Sulfonated porous carbon catalyzed direct and efficient conversion of tertiary, allylic, and benzylic alcohols to thioesters

Article abstract of DOI:10.1080/17415993.2012.684204

A one-pot conversion of alcohols to thioesters using a sulfonated porous carbon (SPC) as a solid acid catalyst is reported. It was found that, when a tertiary, benzylic, or allylic alcohol was reacted with thioamides in the presence of SPC, the corresponding thioesters were produced in good to excellent yields in a short time.

Full text of DOI:10.1080/17415993.2012.684204

Journal of Sulfur Chemistry
Vol. 33, No. 3, June 2012, 285–293
Sulfonated porous carbon catalyzed direct and efficient
conversion of tertiary, allylic, and benzylic alcohols to thioesters
Hassan Zali-Boeini* and Aida Khajeh
Department of Chemistry, University of Isfahan, 81746-73441 Isfahan, Iran
(Received 11 March 2012; final version received 6 April 2012)
A one-potconversion of alcoholsto thioestersusingasulfonated porous carbon(SPC)asa solid acidcatalyst
is reported. It was found that, when a tertiary, benzylic, or allylic alcohol was reacted with thioamides in
the presence of SPC, the corresponding thioesters were produced in good to excellent yields in a short
time.
Keywords: acid derivatives; alcohol; thioamide; carbocations; sulfonated porous carbon
1. Introduction
It is well known that thioesters are important compounds due to the large number of biological
activities that they exhibit (1–4) and due to their huge potential for drug development (5–9) and
industrial (10–12) applications. In addition, thioesters exhibit quite different chemical properties
in comparison to the corresponding oxoesters (13) and they have been successfully used in a vast
number of organic syntheses as useful intermediates (14).
The best-known approaches to the synthesis of thioesters are concisely reviewed in our recently
publishedarticleconcerningthesynthesisofthioestersinwater(15). Morerecently, thioestershave
also been prepared by the reaction of thioamides and alcohols in acidic media (16). However, these
methods suffer from the use of large amounts of thioamide or alcohol and acid (1–10 equivalents)
and long reaction times (24 h).
It is well established that thioamides are versatile and highly successful synthons that have seen
tremendous use in the construction of sulfur-containing heterocyclic compounds (17). In order
to increase the yield of thioesters and to avoid the use of corrosive and expensive reagents or
catalysts and unfriendly organic solvents, we have examined a sulfonated porous carbon (SPC)
*Corresponding author. Email: h.zali@chem.ui.ac.ir
ISSN 1741-5993 print/ISSN 1741-6000 online
© 2012 Taylor & Francis
http://dx.doi.org/10.1080/17415993.2012.684204
http://www.tandfonline.com

286 H. Zali-Boeini and A. Khajeh
solid acid for the preparation of thioesters from alcohols. Herein, we describe the results of this
study that has produced a straightforward and versatile method for the catalytic conversion of
alcohols to thioesters using tertiary thioamides and an SPC catalyst (Scheme 1).
Scheme 1. Efficient synthesis of thioesters catalyzed by SPC solid acid.
2. Results and discussion
SPC catalysts have been found to be highly efficient, eco-friendly, and recyclable heterogeneous
acid catalysts for a wide variety of organic reaction types (18). They have many advantages such
as insolubility in polar solvents, recyclability, low corrosion, environmental acceptability, and
ease of product separation. Therefore, they are an attractive alternative to sulfuric acid as catalysts
in various organic reactions. The tertiary thioamides used in this study could be easily prepared
by the Willgerodt–Kindler reaction or other suitable methods (19). Our study started with the
examination of the reaction of benzyl alcohol 1 with phenyl(morpholino)methanethione 2 as a
test tertiary thioamide under various reaction conditions to produce the corresponding S-benzyl
benzothioate 3a (Table 1).
DMF was used at the outset of our study as the solvent for the reaction. Therefore, a mixture of
phenyl(morpholino) methanethione, benzyl alcohol, and catalytic amounts of p-TsOH (20 mol%)
was dissolved in small amounts of DMF and the reaction mixtures were heated at 100◦C for
90 min. Subsequently, the reaction mixtures were poured into a mixture of ice water to deposit the
crude thioester as a semisolid material which, after crystallization in a suitable solvent (EtOH),
gave the pure compound 3a in low yield (36%). In addition to p-TsOH and DMF, other acids and
solvents were also examined as reaction media and the screening results showed a remarkable
increase in the yield of the thioester in polar solvents (Table 1). As shown in Table 1, the best
Table 1. Screening of the temperature and catalyst in the synthesis of thioester 3a.a
Yield (%)
Entry
1
Solvent
Acid catalyst
Time (min)
T (100◦C)
T (120◦C)b
DMF
AcOH
Toluene
Solvent-free
DMF
AcOH
Toluene
Solvent-free
p-TsOH
p-TsOH
p-TsOH
p-TsOH
CF3SO3H
CF3SO3H
CF3SO3H
SPC
90
90
90
90
90
90
90
45
36
45
24
52
58
64
47
85
32
34c
22c
49
2
3
41
47c
31c
73
Notes: aThioamide (1 mmol), alcohol (1 mmol), SPC (0.2 g).
bFormation of colored and/or tarry materials was observed.
cIn reflux conditions.

