Highly regioselective ring opening of epoxides with polymer supported phenoxide and naphthoxide anions

Article abstract of DOI:10.1081/SCC-200026220

Amberlite IRA-400 supported phenoxide and naphthoxide anions are easily prepared. These polymer supported reagents that are highly air stable are used for the regioselective ring opening reactions of different epoxides to give aryl ether alcohols in high yields under mild reaction conditions.

Full text of DOI:10.1081/SCC-200026220

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Highly Regioselective Ring
Opening of Epoxides with
Polymer Supported Phenoxide
and Naphthoxide Anions
B. Tamami a , N. Iranpoor a & R. Rezaei a
a Chemistry Department, College of Sciences,
Shiraz University, Shiraz, 71454, Iran
Published online: 10 Jan 2011.
To cite this article: B. Tamami , N. Iranpoor & R. Rezaei (2004) Highly
Regioselective Ring Opening of Epoxides with Polymer Supported Phenoxide and
Naphthoxide Anions, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 34:15, 2789-2795, DOI: 10.1081/
SCC-200026220
To link to this article: http://dx.doi.org/10.1081/SCC-200026220
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SYNTHETIC COMMUNICATIONSw
Vol. 34, No. 15, pp. 2789–2795, 2004
Highly Regioselective Ring Opening
of Epoxides with Polymer Supported
Phenoxide and Naphthoxide Anions
*
B. Tamami, N. Iranpoor, and R. Rezaei
Chemistry Department, College of Sciences,
Shiraz University, Shiraz, Iran
ABSTRACT
Amberlite IRA-400 supported phenoxide and naphthoxide anions are
easily prepared. These polymer supported reagents that are highly air
stable are used for the regioselective ring opening reactions of different
epoxides to give aryl ether alcohols in high yields under mild reaction
conditions.
Key Words: Functionalized polymer; Polymer supported phenoxides;
Polymer supported naphthoxide; Aryl-ether alcohols; Epoxide.
*
Correspondence: B. Tamami, Chemistry Department, College of Sciences, Shiraz
University, Shiraz 71454, Iran; E-mail: tamami@chem.susc.ac.ir.
2789
DOI: 10.1081/SCC-200026220
0039-7911 (Print); 1532-2432 (Online)
www.dekker.com
Copyright # 2004 by Marcel Dekker, Inc.

2790
Tamami, Iranpoor, and Rezaei
1. INTRODUCTION
Polymeric reagents have proven useful for many chemical transform-
ations in organic synthesis.[1] Among the advantages of polymer supported
reagents are easy work-up, reuse of the supported reagent after regeneration,
and clean reaction condition.
The ring opening reaction of epoxides by nucleophiles is an interesting
approach in organic synthesis.[2] and it has been performed by a variety of
nucleophiles generally with the use of metal containing catalyst systems,
Ref.[3] or very recently reported, by the use of a polymeric phase transfer
catalyst.[4–6]
There are a few reports in the literatures on the ring opening of epoxides
with phenols and naphthols.[7] The reactions usually occur in the presence of
tertiary amines or under alkaline conditions in aqueous media at high tempera-
ture. The use of micellar media for the reaction of epoxides with phenoxide
anion catalyzed by ceric triflate catalyst has been reported very recently.[8]
As far as we know, there has been no report in the literature on the use of
polymer supported phenoxide and naphthoxide anions for the ring opening of
epoxides. Here, we report a very simple and efficient method for the regio-
selective ring opening of epoxides with Amberlite IRA-400 (ArO2,
Ar55Ph, naphthyl) in high yields under nonaqueous condition avoiding the
use of any catalyst and bases (Sch. 1).
2. RESULTS AND DISCUSSION
The Amberlite IRA-400 phenoxide or naphthoxide anion resin was easily
prepared by the reaction of Amberlite IRA-400 (Cl2 form) with aqueous
sodium salt of different substituted phenols or naphthol. Unlike the ordinary
phenoxides or naphthoxides that are air sensitive and should be prepared
just prior to their use, these polymer supported counterparts are highly air
stable and can be kept for months without any oxidation. The polymer
supported anions were used for the regioselective ring opening of different
epoxides. The effects of solvent and molar ratio of the polymer on the ring
opening reaction of epoxides were investigated. The reactions were carried
Scheme 1.

