Double elimination protocol for convenient synthesis of dihalodiphenylacetylenes: Versatile building blocks for tailor-made phenylene-ethynylenes

Dihalodiphenylacetylenes are conveniently synthesized by a double elimination reaction of beta-substituted sulfones which are readily obtained from halogen-substituted benzyl sulfone and benzaldehyde derivatives. Halogens can be incorporated at any desired positions in the diphenylacetylene skeleton simply by choosing the substitution position of the halogen on the aromatic rings of the starting compounds. The diphenylacetylenes with different halogen substituents thus obtained undergo sequential carbon-carbon bond formations due to the different reactivities of the halogens. Thus, various moieties can be incorporated on the diphenylacetylene skeleton at whichever positions so that a variety of tailor-made phenylene-ethynylenes with regulated structure and composition could be designed.