• Reagent for the protection of alcohols as triisopropylsilyl (TIPS) ethers. See Appendix 4. Methods of introduction include imidazole in DMF: Tetrahedron Lett., 2865 (1974), or imidazole/DMAP: Chem. Lett., 41 (1987). Also useful for N-protection. The steric bulk of TIPS makes it useful as a regio- and stereodirecting group, allowing selective protection of primary hydroxyl in the presence of secondary: Tetrahedron Lett., 2865 (1974). TIPS ethers are more resistant to acidic hydrolysis than TBDMS ethers, but less so than tert-butyldiphenylsilyl (TBDPS) ethers. However, they are more resistant to basic hydrolysis than either TBDMS or TBDPS derivatives: J. Org. Chem., 45, 4797 (1980); 49, 3239 (1984); Tetrahedron Lett., 24, 3455 (1983).
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Cleavage is usually accomplished by treatment with F-: J. Org. Chem., 51, 4941 (1986); see Tetra-n-butylammonium fluoride, A10588. Alternative methods include dilute HCl: Tetrahedron Lett., 2865 (1974), or 80% AcOH: J. Carbohydr., Nucleosides, Nucleotides, 3, 197 (1976).•
For a comprehensive review of the TIPS group in organic chemistry, see: Chem. Rev., 95, 1009 (1995). See also Triisopropylsilyl trifluoromethanesulfonate, B21127.
Corrosive (C)