Rutaretin

Diacetylhexahydromarmesin 276 has been converted into the ortho-rearranged product 277 in 30.6% yield among other photoproducts. Transformation of 277 into methyl hexahydrorutaretin methyl ether 278 served to determine the absolute configuration of rutaretin methyl ether (279) (Scheme 70) [199]. 

In more recent studies this Italian group has examined further certain aspects of linear furanocoumarin biosynthesis. The isomer of rutaretin, 5-hydroxymarmesin (19), was shown by the use of a tritiated substrate to serve as a precursor of bergapten (20) in R. graveolens, and also in Ficus carica. 5-Hydroxymarmesin, although a recognized natural product, has apparently not been reported from these two species, and for this reason its status as a natural intermediate, in contrast to rutaretin, remains uncertain. 

The PFR has also been used as a key step in the synthesis of more complex natural products or biologically active compounds, such as capiUarol [165], bikaverin [166, 167], adriamycin [168, 169], rutaretin methyl ether [170], arizonine and caseadine [171 ], diazonamide [172], and Strychnos andAspidosperma alkaloids [173]. Amore recent example is the elegant synthesis of (-)-kendomy cin involving the intramolecular PFR of a macrocyclic lactone (Scheme 31.17) [174,175]. 

Schneider, G., H. Muller, and P. Pfaender Rutaretin, ein neues Furocumarin aus Ruta graveolens L. Arch. Pharm. 300, 73 (1967). 

Ishii, H., Sekiguchi, F., and Ishikawa, T, Studies on the chemical constituents of rutaceous plants. XLI. Absolute configuration of rutaretin methyl ether. Tetrahedron, 37,285, 1981. 

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