Glyoxylic Acid → Acetic Anhydride

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Intermediate 2, (3-ethoxy-4-hydroxyphenyl)hydroxy-acetic acid can be prepared by addition of base to an aqueous mixture of 2-ethoxyphenol and glyoxylic acid cooled to 0° C. Intermediate 3, acetoxy-(4-acetoxy-3-ethoxyphenyl)-acetic acid, can be formed by the addition of acetic anhydride to intermediate 2 dissolved in dichloromethane (DCM) and pyridine, cooled in an ice bath. Intermediate 3 dissolved in a short chain alcohol is reduced under hydrogen to provide intermediate 4, (4-acetoxy-3-ethoxyphenyl)-acetic acid, which is reacted with an excess of propanol and a catalytic amount of concentrated H2SO4 to form the propyl ester, intermediate 5, (3-ethoxy-4-hydroxyphenyl)-acetic acid propyl ester. Finally, intermediate 5 is reacted with a compound of the structure X—CH2C(═O)N(Et)2, where X is a leaving group, in the presence of potassium carbonate to provide the active agent, compound 1.

Herkunft & Nachweise