Catalyst-free, direct, high regio-, and chemoselective conversion of epoxides to 2-thiocyanatoalkyl alkanoates under neutral and solvent-free conditions

Article abstract of DOI:10.1139/V10-052

A catalyst-free, direct, high regio-, and chemo-selective method is reported for the facile conversion of a wide variety of epoxides to their corresponding 2-thiocyanatoalkyl alkanoates, which contain two important functional groups (ester and thiocyanate), using a mixture of tetrabutylammonium rhodanide ((n-Bu)4NSCN) and an aliphatic or aromatic carboxylic anhydride under neutral and solvent-free conditions.

Full text of DOI:10.1139/V10-052

598
Catalyst-free, direct, high regio-, and chemo-
selective conversion of epoxides to
2-thiocyanatoalkyl alkanoates under neutral and
solvent-free conditions
Ghasem Aghapour and Razieh Hatefipour
Abstract: A catalyst-free, direct, high regio-, and chemo-selective method is reported for the facile conversion of a wide
variety of epoxides to their corresponding 2-thiocyanatoalkyl alkanoates, which contain two important functional groups
(ester and thiocyanate), using a mixture of tetrabutylammonium rhodanide ((n-Bu)4NSCN) and an aliphatic or aromatic
carboxylic anhydride under neutral and solvent-free conditions.
Key words: epoxide, 2-thiocyanatoalkyl alkanoate, carboxylic anhydride, tetrabutylammonium rhodanide.
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Resume : On a mis au point une methode hautement regio- et chimio-selective directe et n’impliquant aucun catalyseur
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pour la transformation facile d’une grande variete d’epoxydes en alcanoates de 2-thiocyanatoalkyles correspondants qui
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contiennent deux groupes fonctionnels importants (ester et thiocyanate); elle comporte l’utilisation d’une melange de rho-
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danide de tetrabutylammonium (n-Bu)4NSCN et l’anhydride d’un acide carboxylique aliphatique ou aromatique, dans des
conditions neutres et sans solvant.
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Mots-cles : epoxyde, alcanoate de 2-thiocyanatoalkyle, anhydride d’acide carboxylique, rhodanide de tetrabutylammonium.
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[Traduit par la Redaction]
is routinely carried out by acid anhydrides or acid chlorides
in the presence of tertiary amines,11 protic or Lewis acids,12
or sometimes solid acid catalysts.13 Also, many other differ-
ent reagents or catalysts have been introduced in various
conditions for the esterification reactions.10
It is obvious that with respect to the importance of thio-
cyanato and ester functional groups, 2-thiocyanatoalkyl alka-
noates, which contain both these groups, represent an
interesting and important subclass and have multiple modes
of reactivity. Although, there are several reports concerning
the preparation of b-hydroxy thiocyanates from epoxides us-
ing different reagents or catalysts,14–16 as far as we know,
there is no report in the literature about the direct synthesis
of 2-thiocyanatoalkyl alkanoates from epoxides. Even the re-
ports on the stepwise conversion of epoxides to 2-thiocyana-
toalkyl alkanoates are scarce.
Introduction
Epoxides are important intermediates in organic synthe-
sis.1 Their facile regio- and stereo-selective ring-opening re-
actions with a wide variety of nucleophiles provide a
powerful strategy in organic chemistry.1–6 However, in most
of the epoxide ring-opening reactions under acidic condi-
tions, the formation of a mixture of regioisomers and poly-
merization is observed.
On the other hand, thiocyanates have gained considerable
importance in various areas of organosulfur chemistry.7 For
example, these compounds are important intermediates in
agricultural and pharmaceutical chemistry: the thiocyanato
group occurs as an important functionality in certain anti-
cancer natural products formed by deglycosylation of gluco-
sinolates derived from cruciferous vegetables.8,9
Also, synthesis of esters has played an important role in
organic synthesis from its infancy.10 This importance
stemmed from its utility in diverse fields both in the labora-
tory and in industry. Ester moieties, irrespective of whether
acyclic or cyclic, constitute major backbones, as well as
functional groups of chemical significance, in numerous nat-
ural products and synthetic compounds. Ester groups also
play versatile temporary roles in organic synthesis for the
protection of carboxylic acids and hydroxy groups. There-
fore, the acetylation of alcohols is one of the most widely
used procedure for the protection of hydroxy groups, which
In one method, epoxide was first converted to its corre-
sponding b-hydroxy thiocyanate using NH4SCN in the pres-
ence of 18-crown-6, followed by
a treatment with
acetylchloride in reflux conditions to convert the hydroxy
group into an ester group.17 A second method involves the
reaction of triphenylphosphine-thiocyanogen (TPPT) with
epoxide at –40 8C under argon and then at room temperature
overnight. Then, in the second step, the resulted b-hydroxy
thiocyanate was treated with benzoyl chloride and triethyl-
amine producing the final desired product.15b In addition, in
Received 2 November 2009. Accepted 25 March 2010. Published on the NRC Research Press Web site at canjchem.nrc.ca on 27 May
2010.
