this group of compounds. The nomenclature used by various investigators in discussing the structures of phenylpropanoids
Phenylpropanoids can conveniently be treated as a large class of natural compounds consisting of the following
1. Simple phenylpropanoids:
a) cinnamyl alcohols and their derivatives (ethers, glycosides);
b) cinnamic acids and their derivatives (esters, glycosides, other derivatives);
2. Complex phenylpropanoids:
a) phenylpropanoid glycosides based on phenylethanes;
b) oxidative coupling products (lignoids): flavolignans; xanthonolignans; coumarinolignans; alkaloidolignans;
neolignans; lignans (dimers and oligomers of phenylpropanoids).
3. Biogenetically related phenylpropanoids (flavonoids, coumarins, etc.).
The classification of phenylpropanoids proposed by us is based on current impressions of the biosynthesis of phenolic
compounds, in which cinnamyl alcohols 1-4 and cinnamic acids 5-10 play key roles. The literature on the distribution in plants
of the most important phenylpropanoids (groups 1 and 2) is presented according to this classification. Flavonoids and
coumarins, the biogenetic precursors of which are phenylpropanoids, can be usefully reviewed according to an overall
classification only from the viewpoint of biosynthesis.
These compounds have been described in detail as independent classes
of natural compounds in monographs and reviews .
Compounds 1, 5, 8, 33, and 42 provide an example of the usefulness of using a conventional numbering for the
phenylpropanoid carbon atoms that enables the propane fragment in the molecule (C-7, C-8, and C-9) to be clearly identified.
For example, these correspond to the frequently used notation (C-a, C-?, and C-?). This reveals structural features of the various
groups in phenylpropanoids. In our opinion, this approach is especially critical for interpreting and comparing spectral data
during structural analyses using 1
H and 13C NMR spectroscopy and other methods.
2. DISTRIBUTION OF PHENYLPROPANOIDS IN PLANTS
The literature on the distribution in plants of the most important phenylpropanoids indicates that plants of the families
composites or asters (Asteraceae), orpines (Crassulaceae), aralias (Araliaceae), figworts (Scrophulariaceae), willows
(Salicaceae), plantains (Plantaginaceae), mezereums (Thymelaeaceae), mints (Lamiaceae), and olives (Oleaceae) are rich sources
This section examines in detail phenylpropanoids of original structure that are of greatest interest for structural stud