Ionic liquid promoted regio- and stereo-selective thiolysis of epoxides-A simple and green approach to β-hydroxy- and β-keto sulfides

Article abstract of DOI:10.1071/CH06434

A variety of epoxides underwent facile cleavage by thiols under the catalysis of 1-methyl-3-butylimidazolium bromide, [bmIm]Br, to produce the corresponding β-hydroxy sulfides with high regio- and stereo-selectivity. On the other hand, a specially designed basic ionic liquid, [bmIm]OH, efficiently catalyzes the thiolysis of ,β-epoxy ketones providing β-keto sulfides through simultaneous retro-aldol cleavages. The reactions are clean, high yielding, and do not require any organic solvent. The catalyst is also recycled. CSIRO 2007.

Full text of DOI:10.1071/CH06434

Full Paper
CSIRO PUBLISHING
Aust. J. Chem. 2007, 60, 278–283
www.publish.csiro.au/journals/ajc
Ionic Liquid Promoted Regio- and Stereo-Selective Thiolysis
of Epoxides—A Simple and Green Approach to β-Hydroxy
and β-Keto Sulfides
Brindaban C. Ranu,A,B Tanmay Mandal,A Subhash Banerjee,A
and Suvendu S. DeyA
ADepartment of Organic Chemistry, Indian Association for the Cultivation of Science,
Jadavpur, Kolkata 700032, India.
BCorresponding author. Email: ocbcr@iacs.res.in
A variety of epoxides underwent facile cleavage by thiols under the catalysis of 1-methyl-3-butylimidazolium bromide,
[bmIm]Br, to produce the corresponding β-hydroxy sulfides with high regio- and stereo-selectivity. On the other hand, a
specially designed basic ionic liquid, [bmIm]OH, efficiently catalyzes the thiolysis of α,β-epoxy ketones providing β-keto
sulfides through simultaneous retro-aldol cleavages. The reactions are clean, high yielding, and do not require any organic
solvent. The catalyst is also recycled.
Manuscript received: 16 November 2006.
Final version: 6 February 2007.
Introduction
Results and Discussion
Epoxides are very useful intermediates in organic synthesis as
their ring opening by various nucleophiles leads to important
1,2-difunctionalized systems with trans stereochemistry.[1] The
nucleophilic ring opening of epoxides by thiols (thiolysis) is of
much importance as the products, β-hydroxy sulfides, consti-
tute a common structural component in a vast group of natural
products[2] and are also very useful intermediates in organic
synthesis.[3] A variety of reagents, both acidic and basic, have
been employed for this reaction.[4] However, many of them suf-
fer from such disadvantages as harsh reaction conditions, poor
regioselectivity, unsatisfactory yields, long reaction times, and
formation of side products.[4]
Ionicliquidshaveattractedincreasinginterestasenvironmen-
tally benign reaction media in the context of green synthesis.[5]
However, we envisioned ionic liquids as having more poten-
tial than being used as mere green solvents, and initiated an
investigation to explore the catalytic activities of ionic liquids.[6]
We report here the application of two different ionic liquids as
catalysts in the thiolysis of epoxides (Scheme 1).
The experimental procedure is very simple. A mixture of epox-
ide, thiophenol, and ionic liquid was stirred at room temperature
for a certain time as required to complete the reaction (TLC).
The product was isolated by direct distillation from the reaction
vessel. The residual ionic liquid was washed with ethyl acetate
and, after being dried under vacuum, was reused for subsequent
reactions six times without much loss of efficiency. However,
after six runs fresh ionic liquid was mixed in to compensate for
the loss of ionic liquid after each wash, for comparable results
in subsequent runs.
A wide range of structurally diverse epoxides underwent
cleavage by several thiophenols using this procedure to gener-
ate the corresponding β-hydroxy sulfides in high yields. The
results are summarized in Table 1. The cleavages are highly
regio- and stereo-selective. As expected, attack of thiolate ion
occurred exclusively at the less hindered carbon atom of the ter-
minal alkyl-substituted epoxides (entries 1–6). However, in the
aryl-substituted epoxide (entry 7), the thiolate anion struck at the
benzylic carbon atom. The cyclic epoxides (entries 8–11) pro-
duced sterospecifically trans-diequatorial β-hydroxy sulfides.
