Subscribe to RSS
DOI: 10.1055/s-2004-829062
Reactions of Cyclopropyl Aryl Ketones with Sulfonamides Mediated by Zr(OTf)4: Cascade Preparation of 5-Aryl-3,4-dihydro-2H-pyrrole
Publication History
Publication Date:
01 July 2004 (online)
Abstract
We found that the Lewis acid Zr(OTf)4 can effectively promote the ring-opening reaction of cyclopropyl aryl ketones with sulfonamides. By controlling the reaction conditions, we could obtain the ring-opened products 3 and the cyclized products 5 in moderate to good yields. This process provides a novel and efficient route for the synthesis of 5-aryl-3,4-dihydro-2H-pyrrole in the presence of a Lewis acid.
Key words
cyclopropyl aryl ketones - Lewis acid - Zr(OTf)4 - ring-opening reaction - sulfonamides - cyclization - 5-aryl-3,4-dihydro-2H-pyrrole
- For reviews on the use of cyclopropanes in organic synthesis, see:
-
1a
Wong HNC.Hon M.-Y.Tse C.-W.Yip Y.-C.Tanko J.Hudlicky T. Chem. Rev. 1989, 89: 165 -
1b
Danishefsky S. Acc. Chem. Res. 1979, 12: 66 -
1c
Brandi A.Cicchi S.Cordero FM.Goti A. Chem. Rev. 2003, 103: 1213 -
1d
Ichiyanagi T.Kuniyama S.Shimizu M.Fujisawa T. Chem. Lett. 1997, 1149 -
1e
Enholm EJ.Jia ZJ. J. Org. Chem. 1997, 62: 5248 -
1f
Enholm EJ.Jia ZJ. J. Org. Chem. 1997, 62: 9159 -
2a
Han Z.Uehira S.Tsuritani T.Shinokubo H.Oshima K. Tetrahedron 2001, 57: 987 -
2b
Yadav VK.Balamurugan R. Org. Lett. 2003, 5: 4281 ; and references cited therein - For other examples of the synthesis of 5-aryl-3,4-dihydro-2H-pyrrole, see:
-
5a
Stevens RV.Ellis MC.Wentland MP. J. Am. Chem. Soc. 1968, 90: 5576 ; and references cited therein -
5b
Stevens RV.Wentland MP. J. Am. Chem. Soc. 1968, 90: 5580 -
5c
Keely SL.Tahk FC. J. Am. Chem. Soc. 1968, 90: 5584
References
In the presence of catalytic amount of Zr(OTf)4, a prolonged reaction time was required. During a prolonged reaction time, this reaction accompanied the cyclized product 5. In order to accelerate the reaction rate and let the reaction complete within a short time to give the ring-opened compound 3 as a major product, Zr(OTf)4 (100 mol%) was employed.
4A variety of Lewis acids and solvent have been tested in this reaction (unpublished results from our laboratory). As a result of these investigations, we found that Zr(OTf)4 is the best Lewis acid for this reaction.