Aziridine termination of living anionic polymerization

A switch from carbanions to aza-anions is performed by the addition of N-tosylaziridine (TAz) to living poly(styryl) (PS) chains. This is the first example of carbanionic aziridine ring-opening which was previously activated by amidation with a tosyl group to enable nucleophilic ring-opening by the living chain end. Poly(styrene)-tosylaziridines (PS-TAz) with narrow molecular weight distributions and variable molecular weights are synthesized. The removal of the tosyl group and subsequent functionalization is shown, evidencing quantitative transfer to azaanionic species. All polymers are characterized in detail by ¹H NMR spectroscopy, DOSY ¹H NMR spectroscopy, and size exclusion chromatography (SEC). This strategy allows the introduction of amine groups via anionic polymerization in analogy to the well-established epoxide termination. Aziridine-termination of living polymers was performed to quantitatively introduce amine functionalities at the polymer chain end in analogy to the well-established epoxide termination. The robust and easy protocol presents the first switch from carbanionic polymerization to living aza-anions by the addition of activated, i.e. tosylated aziridines which can be conveniently hydrolyzed to release the amines.