My watch list
my.chemeurope.com  
Login  

Curtius rearrangement



The Curtius rearrangement (or Curtius reaction or Curtius degradation), as first defined by Theodor Curtius, is a chemical reaction that involves the rearrangement of an acyl azide to an isocyanate.[1][2] Several reviews have been published.[3][4]

The isocyanate can be trapped by a variety of nucleophiles. Often water is added to hydrolyze the isocyanate to an amine.[5] When done in the presence of tert-butanol, the reaction generates Boc-protected amines, useful intermediates in organic synthesis.[6][7]

Carboxylic acids 1 can be easily converted to acyl azides 3 using diphenylphosphoryl azide 2.[8][9][10][11]

Likewise, when the Curtius reaction is performed in the presence of benzyl alcohol, Cbz-protected amines are formed.[12]

Additional recommended knowledge

Contents

Reaction mechanism

The first step of the Curtius rearrangement is the loss of nitrogen gas forming an acyl nitrene (2). Once formed, acyl nitrenes very quickly rearrange by migration of R-group forming the desired isocyanate (3).

Scope

In one variation called the Darapasky Degradation (A. Darapsky, 1936) a Curtius rearrangement takes place as one of the steps from an α-cyanoester to an amino acid [13].

References

  1. ^  Curtius, T. Ber. 1890, 23, 3023.
  2. ^  Curtius, T. J. Prakt. Chem. 1894, 50, 275.
  3. ^  Smith, P. A. S. Org. React. 1946, 3, 337-449. (Review)
  4. ^  Scriven, E. F.; Turnbull, K.; Chem. Rev. 1988, 88, 297-368. (Review)
  5. ^  Kaiser, C.; Weinstock, J. Organic Syntheses, Coll. Vol. 6, p.910 (1988); Vol. 51, p.48 (1971). (Article)
  6. ^  Ende, D. J. a.; DeVries, K. M.; Clifford, P. J.; Brenek, S. J. Org. Proc. Res. Dev. 1998, 2, 382-392.
  7. ^  Lebel, H.; Leogane, O.; Org. Lett. 2005, 7(19), 4107-4110. (doi:10.1021/ol051428b)
  8. ^  Shioiri, T.; Yamada, S. Organic Syntheses, Coll. Vol. 7, p.206 (1990); Vol. 62, p.187 (1984). (Article)
  9. ^  Shioiri, T.; Ninomiya, K.; Yamada, S. J. Am. Chem. Soc. 1972, 94, 6203-6205. (doi:10.1021/ja00772a052)
  10. ^  Ninomiya, K.; Shioiri, T.; Yamada, S. Tetrahedron 1974, 30, 2151-2157.
  11. ^  Wolff, O.; Waldvogel, S. R. Synthesis 2004, 1303-1305.
  12. ^  Jessup, P. J.; Petty, C. B.; Roos, J.; Overman, L. E. Organic Syntheses, Coll. Vol. 6, p.95 (1988); Vol. 59, p.1 (1979). (Article)
  13. ^  http://www.chempensoftware.com/reactions/RXN051.htm

See also

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Curtius_rearrangement". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE