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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.