[TMS] [TES] [TIPS] [TBS] [TBDPS] [Back to Carb. Synthesis]

TMS - (trimethyl silyl) ether

Standard Protection Procedure

To a solution of the glycoside and triethylamine (2 eq) stirring in THF at 0° under an inert atmosphere, is added drop wise TMS-Cl (1.5 eq).  The result was allowed to warm to room temperature and stirred until complete by TLC (usually 6 h).  The solution is then concentrated in vacuo and the residue taken on directly to next step.
Removal
The glycoside is dissolved in THF (~2M) and TBAF (1M solution in THF) is added drop wise at 0° under inert atmosphere.  The reaction is allowed to warm to room temperature and stirred until complete by TLC (usually a few hours - if not complete in this time more TBAF solution may be added).  *Note - equal volumes of glacial acetic acid (compared to TBAF solution.) may be added to prevent removal of acetates or other sensitive protecting groups.  The reaction mixture is concentrated in vacuo and the residue is purified by flash chromatography (SiO2) if necessary.
References
    JACS, 1972, 94, 2549-2550.
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TES - (triethyl silyl) ether

Standard Protection Procedure

To a solution of the glycoside and imidazole (2 eq) stirring in DMF at 0° under an inert atmosphere, is added drop wise TES-Cl (2 eq).  The result is allowed to warm to room temperature and stirred until complete by TLC (usually overnight).  An equal volume of ether is added and the reaction mixture is extracted three times with water and once with brine.  The organic layer is dried (sodium sulfate) and concentrated in vacuo.  The product can then be purified by flash chromatography (SiO2) if necessary.
Removal
The glycoside is dissolved in THF (~2M) and TBAF (1M solution in THF) was added drop wise at 0° under an inert atmosphere.  The result is allowed to warm to room temperature and stirred until complete by TLC (usually a few hours - if not complete in this time more TBAF solution may be added).  *Note - equal volume of glacial acetic acid (compared to TBAF solution.) may be added to prevent removal of acetates or other sensitive protecting groups.  The reaction mixture is concentrated in vacuo and the residue is purified by flash chromatography (SiO2) if necessary.
References
    Helv. Chim. Acta, 1981, 64, 2002-2021.
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TIPS - (triisopropyl silyl) ether

Standard Protection Procedure

To a solution of the glycoside stirring in DMF at 0° under an inert atmosphere, TIPS-Cl (1.3 eq) and imidazole (1.5 eq) were added succinctly.  The result was allowed to warm to room temperature and stirred until complete by TLC (usually overnight).  The mixture is diluted with equal volume of chloroform and extracted three times with water and once with brine.  The organic layer is dried (sodium sulfate) and concentrated in vacuo.  The resulting residue is purified by flash chromatography (SiO2) if necessary.
Removal
The glycoside is dissolved in THF (~2M) and TBAF (1M solution in THF) was added drop wise at 0° under an inert atmosphere.  The result is allowed to warm to room temperature and stirred until complete by TLC (usually a few hours - if not complete in this time more TBAF solution may be added).  *Note - equal volume of glacial acetic acid (compared to TBAF solution.) may be added to prevent removal of acetates or other sensitive protecting groups.  The reaction mixture is concentrated in vacuo and the residue is purified by flash chromatography (SiO2) if necessary.
References
    JOC, 1980, 45, 4797-4798.
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TBS - (tert-butyl dimethyl silyl) ether

Standard Procedure

To a solution of the glycoside in DMF at 0° under an inert atmosphere, TBS-Cl (1.1 eq for selective primary -OH protection, 1.3 eq otherwise) and imidazole (1.3 to 1.5 eq) were added succinctly.  The result was allowed to warm to room temperature and stirred until complete by TLC (usually overnight).  The mixture is diluted with equal volume of chloroform and extracted three times with water and once with brine.  The organic layer is dried (sodium sulfate) and concentrated in vacuo.  The resulting residue is purified by flash chromatography (SiO2) if necessary.
OR
To a solution of the glycoside and distilled 2,6-lutidine (2.1 eq) in dry DCM under an inert atmosphere at -78°, TBS-OTf is added drop wise over 30 minutes.  The result is stirred until complete by TLC (usually 30 minutes - if not complete more TBS-OTf may be added) and methanol is added.  The mixture is diluted with chloroform, washed with water and brine, dried over magnesium sulfate and concentrated in vacuo.  The resulting residue is purified by flash chromatography (SiO2) if necessary.
Removal
The glycoside is dissolved in THF (~2M) and TBAF (1M solution in THF) was added drop wise at 0° under an inert atmosphere.  The result is allowed to warm to room temperature and stirred until complete by TLC (usually a few hours - if not complete in this time more TBAF solution may be added).  *Note - equal volume of glacial acetic acid (compared to TBAF solution.) may be added to prevent removal of acetates or other sensitive protecting groups.  The reaction mixture is concentrated in vacuo and the residue is purified by flash chromatography (SiO2) if necessary.
References
    JACS, 1997, 119, 449-450.
    JACS, 1972, 94, 6190-6191.
    JOC, 1987, 52, 622-635.
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TBDPS - (tert-butyl diphenyl silyl) ether

Standard Procedure

The glycoside is dissolved in DMF at room temperature under an inert atmosphere and treated with imidazole (2 eq per -OH) followed by TBDPS-Cl (1.5 eq per -OH).  The reaction mixture is stirred until complete by TLC (usually overnight), diluted with ether and washed with 1M HCl followed by brine.  The organic layer is dried (magnesium sulfate) and concentrated in vacuoThe resulting residue is purified by flash chromatography (SiO2) if necessary.
Removal
To a solution of the glycoside in THF at room temperature in a Nalgene container, commercially available 30% HF in pyridine is added drop wise under an inert atmosphere.  The result is stirred until complete by TLC (usually 16 h) and diluted with slow addition of saturated sodium bicarbonate.  Chloroform is added and the mixture is extracted successively with water, saturated copper sulfate, and brine.  The organic layer is then dried (sodium sulfate) and concentrated.  The resulting residue is purified by flash chromatography (SiO2) if necessary.
References
   JACS, 1997, 119, 449-450.
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