1,1'-bis-methyl-3, 3-methylenebisimidazolium dichloride as an efficient phase transfer catalyst for ring opening of epoxides using SCN- and N 3- in water

Article abstract of DOI:10.3184/174751912X13371750612188

An efficient synthesis of β-azido alcohols and β-hydroxy thiocyanates has been achieved by ring opening of epoxides using 1,1'-bis-methyl-3, 3-methylene-bisimidazolium dichloride as a phase transfer catalyst at room temperature in water. The reaction is r

Full text of DOI:10.3184/174751912X13371750612188

396 RESEARCH PAPER
JULY, 396–397
JOURNAL OF CHEMICAL RESEARCH 2012
1,1′-Bis-methyl-3, 3-methylenebisimidazolium dichloride as an efficient
phase transfer catalyst for ring opening of epoxides using SCN– and
N3– in water
Soheil Sayyahia*, Hadis Mohammad Rezaeeb, Fatemeh Sharifat Khalfabadib and
Maryam Gorjizadehc
aDepartment of Chemistry, Mahshahr Branch, Islamic Azad University, Mahshahr 63519, Iran
bDepartment of Chemistry, Omidieh Branch, Islamic Azad University, Iran
cDepartment of Chemistry, Shushtar Branch, Islamic Azad University, Iran
An efficient synthesis of β-azido alcohols and β-hydroxy thiocyanates has been achieved by ring opening of epoxides
using 1,1′-bis-methyl-3, 3-methylene-bisimidazolium dichloride as a phase transfer catalyst at room temperature in
water. The reaction is regioselective and afforded the corresponding products in moderate to excellent yields.
Keywords: ionic liquid, ring opening reaction, β-azido-alcohols, β-hydroxy thiocyanates
In synthetic chemistry, ionic liquids (ILs) or molten salts are
an interesting group of chemicals, composed of anions and
cations, either of which may interact with solutes and therefore
significantly affect the outcome of reactions. They have
some special properties, such as low vapour pressure, ability to
dissolve a wide range of organic, inorganic and organometallic
compounds, thermal stability, non-flammability and wide
electrochemical stability.1–5
Phase transfer catalysts (PTC) are powerful reagents in
chemical transformations, the characteristics of which include
mild reaction conditions, safety, operational simplicity and
selectivity.6,7 One of the essential roles of classical PTC is to
transfer an inorganic reagent from the aqueous phase into the
organic phase, thus enabling the organic substrate to react with
the transferred ion and form the product in the organic phase
reaction. Recently, ILs have assumed this aspect as a phase
transfer or anion exchange catalyst.8–10
As a starting point, the ionic liquid 1,1′-bis-methyl-3,3-
methylene-bisimidazolium dichloride was synthesised by
microwave irradiation of 1-methylimidazole and dry dichloro-
methane under reflux condition for 15 min (Scheme 1).
This ionic liquid has been investigated for the ring opening
of a variety of epoxides with the N3 and SCN anions, giving
β-azido alcohols and β-hydroxy thiocyanates, respectively.
In order to evaluate catalytic activity of 1,1′-bis-methyl-3,
3-methylene-bisimidazolium dichloride, reactions between
styrene oxide and ammonium thiocyanate were carried out in
water at room temperature. The best results were obtained with
1 mmol of the epoxide, 3 mmol NH4SCN and 0.5 g of the ionic
liquid. Various aliphatic/aromatic epoxides have been used
as substrates to react under the optimised reaction condition.
The results are summarized in Table 1, which shows that the
ionic liquid operates effectively, with excellent yield for most
reactions. In all cases, a very clean reaction was observed and
careful examination of the 1H NMR spectra of the crude prod-
ucts clearly indicated the formation of only one regioisomer in
each case.
In continuing our efforts to develop and introduce new phase
transfer catalyst for organic transformation,11–14 we describe
heretheapplicationof1,1′-bis-methyl-3,3′-methylene-bisimid-
azolium dichloride as a PTC for ring opening of epoxides in
aqueous media.
