An Improved and Versatile Method for the Rapid Synthesis of Aryldihydrobenzofuran Systems by a Boron Tribromide-Mediated Cyclization Reaction.

Boron tribromide is presented as a highly reactive reagent that simultaneously allows the demethylation and fully diastereoselective cyclization of different precursor molecules, obtained by an aldol-type reaction, to a series of hydroxylated aryldihydrobenzofuran systems in racemic form. The latter are often found as key structures in natural compounds of different classes. Syntheses of educts, which mainly took advantage of a versatile Rieche formylation, are also described.