Synthesis of a new class of Sulfone-linked 3-([1,2,3]-thiadazol-4-yl)- chromen-2-ones

Article abstract of DOI:10.1080/10426500902797137

A new class of 3-[5-(phenylsulfonyl)1,2,3-thiadizol-4-yl)-2H-chromen-2-ones (5) has been prepared from 3-(2-(phenylsulfonyl)-2H-chromen-2-ones (4).

Full text of DOI:10.1080/10426500902797137

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Phosphorus, Sulfur, and Silicon and the
Related Elements
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Synthesis of a New Class of Sulfone-
Linked 3-([1,2,3]-Thiadazol-4-yl)-
chromen-2-ones
Nalajam Guravaiah a & Vedula Rajeswar Rao a
a Department of Chemistry, National Institute of Technology,
Warangal, India
Version of record first published: 03 Feb 2010.
To cite this article: Nalajam Guravaiah & Vedula Rajeswar Rao (2010): Synthesis of a New Class of
Sulfone-Linked 3-([1,2,3]-Thiadazol-4-yl)-chromen-2-ones, Phosphorus, Sulfur, and Silicon and the
Related Elements, 185:2, 361-367
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Phosphorus, Sulfur, and Silicon, 185:361–367, 2010
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500902797137
SYNTHESIS OF A NEW CLASS OF SULFONE-LINKED
3-([1,2,3]-THIADIAZOL-4-YL)-CHROMEN-2-ONES
Nalajam Guravaiah and Vedula Rajeswar Rao
Department of Chemistry, National Institute of Technology, Warangal, India
A new class of 3-[5-(phenylsulfonyl)1,2,3-thiadizol-4-yl)-2H-chromen-2-ones (5) has been
prepared from 3-(2-(phenylsulfonyl)-2H-chromen-2-ones (4).
Keywords β-Keto sulfones; 3-2(bromo acetyl) coumarin; hydrazones; thiadiazole; thionyl
chloride
INTRODUCTION
The development of simple, facile, and efficient methods for the synthesis of five-
membered heterocycles is one of the major challenges in organic synthesis. Among five-
membered heterocycles, thiadazoles, oxadiazoles, and trizoles have gained importance
because of their intrinsic biological activities, and because they constitute the structural
features of many bioactive compounds. In fact, some of them have also emerged as potential
drugs.1–5 The molecules having a substituted thiadiazole act as an intermediate for the
therapeutically useful antibiotic cefazolin.6
The prominence of 2H-chromen-2-ones in natural products and biologically ac-
tive molecules7–16 has promoted considerable efforts toward their synthesis. As a “privi-
leged” scaffold, 2H-chromen-2-ones show interesting biological properties, especially for
their anti-HIV and antibiotic activities.17–25 For example, novobiocin is a 2H-chromen-2-
one–derived antibiotic used as a competitive inhibitor of the bacterial ATP binding gyrase
B subunit, blocking the negative supercoiling of relaxed DNA.17,20 Lamellarin is utilized
as a selective inhibitor of HIV-I integrase.25 The discovery of promising lead antivirus
compounds and their moderate activity warranted the development of efficient and rapid
synthesis and evaluation of analogous structures in the search for better inhibitors. Thus, we
initiated a program to develop efficient methods for the synthesis of diversified coumarin
molecules, with the hope of finding more active hits or leads for our particular biological
assays.
Received 18 August 2008; accepted 4 February 2009.
Financial support from CSIR, New Delhi, India, for the sanction of the project (No.01 (2062) 06/EMR-II)
is gratefully acknowledged. We also give thanks to the Head, Analytical Division, IICT, Hyderabad, India, for
analytical and spectral data.