The cleavage of α,β-epoxy ketones (entries 12, 13) under the
catalysis of [bmIm]Br was unsatisfactory. A mixture of products
was isolated in one case (entry 12), while a very low yield was
obtained in the other (entry 13). Thus, we switched to a specially
designed basic ionic liquid, [bmIm]OH,[6h] for the thiolysis of
α,β-epoxy ketones.
OH
O
[bmIm]Br
R2
R2
R1
R1
R1
RSH, room temp.
SR
O
R1
[bmIm]OH
R2
A wide variety of α,β-epoxy ketones were found to undergo
facile reactions with thiols followed by subsequent retro-aldol
cleavages in the presence of this ionic liquid to produce the
corresponding α-thioalkyl ketones. The results are presented in
Table 2. The reaction is uniform in the case of acyclic α,β-epoxy
ketones irrespective of their substitutions, aliphatic or aromatic.
SR
RSH, room temp.
O
O
R, R1, R2 = alkyl/aryl
Scheme 1.
© CSIRO 2007
10.1071/CH06434
0004-9425/07/040278

Simple and Green Approach to β-Hydroxy and β-Keto Sulfides
279
Table 1. [bmIm]Br catalyzed thiolysis of epoxides
Entry
1
Epoxide
Thiol
PhSH
Time [h]
2.0
Product(s)A
Yield [%]B
95
Ref.
OH
O
O
O
[4g]
SPh
5
5
5
5
OH
S(4-ClC6H4)
SCH2Ph
2
3
4-ClC6H4SH
PhCH2SH
2.0
4.5
90
80
5
OH
[4b]
5
OH
[4d]
[4d]
O
4
5
PhSH
2.0
4.5
90
80
Cl
Cl
Cl
SPh
OH
O
O
PhCH2SH
Cl
SCH2Ph
OH
[4d]
[4d]
6
7
PhSH
PhSH
2.5
3.5
85
85
PhO
Ph
PhO
SPh
OH
O
O
SPh
Ph
Ph
(66%)
ϩ
SPh
OH
(34%)
PhS
[4d]
[4d]
8
9
PhSH
PhSH
3.5
3.0
80
95
OH
Ph
Ph
SPh
O
OH
S(4-ClC6H4)
10
11
4-ClC6H4SH
PhSH
4.0
4.5
85
80
O
O
OH
SPh
[4i]
[4i]
OH
2
3
2
SPh
O
12
PhSH
5.0
80
OH
OH
3
O
O
Me
Ph
Me
Ph
O
SPh
13
14
PhSH
PhSH
3.5
5.0
80
30
ϩ
O
SPh
Me
O
O
[9]
Ph
Ph
SPh
O
Ph
AIn entry 13, the ratio of products (66:11 syn/anti) was determined by 1H NMR spectroscopic analysis.
BYields refer to those pure isolated products characterized by spectroscopic data (IR, 1H NMR, and 13C NMR spectroscopy).

280
B. C. Ranu et al.
Table 2. Thiolysis of α,β-epoxy ketones using [bmIm]OH
Entry
1
Epoxide
Thiol
PhSH
Time [min]
15
Product(s)
Yield [%]A
Ref.
