Synthesis of (–)‐Oseltamivir by Using a Microreactor in the Curtius Rearrangement

A microflow reaction of the Curtius rearrangement by using trimethylsilyl azide as an azide source, followed by trapping of the generated isocyanate with a nucleophile was established, which is safe, inexpensive, and suitable for large‐scale synthesis. By this flow reaction in the Curtius rearrangement and recrystallization of the late‐stage acetamide intermediate the third‐generation synthesis of (–)‐Oseltamivir has been established, which is efficient, practical, and safe.