Biogenetic theory

Reexamination of the extracts of some plants has made it possible to ascertain the presence and the structures of many minor compounds.98 Anisoxide, isolated from aniseed oil, the structure of which (39) has been established through synthesis,99 does not fit in with biogenetic theories and does not show the optical activity normally to be expected from a natural substance it is actually an artifact, formed during distillation by abnormal Claisen rearrangement from compound 40, which is present in the plant.100... 

This volume covers the synthetic and structural aspects of all types of terpenoids and steroids based on the increasing importance of biogenetic theory in this work. It covers the period September 1963 to August 1970. 55 pp 11-00... 

The Tenerife group which is responsible for about 70% of all the research published on the Latin American Celastraceae has concentrated on the isolation and structural characterization of secondary metabolites almost incidentally they have also developed various transformations and partial syntheses to test biogenetic theories in vitro and prove structural correlations by means of chemical transformations [76]. 

All these easy condensations of 2-methylbut-3-ene-2-ol or 3-methylbut-2-enol (y,y-dimethylallyl alcohol) with mono- and dihydric pheniols under very mild acidic conditions do support the biogenetic theory of C-isopentenylation with y,y-dimethylallyl pyrophosphate (ref.1). 

An impressive amount of biosynthetic work in the area of sesquiterpenoids has been carried out and the results essentially confirm the aboye biogenetic theories. Ingenious tracer experiments have been devised to extract detailed stereochemical information in many cases. However, most of this work was performed on fungal metabolites, and it is not the purpose of this article to discuss details of biosynthetic studies, which will be found elsewhere (12, 19, 77, 90, 110). One basic question, though - namely the mandatory role of c-FPP in sesquiterpene biosynthesis - calls for a brief comment. 

Reticuline is a precursor of sinomenine, via sinocutine, in Sino-menium acutum (115). It is also a precursor of berberine (LXI) in Hydrastis canadensis L. and of protopine (LXII) in Dicentra spectabilis (L.) Lem. (116). In the case of the former base the i T-methyl group of reticuline is used to form the berberine carbon (carbon atom 8) of the tetracyclic alkaloid and with the latter base it is found as the same carbon atom in the heterocyclic ring of protopine. By feeding multiple-labeled (+ )-reticuline, as indicated in LXIII, to Chelidonium majus L., it was shown that it is a precursor of chelidonine (LXIV), (— )-stylopine (LXV), and protopine (LXII), and that the labeled atoms are found in the places expected from current biogenetic theories (117). 

In the present state of biogenetic theory, it cannot be assumed that the combination of the ten carbon precursor and tryptophan must always lead to a basic compound. The recent isolation of certain aspidosperma alkaloids which owe their basicity and therefore the reason they were isolated to the indoline nitrogen may mean inter alia that the analogous yohimbine derivative (lactam carbonyl group at C-5 in Chart 2.3) is also a natural product. 

Early biogenetic theories have involved the intermediacy of 6-formylsalicylic acid (5) (Fig. 7) in patulin formation. Hydroxylation of 5 to yield a hypothetical metabolite, 5-hydroxy-6-formylsalicylic acid, and subsequent... 

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