One-pot synthesis and methylation of 3-[2-(1 H -benzimidazol-2-yl-sulfanyl) -acetyl]-chromen-2-ones

Article abstract of DOI:10.1080/10426507.2011.608321

3-(2-Bromoacetyl)coumarins (I), when treated with 2-mercatobenzimidazole (II) in acetone containing K₂CO₃ (mild base) and tetrabutylammonium bromide (TBAB) as a phase transfer catalyst, at room temperature yielded the title compound 3-[2-(1H-benzimidazole-2-yl-sufanyl)- acetyl]-chromen-2-one (III) in a one-pot synthesis. Alternatively, III could also be prepared by treating dithiocarbonic acid O-ethyl ester, S-[2-oxo-2-(2-oxo-2H-chromen3-yl)-ethyl] ester (V), with o-phenylenediamine (VI). The methylation of the title compound III was performed with dimethyl sulfate (DMS), in acetonitrile containing TBAB and K₂CO₃ at room temperature, resulting in 3-[2-(N-methyl-benzimidazol-2-yl-sulfanyl)]- acetyl-chromen-2-ones (VII). Alternatively, methylation of III could also be performed with DMS in acetonitrile containing K₂CO₃ as base and clay as surface catalyst. All the compounds were synthesized in good yields and their structures were confirmed by spectral and analytical data. [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: ¹H NMR of IIIB, VB and VIIB] Copyright Taylor and Francis Group, LLC.

Full text of DOI:10.1080/10426507.2011.608321

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One-Pot Synthesis and Methylation of
3-[2-(1H-Benzimidazol-2-yl-Sulfanyl)-
Acetyl]-Chromen-2-Ones
S. Tasqeeruddin a & P. K. Dubey a
a Department of Chemistry, College of Engineering, Jawaharlal
Nehru Technological University Hyderabad, Hyderabad, Andhra
Pradesh, India
Version of record first published: 06 Dec 2011.
To cite this article: S. Tasqeeruddin & P. K. Dubey (2012): One-Pot Synthesis and Methylation of 3-
[2-(1H-Benzimidazol-2-yl-Sulfanyl)-Acetyl]-Chromen-2-Ones, Phosphorus, Sulfur, and Silicon and the
Related Elements, 187:1, 128-134
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Phosphorus, Sulfur, and Silicon, 187:128–134, 2012
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2011.608321
ONE-POT SYNTHESIS AND METHYLATION OF
3-[2-(1H-BENZIMIDAZOL-2-YL-SULFANYL)-ACETYL]-
CHROMEN-2-ONES
S. Tasqeeruddin and P. K. Dubey
Department of Chemistry, College of Engineering, Jawaharlal Nehru
Technological University Hyderabad, Hyderabad, Andhra Pradesh, India
GRAPHICAL ABSTRACT
C2H5O
SK
R2
R1
O
O
C
S
(IV)
Acetone/TBAB
K2CO3/r.t.
Br
C2H5OH
∆
O
(1)
H
N
R2
O
O
S
(II)
HS
R1
S
C
N
OC2H5
(V)
O
H2N
R2
R1
O
O
O
H
N
H2N
S
(VI)
N
(III)
CH3CN/DMS/K2CO3
Mont-KSF-Clay/r.t.
CH3CN/DMS/r.t.
K2CO3/TBAB
R2
R1
O
O
O
CH3
N
S
N
(VII)
Abstract 3-(2-Bromoacetyl)coumarins (I), when treated with 2-mercatobenzimidazole (II) in
acetone containing K2CO3 (mild base) and tetrabutylammonium bromide (TBAB) as a phase
transfer catalyst, at room temperature yielded the title compound 3-[2-(1H-benzimidazole-2-
yl-sufanyl)-acetyl]-chromen-2-one (III) in a one-pot synthesis. Alternatively, III could also be
prepared by treating dithiocarbonic acid O-ethyl ester, S-[2-oxo-2-(2-oxo-2H-chromen3-yl)-
ethyl] ester (V), with o-phenylenediamine (VI). The methylation of the title compound III was
performed with dimethyl sulfate (DMS), in acetonitrile containing TBAB and K2CO3 at room
temperature, resulting in 3-[2-(N-methyl-benzimidazol-2-yl-sulfanyl)]-acetyl-chromen-2-ones
(VII). Alternatively, methylation of III could also be performed with DMS in acetonitrile
containing K2CO3 as base and clay as surface catalyst. All the compounds were synthesized
in good yields and their structures were confirmed by spectral and analytical data.
