Synthesis 2012; 44(8): 1213-1218
DOI: 10.1055/s-0031-1289738
paper
© Georg Thieme Verlag Stuttgart · New York

Iron(III)-Catalyzed Nucleophilic Substitution of the Hydroxy Group in Benzoin by Alcohols

Anvar Mirzaei
a   Islamic Azad University Sanandaj Branch, Department Of Chemistry, Kurdistan, Iran
,
Srijit Biswas
b   Department of Biochemistry and Organic Chemistry, Box 576, 751 23 Uppsala University, Sweden, Fax: +46(18)4713818   Email: joseph.samec@biorg.uu.se
,
Joseph S. M. Samec*
b   Department of Biochemistry and Organic Chemistry, Box 576, 751 23 Uppsala University, Sweden, Fax: +46(18)4713818   Email: joseph.samec@biorg.uu.se
› Author Affiliations
Further Information

Publication History

Received: 04 October 2011

Accepted after revision: 15 February 2012

Publication Date:
27 March 2012 (online)


Abstract

The etherification reaction between benzoin derivatives and alcohols catalyzed by iron(III) proceeds in moderate to good yields. Other metal complexes showed either low reactivity or low chemoselectivity where oxidation of benzoin to benzil was a competing reaction. The iron source operated as a catalyst where 5 mol% of iron(III) generate the 2-alkoxy-1,2-diphenylethan-1-one in 50% yield. With an optimum of 25 mol% of catalyst, the desired ether was obtained in 85% yield. The etherification of benzoin and an alcohol proceed to generate the desired product in polar solvents such as 1,2-dichloroethane, whereas less polar solvents promote the competing oxidation to generate the benzil; polar coordinating solvents such as tetrahydrofuran inhibited the reaction. The efficiency of the reaction is found to be dependent on nucleophile where an optimum of 30 equivalents of alcohol was observed. With electron-­donating substituents on the aromatic ring, the etherification was followed by oxidation to generate the benzil. Moderate yields of etherification product were obtained by monitoring the reaction progress with electron-rich substrates and quenching the reaction after two hours.

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