A Synthetic Entry to Amino Acid Derivatives through Davidson-like Heterocyclization

The modification of amino acids leads to valuable building blocks for the synthesis of bioactive compounds. By keeping the amino group protected, the carboxylic acid functionality can be converted in two steps to an imidazole moiety via a Davidson-like heterocyclization. This reaction allows for a combinatorial approach, in which two positions at the heterocycle can be modified. Herein, we report on the synthesis of such imidazole derivatives by using N-protected cyclohexylalanine as the starting material, which was subjected to Davidson-like heterocyclization. By using different α-haloketones, two points of diversity were examined, position 4 and 5, respectively. The building blocks can serve as the starting point for the synthesis of bioactive peptides to be provided to pharmacological studies.