The reaction of hyperforin with hydride reducing agents

As part of a study aimed at generating analogues of hyperforin (1), the reaction of this prenylated phloroglucinol with various hydride reducing agents was investigated. Hyperforin contains two beta-dicarbonyl systems, one of which is non-enolizable, and it was interesting to assess the relative reactivity of these structural elements in the highly compact framework of the natural product. Depending on the reducing agent employed, a surprising range of compounds could be obtained, sometimes in synthetically useful yields. The stereochemistry of the LiAlH4-reduced product was secured by X-ray analysis and served as a base for elucidating the configuration of a series of reduced and deoxygenated analogues obtained with other reducing agents. The chemoselectivity observed in these reactions is apparently the result of a combination of metal-chelation and hydrogen-bonding effects. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim., Germany, 2006).