Synthesis and characterization of a highly fluorescent benzofuran dimer derived from estradiol

Abstract

Pd-catalyzed cyclization of a fluorescent dimer in which two cores of the potent estrogenic estradiol are bridged by the 1,4-diethynil benzene moiety led to a steroid dimer bearing the 1,4-di(benzofuran-2-yl)benzene. The obtained compound showed an intense blue fluorescence characterized by a broad emission band between 350 and 550 nm, with four maxima at 384, 403, 435, and 456 nm. The benzofuran dimer showed an 18-fold increased quantum yield compared with that of its synthetic precursor.