Address correspondence to V. Rajeswar Rao, Department of Chemistry, National Institute of Technology,
Warangal 506 004, A.P., India. E-mail: vrajesw@yahoo.com and nalajamorg@gmail.com
361

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N. GURAVAIAH AND V. RAJESWAR RAO
Our interest is in the development of novel heterocyclic systems at the three position
of 2H-chromen-2-ones. In continuation of our earlier work on the synthesis of heterocyclic
systems derived from coumarin, in this article we report the synthesis of a new class of 5-
phenylsulfonyl-2H-coumarinyl 1,2,3-thiadiazoles exploiting ketomethylene functionality
in 3-(2-benzenesulfonylacetyl)-chromen-2-ones.
RESULTS AND DISCUSSION
The synthetic method involves the condensation of 3-(2-bromoacetyl) coumarins
prepared from the appropriate 3-acetylcoumarins, with sodiumaryl sulfinates to obtain
3-[2-(phenylsulfonyl)acetyl-2H-chromen-2-ones (3).26 These, in reaction with semicar-
bazide hydrochloride, afforded the expected semicabazones (4). Upon cyclization with
thionylchloride, thiadiazoles (5) were furnished.
The IR spectra of 4a displayed bands in the region 3284–3469 (CONH2 and NHCO)
and 1713 cm−1 (C O of lactone), 1446 cm−1 (C N), apart from the bands at 1314 and
1147 cm−1 (SO2). The 1H NMR spectrum of 4a displayed a characteristic singlet for the
methylene proton at δ 4.96. The C4 proton of coumarin appeared as a singlet as 7.8. The
NH proton was observed at δ 9.9. In the mass spectrum of 4a, a molecular ion was recorded
at m/z 385. The IR spectra of 5a displayed bands in the region 1331 and 1152 cm−1 (SO2),
1446 (N N) cm−1. The 1H NMR spectrum of 5a displayed a singlet 8.14 (C4 of coumarin),
and the remaining protons were observed in the expected region. In the mass spectrum of
5a, the molecular ion was recorded at m/z 370.The newly synthesized compounds have
been characterized by their analytical and spectral data (Scheme 1).
EXPERIMENTAL
All the reagents and solvents were pure, were purchased from commercial sources,
and were used with out further purification unless otherwise stated. 3-(2-Bromoacetyl)
coumarins27,28 were prepared by the procedure in the literature. Melting points were de-
termined in open capillaries with a Cintex melting point apparatus, Mumbai, India, and
were uncorrected. CHNS analysis was done by a Carlo Erba EA 1108 automatic elemental
analyzer. The purity of the compounds was checked by TLC plates (E. Merck, Mumbai,
India), and IR spectra (KBr) were recorded on a BrukerWM-4(X) spectrometer (577 model).
1H NMR spectra were recorded on a Bruker WM-300 spectrometer in δ ppm using TMS
as internal standard. The NH and NH2 protons were exchanged with D2O. Mass spectra
(EI-MS) were determined on a Perkin Elmer (SCIEX API-2000, ESI) at 12.5 eV.
(1Z)-1-(1-(2-Oxo-2H-chromen-3-yl)-2-(phenylsulfonyl)ethylidene)semicar
bazide (4)
A mixture of 3-(2-(phenylsulfonyl)acetyl)-2H-chromen-2-one (1 mmol), semicar-
bazide hydrochloride (1.2 mmol), and sodium acetate (1 mmol) in methanol was refluxed
for 4–6 h on a steam bath and cooled. The reaction mixture was concentrated, cooled, and
poured on to crushed ice. The solid was collected by filtration, dried, and recrystallized
from ethanol. All other compounds were prepared similarly.