O
O
[10]
80
75
90
90
90
80
90
90
80
85
76
90
88
90
Me
SPh
O
Me
Me
Me
Ph
Ph
Ph
Ph
O
O
O
O
O
O
O
O
O
O
O
O
O
2
BunSH
PhSH
20
10
10
12
20
10
12
12
10
20
10
12
20
Me
Ph
Ph
Ph
Ph
Ph
Ph
Ph
SBun
SPh
O
O
O
O
O
O
O
[10]
[11]
[11]
3
Me
Ph
Ph
Ph
Ph
4
EtSH
SEt
5
BunSH
ButSH
PhSH
SBun
SBut
SPh
6
[9]
[11]
[11]
[9]
7
O
8
PhCH2SH
BunSH
PhSH
Ph
O
SCH2Ph
SBun
SPh
Ph
O
O
O
O
9
Ph
Ph
(4-ClC6H4)
(4-ClC6H4)
O
Ph
Ph
Ph
Ph
O
10
11
12
13
14
O
O
ButSH
PhSH
(4-OMeC6H4)
(4-OMeC6H4)
Ph
SBut
SPh
O
O
[9]
Ph
O
O
O
[12]
PhSH
Ph
O
SPh
4-MeC6H4
4-MeC6H4
O
O
[12]
PhSH
Ph
SPh
4-MeOC6H4
4-MeOC6H4
O
(Continued)

Simple and Green Approach to β-Hydroxy and β-Keto Sulfides
281
Ref.
Table 2. (Continued)
Entry
15
Epoxide
Thiol
Time [min]
Product(s)
Yield [%]A
90
O
O
O
ButSH
25
20
SBut
SPh
Ph
Ph
4-BrC6H4
4-BrC6H4
O
O
O
16
17
PhSH
PhSH
85
90
4-BrC6H4
4-BrC6H4
O
O
O
SPh
[4h]
45
65
O
O
O
SBun
18
BunSH
70
O
O
SPh
[4h]
19
20
PhSH
PhSH
50
55
85
82
O
SPh
O
O
O
A Yields refer to those pure isolated products characterized by spectroscopic data (IR, 1H, and 13C NMR spectroscopy).
However, reactions of cyclic α,β-epoxy ketones proceeded by
a different course. They underwent thiolysis followed by dehy-
dration to provide the corresponding α-thioalkyl α,β-unsaturated
ketones(entries17–20). α-Alkylationofα,β-unsaturatedketones
is an important process and is difficult to achieve by other
protocols.[7]
efficiency providing recyclability of the catalyst; and green
aspects using no hazardous organic solvents in the process.
Moreover, these experiments demonstrate the potential of ionic
liquids as efficient catalysts, and show much promise for further
useful applications.
In general, the reactions are very clean and fast. No side reac-
tionwasobservedwithanysubstrate.Theionicliquids[bmIm]Br
and [bmIm]OH are apparently non-toxic. The reactions were not
initiated without ionic liquid as revealed by blank experiments.
The crude products obtained were sufficiently pure, and purifi-
cation by short column chromatography gave analytically pure
samples. The stereochemistry of the products was easily deter-
Experimental
General
The ionic liquids [bmIm]Br and [bmIm]OH were prepared fol-
lowing reported procedures.[6h,8] IR spectra were taken as thin
films for liquid compounds and as KBr pellets for solids. 1H and
13C NMR spectra were recorded in CDCl3 solutions at 300 and
75 MHz, respectively.
1
mined by H NMR and 13C NMR spectroscopic analysis. The
ionic liquids play vital roles both as catalysts and reaction media.
The possible mechanisms are outlined in Scheme 2. It is spec-
ulated that the oxygen atom of the oxirane forms a hydrogen
bond with H2 of the imidazolium moiety and thus facilitates the
nucleophilic attack of RS− onto it.
Representative Procedure for the Thiolysis of Epoxides
(Entry 1, Table 1)
Thiophenol (550 mg, 5 mmol) was added to a stirred solu-
tion of 1,2-epoxyoctane (640 mg, 5 mmol) and 1-methyl-
3-butylimidazolium bromide, [bmIm]Br (263 mg, 1.2 mmol),
at room temperature, and the mixture was stirred for 2.0 h as
required to complete the reaction (TLC). The product was then
isolated by direct distillation from the reaction vessel under
vacuum (for smaller scale reactions the product could be iso-
lated by extraction with ethyl acetate followed by purification
with silica gel column chromatography) to furnish the pure
1-phenylsulfanyloctan-2-ol (1.13 g, 95%) as a colourless liq-
uid. νmax (neat)/cm−1 1438, 1481, 3408. δH (CDCl3) 0.86–0.90
(m, 3H), 1.28–1.36 (m, 8H), 1.45–1.57 (m, 2H), 2.43 (br s, 1H),
Conclusions
This one-pot procedure using ionic liquid provides a very sim-
ple and efficient methodology for the synthesis of β-hydroxy
sulfides[13] and α-thioalkyl carbonyl compounds which are of
muchimportanceinorganicsynthesisandpharmaceuticalindus-
tries. The significant advantages offered by this method are:
fast reaction (10 min to 5 h); simple operation and mild condi-
tions (room temperature); high isolated yields (75–90%); cost

