Catalysis by ionic liquids: Significant rate acceleration with the use of [pmIm]Br in the three-component synthesis of dithiocarbamates

Article abstract of DOI:10.1002/ejoc.200700842

An easily accessible neutral ionic liquid, 1-methyl-3-pentylimidazolium bromide, promoted a one-pot three-component condensation of an amine, carbon disulfide, and an activated alkene/dichloromethane/epoxide to produce the corresponding dithiocarbamates in high yields at room temperature. The reactions are very fast in ionic liquids relative to those in other reaction media. These reactions do not require any additional catalyst or solvent. The ionic liquid can be recovered and recycled for subsequent reactions. A plausible mechanism is suggested. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejoc.200700842

FULL PAPER
DOI: 10.1002/ejoc.200700842
Catalysis by Ionic Liquids: Significant Rate Acceleration with the Use of
[pmIm]Br in the Three-Component Synthesis of Dithiocarbamates
Brindaban C. Ranu,*[a] Amit Saha,[a] and Subhash Banerjee[a]
Keywords: Ionic liquids / Dithiocarbamates / Multicomponent reactions / Catalysis / Rate acceleration
An easily accessible neutral ionic liquid, 1-methyl-3-pentyl-
imidazolium bromide, promoted a one-pot three-component
condensation of an amine, carbon disulfide, and an activated
other reaction media. These reactions do not require any ad-
ditional catalyst or solvent. The ionic liquid can be recovered
and recycled for subsequent reactions. A plausible mecha-
alkene/dichloromethane/epoxide to produce the correspond- nism is suggested.
ing dithiocarbamates in high yields at room temperature. The
reactions are very fast in ionic liquids relative to those in
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
amine and carbon disulfide by using 1-methyl-3-pentylimid-
azolium bromide {[pmIm]Br} at 0 °C to generate a dithio-
carbamate anion, which subsequently underwent Michael-
type addition to conjugated alkenes followed by condensa-
tion with methylene halides and reaction with epoxides
Introduction
Room-temperature ionic liquids have been the subject of
considerable interest since their introduction as “green” sol-
vents for reactions.[1] Besides their usefulness as powerful
reaction media, ionic liquids have been well recognized as
efficient catalysts and successfully applied in many organic
reactions.[2] They are also able to dictate the course of a
reaction.[3] We encountered a remarkable acceleration in the
rate of a reaction with the use of a simple ionic liquid,
which will be reported here.
to give
a variety of functionalized dithiocarbamates
(Scheme 1).
Dithiocarbamates have received considerable attention in
recent times because of their occurrence in a variety of bio-
logically active compounds.[4] They also play pivotal roles in
agriculture,[5] and they act as linkers in solid-phase organic
synthesis.[6] In addition, functionalized carbamates are an
important class of compounds and their medicinal and bio-
logical properties warrant study.[4] Thus, the synthesis of
dithiocarbamates with varied substitution at the thiol chain
is receiving continued interest. A variety of reagents and
catalysts including Mitsunobu’s reagent,[7a] solid LiClO4/
DMF,[7b] DMSO,[7c] and Cs2CO3/tetrabutylammonium
iodide[7d] have been used. Recently, a few catalyst- and
organic-solvent-free procedures performed either in
water[7b,7e] or neat[8a,8b] were reported. Although all of these
procedures are quite satisfactory, several of them involve
costly and toxic reagents and long reaction times. However,
an alternative procedure that is simpler and faster is always
appreciated. As a part of our continuing commitment[9] to
explore ionic liquids in organic reactions, we observed a
significant rate acceleration in the reaction between an
Scheme 1. Synthesis of dithiocarbamates.
Results and Discussion
The experimental procedure is very simple. To a cooled
(0 °C) and stirred mixture of amine, carbon disulfide, and
[pmIm]Br (20 mol-%) was added conjugated alkene/methyl-
ene halide/epoxide. The reaction mixture was stirred at
room temperature for a certain period of time (TLC) and
worked up as usual to provide the product.