(1Z)-1-(1-(2-Oxo-2H-chromen-3-yl)-2-(phenylsulfonyl)ethylidene)semicar
bazide (4a). Yield 96%, mp 208–210◦C. IR (KBr, γ max cm−1): 1147, 1314 (SO2), 1446

SULFONE-LINKED 3-([1,2,3]-THIADIAZOL-4-YL)-CHROMEN-2-ONES
363
R1
SO2Na
O
O
O
R1
i
+
O
O
O
R2
Br
O
S
R
R2
O
1
2
3
R1
R1
O
O
O
O
iii
N
S
O
ii
R
N
N
R
NH
3
O
O
NH2
S
S
O
O
4
5
R2
R2
(i) EtOH/ heat
g) R= R1=H R2= CH3
a) R= R1= R2= H
(ii) NH2NHCONH2 /AcONa /MeOH
(iii) SOCl2 , heat
h) R= Br R1=H R2= CH3
i) R= R1= Br R2= CH3
j) R= Cl R1=H R2= CH3
k) R= R1= Cl R2= CH3
l) 7,8 benzo R2= CH3
b) R= Br R1= R2= H
c) R= R1= Br R2= H
d) R= Cl R1= R2= H
e) R= R1= Cl R2= H
f) 7,8 benzo R2= H
Scheme 1
(C N), 1699 (NHCO), 1713 (C O of lactone), 3284 (CONH2), 3469 (NHCO), 1H NMR
(CDCl3+DMSO-d6, δ ppm): 4.96 (s, 2H CH2), 7.13–7.39 (m, 9H, Ar H and NH2),
7.69–7.75 (m, 3H, Ar H and C4 of coumarin), 9.89 (br, s, NH). EI-MS 386 (M+H)+.
Anal. Calcd. for C18H15N3O5S: C, 56.10; H, 3.92; N, 10.90. Found: C, 56.00; H, 3.90; N,
10.84%.
(1Z)-1-(1-(6-Bromo-2-oxo-2H-chromen-3-yl)-2-(phenylsulfonyl)ethylidene)
semicarbazide (4b). Yield 92%, mp 224–226◦C. IR (KBr, γ max cm−1): 1148, 1318
(SO2), 1447 (C N), 1692 (NHCO), 1716 (C O of lactone), 3200 (CONH2), 3333
1
(NHCO), H NMR (CDCl3+DMSO-d6, δ ppm): 4.60 (s, 2H CH2), 7.0–7.40 (m, 7H,
Ar H and NH2), 7.50–7.70 (m, 3H, Ar H), 8.30 (s, 1H, C4 of coumarin), 9.30 (br, s, NH)
Anal. Calcd. for C18H14BrN3O5S: C, 46.56; H, 3.04; N, 9.05. Found: C, 46.60; H, 3.00;
N, 9.10%.
(1Z)-1-(1-(6,8-Dibromo-2-oxo-2H-chromen-3-yl)-2-(phenylsulfonyl)ethyli
dene)semicarbazide (4c). Yield 89%, mp 232–234◦C. IR (KBr, γ max cm−1): 1144,
1321 (SO2), 1446 (C N), 1688 (NHCO), 1726 (C O of lactone), 3195 (CONH2), 3454
(NHCO), 1H NMR (CDCl3+DMSO-d6, δ ppm): 4.80 (s, 2H CH2), 7.0–7.60 (m, 9H, Ar H
and NH2), 8.0 (s, 1H, C4 of coumarin), 8.70 (br, s, NH). Anal. Calcd. for C18H13Br2N3O5S:
C, 39.80; H, 2.41; N, 7.74. Found: C, 39.83; H, 2.38; N, 7.71%.

364
N. GURAVAIAH AND V. RAJESWAR RAO
(1Z)-1-(1-(6-Chloro-2-oxo-2H-chromen-3-yl)-2-(phenylsulfonyl)ethylidene)
semicarbazide (4d). Yield 93%, mp 226–228◦C. IR (KBr, γ max cm−1): 1141,
1323 (SO2), 1446 (C N), 1702 (NHCO), 1725 (C O of lactone), 3207 (CONH2),
1
3452(NHCO), H NMR (CDCl3+DMSO-d6, δ ppm): 4.50 (s, 2H CH2), 7.71–8.20 (m,
11H, Ar H and NH2), 8.60 (s, 1H, C4 of coumarin), 9.22 (br, s, NH). Anal. Calcd. for
C18H14ClN3O5S: C, 51.49; H, 3.36; N, 10.01. Found: C, 51.52; H, 3.33; N, 10.00%.
