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Synlett 2011(5): 665-670  
DOI: 10.1055/s-0030-1259557
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Nucleophilic Substitution of Secondary Alkyl-Substituted Propargyl Acetates: An Economic and Practical Indium Trichloride Catalyzed Access

Min Lin, Lu Hao, Xiao-tao Liu, Qing-zhen Chen, Feng Wu, Ping Yan, Su-xia Xu, Xin-liang Chen, Jia-jie Wen, Zhuang-ping Zhan*
Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, P. R. of China
Fax: +86(592)2180318; e-Mail: zpzhan@xmu.edu.cn;
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Publication History

Received 25 December 2010
Publication Date:
11 February 2011 (online)

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Abstract

An economic and practical transformation from secondary alkyl-substituted propargyl acetates to a variety of nucleophilic substitution products was described. This reaction was catalyzed by inexpensive InCl3. High yields and excellent chemoselectivity were obtained. The five-, six-, and seven-membered propargyl cyclo­ethers were also successfully constructed by this protocol.

Key words

propargyl acetate - nucleophilic substitution - indium - propargyl cycloether

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General Procedure A for the Intermolecular Substitution Reactions between Alkyl-Substituted Propargyl Acetates and Nucleophiles To a 5 mL flask were successively added propargyl acetate (0.5 mmol, 1.0 equiv), nucleophile (1.5 mmol, 3.0 equiv), MeNO2 (2 mL) and anhyd InCl3 (6 mg, 0.025 mmol) at r.t. Then, the mixture was magnetically stirred at appropriate temperature until the reaction was completed as monitored by TLC. The reaction mixture was cooled down to r.t., and the solvent was removed under reduced pressure. Then the residue was purified by flash chromatography on silica gel to afford the substitution product.

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General Procedure B for the Intramolecular Substitution Reactions of Alkyl-Substituted Propargyl Acetates To a 5 mL flask were successively added propargyl acetate (1.0 mmol), MeNO2 (2 mL) and anhyd InCl3 (12 mg, 0.05 mmol) at r.t. Then, the mixture was magnetically stirred at 60 ˚C for 1 h. The reaction mixture was cooled down to r.t., and the solvent was removed under reduced pressure. The residue was purified by flash chromatography on silica gel to afford the intramolecular substitution product.