Journal of Sulfur Chemistry 287
Table 2. Efficient synthesis of thioesters using alcohols.
Entry
R
Ar
Producta
Yield (%)b
O
S
1
4-Nitrobenzyl
Ph
85
NO2
3a
O
S
2
3
4-Nitrobenzyl
4-Nitrobenzyl
4-Tolyl
4-ClPh
81
NO2
Me
3b
O
S
79
NO2
Cl
3c
O
S
4
5
4-Nitrobenzyl
4-Nitrobenzyl
4-Biphenyl
2-Naphthyl
87
NO2
3d
O
77
S
NO2
3e
O
S
6
4-Nitrobenzyl
4-i-PrPh
76
Me
NO2
Me
3f
O
MeO
MeO
S
7
8
9
4-Nitrobenzyl
3,4-diMeOPh
4-Biphenyl
2-Naphthyl
75
NO2
3g
O
S
Benzyl
87
3h
O
S
Benzyl
75
3i
(Continued)

288 H. Zali-Boeini and A. Khajeh
Table 2. Continued.
Entry
R
Ar
Producta
Yield (%)b
O
S
10
4-Chlorobenzyl
2-Naphthyl
71
Cl
3j
O
11
12
t-Butyl
2-Naphthyl
67
88
S
3k
O
S
Benzhydryl
4-Tolyl
Me
3l
O
S
13
14
15
Benzhydryl
3,4-diMeOPh
3,4-diMeOPh
2-Naphthyl
84
71
69
MeO
MeO
3m
O
MeO
MeO
Allyl
S
3n
O
Allyl
S
3o
O
S
16
17
1-Adamantyl
1-Adamantyl
Ph
90
3p
O
S
4-Tolyl
94
Me
3q
(Continued)

Journal of Sulfur Chemistry 289
Table 2. Continued.
Entry
R
Ar
Producta
Yield (%)b
O
S
18
1-Adamantyl
4-CPh
90
Cl
3r
O
S
19
20
1-Adamantyl
1-Adamantyl
4-i-PrPh
88
3s
O
OMe
OMe
S
3,4-diMeOPh
89
3t
Notes: aAll products were characterized by melting points, IR, 1H NMR, and 13C NMR.
bAll yields refer to pure isolated products.
result was obtained when the reaction was performed with SPC as the catalyst under solvent-free
conditions. It is worthwhile to note that increasing the reaction time and the reaction temperature
does not cause an increase in the yield of thioesters. In fact, it is clear that increasing reaction time
and temperature is detrimental and leads to product mixtures contaminated with some colored
and/or tarry materials. It was also found that SPC increased the rate of reaction by approximately
a factor of 2 in addition to producing the highest product yield.
With these results in hand, we chose to use SPC under solvent-free conditions to examine the
reactions of the 20 different combinations of substituted thioamides and alcohols as shown in
Table 2. These reactions lead to a variety of different thioesters in good to excellent yields (67–
94%) in a short reaction time (45 min). The results in Table 2 also demonstrate that the method
works better with alcohols that can generate a stable carbocation. Furthermore, as expected no
reaction occurred when the reactants were heated at a variety of temperatures in the absence of
an acid catalyst.
The mechanism we propose to explain the role of SPC as catalyst in these reactions is shown
in Scheme 2. In this mechanism, alcohol 1 is first protonated with the aid of the carbon-base solid
acid and then fragments to generate a carbocation intermediate which then undergoes nucleophilic
attack by thioamide 2 generate the thiouronium salt 4. Subsequent hydrolysis of this intermediate
affords the corresponding thioester 3 along with the elimination of morpholine.
3. Conclusions
In conclusion, we have presented here a simple methodology for the conversion of alcohols to
thioesters under solvent-free conditions in the presence of an SPC catalyst, which is expected to be
a general route for the synthesis of diverse thioesters. Besides being an efficient, easy to perform,
and environmentally benign reaction, the method benefits from the use of cheap and safe starting

