Total synthesis of demethylwedelolactone and wedelolactone by Cu-mediated/Pd(0)-catalysis and oxidative-cyclization

Hedysarimcoumestan B, which can be isolated from Chinese herbal medicine, is achieved, in which the longest linear sequence is only eight steps, in 50% overall yield from commercially available phloroglucinol. The key transformations in the synthesis are Cu-mediated/Pd(0)-catalysis and I2/pyridine oxidative-cyclization reactions. This synthetic strategy can be applied to give access to the demethylwedelolactone (4) and wedelolactone (5), which were afforded from commercially available phloroglucinol in high 38 and 33% yields, respectively.