PDF herunterladen
Synthesis 2010(18): 3087-3090  
DOI: 10.1055/s-0030-1258154
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Facile Conversion of Thioamides into the Corresponding Amides in the Presence of Tetrabutylammonium Bromide

Kiyofumi Inamoto*, Mitsugu Shiraishi, Kou Hiroya, Takayuki Doi*
Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
Fax: +81(22)7956864; e-Mail: inamoto@mail.pharm.tohoku.ac.jp; e-Mail: doi_taka@mail.pharm.tohoku.ac.jp;
Weitere Informationen

Publikationsverlauf

Received 13 April 2010
Publikationsdatum:
07. Juli 2010 (online)

    Lizenzen und Reprints Alle Artikel dieser Rubrik

Abstract

Desulfurization of thioamides was accomplished using a semicatalytic amount of Bu4NBr. The corresponding amides were obtained in high yields, with good functional group compatibility.

Key words

desulfurization - thioamides - amides - tetrabutylammonium bromide - thioketones

    References

  • 1 For a review, see: Corsaro A. Pistarà V. Tetrahedron  1998,  54:  15027 
    CrossrefSuche in Google Scholar
  • For selected recent reports, see:
  • 2a Bahrami K. Khodaei MM. Tirandaz Y. Synthesis  2009,  369 
  • 2b Shibahara F. Suenami A. Yoshida A. Murai T. Chem. Commun.  2007,  2354 
  • 2c Pourali AR. Monatsh. Chem.  2005,  136:  733 
    Suche in Google Scholar
  • 2d Mohammadpoor-Baltork I. Memarian HR. Bahrami K. Monatsh. Chem.  2004,  135:  411 
    Suche in Google Scholar
  • 2e Mohammadpoor-Baltork I. Memarian HR. Hajipour AR. Bahrami K. Bull. Korean Chem. Soc.  2003,  24:  1002 
    Suche in Google Scholar
  • 2f Mohammadpoor-Baltork I. Khodaei MM. Nikoofar K. Tetrahedron Lett.  2003,  44:  591 
    Suche in Google Scholar
  • 2g Mohammadpoor-Baltork I. Sadeghi MM. Esmayilpour K. Synth. Commun.  2003,  33:  953 
    Suche in Google Scholar
  • 2h Movassagh B. Lakouraj MM. Ghodrati K. Synth. Commun.  2000,  30:  2353 
    Suche in Google Scholar
  • 4a Although the precise reaction mechanism of this cyclization affording 2-phenylbenzothiazole (3) is not clear at this point, tetrabutylammonium cation mediated Hugershoff-type reaction might be occurring, see: Metzger J. In Comprehensive Heterocyclic Chemistry   Vol. 6:  Katritzky AR. Rees CW. Pergamon Press; Oxford: 1984.  p.323 
    Suche in Google Scholar
  • 4b We recently reported a synthetic method for 2-arylbenzothiazoles via Pd-catalyzed C-H functionalization, see: Inamoto K. Hasegawa C. Hiroya K. Doi T. Org. Lett.  2008,  10:  5147 
    Suche in Google Scholar
  • 6 For previous reports on the use of Bu4NBr in oxidation reactions of hydrocarbons, see: Harustiak M. Hronec M. Ilavsky J. React. Kinet. Catal. Lett.  1988,  37:  215 ; and references cited therein
    CrossrefSuche in Google Scholar
  • The reaction mechanism of this desulfurization process is not yet clear at present. There are several reports on the desulfurization of thiocarbonyl compounds using molecular oxygen with photoirradiation, see for example:
  • 7a Ramnath N. Ramesh V. Ramamurthy V. J. Org. Chem.  1983,  48:  214 
    Suche in Google Scholar
  • 7b Suzuki N. Sano K. Wakatsuki S. Tani N. Izawa Y. Bull. Chem. Soc. Jpn.  1982,  55:  3351 
    Suche in Google Scholar
  • 7c Tamagaki S. Akatsuka R. Nakamura M. Kozuka S. Tetrahedron Lett.  1979,  38:  3665 
    Suche in Google Scholar
  • 7d Ishibe N. Odani M. Sunami M. J. Chem. Soc., Chem. Commun.  1971,  118 
  • 9 Bogert MT. Wise LE. J. Am. Chem. Soc.  1910,  32:  1494 
    CrossrefSuche in Google Scholar
  • 10 Solak N. Rollas S. ARKIVOC  2006,  (xii):  173 
    Suche in Google Scholar
  • 11 Bowman WR. Heaney H. Jordan BJ. Tetrahedron  1991,  47:  10119 
    Suche in Google Scholar
3

Indeed, only little is known about the functional-group compatibility of this kind of desulfurization process in previous reports.

5

MeCN and DMA had a yield-improving effect similar to DMF (75% and 73% yield of 2, respectively). Use of other solvents, such as 1,4-dioxane, toluene, and 2-BuOH resulted in lower yields.

8

Unfortunately, an aliphatic thioamide such as N-phenyl-thioacetamide did not undergo the desulfurization, the reaction of which resulted in the recovery of a large amount of the starting material.