One-pot reductive sulfenylation and thiocyanation of carbonyl compounds in ionic liquid media

Article abstract of DOI:10.1080/00397910903531854

The first example of an efficient one-pot reductive sulfenylation and thiocyanation of carbonyl compounds in environmentally benign ionic liquid (IL) media is reported. The process involves reduction of carbonyl compounds with NaBH4 in the IL [bmim]BF4 followed by I2-catalyzed reaction of the resulting alcohols with aromatic/aliphatic thiols or ammonium thiocyanate in the same vessel to afford sulfides or thiocyanates, respectively, in excellent yields (78-93%). Notably, the protocol precludes the necessity to prepare and isolate the intermediate alcohols in a separate step as they are formed in situ, and the IL used can be recycled easily for further use without any loss of efficiency. Copyright

Full text of DOI:10.1080/00397910903531854

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One-Pot Reductive Sulfenylation and
Thiocyanation of Carbonyl Compounds in
Ionic Liquid Media
Lal Dhar S. Yadav a , Garima a & Ritu Kapoor a
a Green Synthesis Laboratory, Department of Chemistry, University
of Allahabad, Allahabad, India
Published online: 14 Dec 2010.
To cite this article: Lal Dhar S. Yadav , Garima & Ritu Kapoor (2010) One-Pot Reductive Sulfenylation
and Thiocyanation of Carbonyl Compounds in Ionic Liquid Media, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 41:1, 100-112, DOI:
10.1080/00397910903531854
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Synthetic Communications1, 41: 100–112, 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910903531854
ONE-POT REDUCTIVE SULFENYLATION AND
THIOCYANATION OF CARBONYL COMPOUNDS
IN IONIC LIQUID MEDIA
Lal Dhar S. Yadav, Garima, and Ritu Kapoor
Green Synthesis Laboratory, Department of Chemistry, University of
Allahabad, Allahabad, India
The first example of an efficient one-pot reductive sulfenylation and thiocyanation of
carbonyl compounds in environmentally benign ionic liquid (IL) media is reported. The
process involves reduction of carbonyl compounds with NaBH4 in the IL [bmim]BF4
followed by I2-catalyzed reaction of the resulting alcohols with aromatic / aliphatic thiols
or ammonium thiocyanate in the same vessel to afford sulfides or thiocyanates, respectively,
in excellent yields (78–93%). Notably, the protocol precludes the necessity to prepare and
isolate the intermediate alcohols in a separate step as they are formed in situ, and the IL
used can be recycled easily for further use without any loss of efficiency.
Keywords: Carbonyl compounds; ionic liquids; reduction; sulfides; thiocyanates
One of the important themes in contemporary organic synthesis is the development
of convenient and efficient methodologies for performing basic reactions. The for-
mation of the carbon–sulfur bond constitutes a key reaction in biosynthetic
processes as well as in organic synthesis.[1] Organic sulfides and thiocyanates are
of considerable importance from both chemical and biological viewpoints. They
are particularly attractive synthetic intermediates for a variety of organic tansforma-
tions[2–6] as well as important auxillary functions in many synthetic sequences.[7]
Organic sulfides are known industrially to constitute a large class of products
used in many fields, for example, as dyestuffs, natural products, pharmaceutical
intermediates, pesticides, herbicides, oxidation inhibitors, and additives for lead-
bearing lubricants.[8] The thioether fragment is an important molecular tool as bioi-
sosteric replacements in rational drug design.[9] Organic thiocyanates, representing a
masked mercapto group, are useful scaffolds for various organic transformations,
especially in the synthesis of heterocycles such as thiazoles and thiazines.[2,3,10]
The thiocyanate group is a prominent functional motif found in certain anticancer
natural products formed by the deglycosylation of glucosinolates derived from
cruciferous vegetables.[11]
Received September 6, 2009.
Address correspondence to Lal Dhar S. Yadav, Green Synthesis Laboratory, Department of
Chemistry, University of Allahabad, Allahabad 211002, India. E-mail: ldsyadav@hotmail.com
100

SULFENYLATION AND THIOCYANATION OF CARBONYLS
101
Scheme 1. One-pot sequential synthesis of benzyl=allyl sulfides=thiocyanates 3.
