Synthesis, absolute configuration, and circular dichroism of the enantiomers of fluorosuccinic acid

Abstract

Diethylaminosulphur trifluoride (DAST) converts (2S)- and (2R)-malate esters into the enantiomeric fluorosuccinate esters. (2S,3R)-[3-²H₁]Malate, obtained from fumarate by fumarase-catalysed hydration in deuterium oxide, was used to show that the reaction with DAST occurs stereospecifically with inversion of configuration. Conversion of (2S)-aspartic acid into fluorosuccinate with sodium nitrite in polyhydrogen fluoride-pyridine occurs predominantly with retention of configuration. The circular dichroic spectra of (2S)- and (2R)-fluorosuccinic acids and their methyl esters are‘anomalous’ and consequently the absolute configuration previously assigned to a Pseudomonal metabolite, (+)-fluorosuccinic acid, is shown to be erroneous.