Total synthesis of A-315675: a potent inhibitor of influenza neuraminidase

A concise, stereocontrolled, and practical synthesis of a neuraminidase inhibitor consisting of a highly functionalized D-proline scaffold is described. Key features involve a stereocontrolled addition of a propiolate ester to a chiral nonracemic nitrone derived originally from D-serine and the manipulation of acyclic and cyclic motifs en route to the target in 12.8% overall yield over 22 steps. Several crystalline intermediates were suitable for single-crystal X-ray analysis.