Efficient Preparation of the Key Intermediate in Corey's Tamiflu Synthesis

A very efficient two-step synthesis was developed to prepare the key intermediate in Corey's Tamiflu synthesis. DBU (1,8-diazabicyclo[5.4.0] undec-7-ene) was used as a multifunctional catalyst for a series of reactions in a one pot procedure. The new synthesis was featured by the good availability of the starting material and the ease of the synthetic steps. This method might be practical for large scale preparations.