Synlett 2005(8): 1316-1318  
DOI: 10.1055/s-2005-865224
LETTER
© Georg Thieme Verlag Stuttgart · New York

Stereo- and Regioselective Zinc-Mediated Ring-Opening of Epoxides with Diselenides

Barahman Movassagh*, Mojgan Shamsipoor
Department of Chemistry, K. N. Toosi University of Technology, P. O. Box 15875-4416, Tehran, Iran
Fax: +98(21)2853650; e-Mail: bmovass1178@yahoo.com;
Further Information

Publication History

Received 6 January 2005
Publication Date:
21 April 2005 (online)

Abstract

Two convenient rapid, efficient, stereoselective and highly regioselective methods for the synthesis of β-hydroxy selenides by the direct opening of epoxides with diselenides in acetonitrile in the presence of either Zn/AlCl3 or zinc powder in aqueous sodium hydroxide solution are described. These methods appear to be competitive with the other methods previously reported.

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General Experimental Procedure: Method A.
A stirred solution of the diselenide (0.5 mmol) in anhydrous MeCN (15 mL) was treated with activated zinc powder (2.5 mmol). The mixture was refluxed for 1.5 h, during which time the zinc powder was almost completely consumed. Then, finely ground anhydrous AlCl3 (1.2 mmol) and the epoxide (1.5 mmol) were added to the solution and stirring was continued for the specified time (Table [1] ) without protection from the atmosphere. Progress of the reaction was monitored by TLC. After completion of the reaction, the solvent was evaporated and the residue was acidified to pH 4 with HCl (10%). The organic phase was extracted with Et2O (2 × 15 mL), dried (Na2SO4), and concentrated. The pure products were obtained by preparative TLC (silica gel, eluent, CCl4/Et2O = 2:1) to afford the desired β-hydroxy selenides.

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General Experimental Procedure: Method B. A mixture of diselenide (0.5 mmol) and activated zinc powder (2.5 mmol) was suspended in MeCN (15 mL). The mixture was refluxed, with stirring, for 10 min. To this mixture was added 25% NaOH (3 mL, 18.8 mmol), and the mixture was stirred for further 5 min, during which time the yellow solution turned to colorless. Then, the epoxide (1 mmol) was added in one portion to the solution and stirring was continued for the length of time indicated in Table [1] . When the reaction was complete, the organic solvent was evaporated, and the residue was acidified to pH 4 with HCl (10%). The organic layer was extracted with Et2O (2 × 20 mL), dried (Na2SO4), and evaporated. Preparative TLC yielded the pure products.