合成路线1

This compound can be obtained in three similar ways: 1) The reaction of N-acetyl-L-methionine (I) with ethyl chloroformate (II) and triethylamine in chloroform gives the corresponding mixed anhydride (III), which is then condensed with 3,4-di(ethoxycarbonyloxy)phenethylamine tosylate (IV) by means of triethylamine in chloroform. 2) The reaction of N-acetyl-L-methionine (I) with N-hydroxysuccinimide (V) by means of dicyclohexylcarbodiimide (DDC) in dioxane gives the corresponding active ester (VI), which is then condensed with the amine (IV) as before. The active ester method can also be carried out in this case using N-hydroxyphthalimide, 1-hydroxybenzothiazole or 4-nitrophenol instead of N-hydroxysuccinimide (V). 3) The reaction of the active ester (VI) with dopamine (VII) by means of triethylamine in DMF gives the corresponding amide (VIII), which is then acylated with ethyl chloroformate (IX) in pyridine.