Catalyst-Free Thiol-yne Nucleophilic Photoclick Chemistry.

X-yne nucleophilic addition reactions are essential and powerful tools in a range of synthetic routes for realizing functional and stimuli-responsive materials. Unfortunately, the lack of spatiotemporal control and the requirement for catalyst addition in these reactions limit their full potential in synthetic and materials-based applications, including in light-driven 3D printing. Herein, we close this critical gap and exploit a spirothiopyran (STP) photoswitch as a synthon for photoinduced and catalyst-free thiol-yne click reactions, an important class of X-yne click chemistries. We further employ our photoswitch-based entity for rapid and facile postpolymerization modification as well as photopolymerization under very mild and aerobic conditions.