One of the prime concerns of industry and academia is the search for environ-
mentally benign solvent replacements for conventional organic solvents. In this area,
ionic liquids (ILs) have gained considerable interest as environmentally benign reac-
tion media, catalysts, and reagents that are easy to recycle.[12] Their high polarity and
ability to solubilize both organic and inorganic compounds can result in enhanced
rates of chemical processes and can provide higher selectivities compared to conven-
tional solvents.[13]
Several reagents and catalysts are reported in the literature for reductive ami-
nation of carbonyl compounds following direct as well as indirect approches.[14–18]
However, there has been no report on reductive sulfenylation and thiocyanation
of carbonyl compounds, which is an attractive target of investigation. One-pot
sequential multistep reactions approach can be applied for this purpose. Considering
these points and our ongoing efforts to develop new one-pot synthetic processes,[19]
we report herein the first example of an efficient one-pot direct reductive sulfenyla-
tion and thiocyanation of carbonyl compounds in IL media (Scheme 1).
RESULTS AND DISCUSSION
Initially, we examined the one-pot reductive sulfenylation of acetophenone in
different ILs: 1-butyl-3-methylimidazolium (bmim) bromide ([bmim]Br), [bmim]BF4,
[bmim]PF6, butylpyridinium (bpy) bromide ([bpy]Br), [bpy]BF4, and [bpy]PF6
(Table 1). Among these ILs, [bmim]BF4 commendably dissolved NaBH4 as well as
the other reactants and catalyst at room temperature and gave the best yield of 3a
under the reaction conditions (Table 1, entry 1). The other ILs did not completely
solubilize the reactants and catalyst at rt to give a homogenous reaction mixture.
Table 1. Optimization of ILa
Entry
IL
Timeb(h)
Yieldc (%)
1
2
3
4
5
6
[bmim]Br
[bmim]BF4
[bmim]PF6
[bpy]Br
8
4
76
91
80
66
79
73
7
10
6
[bpy]BF4
[bpy]PF6
9
aFor the experimental procedure, see the Experimental section.
bTime for the completion of the reaction as indicated by TLC.
cYield of isolated and purified product 3a.

102
L. D. S. YADAV, GARIMA, AND R. KAPOOR
Table 2. Iodine-catalyzed synthesis of benzyl=allyl sulfides and thiocyanates 3 in IL media
Entry Aldehyde=ketone 1
Nucleophile
Product 3
Reaction time (h)a Yield (%)b,c
1
4
91
89
87
2
3
4
NH4SCN
4.5
4
5
6
7
8
4
93
92
90
88
4.5
4.5
5
NH4SCN
4
86
(Continued )

SULFENYLATION AND THIOCYANATION OF CARBONYLS
103
Table 2. Continued
Entry Aldehyde=ketone 1
Nucleophile
NH4SCN
Product 3
Reaction time (h)a Yield (%)b,c
9
4.5
85
10
11
12
4.5
4.5
3
83
82
87
13
14
3
88
86
NH4SCN
3.5
15
16
17
3
3
3
89
86
NH4SCN
87
(Continued )

104
L. D. S. YADAV, GARIMA, AND R. KAPOOR
Table 2. Continued
Entry Aldehyde=ketone 1
Nucleophile
Product 3
Reaction time (h)a Yield (%)b,c
18
19
20
3.5
3.5
5
83
82
78
NH4SCN
21
22
4
81
83
4.5
aTotal time for the completion of steps (i) and (ii) as indicated by TLC.
bYield of isolated and purified product.
cAll compounds gave C, H, and N (if present) analyses within ꢁ0.37% and satisfactory spectral (IR, 1H
NMR,13C NMR, and EIMS) data.
Probably because of this, they afforded 3a in lesser yields and required longer reac-
tion times (Table 1). The requisite ILs were prepared employing known meth-
ods.[20,21] As regards the choice of catalyst, we tested several Lewis acids, ZnCl2,
FeCl3, CeCl3 ꢀ 7H2O, and I2, for the synthesis of the representative compound 3a
in [bmim]BF4. The best result was obtained with molecular iodine, which is in con-
formity with the earlier observations that I2 is a versatile catalyst for various organic
transformations,[22] including nucleophilic substitution reactions of benzylic, allylic,
and propargylic alcohols.[23,24] The optimum catalyst loading for I2 was 10 mol.%
The present optimized synthesis of 3 involves stirring of carbonyl compounds 1
with NaBH4 in [bmim]BF4 at room temperature for 0.5–3 h followed by addition of
10 mol.% of molecular iodine and PhSH=n-BuSH or NH4SCN and stirring at rt for a
further 1–2 h to afford 3 in 78–93% yields (Table 2).
