De Novo Synthesis of Tamiflu via a Catalytic Asymmetric Ring-Opening of <i>meso</i>-Aziridines with TMSN<sub>3</sub>

An asymmetric ring-opening reaction of <i>meso</i>-aziridines with TMSN<sub>3</sub> was developed using a catalyst prepared from Y(O<i><sup>i</sup></i><sup></sup>Pr)<sub>3</sub> and chiral ligand <b>2</b> in a 1:2 ratio. Excellent enantioselectivity was realized from a wide range of substrates with a practical catalyst loading. The products were efficiently converted to enantiomerically enriched 1,2-diamines, which are versatile chiral building blocks for pharmaceuticals and chiral ligands. This reaction was applied to a catalytic asymmetric synthesis of Tamiflu, a very important anti-influenza drug containing a chiral 1,2-diamino functionality.