Metacaspase is an enzyme involved in the cell death of fungi, protozoa, and plants. It is absent in humans and distinctively different from the orthologous human caspases. Inhibitors of this enzyme may be useful as antiparasitics by modulating the activity of the enzyme. In the research conducted by Berg, an inhibitor of a related metacaspase found in the organism Trypanosoma brucei was synthesized. The inhibitor is an alpha-keto heterocycle derived from arginine and benzothiazole. Berg’s synthetic approach lacked flexibility and resulted in low yields. To overcome these limitations, we took inspiration from the Grignard synthetic approach by Demkiw to generate alpha-keto heterocycles in a single step with good yields. This approach allows for the generation of a library of alpha-keto heterocyclic peptidomimetics as potential inhibitors for S. commune metacaspase. The stereoselectivity of this approach was assessed by high performance liquid chromatography.