Trimethylsilyl trifluoromethanesulfonate
Chemical compound
From Wikipedia, the free encyclopedia
Trimethylsilyl trifluoromethanesulfonate (TMSOTf) is an organosilicon compound with the formula (CH3)3SiO3SCF3. It is a colorless moisture-sensitive liquid. It is the trifluoromethanesulfonate derivative of trimethylsilyl.[1] It is mainly used to activate ketones and aldehydes in organic synthesis.
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| Names | |
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| Preferred IUPAC name
Trimethylsilyl trifluoromethanesulfonate | |
| Other names
TMSOTf Trimethylsilyl triflate TMS triflate Trifluoromethanesulfonic acid trimethylsilyl ester | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.044.136 |
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C4H9F3O3SSi | |
| Molar mass | 222.25 g·mol−1 |
| Appearance | Colorless liquid |
| Density | 1.225 g/mL |
| Boiling point | 140 °C (284 °F; 413 K) |
| Hazards | |
| GHS labelling: | |
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| Danger | |
| H226, H314 | |
| P210, P233, P240, P241, P242, P243, P260, P264, P280, P301+P330+P331, P302+P361+P354, P303+P361+P353, P304+P340, P305+P354+P338, P316, P321, P363, P370+P378, P403+P235, P405, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Reactions
TMSOTf is quite sensitive toward hydrolysis:
- (CH3)3SiO3SCF3 + H2O → (CH3)3SiOH + HO3SCF3
It is far more electrophilic than trimethylsilyl chloride.
Related to its tendency to hydrolyze, TMSOTf is effective for silylation of alcohols:[2]
- (CH3)3SiO3SCF3 + ROH + Et3N → ROSi(CH3)3 + [Et3NH]O3SCF3
A common use of (CH3)3SiO3SCF3 is for the preparation of silyl enol ethers.[3][4] One example involves the synthesis of the silyl enol ether of camphor:
It was also used in Takahashi Taxol total synthesis and in chemical glycosylation reactions.[5]
Trimethylsilyl trifluoromethanesulfonate has a variety of other specialized uses. It has been used to install tert-alkyl groups on phosphine (R = alkyl):[6]
- PH3 + R3C–OAc + Me3SiOTf → [(R3C)2PH2]OTf
Deprotection of Boc-protected amines can be achieved using trimethylsilyl trifluoromethanesulfonate and triethylamine or 2,6-lutidine.[7][8]
TMSOTf is also a useful reagent to replace metal-halogen bonds with a covalent M-O(SO2CF3) bond, the by-product being the highly volatile TMSCl which is easily removed.