Received 19 January 2011; accepted 11 July 2011.
The authors are thankful to the authorities of Jawaharlal Nehru Technological University Hyderabad for
providing laboratory facilities.
Address correspondence to S. Tasqeeruddin, Department of Chemistry, College of Engineering, Jawaharlal
Nehru Technological University Hyderabad, Kukatpally, Hyderabad 500085, Andhra Pradesh, India. E-mail:
tasqeeruddin@gmail.com
128

3-[2-(1H-BENZIMIDAZOL-2-YL-SULFANYL)-ACETYL]-CHROMEN-2-ONES
129
[Supplemental materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental
resource: 1H NMR of IIIB, VB and VIIB]
Keywords 3-(2-Bromoacetyl)coumarins; dithiocarbonic acid O-ethyl ester S-[2-oxo-2-(2-oxo-
2H-chromen3-yl)-ethyl] ester; DMS; clay
INTRODUCTION
Literature reports revealed that coumarin derivatives constitute an important class
of heterocyclic compounds with anticoagulant (e.g., warfarin, acenocoumarol),1,2 rodenti-
cide (e.g., brodifacoum, bromadiolone),3 insecticide (e.g., coumaphos),4 and antibacterial
(e.g., novobiocin, clorobiocin)5,6 properties. They also possess important biological activ-
ities like antitumor,7 antifungal,8 antimycobacterial,9 and anti-inflammatory10 properties.
However, there are other coumarin compounds such as N-acetyl-N-allylamino-4-thiazolyl-
coumarins,11 N-chloroacetamido derivatives,12 and N-benzoyl derivatives, which displayed
significant analgesic and anti-inflammatory activity.13 In view of these wide ranges of
pharmacological activities of coumarin derivatives, it was thought of interest to synthesize
potent coumarin derivatives, which may possess useful biological properties.
RESULTS AND DISCUSSION
The reaction of 3-(2-bromoacetyl)coumarin,14 (Ia, i.e., I, R1 = R2 = H), with
2-mercaptobenzimidazole15 (II), in acetone containing tetrabutylammonium bromide
(TBAB) as phase transfer catalyst and K2CO3 as a base at room temperature, gave a
product, which has been characterized as 3-[2-(1H-benzimidazole-2-yl-sulfanyl)-acetyl]-
chromen-2-ones (IIIa, i.e., III, R1 = R2 = H), on the basis of its spectral and analytical
data.
IIIa (i.e., III, R1 = R2 = H) could also be synthesized by an alternative method.
Thus, reaction of Ia (i.e., I, R1 = R2 = H) with potassium ethoxydithiocarbamate (IV)
gave dithiocarbonic acid O-ethyl ester S-[2-oxo-2-(2-oxo-2H-chromen3-yl)-ethyl] ester
(Va, i.e., V, R1 = R2 = H), which when treated with o-phenylenediamine (VI), in ethanol
under reflux for 2–3 h, followed by a workup, afforded a white crystalline solid identical
with IIIa (i.e., III, R1 = R2 = H), in all respects (mp, mmp., and co-TLC) (Scheme 1).
The above reaction of Ia (i.e., I, R1 = R2 = H) with II was found to be a general
one and the other compounds, namely, 3-[2-(1H-benzimidazol-2-yl-sulfanyl)-acetyl]-6-
hydroxy-[-chromen-2-one] (IIIb, i.e., III, R1 = OH, R2 = H), 3-[2-(1H-benzimidazol-2-yl-
sulfanyl)-acetyl]-6-methoxy-[-chromen-2-one] (IIIc, i.e., III, R1 = OCH3, R2 = H), and 3-
[2-(1H-benzimidazol-2-yl-sulfanyl)-acetyl]-6,7-dichloro-[-chromen-2-one] (IIId, i.e., III,
R1 = R2 = Cl), have been synthesized by extending it. All the compounds have been
characterized by spectral and analytical data (for details please see experimental data).
