General Access to Allene-Containing Polymers Using the Skattebol Rearrangement

Postsynthetic modification is a powerful strategy for tuning soft materials. While methods for side-chain functionalization abound, modifications of backbone structural elements can be difficult to achieve. This challenge arises, in part, from a lack of intrinsically reactive motifs that can be installed in the main chain of a polymer. Incorporating established synthetic handles into polymer architectures is paramount for overcoming this limitation. Allenes are salient examples of moieties that could be leveraged in a wide range of postsynthetic modifications; however, the synthesis of a polyallene has proven elusive. Using the metathesis polymer of norbornene as a model architecture, we have established the Skattebol rearrangement as a facile route to polyallenes. Polymers with varying allene content (20-95%) were readily prepared in excellent yields (89-94%). These materials possess unique optical properties and can be engaged through further postsynthetic modifications. As such, polyallenes could serve as valuable platforms for developing functional soft materials.