(1Z)-1-(1-(6,8-Dichloro-2-oxo-2H-chromen-3-yl)-2-(phenylsulfonyl)ethyli
dene)semicarbazide (4e). Yield 90%, mp 204–206◦C. IR (KBr, γ max cm−1): 1142,
1323 (SO2), 1446 (C N), 1702 (NHCO), 1725 (C O of lactone), 3205 (CONH2), 3452
1
(NHCO), H NMR (CDCl3+DMSO-d6, δ ppm): 4.65 (s, 2H CH2), 7.20–7.40 (m, 2H,
Ar H and NH2), 7.61–7.73 (m, 7H, Ar H), 8.40 (s, 1H, C4 of coumarin), 9.12 (br, s, NH)
Anal. Calcd. for C18H13Cl2N3O5S: C, 47.59; H, 2.88; N,9.25. Found: C, 47.54; H, 2.83;
N, 9.28%.
(1Z)-1-(1-(2-Oxo-2H-benzo[h]chromen-3-yl)-2-(phenylsulfonyl)ethylidene)
semicarbazide (4f). Yield 85%, mp 210–213◦C. IR (KBr, γ max cm−1): 1164, 1344
(SO2), 1460 (C N), 1683 (NHCO), 1720 (C O of lactone), 3201 (CONH2), 3404
(NHCO), 1H NMR (CDCl3+DMSO-d6, δ ppm): 4.55 (s, 2H CH2), 7.20–7.62 (m,
13H, Ar H and NH2), 8.05 (s, 1H, C4 of coumarin), 8.9 (br, s, NH). Anal. Calcd. for
C22H17N3O5S: C, 60.68; H, 3.93; N, 9.65. Found: C, 60.63; H, 3.90; N, 9.68%.
(1Z)-1-(1-(2-Oxo-2H-chromen-3-yl)-2-tosyl)ethylidene)semicarbazide
(4g). Yellow solid, yield 94%, mp 238–240◦C. IR (KBr, γ max cm−1): 1148, 1318
(SO2),1455 (C N), 1690 (NHCO), 1725 (C O of lactone), 3316 (CONH2), 3466
1
(NHCO), H NMR (DMSO-d6, δ ppm): 2.12 (s, 3H, CH3), 5.16 (s, 2H CH2), 6.65 (s,
2H,NH2), 7.24–7.27 (m, 2H, Ar H), 7.39–7.41 (m, 2H, Ar H), 7.65–7.76 (m, 4H,
Ar H), 8.20 (s, 1H, C4 of coumarin), 10.20 (s, 1H,NH) EI-MS 400 (M+H)+. Anal. Calcd.
for C19H17N3O5S: C, 57.13; H, 4.29; N, 10.52. Found: C, 57.10; H, 4.24; N, 10.50%.
(1Z)-1-(1-(6-Bromo-2-oxo-2H-chromen-3-yl)-2-tosyl)ethylidene)semicar
bazide (4h). Yield 90%, mp 222–224◦C. IR (KBr, γ max cm−1): 1146, 1303 (SO2),
1459 (C N), 1723 (NHCO), 1732 (C O of lactone), 3205 (CONH2), 3376 (NHCO),
1H NMR (DMSO-d6, δ ppm): 2.4 (s, 3H, CH3), 4.70 (s, 2H, CH2), 7.20–7.65 (m, 9H,
Ar H and NH2), 8.42 (s, 1H, C4 of coumarin proton), 9.30 (br, s, NH). Anal. Calcd. for
C19H16BrN3O5S: C, 47.71; H, 3.37; N, 8.79. Found: C, 47.74; H, 3.39; N, 8.70%.