290 H. Zali-Boeini and A. Khajeh
Scheme 2. A proposed mechanism for the conversion of alcohols to thioesters.
materials. In addition, isolation and purification of the product is straightforward and the SPC
catalyst is recoverable and the recovered catalyst can be used repeatedly without deactivation.
4. Experimental section
The SPC used in this study was prepared according to a reported procedure (20).
General procedure for the conversion of alcohols to thioesters under solvent-free conditions.
Thioamide (1 mmol), alcohol (1.2 mmol), and SPC (0.2 g) were mixed in a round bottom flask
and heated to 100◦C for 45 min. The reaction mixture was then poured into hot EtOH (95%)
(15 ml) and the precipitated SPC catalyst was filtered. Finally, the solution was slowly cooled to
room temperature and the resulting crystals filtered and washed with ice-cold EtOH (95%) (5 ml)
to afford the pure thioesters as white or pale yellow needles.
(3a): Light yellow crystals; mp (MeOH): 93–94◦C; H NMR (400 MHz, CDCl3): δ 8.19 (d,
1
J = 8.8 Hz, 2H), 7.97 (d, d, J = 8.5 Hz, J = 1.3 Hz, 2H), 7.61 (t, J = 7.5 Hz, 1H), 7.58 (d,
J = 8.8, 2H), 7.48 (t, J = 7.5, 2H), 4.38 (s, 2H); 13C NMR (100 MHz, CDCl3): δ 190.5, 147.1,
145.6, 136.3, 133.9, 129.9, 128.8, 127.4, 124.0, 32.6; Anal. Calcd. for C14H11NO3S: C, 61.52; H,
4.06; N, 5.12; S, 11.73. Found: C, 61.48; H, 3.95; N, 5.23; 11.81.
1
(3b): Light yellow crystals; mp (MeOH): 102–103◦C; H NMR (400 MHz, CDCl3): δ 8.21 (d,
J = 8.9 Hz, 2H), 7.86 (d, J = 8.2 Hz, 2H), 7.56 (d, J = 8.9 Hz, 2H), 7.27 (d, J = 8.2 Hz, 2H),
4.36 (s, 2H), 2.42 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 190.0, 147.1, 145.8, 144.9, 133.7,
130.1, 129.2, 127.5, 123.8, 32.4, 21.9; Anal. Calcd. for C15H13NO3S: C, 62.70; H, 4.56; N, 4.87;
S, 11.16. Found: C, 62.53; H, 4.43; N, 5.01; S, 11.28.

