A tube ride: The controlled chemical synthesis of uniform, single‐walled carbon nanotubes from short hydrocarbon templates, such as aromatic belts and geodesic nanotube end‐caps, by a Diels–Alder cycloaddition/rearomatization strategy requires a potent “masked acetylene” capable of transforming hydrocarbon bay regions into new unsubstituted benzene rings in a single operation. Nitroethylene has been found to effect such benzannulations (see scheme).