Industrially Viable Alternative to the Friedel−Crafts Acylation Reaction: Tamoxifen Case Study

A mixed anhydride, formed in situ by reaction of trifluoroacetic anhydride and an alkanoic acid, has been successfully used as an acylating agent in an industrially based synthesis of Tamoxifen. This acylation process has a number of advantages over the classic Friedel−Crafts route. Thus the use of thionyl chloride, aluminium trichloride, and a chlorinated hydrocarbon solvent are all eliminated. The trifluoroacetic anhydride is recovered from the reaction system as trifluoroacetic acid, which can be efficiently converted back to the anhydride using phosphorus pentoxide. The general applicability of this acylation process is discussed.