Zirconium (IV) Chloride Catalyzed Ring Opening of Epoxides with Aromatic Amines

Article abstract of DOI:10.1081/SCC-120027721

Zirconium (IV) chloride catalyzed ring opening of epoxides with anilines to afford the corresponding β-amino alcohols in acetonitrile at ambient temperature was discussed.

Full text of DOI:10.1081/SCC-120027721

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Zirconium (IV) Chloride Catalyzed Ring Opening of
Epoxides with Aromatic Amines
N. Raghavendra Swamy a , T. Venkateshwar Goud a , S. Malla Reddy a , P. Krishnaiah a &
Y. Venkateswarlu a
a Organic Chemistry Division‐I, Natural Products Laboratory , Indian Institute of Chemical
Technology , Hyderabad, 500 007, India
Published online: 16 Aug 2006.
To cite this article: N. Raghavendra Swamy , T. Venkateshwar Goud , S. Malla Reddy , P. Krishnaiah & Y. Venkateswarlu
(2004) Zirconium (IV) Chloride Catalyzed Ring Opening of Epoxides with Aromatic Amines, Synthetic Communications:
An International Journal for Rapid Communication of Synthetic Organic Chemistry, 34:4, 727-734, DOI: 10.1081/
SCC-120027721
To link to this article: http://dx.doi.org/10.1081/SCC-120027721
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SYNTHETIC COMMUNICATIONSw
Vol. 34, No. 4, pp. 727–734, 2004
Zirconium (IV) Chloride Catalyzed
Ring Opening of Epoxides with
Aromatic Amines
N. Raghavendra Swamy, T. Venkateshwar Goud,
S. Malla Reddy, P. Krishnaiah, and Y. Venkateswarlu
*
Organic Chemistry Division-I, Natural Products Laboratory, Indian
Institute of Chemical Technology, Hyderabad, India
ABSTRACT
Zirconium (IV) chloride catalyzed ring opening of epoxides with anilines
to afford the corresponding b-amino alcohols in acetonitrile at ambient
temperature was discussed.
Key Words: Epoxide; Aromatic amine; Zirconium (IV) chloride.
Introduction of amino functionality in to organic molecules has highest
prominence in synthetic organic chemistry. b-amino alcohols are useful
*
Correspondence: Y. Venkateswarlu, Organic Chemistry Division-I, Natural Products
Laboratory, Indian Institute of Chemical Technology, Hyderabad 500 007, India;
Fax: þ91-40-27160512; E-mail: luchem@iict.res.in.
727
DOI: 10.1081/SCC-120027721
0039-7911 (Print); 1532-2432 (Online)
www.dekker.com
Copyright # 2004 by Marcel Dekker, Inc.

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Swamy et al.
intermediates for the synthesis of many biologically active natural and
synthetic products.[1–4] Classically these compounds were synthesized by the
opening of an epoxide with excess amine at elevated temperature.[5] A variety
of activators have been introduced in the literature such as metal triflates,[3]
metal halides[6] and Lewis acids or Brønsted acids to carryout the epoxide
opening with amines.[7] However there are still some limitations with
literature methods such as the high temperature long reaction time,[8] low
yields, failure of deactivated amines and sterically hindered aromatic amine.
To overcome these limitations we wish to report an efficient method for the
ring opening of epoxide with aromatic amine catalyzed by Zirconium (IV)
chloride in acetonitrile at room temperature.
Previously ZrCl4 has been used as an efficient catalyst in acetalization,
dithioacetalization[9a] and 1, 3-oxathiolanes of carbonyl compounds. Also it
has been used in transthioacetalizations of acetal,[10] and in synthesis of
chloromethyl ester.[11] We have initiated some investigations on Zirconium
(IV) chloride mediated opening of epoxide with amine for the transformation
of the b-amino alcohols in view of the current thrust on catatlyic processes.
There is merit in developing a truly catalytic opening of epoxide with amine
using inexpensive and non-polluting reagent. Herein, we wish to report
Zirconium (IV) chloride promoted ring opening of epoxides with aniline. The
reaction proceeds efficiently at ambient temperature with excellent yields.
Furthermore other functionalities such as chloro, OH, CH3 and OCH3 were
compatible under the reaction conditions. The reaction conditions are very
mild and no by products were observed. We first examined the reaction of
styrene oxide with aniline in the presence of Zirconium (IV) chloride in
acetonitrile at ambient temperature, which afforded the corresponding amino
alcohol in 96% yield (entry 2). This success has encouraged us to extend the
generality of the reaction to other epoxides with various amines. All the
products are fully characterized by 1H NMR, IR and mass spectral data. The
trans stereochemistry of amino alcohol (Table 1) was determined from the
coupling constants of ring methine protons at ꢀd 3.34 (1H, ddd, J ¼ 9.9, 9.9
Scheme 1.

