Protecting Groups - Common Protecting Groups - Alcohol Protecting Groups

Alcohol Protecting Groups

Protection of alcohols:

  • Acetyl (Ac) - Removed by acid or base (see Acetoxy group).
  • Benzoyl (Bz) - Removed by acid or base, more stable than Ac group.
  • Benzyl (Bn, Bnl) - Removed by hydrogenolysis. Bn group is widely used in sugar and nucleoside chemistry.
  • β-Methoxyethoxymethyl ether (MEM) - Removed by acid.
  • Dimethoxytrityl, (DMT) - Removed by weak acid. DMT group is widely used for protection of 5'-hydroxy group in nucleosides, particularly in oligonucleotide synthesis.
  • Methoxymethyl ether (MOM) - Removed by acid.
  • Methoxytrityl [(4-methoxyphenyl)diphenylmethyl, MMT) - Removed by acid and hydrogenolysis.
  • p-Methoxybenzyl ether (PMB) - Removed by acid, hydrogenolysis, or oxidation.
  • Methylthiomethyl ether - Removed by acid.
  • Pivaloyl (Piv) - Removed by acid, base or reductant agents. It is substantially more stable than other acyl protecting groups.
  • Tetrahydropyranyl (THP) - Removed by acid.
  • Trityl (triphenylmethyl, Tr) - Removed by acid and hydrogenolysis.
  • Silyl ether (most popular ones include trimethylsilyl (TMS), tert-butyldimethylsilyl (TBDMS), tri-iso-propylsilyloxymethyl (TOM), and triisopropylsilyl (TIPS) ethers) - Removed by acid or fluoride ion. (such as NaF, TBAF (Tetra-n-butylammonium fluoride, HF-Py, or HF-NEt3)). TBDMS and TOM groups are used for protection of 2'-hydroxy function in nucleosides, particularly in oligonucleotide synthesis.
  • Methyl Ethers - Cleavage is by TMSI in DCM or MeCN or Chloroform. An alternative method to cleave methyl ethers is BBr3 in DCM
  • Ethoxyethyl ethers (EE) - Cleavage more trivial than simple ethers e.g. 1N Hydrochloric acid

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