Process for condensing at least one epoxide on at least one cyclic anhydride in the presence of a catalyst based on titanium

The invention relates to a process for condensing at least one epoxide on at least one cyclic anhydride of a dicarboxylic acid in the presence of a catalyst consisting of at least one Peroxo-type titanium peroxide complex of the A-form. (CF DRAWING IN BOPI) This method makes it possible to obtain a perfectly alternating polyester.