Total synthesis of diptoindonesin G and its analogues as selective modulators of estrogen receptors.

We have developed a versatile synthetic strategy for the synthesis of the natural product diptoindonesin G and its analogues as selective modulators of estrogen receptors. The strategy involves a regioselective dehydrative cyclization of arylacetals, a regioselective bromination of benzofurans, a sequential cross-coupling of bromo-benzofurans with aryl boronic acids, and a BBr3-mediated tandem cyclization and demethylation. Preliminary biological studies uncovered the critical and dispensable phenolic hydroxyl groups in the natural product and also revealed unexpected selectivity for isoforms of estrogen receptor.