Hi All,
Could some one suggest an easy and efficient way to protect phenyl boronic acid with ethylene glycol?
Kind Regards
I am trying to protect two OH with Boron, through its condensation with ethylene glycol. this picture with give you an idea.
yes i understand that but why, what are you doing next? Why do you need to protect?
Oh ok well anyways that diol does not protect the boron. The only thing it does is get rid of the acidic protons but trivalent borons like the ones you have shown above are reactive.
MIDA boronates or trifluoroborates are considered protected boronic acids.
if you really want to make that one you have shown above, Gary Molander of UPenn has good procedures for preparing boronate esters
Article Palladium-Catalyzed, Direct Boronic Acid Synthesis from Aryl...
Here you go. He shows how to make the boronate esters from the diols
actually, i want to graft that boronate with some polyols but it is forming complex due to its acidic nature. so, for that reason, i dont want these hydroxyls to interfere before. so, thats why, i am thinking about attaching it to ethylene glycol. so, could you suggest some reaction condition for that reaction, i mentioned in image?
https://pubs.acs.org/doi/suppl/10.1021/ja1089759/suppl_file/ja1089759_si_001.pdf
See attached supporting information. You just have to take up your boronic acid in CH2Cl2 and then add your diol and let stir overnight.
If I am not mistaken there is another thread with several answers to this question! perhaps you have there your answer.
https://www.researchgate.net/post/How_can_I_protect_a_boronic_acid_compound
Good luck.
I would recomend protecting with pinacol instead of ethylene glycol. The pinacol boronate ester is more stable the ethylene glycol ester. Also in the pinacol protected boronate ester, the boron remain trivalent, in contrast to MIDA boronate where it becomes tetra coordinate and later difficult to deprotect.
For protection with pinacol, just stirr the CH2Cl2 solution of boronic acid with pinacol and then run flash column. Alternatively you can buy the pinacol protected boronate ester directly.
Preparation of Boronic Acids - American Chemical Society
https://www.acs.org/content/acs/en/pressroom/cutting-edge-chemistry/preparation-of-boronic-acids.htmlDec 19, 2016 ... In the traditional method for making boronic acids, an organolithium or Grignard reagent ... Lithium–bromine exchange of tert-butoxycarbonyl-protected 7 with ... presumably via the formation of an ethylene glycol ester in situ
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