Several structurally diverse amines underwent reactions
with a variety of conjugated alkenes and carbon disulfide
in the presence of the [pmIm]Br ionic liquid in one pot to
provide the corresponding dithiocarbamates. The conju-
gated alkenes included a wide range of substrates such as
[a] Department of Organic Chemistry, Indian Association for the
Cultivation of Science,
Jadavpur, Kolkata 700032, India
Fax: +91-33-24732805
E-mail: ocbcr@iacs.res.in
Eur. J. Org. Chem. 2008, 519–523
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
519

B. C. Ranu, A. Saha, S. Banerjee
FULL PAPER
Table 1. Nucleophilic addition of dithiocarbamate anions to α,β-unsaturated esters, nitriles, ketones, amides, and car-
Michael acceptors.
boxylic acids, whereas the amines involved in this reaction
were piperidine, pyrrolidine, proline, morpholine, piperazine
benzylamine, and diethylamine. The results are summarized
in Table 1. As is evident from the results, proline partici-
pated in this addition reaction, as did the other amines,
without any difficulty, and the chiral dithiocarbamate ob-
tained (Table 1, Entry 14) may be of interest as a catalyst.
Benzylamine provided the corresponding dithiocarbamates
(Table 1, Entries 17 and 18) in high yields without any side
product formation by a direct aza-Michael reaction. The
involvement of N-phenylpiperazine in this reaction (Table 1,
Entries 22–24) is addressed for the first time and the corre-
sponding dithiocarbamates may be of importance for bio-
logical activity.
To exploit this in situ generated dithiocarbamate anion
for other useful reactions, we next explored its addition to a
methylene halide to achieve a symmetrical dithiocarbamate.
Thus, several cyclic and open-chain amines were subjected
to reactions with carbon disulfide and methylene halides in
the presence of [pmIm]Br at room temperature to produce
the corresponding dithiocarbamates. Although the reaction
proceeded equally well with CH2Cl2, CH2Br2, and CH2I2,
CH2Cl2 was chosen in consideration of its widespread avail-
ability and low cost. The results are summarized in Table 2.
Table 2. Synthesis of symmetrical dithiocarbamates.
[a] The yields refer to those of pure isolated products characterized
1
by spectroscopic (IR, H NMR and 13C NMR) data.
These symmetrical dithiocarbamates bis(N,N-dialkylthio-
carbamoylthio) methane were used as valuable intermedi-
ates in the synthesis of several biologically active mole-
[a] The yields refer to those of pure isolated products characterized
1
by spectroscopic (IR, H NMR and 13C NMR) data.
520
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Catalysis by Ionic Liquids
cules.[10] The preparation of this type of dithiocarbamate Table 3. Regio- and stereoselective reaction of epoxides with dithio-
carbamate anions.
was reported earlier; the procedure involved the reaction of
dithiocarbamate anions generated from the sodium salt of
either the corresponding dithiocarbamic acid or the thiols
with dichloromethane by using
RhCl(PPh3)3
a
catalyst such as
[11]
and polyethylene glycol (PEG).[12] How-
ever, these reactions required long times of 24 and 12 h,
respectively, and the yields were also not always satisfactory.
The dithiocarbamate anions also participated in ring
cleavage of epoxides to produce the corresponding hydroxy
dithiocarbamates. The results are presented in Table 3. The
reactions of a variety of epoxides with different cyclic and
open-chain amines proceeded smoothly at room tempera-
ture. The cleavages were highly regio- and stereoselective.
