Subscribe to RSS
DOI: 10.1055/s-2006-947363
Bu4N[AuCl4]-Catalyzed Synthesis of Highly Substituted Furans from 2-(1-Alkynyl)-2-alken-1-ones in Ionic Liquids: An Air-Stable and Recyclable Catalytic System
Publication History
Publication Date:
24 July 2006 (online)
Abstract
The cyclization of 2-(1-alkynyl)-2-alken-1-ones proceeded smoothly in the presence of various nucleophiles with a catalytic amount of Bu4N[AuCl4] in [bmim]BF4, leading to the formation of highly substituted furans. This system is air-stable and recyclable. The catalyst is inexpensive and readily available.
Key words
gold-catalyzed - cyclization reaction - ionic liquids - furans - recyclable
- 1
Maier M. Organic Synthesis Highlights IIWaldmann H. VCH; Weinheim: 1995. p.231 - 2
Donnelly DMX.Meegan MJ. Comprehensive Heterocyclic Chemistry Vol. 4:Katritzky AR.Rees CW. Pergamon; New York: 1984. p.657 - Recent reviews:
-
3a
Hou XL.Yang Z.Wong HNC. Progress in Heterocyclic Chemistry Vol. 14:Gribble GW.Gilchrist TL. Pergamon Press; Oxford: 2002. p.139-179 -
3b
Hou XL.Chueng HY.Hong TY.Kwan PL.Lo TH.Tong SY.Wong HNC. Tetrahedron 1998, 54: 1955 -
3c
Cacchi S. J. Organomet. Chem. 1999, 576: 42 -
3d
Keay BA. Chem. Soc. Rev. 1999, 28: 209 -
3e
Lipshutz BH. Chem. Rev. 1986, 86: 795 -
4a
Sheng H.Lin S.Huang Y. Tetrahedron Lett. 1986, 27: 4893 -
4b
Fukuda Y.Shiragami H.Utimoto K.Nozaki H. J. Org. Chem. 1991, 56: 5816 -
4c
Kel’in AV.Gevorgyan V. J. Org. Chem. 2002, 67: 95 -
4d
Ma S.Zhang J. Chem. Commun. 2000, 117 -
4e
Ma S.Zhang J.Lu L. Chem. Eur. J. 2003, 9: 2447 -
4f
Hashmi ASK.Schwarz L.Choi J.-H.Frost TM. Angew. Chem. Int. Ed. 2000, 39: 2285 -
4g
Marshall JA.Wang X.-J. J. Org. Chem. 1991, 56: 960 -
4h
Marshall JA.Wang X.-J. J. Org. Chem. 1992, 57: 3387 -
4i
Marshall JA.Bartley GS. J. Org. Chem. 1994, 59: 7169 -
4j
Arcadi A.Cacchi S.Larock RC.Marinelli F. Tetrahedron Lett. 1993, 34: 2813 -
4k For a recent review, see:
Brown RCD. Angew. Chem. Int. Ed. 2005, 44: 850 -
5a
Lo CY.Guo H.Lian JJ.Shen FM.Liu RS. J. Org. Chem. 2002, 67: 3930 -
5b
Marshall JA.DuBay WJ. J. Am. Chem. Soc. 1992, 114: 1450 -
5c
Hashmi ASK.Sinha P. Adv. Synth. Catal. 2004, 346: 432 -
6a
Gabriele B.Salerno G.Lauria E. J. Org. Chem. 1999, 64: 7687 -
6b
Seiller B.Bruneau C.Dixneuf PH. J. Chem. Soc., Chem. Commun. 1994, 493 -
6c
Liu Y.Song F.Song Z.Liu M.Yan B. Org. Lett. 2005, 7: 5409 - 7
Bew SP.Knight DW. Chem. Commun. 1996, 1007 -
8a
Yao T.Zhang X.Larock RC. J. Am. Chem. Soc. 2004, 126: 11164 -
8b
Suhre MH.Reif M.Kirsch SF. Org. Lett. 2005, 7: 3925 -
8c For a review of gold catalysis, see:
Hashmi ASK. Gold Bull. 2004, 37: 51 - 9
Patil NT.Wu H.Yamamoto Y. J. Org. Chem. 2005, 70: 4531 - For the synthesis of furans by the electrophilic cyclization of the same substrate, see:
-
10a
Yao T.Zhang X.Larock RC. J. Org. Chem. 2005, 70: 7679 -
10b
Liu Y.Zhou S. Org. Lett. 2005, 7: 4609
References and Notes
Representative Procedure.
To the appropriate 2-(1-alkynyl)-2-alken-1-one (0.2 mmol) and nucleophile (1.5 equiv) in [bmim]BF4 (1 mL) was added Bu4N[AuCl4] (1 mol%). The mixture was stirred at r.t. for 3 h unless otherwise specified. The mixture was extracted with Et2O (2 ¥ 5 mL). The isolated ether layer was concentrated in vacuo and the residue was purified by flash chromatography on silica gel.
Recycling Procedure.
To the 2-phenylethynyl-2-cyclohexen-1-one (1.0 mmol) and MeOH (1.5 equiv) in [bmim]BF4 (3 mL) was added Bu4N[AuCl4] (1 mol%). The mixture was stirred at r.t. for 3 h. The product was extracted from the reaction mixture by addition of Et2O (2 ¥ 20 mL). The ether layer was separated. The ionic liquid layer containing Au catalyst was pumped for several minutes and reused for the next reaction.
Spectral Data of the Representative Product 2a.
1H NMR (300 MHz, CDCl3): δ = 1.79-1.93 (m, 2 H), 1.94-2.05 (m, 2 H), 2.59-2.75 (m, 2 H), 3.43 (s, 3 H), 4.28 (t, J = 3.9 Hz, 1 H), 6.64 (s, 1 H), 7.18-7.23 (m, 1 H), 7.31-7.36 (m, 2 H), 7.60-7.63 (m, 2 H). 13C NMR (75 MHz, CDCl3): δ = 18.8, 23.2, 28.3, 56.1, 72.3, 105.3, 119.9, 123.3, 126.8, 128.5, 131.1, 152.2, 152.8.