Ring Opening of Epoxides
2791
out in benzene, acetonitrile, dichloromethane, and ethanol. The experimental
results showed that ethanol was the most suitable solvent. The optimum molar
ratio of polymer supported phenoxide or naphthoxide to the epoxide was
found to be 3 : 1. The used polymeric reagents can be regenerated and used
several times without any decrease in their reactivity. In addition, the use of
polymer supported phenoxides carrying electron-withdrawing group can
also be performed without difficulty.
Except for the reaction of styrene oxide, which produced some of the
other regio-isomer (Table 1, entry 1) as a side product, the reaction of other
epoxides were found to be highly regioselective and only one isomer was
obtained (Table 1). In the case of cyclohexene oxide, trans-product was pro-
duced. Obviously, in these reactions, the attack appears to be largely at the
primary carbon atom of the epoxide ring and this is probably dictated by
steric and electronic factors. The results obtained for the ring opening of
different substituted epoxides with the polymer supported phenoxide and
naphthoxide ions are shown in Tables 1 and 2.
The advantages of using these air stable polymer supported phenoxides
or naphthoxide for the ring opening of epoxides over other methods reported
in the literature are nonaqueous and neutral reaction conditions, no catalyst
used, easy reaction work-up, and the regeneration and reuse of the polymeric
reagent.
3. EXPERIMENTAL
3.1. Material and Techniques
Products were characterized by the comparison of their physical data with
those of known samples. Gas chromatography was recorded on a Shimadzu
1
GC 14-A. IR spectra were recorded on Perkin Elmer 781 spectrometers. H
and 13C NMR spectra were recorded on Bruker DPX 250.
3.2. Preparation of Polymer Supported Aryloxides
Commercially available Amberlite IRA-400 (Cl2 form) placed in a
column was washed by an aqueous sodium salt of phenol or b-naphthol
(0.25 N) until complete removal of Cl2 ions (AgNO3 test). Then, the resin
was successively washed with water, ethanol, and ether until the excess of
aryloxide anion was removed (alcoholic FeCl3 test). The resin was finally
dried over anhydrous phosphorous pentoxide for 10 hr under vacuum at
508C. The exchange capacity was determined by passing 1 M aqueous

2792
Tamami, Iranpoor, and Rezaei

Ring Opening of Epoxides
2793

2794
Tamami, Iranpoor, and Rezaei
Table 2. Reaction of epoxides with Amberlite IRA-400 supported b-naphthoxide in
ethanol.a
Time
(hr)
Yield
(%)c
Entry
1
Epoxide
Productb
2
85
2
3
2
2
80
82
4
5
2
2
85
85
6
7
2
2
80
85
aReactions were carried out at 508C.
bProducts were identified by comparison of their IR and NMR spectra and/or physical
data with the authentic samples.[7d]
cYield refers to an isolated product.
sodium chloride (100 mL) through the resin (0.3 g) placed in a column. The
amount of aryloxide anion in the eluent was determined by titrating against
0.01 N hydrochloric acid using methyl orange as indicator. The exchange
capacity of polymer supported aryloxide anion reagent was found to be in
the range of 1.3–1.4 mmol/g of dry resin.

Ring Opening of Epoxides
2795
3.3. General Reaction
Amberlite IRA-400 phenoxide (naphthoxide) anion resin (3 mmol),
epoxide (1 mmol), and ethanol (10 mL) were stirred at 508C for 1 hr. Progress
of the reaction was followed by TLC and/or GC. After completion of the reac-
tion, the resin was filtered-off and washed with ethanol. The filtrate was dried
with sodium sulfate and the solvent evaporated to give high to excellent yield
of the product. The regeneration of the used resin can be easily achieved by
washing it first with 1 M aqueous sodium chloride and subsequently with
sodium aryloxide solution.
ACKNOWLEDGMENT
We are thankful to Shiraz University Research Council for the partial
support of this work.
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Society: Washigton, DC, 1986; 12; (b) Sherrington, D.C.; Hodge, P.
Synthesis and Separation Using Functional Polymers; John Wiley: England,
1988; (c) Akelah, A.; Sherrington, D.C. Chem. Rev. 1981, 81, 557;
(d) Akelah, A.; Moet, A. Functionalized Polymers and Their Applications;
Chapman and Hall: New York, 1990.
2. Smith, J.C. Synthesis 1984, 629.
3. (a) Chini, M.; Crott, P.; Cardelli, C.; Macchina, F. Synlett 1992, 673;
(b) Tamami, B.; Iranpoor, N.; Karimizarchi, M.A. Polymer 1993, 34,
2011; (c) Bonini, C.; Righi, G. Synthesis 1994, 225; (d) Ciaccio, A.;
Stanescu, C.; Bontemps, J. Tetrahedron Lett. 1992, 33, 1431.
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6. Tamami, B.; Mahdavi, H. React. Funct. Polym. 2002, 51, 7.
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Received in The Netherlands November 19, 2002