In alkyl-substituted epoxides, nucleophilic attack took place
at the less-substituted carbon atom to produce the second-
ary alcohols (Markovnikov product) exclusively. The cyclo-
hexene oxides furnished the trans hydroxy derivatives as the
sole product. However, the reactions of styrene oxides were
quite different. The dithiocarbamate anions generated from
the reactions of piperidine, pyrrolidine, and morpholine
with CS2 were treated with styrene oxides to afford a mix-
ture of products. The major isomer in all of these reactions
was the secondary alcohol, which resulted from the usual
Markovnikov addition. The minor isomer was the anti-
Markovnikov product, which was formed by cleavage at the
benzylic position. Although the styrene epoxide was usually
cleaved by nucleophiles at the benzylic carbon atom exclu-
sively or selectively, in this case, because the dithiocarb-
amate anion is bulky and stable, it preferred to attack at
the less-substituted carbon atom.
All the reactions included in Tables 1–3 were very fast
(10–30 min), clean, and high yielding. Significant rate accel-
eration in an ionic liquid was observed as exemplified by
comparison of the results of a few representative reactions
in different media as shown in Table 4. The use of organic
solvents such as THF, acetonitrile, and toluene in place of
the ionic liquid did not produce very good results (much
longer reaction times and relatively low yield). The catalytic
activity of the [pmIm]Br ionic liquid was established by the
fact that without it the neat reactions took much longer
(Table 4) and provided lower yields of products. Although
the reactions can be carried out with amounts as low as
10 mol-% of the ionic liquid, it was found that 20 mol-%
[a] The yields refer to those of pure isolated products characterized
1
by spectroscopic (IR, H NMR and 13C NMR) data.
Table 4. Comparison of the results of reactions of the dithiocarb-
provided the best results in terms of reaction time and yield. amate anion in H2O, neat, and [pmIm]Br.
The ionic liquid was recycled in subsequent reactions with-
out any loss of efficiency.
Although we do not have any experimental evidence to
support a reaction path, we speculate that the imidazolium
cation of [pmIm]Br activates CS2 towards nucleophilic at-
tack by amine to generate a dithiocarbamate anion, which
can then undergo Michael-type addition to conjugated al-
kenes to afford the substituted dithiocarbamate, as outlined
in Scheme 2.
The key role of the imidazolium cation in this reaction
is also supported by the fact that other imidazolium ionic
liquids such as [pmIm]BF4 also produced comparable re-
sults.
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521

B. C. Ranu, A. Saha, S. Banerjee
FULL PAPER
NMR, 13C NMR, HRMS) and elemental analysis, and the data
are provided below.
1-(4-Chlorophenyl)-3-oxo-3-phenylpropyl Pyrrolidine-1-carbodithio-
ate (Table 1, Entry 10): Colorless viscous liquid. IR (neat): ν =
˜
1683, 1490, 1334, 1222, 1180, 1008, 954 cm–1. 1H NMR (300 MHz,
CDCl3): δ = 1.87–2.06 (m, 4 H), 3.54–3.61 (m, 2 H), 3.70 (dd, J =
9, 16 Hz, 1 H), 3.88 (t, J = 6 Hz, 2 H), 4.07 (dd, J = 6, 18 Hz, 1
H), 5.75 (dd, J = 6, 9 Hz, 1 H), 7.23 (d, J = 9 Hz, 2 H), 7.36–7.55
(m, 5 H), 7.94 (d, J = 6 Hz, 2 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 24.0, 25.9, 44.8, 49.6, 50.4, 54.7, 127.9 (2 C), 128.4 (2
C), 128.5 (2 C), 129.6 (2 C), 133.1 (2 C), 136.2, 138.3, 190.4,
196.5 ppm. C20H20ClNOS2 (389.96): calcd. C 61.60, H 5.17, N
3.59; found C 61.48, H 5.10, N 3.46.
Scheme 2. Plausible Mechanism.