In the 1H NMR spectra of cyclic epoxides such as cyclohex-
ene oxide, the coupling constant of the ring protons adjacent to
the –SCN and –OH groups clearly suggested their trans
configuration (3J12 = 15 Hz).
Results and discussion
It is generally accepted that the epoxide ring-opening reac-
tion proceeds under neutral or basic conditions via SN2 mecha-
nism giving inversion at the attacked C atom, generally the less
substituted one and furnishing 1,2- disubstituted products with
a trans or anti relationship of the nucleophile to the oxygen
leaving group (entries 2a–7b). In styrene oxide (entries 1a–1b),
the positive charge on the oxygen appears to be localised on
the more highly substituted benzylic carbon leading to the
major product.
It is noteworthy that no evidence for the formation of side-
product such as diol or thiirane was observed and the products
were obtained in pure form without further purification.
In summary, we have developed a novel, efficient and
regioselective ring opening of epoxides that with SCN− or N3−
Nucleophilic addition to epoxides plays a pivotal role in the
stereoselective preparation of 1,2-disubstituted products.15
Azido-alcohols are versatile intermediates in organic synthesis
since they are very important precursors of α-amino alcohols
and vicinal diamines in the chemistry of carbohydrates,
16,17
nucleosides, lactams, and oxazolines.
Thiocyanates are
also useful intermediates in agricultural, pharmaceutical and
synthetic chemistry.18,19 Unfortunately, some of the synthetic
methods available for the synthesis of azidohydrins or thiocya-
nohydrins suffer from disadvantages such as long reaction
times, use of volatile organic solvents and expensive
reagents, low regioselectivity and high temperature reaction
conditions.14,20,21
Scheme 1 Microwave-assisted synthesis of bisimidazolium ionic liquid.
* Correspondent. E-mail: sayyahi.soheil@gmail.com

JOURNAL OF CHEMICAL RESEARCH 2012 397
Table 1 Ring opening of epoxides with NH4SCN and NaN3
General experimental procedure
NH4SCN or NaN3 (3 mmol)was added to the suspension of an epoxide
(1mmol)and1, 1′-Bis-methyl-3, 3′-methylene-bisimidazoliumdichlo-
ride (0.5 g) in water (5.0 mL). The mixture was stirred at room tem-
perature for the time shown in Table 1. The reaction was monitored by
TLC (n-hexane: ethyl acetate; ratio=5:1). After the reaction was com-
plete, the product was extracted with EtOAc (3 × 10 mL). The organic
phase was collected and washed with water; dried over Na2SO4, and
evaporated in vacuo to give desired product.
Entry
Epoxide
Producta
X
Time Yield
/min /%b
2-Azido-2-phenyl-1-ethanol (1a): IR (νmax/cm−1): 3373 (OH), 2102
1
(N3). HNMR (400 MHz, CDCl3): δ = 3.37 (1H, s, OH), 3.74 (2H,
m, CH2), 4.65–4.69 (1H, m, CH), 7.34–7.44 (5H, m, ArH) ppm. 13C
NMR (100 MHz, CDCl3): δ = 66.37 (CHN3), 68.03 (CH2OH), 127.49
(m-CH), 128.46 (o-CH), 128.61 (p-CH), 136.47 (C) ppm.
1a
1b
N3
40
85
82
SCN 45
2-Hydroxy-1-phenylethyl thiocyannate (1b): IR (νmax/cm−1): 3419
(OH), 2151 (SCN); 1HNMR (400 MHz, CDCl3): δ = 4.15–4.32
(1H, m, CHSCN), 4.42 (1H, m, CH2), 4.62 (1H, m, CH2), 4.85 (1H,
s, OH), 7.32–7.52 (5H, m, ArH) ppm. 13C NMR (100 MHz, CDCl3):
δ = 46.34 (CH), 59.70 (CH2OH), 110.58 (SCN), 128.57 (m-CH),
129.83 (p-CH), 129.94 (o-CH), 137.43 (C) ppm.
