Problems with steric hindrance evaluation

We use steric hindrance expressions in selectivity rules in a Metabolizer library that was created in-house.  Metabolizer versions 15.8.17.0 and 15.9.21.0 are both having problems evaluating the steric hindrance of atoms in some molecules.  The problem seems to occur in molecules with fused ring structures.  

For example, an "Enumeration failed" error message is encountered when Metabolizer evaluates the steric hindrance of atom # 7 or 8 in the SMILES string for chlorendic anhydride: ClC1=C(Cl)C2(Cl)C3C(C(=O)OC3=O)C1(Cl)C2(Cl)Cl

Another example is the evaluation of the steric hindrance of the nitrogen atoms in glycoluril:  O=C1N[C@@H]2NC(=O)N[C@@H]2N1 .  In this case, Metabolizer does eventually generate a solution after an excessive amount of time (~ 30 minutes).

Metabolizer version 14.11.10.0 evaluates these steric hindrance expressions quickly and without any issues.

Hi, 

Thanks for reporting this. We have managed to reproduce a strong slow-down of the steric hindrance calculation in our newest release. We will investigate it. 

Daniel

Hi, 

We managed to investigate the cause of the slow-down. It was due to a slow-down in the conformer generation process for molecules with fused rings. We will provide a bugfix for it in next week's release.

Best regards, 

Daniel