Resolution via diastereomeric amides of enantiopure 1,4‐benzoxathian‐2‐ and 3‐carboxylic acids and determination of their configuration

1,4‐Benzoxathiane, 2‐ or 3‐substituted, is an important scaffold, and despite its presence in several therapeutic agents, it is chemically unexploited. Furthermore, only a few examples in literature report this moiety in its enantiopure form. Here, taking advantage to the formation of diastereomeric amides by using (S)‐phenylethylamine, which show significant differences in terms of (1)H‐nuclear magnetic resonance (NMR) spectra and other physical chemical properties, we defined for the first time the absolute configuration of each amide, both 2‐ or 3‐substituted. Moreover, the diastereomeric amides were further hydrolyzed in acid conditions, letting to the achievement of the corresponding 1,4‐benzoxathian carboxylic acids.