Copper-Catalyzed Electrophilic Polyhydroamination of Internal Alkynes

Polyhydroamination of alkynes is an important methodology for preparing nitrogen-containing polymers. At present, all of the reported polyhydroamination of alkynes proceed through nucleophilic addition, and no straightforward electrophilic polyhydroamination has been reported. In this paper, a novel copper-catalyzed electrophilic polyhydroamination of alkynes was developed, and soluble and thermally stable poly(enamine)s with high weight-average molecular weights (Mws, up to 12 650) were produced in excellent yields (up to 95%) under mild reaction conditions. Moreover, the regioselectivity of this electrophilic polyhydroamination could be tuned by adjusting one of the substitutions of internal diynes from phenyl to alkyl group. By introducing the tetraphenylethene moiety into polymer backbones, the resultant polymers exhibit unique aggregation-induced emission feature, and their aggregates could be used to sensitively detect explosives. This efficient polymerization will open up enormous opportunities for preparing functional nitrogen-containing acetylenic polymers applicable in diverse areas.