Ravenia

Ravesilone (33) i another compound of this type, has been isolated from Ravenia speatablis (P. Bhattacharyya and B.K. Chowdhury, Phytochem., 1984, 23, 1825). 

The alkaloids from Ravenia spectabilis and Flindersia ifflaiana exhibit an interesting structural variation within the quinoline group and some evidence has been presented for their genesis via biological Claisen rearrangements. ... 

Lemonia spectabilis Lindl. (Ravenia spectabilis Engl) (Rutaceae)... 

C. Alkaloids of Flindersia ifflaiana F. Muell and Ravenia spectabilis Engl. 171... 

Paul and Bose (28) examined the alkaloids of Ravenia spectabilis (Lemonia spectabilis Lindl.), and by NMR spectroscopy they identified the... 

Talapatra and co-workers (200) also studied the Ravenia alkaloids and recorded the isolation of (—)-ravenoline mp 98-99° [a]D—5 1° (CHCIj) rather than the dextrorotatory enantiomer obtained by Paul and Bose. This discrepancy has not yet been resolved. Another alkaloid isomeric with ravenoline was first called spectabiline, but to avoid confusion with another compound of the same name this was later changed to lemobiline. (-)-Lemobiline (267) (mp 198° picrate, mp 198°) is identical with the alkaloid isolated from F. ifflaiana. Lemobiline and ifflaiamine retain water of crystallization tenaciously, and this probably accounts for the widely different melting points recorded for the alkaloids. 

These unique alkaloids were obtained by Yunusov and co-workers from Haplophyllum bucharicum and appear to be derived from geranyl pyrophosphate. Although all structures have not been established, the alkaloids seem to be geranyl analogs of the Ravenia bases and are therefore considered in this section. 

The occurrence of (1,1-dimethylallyl)- and (l,2-dimethylallyl)quinoline derivatives in Flindersia and Ravenia species and the isolation of the prenyl ether 261 from Ravenia (Section V,B) suggested that the biosynthesis of this group of alkaloids might proceed via Claisen and abnormal Claisen rearrangements as in the synthetic route (Scheme 22, Section V, B). 

Lemobiline II l,2, 2, 3 -tetraMe Euxylophora paraensis [44], Flindersia ifflaiana [42], Ravenia spectabilis [42]... 

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