Vinyl-aza-[3]cumulene intermediates induced polymerization for accessing E-dienyl poly(sulfonylamidines) towards pH-responsive drug delivery.

The development of reactive intermediates is very significant to construct functional compounds and polymers for multicomponent reactions and multicomponent polymerizations. Heterocumulenes as unique intermediates could be used for the rapid construction of diverse structural skeletons. In this work, a copper-catalyzed multicomponent reaction and polymerization of yne-allylic esters, amines, and azides was disclosed involving so-far unrecognized vinyl alkylidene ketenimine intermediates. Various poly(dienyl-N-sulfonylamidines) were excellently regio- (α-addition) and stereoselectively (E-exclusive) synthesized with molecular weights (7800-26,700 g/mol) and good thermal and chemical stability. Based on the self-assembly of polymers into nanoparticles in water, doxorubicin-loaded nanoparticles (DOX-NPs) were successfully prepared for drug delivery. The drug release results revealed that the DOX-NPs owned sensitive pH-responsive characteristics.