It is worth mentioning here that the molecular iodine decreases the nucleophi-
licity of the hydroxyl group and facilitates either the formation of more stable car-
bocation or transition state depending upon the nature and electronic structure of

SULFENYLATION AND THIOCYANATION OF CARBONYLS
105
Scheme 2. Plausible mechanism for the formation of 3.
the carbonyl compounds and that there was no appreciable dimerization of thiols
and thiocyanates (SCN) under the present reaction conditions. This favors the
nucleophilic substitution reaction to afford the products 3. A plausible mechanism
is shown in Scheme 2. The aforementioned one-pot sulfenylation and thiocyanation
reactions proceeded expeditiously, delivered products 3 in consistently excellent
yields, and accommodated a wide range of aromatic as well as allyl aldehydes and
ketones bearing both electron-withdrawing and electron-releasing substituents
(Table 2). It was noted that substrates with electron-releasing groups gave relatively
greater yields. However, the present procedure does not work well with cyclohexa-
none and aliphatic saturated aldehydes and ketones, such as butyraldehyde and
butanone, to afford an appreciable yield of the corresponding sulfenylated=
thiocyanated products. After isolation of products 3, the IL [bmim]BF4 could be
recycled six times with up to 90% recovery and reused without any loss of efficiency.
In summary, we have developed the first expeditious one-pot synthesis of
benzyl=allyl sulfides and thiocyanates by NaBH4 reduction of aliphatic and aromatic
aldehydes and ketones followed by the reaction of PhSH=n-BuSH or NH4SCN uti-
lizing the environmentally benign solvent [bmim]BF4 and catalyst I2. The reactions
are operationally simple and tolerant to air and moisture, and the IL can be recycled
easily for further use without any loss of efficiency.
EXPERIMENTAL
Melting points were determined by open glass capillary method and are uncor-
rected. Infrared (IR), spectra in KBr were recorded on a Perkin-Elmer 993 IR spectro-
1
photometer. H NMR spectra were recorded on a Bruker WM-40 C (400-MHz)
Fourier transform (FT) spectrometer in CDCl3 using tetramethylsilene (TMS) as inter-
nal reference. 13C NMR spectra were recorded on the same instrument at 100 MHz in
CDCl3, and TMS was used as internal reference. Mass spectra (electron-impact mass
spectrometry) were recorded on a JEOL D-300 mass spectrometer. Elemental analyses
were carried out in a Coleman automatic carbon, hydrogen, and nitrogen analyzer. All
chemicals used were reagent grade and were used as received without further purifi-
cation. Silica gel G was used for thin-layer chromatography (TLC).
General Procedure for the Synthesis of Benzyl/Allyl Sulfides and
Thiocyanates 3 (Entries 1–22)
Carbonyl compound 1 (2 mmol) and NaBH4 (2 mmol) were taken in
[bmim]BF4 (5 mL), and the reaction mixture was stirred at room temperature for

106
L. D. S. YADAV, GARIMA, AND R. KAPOOR
0.5–3 h (monitored by TLC for the complete reduction of 1) followed by addition of
molecular iodine (0.2 mmol) and stirring at rt for 0.5 h. Then, PhSH=n-BuSH
(2 mmol) or NH4SCN (2 mmol) was added, and the reaction mixture was stirred
at rt for 1–2 h (Table 2). After completion of the reaction as indicated by TLC, water
(10 mL) was added and the aqueous layer was separated from the residue. The resi-
due was subjected to silica-gel column chromatography using EtOAc–hexane (1:3) as
eluent to obtain a sample of analytically pure 3. On the other hand, dichloromethane
(15 mL) was added to the aqueous layer containing the IL and stirred for 10 min. The
dichloromethane layer was separated and evaporated to afford the recycled
[(bmim)BF4], which was used in susequent runs without further purification.
Data
Phenyl(1-phenylethyl)sulfane 3 (Table 2, entry 1). Yield: 0.39 g (2 mmol,
91%); colorless liquid; IR (neat, cmꢂ1): 3060, 2910, 1598, 1575, 1490, 1445, 755,
1
690; H NMR (400 MHz, CDCl3=TMS): d 1.68 (d, J ¼ 6.8 Hz, 3 H, Me), 4.03 (q,
J ¼ 6.8 Hz, 1 H, SCH), 7.08–7.50 (m,10 Harom); 13C NMR (100 MHz, CDCl3=
TMS): d 24.0, 42.0, 122.1, 124.2, 125.4, 126.4, 127.8, 128.9, 134.5, 139.1; MS (EI):
m=z ¼ 214 [Mþ]. Anal. calcd. for C14H14S: C, 78.46; H, 6.58. Found: C, 78.24; H,
6.34.
