The present invention for producing the EXP-3174 of formula (1) of using a method for producing a Rosa main metabolite potassium salt (see formula 2) of EXP-3174, known as the Tan in ultrapure and this ultra high purity? 2H ₂ O It relates to a method. Manufacturing method according to the present invention is to produce a compound of formula (3) to a deprotection reaction of a compound of formula 4 (a); (b) to produce a crude (crude) EXP-3174? 2H ₂ O compound having the structure of formula (1) of the dihydrate form then optionally oxidized to aldehyde using an oxidizing agent and the resulting compound from step (a) step; (C) step of having the compound having the structure of formula 1 is heated to reflux in a mixed solvent of water and ethyl acetate then filtered from the cooling step (b); (D) to obtain the compound of Formula 2 to the mixed solvent of the filtered product from the step (c) of isopropyl alcohol (IPA) and the protonic polar solvent to form a salt with KOH; And (e) was neutralized in a mixed solvent of water and ethyl acetate under the above step (d) an acidic condition a compound of formula 2 from performing a process of the above step (c). According to the present invention, the potassium salt, and EXP-3174? 2H ₂ O of EXP-3174 is prepared as a second high purity content of a single flexible material that does not exceed 0.1%.