Skimmianic acid

When treated with aleoholie alkalis the y-methoxyl group in skimmianine is replaced by the alkyloxy group of the alcohol used. The ethoxy-analogue, C1JH15O4N, has m.p. 138°, yields a picrate, m.p. 194°, is re-converted to skimmianine by boiling with methyl alcohol, with methyl iodide yields woskimmianine, and is oxidised to the ethoxy-analogues of skimmianal, m.p. 212°, and skimmianic acid, m.p. 225° (I EtO in 4). 

XIX) to be identical with the degradation product of skimmianic acid. 

The biosynthesis of the furan moiety was investigated for skimmianine, a dictamnine-related alkaloid, using Fagara coco (Rutaceae). Thus, when C-4- or C-5-labeled 3R-mevalonic acid was used in the biosynthetic pathway, C-labeled skimmianine was observed in both cases. When the labeled skimmianine was degraded, radioactive skimmianic acid was obtained from C-4-labeled 3R-mevalonic acid, but radioinactive skimmianic acid was obtained when C-5-labeled 3R-mevalonic acid was fed. Consequently, it was concluded that the C-T and C-2 carbons (furan moiety) of skimmianine were derived from the C-5 and C-4 carbons of mevalonic acid, respectively [4].The biosynthetic precursor of dictamnine is therefore a quinoline alkaloid with a prenyl moiety, derived from dimethylallylpyrophosphate (DMAPP), at the C-3 position, such as platy-desmine [5]. It was also shown that the methyl carbon of the methoxyl moiety at the C-4 position of skimmianine was derived from methionine. 

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