Constituents of Boesenbergia pandurata (syn. Kaempferia pandurata): Isolation, Crystal Structure and Synthesis of (±)-Boesenbergin A

Partly racemized pinostrobin and pinocembrin, together with 2',6'-dihydroxy-4'-methoxychalcone, cardamonin and a new chalcone (±) boesenbergin A, have been isolated from Boesenbergia pandurata Schl. (syn. Kaempferia pandurata Roxb., Zingiberaceae). Spectroscopic studies and X-ray crystallographic analysis have established the structure (±)-(E)-1-[7'-hydroxy-5'-methoxy-2'-methyl- 2'-(4''-methylpent-3''-enyl)-2'H-chromen-8'-yl]-3-phenylprop-2-enone for boesenbergin A. A simple synthesis of boesenbergin A has been achieved and its acid-catalysed cyclization has been studied.