2a
2b
N3
35
95
87
SCN 40
3a
3b
N3
30
92
80
3-Phenoxy-2-hydroxypropyl thiocyanate (2b): IR (νmax/cm−1): 3435
1
(OH), 2156 (SCN); HNMR (400 MHz, CDCl3): δ = 3.30 (2H, d,
SCN 60
CH2SCN), 3.78 (1H, s, OH), 4.15 (2H, d, OCH2), 4.29 (1H, m,
CHOH), 6.95 (2H, m, ArH), 7.02 (1H, m, ArH), 7.28 (2H, m, ArH)
ppm. 13C NMR (100 MHz, CDCl3): δ = 37.4 (CH2SCN), 68.1 (CHOH),
69.5 (OCH2), 113.0 (SCN), 114.6 (o-CH), 121.3 (p-CH), 129.9
(m-CH), 158.5 (C) ppm.
4a
4b
N3
10
87
85
SCN 15
3-Allyloxy-2-hydroxypropyl thiocyanate (3b): IR (νmax/cm−1): 3440
(OH), 2156 (SCN); 1H NMR (400 MHz, CDCl3): δ = 3.04–3.24 (3H,
m, OH, CH2SCN), 3.53 (2H, d, OCH2), 4.05 (3H, m, OCH2CHOH),
5.19–5.29 (2H, m, =CH2), 5.87 (1H, m, =CH) ppm. 13C NMR
(100 MHz, CDCl3): δ = 37.3 (CH2SCN), 69.2 (CH2O), 71.1 (CHOH),
71.6 (OCH2), 113.1 (SCN), 117.5 (CH2=), 133.7 (=CH) ppm.
1-Azido-3-butoxypropan-2-ol (5a): IR (νmax/cm−1): 3445 (OH), 2102
5a
5b
N3
15
96
80
SCN 65
6a
6b
N3
20
80
90
SCN 15
1
(N3); HNMR (400 MHz, CDCl3): δ = 0.87 (3H, t, CH3), 1.31–1.35
(2H, m, CH2), 1.50–1.53 (2H, m, CH2), 3.14 (1H, s, OH), 3.30–3.32
(2H, m, CH2N3), 3.39–3.44 (4H, m, CH2OCH2), 3.87 (1H, m, CHOH)
ppm. 13C NMR (100 MHz, CDCl3): δ = 13.78 (CH3), 19.16 (CH2),
30.74 (CH2), 53.52 (CH2N3), 69.74 (CH2O), 70.59 (CHOH), 70.71
(OCH2CH) ppm.
7a
7b
N3
20
80
82
SCN 50
a Products were identified by comparison of their physical and
spectroscopic data with those of authentic samples.11,19,21–23
bIsolated yields.
Received 6 March 2012; accepted 16 April 2012
Paper 1201200 doi: 10.3184/174751912X13371750612188
Published online: 26 June 2012
as nucleophiles in the presence of 1,1′-bis-methyl-3, 3′-methy-
lenebisimidazolium dichloride. Shorter reaction times, sim-
plicity in operation, the low cost of reagents and high yields of
products can be considered as an advantage of this method.
References
1
N. Jain, A. Kumar, S. Chauhan and S.M.S. Chauhan, Tetrahedron, 2005,
61, 1015.
2
3
J. Dupont, R.F. de Souza and P.A.Z. Suarez, Chem. Rev., 2002, 102, 3667.
M. Petkovic, K.R. Seddon, L.P.N. Rebelo and C.S. Pereira, Chem. Soc.
Rev., 2011, 40, 1383.
Experimental
Chemical were purchased fromAldrich and Merck Chemical compan-
ies and used without further purification. The synthesis of the IL was
carried out in a microwave oven with a 2500 W power (MicroSynth,
Milestone) equiped with a condenser. Products were characterised by
comparison of their physical data, IR and 1H NMR spectra with known
samples. NMR spectra were recorded in CDCl3 or DMSO on a Bruker
Advance DPX 400 MHz instrument spectrometer using TMS as an
internal standard. IR spectra were recorded on a BOMEM MB-Series
1998 FT-IR spectrometer. The purity of the products and reaction
monitoring were followed by TLC on silica gel polygram SILG/UV
254 plates.
