Syntheses and properties of donor/acceptor arylethynyl-substituted 1,6-methano[10]annulenes

The stepwise palladium-catalyzed coupling of dibromo-1,6-methano[10]annulene derivatives to a phenylacetylene substituted by an electron-withdrawing group followed by coupling with a phenylacetylene possessing an electron-donating group allows the preparation of donor/acceptor systems which contain three aromatic moieties linked by ethynediyl bridges. The same type of cross-coupling starting from 2-ethynyl-1,6-methano[10]annulene and bromo-substituted azobenzene derivatives provides easy access to a new class of azo dyes. The properties of these compounds are compared to those of analogous compounds containing only benzene rings.