Ring-opening polymerization that involves β-alkyl elimination can be catalyzed by Ti, Zr, Pd-based catalyst, and some Lanthanide-based metallocene catalyst, where different polymerization patterns vary when catalysts are different. Examples of copolymerization with alkene  or carbon monoxide were also reported. The key step of this kind of ROP is string-driven β-alkyl elimination, which provides linear polymer with unsaturation in the polymer chain.