G. Aghapour1 and R. Hatefipour. School of Chemistry, Damghan University of Basic Sciences, Damghan, 36715-364, Iran.
1Corresponding author (e-mail: Gh_Aghapour@dubs.ac.ir).
Can. J. Chem. 88: 598–604 (2010)
doi:10.1139/V10-052
Published by NRC Research Press

Aghapour and Hatefipour
599
Scheme 1. Direct and catalyst-free method for the conversion of
epoxides to 2-thiocyanatoalkyl alkanoates using tetrabutylammo-
nium rhoanide ((n-Bu)4NSCN) in the presence of an aliphatic or
aromatic carboxylic anhydride under neutral and solvent-free con-
ditions.
a different work for obtaining of these compounds, epoxides
were treated with thiocyanic acid as described by van Tame-
len,14a producing b-hydroxy thiocyanates, which on treat-
ment with acetyl chloride in pyridine gave the
corresponding 2-thiocyanatoalkyl alkanoates.18 Furthermore,
in this report, the formation of these compounds has also
been described via treatment of thiocyanogen chloride with
alkenes in the presence of a radical inhibitor in acetic acid
in the dark as minor products.18
On the other hand, waste prevention and environmental
protection are major requirements in an overcrowded world
with increasing demands. Synthetic chemistry continues to
develop various techniques for obtaining better products
with less environmental impact. One of the more promising
approaches is solvent-free organic synthesis.19 These reac-
tions have many advantages: reduced pollution, low costs,
and simplicity in process and handling. These factors are es-
pecially important in industry.20
Thus, on the basis of the above descriptions, the develop-
ment of simple and efficient methods for the preparation of
2-thiocyanatoalkyl alkanoates from epoxides, especially in
neutral and solvent-free conditions, is desirable.
As shown in Table 2, epoxides are directly and efficiently
converted to 2-thiocyanatoalkyl acetates by a mixture of (n-
Bu)4NSCN:(CH3CO)2O in a 1.2:0.5 molar ratio at 60 8C
under neutral and solvent-free conditions and without using
a catalyst.
It is possible to obtain other 2-thiocyanatoalkyl alkanoates
using another carboxylic anhydride in this method. We
found that epoxides can be converted to 2-thiocyanatoalkyl
benzoates by using benzoic anhydride as an aromatic anhy-
dride instead of acetic anhydride (Table 2, entries 8 and 9).
However, benzoic anhydride (0.85 equiv.) must be used
slightly more than acetic anhydride (0.5 equiv.), probably
due to its lower reactivity compared to acetic anhydride.
Except for the case of styrene oxide, which produced two
regioisomers (Table 2, entry 2), the reaction of other unsym-
metrical epoxides occurred with high regioselectivity, and
the thiocyanate anion attacked the less-hindered side of the
epoxide ring due to the combination of steric and electronic
factors. Under these reaction conditions, the ethereal bonds,
phenyl ring, carbon–halogen bonds, and carbon–carbon dou-
ble bonds as functional groups that are present in the epox-
ide molecules remain intact.
In order to have more insight into the applicability, selec-
tivity, and limitations of the present method, we studied the
possibility of the conversion of epoxides to 2-thiocyana-
toalkyl alkanoates in the presence of some other functional
groups in binary mixtures. For this purpose, a binary mix-
ture of glycidyl phenyl ether and another organic compound
(1:1) was treated with a stirring mixture of (n-Bu)4NSCN
(1.2 equiv) and (CH3CO)2O (0.5 equiv) in a flask at 60 8C
under solvent-free conditions. The conversion yields ob-
tained for these selective reactions of different binary mix-
tures are shown in Scheme 2.