282
B. C. Ranu et al.
N
ϩ
N
Bun
OH
O
R2
H
[bmIm]Br
R2
R1
R1
O
R2
SR
R1
RSH
OHϪ
Bun
SR
ϩ
N
N
R1
R2
O
R1
R2
H
O
[bmIm]OH
O
OϪ
O
R1
R2
H–OH
O
R1
[RSϪ
]
SR
O
Scheme 2.
2.85 (dd, J 8.6, 13.6, 1H), 3.15 (dd, J 3.5, 13.6, 1H), 3.63–3.71
(m, 1H), 7.18–7.41 (m, 5H). δC (CDCl3) 14.4, 22.9, 26.0, 29.6,
32.1, 36.5, 42.5, 69.7, 126.9, 129.4 (2C), 130.3 (2C), 135.8.
These values are in good agreement with the reported data.[4g]
The residual ionic liquid was dried under vacuum and reused
for subsequent reactions. This procedure was followed for the
reactions of all epoxides listed inTables 1 and 2. However, for the
substrates inTable 2, [bmIm]OH was used in place of [bmIm]Br.
The known compounds were identified by comparison of their
spectroscopic data with those reported (see references in Tables
1 and 2), and the new compounds were fully characterized by
IR, 1H NMR, and 13C NMR spectroscopic data, and elemental
analysis. These data are provided below:
1477, 3405. δH 1.17–1.38 (m, 4H), 1.67–1.79 (m, 2H), 2.03–
2.12 (m, 2H), 2.70–2.77 (m, 1H), 2.80 (br s, 1H), 3.30 (ddd, J
4.2, 9.8, 10.0, 1H), 7.23–7.39 (m, 5H). δC 24.6, 26.4, 32.9, 34.3,
56.9, 72.7, 129.4 (2C), 131.7, 134.3, 135.3 (2C).
4-Hydroxy-4-phenyl-3-phenylsulfanylbutan-2-one
(Entry 13, Table 1)
Obtained as a colourless liquid (obtained as a mixture of
diastereoisomers in the ratio of 84:16). Found: C 70.3, H 5.8.
C16H16O2S requires C 70.6, H 5.9%. νmax (neat)/cm−1 1439,
1475, 1687, 3468. δH (for major syn isomer) 2.08 (s, 3H), 3.78
(d, J 6.6, 1H), 5.04 (d, J 6.6, 1H), 7.19–7.35 (m, 10H). δC
29.3, 66.2, 71.7, 126.9 (2C), 128.4, 129.0 (2C), 129.3, 129.5,
130.9 (2C), 133.3 (2C), 144.4, 204.3. δH (for minor anti isomer)
2.22 (s, 3H), 3.64 (d, J 8.6, 1H), 4.95 (d, J 8.6, 1H), 7.19–7.35
(m, 10H). δC 27.7, 63.7, 74.2, 127.8, 128.2 (2C), 128.5 (2C),
128.6 (2C), 129.2 (2C), 129.4, 129.6, 140.1, 205.1.
1-(4-Chlorophenylsulfanyl)octan-2-ol (Entry 2, Table 1)
Obtained as a colourless liquid. Found: C 61.5, H 7.5.
