Streamlined process for the esterification and ketalization of shikimic acid en route to the key precursor for oseltamivir phosphate (Tamiflu (TM))

In an effort to streamline the current process for the key precursor en route to Tamiflu (TM) (oseltamivir phosphate), the ketalization reaction was re-evaluated for areas of improvement. Removal of thionyl chloride was a priority from a EH & S and operational perspective. Finally, the reduction of solvents and telescoping steps would improve throughput and minimize waste streams.