Scaffold trees, molecular scaffolds

This procedure led to a unique, hierarchical classification of scaffolds, in which each scaffold in the hierarchy is a well-defined chemical entity, which is a substructure of the original molecules. Thereby more complex scaffolds can be reduced to smaller scaffolds aeating branches and several branches merge toward the inner circles of the tree. This procedure leads to a reduction of molecular complexity from multiple annulated rings at the outer rims to single ring systems at the most inner circle of the scaffold tree (Figure 9.10). 

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