Molecule of the Day

Just like boc protects amines, TBDMS protects alcohols.


TBDMS chloride will protect alcohols. The silicon-oxygen bond is pretty strong, and the silicon-fluorine bond is even better. This provides a protecting group that’s pretty robust – fluoride reagents are typically used for removing the silyl ether. More on that shortly…


  1. #1 psi*psi
    October 6, 2008

    It can also protect acetylenes, or at least make them more soluble and amenable to a little crystal engineering magic. Although…the awkward shape can also be sort of a hindrance there…you get a bit of disorder. 🙁

  2. #2 Uncle Al
    October 7, 2008

    The magic fluoride reagent is [tetra-n-butyl] ammonium hydrogen bifluoride, (HF2)-. Whether you are dissolving stone or cleaving Si-O, it goes where mere F- lacks cooperation. Aqueous surface tensions can be high (dissolving stone). A drop of Dawn dishwashing liquid or a Fluorad surfactant helps.

  3. #3 Vince Noir
    October 7, 2008

    Oh my god! I just did a TBDMS protection of a primary alcohol using this very reagent (like 4 minutes ago). So weird…

  4. #4 Vince Noir
    October 7, 2008

    Also, it isn’t that stable. Some 90% TFA or formic acid, or even 1% HCl in dry methanol will pop it right off. Convenient when you want to remove it with another acid-labile group, a pain in the butt for orthogonality!

  5. #5 Bob
    October 15, 2008

    Xuse me, but some of your post are too condensed for a non chemist to be of interest. Perhaps the compounds are really too arcane for use outside the lab…

  6. #6 Narasimharao
    February 22, 2011

    how to deprotect O-TBDMS????

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