Results and discussion
In our previous works,21 we have reported the conversion
of epoxides to b-halohydrins and now in continuation of our
recent work22 on the catalyst-free conversion of epoxides to
b-hydroxy thiocyanates and also with consideration of ad-
vantages of solvent-free reactions, we report a direct and
catalyst-free method for the conversion of epoxides to 2-thi-
ocyanatoalkyl alkanoates using a mixture of tetrabutylam-
monium rhodanide ((n-Bu)4NSCN) and an aliphatic or
aromatic carboxylic anhydride under neutral and solvent-
free conditions (Scheme 1).
First, we took 1,2-epoxytetradecane as an example, and
optimized the reaction conditions for its conversion to 1-do-
decyl-2-thiocyanatoethyl acetate (1) using thiocyanate anion
in the presence of acetic anhydride (Ac2O). We found that
no desired product (1) was formed using NH4SCN as a
source of thiocyanate anion in various conditions. Thus, we
tried to perform this conversion using (n-Bu)4NSCN. The re-
sults are shown in Table 1. It must be noted that in all of
these reactions epoxide was added to a stirring mixture of
(n-Bu)4NSCN and acetic anhydride in the absence of a cata-
lyst and stirring was continued for stated times.
As shown in Table 1, this reaction was unsuccessful in
CH2Cl2 and CH3CN as solvents even under reflux conditions
(Table 1, entries 1–3). Also, 1 was obtained in only 30%–
40 % yield at room temperature after 24 h under solvent-
free conditions (Table 1, entries 4 and 5). However, the
yield of this reaction was increased by increasing the reac-
tion temperature (60 8C) under solvent-free conditions
(Table 1, entry 6). Finally, the best result was obtained in
the case of entry 7 (Table 1) so that 1 was produced in
80 % yield using a mixture of (n-Bu)4NSCN:(CH3CO)2O in
a 1.2 :0.5 molar ratio at 60 8C after 6 h under solvent-free
conditions.
In addition to the various selectivities mentioned above,
as shown in Scheme 2, epoxides can be efficiently converted
to their corresponding 2-thiocyanatoalkyl alkanoates in the
presence of alcohols, carboxylic acids, aldehydes, amines,
thiols, esters, and amides with excellent selectivity using
the present method so that these functional groups remain
completely intact.
Conclusion
In conclusion, the present investigation has demonstrated
that the use of tetrabutylammonium rhodanide ((n-
Bu)4NSCN) in the presence of aliphatic or aromatic carbox-
ylic anhydrides offers a direct, simple, and efficient method,
avoiding the use of a catalyst for the regioselective conver-
sion of a wide variety of epoxides to their corresponding 2-
thiocyanatoalkyl alkanoates, which have two important func-
We therefore used these conditions (Table 1, entry 7) for
the conversion of other epoxides to their corresponding 2-
thiocyanatoalkyl acetates. The results are shown in Table 2.
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Can. J. Chem. Vol. 88, 2010
Scheme 2. Chemoselectivities in the reaction of 2,3-epoxypropyl
phenyl ether with (n-Bu)4NSCN in the presence of acetic anhydride
at 60 8C under neutral and solvent-free conditions.
Experimental
Solvents, reagents, and chemicals were obtained from
Merck (Germany) and Fluka (Switzerland) Chemical Com-
panies. Some products are known compounds and data of
these compounds (such as bp, mp, H and 13C NMR, IR,
1
mass) have been found to be identical to those reported.17,18
Also, other products were characterized by their physical or
spectral data. FTIR spectra were recorded on a PerkinElmer
RXI spectrophotometer. Nuclear magnetic resonance spectra
were recorded on a Brucker Avance DRX-500 spectrometer.
Mass spectra were determined on a HP 5973 msd at 70 eV.
Thin layer chromatography (TLC) was carried out on silica
gel 254 analytical sheets obtained from Fluka.
