stable conformation of 2,3-dimethylsuccinic acid

I was researching for answering this [question](https://chemistry.stackexchange.com/questions/166474/kolbes-electrolysis-reaction-for-alkenes-production) on Kolbe's electrolysis of 2,3-butanedicarboxylic acid (succinic acid). Turns out, this compound is not very well researched in particular, and shows few results on search engines. I did find some results for 2,3-dimethylbutanedioic acid (2,3-dimethylsuccinic acid). [PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/11848) shows the anti-conformer as the standard structure.


[![structure of 2,3-dimethylbutanedioic acid](https://i.stack.imgur.com/amm9e.png)](https://i.stack.imgur.com/amm9e.png)


Now, the compound has two stereogenic carbons and 3 isomers:


1. R-R
2. R-S
3. S-S


Do any of these isomers under any conditions show higher stability for the syn-conformer? I ask because of the possibility of $\ce{H}$-bonding:


[![hydrogen bonding in 2,3-butanedimethyl](https://i.stack.imgur.com/JkoWH.png)](https://i.stack.imgur.com/JkoWH.png)


Would the stability due to $\ce{H}$-bonding be enough to overcome the steric repulsion?




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As told in comments, the above schematic has a 7-membered ring, which are generally less stable than 6-membered rings. This prompted me to draw another diagram which has two 7-membered rings instead:


[![hydrogen bonding in 2,3-dimethylbutanedioic acid](https://i.stack.imgur.com/grxTj.png)](https://i.stack.imgur.com/grxTj.png)


I see that the rings are somewhat strained, but that doesn't mean that, at least, one of the two hydrogen bonds does not form.


