Synthesis and crystal structure of cis -4-azido-L-proline methyl ester hydrochloride

The key precursor for the synthesis of novel influenza neuraminidase inhibitors, cis-4-azido-L-proline methyl ester hydrochloride (C₆H₁₁ClN₄O₂, Mr = 206.63), was prepared as white needle-shaped crystals and its structure was elucidated by single-crystal X-ray diffraction. In the crystal structure, molecules are linked through intermolecular hydrogen bonds, forming layers perpendicular to the bc plane.