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Synlett 2006(4): 0642-0644  
DOI: 10.1055/s-2006-932464
LETTER
© Georg Thieme Verlag Stuttgart · New York

Mercuric Triflate Catalyzed Cycloisomerization of Alkynyl-1,3-Cyclo­hexanedione and Alkynyl-1,3-Cyclopentanedione

Hiroshi Imagawa, Shuhei Kotani, Mugio Nishizawa*
Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan
Fax: +81(88)6553051; e-Mail: mugi@ph.bunri-u.ac.jp;
Further Information

Publication History

Received 24 December 2005
Publication Date:
20 February 2006 (online)

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Abstract

Mercuric triflate was used to catalyze cycloisomerization of alkynyl-1,3-cyclohexanediones and cyclopentanediones to give fused oxabicyclic systems under mild reaction conditions with high catalytic turnover up to 1000 times.

Key words

mercuric triflate - catalytic cycloisomerization - alkyn­yl-1,3-cyclohexanediones

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Typical Experimental Procedure.
Tetramethylurea (1.15 mg, 0.0099 mmol) and a stock solution of Hg(OTf)2 in MeCN (0.01 M solution, 330 µL, 0.0033 mmol) were added to a solution of alkynyldione 1 (50 mg, 0.333 mmol) in MeCN (3.3 mL, 0.1 M) at r.t. The solution was stirred for 30 min at r.t., and aq NaHCO3 was added. The mixture was extracted with CH2Cl2 and dried. Concentrated extract was subjected to a column chromatography on silica gel (hexane-EtOAc, 6:1) to give exclusively the oxabicyclic product 2 (50 mg, 0.333 mmol).