Unexpected tautomeric states

User eab89acc2a

10-06-2010 17:11:45

This is my first post, and I would like to start by thanking ChemAxon for providing such a pleasant place to ask questions and report issues.

We have been using your tautomer generation on a large collection of drug-like molecules, and have been very satisfied with the results. There are, however, a few rare and notable exceptions. I will list two examples in this post. They have both been generated with the following options, with version 5.1.3_2:

cxcalc input.smi tautomers -D -a

First example:

input: CC(=O)CNS(=O)(=O)C1=CC=CC=C1

output: CC(O)=C=N[SH](O)(=O)C1=CC=CC=C1

The appearance of an alkadiene group was a little surprising and does not appear to be stable.

Second example:

input: CC(NC(C)=O)C(=O)c1nccs1

output: CC(O)N=C(C)C(=O)C1=NC=CS1

In this case, an amide group has been converted to an aminomethanol, which seems unusual, and also introduces a fairly significant structure change in the compound. In addition, if the output above is given to cxcalc as input, none of the other associated tautomeric states are produced, which indicates some type of inconsistency.

User 851ac690a0

10-06-2010 18:36:43



Yes, you are right.  Both output structures are incorrect.  These bugs were fixed.

Please update and download the latest version of the Chemaxon's calculators.


User eab89acc2a

10-06-2010 19:45:28

I have just discovered that we are using a rather old version of your tools, which wasn't my intent.

We've upgraded, and I can confirm that the latest version (5.3.3) produces more reasonable results. If we discover additional "unexpected" results, I will let you know.

User 851ac690a0

14-06-2010 07:28:24



If we discover additional "unexpected" results, I
will let you know.