Journal of Sulfur Chemistry 291
1
(3c): Light yellow crystals; mp (MeOH): 118–119◦C; H NMR (400 MHz, CDCl3): δ 8.19 (d,
J = 8.7 Hz, 2H), 7.91 (d, J = 8.6 Hz, 2H), 7.57 (d, J = 8.7 Hz, 2H), 7.45 (d, J = 8.6 Hz, 2H),
4.38 (s, 2H); 13C NMR (100 MHz, CDCl3): δ 189.3, 147.2, 145.2, 140.3, 134.6, 129.9, 129.1,
128.7, 123.9, 32.6; Anal. Calcd. for C14H10ClNO3S: C, 54.64; H, 3.28; N, 4.55; S, 10.42. Found:
C, 54.45; H, 3.19; N, 4.71; S, 10.61.
1
(3d): Light yellow crystals; mp (MeOH): 150–151◦C; H NMR (400 MHz, CDCl3): δ 8.20 (d,
J = 8.7 Hz, 2.H), 8.05 (d, J = 8.5 Hz, 2H), 7.71 (d, 8.5 Hz, 2H), 7.64 (d, J = 5.2 Hz, 2H), 7.59 (d,
J = 8.7 Hz, 2H), 7.50 (t, J = 6.8, 2H), 7.44 (t, J = 7.3, 1H), 4.41 (s, 2H); 13C NMR (100 MHz,
CDCl3): δ 190.0, 147.1, 146.6, 145.6, 139.6, 134.9, 129.9, 129.0, 128.5, 128.0, 127.6, 127.3,
123.9, 32.6; Anal. Calcd. for C20H15NO3S: C, 68.75; H, 4.33; N, 4.01; S, 9.18. Found: C, 68.61;
H, 4.14; N, 4.11; S, 9.30.
1
(3e): Light yellow crystals; mp (MeOH): 127–128◦C; H NMR (400 MHz, CDCl3): δ 8.54 (s,
1H), 8.20 (d, J = 8.6 Hz, 2H), 7.99 (t, J = 9.6 Hz, 2H), 7.90 (t, J = 8.3 Hz, 2H), 7.57–7.65 (m,
4H), 4.43 (s 2H); 13C NMR (100 MHz, CDCl3): δ 190.3, 147.2, 145.6, 136.0, 133.6, 132.4, 129.9,
129.6, 129.1, 128.8, 128.7, 127.9, 127.1, 123.9, 123.0, 32.7; Anal. Calcd. for C18H13NO3S: C,
66.86; H, 4.05; N, 4.33; S, 9.92. Found: C, 66.61; H, 3.98; N, 4.45; S, 10.02.
1
(3f): Light yellow crystals; mp (MeOH): 100–102◦C; H NMR (400 MHz, CDCl3): δ 8.18 (d,
J = 9.3 Hz, 2H), 7.91 (d, J = 8.3 Hz, 2H), 7.57 (d, J = 8.7 Hz, 2H), 7.33 (d, J = 8.3 Hz, 2H),
4.37 (s, 2H), 2.97 (sep, J = 6.9 Hz, 1H), 1.28 (d, J = 7.0 Hz, 6H); 13C NMR (100 MHz, CDCl3):
δ 190.0, 155.6, 147.1, 145.8, 134.1, 129.8, 127.6, 126.9, 123.8, 34.3, 32.4, 32.6; Anal. Calcd.
for C17H17NO3S: C, 64.74; H, 5.43; N, 4.44; S, 10.17. Found: C, 64.62; H, 5.32; N, 4.60; S,
10.29.
(3g): Light yellow crystals; mp (MeOH): 104–106◦C; H NMR (400 MHz, CDCl3): δ 8.15 (d,
1
J = 8.6 Hz, 2H), 7.63 (d, d, J = 8.5 Hz, J = 1.9 Hz, 1H), 7.54 (d, J = 8.6 Hz, 2H), 7.44 (d,
J = 1.9 Hz, 1H), 6.89 (d, J = 8.5 Hz, 1H), 4.34 (s, 2H), 3.94 (s, 3H), 3.92 (s, 3H); 13C NMR
(100 MHz, CDCl3): δ 189.1, 153.8, 149.0, 147.1, 145.8, 130.0, 129.2, 123.8, 122.0, 110.3, 109.4,
56.2, 56.0, 32.5; Anal. Calcd. for C16H15NO5S: C, 57.65; H, 4.54; N, 4.20; S, 9.62. Found: C,
57.57; H, 4.41; N, 4.42; S, 9.75.
(3h): White crystals; mp (MeOH): 74–76◦C; 1H NMR (400 MHz, CDCl3): δ 8.09 (d, J = 8.3 Hz,
2H), 7.71 (d, J = 8.3 Hz, 2H), 7.66 (d, J = 7.3 Hz, 2H), 7.51 (d, J = 7.4 Hz, 2H), 7.43–7.46
(m, 3H), 7.38 (t, J = 7.4 Hz, 2H), 7.31 (t, J = 7.2 Hz, 1H), 4.40 (s, 2H); 13C NMR (100 MHz,
CDCl3): δ 190.9, 146.2, 139.8, 137.6, 135.5, 129.1, 129.0, 128.9, 128.7, 128.4, 127.9, 127.4,
127.3, 33.4; Anal. Calcd. for C20H16OS: C, 78.91; H, 5.30; S, 10.53. Found: C, 78.77; H, 5.11;
S, 10.76.
(3i): White crystals; mp (MeOH): 75–77◦C; 1H NMR (400 MHz, CDCl3): δ 8.58 (s, 1H), 8.04 (d,
d, J = 8.6 Hz, J = 1.5 Hz, 1H), 7.98 (d, J = 8.0 Hz, 1H), 7.90 (t, J = 8.3 Hz, 2H), 7.56–7.64 (m,
2H), 7.46 (d, J = 7.3 Hz, 2H), 7.38 (t, J = 7.6 Hz, 2H), 7.31 (t, J = 7.1 Hz, 1H), 4.42 (s, 2H);
13C NMR (100 MHz, CDCl3): δ 191.3, 137.6, 135.8, 134.1, 132.5, 129.6, 129.1, 128.8, 128.7,
128.6, 127.8, 127.4, 127.0, 125.9, 123.2, 33.5; Anal. Calcd. for C18H14OS: C, 77.66; H, 5.07; S,
11.52. Found: C, 77.55; H, 5.01; S, 11.65.
1
(3j): White crystals; mp (MeOH): 62–64◦C; H NMR (400 MHz, CDCl3): δ 8.56 (s, 1H) 8.02
(d, d, J = 8.6 Hz, J = 1.7 Hz, 1H), 8.97 (d, J = 8.0 Hz, 1H), 7.90 (t, J = 8.3 Hz, 2H), 7.56–7.64
(m, 2H), 7.40 (t, J = 4.6 Hz, 2H), 7.04 (t, J = 8.7 Hz, 2H), 4.37 (s, 2H); 13C NMR (100 MHz,
CDCl3): δ 191.1, 163.3, 160.9, 135.8, 134.0, 130.7, 130.6, 129.6, 128.8, 128.6, 127.8, 127.0,
123.1, 115.7, 115.4, 32.7; Anal. Calcd. For C18H13ClOS: C, 69.11; H, 4.19; Cl, 11.33; S, 10.25.
Found: C, 69.02; H, 4.23; Cl, 11.37; S, 10.20.

