• For cleavage by PPTS, see: Synth. Commun., 1021 (1983). For cleavage by TMS chloride/ NaI or, less effectively, by preformed TMS iodide, see: Tetrahedron Lett., 25, 1429 (1984).
• For use in the protection of the OH groups in serine and threonine during peptide synthesis, see: Int. J. Pept. Prot. Res., 25, 544 (1985). See also Appendix 6.
•
Reagent for the protection of OH groups, in the presence of a base, e.g. NaH in THF or N-Ethyldiisopropylamine, A11801. The MEM-group is more readily and cleanly introduced than methoxymethyl (MOM) and is stable to a wide range of conditions. The MEM group is selectively cleaved by mild Lewis acids, e.g. ZnBr2 or TiCl4: Tetrahedron Lett., 809, 4701, 4705 (1976); 24, 3969 (1983), PPTS: Synth. Commun., 13, 1021 (1983), in situ generated TMS iodide: Tetrahedron Lett., 25, 1429 (1984), or CeCl3: Org. Lett., 3, 1149 (2001).•
MEM ethers have the ability to coordinate to metals, which is thought to accelerate the cleavage by Lewis acids. The chelating ability of the MEM ether also makes it useful as a stereodirecting group in organometallic reactions, first noted in the stereocontrolled addition of ɑ-methoxyvinyllithium to a carbonyl in the synthesis of taxusin: J. Am. Chem. Soc., 110, 6558 (1988), and subsequently in the addition of MeLi to an ɑ?-unsaturated sulfone: J. Am. Chem. Soc., 113, 3085 (1991); see 2,2,2-Trifluoroethanol, A10788, for another example.
刺激性 (Xi)
有毒 (T)
