Monatsh Chem (2009) 140:181–184
DOI 10.1007/s00706-008-0054-x
ORIGINAL PAPER
Ferric perchlorate as an efficient and useful catalyst
for the selective benzylation and methylation of alcohols
with benzyl chloride and methyl iodide
Farahnaz K. Behbahani Æ Majid M. Heravi Æ
Hossien A. Oskooie
Received: 6 August 2008 / Accepted: 15 August 2008 / Published online: 7 October 2008
Ó Springer-Verlag 2008
Abstract A mild and efficient method was developed for
selective benzylation and methylation of hydroxyl com-
pounds in the presence of a catalytic amount of ferric
perchlorate. We showed that ferric perchlorate was very
effective in selectively promoting the benzylation and
methylation of primary aliphatic and benzylic alcohols
versus secondary aliphatic alcohols and phenolic hydroxy
groups.
stable methyl ether to the more elaborate, substituted trityl
ethers developed for use in nucleotide synthesis. Ethers are
formed and removed under a wide variety of conditions.
There have been many reports on the formation of the ether
linkage, but a few are presented from hydroxyl compounds
and halides [1]. Numerous methods are available for pro-
tecting an alcohol moiety. Conversion into corresponding
ethers has been recognized as a common and useful method
for the protection of hydroxyl groups. Most commonly
used protecting groups are the tetrahydropyranyl (THP), t-
butyldimethylsilyl (TBDMS), and benzyl (Bn) groups.
Benzyl ethers are widely utilized as alcohol protecting
groups. They are easily installed, but with poor selectivity
between primary and secondary alcohol groups [2, 3], e.g.,
in carbohydrates, are stable to a wide range of reagents, and
are readily removed in the presence of many common
functionalities via catalytic hydrogenolysis, dissolving
metals, or Lewis/Brønsted acids [4]. In other words,
selectivity of reaction pathways is extremely important in
organic reactions, such as etherification [5–7].
Keywords Benzylation Á Hydroxy compounds Á
Alcohols Á Ferric perchlorate Á Etherification Á Methylation
Introduction
Hydroxyl groups are present in a number of compounds of
biological and synthetic interest, including nucleosides,
carbohydrates, steroids, macrolides, polyethers, and the
side chain of some amino acids. In some oxidation reac-
tions, such as acylation, halogenation with phosphorus,
hydrogen halides, or dehydration of these compounds, a
hydroxyl group must be protected. In polyfunctional mol-
ecules, selective protection becomes an issue that has been
addressed by the development of a number of new meth-
ods. Ethers are among the most used protective groups in
organic synthesis and vary from the simplest, the most
Recently, we have reported etherification of allylic and
benzylic alcohols with aliphatic alcohols in the presence of
ferric perchlorate [8] and the ability of ferric perchlorate as
a catalyst for some kinds of transformations in organic
synthesis [9–12]. In continuation of our works to develop
new synthetic methodologies [13–23], we wish to report an
effective, inexpensive, and selective benzylation and
methylation of hydroxyl groups using ferric perchlorate
(Scheme 1).
M. M. Heravi (&) Á H. A. Oskooie
Department of Chemistry, School of Sciences,
Azzahra University, Vanak, Tehran, Iran
e-mail: mmh1331@yahoo.com
Results and discussion
F. K. Behbahani
Department of Chemistry, School of Sciences,
Islamic Azad University, Karaj branch, Karaj, Iran
e-mail: farahnazkargar@yahoo.com
Initially, a systematic study was carried out for catalytic
evaluation of ferric perchlorate for benzylation and
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Behbahani, Farahnaz K.