Potassium ethoxydithiocarbamate (IV) required in the above reaction was prepared
by refluxing KOH in ethanol followed by addition of carbon disulfide in ice-cold condition16
to the preliminary solution. When Ia (i.e., I, R1 = R2 = H) was treated with IV in ethanol
under reflux condition for 1–2 h, dithiocarbonic acid O-ethyl ester S-[2-oxo-2-(2-oxo-
2H-chromen-3-yl)-ethyl] ester (Va, i.e., V, R1 = R2 = H) was obtained, which has been
characterized by spectral and analytical data.

130
S. TASQEERUDDIN AND P. K. DUBEY
S
R2
R1
O
O
O
C
(IV)
OC2H5
Acetone/TBAB
RT/K2CO3
KS
Br
C2H5OH
∆
(I)
H
N
R2
O
O
S
HS
(II)
R1
S
C
N
OC2H5
(V)
O
H2N
H
N
R2
O
O
H2N
S
R1
(VI)
N
O
(III)
CH3CN/DMS
CH3CN/DMS/K2CO3
K2CO3/TBAB/RT
Mont-KSF-Clay/RT
CH3
N
R2
R1
O
O
O
S
N
(VII)
R1= H, OH, OCH3, Cl
R2=Cl
Scheme 1
The other compounds such as dithiocarbonic acid O-ethyl ester, S-[2-(6-hydroxy-2-
oxo-2H-chromen-3-yl)-2-oxo-ethyl] ester (Vb, i.e., V, R1 = OH, R2 = H), dithiocarbonic
acid O-ethyl ester, S-[2-(6-methoxy-2-oxo-2H-chromen-3-yl)-2-oxo-ethyl] ester (Vc, i.e.,
V, R1 = OCH3, R2 = H), and dithiocarbonic acid S-[2-(6,7-dichloro-2-oxo-2H-chromen-
3-yl)-2-oxo-ethyl] ester O-ethyl ester (Vd, i.e., V, R1 = R2 = Cl) have been prepared by
extending the above reaction. All the compounds have been characterized by spectral and
analytical data. The yields, melting points and spectral data, are given in the Experimental
Section.
Treatment of IIIa (i.e., III, R1 = R2 = H) with dimethylsulfate (DMS), in CH3CN con-
taining K2CO3 as a base and TBAB as PTC, afforded a pure crystalline solid. The compound
has been assigned as 3-[2-(N-methyl-benzimidazol-2-yl-sulfanyl)]-acetyl-chromen-2-one
(VIIa, i.e., VII, R1 = R2 = H), on the basis of spectral and analytical data.
VIIa (i.e., VII, R1 = R2 = H) could also be prepared by treating the suspension of
IIIa (i.e., III, R1 = R2 = H) in CH3CN, with DMS and base K2CO3, in the presence of
clay (montmorillonite-KSF), identical in all respects (mp, mmp, and co-TLC result).
By adopting the same procedure, other compounds, namely, 6-hydroxy-3-[2-(1-
methyl-1H-benzimidazol-2-yl-sulfanyl)-acetyl-chromen-2-one (VIIb, i.e., VII, R1 = OH,
R2 = H), 6-methoxy-3-[2-(1-methyl-1H-benzimidazol-2-yl-sulfanyl)-acetyl-chromen-
2-one, (VIIc, i.e., VII, R1 = OCH3, R2 = H), and 6,7-dichloro-3-[2-(1-methyl-1H-
benzimidazol-2-yl-sulfanyl)-acetyl-chromen-2-one (VIId, i.e., VII, R1 = R2 = Cl), have

3-[2-(1H-BENZIMIDAZOL-2-YL-SULFANYL)-ACETYL]-CHROMEN-2-ONES
131
been synthesized. All the compounds have been characterized by spectral and analytical
data.
It may be mentioned here that the reactions catalyzed by clays have received great
attention in recent years.17–20 The salient features of the reactions catalyzed by clay sup-
ported reagents are that the clay catalyst can be recovered after the completion of reaction
by simple filtration.21 The recovered catalyst is washed thoroughly with diethyl ether and
dried at 140 ◦C for 1 h under vacuum. The recovered catalyst, in the present work, showed
consistent activity for five cycles, and then, the activity slowly begins to decrease.
EXPERIMENTAL SECTION
General Conditions
Melting points are uncorrected and were determined in open capillary tubes in sulfuric
acid bath. TLC was performed on silica gel-G and spotting was done using iodine or UV-
1
light. IR spectra were recorded with Perkin-Elmer 1000 instrument in KBr phase. H
NMR was recorded on VARIAN 400 MHz instrument and Mass spectra were recorded on
Agilent-LC-MS instrument.
