[khouck]

Hi y'all--thiazolidinediones are used as carboxylic acid mimetics in drug design (TZD's for example). I understand the N provides electron delocalization to the O’s which increases their H-acceptor strength. Not sure how the S contributes to this although that is not my actual question. I am trying to understand if a dioxy-triazine would also function as a carboxylic acid mimetic? Not sure if my numbering is correct, but I would call this (4,6-dioxy)1,2,5-triazine. Apologies if this is not clear but I am a biologist, not a chemist! Thanks for your thoughts.

[hypervalent_iodine]

I wouldn't have thought so, if for no other reason than the fact that triazines are much larger and aromatic. I don't completely understand what you mean by dioxytriazine though, could you post an image? Do you mean dihydroxy?

That being said, it is important to note that bioisosteres (mimetics, as you call them) are largely context dependant - by definition they require only that a molecule operate by a similar biochemical mechanism, meaning that their mimetic abilities don't always translate well across different targets. I would highly recommend looking through the relevant portions of the following review by Nicholas Meanwell: https://pubs.acs.org/doi/10.1021/jm1013693

If you're looking for potential bioisosteres to assist with H bonding, you might look into squaric acid derivatives. They have been used as carboxylic acid biososteres in the past to good effect (see: http://pubs.acs.org/doi/pdfplus/10.1021/acs.jmedchem.5b01963 and http://www.sciencedirect.com/science/article/pii/S0960894X14007719)