The present disclosure provides processes for the preparation of unsaturated polyesters. In embodiments, a process of the present disclosure includes reacting an organic diol with a cyclic alkylene carbonate in the presence of a first catalyst to thereby form a polyalkoxy diol, optionally adding thereto a further amount of cyclic alkylene carbonate in the presence of a second catalyst, and subsequently polycondensing the resulting mixture with a dicarboxylic acid in combination with an anhydride.