C14H21ClOS requires C 61.6, H 7.8%. νmax (neat)/cm−1 1439,
1479, 1580, 3467. δH 0.87 (t, J 6.4, 3H), 1.26–1.41 (m, 7H),
1.42–1.53 (m, 3H), 2.36 (br s, 1H), 2.84 (dd, J 8.5, 13.6, 1H),
3.08 (dd, J 3.4, 13.6, 1H), 3.62–3.70 (m, 1H), 7.23–7.32 (m,
4H). δC 14.4, 22.9, 25.9, 29.6, 32.1, 36.5, 42.7, 69.9, 129.5 (2C),
131.6 (2C), 132.9, 134.5.
1-Butylsulfanylpropan-2-one (Entry 2, Table 2)
Obtained as a pale yellow liquid. Found: C 57.3, H 9.5. C7H14OS
requires C 57.5, H 9.7%. νmax (neat)/cm−1 1355, 1465, 1705.
δH 0.86 (t, J 7.2, 3H), 1.30–1.40 (m, 2H), 1.45–1.55 (m, 2H),
2.25 (s, 3H), 2.44 (t, J 7.2, 2H), 3.16 (s, 2H). δC 13.4, 21.6, 27.4.
30.8, 31.6, 41.8, 203.0.
2-Phenyl-2-phenylsulfanylpropanol (Entry 8, Table 1)
Obtained as a colourless liquid. Found: C 73.6, H 6.4. C15H16OS
requires C 73.7, H 6.6%. νmax (neat)/cm−1 1432, 1479, 3420.
δH 1.69 (s, 3H), 4.51 (d, J 4.5, 2H), 7.32–7.96 (m, 10H). δC 26.9,
72.9, 74.1, 125.4 (2C), 127.9, 128.1, 128.8 (2C), 130.1 (2C),
133.6 (2C), 134.9, 144.5.
2-tert-Butylsulfanyl-1-phenylethanone (Entries 6 and 11,
Table 2)
Obtained as a colourless liquid. Found: C 69.0, H 7.6. C12H16OS
requires C 69.2, H 7.7%. νmax (neat)/cm−1 1276, 1448, 1596,
1682. δH 1.37 (s, 9H), 3.90 (s, 2H), 7.45–7.58 (m, 3H), 7.96–
7.99 (m, 2H). δC 30.6 (3C), 35.5, 43.5, 128.4 (2C), 128.6 (2C),
133.1, 135.5, 196.2.
2-(4-Chlorophenylsulfanyl)cyclohexanol (Entry 10, Table 1)
Obtained as a colourless liquid. Found: C 59.2, H 6.0.
C12H15ClOS requires C 59.4, H 6.2%. νmax (neat)/cm−1 1446,

Simple and Green Approach to β-Hydroxy and β-Keto Sulfides
283
1-(4-Bromophenyl)-2-tert-butylsulfanylethanone
(Entry 15, Table 2)
[4] (a) A. E. Vougioukas, H. B. Kagan, Tetrahedron Lett. 1987, 28, 6065.
doi:10.1016/S0040-4039(00)96865-5
(b) H. Yamashita, Bull. Chem. Soc. Jpn. 1988, 61, 1213.
doi:10.1246/BCSJ.61.1213
(c) J. Iqbal, A. Pandey, A. Shukla, R. Srivastava, S. Tripathi,
Tetrahedron 1990, 46, 6423. doi:10.1016/S0040-4020(01)96012-0
(d) M. Chini, P. Crotti, E. Giovani, F. Macchia, M. Pineschi, Synlett
1992, 303. doi:10.1055/S-1992-21348
Obtained as a pale yellow solid. mp 78–80◦C. Found: C 50.1,
H 5.1. C12H15BrOS requires C 50.2, H 5.3%. νmax (KBr)/cm−1
1278, 1458, 1481, 1585, 1682. δH 1.29 (s, 9H), 3.78 (s, 2H),
7.55 (d, 2H, J 8.4), 7.77 (d, 2H, J 8.4). δC 30.7 (3C), 35.6, 43.9,
128.4, 130.3 (2C), 131.9 (2C), 134.2, 195.4.
(e) J. Cossy, V. Bellosta, C. Hamoir, J.-R. Desmurs, Tetrahedron Lett.
