SYNTHESIS AND SPECTROSCOPIC DIFFERENTIATION OF 2- AND 4-ALKOXYTHIOTETRONIC ACIDS.
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.
Shenoy
Gautham
G
Tuberculosis Research Section, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852 USA; Email: cdowd@niaid.nih.gov.
Kim
Pilho
P
Goodwin
Michael
M
Nguyen
Quynh-Anh
QA
Barry
Clifton E
CE
Dowd
Cynthia S
CS