(1Z)-1-(1-(6,8-Dibromo-2-oxo-2H-chromen-3-yl)-2-tosyl)ethylidene)semi
carbazide (4i). Yield 88%, mp 236–238◦C. IR (KBr, γ max cm−1): 1143, 1319 (SO2),
1475 (C N), 1702 (NHCO), 1720 (C O of lactone), 3206 (CONH2), 3439 (NHCO), 1H
NMR (DMSO-d6, δ ppm): 2.41 (s, 3H, CH3),4.90 (s, 2H CH2), 7.25–7.60 (m, 8H, Ar H
and NH2), 8.42 (s, 1H, C4 of coumarin), 9.80 (br, s, NH) Anal. Calcd. for C19H15Br2N3O5S:
C, 40.95; H, 2.71; N, 7.54. Found: C, 40.98; H, 2.74; N, 7.51%.
(1Z)-1-(1-(6-Chloro-2-oxo-2H-chromen-3-yl)-2-tosyl)ethylidene)semicar
bazide (4j). Yield 91%, mp 230◦C. IR (KBr, γ max cm−1): 1144, 1320 (SO2), 1453
(C N), 1702 (NHCO), 1720 (C O of lactone), 3250 (CONH2), 3438 (NHCO), 1H NMR
(DMSO-d6, δ ppm): 2.2 (s, 3H,CH3), 4.70 (s, 2H, CH2), 7.12–7.50 (m, 9H, Ar H and
NH2), 8.40 (s, 1H, C4 of coumarin), 9.34 (br, s,1H, NH). Anal. Calcd. for C19H16ClN3O5S:
C, 56.60; H, 3.72; N, 9.69. Found: C, 56.62; H, 3.74; N, 9.65%.
(1Z)-1-(1-(6,8-Dichloro-2-oxo-2H-chromen-3-yl)-2-tosyl)ethylidene)semi
carbazide (4k). Yield 89%, mp 220–222◦C. IR (KBr, γ max cm−1): 1135, 1358 (SO2),
1475 (C N), 1692 (NHCO), 1734 (C O of lactone), 3200 (CONH2), 3415 (NHCO), 1H
NMR (DMSO-d6, δ ppm): 2.42 (s, 3H,CH3), 4.90 (s, 2H CH2), 7.2–7.6 (m, 8H, Ar H and

SULFONE-LINKED 3-([1,2,3]-THIADIAZOL-4-YL)-CHROMEN-2-ONES
365
NH2), 8.41 (s, 1H, C4 of coumarin), 9.80 (br, s, NH) Anal. Calcd. for C19H15Cl2N3O5S:
C, 48.73; H, 3.23; N, 8.97. Found: C, 48.70; H, 3.20; N, 8.94%.
(1Z)-1-(1-(2-Oxo-2H-benzo[h]chromen-3-yl)-2-tosylethylidene)semicar
bazide (4l). Yield 82%, mp 198–200◦C. IR (KBr, γ max cm−1): 1144, 1321 (SO2), 1434
(C N), 1684 (NHCO), 1721 (C O of lactone), 3188 (CONH2), 3436 (NHCO), 1H NMR
(DMSO-d6, δ ppm): 2.40 (s, 3H, CH3), 4.60 (s, 2H CH2), 7.21–7.73 (m, 12H, Ar H and
NH2), 8.40 (s, 1H, C4 of coumarin), 9.02 (br, s, NH). Anal. Calcd. for C23H19N3O5S: C,
61.46; H, 4.26; N, 9.35. Found: C, 61.42; H, 4.29; N, 9.38%.
