“Two Functional Groups in One Package”: Using Both Alkyne π-Bonds in Cascade Transformations

Spatial orthogonality of the two independently addressable π-systems in alkynes can be used for the design and control of metal-free cascade transformations. Examples include ionic chemistry of neutral hydrocarbons, preparation of radicals without radical initiators, generation of excited states without light, "1,2-dicarbene reactivity" of alkynes in "boomerang" radical processes, selective conversion of alkynes into carbonyl compounds, and full disassembly of the alkyne moiety.