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Zirconium (IV) Chloride Catalyzed Ring Opening
729
Table 1. Zirconium (IV) chloride catalyzed epoxide opening
with aromatic amines.
Entry
Amino alcohola
Yieldb
Time
a.
b.
c.
R55H, R55C6H5
R55H, Ar55C6H4-o-Me
R55C2H5, Ar55C6H5
97
96
96
1.5
1.5
1.5
d.
Ar55Ph
96
2
e.
f.
R55H, Ar55C6H5
95
95
96
97
96
95
95
2
R55H, Ar55C6H4-o-OH
R55H, Ar55C6H4-p-Cl
R55H, Ar55C6H4-o-Me
R55C2H5, Ar55C6H5
R55H, Ar55C6H4-p-OMe
R55ph, Ar55-CH2-C6H5
2
g.
h.
i.
2
2
1.5
2
j.
k.
2
l.
R55H, Ar55C6H5
95
2
aAll products were characterized by 1H NMR, IR and mass
spectral data. Comparison with the reported data.
bIsolated and unoptimized yields.
and 4.5 Hz) of CH22OH and at 3.14. (1H, ddd, J ¼ 10.8, 9.3 and 3.9 Hz) for
CH-NHPh, respectively.
In conclusion it appears from this study that the Zirconium (IV) chloride
mediated epoxide opening with amine is an attractive C22N bond forming
process. The experimental simplicity, mild reaction condition, reduced

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730
Swamy et al.
reaction time, inexpensive catalyst and high yields of products, makes it as an
useful and important addition to the present existing methodologies.
EXPERIMENTAL
General Procedure for the Generation of b-amino Alcohols
from Epoxides
To a solution of an epoxide (1 mmol) and aromatic amine (1.1 mmol) in
acetonitrile (10 mL) was added Zirconium (IV) chloride (5 mol%) and stirred
for an appropriate time (Table 1) at room temperature. After completion of the
reaction, the solvent was removed from the reaction mixture under reduced
pressure, water was added and the mixture was extracted into EtOAc. The
organic layer was dried over anhydrous Na2SO4 and concentrated to give the
crude product, which was purified on silica gel column to give pure trans
amino alcohol in high yields.
trans-2-(Phenylamino) cyclopentanol (a). 1H NMR (CDCl3,
200 MHz): d 1.3–1.5 (m, 1H), 1.6–1.9 (m, 3H), 1.9–2.05 (m, 1H), 2.15–
2.35 (m, 1H), 2.4–3.1 (br s, 2H), 3.55–3.60 (dd, 1H, J ¼ 8.0, 4.5 Hz), 4.0 (dd,
1H, J ¼ 8.0, 4.5 Hz), 6.65–6.8 (m, 3H), 7.1–7.25 (m, 2H); Mass (m/z) 177
(Mþ þ 1) Anal. Calcd. for C11H15NO: C, 74.54; H, 8.53; N, 7.90 Found C,
74.69; H, 8.58; N, 7.96. m.p. 57–588C (lit. 57–588C), Yield 97%.
trans-2-(o-Methylphenylamino) cyclopentanol (b). Viscous liquid; 1H
NMR (CDCl3, 200 MHz) : d 1.35–1.5 (m, 1H), 1.55–1.85 (m, 3H), 2.2–2.45
(m, 2H), 2.8 (s, 3H), 3.9–3.95 (dd, 1H, J ¼ 8.0, 4.5 Hz), 4.2–4.3 (dd, 1H,
J ¼ 8.0, 4.5 Hz), 6.64 (dt, 1H, J ¼ 7.2, 0.6 Hz), 6.8 (d, 1H, J ¼ 8.7 Hz), 7.23
(m, 2H); Mass (m/z) 192 (Mþ þ 1); Anal. Calcd. for C12H17NO: C, 78.35; H,
8.96; N, 7.32 Found C, 78.59; H, 8.99; N, 7.34.
trans-2-(N-Ethyl-N-phenylamino) cyclopentanol (c). Viscous liquid;
1
IR (neat) 3100–3580 cm21; H NMR (CDCl3, 200 MHz): d 1.19 (t, 3H,
J ¼ 6.9 Hz), 1.6–1.71 (m, 2H), 1.8–1.93 (m, 2H), 2.0–2.12 (m, 2H), 3.28–
3.41 (m, 2H), 3.91–4.12 (dd, 1H, J ¼ 8.0, 5.0 Hz), 4.2–4.31 (dd, 1H, J ¼ 8.0,
5.0 Hz), 6.74–6.86 (m, 1H), 6.88 (tt, 1H, J ¼ 7.2, 0.9 Hz), 7.23–7.36 (m, 2H);
13C NMR (CDCl3, 100 MHz): d 14.63, 19.72, 25.69, 31.53, 40.55, 67.60,
74.93, 114.76, 129.13, 149.37; Mass (m/z) 206 (Mþ þ 1). Anal. Calcd. For
C13N19NO: C, 76.10; H, 9.27; N, 6.83. Found C, 76.32; H, 9.22; N, 6.90.
1
2-Anilino-2-phenyl-1-ethanol (d). Viscous liquid; H NMR, (CDCl3,
200 MHz) d 3.62–3.75 (dd, 1H, J ¼ 10, 7 Hz), 3.8–3.95 (dd, 1H, J ¼ 10,
5 Hz), 4.4–4.52 (dd, 1H, J ¼ 7, 5 Hz), 6.48–6.58 (d, 2H, J ¼ 5.7 Hz), 6.61–
6.68 (t, 1H, J ¼ 4.8, 11.2 Hz), 7.0–7.14 (t, 2H, J ¼ 4.8, 11.2 Hz), 7.2–7.4 (m,

