Synthesis of macrocyclic α-ketoamide as a selective and reversible immunoproteasome inhibitor

In recent years, the human immunoproteasome has emerged as an attractive therapeutic target for various diseases, leading to a growing interest in the discovery of immunoproteasome inhibitors that selectively target specific subunits. Herein we report the design, synthesis, and evaluation of a new immunoproteasome inhibitor that feature a macrocyclic ring containing an internal α-ketoamide warhead. This compound is a selective and reversible inhibitor of immunoproteasome subunits β1i and β5i and shows essentially no inhibition of constitutive proteasome subunits. [Figure not available: see fulltext.]