SYNTHESIS AND SPECTROSCOPIC DIFFERENTIATION OF 2- AND 4-ALKOXYTHIOTETRONIC ACIDS.

Abhijit A Patil, Parag Sayal, Marie-Lise Depondt, Ryan D Beveridge, Anthony Roylance, Deepti H Kriplani, Katie N Myers, Angela Cox, David Jellinek, Malee Fernando, Thomas A Carroll, Spencer J Collis

Index: Heterocycles 63 , 5-8, (2004)

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Abstract

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.