Butyl(1-phenylethyl)sulfane (Table 2, entry 2). Yield: 0.35 g (2 mmol,
89%); colorless liquid; IR (neat, cmꢂ1): 3050, 2901, 1605, 1580, 1480, 1440, 742,
1
699; H NMR (400 MHz, CDCl3=TMS): d 0.90 (t, J ¼ 7.0 Hz, 3 H, Me), 1.34–1.56
(m, 4 H, 2 ꢃ CH2), 1.66 (d, J ¼ 6.9 Hz, 3 H, Me), 2.44 (t, J ¼ 7.5 Hz, 2 H, SCH2),
3.89 (q, J ¼ 6.9 Hz, 1 H, SCH), 7.07–7.49 (m, 5 Harom); 13C NMR (100 MHz,
CDCl3=TMS): d 14.1, 22.7, 23.9, 29.5, 31.2, 42.1, 127.2, 128.7, 129.5, 138.2. MS
(EI): m=z ¼ 194 [Mþ]. Anal. calcd. for C12H18S: C, 74.16; H, 9.34. Found: C,
74.42; H, 8.97.
1-(1-Thiocyanatoethyl)benzene (Table 2, entry 3). Yield: 0.28 g (2 mmol,
87%); white crystals; mp 42–43 ꢄC; IR (KBr, cmꢂ1): 3070, 2915, 2145, 1600, 1582,
1475, 1450, 750, 700.1H NMR (400 MHz, CDCl3=TMS): d 1.98 (d, J ¼ 6.6 Hz, 3
H, Me), 4.85 (q, J ¼ 6.6 Hz, 1 H, SCH), 7.09–7.51 (m, 5 Harom); 13C NMR
(100 MHz, CDCl3=TMS): d 25.8, 44.4, 114.6, 128.8, 129.9, 133.1, 139.7; MS (EI):
m=z ¼ 163 [Mþ]. Anal. calcd. for C9H9NS: C, 66.22; H, 5.56; N, 8.58. Found:
C,66.54; H, 5.85; N, 8.25.
(1-(4-Methoxyphenyl)ethyl)(phenyl)sulfane (Table 2, entry 4). Yield:
0.45 g (2 mmol, 93%); white crystals; 39–40 ꢄC; IR (KBr, cmꢂ1): 3062, 2912, 1600,
1573, 1492, 1440, 835, 739, 700; 1H NMR (400 MHz, CDCl3=TMS): d 1.67 (d,
J ¼ 6.9 Hz, 3 H, Me), 3.73 (s, 3 H, OMe), 4.00 (q, J ¼ 6.9 Hz, 1 H, SCH), 6.80 (d,
J ¼ 8.5 Hz, 2 Harom), 7.08–7.50 (m, 7 Harom);13C NMR (100 MHz, CDCl3=TMS): d
24.1, 42.2, 54.6, 122.0, 124.3, 125.3, 126.5, 127.6, 129.0, 134.2, 139.2; MS (EI): m=
z ¼ 244 [Mþ]. Anal. calcd. for C15H16OS: C, 73.73; H, 6.60. Found: C, 73.42; H, 6.78.
Butyl(1-(4-methoxyphenyl)ethyl)sulfane (Table 2, entry 5). Yield: 0.41 g
(2 mmol, 92%); colorless liquid; IR (neat, cmꢂ1): 3052, 2901, 1605, 1580, 1475,
1435, 820;1H NMR (400 MHz, CDCl3=TMS): d 0.89 (t, J ¼ 7.1 Hz, 3 H, Me),

SULFENYLATION AND THIOCYANATION OF CARBONYLS
107
1.33–1.55 (m, 4 H, 2 ꢃ CH2), 1.65 (d, J ¼ 7.0 Hz, 3 H, Me), 2.43 (t, J ¼ 7.6 Hz, 2 H,
SCH2), 3.73 (s, 3 H, OMe), 3.88 (q, J ¼ 7.0 Hz, 1 H, SCH), 6.79 (d, J ¼ 8.6 Hz, 2
H
arom), 7.07–7.49 (d, J ¼ 8.6 Hz, 2 Harom);13C NMR (100 MHz, CDCl3=TMS): d
14.2, 22.6, 24.0, 29.4, 31.3, 42.0, 54.8, 127.0, 128.6, 129.6, 138.1; MS (EI): m=
z ¼ 224 [Mþ]. Anal. calcd. for C13H20OS: C, 69.59; H, 8.98. Found: C, 69.78; H, 8.74.
