Partial Hydrolysis of 1. An aqueous solution (1 mL) of 1 (1 mg) was heated in a boiling water bath for 1 h. The reaction mixture was analyzed by normal- and reversed-phase HPLC (solvent B) to show the peaks due to 2,3,6-tri-O-galloyl-D- glucose (14) and rugosin A (15).