2002, 43, 7083. doi:10.1016/S0040-4039(02)01533-2
(f) J. S. Yadav, B. V. S. Reddy, G. Baishya, Chem. Lett. (Jpn.) 2002,
31, 906. doi:10.1246/CL.2002.906
(g) F. Fringuelli, F. Pizzo, S. Tortoioli, L. Vaccaro, Tetrahedron Lett.
2003, 44, 6785. doi:10.1016/S0040-4039(03)01704-0
(h) F. Fringuelli, F. Pizzo, L. Vaccaro, J. Org. Chem. 2004, 69, 2315.
doi:10.1021/JO035804M
1-(4-Bromophenyl)-2-phenylsulfanylethanone
(Entry 16, Table 2)
Obtained as a pale yellow solid. mp 79–81◦C. Found: C 54.6, H
3.5. C14H11BrOS requires C 54.7, H 3.6%. νmax (KBr)/cm−1
1278, 1439, 1481, 1585, 1681. δH 4.14 (s, 2H), 7.16–7.24
(m, 3H), 7.29–7.32 (m, 2H), 7.53 (d, J 7.5, 2H), 7.72 (d, J 7.5,
2H). δC 40.9, 127.2, 128.4 (2C), 130.1 (2C), 130.6 (2C), 131.8
(2C), 131.8, 133.9, 145.3, 192.9.
(i) A. R. Khosropour, M. M. Khodaei, K. Ghozati, Chem. Lett. (Jpn.)
2004, 33, 1378. doi:10.1246/CL.2004.1378
[5] (a) T. Welton, Chem. Rev. 1999, 99, 2071. doi:10.1021/CR980032T
(b) P. Wasserscheid, M. Keim, Angew. Chem. Int. Ed. Engl. 2000, 39,
3773.
2-Butylsulfanylcyclohex-2-enone (Entry 18, Table 2)
(c) R. Sheldon, Chem. Commun. 2001, 2399. doi:10.1039/B107270F
(d) J. S. Wilkes, Green Chem. 2002, 4, 73. doi:10.1039/B110838G
[6] (a) B. C. Ranu, A. Das, S. Samanta, J. Chem. Soc., Perkin Trans. 1
2002, 1520. doi:10.1039/B204363G
Obtained as a colourless liquid. Found: C 64.9, H 8.6. C10H16OS
requires C 65.2, H 8.8%. νmax (neat)/cm− 1234, 1438, 1477,
1591, 1679. δH 0.92 (t, J 7.2, 3H), 1.37–1.49 (m, 2H), 1.55–1.64
(m, 2H), 1.98–2.06 (m, 2H), 2.43–2.48 (m, 2H), 2.53 (m, 2H),
2.65 (t, J 7.2, 2H), 6.70 (t, J 4.5, 1H). δC 13.6, 22.0, 22.7, 27.1,
30.4 (2C), 38.6, 136.3, 142.3, 196.0.
(b) B. C. Ranu, S. S. Dey, Tetrahedron Lett. 2003, 44, 2865.
doi:10.1016/S0040-4039(03)00439-8
(c) B. C. Ranu, S. S. Dey, A. Hajra, Tetrahedron 2003, 59, 2417.
doi:10.1016/S0040-4020(03)00289-8
(d) B. C. Ranu, S. S. Dey, Tetrahedron 2004, 60, 4183.
doi:10.1016/J.TET.2004.03.052
(e) B. C. Ranu, A. Das, Aust. J. Chem. 2004, 57, 605.
doi:10.1071/CH03318
(f) B. C. Ranu, R. Jana, S. S. Dey, Chem. Lett. (Jpn.) 2004, 33, 274.
doi:10.1246/CL.2004.274
(g) B. C. Ranu, R. Jana, Eur. J. Org. Chem. 2005, 755.
doi:10.1002/EJOC.200400597
1-Phenylsulfanyl-4,4a,5,6,7,8-hexahydro-3H-naphthalen-
2-one (Entry 20, Table 2)
Obtained as a light brown liquid. Found: C 74.3, H 6.9.
