A Synthesis of Tamiflu by Using a Barium‐Catalyzed Asymmetric Diels–Alder‐Type Reaction

In pursuit of a better route: A new catalytic asymmetric synthesis of Tamiflu was developed. The key transformation was an asymmetric Diels–Alder-type reaction of 1 and 2 catalyzed by a barium/F2-FujiCAPO complex in the presence of a CsF co-catalyst to construct the core of Tamiflu (see scheme; TMS=trimethylsilyl). The product was converted into Tamiflu in 11 steps on a gram scale.