1-Methoxy-4-(1-thiocyanatoethyl)benzene (Table 2, entry 6). Yield:
0.35 g (2 mmol, 90%); white crystals; mp 44–45 ꢄC; IR (KBr, cmꢂ1): 3054, 2902,
2140, 1600, 1583, 1500, 1452, 835;1H NMR (400 MHz, CDCl3=TMS): d 1.97 (d,
J ¼ 6.3 Hz, 3 H, Me), 3.73 (s, 3 H, OMe), 4.84 (q, J ¼ 6.3 Hz, 1 H, SCH), 6.81 (d,
J ¼ 8.4 Hz, 2 Harom), 7.09–7.51 (d, J ¼ 8.4 Hz, 2 Harom);13C NMR (100 MHz,
CDCl3=TMS): d 25.9, 44.3, 54.8, 111.4, 128.9, 129.8, 133.0, 139.8; MS (EI): m=
z ¼ 193 [Mþ]. Anal. calcd. for C10H11NOS: C, 62.15; H, 5.74; N, 7.25. Found: C,
61.96; H, 5.37; N, 7.54.
(1-(4-Chlorophenyl)ethyl)(phenyl)sulfane (Table 2, entry 7). Yield: 0.44 g
(2 mmol, 88%); white crystals; mp 43–44 ꢄC; IR (KBr, cmꢂ1): 3080, 2925, 1600, 1578,
1505, 856, 753, 698;1H NMR (400 MHz, CDCl3=TMS): d 1.70 (d, J ¼ 6.7 Hz,
3 H, Me), 4.05 (q, J ¼ 6.7 Hz, 1 H, SCH), 7.10–7.66 (m, 9 Harom);13C NMR
(100 MHz, CDCl3=TMS): d 24.2, 42.6, 122.2, 124.0, 125.5, 126.3, 127.8, 128.9,
134.4, 139.2; MS (EI): m=z ¼ 248 [Mþ]. Anal. calcd. for C14H13ClS: C, 67.59; H,
5.27. Found: C, 67.33; H, 5.57.
Butyl(1-(4-chlorophenyl)ethyl)sulfane (Table 2, entry 8). Yield: 0.39 g
(2 mmol, 86%); colorless liquid; IR (neat, cmꢂ1): 3060, 2904, 1602, 1570, 1490,
1442, 845;1H NMR (400 MHz, CDCl3=TMS): d 0.91 (t, J ¼ 6.9 Hz, 3 H, Me),
1.35–1.57 (m, 4 H, 2 ꢃ CH2), 1.70 (d, J ¼ 7.1 Hz, 3 H, Me), 2.45 (t, J ¼ 7.4 Hz, 2
H, SCH2), 3.91 (q, J ¼ 7.1 Hz, 1 H, SCH), 7.09–7.65 (m, 4 Harom);13C NMR
(100 MHz, CDCl3=TMS): d 14.0, 22.8, 24.2, 29.6, 31.3, 42.2, 127.3, 128.9, 129.4,
138.6; MS (EI): m=z ¼ 228 [Mþ]. Anal. calcd. for C12H17ClS: C, 63.00; H, 7.49.
Found: C, 62.78; H, 7.81.
1-Chloro-4-(1-thiocyanatoethyl)benzene (Table 2, entry 9). Yield: 0.33 g
(2 mmol, 85%); white crystals; mp 46–47 ꢄC; IR (KBr, cmꢂ1): 3085, 2925, 2158,
1
1602, 1579, 1508, 1450, 860, 755, 703; H NMR (400 MHz, CDCl3=TMS): d 2.00
(d, J ¼ 6.1 Hz, 3 H, Me), 4.86 (q, J ¼ 6.1 Hz, 1 H, SCH), 7.11–7.67 (m, 4 Harom);13C
NMR (100 MHz, CDCl3=TMS): d 26.0, 44.6, 114.6, 128.9, 129.9, 133.0,139.9; MS
(EI): m=z ¼ 197 [Mþ]. Anal. calcd. for C9H8ClNS: C, 54.68; H, 4.08; N, 7.09. Found:
C, 54.40; H, 4.23; N, 7.43.