Preparation of 3-[2-(1H-Benzimidazole-2-yl-Sulfanyl)-Acetyl]-
Chromen-2-Ones (III) (General Procedure)
A mixture of 2-mercaptobenzimidazole (II) (0.75 g, 0.005 mol) in dry acetone
(50 mL), K2CO3 (2.76 g, 0.01 mol), and TBAB (0.05 g) was stirred at room temperature
for 0.5 h. To this mixture, 3-(2-bromoacetyl)coumarins (I) (1.19 g, 0.005 mol) was added
and was continued stirring further for 2–3 h. The completion of the reaction was monitored
by TLC analysis. After completion of reaction, the mixture was poured in ice-cold water
and neutralized with NaHCO3. The solid obtained was filtered and dried. It was recrys-
tallized from dimethyl formamide (DMF)/methanol (1:1 ratio), yielding a pure crystalline
solid.
IIIa: White crystalline solid; Yield 1.4 g (92%); mp 178 ◦C–79 ◦C; IR (KBr) 3423
cm−1 (medium, broad assignable to –NH–), 1720 cm−1 (strong, sharp, due to lactone C O
1
group) 1640 cm−1 (strong, sharp, assignable to C O of COCH2–). H NMR spectrum
(DMSO-d6/TMS), showed signals at δ 5.56 (s, 2H, –CH2–), 7.34–8.88 (complex, m, 9H,
aryl protons, J = 3–7 Hz) 12.68 (s, br, 1H, –NH–). 13C NMR (DMSO-d6/TMS) δ 65, 116,
119, 121, 125, 127, 129, 134, 145, 151, 168, 172. IMS (CI, M.++1) m/z 337 (base peak).
Elem. Anal: Found. C 64.27%, H 3.60%, N 8.33%; C18H12N2O3S requires C 64.25%, H
3.58%, N 9.15%.
IIIb: White crystalline solid; Yield 1.3 g (88%); mp 263 ◦C–64 ◦C; IR (KBr): 3450
cm−1 (medium, broad, –NH– stretching); 1740 cm−1 (strong, sharp, C O of coumarin
ring); 1628 cm−1 (strong, sharp, C O of COCH2–). 1H NMR (DMSO-d6/TMS): δ 5.66 (s,
2H, –CH2–), 7.14–8.88 (complex, m, 8H, aryl protons) 11.42 (s, 1H, D2O Exchangeable
–OH), 12.20 (s, 1H, –NH–); MS m/z = 353 (M.+ + 1). Elem. Anal: Found. C 61.90%, H
4.35%, N 7.31%, S 8.68%; C18H12N2O4S requires C 61.94%, H 4.38%, N 7.32%, S 8.71%.
IIIc: White crystalline solid; Yield 1.34 g (84%); mp 243 ◦C–245 ◦C; IR (KBr): 3455
cm−1 (medium, broad,–NH– stretching), 1730 cm−1 (strong, sharp, C O of coumarin ring),
1660 cm−1 (strong, sharp, C O of COCH2–); 1H NMR (DMSO-d6/TMS) signals at δ 4.34
(s, 3H, –OCH3–), 5.68 (s, 2H, –CH2–), 7.12–8.88 (complex, m, 8H, aryl protons) δ 12.20

132
S. TASQEERUDDIN AND P. K. DUBEY
(s, 1H, –NH–); MS m/z = 367 (M.+ + 1). Element. Anal: Found. C 62.79%, H 4.71%, N
17.31%, S 8.35%; C19H14N2O4S requires C 62.81%, H 4.73%, N 7.31%, S 8.38%.
IIId: White crystalline solid; Yield 1.17g (80%); mp 254 ◦C–255 ◦C; IR (KBr): 3460
cm−1 (medium, broad, –NH– stretching), 1741 cm−1 (strong, sharp, C O of coumarin
1
ring), 1660 cm−1 (strong, sharp, C O of COCH2–); H NMR (DMSO-d6/TMS) signals
at δ 5.88(s, 2H, –CH2–), 7.22–8.86 (complex, m, 7H, aryl protons) and at δ 12.40 (s, 1H,
–NH–), MS m/z = 405 (M.+ + 1). Elem. Anal: Found. C 54.15%, H 3.33%, N 6.63%, S
7.59%; C18H10Cl2N2O3S requires C 54.17%, H 3.35%, N 6.65%, S 7.61%.
