2-Alkylarylquinolin-4 -ones

Figure 2 Schematic representation of Waterman s phylogenetic diagram of the Rutales AU Aurantioideae, RU Rutoideae, Rt Rutinae, Cu Cusparieae, Di Diosmeae, Bo Boronieae, Za Zanthoxyleae, To-1, To-2 Toddahoideae, Sp Spathelioideae, Dy Dictyolomatoideae, R Findersioideae, prR proto-Rutaceae (270). (a) Distribution of 2-alkylquinolin/ones, 2-aryl- and 2-alkylarylquinohn/ones. (b) In order to facilitate the analysis the shape representing Rutoideae (RU) was repeated to show the distribution of 2-aryl- and 2-alkylarylquinolin/ones in his tribes.

It is apparent from the summary view of the alkyl-, aryl-, and alkylarylquinolin/ones reported in the Rutaceae that they help to confirm the affinity between Rutoideae tribes and provide firm support for placing the Spathelioideae and the Dictyolomatoideae close to the more primitive Zanthoxy-leae tribe. On the other hand, the bacteria and fungi are needed for more substantial chemical studies. When more data become available, it is likely that useful systematic correlations will emerge. 

More detailed studies regarding the biosynthetic pathways of the alkyl-, aryl-, and alkylarylquinolin/ones in the Rutaceae and in bacteria are needed. Such studies would clarify the differences in the pathways based on their derivation from anthranilic acid in bacteria and in rutaceous plants. 

Table 24.26 Occurrence of 2-alkylarylquinolin-4(l//)-one alkaloids in the Rutaceae species...

No data is available on the biosynthesis of alkaloids of rutaverine type found in R. graveolens (Table 24.26), in which quinolin-4(lf/)-one and phenyl ring systems are separated by a multiple carbon chain (2-alkylarylquinolin-4(l//)-ones). A similar pathway to that leading to graveoline (66), but involving condensation of p-keto intermediate with more than one acetate unit to give a polyketide chain attached to the carboxylic acyl group of the amino acid can be proposed. 

It condenses with anthranilate to form the 2-aLkylarylquinolin-4(l//)-ones. Direct supports for biogenetic ideas through the appropriate labeling studies are little from Rutaceae, but the structures of many aryl- and alkylaryquinolin/ones isolated from the mtaceous genus (Tables 24.19, 24.20, 24.26), have provided much indirect evidence for the route proposed at Schemes 24.19 and 24.20. 

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