Benzyl ethers
Bn-OR
T. W. Green, P. G. M. Wuts, Protective Groups in Organic
Synthesis,
Wiley-Interscience, New York, 1999, 76-86, 708-711.
Stability
| H2O: | pH < 1, 100°C | pH = 1, RT | pH = 4, RT | pH = 9, RT | pH = 12, RT | pH > 12, 100°C |
| Bases: | LDA | NEt3, Py | t-BuOK | Others: | DCC | SOCl2 |
| Nucleophiles: | RLi | RMgX | RCuLi | Enolates | NH3, RNH2 | NaOCH3 |
| Electrophiles: | RCOCl | RCHO | CH3I | Others: | :CCl2 | Bu3SnH |
| Reduction: | H2 / Ni | H2 / Rh | Zn / HCl | Na / NH3 | LiAlH4 | NaBH4 |
| Oxidation: | KMnO4 | OsO4 | CrO3 / Py | RCOOOH | I2, Br2, Cl2 | MnO2 / CH2Cl2 |
Facile reductive etherification of carbonyl compounds can be conveniently
performed by reaction with triethylsilane and alkoxytrimethylsilane catalyzed by
iron(III) chloride. The corresponding alkyl ethers, including benzyl and allyl
ethers, of the reduced alcohols were obtained in good to excellent yields under
mild reaction conditions.
K. Iwanami, H. Seo, Y. Tobita, T. Oriyama, Synthesis, 2005,
183-186.
The ionic liquid [bmim][Br] confers high nucleophilicity on the bromide ion
for the nucleophilic displacement of an alkyl group to regenerate a phenol from
the corresponding aryl alkyl ether in good yield in the presence of p-toluenesulfonic
acid. Dealkylation of
various aryl alkyl ethers could also be achieved using stoichiometric amounts of
concentrated hydrobromic acid in [bmim][BF4].
S. K. Boovanahalli, D. W. Kim, D. Y. Chi, J. Org. Chem., 2004,
69, 3340-3344.
Various silyl ethers were readily and efficiently transformed into the
corresponding alkyl ethers in high yields by the use of aldehydes combined with
triethylsilane in the presence of a catalytic amount of iron(III) chloride.
K. Iwanami, K. Yano, T. Oriyama, Synthesis, 2005, 2669-2672.
Two methods are described for the regioselective displacement of the primary
hydroxy group in methyl glycosides with iodide. Products of the first method
employing triphenylphosphine and iodine need purification on a reverse phase
column. A one-pot procedure via sulfonates and subsequent substitution with
iodide and methods for the protection of the iodoglycosides are also described.
P. R. Skaanderup, C. S. Poulsen, L. Hyldtoft, M. R. Jørgensen, R. Madsen, Synthesis,
2002, 1721-1727.
Aromatic aldehydes were easily converted to the corresponding ethers in
methanol or ethanol using decaborane at r.t. under nitrogen in high yields.
S. H. Lee, Y. J. Park, C. M. Yoon, Tetrahedron Lett., 1999, 40,
6049-6050.
Arylhydroxymethylphosphinic acid derivatives were prepared by a palladium(0)
catalysed arylation of ethyl benzyloxymethylphosphinate with aryl halides
followed by subsequent hydrogenolysis of the benzyl protecting group and
hydrolysis of the ester function.
H.-J. Cristau, A. Hervé, F. Loiseau, D. Virieux, Synthesis,
2003, 2216-2220.
