Poly( <i>O</i> ‐Propargyl‐ <i>N</i> ‐Amino Carbamate), a Reactive Polymer to Underpin Biomedical Applications of Poly(acetylene)s

Synthetic polymers are widely used in biomedical applications, yet most lack defined secondary structures common in nature, such as helices or β-sheets. In particular, dynamic helical polymers such as poly(acetylene)s have been rarely explored in this field. Here, we report the preparation of a new reactive poly(acetylene), poly(O-propargyl-N-amino carbamate) (P1), as a platform for the preparation of functional poly(acetylene)s in water. P1 was prepared from readily available starting materials through Rh-catalyzed polymerization and acid-mediated deprotection. ¹H-NMR indicated that the formed polymer had a high content of cis double bonds, while UV-vis and DSC suggested a predominant cis-cisoid conformation. This conformation was also observed via CD for chiral derivatives of Boc-protected P1, while a partially deprotected chiral derivative of P1 could be adopting multiple conformations in solution, including cis-transoid and cis-cisoid conformations. P1 was functionalized under aqueous conditions with a small set of aldehydes, including cationic, aliphatic, and aromatic derivatives, as well as a small set of carbohydrates. Finally, we demonstrate that P1, and a guanidinium derivative P1-mod-4, were well tolerated by cells, highlighting the potential of this polymer to underpin the development of biomedical applications of poly(acetylene)s.