292 H. Zali-Boeini and A. Khajeh
(3k): White crystals; mp (EtOH): 48◦C 1H NMR (400 MHZ, CDCl3): δ 8.50 (s, 1H), 7.94–7.96
(m, 2H), 7.87 (d, J = 8.4 Hz, 2H), 7.27 (m, 2H), 1.64 (s, 9H); 13C NMR (100 MHz, CDCl3):
δ 192.1, 162.5, 135.5, 132.4, 129.5, 128.3, 128.2, 127.7, 126.8, 125.2, 123.0, 48.2, 30.0; Anal.
Calcd. for C15H16OS: C, 73.73; H, 6.60; S, 13.12. Found: C, 73.96; H, 6.41; S, 12.98.
(3l): White crystals; mp (EtOH): 85–89◦C; 1H NMR (400 MHz, CDCl3): δ 7.27–7.42 (m, 14H),
5.40 (s, 1H), 2.40 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 189.8, 144.5, 142.3, 134.2, 129.4,
128.7, 128.6, 128.5, 127.6, 127.4, 51.9, 21.8; Anal. Calcd. for C21H18OS: C, 79.21; H, 5.70; S,
10.07. Found: C, 79.46; H, 5.48; S, 10.31.
(3m):White crystals; mp (EtOH): 96–100◦C; 1H NMR (400 MHz, CDCl3): δ 7.27–7.38 (m, 13H),
5.41 (s, 1H), 3.95 (s, 3H), 3.92 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 188.8, 153.6, 149.0, 142.3,
128.7, 128.6, 128.5, 127.4, 121.9, 110.3, 109.6, 56,1, 56.0, 52.0; Anal. Calcd. for C22H20O3S: C,
72.50; H, 5.53; S, 8.80. Found: C, 72.66; H, 5.29; S, 8.98.
1
(3n): White crystals; mp (EtOH): 46◦C H NMR (400 MHz, CDCl3): δ 7.57 (d, J = 8.4 Hz,
1H), 7.40 (s, 1H), 6.80 (d, J = 8.4 Hz, 1H), 5.83 (m, 1H), 5.25 (d, J = 6.8 Hz, 1H), 5.07 (d,
J = 9.6 Hz, 1H), 3.86 (s, 3H), 3.85 (s, 3H), 3.65 (d, J = 6.8 Hz, 2H); 13C NMR (100 MHz,
CDCl3): δ 189.6, 153.4, 148.8, 133.3, 130.8, 121.6, 117.8, 110.2, 109.3, 55.9, 55.7, 31.8; Anal.
Calcd. for C12H14O3S: C, 60.48; H, 5.92; S, 13.46. Found: C, 60.60; H, 5.79; S, 13.62.
1
(3o): White crystals; mp (EtOH): 52◦C H NMR (400 MHz, CDCl3): δ 8.55 (s, 1H), 7.99 (m,
2H), 7.89 (t, J = 7.0 Hz, 2H), 7.59 (m, 2H), 5.96 (m, 1H), 5.38 (d,d, J = 16.0 Hz, J = 1.0 Hz,
1H), 5.19 (d, J = 10.0 Hz, 1H), 3.81 (d, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3): δ 191.2,
135.8, 134.2, 133.2, 132.4, 131.2, 129.6, 128.7, 127.8, 126.9, 125.3, 123.2, 118.2, 32.0; Anal.
Calcd. for C14H12OS: C, 73.65; H, 5.30; S, 14.04. Found: C, 73.89; H, 5.19; S, 14.21.
(3p): White crystals; mp (EtOH):89–91◦C; 1H NMR (400 MHz, CDCl3): δ 7.92 (d, J = 7.6 Hz,
2H), 7.54 (t, J = 7.4 Hz, 1H), 7.43 (t, J = 7.4 Hz, 2H), 2.29 (s, 6H), 2.12 (s, 3H), 1.84 (d,
