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Paper | Regular issue | Vol 63, No. 3, 2004, pp.519-527
Published online, 9th January, 2004
DOI: 10.3987/COM-03-9947
Synthesis and Spectroscopic Differentiation of 2- and 4-Alkoxythiotetronic Acids

Gautham Shenoy, Pilho Kim, Michael Goodwin, Quynh-Anh Nguyen, Clifton E. Barry, 3rd, and Cynthia S. Dowd*

*Tuberculosis Research Section, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852, U.S.A.


O-Alkylation of thiotetronic acids gives a mixture of 2- and 4-position enol ether products. Comparison of the physical data revealed that UV spectroscopy was the most reliable method of distinguishing between these related ethers. We have determined that 4-position ethers have a distinct absorption between 235-240 nm, while 2-position ethers have two absorbance peaks, one between 205-220 nm and the other between 305-310 nm. This report describes the synthesis and unambiguous characterization of 2- and 4-methoxy-3,5-dimethylthiotetronic acids. The UV absorption properties of several other pairs of thiotetronic acid ethers confirm that these differences are general features that provide a simple method for distinguishing between 2- and 4-substituted isomers.