4
5
6
N.L. Lancaster, J. Chem. Res., 2005, 413.
N.V. Plechkova and K.R. Seddon, Chem. Soc. Rev., 2008, 37, 123.
C.M. Starks, C.L. Liotta and M.E. Halpern, Phase-transfer catalysis,
Chapman & Hall, NewYork, 1994.
T. Ooi, K. Maruoka, Angew. Chem. Int. Ed. 2007, 46, 4222.
S. Muthusamy and B. Gnanaprakasam, Tetrahedron Lett., 2005, 46, 635.
S. Okamoto, K. Takano, T. Ishikawa, S. Ishigami and A. Tsuhako,
Tetrahedron Lett., 2006, 47, 8055.
7
8
9
10 H. Olivier-Bourbigou, L. Magna and D. Morvan, Appl. Catal. A., 2010,
373, 1.
11 A.R. Kiasat, R. Badri, B. Zargar and S. Sayyahi, J. Org. Chem., 2008, 73,
8382.
12 M. Gorjizadeh and S. Sayyahi, Chin. Chem. Let., 2011, 22, 300.
13 A.R. Kiasat and S. Sayyahi, Catal. Commun., 2010, 11, 484.
14 S. Sayyahi and J. Saghanezhad, Chin. Chem. Let., 2011, 22, 300.
15 S. Bonollo, D. Lanari and L. Vaccaro, Eur. J. Org. Chem., 2011, 2587.
16 G. Sabitha, R.S. Babu, M. Rajkumar and J.S. Yadav, Org. Lett., 2002, 4,
343.
17 A.R. Kiasat and M. Zayadi, Catal. Commun., 2008, 9, 2063.
18 J.S. Yadav, B.V.S. Reddy and C.S. Reddy, Tetrahedron Lett., 2004, 45,
1291.
Synthesis of 1,1′-bis-methyl-3, 3-methylenebisimidazolium dichloride
A mixture of 1-methylimidazole (0.06 mol, 5.0 g) and dichlorometh-
ane (0.03 mol, 2.54 g) was placed in a 50 mL round-bottomed flask
equipped with a magnetic stirrer and subjected to microwave irradia-
tion (200W) under reflux condition for 15 minutes. After cooling
to room temperature, the precipitate was filtered off and washed
twice with 10 mL of dry THF. After drying for 12 h under vacuum at
80 °C, the expected ionic liquid was obtained as white solid; Yield
19 A.R. Kiasat and M. Fallah-Mehrjardi, J. Braz. Chem. Soc., 2008, 19,
1595.
1
20 A.R. Kiasat and M. Fallah-Mehrjardi, Catal. Commun., 2008, 9, 1497.
21 R. Eisavi, B. Zeynizadeh and M.M. Baradaran, Bull. Korean Chem. Soc.,
2011, 32, 630.
22 B. Das, V.S. Reddy, M. Krishnaiah and Y.K. Rao, J. Mol. Catal, A: Chem.,
2007, 270, 89.
23 S.-W. Chen, S.S. Thakur, W. Li, C.-K. Shin, R.B. Kawthekar and
G.-J. Kim, J. Mol. Catal, A: Chem., 2006, 259, 116.
48%; m.p. 73–75 ºC; H NMR (400 MHz, DMSO-d6, 25 ºC): δ 3.90
(6H, s, 2NCH3), 6.86 (2H, s, NCH2), 7.81 (2H, s, 2NCH), 8.22 (2H, s,
2NCH), 9.80 (2H, s, 2NCHN) ppm. 13C NMR (100 MHz, DMSO-d6,
25 ºC): δ 36.65 (NCH3), 58.04 (NCH2N), 122.49 (NCH), 124.64
(NCH) 138.62 (NCHN) ppm. Analyses: Calcd for C9H14Cl2N4: C,
43.39; H, 5.66; N, 22.49. Found: C, 43.27; H, 5.70; N, 22.61%.

Copyright of Journal of Chemical Research is the property of Science Reviews 2000 Ltd. and its content may
not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written
permission. However, users may print, download, or email articles for individual use.