J = 12.6 Hz, 3H), 1.77 (d, J = 12.6 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 192.5, 138.4,
132.8, 128.4, 126.9, 51.1, 45.9, 36.4, 29.9; Anal. Calcd. for C17H20OS: C, 74.96; H, 7.40; O,
5.87; S, 11.77. Found: C, 75.22; H, 7.21; S, 11.91.
(3q): White crystals; mp (EtOH):110–111◦C; 1H NMR (400 MHz, CDCl3): δ 7.81 (d, J = 8.0 Hz,
2H), 7.21 (d, J = 8.0 Hz, 2H), 2.40 (s, 3H), 2.27 (d, J = 2.0 Hz, 6H), 2.10 (s, 3H), 1.83 (d,
J = 12.2 Hz, 3H), 1.75 (d, 12.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): δ 192.2, 143.6, 135.9,
129.1, 127.0, 50.9, 36.4, 36.1, 29,9, 21.6;Anal. Calcd. for C18H22OS: C, 75.48; H, 7.74; S, 11.19.
Found: C, 75.55; H, 7.61; S, 11.21.
(3r): White crystals; mp (EtOH):127–129◦C; 1H NMR (400 MHz, CDCl3): δ 7.86 (d, J = 7.6 Hz,
2H), 7.40 (d, J = 7.6 Hz, 2H), 2.27 (s, 6H), 2.11 (s, 3H), 1.83 (d, J = 12 Hz, 3H); 13C NMR
(100 MHz, CDCl3): δ 191.3, 139.2, 136.7, 128.7, 128.3, 51.5, 41.9, 36.3, 29.9; Anal. Calcd. for
C17H19ClOS: C, 66.54; H, 6.24; S, 10.45. Found: C, 66.75; H, 6.09; S, 10.59.
(3s): White crystals; mp (EtOH):123–125◦C; 1H NMR (400 MHz, CDCl3): δ 7.86 (d, J = 6.8 Hz,
2H), 7.28 (d, J = 7.2 Hz, 2H), 2.96 (m,1H), 2.28 (s, 6H), 2.11 (s,3H), 1.84 (d, J = 12.2 Hz, 3H),
1.76 (d, J = 12.2 Hz, 3H), 1.27 (d, J = 6.4 Hz, 6H) 13C NMR (100 MHz, CDCl3): δ 192.2, 154.3,
136.2, 127.1, 126.5, 50.9, 36.4, 36.1, 34.2, 29.9, 23.7; Anal. Calcd. for C20H26OS: C, 76.38; H,
8.33; S, 10.20. Found: C, 76.56; H, 8.24; S, 10.34.
1
(3t): White crystals; mp (EtOH): 123–125◦C; H NMR (400 MHz, CDCl3): δ 7.61 (d,d, J =
8.4 Hz, J = 2.0 Hz, 1H), 7.43 (d, J = 2.0 Hz, 1H), 6.86 (d, J = 8.4 Hz, 1H), 3.94 (s, 3H), 3.93
(s, 3H), 2.27 (d, J = 1.6 Hz, 6H), 2.10 (s, 3H), 1.82(d, J = 12.2 Hz, 3H), 1.75 (d, J = 12.2 Hz,
3H); 13C NMR (100 MHz, CDCl3): δ 191.4, 153.0, 148.7, 131.3, 121.3, 110.0, 109.1, 56.0, 55.9,

Journal of Sulfur Chemistry 293
51.0, 42.1, 36.4, 29.9; Anal. Calcd. for C19H24O3S: C, 68.64; H, 7.28; S, 9.64. Found: C, 68.76;
H, 7.21; S, 9.55.
Acknowledgement
We are grateful to University of Isfahan research council for financial support of this work.
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