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Topic: About protection of hydroxyl group  (Read 3510 times)

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Offline krid1232

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About protection of hydroxyl group
« on: January 25, 2016, 11:50:02 PM »
I was wondering if anybody could advice me about protecting the -OH group in this molecule.
I want carry out a coupling reaction after protecting -OH and then deprotected it back.
« Last Edit: January 26, 2016, 12:57:43 AM by krid1232 »

Online Hunter2

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Re: About protection of hydroxyl group
« Reply #1 on: January 26, 2016, 01:00:23 AM »
Trimethylsilyl- could work .   (CH3)3Si-

Offline BRSM

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Re: About protection of hydroxyl group
« Reply #2 on: February 07, 2016, 02:40:02 PM »
I'd definitely consider trying the reaction with it unprotected. Suzuki or Stille would probably be cool with that. Otherwise something standard like benzyl or larger silyl. Depending on what coupling you use, TMS might be a bit flimsy.

Offline wildfyr

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Re: About protection of hydroxyl group
« Reply #3 on: March 05, 2016, 03:11:37 PM »
TBDMS (tertbutyldimethyl silane) is your man. Its my favorite reaction, you do it in DCM or DMF (DMF supposedly gives better conversion, but I find the workup more of a pain), then just wash with water. 1.2 eq of TBDMS-Cl 2.4 eq imidazole (http://onlinelibrary.wiley.com/doi/10.1002/anie.201506253/abstract supporting information). Literally NEVER fails and gives >80% even if you do the reaction carelessly, more if you do things carefully. If there is a lot fo "grease" from TBDMS dimer, then you can run a simple plug with hexane to elute the dimer, then push your pdt off with DCM or something polar.

TBDMS is pretty tough, it hydrolyzes VERY slowly, and can even handle weak acidic conditions sometimes. Deprotect quantitatively with a fluoride source (TBAF is popular, but aqueous KF probably does the trick too). Your hydroxylamine is a little weird to use here, but I bet it still works fine

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