Preparation of 2,3-Dibromo-1 H -indenes and Tetrabromodihydro- s -indacenes as Synthetic Building Blocks.

The acid-induced intramolecular cyclization of 1,1-disubstituted 3-aryl-2,3-dibromoallylalcohols affords 2,3-dibromo-1 H -indene derivatives. This method is also applicable to the preparation of tetrabromodihydro- s -indacenes. The thus obtained multi-brominated compounds can serve as versatile synthetic building blocks to obtain a variety of indene and indacene derivatives, as demonstrated by the synthesis of dialkylmethylene-bridged oligo(phenylenevinylene)s, which feature attractive photophysical properties.