Furanoid terpenes

The reaction was applied to an acyclic system for the synthesis of furanoid terpenes (Scheme ll)51. The palladium-catalyzed intramolecular reaction of 47 afforded 48 which was transformed to the target molecule. The latter product was obtained as a 1 1 mixture of marmelo oxide A and B, which is the isomeric mixture found in nature. 

Synthetic Applications In several syntheses toward naturally occurring furanoid terpenes, the intramolecular oxyacetoxylation was applied as a key step [125]. For example, in the synthesis of marmelo oxides A and B,... 

Furanoid terpenes have been found only in Microciona toxystila (Order Poecilosclerida) and in two families belonging to the Order Dictioceratida (Table 4). 

FIGURE 19.22 Four stereoisomers of furanoid linalool oxides. (Modi ed from Noma, Y. et al.. Reduction of terpene aldehydes and epoxidation of terpene alcohols by S. ikutamanensis, Ya-2-1, Proceedings of 30th TEAC, 1986, pp. 204-206.)... 

The last two furanoid sesterterpene listed in Chart 9 which cooccur in S. officinalis with the C21 terpenes resisted all attempts at separation. Their formulation as halfesters (98) and (99) rested largely upon the spectroscopic properties of the mixture and ozonolysis 49). 

---