Typical procedure for the conversion of 2,3-epoxypropyl
phenyl ether to 1-phenoxy-3-thiocyanatopropan-2-yl
acetate (7) using (n-Bu)4NSCN in the presence of acetic
anhydride
Acetic anhydride (0.047 mL, 0.5 mmol) was added to a
flask containing tetrabutylammonium rhodanide (0.36 g,
1.2 mmol) in an oil bath at 60 8C under solvent-free condi-
tions. This mixture was stirred for 15 min so that a homoge-
neous mixture was formed. Then 2,3-epoxypropyl phenyl
ether (0.135 mL, 1 mmol) was added and the reaction mix-
ture was stirred until TLC showed the completion of the re-
action (2.5 h). The crude product was subjected to column
chromatography on silica gel using n-hexane-ethyl acetate
(60:1) as eluent affording 7 (0.226 g, 90% yield). Oil. FTIR
(neat, cm–1): 2157 (m, CN), 1743 (s, C=O). 1H NMR
(CDCl3, 500 MHz, ppm) d: 2.15 (s, 3H (CH3)), 3.30–3.35
(dd, 1H (CHCHaHbS), JHaHb = 14.2 Hz, JHaCH = 6.7 Hz),
3.40–3.43 (dd, 1H (CHCHaHbS), JHbCH = 4.3 Hz), 4.12–
4.16 (dd, 1H (OCHcHdCH), JHcHd = 10.2 Hz, JHcCH = 5.8
Hz), 4.17–4.20 (dd, 1H (OCHcHdCH), JHdCH = 4.5 Hz),
5.40–5.44 (m, 1H (CH)), 6.89–6.91 (m, 2H (Ph)), 6.95–7.01
(m, 1H (Ph)), 7.26–7.32 (m, 2H (Ph)). 13C NMR (CDCl3,
125.77 MHz, ppm) d: 21.17, 34.83, 66.83, 70.56, 112.15,
114.99, 122.19, 130.07, 158.28, 170.49. Mass spectra m/z:
251 (M, 3%), 208 (M – CH3CO, 0.3%), 193 (M – SCN,
0.37%), 158 (M – PhO, 100%), 43 (CH3CO, 43%).
Spectroscopic data
1-Phenyl-2-thiocyanatoethyl acetate (2)
1
Oil. FTIR (neat, cm–1): 2156 (m, CN), 1744 (s, C=O). H
NMR (CDCl3, 500 MHz, ppm) d: 2.17 (s, 3H (CH3)), 3.28–
3.31 (dd, 1H (CHaHb), JHaHb = 14 Hz, JHaCH = 4.4 Hz),
3.34–3.39 (dd, 1H(CHaHb), JHbCH = 8.1 Hz), 6.02–6.05
(m, 1H (CH)), 7.32–7.41 (m, 5H (Ph)). 13C NMR (CDCl3,
125.77 MHz, ppm) d: 21.30, 39.51, 74.24, 112.05, 126.82,
129.40, 129.59, 137.57, 170.15. Mass spectra m/z: 221 (M,
0.31%), 178 (M – CH3CO, 0.21%), 161 (M – CH3CO2H,
10.6%), 149 (M – CH2SCN, 64%), 107 (M – CH2SCN –
CH2CO, 100%), 43 (CH3CO, 72.96%).
tional groups (ester and thiocyanate) under solvent-free con-
ditions. This method can be efficiently used for preparation
of 2-thiocyanatoalkyl alkanoates even in the presence of
many other functional groups with excellent chemoselectiv-
ity. Easy work up and operation under neutral and solvent-
free conditions without using a catalyst are considered other
advantages of this method.
2-Phenyl-2-thiocyanatoethyl acetate (3)
1
Oil. FTIR (neat, cm–1): 2156 (m, CN), 1744 (s, C=O). H
NMR (CDCl3, 500 MHz, ppm) d: 2.11 (s, 3H (CH3)), 4.26–
4.30 (dd, 1H (CHaHb), JHaHb = 11.9 Hz, JHaCH = 8.04 Hz),
4.32–4.35 (dd, 1H (CHaHb), JHbCH = 3.9 Hz), 4.58–4.62
(m, 1H (CH)), 7.32–7.41 (m, 5H (Ph)). 13C NMR (CDCl3,
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Aghapour and Hatefipour
601
Table 1. Conversion of 1,2-epoxytetradecane to 1-dodecyl-2-thiocyanatoethyl acetate (1) using
(n-Bu)4NSCN/Ac2O in various conditions.
Entry
Solvent
CH2Cl2
CH2Cl2
CH3CN
—
—
—
—
—
Molar ratioa
1:1.2:1
1:1.2:1
1:1.2:1
1:1.2:2
1:1.2:0.5
1:1.2:1
1:1.2:0.5
1:1.2:0.25
Temperature (8C)
RT
Reflux
Reflux
RT
RT
60
60
60
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
46
46
46
24
24
5.5
6
10
10
20
40
30
78
80
20
6
aThe molar ratio is related to epoxide:(n-Bu)4NSCN:Ac2O.
