My watch list
my.chemeurope.com  
Login  

Bischler-Möhlau indole synthesis



The Bischler-Möhlau indole synthesis is a chemical reaction that forms a 2-aryl-indole from a α-bromo-acetophenone and excess aniline.[1][2][3][4][5]

Additional recommended knowledge

In spite of its long history, this classical reaction has received relatively little attention in comparison with other methods for indole synthesis, perhaps owing to the harsh reaction conditions that it requires. Recently, milder methods have been developed, including the use of lithium bromide as a catalyst and an improved procedure involving the use of microwave irradiation.[6][7]

Reaction mechanism

For a reaction with such simple starting materials, the reaction mechanism is surprisingly complex. The first two step involve the reaction of the α-bromo-acetophenone with molecules of aniline to form intermediate 4. The charged aniline forms a decent enough leaving group for an electrophilic cyclization to form intermediate 5, which quickly aromatizes and tautomerizes to give the desired indole 7.

References

  1. ^ Bischler, A. et al.; Ber. 1892, 25, 2860.
  2. ^ Bischler, A. et al.; Ber. 1893, 26, 1336.
  3. ^ Möhlau, R.; Ber. 1881, 14, 171.
  4. ^ Möhlau, R.; Ber. 1882, 15, 2480.
  5. ^ Fischer, E.; Schmitt, T. Ber. 1888, 21, 1071.
  6. ^ Pchalek, K.; Jones, A. W.; Wekking, M. M. T.; Black, D. S. C. Tetrahedron 2005, 61, 77.
  7. ^ Sridharan, V.; Perumal, S.; Avendaño, C.; Menéndez, J. C. Synlett 2006, 91.

See also

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Bischler-Möhlau_indole_synthesis". 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