Dummy atoms next to aromatic are always kekulized even when they should not

[ptosco]

Discussed in #4716

^{Originally posted by laurenreid1 November 19, 2021}
Hi everyone,

I'd like to depict a benzocyclohexane-like compound containing 2 dummy atoms within the cyclohexane ring (e.g c12ccccc1*-*CC2). Using the following code:

from rdkit import Chem
from rdkit.Chem import Draw
from rdkit.Chem.Draw import rdMolDraw2D

mol = Chem.MolFromSmiles("c12ccccc1*-*CC2")
dm = Draw.PrepareMolForDrawing(mol)
d2d = rdMolDraw2D.MolDraw2DCairo(240, 135)
d2d.DrawMolecule(dm)
d2d.FinishDrawing()
draw_text = d2d.GetDrawingText()

with open("test.png", "wb") as f:
    f.write(draw_text)

I receive this depicition that adds a double bond between the 2 dummies:

I believe this is happening during kekulization, where the conjugation of the dummy atoms to the benzene ring is interpreted as aromaticity? I can turn off the behaviour using the following:

from rdkit import Chem
from rdkit.Chem import Draw
from rdkit.Chem.Draw import rdMolDraw2D

mol = Chem.MolFromSmiles("c12ccccc1*-*CC2", sanitize=False)
mol.UpdatePropertyCache()
dm = Draw.PrepareMolForDrawing(mol, kekulize=False)
d2d = rdMolDraw2D.MolDraw2DCairo(240, 135)
d2d.drawOptions().prepareMolsBeforeDrawing = False
d2d.DrawMolecule(dm)
d2d.FinishDrawing()
draw_text = d2d.GetDrawingText()

with open("test.png", "wb") as f:
    f.write(draw_text)

But this leaves me with the following depiction:

Does anyone know if there's a way I can depict the benzene ring in its kekulized form while keeping the bond between the dummy atoms as a single aliphatic bond? I've been playing around with the santizeflags but haven't found a combination that will allow only the benzene bonds to be kekulized.

Thanks,
Lauren

EDIT: My RDKit version is 2020.03.3