(But-3-en-2-yl)(phenyl)sulfane (Table 2, entry 10). Yield: 0.27 g (2 mmol,
83%); colorless liquid; IR (neat, cmꢂ1): 2970, 1600, 1645, 1574, 1500, 1446, 995,
1
920, 745, 700; H NMR (400 MHz, CDCl3=TMS): d 1.30 (d, J ¼ 7.9 Hz, 3 H, Me),
=
3.30 (qd, J ¼ 8.9 Hz, 7.9 Hz, 1 H, SCH), 4.97 (dd, J ¼ 17.2, 1.6 Hz, 1 H, CH2),
=
4.98 (dd, J ¼ 10.6, 1.6 Hz, 1 H, CH2), 5.70 (ddd, J ¼ 17.2, 10.6, 8.9 Hz, 1 H,
CH), 7.06–7.48 (m, 5 Harom); 13C NMR (100 MHz, CDCl3=TMS): d 24.8, 43.0,
=
117.2, 126.4, 128.1, 130.0, 135.2, 136.0; MS (EI): m=z ¼ 164 [Mþ]. Anal. calcd. for
C10H12S: C, 73.12; H, 7.36. Found: C, 72.96; H, 6.99.

108
L. D. S. YADAV, GARIMA, AND R. KAPOOR
(But-3-en-2-yl)(butyl)sulfane (Table 2, entry 11). Yield: 0.24 g (2 mmol,
82%); colorless liquid; IR (neat, cmꢂ1): 2951, 1636, 992, 915;1H NMR (400 MHz,
CDCl3=TMS): d 0.89 (t, J ¼ 7.1 Hz, 3 H, Me), 1.29 (d, J ¼ 7.8 Hz, 3 H, Me),
1.33–1.55 (m, 4 H, 2 ꢃ CH2), 2.43 (t, J ¼ 7.4 Hz, 2 H, SCH2), 3.29 (qd, J ¼ 8.8,
=
7.8 Hz, 1 H, SCH), 4.96 (dd, J ¼ 17.1, 1.5 Hz, 1 H, CH2), 4.97 (dd, J ¼ 10.5,
13
=
=
1.5 Hz, 1 H, CH2), 5.69 (ddd, J ¼ 17.1, 10.5, 8.8 Hz, 1 H, CH); C NMR
(100 MHz, CDCl3=TMS): d 14.0, 18.0, 22.4, 25.0, 31.5, 35.0, 42.3, 135.0; MS (EI):
m=z ¼ 144 [Mþ]. Anal. calcd. for C8H16S: C, 66.60; H, 11.18. Found: C, 66.31; H,
11.49.
Benzyl(phenyl)sulfane (Table 2, entry 12). Yield: 0.35 g (2 mmol, 87%);
pale yellow crystals; mp 41–42 ꢄC (lit.[25] mp 40–41 ꢄC); IR (KBr, cmꢂ1): 3070,
2922, 1600, 1573, 1505, 1445, 762, 700;1H NMR (400 MHz, CDCl3=TMS): d 3.99
(s, 2 H, SCH2), 7.02–7.44 (m, 10 Harom);13C NMR (100 MHz, CDCl3=TMS): d
39.6, 122.0, 124.1, 125.0, 126.1, 127.9, 128.7, 134.0, 141.2; MS (EI): m=z ¼ 200
[Mþ]. Anal. Calcd. for C13H12S: C, 77.95; H, 6.04. Found: C, 78.32; H, 5.73.
Benzyl(butyl)sulfane (Table 2, entry 13). Yield: 0.32 g (2 mmol, 88%); col-
orless liquid; IR (neat, cmꢂ1): 3060, 2930, 1599, 1575, 1495, 1450, 765, 695;1H NMR
(400 MHz, CDCl3=TMS): d 0.89 (t, J ¼ 7.1 Hz, 3 H, Me), 1.33–1.55 (m, 4 H,
2 ꢃ CH2), 2.43 (t, J ¼ 7.5 Hz, 2 H, SCH2), 3.85 (s, 2 H, SCH2), 7.01–7.43 (m, 5
H
arom);13C NMR (100 MHz, CDCl3=TMS): d 14.0, 22.5, 29.0, 31.4, 39.2 127.2,
128.8, 129.3, 137.0; MS (EI): m=z ¼ 180 [Mþ]. Anal. calcd. for C11H16S: C, 73.27;
H, 8.94. Found: C, 73.00; H, 8.68.