125.77 MHz, ppm) d: 21.19, 51.86, 65.93, 111.08, 127.13,
129.08, 129.79, 136.94, 170.48. Mass spectra m/z: 221 (M,
0.15%), 163 (M– SCN, 54.44%), 104 (M– SCN – CH3CO2,
31.84%), 43 (CH3CO, 100%).
ppm) d: 1.31–1.43 (m, 3H (ring), 1.63–1.71 (m, 1H (ring)),
1.79–1.85 (m, 2H (ring)), 2.10 (s, 3H (CH3)), 2.15–2.17 (m,
1H (ring)), 2.27–2.31 (m, 1H (ring)), 3.17–3.22 (m, 1H
(CHS)), 4.74–4.79 (m, 1H (CHO)). 13C NMR (CDCl3,
125.77 MHz, ppm) d: 21.36, 24.03, 25.98, 32.60, 32.86,
51.74, 75.06, 111.21, 170.44. Mass spectra m/z: 199 (M,
0.22%), 156 (M – CH3CO, 2.87%), 139 (M – CH3CO2H,
94.98%), 81 (M – CH3CO2H – SCN, 81.87%), 43 (CH3CO,
100%).
1-Isopropyloxy-3-thiocyanatopropan-2-yl acetate (4)
1
Oil. FTIR (neat, cm–1): 2156 (m, CN), 1743 (s, C=O). H
NMR (CDCl3, 500 MHz, ppm): d: 1.13–1.14 (d, 6H (2 Â
CH3), JCH 3CH = 6.1 Hz), 2.12 (s, 3H (CH3)), 3.18–3.22 (dd,
1H (CHCHaHbS), JHaHb = 14 Hz, JHaCH = 6.3 Hz), 3.31–
3.35 (dd, 1H (CHCHaHbS), JHbCH = 4.2 Hz), 3.51–3.62 (m,
1H ((CH3)2CHO) + 2H (OCH2CH)), 5.14–5.19 (m, 1H
(CHOC=O). 13C NMR (CDCl3, 125.77 MHz, ppm) d:
21.22, 22.37, 35.11, 66.92, 71.22, 73.06, 112.52, 170.55.
Mass spectra m/z: 217 (M, 0.35%), 174 (M – CH3CO,
0.23%), 159 (M – SCN, 3.03%), 158 (M – (CH3)2CHO or
M – CH3CO2, 29.99%), 99 (M – (CH3)2CHO – HSCN,
31.82%), 43 (CH3CO, 100%). Anal. calcd. for C9H15NO3S:
C 49.75, H 6.96, N 6.45; found: C 49.87, H 6.91, N 6.51.
1-Dodecyl-2-thiocyanatoethyl acetate (1)
1
Oil. FTIR (neat, cm–1): 2158 (m, CN), 1745 (s, C=O). H
NMR (CDCl3, 500 MHz, ppm) d: 0.86–0.88 (t, 3H
(CH3CH2), J = 7.06 Hz), 1.25–1.30 (m, 20H (10 Â CH2)),
1.59–1.65 (m, 1H (CHaHbCH)), 1.69–1.74 (m, 1H
(CHaHbCH)), 2.11 (s, 3H (CH3CO)), 3.04–3.08 (dd,
1H(CHCHaHbS), JHaHb = 13.93 Hz, JHaCH = 6.55 Hz),
3.22–3.26 (dd, 1H (CHCHaHbS), JHbCH = 3.83 Hz), 5.04–
5.13 (m, 1H (CH)). 13C NMR (CDCl3, 125.77 MHz, ppm)
d: 14.51, 21.26, 23.09, 25.50, 29.65, 29.75, 29.79, 29.83,
29.90, 29.93, 30.04, 32.32, 33.23, 38.00, 72.29, 112.43,
170.82. Mass spectra m/z: 313 (M, 0.32%), 255 (M – SCN,
1.5%), 253 (M – CH3CO2H, 4.5%), 196 (M – SCN –
CH3CO2, 6.06%), 43 (CH3CO, 100%). Anal. calcd. for
C17H31NO2S: C 65.13, H 9.97, N 4.47; found: C 65.09, H
10.02, N 4.45.
