Chiral imidazole derivatives synthesis from enantiopure N-protected α-amino acids

A route to the preparation of enantiopure ligands based on a 2-phenylimidazol ring is described. The stereogenic centre is placed into the chain bonded to the fourth carbon of the imidazole ring. The synthesis starts from inexpensive and readily available N-protected α-amino acids, as the source of chirality, which are converted into appropriate α-diazoketones and, consequently, into α-bromoketones. These α-bromoketones are good precursors for reactions with amidines to provide the imidazole ring. The deprotection into the final products was carried out using hydrogen.