In this communication we wish to report on the synthesis of PBFxSy copolyesters by ring opening polymerization (ROP) using either organometallic catalysts or enzymes. The ROP of macrocyclic oligomers (MCOs) has been demonstrated to offer significant advantages over the traditional polycondensation method. The synthesis of MCOs of butylene succinate c(BS)n is known from long whereas MCOs of butylene 2,5-furandicarboxylate (c(BF)n) have not been reported until very recently. In this work, the synthesis of c(BF)n and c(BS)n has been performed using high dilution condensation (HDC) and enzymatic cyclization, respectively. Mixtures of dimer to tetramer and dimer to nonamer were obtained for c(BF)n and c(BS)n respectively.