3-(5-(Phenylsulfonyl)-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one (5)
Semicarbzone 4 (0.001 mol) was added portionwise to the thionylchloride (1.5 ml) at
0–5◦C.Then the mixture was heated at reflux temperature over 4 h. The reaction mixture was
cooled to room temperature, and the reaction mixture decomposed with saturated sodium
carbonate solution. The solid that separated was filtered, washed with water, dried, and
purified by column chromatography (silica gel 60–120 mesh,, hexane:ethylacetate, 8:2).
3-(5-(Phenylsulfonyl)-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one
(5a).
Yield 92%, mp 110–112◦C. IR (KBr, γ max cm−1): 1152, 1331 (SO2), 1446 (N N), 1608
1
(C C), 1723 (C O of lactone), H NMR (CDCl3, δ ppm): 7.41–7.69 (m, 9H, Ar H),
8.14 (s, 1H, C4 of coumarin) EI-MS 371 (M+H)+. Anal. Calcd. for C17H10N2O4S2:
C,55.12; H, 2.72; N,7.56. Found: C,55.10; H,2.75; N, 7.52%.
6-Bromo-3-(5-(phenylsulfonyl)-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one
(5b). Yield 90%, mp 122–123◦C.IR (KBr, γ max cm−1): 1156, 1346 (SO2), 1447 (N N),
1
1619 (C C), 1746 (C O of lactone), H NMR (CDCl3, δ ppm): 7.62–7.90 (m, 8H,
Ar H), 9.05 (s, 1H, C4 of coumarin) Anal. Calcd. for C17H9BrN2O4S2: C, 45.44; H, 2.02;
N, 6.23. Found: C, 45.41; H, 2.00; N, 6.26%.
6,8-Dibromo-3-(5-(phenylsulfonyl)-1,2,3-thiadiazol-4-yl)-2H-chromen-2-
one (5c). Yield 90%, mp 156–158◦C. IR (KBr, γ max cm−1): 1156, 1330 (SO2), 1446
1
(N N), 1602 (C C), 1735 (C O of lactone), H NMR (CDCl3, δ ppm): 7.35–8.0 (m,
7H, Ar H), 8.06 (s, 1H, C4 of coumarin). Anal. Calcd. for C17H8Br2N2O4S2: C, 38.66;
H, 1.53; N, 5.30; Found: C, 38.68; H, 1.50; N, 5.32%.
6-Chloro-3-(5-(phenylsulfonyl)-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one
(5d). Yield 92%, mp 118–120◦C. IR (KBr, γ max cm−1): 1156, 1325 (SO2), 1447 (N N),
1
1607 (C C), 1734 (C O of lactone), H NMR (CDCl3, δ ppm): 7.51–7.58 (m, 6H,
Ar H), 7.79–7.80 (m, 2H, Ar H), 8.20 (s, 1H, C4 of coumarin). Anal. Calcd. for
C17H9ClN2O4S2: C, 50.43; H, 2.24; N, 6.92. Found: C, 50.45; H, 2.26; N, 6.95%.
6,8-Dichloro-3-(5-(phenylsulfonyl)-1,2,3-thiadiazol-4-yl)-2H-chromen-2-
one (5e). Yield 89%, mp 142–144◦C. IR (KBr, γ max cm−1): 1156, 1324 (SO2), 1447
1
(N N), 1606 (C C), 1725 (C O of lactone), H NMR (CDCl3, δ ppm): 7.40–7.69 (m,
7H, Ar H), 8.14 (s, 1H, C4 of coumarin). Anal. Calcd. for C17H8Cl2N2O4S2: C, 46.48;
H, 1.84; N, 6.38. Found: C, 46.40; H, 1.90; N, 6.42%.
3-(5-(Phenylsulfonyl)-1,2,3-thiadiazol-4-yl)-2H-benzo[h]chromen-2-one
(5f). Yield 84%, mp 178–180◦C. IR (KBr, γ max cm−1): 1156, 1331 (SO2), 1438 (N N),
1627 (C C), 1726 (C O of lactone),1H NMR (CDCl3, δ ppm): 7.50–7.90 (m, 11H,
Ar H), 8.95 (s, 1H, C4 of coumarin).Anal. Calcd. for C21H12N2O4S2: C, 59.99; H, 2.88;
N, 6.66; Found: C, 59.96; H, 2.86; N, 6.69%.