1-Allyloxy-3-thiocyanatopropan-2-yl acetate (5)
1
Oil. FTIR (neat, cm–1): 2157 (m, CN), 1747 (s, C=O). H
NMR (CDCl3, 500 MHz, ppm) d: 2.13 (s, 3H (CH3)), 3.19–
3.23 (dd, 1H(CHCHaHbS), JHaHb = 14 Hz, JHaCH = 6.4
Hz), 3.31–3.35 (dd, 1H (CHCHaHbS), JHbCH = 4.4 Hz),
3.58–3.66 (m, 2H (OCH2)), 4.00–4.02 (m, 2H (CH2O)),
5.20–5.29 (m, 1H (CH) + 2H (CH2=)), 5.82–5.90 (m, 1H
(=CH)). 13C NMR (CDCl3, 125.77 MHz, ppm) d: 21.22,
34.92, 68.82, 70.97, 72.86, 112.35, 118.35, 134.25, 170.52.
Mass spectra m/z: 215 (M, 0.36%), 172 (M – CH3CO,
2.94%), 158 (M – C3H5O, 78.92%), 115 (M – C3H5O –
CH3CO, 4.4%), 100 (M – C3H5O – SCN, 4.5%), 98 (M –
C3H5O – CH3CO2H, 7.3%), 43 (CH3CO, 100%). Anal.
calcd. for C9H13NO3S: C 50.21, H 6.09, N 6.51; found: C
50.29, H 6.14, N 6.45.
1-Chloro-3-thiocyanatopropan-2-yl acetate (8)
1
Oil. FTIR (neat, cm–1): 2159 (m, CN), 1747 (s, C=O). H
NMR (CDCl3, 500 MHz, ppm) d: 2.12 (s, 3H (CH3)), 2.99–
3.05 (m, 2H (CH2S)), 3.75–3.77 (m, 2H (ClCH2)), 5.26–5.31
(m, 1H (CH)). 13C NMR (CDCl3, 125.77 MHz, ppm) d:
21.28, 34.87, 43.29, 71.48, 112.12, 170.54. Mass spectra m/
z: 195 (M + 2, 0.17%), 193 (M, 0.5%), 135 (M + 2 –
CH3CO2H or M – SCN, 5.86%), 133 (M – CH3CO2H,
16.51%), 98 (M + 2 – CH3CO2H – 37Cl or M – CH3CO2H –
35Cl, 12.72%), 77 (M + 2 – CH3CO2H – SCN, 3.03%), 75
(M – CH3CO2H – SCN, 9.33%), 43 (CH3CO, 100%). Anal.
calcd. for C6H8NO2SCl: C 37.21, H 4.16, N 7.23; found: C
37.10, H 4.19, N 7.25.
trans-2-Thiocyanatocyclohexyl acetate (6)
Bp 101–102 8C/0.2 mmHg (1 mmHg = 133.322 Pa) (lit.
value18 bp 102–103 8C/0.2 mmHg). FTIR (neat, cm–1):
1
2153 (s, CN), 1741 (s, C=O). H NMR (CDCl3, 500 MHz,
Published by NRC Research Press

602
Can. J. Chem. Vol. 88, 2010
Table 2. Catalyst-free conversion of epoxides to 2-thiocyanatoalkyl alkanoates
using (n-Bu)4NSCN (1.2 equiv.)/carboxylic anhydride at 60 8C under neutral and
solvent-free conditions.
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Aghapour and Hatefipour
603
(4) Bonini, C. R.; Righi, G. Synthesis 1994, 225–238. doi:10.
1055/s-1994-25445.
(5) Gorzynski Smith, J. Synthesis 1984, 629–656. doi:10.1055/s-
1984-30921.
