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Figure 2.
Illustration of fragment substructures and their expansions
with side chains. (A) The fragment (red, Left) is a substructure
of the larger lead-like compound (Right). (B) The number of
attachment points on the fragment scaffold (A[1] to A[7]) and on
the example side chain (A[1]) was determined by generating
smiles strings of each and identifying the number of hydrogen
atoms. Each decoration was allowed only 1 attachment point at a
time (excluding ring closing within the fragment). The possible
number of lead-like expansions (≤25 HAC) that could be formed
by combining each decoration to attachment points on the 23
fragment scaffolds was calculated analytically by using Eq. 3.
(C) Structures of the different kinds of symmetry elements seen
in the fragments. In each case, the symmetrical attachment
points (e.g., A1 and A2, C1, C2, and C3) were collapsed into a
single attachment point (e.g., A1 and A2 count as only 1
attachment point). These provided a lower limit for the possible
number of compounds that contain the fragments as substructures.
The upper limit is calculated by assuming each attachment point
is unique (no symmetry).
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