Synthesis of 4,5-dihydro-1H-imidazole-4-carboxylates from α-amino acid amidines

Various β-hydroxy-substituted amidines were obtained starting from methyl serinates, aldehydes or ketones, and tosyl azide. These were converted via Mitsunobu intramolecular cyclization into enantiomerically pure methyl 2-alkyl-l-tosyl-4,5-dihydro-1H-imidazole-4-carboxylates.