1-(2-Cyanoethylsulfanylthiocarbonyl)-2-pyrrolidinoic Acid (Table 1,
Entry 14): White crystalline solid, m.p. 125–126 °C. IR (KBr): ν =
˜
2968, 2922, 2873, 2746, 2252, 1716, 1421, 1346, 1325, 1294, 1228,
1
1180, 1157, 1043, 1010, 952 cm–1. H NMR (300 MHz, CDCl3): δ
Conclusions
= 1.91–2.10 (m, 4 H), 2.60–2.65 (m, 2 H), 3.23–3.32 (m, 2 H), 3.52–
3.62 (m, 2 H), 4.81–4.84 (m, 1 H), 10.20 (br., 1 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 18.0, 24.5, 29.1, 31.7, 51.0, 66.2, 118.3,
175.9, 193.2 ppm. [α]D = –10.6522 (c = 1.38, CHCl3). C9H12N2O2S2
(244.34): calcd. C 44.24, H 4.95, N 11.47; found C 44.10, H 4.83,
N 11.38.
The present procedure that involves the use of a simple
and inexpensive ionic liquid, [pmIm]Br, provides a novel
protocol for the generation of dithiocarbamate anions and
their reaction with conjugated alkenes, methylene halides,
and epoxides to furnish a library of diversely substituted
dithiocarbamates. The dithiocarbamates are of high impor-
tance in academia as well as in industry.[4–7] It is also note-
worthy that the [pmIm]Br ionic liquid works here as a cata-
3-Oxocyclohexyl Morpholine-4-carbodithioate (Table 1, Entry 21):
Yellowish solid, m.p. 82–84 °C. IR (KBr): ν = 2960, 2923, 2866,
˜
1697, 1454, 1419, 1303, 1271, 1220, 1207, 1116, 1028, 1001, 962,
lyst as well as the reaction medium and accelerates the rate 869 cm–1. 1H NMR (300 MHz, CDCl3): δ = 1.81–1.92 (m, 2 H),
2.04–2.07 (m, 1 H), 2.31–2.41 (m, 3 H), 2.48–2.57 (m, 1 H), 2.87–
2.93 (m, 1 H), 3.73–3.76 (m, 4 H), 3.94 (br., 2 H), 4.28–4.42 (m, 3
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 24.2, 30.9, 40.9, 46.9,
49.0, 50.7 (2 C), 66.1 (2 C), 195.1, 208.1 ppm. C11H17NO2S2
(259.39): calcd. C 50.93, H 6.61, N 5.40; found C 50.77, H 6.58, N
5.21.
of the reaction. Thus, the significant advantages of this pro-
cedure include remarkably fast reactions relative to those in
other procedures, high yields, excellent regio- and stereo-
selectivity, and the reusability of the ionic liquids.
Methyl
3-(4-Phenylpiperazine-1-carbothioylsulfanyl)propionoate
Experimental Section
(Table 1, Entry 22): Pale-yellow viscous liquid. IR (neat): ν = 2993,
˜
2949, 2918, 2823, 1735, 1598, 1579, 1494, 1469, 1423, 1386, 1357,
1274, 1224, 1174, 1153, 1022, 1002, 941 cm–1. 1H NMR (300 MHz,
CDCl3): δ = 2.81 (t, J = 6 Hz, 2 H), 3.22–3.25 (m, 4 H), 3.59 (t, J
= 6 Hz, 2 H), 3.68 (s, 3 H), 4.06 (br., 2 H), 4.40 (br., 2 H), 6.86–6.90
(m, 3 H), 7.24–7.29 (m, 2 H) ppm. 13C NMR (75 MHz, CDCl3): δ
= 32.0, 34.1, 48.9 (2 C), 50.2, 51.8, 52.2, 116.6 (2 C), 120.8, 129.5
(2 C), 150.6, 172.7, 196.6 ppm. C15H20N2O2S2 (324.46): calcd. C
55.53, H 6.21, N 8.63; found C 55.35, H 6.15, N 8.43.