1-(Thiocyanatomethyl)benzene (Table 2, entry 14). Yield: 0.26 g (2 mmol,
86%); pale yellow crystals; mp 40–41 ꢄC (lit.[26] mp 39–40 ꢄC); IR (KBr, cmꢂ1): 3082,
1
2925, 2155, 1602, 1576, 1508, 1455, 760, 700; H NMR (400 MHz, CDCl3=TMS): d
4.81 (s, 2 H, SCH2), 7.03–7.45 (m, 5 Harom);13C NMR (100 MHz, CDCl3=TMS): d
38.7, 112.2, 129.4, 129.6, 132.6, 134.8; MS (EI): m=z ¼ 149 [Mþ]. Anal. calcd. for
C8H7NS: C, 64.39; H, 4.73; N, 9.39. Found: C, 64.76; H, 4.48; N, 9.72.
(4-Methoxybenzyl)(phenyl)sulfane (Table 2, entry 15). Yield: 0.41 g
(2 mmol, 89%); colorless liquid; IR (neat, cmꢂ1): 3050, 2930, 1600, 1575, 1490,
1
1445, 845, 755, 705; H NMR (400 MHz, CDCl3=TMS): d 3.73 (s, 3 H, OMe),
3.96 (s, 2 H, SCH2), 6.75 (d, J ¼ 8.7 Hz, 2 Harom), 7.02–7.44(m, 7 Harom);13C
NMR (100 MHz, CDCl3=TMS): d 38.4, 54.7, 122.2, 124.4, 125.1, 126.4, 127.8,
129.2, 134.1, 139.0; MS (EI): m=z ¼ 230 [Mþ]. Anal. calcd. for C14H14OS: C,
73.01; H, 6.13. Found: C, 72.78; H, 6.35.
(4-Methoxybenzyl)(butyl)sulfane (Table 2, entry 16). Yield: 0.36 g
(2 mmol, 86%); colorless liquid; IR (neat, cmꢂ1): 3055, 2930, 1602, 1578, 1500,
1452, 860; 1H NMR (400 MHz, CDCl3=TMS): d 0.88 (t, J ¼ 7.2 Hz, 3 H, Me),
1.32–1.54 (m, 4 H, 2 ꢃ CH2), 2.42 (t, J ¼ 7.6 Hz, 2 H, SCH2), 3.73 (s, 3 H, OMe),
3.84 (s, 2 H, SCH2), 6.74 (d, J ¼ 8.8 Hz, 2 Harom), 7.01–7.43 (d, J ¼ 8.8 Hz, 2 H,
ArCH); 13C NMR (100 MHz, CDCl3=TMS): d 14.3, 22.6, 29.5, 31.3, 38.2, 54.7,
127.0, 128.5, 129.6, 138.1; MS (EI): m=z ¼ 210 [Mþ]. Anal. calcd. for C12H18OS:
C, 68.52; H, 8.63. Found: C, 68.78; H, 8.43.

SULFENYLATION AND THIOCYANATION OF CARBONYLS
109
1-Methoxy-4-(thiocyanatomethyl)benzene (Table 2, entry17). Yield:
0.31 g (2 mmol, 87%); colorless liquid; IR (neat, cmꢂ1): 3070, 2920, 2145, 1605,
1576, 1510, 1455, 840;1H NMR (400 MHz, CDCl3=TMS): d 3.73 (s, 3 H, OMe),
4.80 (s, 2 H, SCH2), 6.78 (d, J ¼ 8.7 Hz, 2 Harom), 7.03–7.45 (d, J ¼ 8.6 Hz, 2 Harom);
13C NMR (100 MHz, CDCl3=TMS): d 38.7, 54.9, 114.7,128.9, 129.8, 133.2, 139.9;
MS (EI): m=z ¼ 179 [Mþ]. Anal. Calcd. for C9H9NOS: C, 60.31; H, 5.06; N, 7.81.
Found: C, 60.00; H, 5.27; N, 7.51.
(4-Chlorobenzyl)(phenyl)sulfane (Table 2, entry 18). Yield: 0.39 g
(2 mmol, 83%); colorless liquid; IR (neat, cmꢂ1): 3075, 2925, 1605, 1578, 1500,
1450, 830;1H NMR (400 MHz, CDCl3=TMS): d 4.01 (s, 2 H, SCH2), 7.04–7.60
(m, 9 Harom);13C NMR (100 MHz, CDCl3=TMS): d 38.3, 123.2, 124.5, 125.3,
126.8, 127.8, 129.2, 133.7, 137.8; MS (EI): m=z ¼ 234 [Mþ]. Anal. calcd. for
C13H11ClS: C, 66.51; H, 4.72. Found: C, 66.78; H, 4.52.
