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Synthesis 2006(5): 756-758  
DOI: 10.1055/s-2006-926338
SHORTPAPER
© Georg Thieme Verlag Stuttgart · New York

Sodium Amalgam: A Highly Efficient Reagent for the Detosylation of Azathiacrown Ethers

Philip B. Forshee, John W. Sibert*
Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75083, USA
Fax: +1(972)8832925; e-Mail: sibertj@utdallas.edu;
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Publication History

Received 17 July 2005
Publication Date:
07 February 2006 (online)

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Abstract

A simple, nearly quantitative method is demonstrated for the deprotection of tosylated mixed azathiacrown ethers using sodium amalgam. Four macrocycles, containing differing numbers of amino groups and ring sizes, were prepared using traditional cyclization procedures and the described deprotection technique. Three of the macrocycles, [12]aneNS3, [14]aneNS3, and [15]aneN2S3, were reported previously, though either in low yields, only in protected form, or using hazardous precursors, while the fourth, [18]aneN3S3, is a new ionophore.

Key words

supramolecular chemistry - crown compounds - macrocycles - ligands - reductions

14

In our procedure, the reaction was performed without external heat under an argon atmosphere with the reaction apparatus placed in an oil bath. After initiating the reaction by addition of a small amount of mercury to the sodium metal, the remaining mercury was immediately and quickly added (approx. 10-15 s total addition time) via an addition funnel with rapid stirring at room temperature. The amounts of reagents and reaction workup were as reported in ref. 15.