Preparation of Dithiocarbonic Acid O-Ethyl Ester
S-[2-Oxo-2-(2-Oxo-2H-Chromen-3-yl)-Ethyl] Ester (V) (General Procedure)
A mixture of 3-(2-bromoacetyl)coumarin (I) (0.01 mol), potassium ethoxydithio-
carbamate (IV) (1.60 g, 0.01 mol), and ethanol (30 mL) was refluxed for 1 h. Then, the
reaction mixture was cooled to room temperature and the separated KBr salt was filtered
and washed with ethanol (10 mL). The filtrate was distilled off and the residue diluted with
water. The separated solid was filtered, washed with water, and dried to give V.
Va: Crystalline solid; Yield 1.35 g (88%); mp 154 ◦C–56 ◦C; IR (KBr) 1735 cm−1
(strong, sharp, assignable to lactone C O), 1678 cm−1 (strong, sharp due to C O of
1
COCH2–). H NMR (DMSO-d6/TMS), spectrum showed signal at δ 1.24 (t, 3H, –CH3),
5.24 (q, 2H, –CH2-), 6.66 (s, 2H, –CH2–), 7.38–8.88 (complex, m, 5H, aryl protons, J =
3–7.5 Hz). Its 13C spectrum (DMSO-d6/TMS) showed signals at ca δ 18, 62, 66, 116, 119,
121, 127, 129, 134, 151, 160, 166, and 177. Its MS (CI) (M.+ + 1) m/z 309 (base peak).
Elem. Anal: Found. C 54.50%, H 3.88%, S 20.78%; C14H12O4S2 requires C 54.53%, H
3.91%, S 20.80%.
Vb: Crystalline solid; Yield 1.24 g (82%); mp 188 ◦C–90 ◦C; IR (KBr): 1745 cm−1
(strong, sharp, C O of coumarin ring), 1681 cm−1 (strong, sharp, C O of COCH2–). 1H
NMR (DMSO-d6/TMS) signal at δ 1.31 (t, 3H, –CH3), 4.88 (q, 2H, –CH2–), 5.21 (s, 2H,
–CH2–), 7.31–8.98 (complex, m, 5H, aryl protons). 10.81 (s, 1H, OH). MS m/z = 325 (M.+
+ 1). Elem. Anal: Found. C 51.81%, H 3.70%, S 19.74%; C14H12O5S2 requires C 51.84%,
H 3.73%, S 19.78%.
Vc: Crystalline solid; Yield 1.15 g (80%); mp 219 ◦C–21 ◦C; IR (KBr): 1748 cm−1
(strong, sharp, C O of coumarin ring), 1677 cm−1 (strong, sharp, C O of COCH2–). 1H
NMR (DMSO-d6/TMS), spectrum showed signal at δ 1.53 (t, 3H, –CH3), 4.29 (s, 3H,
–OCH3–), 5.13 (q, 2H, –CH2–), 5.40 (s, 2H, –CH2–), 7.11–8.88 (complex, m, 5H, aryl
protons); MS m/z = 338 (M.+ + 1). Elem. Anal: Found. C 53.21%, H 4.15%, S 18.93%;
C15H14O5S2 requires C 53.24%, H 4.17%, S 18.95%.
Vd: Crystalline solid; Yield 1.23 g (80%); mp 227 ◦C–29 ◦C; IR (KBr) 1751 cm−1
(strong, sharp, C O of coumarin ring), 1672 cm−1 (strong, sharp, C O of COCH2–). 1H
NMR (DMSO-d6/TMS), signal at δ 1.59 (t, 3H, –CH3), 4.83 (q, 2H, –CH2–), 5.12 (s, 2H,
–CH2–), 7.13–8.89 (complex, m, 3H, aryl protons); MS m/z = 377 (M.+ + 1). Elem. Anal:
Found. C 44.55%, H 2.65%, S 16.98%; C14H10Cl2O4S2 requires C 44.55%, H 2.67%, S
17.00%.
