Trimethylsilyl trifluoromethanesulfonate (TMSOTf) is an organosilicon compound with the formula . It is a colorless moisture-sensitive liquid. It is the trifluoromethanesulfonate derivative of trimethylsilyl. It is mainly used to activate ketones and aldehydes in organic synthesis.
Reactions TMSOTf is quite sensitive toward hydrolysis:
It is far more electrophilic than trimethylsilyl chloride.
Related to its tendency to hydrolyze, TMSOTf is effective for silylation of alcohols:
A common use of is for the preparation of silyl enol ethers.Efficient Stereoselective Synthesis of Proanthocyanidin Trimers with TMSOTf-Catalyzed Intermolecular Condensation. Akiko Saito, Akira Tanaka, Makoto Ubukata and Noriyuki Nakajima, Synlett, 2004, volume 6, pages 1069-1073, 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.
Trimethylsilyl trifluoromethanesulfonate has a variety of other specialized uses. It has been used to install tert-alkyl groups on phosphine (R = alkyl):
PH3 + R3C–OAc + Me3SiOTf → [(R3C)2PH2]OTf
Deprotection of Boc-protected amines can be achieved using trimethylsilyl trifluoromethanesulfonate and triethylamine or 2,6-lutidine.
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.
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