Download PDF
Synlett 2010(14): 2087-2092  
DOI: 10.1055/s-0030-1258131
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Mild, Efficient, and Robust Method for Stereocomplementary Iron-Catalyzed Cross-Coupling Using (E)- and (Z)-Enol Tosylates

Hiroshi Nishikado, Hidefumi Nakatsuji, Kanako Ueno, Ryohei Nagase, Yoo Tanabe*
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
Fax: +81(79)5659077; e-Mail: tanabe@kwansei.ac.jp;
Further Information

Publication History

Received 3 May 2010
Publication Date:
09 July 2010 (online)

    Permissions and Reprints All articles of this category

Abstract

Iron-catalyzed cross-coupling of Grignard reagents (RMgX) with (E)- and (Z)-enol tosylates proceeded smoothly to give a variety of the corresponding (E)- and (Z)-trisubstituted α,β-unsaturated methyl esters (total 30 examples; 55-98% yield). The simple, mild, stereoretentive method utilized iron(III) chloride (FeCl3), iron(III) acetylacetonate [Fe(acac)3], and iron(III) tris(dibenzylmethane) [Fe(dbm)3]. The (E)- and (Z)-enol tosylates were readily prepared by the reported stereocomplementary tosylation method from methyl β-keto esters or α-formyl esters. Methyl α-formyl esters were obtained via a practical and robust TiCl4-Et3N-mediated α-formylation of methyl esters with methyl formate.

Key words

cross-coupling - iron - stereoselective synthesis - enol ­tosylate - α,β-unsaturated ester

    References and Notes

  • Recent books:
  • 1a Iron Catalysis in Organic Chemistry   Plietker B. Wiley-VCH; Weinheim: 2008. 
    Google Scholar
  • 1b Nakamura M. Ito S. In Modern Arylation Methods   Ackermann L. Wiley-VCH; Weinheim: 2009.  p.155 
    Google Scholar
  • Recent reviews:
  • 1c Fürstner A. Leitner A. Angew. Chem. Int. Ed.  2002,  41:  609 
    Google Scholar
  • 1d Bolm C. Legros J. Paih JL. Zani L. Chem. Rev.  2004,  104:  6217 
    Google Scholar
  • 1e Shinokubo H. Oshima K. Eur. J. Org. Chem.  2004,  2081 
    Google Scholar
  • 1f Fürstner A. Martin R. Chem. Lett.  2005,  34:  624 
    Google Scholar
  • 1g Bauer EB. Curr. Org. Chem.  2008,  12:  1341 
    Google Scholar
  • A recent iron-catalyzed cross-coupling of zinc reagents with alkyl tosylates:
  • 1h Ito S. Fujiwara Y. Nakamura E. Nakamura M. Org. Lett.  2009,  11:  4306 ; and relevant references cited therein
    Google Scholar
  • 2a Wothers P. Greeves N. Warren S. Clayden J. Organic Chemistry   Oxford; New York: 2001.  p.817 
    Google Scholar
  • 2b Smith MB. March J. Advanced Organic Chemistry   6th ed.:  Wiley; New York: 2007.  p.1375 
    Google Scholar
  • For examples:
  • 3a Zimmerman HE. Ahramjian L. J. Am. Chem. Soc.  1959,  81:  2086 
    Google Scholar
  • 3b Sai H. Ohmizu H. Tetrahedron Lett.  1999,  40:  5019 
    Google Scholar
  • 3c Feuillet FJP. Robinson DEJ. Bull SD. Chem. Commun.  2003,  2184 
    Google Scholar
  • 3d Mani NS. Mapes CM. Wu J. Deng X. Jones TK. J. Org. Chem.  2006,  71:  5039 
    Google Scholar
  • 5 Hayashi T. Inoue K. Taniguchi N. Ogasawara M. J. Am. Chem. Soc.  2001,  123:  9918 
    CrossrefPubMedGoogle Scholar
  • For examples:
  • 6a Scheiper B. Bonnekessel M. Krause H. Fürstner A. J. Org. Chem.  2004,  69:  3943 
    Google Scholar
  • 6b Babinski D. Soltani O. Frantz DE. Org. Lett.  2008,  10:  2901 
    Google Scholar
  • 6c Specklin S. Bertus P. Weibel JM. Pale P. J. Org. Chem.  2008,  73:  7845 
    Google Scholar
  • 6d Maity P. Lepore SD. J. Org. Chem.  2009,  74:  158 
    Google Scholar
  • Alkenyl and dienyl phospahates:
  • 6e Cahiez G. Gager O. Habiak V. Synthesis  2008,  2636 
    Google Scholar
  • 6f Cahiez G. Habiak V. Gager O. Org. Lett.  2008,  10:  2389 
    Google Scholar
  • Recent alkenyl pivalates:
  • 6g Li B.-J. Xu L. Wu Z.-H. Guan B.-T. Sun C.-L. Wang B.-Q. Shi Z.-J. J. Am. Chem. Soc.  2009,  131:  14656 
    Google Scholar
  • 7a Nakatsuji H. Ueno K. Misaki T. Tanabe Y. Org. Lett.  2008,  10:  2131 
    Google Scholar
  • 7b Nakatsuji H. Nishikado H. Ueno K. Tanabe Y. Org. Lett.  2009,  11:  4258 
    Google Scholar
  • 8a Wakasugi K. Iida A. Misaki T. Nishii Y. Tanabe Y. Adv. Synth. Catal.  2003,  345:  1209 
    Google Scholar
  • 8b Yasukochi H. Atago T. Tanaka A. Yoshida E. Kakehi A. Nishii Y. Tanabe Y. Org. Biomol. Chem.  2008,  6:  540 
    Google Scholar
  • Utilization of relevant reactive ammonium intermediates between RCOCl and NMI:
  • 8c Misaki T. Nagase R. Matsumoto K. Tanabe Y. J. Am. Chem. Soc.  2005,  127:  2854 
    Google Scholar
  • 8d Iida A. Nakazawa S. Okabayashi T. Horii A. Misaki T. Tanabe Y. Org. Lett.  2006,  8:  5215 
    Google Scholar
  • 8e Nakatsuji H. Morita J. Misaki T. Tanabe Y. Adv. Synth. Catal.  2006,  348:  2057 
    Google Scholar
  • 8f Nakatsuji H. Morimoto M. Misaki T. Tanabe Y. Tetrahedron  2007,  50:  12071 
    Google Scholar
  • 10a Cahiez G. Avedissaian H. Synthesis  1998,  1199 
    Google Scholar
  • 10b Cahiez G. Marquais S. Pure Appl. Chem.  1996,  68:  53 
    Google Scholar
4

Ref. 2b, p. 1501.

9

In the absence of Fe(III) catalysts, the major side reaction was an addition to the ester moiety and the desired coupling products were not obtained. The basic reactivity order of the Fe(III) catalysts is as follows: Fe(dbm)3 > Fe(acac)3 with NMP > Fe(acac)3 > FeCl3. Due to the accessibility and cheapness, the choice order was FeCl3, Fe(acac)3, and Fe(dbm)3; For (E)-1, (E)-3, and (Z)-3, FeCl3 sufficiently worked well, whereas reactive Fe(dbm)3 was required for (Z)-1.

11

Yields of the traditional basic method range from 0 to 50%. Reexamination of NaH-promoted α-formylation using an aliphatic simple esters, Me(CH2)4CO2Me, in our hands, however, was not reproducible under identical conditions. These strongly basic and heterogeneous conditions might be troublesome.