Alternative Method for the Synthesis of III
Dithiocarbonic acid O-ethyl ester, S-[2-oxo-2-(2-oxo-2H-chromen-3-yl)-ethyl] ester
(V) (0.01 mol), was refluxed with o-phenylenediamine (VI) (0.01 mol), for 8–10 h, in

3-[2-(1H-BENZIMIDAZOL-2-YL-SULFANYL)-ACETYL]-CHROMEN-2-ONES
133
C2H5OH (50 mL). The completion of the reaction was monitored by TLC analysis. At the
end, the reaction mixture was poured in ice-cold water, neutralized with conc. HCl and pH
was adjusted to neutral with aq. NH3. The separated solid was filtered, washed with water,
and dried to obtain III.
Preparation of 3-[2-(N-Methyl-Benzimidazol-2-yl-Sulfanyl)]-
Acetyl-Chromen-2-One (VII) from III (General Procedure)
A mixture of 3-[2-(1H-benzimidazole-2-yl-sulfanyl)-acetyl]-chromen-2-ones (III)
(0.01 mol), K2CO3 (1.63 g, 0.012 mol), TBAB (0.2 g), dimethyl sulfate (1.0mL, 0.01
mol), and acetonitrile (25 mL) was stirred at room temperature for 3 h. On completion of
the reaction, the mixture was filtered and the insoluble material washed with CH3CN (2 ×
5 mL); the CH3CN filtrate was evaporated to dryness and the residue treated with chloroform
(25 mL). The chloroform layer was washed with water (3 × 30 mL) and evaporated to
dryness, to give crude VII. It was recrystallized from methanol-chloroform to obtain pure
VII.
◦
◦
VIIa. Yellow solid; Yield 1.17 g (90%); mp 219 C–21 C; IR (KBr) 3423 cm−1
(medium, broad, NH group); 1748 cm−1 (strong, sharp assignable to lactone C O group)
1693 cm−1 (strong, sharp due to C O of COCH2– group). 1H NMR (DMSO-d6/TMS) δ
5.28 (s, 3H, N–CH3), 5.30 (s, 2H, –CH2–), 6.98–9.01 (complex, m, 9H, aryl protons, J =
2.5–8 Hz). MS (M.+ + 1) m/z 351 (base peak) corresponding to a molecular mass of 350.
Elem. Anal: Found. C 65.64%, H 4.93%, N 7.62%, S 8.71%; C20H13N3O3S requires C
65.66%, 4.95%, N 7.64%, S 8.74%.
VIIb. Yellow solid; Yield 1.1 g (84%); mp 201 C–03 C; IR (KBr): 1740 cm−1
(strong, sharp, C O of coumarin ring), 1640 cm−1 (strong, sharp, C O of COCH2-); 1H
NMR (DMSO-d6/TMS), δ 6.04 (s, 3H, N–CH3), 6.28 (s, 2H, –CH2–), 7.12–8.88 (complex,
m, 8H, aryl protons), 11.22 (s, 1H, –OH); MS m/z = 367 (M.+ + 1). Elem. Anal: Found.
C 62.80%, H 4.71%, N 7.31%, S 8.34%; C19H14N2O4S requires C 62.81%, H 4.74%, N
7.33%, S 8.38%.
◦
◦
◦
◦
VIIc. Yellow solid; Yield 1.0 g (80%); mp 211 C–13 C; IR (KBr) 1738 cm−1
(strong, sharp, C O of coumarin ring), 1648 cm−1 (strong, sharp, C O of COCH2); H
1
NMR (DMSO-d6/TMS) δ 2.22 (s, 3H, O–CH3), 5.68 (s, 3H, N–CH3), 5.72 (s, 2H, –CH2–),
7.27–8.89 (complex, m, 8H, aryl protons); MS m/z = 381 (M.+ + 1). Elem. Anal: Found.
C 63.60%, H 5.05%, N 7.05%, S 8.05%; C20H16N2O4S requires C 63.63%, H 5.08%, N
7.07%, S 8.07%.
◦
◦
VIId. Yellow solid; Yield 1.0 g (77%); mp 231 C–33 C; IR (KBr) 1742 cm−1
(strong, sharp, C O of coumarin ring), 1652 cm−1 (strong, sharp, C O of COCH2); H
1
NMR (DMSO-d6/TMS) δ 5.74 (s, 3H, N–CH3), 5.81 (s, 2H, –CH2–), 7.21–8.88 (complex,
m, 7H, aryl protons); MS m/z = 419 (M.+ + 1). Elem. Anal: Found. C 55.14%, H 3.04%,
N 6.63%, S 7.35%; C19H12N2O4S requires C 55.18%, H 3.08%, N 6.66%, S 7.37%.
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