C16H18OS requires C 74.4, H 7.0%. νmax (neat)/cm−1 1439,
1477, 1582, 1674. δH 0.97–1.51 (m, 4H), 1.52–2.13 (m, 5H),
2.44–2.83 (m, 3H), 3.59–3.69 (m, 1H), 7.07–7.44 (m, 5H). δC
25.3, 27.2, 28.2, 34.6, 35.2, 37.0, 41.0, 125.3, 127.2 (2C), 128.9
(2C), 137.2, 137.4, 174.0, 195.1.
(h) B. C. Ranu, S. Banerjee, Org. Lett. 2005, 7, 3049.
doi:10.1021/OL051004H
(i) B. C. Ranu, R. Jana, J. Org. Chem. 2005, 70, 8621.
doi:10.1021/JO051373R
(j) B. C. Ranu, R. Jana, Adv. Synth. Catal. 2005, 347, 1811.
doi:10.1002/ADSC.200505122
(k) B. C. Ranu, S. Banerjee, A. Das, Tetrahedron Lett. 2006, 47, 881.
doi:10.1016/J.TETLET.2005.12.003
Accessory Publication
Spectroscopic (IR, 1H, and 13C NMR) data for all known prod-
ucts listed inTables 1 and 2 are available from the author or, until
April 2012, from the Australian Journal of Chemistry.
(l) B. C. Ranu, R. Jana, Eur. J. Org. Chem. 2006, 3767.
doi:10.1002/EJOC.200600335
(m) B. C. Ranu, K. Chattopadhyay, R. Jana, Tetrahedron 2007, 63,
155. doi:10.1016/J.TET.2006.10.035
Acknowledgments
This work has enjoyed financial support from CSIR, New Delhi [grant no.
01(1936)/04]. T.M., S.B., and S.S.D. are also thankful to CSIR for their
fellowships.
[7] (a) T. Yechezkel, E. Ghera, D. Ostercamp, A. Hassner, J. Org. Chem.
1995, 60, 5135, and references therein. doi:10.1021/JO00121A035
(b) H. J. Monteiro, A. L. Gemal, Synthesis (Mass.) 1975, 437, and
references therein. doi:10.1055/S-1975-23790
[8] V. Namboodiri, R. S. Varma, Org. Lett. 2002, 4, 3161. doi:10.1021/
OL026608P
References
[1] (a) J. B. Buchanan, H. Z. Stable, in Selective OrganicTransformations,
Vol. 2 (Ed. B. S. Thyagarajan) 1972 (Wiley–Interscience: New York,
NY).
[9] R. Seshadri, W. J. Pegg, M. Israel, J. Org. Chem. 1981, 46, 2596.
doi:10.1021/JO00325A038
(b) J. C. Mullis, W. P. Weber, J. Org. Chem. 1982, 47, 2873, and
references therein. doi:10.1021/JO00136A011
[10] B. C. Ranu, T. Mandal, J. Org. Chem. 2004, 69, 5793. doi:10.1021/
JO0493727
[2] (a) E. J. Corey, D. A. Clark, G. Goto, A. Marfat, C. Mioskowski,
C. Samuelsson, S. Hammarstrom, J. Am. Chem. Soc. 1980, 102, 1436.
doi:10.1021/JA00524A045
(b) E. J. Corey, D.A. Clark, G. Goto,Tetrahedron Lett. 1980, 21, 3143.
doi:10.1016/S0040-4039(00)77430-2
[3] R. J. Cremlyn, An Introduction to Organo-Sulfur Chemistry 1996
(Wiley & Sons: New York, NY).
[11] L. M. Long, J. Am. Chem. Soc. 1946, 68, 2159. doi:10.1021/
JA01215A011
[12] J. B. Banfield, W. Davies, N. W. Gamble, S. Middleton, J. Chem. Soc.
1956, 4791. doi:10.1039/JR9560004791
[13] After completion of our work a similar work appeared in Green Chem-
istry recently: J. Chen, H. Wu, C. Jin, X. Zhang, Y. Xie, W. Su, Green
Chem. 2006, 8, 330. doi:10.1039/B600620E