3-Deoxy-D-arabino-heptulosonic acid 7-phosphate (DAHP) is a 7-carbon ulonic acid. This compound is found in the shikimic acid biosynthesis pathway and is an intermediate in the production of aromatic amino acids. Phosphoenolpyruvate and erythrose-4-phosphate react to form 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP), in a reaction catalyzed by the enzyme DAHP synthase. The mechanism of ring closure is complex, but involves an aldol condensation at C-2 and C-7.