adding triethyl amine would do it

Hi Ullah, I suggest you try to use L-Lysine methyl ester as your nucleophile. You can purchase it or prepare it from lysine and HCl in MeOH.

If you prepare it and isolate it as HCl salt, add excess DIPEA or TEA into your reaction to free the amine group. Once you isolate the product of Michael addition, you can hydrolise the ester to free the carboxylic group if required.

Ensure that the reaction pH is high enough to suppress the zwitterion formation. > than the pka of L-Lysine so ~ pH10.

adding triethyl amine would do it

thanks to all of you for your attention and useful answer. I am sure your suggestion will solve my problem.