How to draw structure with correct S-group brackets

[ihuang8]

I have a molecule that looks like this:

How can I build this in ketcher? I can't seem to get my SRU brackets to be aligned properly. When I try to add the SRU brackets, I get the following:

[flange-ipb]

Hi @ihuang8,

(1) you also need to have the polymer side chain inside the S-Group selection and (2) be very careful in the selection of the backbone atoms and bonds to be included in the S-Group in order to get the correct star atom arrangement.

Please see my screenshot on how to place the selection box for the S-Group (Ketcher v2.20.0):

The resulting SRU polymer is:

(I'd say the hydrogens on the star atoms are a bug.)

After a structure cleanup and a bit of rotation (hold CTRL to get finer rotation intervals) I get:

Now, one last objection could be that the methylene group in the backbone is drawn on the wrong side. I think this could be resolved by rotating the initial structure a bit in order to have the correct items inside the S-Group selection box.

To be honest: Drawing SRU polymers with star atoms has been much easier in earlier Ketcher versions.