Furanoheliangolide sesquiterpene

Paquette s [27] synthetic studies on sesquiterpenes furanoheliangolides such as zexbrevin possessing in their framework a 6,9-epoxycyclodeca[b]furan involve as the key synthetic steps high-pressure-promoted Diels-Alder reaction of 4-methyl-2-[(phenylmethoxy)methyl] furan 58 with 1-cyanovinyl acetate (Scheme 14). To suppress side reactions, hydroquinone was added. Near-quantitative formation of single diastereomeric adduct 59 was achieved at 12 kbar. Its conversion to tricyclic core 61 of furanoheliangolides was achieved after elaboration of the 7-oxabicyclo[2.2.1] heptene moiety and final [3,3] sigmatropic rearrangement of 60. 

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