Plasticizers: Synthesis of phthalate esters via FeCl3-catalyzed nucleophilic addition of alcohols to phthalic anhydride

Phthalates are esters of phthalic anhydride. Phthalic anhydride (1) has been reacted with alcohols 2 to synthesize phthalate monoesters 3 and diesters 4 with the favor of latter compound that primarily used as plasticizers worldwide. This two-steps process operates in single pot, in the presence of 10 mol% of FeCl3 as a catalyst. Mechanistically, the first step is the formation of phthalate monoesters 3 that involves a facile addition-displacement pathway, and the second step is essentially underwent a Lewis acid catalysis providing phthalate diesters 4 with very good yields. Application of the present reaction is demonstrated by synthesizing a macrolide 5 through the ring-closing metathesis of diallyl phthalate (4b) using the Grubb’s 2nd generation catalyst.