Hibiscone synthesis

Disubstituted- and 2,3,4-trisubstituted-furans are provided by oxidation or oxidation/acid-induced cyclization of the corresponding 2-butene-l,4-diols. These methods have been successfully employed for the synthesis of hibiscone C <00SL363> and cristatic acid . 

Other sesquiterpenes whose synthesis are worthy of mention are hibiscone C (38) (also known as gmelofuran), which is found in the heartwood of Hibiscus elatuSy and herbertene (40), isolated from the liverwort Herberta adunca. The synthesis of hibiscone by Koft and Smith" can be commended for its novel use of intramolecular [2 4- 2] photocycloaddition of the acetylenic enone (36) to set up the intermediate (37), whereas Prater s synthesis of herbertene is interesting, to say the least, since it involves a one-step acid-catalysed rearrangement of the alcohol (39) ... 

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