Representative Procedure for the Reaction of a Dithiocarbamate
Anion with a Conjugated Alkene. Preparation of 2-Cyanoethyl Pyr-
rolidine-1-carbodithioate (Table 1, Entry 7): Carbon disulfide
(304 mg, 4 mmol) was added drop by drop to a stirred mixture of
pyrrolidine (142 mg, 2 mmol) in [pmIm]Br[13] (94 mg, 0.4 mmol) at
0 °C. This mixture was stirred for 2 min and acrylonitrile (133 mg,
2.5 mmol) was added. The reaction mixture was then stirred at
room temperature (28–30 °C) for 10 min (TLC) until completion
of the reaction. The whole mixture was extracted with Et2O
(3ϫ10 mL), and the upper organic layer was washed with H2O,
dried (Na2SO4), and evaporated to leave the crude product, which
was purified by column chromatography over silica gel (hexane/
ether, 80:20) to provide the pure product as a pale-yellow solid.
Yield: 392 mg (98%), m.p. 72–74 °C. The spectroscopic data (IR,
1H NMR and 13C NMR) are in good agreement with the reported
values.[7e] The remaining ionic liquid was rinsed with ether, dried
under vacuum, and reused for four runs after which fresh ionic
liquid was added to compensate for the loss during washing with
ether.
2-Cyanoethyl 4-Phenylpiperazine-1-carbodithioate (Table 1, En-
try 23): Yellowish solid, m.p. 76–77 °C. IR (KBr): ν = 2914, 2819,
˜
2241, 1600, 1579, 1504, 1492, 1471, 1433, 1417, 1388, 1328, 1269,
1149, 1028 cm–1. 1H NMR (300 MHz, CDCl3): δ = 2.58 (t, J =
6 Hz, 2 H), 3.26 (t, J = 3 Hz, 4 H), 3.53 (t, J = 6 Hz, 2 H), 4.04
(br., 2 H), 4.42 (br., 2 H), 6.82–6.91 (m, 3 H), 7.24–7.29 (m, 2 H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 17.9, 31.5, 48.4 (2 C), 50.3,
51.7, 116.0 (2 C), 118.1, 120.4, 129.1 (2 C), 149.9, 194.1 ppm.
C14H17N3S2 (299.44): calcd. C 57.70, H 5.88, N 14.42; found C
57.43, H 5.78, N 14.22.
3-Oxo-1,3-diphenylpropyl 4-Phenylpiperazine-1-carbodithioate (Table 1,
This procedure was followed for all the reactions listed in Tables 1,
2, and 3. Although this procedure was described on the mmol scale,
gram-scale reactions also provided uniform results.
Entry 24): Yellowish viscous liquid. IR (neat): ν = 3058, 3012, 2989,
˜
2923, 2819, 1664, 1598, 1577, 1494, 1448, 1415, 1334, 1213, 1016,
1
999, 923, 756 cm–1. H NMR (300 MHz, CDCl3): δ = 3.29 (br., 4
Many of these products are known compounds and were easily
identified by comparison of their spectroscopic data and melting
points with those reported (references in Tables 1–3). Unknown
compounds were properly characterized by spectroscopy (IR, 1H
H), 3.78 (dd, J = 9, 15 Hz, 1 H), 4.09–4.16 (m, 3 H), 4.45 (br., 2
H), 5.77 (dd, J = 3, 10 Hz, 1 H), 6.89–6.91 (m, 4 H), 7.23–7.46 (m,
9 H), 7.95–7.98 (m, 2 H) ppm. 13C NMR (75 MHz, CDCl3): δ =
45.1, 48.6 (2 C), 50.3 (2 C), 51.4, 116.2 (2 C), 120.5, 127.7, 128.0
522
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Catalysis by Ionic Liquids
(2 C), 128.4 (4 C), 128.5 (2 C), 129.2 (2 C), 133.1, 136.5, 139.1,
2856, 1463, 1427, 1384, 1271, 1232, 1188, 1114, 995 cm–1. 1H NMR
150.2, 195.5, 196.8 ppm. C26H26N2OS2 (446.63): calcd. C 69.92, H (300 MHz, CDCl3): δ = 3.0 (d, J = 3 Hz, 1 H), 3.62 (dd, J = 9,
5.87, N 6.27; found C 69.67, H 5.48, N 6.21.
