Catechol 3,5,7,3,4-pentahydroxyflavane

Sesquiterpenes and flavonoids (flavones, flavanones, flavanes) are two classes of natural substances which occur frequently in plants and which have 15 C atoms in their framework. The nine 

In the H NMR spectrum five protons can be exchanged by deuterium. Here the molecular formula permits only OH groups. The shift values (5// above 7.9) identify four phenolic OH groups and one less acidic alcoholic OH function 5 = 4.0, overlapping). 

Following the principle that the coupling partner will have the same coupling constant, one can identify in the aliphatic region a C3 chain as a further part structure, C. 

Assembly of fragments A-C, taking into account the ninth double-bond equivalent, leads to the 3,5,7,3, 4 -pentahydroxyflavane skeleton D and to the following assignment of chemical shifts  

Following the principle that the eoupling partner will have the same eoupllng eonstant, one ean identify in the aliphatie region a C3 ehaln as a further part strueture, C. 

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