Chemical study of guyoniana and Launaea rasedifolia followed by study of reactivity of Gamma-alkylidene Butenolides.

Abstract

Herbal systems of medicine have become increasingly popular in recent years. A recent study demonstrated that about 34% of the general population used one or the other system at least once a year. In light of growing interest in herbal drugs, chemical study of medicinal plants becomes primarily important. The standardized herbal extracts are considered to be more scientific than crude drugs. Our intention through the present study was to take part in the assessment of our botanical patrimony which remains till now less explored. The first part of this thesis deals with a chemical study of two major medicinal plants: Euphorbia guyoniana and Launaea resedifolia. For E. guyoniana, the terpenoids content study was mainly targeted through the extraction, purification and identification leading to two new jadrophanes diterpenoids named as guyonianin A and B and vomifoliol whose skeletons were identified through a series of spectral data including mass spectroscopy, 1D and 2D NMR. As far as Launaea resedifolia is concerned, the coumarin content was investigated and the results revealed the presence of four coumarins, namely Cichoriin, Esculetin, Scopoletin and isoscopoletin, extracted for the first time from this species. The second part of this work deals with the study of the reactivity of alkylidene butenolides by carrying out the 1,6 addition using some organocopper reagents. The butenolides and their analogues represent a wide range of natural occurring compounds of medical and biological importance. The study gave rise to a series of new 1,6-cuprate addition products that need to be deepened through the balancing with other reagents towards the synthesis of biological active compounds.