The handling of keto-enol tautomerization by default has been
improved. The improvement extends to include imine-enamine
tautomerization and related analogs. The keto and imine forms are
favored except in the case of 1,3 diketones, where the internal
hydrogen bond can be formed.
The process for generating reasonable tautomers for many simple and complex
pyridone analogs, pyrrole analogs, and pyridine analogs have been improved.
An issue that caused double bonds and hydrogens to move too far
through a series of sp3 centers has been fixed.
The default behavior of peptide tautomers and peptide stereochemistry
have been improved.