mourabit A. Ahond A. Zurita MB. Poupat C. Potier P. Bull. Soc. Chim. Fr.  1994,  131:  590 
    Google Scholar
  • 4c Danios-Zegal S. Mourabit AA. Ahond A. Poupat C. Potier P. Tetrahedron  1997,  53:  7605 
    Google Scholar
  • 4d Jarosinski MA. Anderson KA. J. Org. Chem.  1991,  56:  4058 
    Google Scholar
  • 4e Meketa ML. Weinreb SM. Org. Lett.  2006,  8:  1443 
    Google Scholar
  • 5 Giles RL. Sullivan JD. Steiner AM. Looper RE. Angew. Chem. Int. Ed.  2009,  48:  3116 
    CrossrefPubMedGoogle Scholar
  • 6 Ermolat’ev DS. Bariwal JB. Steenackers HPL. De Keersmaecher SCJ. Van der Eycken EV. Angew. Chem. Int. Ed.  2010,  49:  9465 
    CrossrefGoogle Scholar
  • 7a Shen H. Chan H.-S. Xie Z. Organometallics  2007,  26:  2694 
    Google Scholar
  • 7b Shen H. Xie Z. J. Organomet. Chem.  2009,  694:  1652 
    Google Scholar
  • 8 Shen H. Chan H.-S. Xie Z. Organometallics  2006,  25:  5515 
    CrossrefGoogle Scholar
  • 9 Shen H. Xie Z. J. Am. Chem. Soc.  2010,  132:  11473 
    CrossrefPubMedGoogle Scholar
  • 10 Shen H. Chan H.-S. Xie Z. Organometallics  2008,  26:  2685 
    Google Scholar
  • For examples, see:
  • 11a Ong T.-G. O’Brien JS. Korobkov I. Richeson DS. Organometallics  2006,  25:  4728 
    Google Scholar
  • 11b Kubiak R. Prochnow I. Doye S. Angew. Chem. Int. Ed.  2009,  48:  1153 
    Google Scholar
  • 11c Bexrud JA. Beard JD. Leitch DC. Schafer LL. Org. Lett.  2005,  7:  1959 
    Google Scholar
  • 11d Walsh PJ. Baranger AM. Bergman RG. J. Am. Chem. Soc.  1992,  114:  1708 
    Google Scholar
  • 11e Pohlki F. Doye S. Chem. Soc. Rev.  2003,  32:  104 
    Google Scholar
  • 15 The conversion of guanidinoalkynes into imidazoles without the assistance of a metal catalyst has been reported, see: Oyler AR. Naldi RE. Stefanick SM. Lloyd JR. Graden DA. Cotter ML. J. Pharm. Sci.  1989,  78:  21 
    CrossrefGoogle Scholar
12

Some reactions were complete within 18 h, although the reaction of 2a and 3a was finished in 8 h.

13

Typical procedure for a preparative scale reaction of 2 with 3: A 50-mL Schlenk bottle was charged with a toluene solution (20 mL) of catalyst 1 (0.05 mmol), to which was added 2 (1.0 mmol) and 3 (1.0 mmol). The flask was closed in order to prevent the evaporation of amine. The reaction mixture was then heated at 115 ˚C for 18 h. After removal of the solvent, the residue was subject to flash column chromatographic separation on silica gel (230-400 mesh) to give 4.

14

CCDC-803540 contains the supplementary crystallographic data of 4aa for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Center via http://www.ccdc.cam.ac.uk/data_request/cif.