Elemental tellurium is a useful and recoverable reagent in nucleophilic reductions by telluride ion which involves attack by the strongly nucleophilic  anion at an electrophilic site in certain organic compounds which triggers a formal reduction of the compound with concomitant formation of elemental tellurium: This nucleophilic reduction process is applied to the synthesis of tetramic and tetronic acids and their derivatives starting with amino acids or hydroxycarboxylic acids.