The I3C chemical shifts and a large collection of coupling constants have been measured for 169 N-substituted azoles with no other substituents on the ring. Simple additive models have been used to discuss both the chemical shifts and the coupling constants. The chemical shift of the substituent depends on the nature of the azole which can, accordingly, be classified into three to six families. Some structural problems (ringchain isomerism of 1-trifluoromethylsulphonyl-1,2,3-triazole, silylotropy and stannotropy) are also discussed.

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A convenient synthesis of 5alpha,8alpha,14alpha,17alpha-5,17:8,14-dimethano-5,8,14,17-tetraaza-5,6,7,8,13,14,17,18-octahydrodibenzo[e,e']benzo[1,2-a:3,4-a']dicyclooctene derivatives is described, and the compounds have been fully characterized by NMR; in some cases, the molecular structure has been determined by X-ray crystallography. These compounds represent the first examples of a new class of molecular tweezers.

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Abstract.-Bean biochemical composition has been extensively analyzed inCoffea species because of its impact on coffee beverage quality. C. pseudozanguebariae appeared as an interesting wild species because of its low caffeine and chlorogenic acid content, compounds involved in coffee bitterness. Extending the study to its leaves revealed the presence of two unknown phenolic compounds. Isolation, then identification by MS and NMR analysis proved that these compounds are two C-glucosyl-xanthones: mangiferin and isomangiferin. HPLC analyses indicated very high mangiferin content in young leaves. This class of compounds is described for the first time not only in coffee plants but also in the Rubiaceae family. The interest of mangiferin identification in the Coffea genus is discussed.Key words : C-glucosyl-xanthones -Coffea pseudozanguebariae -leavesmangiferin -Rubiaceae.Résumé.-La composition biochimique des grains de café a été très étudiée en raison de son impact sur la qualité de la boisson. Coffea pseudozanguebariae apparaît comme une espèce sauvage intéressante en raison de sa faible teneur en caféine et en acide chlorogénique, composés participant à l'amertume du café. L'analyse étendue aux feuilles de cette espèce a révélé la présence de deux composés inconnus. Leur isolement puis leur détermination par SM et RMN prouvent qu'il s'agit de deux C-glucosyl-xanthones : la mangiférine et l'isomangiférine. Les dosages par CLHP ont montré une teneur particulièrement éle-vée en mangiférine dans les jeunes feuilles. C'est la première fois que cette classe de composés est décrite, non seulement chez un caféier mais aussi dans la famille des Rubiaceae. L'intérêt de l'identification de la mangiférine dans le genre Coffea est discuté.

Flavonoids extracted from marigold flowers were investigated for their dyeing potential. Patulitrin (1) and patuletin (2) were isolated and their structures established using NMR and HPLC-MS. These compounds were identified as the main flavonoids present in the dyeing bath. Following the dyeing process, it was demonstrated that aglycone 2 bound more strongly to wool fibres than its glucoside 1. Moreover, analysis focused on 1 and 2 dynamics during plant growth revealed that these components were only found in flowers during and after flowering. The influence of growing location was also investigated and it appeared that cultivation under Mediterranean conditions enhanced biosynthesis of 1 and 2 . Finally, several solvents were tested for their potential to extract the flavonoids: the use of a water-ethanol mixture gave a high extraction efficiency and allowed selective extraction of 1 and 2. The implications of these results are discussed in relation to the development of marigold as a potential dyeing plant.

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