Pd-Catalyzed MIA-Directed Methoxylation of Phenylalanines: A Combined Experimental and Computational Study

The direct methoxylation of substituted phenylalanines has been accomplished via methoxyiminoacyl (MIA)-mediated Pd-catalyzed C-H functionalization. A diverse array of ortho-methoxylated phenylalanine derivatives are efficiently generated in good to high yields. KIE study has shown that the oxhydryl cleavage step is the rate-limiting step. The computational data show that the participation manner of methanol has a great influence on the energy barriers of transition states during the C(sp2)-O formation stage. The pathway containing stepwise deprotonation and reductive elimination is superior to that of a concerted deprotonation-methoxylation.

Automated summary

The direct methoxylation of substituted phenylalanines has been achieved through methoxyiminoacyl (MIA)-mediated Pd-catalyzed C-H functionalization, resulting in the efficient synthesis of diverse ortho-methoxylated phenylalanine derivatives in good to high yields. Kinetic isotope effect studies reveal that the oxhydryl cleavage step is the rate-limiting step. Computational data demonstrate that the manner in which methanol participates greatly influences the energy barriers of transition states during the C(sp2)-O formation stage, with stepwise deprotonation and reductive elimination being superior to concerted deprotonation-methoxylation.