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Zirconium (IV) Chloride Catalyzed Ring Opening
731
5H); Mass (m/z): 213 (Mþ þ 1) Anal. Calcd. for C14H15NO; C: 78.84; H:
7.09; N, 6.57 Found C, 78.92;H, 7.13; N, 6.62.
trans-2-(Phenylamino) cyclohexanol (e). m.p. 58–598C (lit. m.p. 60–
628C); 1H NMR (CDCl3, 200 MHz): d 1.04–1.22 (m, 1H), 1.34–1.52 (m, 3H),
1.75–1.82 (m, 2H), 2.12–2.31 (m, 2H), 3.04 (br s, 2H, NH and OH), 3.14
(ddd, 1H, J ¼ 10.8, 9.3, 3.9 Hz), 3.34 (ddd, 1H, J ¼ 9.9, 9.9 and 4.5 Hz),
6.75–6.81 (m, 3H), 7.1–7.25 (m, 2H); 13C NMR (CDCl3, 50 MHz): d 24.2,
24.9, 31.5, 33.1, 60.0, 74.3, 114.2, 118.2, 129.2, 147.7.
2-[N-(2-Hydroxycyclohexyl) amino] phenol (f). 1H NMR (CDCl3,
200 MHz): d 1.0–1.2 (m, 1H), 1.22–1.48 (m, 3H), 1.6–1.8 (m, 2H), 1.95–2.2
(m, 2H), 3.0–3.12 (ddd, 1H, J ¼ 10.8, 9.3, 3.9 Hz), 3.4–3.55 (ddd, 1H,
J ¼ 9.9, 9.9, 4.5 Hz), 4.17 (br s, 2H, exchangeable), 6.45 (t, 1H, J ¼ 7.3,
2.6 Hz), 6.7–6.81 (m, 3H), 8.8 (br s, 1H, exchangeable); Mass (m/z) 207 (65,
Mþ), 148 (100). Anal. Calcd. for C12H17NO2: C, 69.6; H, 8.2; N, 6.8. Found:
C, 69.8; H, 8.4; N, 6.6.
2-(4-Chlorophenyl) amino-1-cyclohexanol (g). 1H NMR (CDCl3,
200 MHz): d 1.0–1.18 (m, 1H), 1.25–1.36 (m, 3H), 1.7–1.82 (m, 2H),
2.05–2.15 (m, 2H), 2.7–3.1 (ddd, 1H, J ¼ 10.8, 9.3, 3.9 Hz), 3.25–3.41 (ddd,
1H, J ¼ 9.9, 9.9, 4.5 Hz), 6.55 (d, 2H, J ¼ 5.2 Hz), 7.05 (d, 2H, J ¼ 5.2 Hz);
Mass (m/z): 227 (Mþ, 48.24 37Cl), 226 ((M þ 1)þ, 61.65), 225 (Mþ 100.
35Cl), 208 (7.26), 194 (1.74), 182 (9.26), 166 (61.77), 153 (13.77), 140
(26.49), 130 (23.37), 117 (8.24), 91 (8.31); IR (KBr) nmax: 3416, 3388, 3322,
2934, 2861, 1871, 1597, 1509, 1451, 1324, 1260 cm21. Anal. Calcd. for
C12H16ClNO: C, 63.85; H, 7.14; N, 6.21. Found C, 63.56; H, 7.11; N, 6.0; m.p.
102–1048C, yield 95%.
1
trans-2-(O-Methylphenylamino) cyclohexanol (h). Viscous liquid; H
NMR (CDCl3, 200 MHz): d 1.08–1.26 (m, 1H), 1.38–1.51 (m, 3H), 1.78–
1.85 (m, 2H), 2.16 (m, 2H), 2.18 (s, 3H), 3.0 (br s, 2H, NH and OH), 3.23
(ddd,1H, J ¼ 10.9, 9.3 and 3.9 Hz), 3.44 (ddd, 1H, J ¼ 10.5, 10.5 and 4.8 Hz),
6.72–6.85 (m, 1H), 6.81 (d, 1H, J ¼ 7.8 Hz), 7.12–7.3 (m, 2H); 13C NMR
(CDCl3, 100 MHz): d 17.62, 24.21, 24.92, 31.75, 33.17, 59.72, 74.44, 111.46,
117.73, 123.0, 127.06, 130.32, 145.62; Mass (m/z) 206 (Mþ þ 1).
trans-2-(N-Ethyl-N-phenylamino) cyclohexanol (i). Viscous liquid; 1H
NMR (CDCl3, 200 MHz): d 0.9–1.15 (m, 1H), 1.2–1.29 (t, 3H, J ¼ 4.6 Hz),
1.25–1.5 (m, 3H), 1.7–1.8 (m, 2H), 2.15–2.25 (m, 2H), 2.9 (s, 1H), 3.2–3.4
(m, 3H), 3.55–3.7 (ddd, 1H, J ¼ 9.9, 9.9, 4.5 Hz), 6.8 (t, 1H, J ¼ 4.5 Hz), 6.95
(d, 2H, J ¼ 9.0 Hz), 7.25 (t, 2H, J ¼ 4.5 Hz); Mass (m/z) 219 (Mþ þ 1); Anal.
Calcd. for C14H21NO: C, 76.67; H, 9.65; N, 6.39. Found C, 76.72; N, 9.72; N,
6.42.
trans-2-(p-Methoxyphenylamino) cyclohexanol (j). m.p. 58–598C; 1H
NMR (CDCl3, 200 MHz): d 1.0–1.13 (m, 1H), 1.3–1.41 (m, 3H), 1.71–1.83
(m, 2H), 2.05–2.17 (m, 2H), 2.97 (ddd, 1H, J ¼ 10.9, 9.3, 3.9 Hz), 3.28 (s, 2H,