12 Hz, 1 H), 3.79–3.81 (m, 4 H), 3.93 (dd, J = 3, 15 Hz, 1 H), 4.03
(br., 2 H), 4.37 (br., 2 H), 5.04–5.09 (m, 1 H), 7.28–7.51 (m, 5 H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 45.2, 51.3 (2 C), 66.4 (2 C),
73.1, 125.9 (2 C), 128.0, 128.7 (2 C), 142.9, 197.9 ppm. HRMS:
calcd. for C13H17NO2S2 [M + Na]+ 306.0598; found 306.0625.
Benzylthiocarbamolylsylfanylmethyl Benzyldithiocarbamate (Table 2,
Entry 5): White solid, m.p. 106–107 °C. IR (KBr): ν = 3282, 1504,
˜
1452, 1375, 1317, 1247, 1091, 1060, 927, 729 cm–1. 1H NMR
(300 MHz, CDCl3): δ = 4.85 (d, J = 6 Hz, 4 H), 5.21 (s, 2 H), 7.26–
7.42 (m, 10 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 42.5, 51.5
(2 C), 128.1 (2 C), 128.4 (4 C), 129.0 (4 C), 135.8 (2 C), 196.3 (2 C)
ppm. C17H18N2S4 (378.60): calcd. C 53.93, H 4.79, N 7.40; found C
53.71, H 4.53, N 7.22.
Acknowledgments
(4-Phenylpiperazinethiocarbamoylsulfanyl)methyl 4-Phenylpiperaz-
inedithiocarboamate (Table 2, Entry 8): White solid, m.p. 196–
This investigation has enjoyed the financial support of the Depart-
ment of Science and Technology Project, New Delhi (SR/S5/GC-
02/2006). A. S. and S. B. thank the Council of Scientific and Indus-
trial Research, New Delhi, for their fellowships.
198 °C. IR (KBr): ν = 2918, 2839, 1600, 1471, 1440, 1421, 1384,
˜
1
1325, 1232, 1220, 1016, 993 cm–1. H NMR (300 MHz, CDCl3): δ
= 3.30–3.31 (m, 8 H), 4.07 (br., 4 H), 4.48 (br., 4 H), 5.48 (s, 2 H),
6.90–6.97 (m, 6 H), 7.27–7.32 (m, 4 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 45.7, 48.8 (4 C), 50.0 (2 C), 50.8 (2 C), 116.4 (4 C),
120.7 (2 C), 129.4 (4 C), 150.2 (2 C), 196.0 (2 C) ppm. C23H28N4S4
(488.76): calcd. C 56.52, H 5.77, N 11.46; found C 56.32, H 5.71,
N 11.23.
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Diisopropyldithiocarb-
amate (Table 2, Entry 9): White solid, m.p. 137–139 °C. IR (KBr):
ν = 2968, 2927, 2869, 2736, 1473, 1440, 1365, 1311, 1220, 1190,
˜
1139, 1112, 1028, 956 cm–1. 1H NMR (300 MHz, CDCl3): δ = 1.34
(br., 24 H), 4.12 (br., 2 H), 4.75 (br., 2 H), 5.40 (s, 2 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 19.8 (8 C), 44.0, 52.6 (2 C), 54.9 (2
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2-Hydroxyoctyl Pyrrolidine-1-carbodithioate (Table 3, Entry 1): Yel-
lowish viscous liquid. IR (neat): ν = 3408, 2925, 2856, 1461, 1434,
˜
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1330, 1249, 1220, 1184, 1161, 1006, 954 cm–1. 1H NMR (300 MHz,
CDCl3): δ = 0.81–0.86 (m, 3 H), 1.21–1.53 (m, 10 H), 1.91–2.09
(m, 4 H), 2.79 (br., 1 H), 3.31 (dd, J = 9, 15 Hz, 1 H), 3.62–3.68
(m, 3 H), 3.86–3.90 (m, 3 H) ppm. 13C NMR (75 MHz, CDCl3): δ
= 14.0, 22.6, 24.3, 25.5, 26.0, 29.2, 31.7, 36.6, 43.0, 50.8, 55.3, 71.0,
193.2 ppm. HRMS: calcd. for C13H25NOS2 [M + Na]+ 298.1275;
found 298.1250.