1-Allyloxy-3-thiocyanatopropan-2-yl benzoate (9)
Oil. FTIR (neat, cm–1): 2157 (m, CN), 1722 (s, C=O),
1
1601 (m, Ph). H NMR (CDCl3, 500 MHz, ppm) d: 3.38–
3.42 (dd, 1H (CHCHaHbS), JHaHb = 14 Hz, JHaCH = 6.3
Hz), 3.46–3.50 (dd, 1H (CHCHaHbS), JHbCH = 4.5 Hz),
3.73–3.76 (dd, 1H (OCHcHdCH), JHcHd = 10.4 Hz, JHcCH =
5.8 Hz), 3.78–3.81 (dd, 1H (OCHcHdCH), JHdCH = 4.4 Hz),
4.04–4.06 (m, 2H (CH2O)), 5.20–5.22 (dd, 1H (HaHbC=CH),
JHaCH = 10.36 Hz, JHaHb = 1.2 Hz), 5.26–5.30 (dd, 1H
(HaHbC=CH), JHbCH = 17 Hz), 5.45–5.49 (m, 1H (CH)),
5.84–5.92 (m, 1H (=CH)), 7.44–7.48 (m, 2H (Ph)), 7.57–
7.60 (m, 1H (Ph)), 8.06–8.09 (m, 2H (Ph)). 13C NMR
(CDCl3, 125.77 MHz, ppm) d: 35.35, 68.81, 71.41, 72.91,
112.47, 118.35, 128.95, 129.56, 130.39, 134.01, 134.31,
166.02. Mass spectra m/z: 277 (M, 0.3%), 220 (M – C3H5O,
51.72%), 162 (M – C3H5O – SCN, 1.4%), 105 (PhCO,
100%). Anal. calcd. for C14H15NO3S: C 60.63, H 5.45, N
5.05; found: C 60.69, H 5.48, N 5.02.
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80704-8.
(7) Guy, R. G. The Chemistry of the Cyanates and Their Thio
Derivatives; Patai, S., Ed.; Wiley Interscience: New York,
1977; p 819.
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1-Isopropyloxy-3-thiocyanatopropan-2-yl benzoate (10)
Oil. FTIR (neat, cm–1): 3020 (w, Ph-H), 2157 (m, CN),
1723 (s, C=O), 1601 (w, C=C). 1H NMR (CDCl3, 500
MHz, ppm) d: 1.16–1.17 (d, 6H (2 Â CH3), JCH3CH = 6.1
Hz), 3.37–3.41 (dd, 1H (CHCHaHbS), JHaHb = 13.95 Hz,
JH aCH = 6.2 Hz), 3.47–3.51 (dd, 1H (CHCHaHbS), JHbCH =
4.3 Hz), 3.62–3.67 (m, 1H ((CH3)CHO)), 3.68–3.71 (dd, 1H
(OCHcHdCH), JHcHd = 10.1 Hz, JHcCH = 6.46 Hz), 3.76–
3.79 (dd, 1H (OCHcHdCH), JHdCH = 4.42 Hz), 5.41–5.44
(m, 1H (CH)), 7.44–7.48 (m, 2H (Ph)), 7.57–7.60 (m, 1H
(Ph)), 8.07–8.09 (m, 2H (Ph)). 13C NMR (CDCl3, 125.77
MHz, ppm) d: 22.39, 35.57, 66.91, 71.64, 73.16, 112.66,
128.94, 129.65, 130.37, 133.96, 166.07. Mass spectra m/z:
279 (M, 0.2%), 220 (M – C3H7O, 15.5%), 162 (M –
C3H7O – SCN, 0.8%), 105 (PhCO, 100%). Anal. calcd. for
C14H17NO3S: C 60.19, H 6.13, N 5.02; found: C 60.12, H
6.09, N 5.10.
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Takhi, M. Tetrahedron Lett. 1998, 39 (20), 3263–3266.
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1-(4-Chlorophenoxy)-3-thiocyanatopropan-2-yl acetate (11)
Mp 44–45 8C (lit. value17 mp 43–44 8C). FTIR (neat,
1
cm–1): 2156 (m, CN), 1743 (s, C=O). H NMR (CDCl3, 500
MHz, ppm) d: 2.15 (s, 3H (CH3)), 3.30–3.34 (dd, 1H
(CHCHaHbS), JHaHb = 13.9 Hz, JHaCH = 6.4 Hz), 3.41–
3.44 (dd, 1H (CHCHaHbS), JHbCH = 4.3 Hz), 4.11–4.14
(dd, 1H (OCHcHdCH), JHcHd = 10.3 Hz, JHcCH = 5.5 Hz),
4.17–4.20 (dd, 1H (OCHcHdCH), JHdCH = 4.4 Hz), 5.40–
5.43 (m, 1H (CH)), 6.85–7.33 (m, 4H (ph)). 13C NMR
(CDCl3, 125.77 MHz, ppm) d: 20.66, 34.19, 66.57, 69.84,
111.57, 115.74, 126.60, 129.42, 156.32, 169.98.
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Acknowledgements
We gratefully acknowledge the support of this work by the
Damghan University of Basic Sciences Research Council.
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