(4-Chlorobenzyl)(butyl)sulfane (Table 2, entry 19). Yield: 0.35 g (2 mmol,
1
82%); colorless liquid; IR (neat, cmꢂ1): 3065, 2910, 1600, 1575, 1504, 1445, 855; H
NMR (400 MHz, CDCl3=TMS): d 0.90 (t, J ¼ 7.0 Hz, 3 H, Me), 1.34–1.56 (m, 4 H,
2 ꢃ CH2), 2.44 (t, J ¼ 7.5 Hz, 2 H, SCH2), 3.87 (s, 2 H, SCH2), 7.03–7.59 (m, 4
H
arom); 13C NMR (100 MHz, CDCl3=TMS): d 14.0, 22.8, 29.2, 32.2, 38.6, 127.3,
128.9, 129.2, 136.2; MS (EI): m=z ¼ 214 [Mþ]. Anal. calcd. for C11H15ClS: C,
61.52; H, 7.04. Found: C, 61.74; H, 6.86.
1-Chloro-4-(thiocyanatomethyl)benzene (Table 2, entry 20). Yield:
0.29 g (2 mmol, 78%); pale yellow crystals; mp 40–41 ꢄC; IR (KBr, cmꢂ1): 3080,
2925, 2152, 1603, 1580, 1520, 1452, 835;1H NMR (400 MHz, CDCl3=TMS): d 4.82
(s, 2 H, SCH2), 7.05–7.61 (m, 4 Harom);13C NMR (100 MHz, CDCl3=TMS): d
38.9, 114.9, 128.9, 129.6, 133.2, 138.2; MS (EI): m=z ¼ 183 [Mþ]. Anal. calcd. for
C8H6ClNS: C, 52.32; H, 3.29; N, 7.63. Found: C, 52.64; H, 3.01; N, 7.43.
Allyl(phenyl)sulfane (Table 2, entry 21). Yield: 0.24 g (2 mmol, 81%); color-
1
less liquid; IR (neat, cmꢂ1): 2980, 1630, 1600, 1574, 1500, 1446, 990, 925, 745; H
NMR (400 MHz, CDCl3=TMS): d 3.32 (d, J ¼ 7.6 Hz, 2 H, SCH2), 5.09 (dd,
=
=
J ¼ 10.7, 1.4 Hz, 1 H, CH2), 5.14 (dd, J ¼ 17.9, 1.4 Hz, 1 H, CH2), 5.89 (tdd,
J ¼ 17.9, 10.7, 7.6 Hz, 1 H, CH), 7.20–7.60 (m, 5 Harom);13C NMR (100 MHz,
=
CDCl3=TMS): d 37.9, 116.6, 124.4, 126.9, 128.9, 134.5, 135.2: MS (EI): m=z ¼ 150
[Mþ]. Anal. calcd. for C9H10S: C, 71.95; H, 6.71. Found: C, 71.78; H, 6.52.
Allyl(butyl)sulfane (Table 2, entry 22). Yield: 0.21 g (2 mmol, 83%); color-
1
less liquid; IR (neat, cmꢂ1): 2953, 1634, 995, 918; H NMR (400 MHz, CDCl3=
TMS): d 0.90 (t, J ¼ 6.9 Hz, 3 H, Me), 1.33–1.54 (m, 4 H, 2 ꢃ CH2), 2.45 (t,
J ¼ 7.4 Hz, 2 H, SCH2), 3.12 (d, J ¼ 7.3 Hz, 2 H, SCH2), 5.07 (dd, J ¼ 10.6, 1.3 Hz,
=
=
1 H, CH2), 5.08 (dd, J ¼ 16.2, 1.3 Hz, 1 H, CH2), 5.79 (tdd, J ¼ 16.2, 10.6,
7.3 Hz, 1 H, CH); 13C NMR (100 MHz, CDCl3=TMS): d 13.8, 22.2, 29.8, 31.2,
=
34.6, 116.4, 134.5; MS (EI): m=z ¼ 130 [Mþ]. Anal. calcd. for C7H14S: C, 64.55; H,
10.83; Found: C, 64.84; H, 11.13.

110
L. D. S. YADAV, GARIMA, AND R. KAPOOR
ACKNOWLEDGMENTS
We sincerely thank SAIF, CDRI, Lucknow, for providing microanalyses and
spectra. Two of the authors (Garima and R. Kapoor) are grateful to the Council
of Scientific Industrial Research, New Delhi, for the award of a junior research
fellowship and research associate fellowship, respectively.
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