Purification Methods
1,4-Benzodioxane-2-carboxylic Acid has two isomeric forms, (S) and (R), which can be separated by crystalline salts. The diastereomeric N-1-phenylethylamides of (S)- and (R)-1,4-benzodioxane-2-carboxylic Acid differ significantly in melting and solubility, and can therefore be efficiently discriminated by precipitation of the less soluble diastereoisomers (>98%de), whereas chromatographic purification of the unprecipitated portion results in the soluble diastereoisomers (>99%de). Overall, recoveries were 95% for the former and 80% for the latter. Hydrolysis of the two catabolic amides gave the two acid enantiomers and the catabolic amine in quantitative yields with no change in stereoisomer purity.