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Swamy et al.
NH and OH), 3.31 (ddd, 1H, J ¼ 9.6, 9.6, 3.9 Hz), 3.73 (s, 3H), 6.68 (d, 2H,
J ¼ 8.0 Hz), 6.78 (d, 2H, J ¼ 8.0 Hz); 13C NMR (CDCl3, 100 MHz): d 24.15,
24.86, 31.25, 33.07, 55.56, 61.48, 74.03, 114.67, 116.28, 141.29, 152.73; Mass
(m/z) 222 (Mþ þ 1).
trans-2-(N-Benzyl-N-phenylamino) cyclohexanol (k). Viscous liquid;
IR (Neat) nmax 3000–3600 cm21; 1H NMR (CDCl3, 200 MHz): d 1.38–1.49
(m, 4H), 1.8–1.93 (m, 2H), 1.94 (m, 1H), 2.19–2.37 (m, 1H), 2.84 (br s, 1H,
OH), 3.65–3.81 (m, 2H), 4.48 (d, 2H, J ¼ 10.5 Hz), 6.82–6.93 (m, 1H), 7.0–
7.19 (m, 2H), 7.25–7.34 (m, 3H), 7.36–7.51 (m, 4H); 13C NMR (CDCl3,
100 MHz): d 24.19, 25.38, 26.99, 33.60, 48.91, 66.38, 70.62, 116.21, 118.62,
126.62, 126.76, 128.60, 128.96, 139.58, 149.7. Anal. Calcd. for C19H23NO: C,
81.14; H, 8.19; N, 4.98. Found C, 81.42; H, 8.32, N, 5.08.
trans-2-(Phenylamino) cyclooctanol (l). Viscous liquid; IR nmax (neat)
1
3120–3620 cm21; H NMR (CDCl3, 200 MHz): d 1.6–1.73 (m, 8H), 1.86–
1.97 (m, 4H), 3.22 (brs, 2H, NH and OH), 3.45–3.57 (d, 1H, J ¼ 6 Hz), 3.56
(ddd, 1H, J ¼ 9.5, 6.6, 2.7 Hz), 6.78–6.82 (m, 3H), 7.24–7.41 (m, 2H); 13C
NMR (CDCl3, 100 MHz): d 23.27, 25.17, 25.67, 26.74, 29.63, 31.10, 60.02,
74.93, 115.11, 118.84, 129.35, 147.50; Mass (m/z) 220 (Mþ þ 1). Anal.
Calcd. for C14H21NO: C, 76.71; H, 9.59; N, 6.39. Found C, 76.82; H, 9.62; N,
6.28.
ACKNOWLEDGMENTS
We are thankful to the Director, IICT and Dr. J. S. Yadav for their
constant encouragement. NRS and TVG thank CSIR, New Delhi for providing
fellowships.
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733
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