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dron 2005, 61, 9157–9163; d) R. N. Salvatore, S. Sahab, K. W.
Jung, Tetrahedron Lett. 2001, 42, 2055–2058; e) N. Azizi, F.
Aryanasab, L. Torkiyan, A. Ziyaei, M. R. Saidi, J. Org. Chem.
2006, 71, 3634–3635.
2-Hydroxyoctyl Piperidine-1-carbodithioate (Table 3, Entry 2):
White viscous liquid. IR (neat): ν = 3398, 2927, 2856, 1473, 1454,
˜
1427, 1280, 1228, 1132, 1114, 1004, 977 cm–1. 1H NMR (300 MHz,
CDCl3): δ = 0.79–0.81 (m, 3 H), 1.18–1.53 (m, 10 H), 1.64 (br., 6
H), 2.58 (br., 1 H), 3.30 (dd, J = 9, 15 Hz, 1 H), 3.64 (dd, J = 3,
12 Hz, 1 H), 3.85 (br., 3 H), 4.22 (br., 2 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 14.4, 23.0, 24.6, 25.9, 26.4 (2 C), 29.6, 32.1,
37.1, 44.1, 51.9, 53.8, 71.4, 196.4 ppm. HRMS: calcd. for
C14H27NOS2 [M + Na]+ 312.1432; found 312.1406.
[8] a) N. Azizi, B. Pourhasan, F. Aryanasab, M. R. Saidi, Synlett
2007, 1239–1242; b) N. Azizi, F. Aryanasab, M. R. Saidi, Org.
Lett. 2006, 8, 5275–5277.
[9] B. C. Ranu, S. Banerjee, R. Jana, Tetrahedron 2007, 63, 776–
782 and references cited therein.
2-Hydroxyoctyl Morpholine-4-carbodithioate (Table 3, Entry 3):
Yellowish viscous liquid. IR (neat): ν = 3396, 2956, 2925, 2856,
˜
1512, 1463, 1417, 1269, 1228, 1114, 1028, 995 cm–1. 1H NMR [10] S. Ekthawatchai, S. Kamchonwongpaisan, P. Kongsaeree, B.
Tarnchompoo, Y. Thebtaramonth, Y. Yuthavong, J. Med.
Chem. 2001, 44, 4688–4695.
[11] K. Tanaka, K. Ariki, Org. Lett. 2005, 7, 1537–1539.
[12] C. Cespedes, J. C. Vega, Phosphorus, Sulfur Silicon Relat. Elem.
1994, 90, 155–158.
[13] V. V. Namboodiri, R. S. Varma, Org. Lett. 2002, 4, 3161–3163.
[14] J. L. Garraway, J. Chem. Soc. 1962, 4072–4076.
Received: September 8, 2007
(300 MHz, CDCl3): δ = 0.75–0.81 (m, 3 H), 1.18–1.54 (m, 10 H),
2.65 (br., 1 H), 3.31 (dd, J = 9, 13 Hz, 1 H), 3.63–3.71 (m, 5 H),
3.80–3.88 (m, 1 H), 3.95 (br., 2 H), 4.23 (br., 2 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 14.1, 22.7, 25.5, 29.3, 31.8, 36.8, 43.7, 51.7
(2 C), 66.2 (2 C), 71.0, 198.1 ppm. HRMS: calcd. for C13H25NO2S2
[M + Na]+ 314.1224; found 314.1250.
2-Hydroxy-2-phenylethyl Morpholine-4-carbodithioate (Table 3, En-
try 9): White solid, m.p. 146–147 °C. IR (KBr): ν = 3398, 2910,
Published Online: November 12, 2007
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Eur. J. Org. Chem. 2008, 519–523
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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