3-(5-Tosyl-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one (5g). Yield 94%, mp
124–126◦C. IR (KBr, γ max cm−1): 1156, 1330 (SO2), 1454 (N N), 1608 (C C), 1729

366
N. GURAVAIAH AND V. RAJESWAR RAO
(C O of lactone), 1H NMR (CDCl3, δ ppm): 2.75 (s, 3H, CH3), 7.12–7.40 (m, 8H, Ar H),
8.42 (s, 1H, C4 of coumarin), EI-MS 385 (M+H)+. Anal. Calcd. for C18H12N2O4S2: C,
56.24; H, 3.15; N, 7.29; Found: C, 56.28; H, 3.18; N, 7.27%.
6-Bromo-3-(5-tosyl-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one (5h). Yield
91%, mp 138–140◦C. IR (KBr, γ max cm−1): 1156, 1332 (SO2), 1451 (N N), 1601 (C C),
1
1735 (C O of lactone), H NMR (CDCl3, δ ppm): 2.43 (s, 3H, CH3), 7.31–7.34 (m,
2H, Ar H), 7.69–7.84 (m, 5H, Ar H), 9.05 (s, 1H, C4 of coumarin), Anal. Calcd. for
C18H11BrN2O4S2: C, 46.66; H, 2.39; N, 6.05; Found: C, 46.68; H, 2.44; N, 6.00%.
6,8-Dibromo-3-(5-tosyl-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one
(5i).
Yield 85%, mp 145–146◦C. IR (KBr, γ max cm−1): 1155, 1326 (SO2), 1444 (N N), 1615
(C C), 1736 (C O of lactone), 1H NMR(CDCl3, δ ppm): 2.46 (s, 3H, CH3), 7.20–7.30
(m, 3H, Ar H), 7.70–7.8 (m, 3H, Ar H), 8.05 (s, 1H, C4 of coumarin). Anal. Calcd. for
C18H10Br2N2O4S2: C, 39.87; H, 1.86; N, 5.17; Found: C, 39.89; H, 1.88; N, 5.19%.
6-Chloro-3-(5-tosyl-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one (5j). Yield
88%, mp 136–138◦C. IR (KBr, γ max cm−1): 1154, 1326 (SO2), 1455 (N N), 1606 (C C),
1732 (C O of lactone), 1H NMR (CDCl3, δ ppm): 2.70 (s, 3H, CH3), 7.20–7.40 (m,
2H, Ar H), 7.60–7.75 (m, 5H, Ar H), 8.52 (s, 1H, C4 of coumarin). Anal. Calcd. for
C18H11ClN2O4S2: C, 51.61; H, 2.65; N, 6.69; Found: C, 51.63; H, 6.67; N, 2.68%.
6,8-Dichloro-3-(5-tosyl-1,2,3-thiadiazol-4-yl)-2H-chromen-2-one
(5k).
Yield 88%, mp 128–130◦C. IR (KBr, γ max cm−1): 1125, 1333 (SO2), 1447 (N N), 1605
1
(C C), 1726 (C O of lactone), H NMR (CDCl3, δ ppm): 2.40 (s, 3H, CH3), 7.2–7.4
(m, 2H, Ar H), 7.60–7.90 (m, 4H, Ar H), 8.40 (s, 1H, C4 of coumarin).Anal. Calcd. for
C18H10Cl2N2O4S2: C, 47.69; H, 2.22; N, 6.18; Found: C, 47.67; H, 2.24; N, 6.21%.
3-(5-Tosyl-1,2,3-thiadiazol-4-yl)-2H-benzo[h]chromen-2-one (5l). Yield
80%, mp 188–190◦C. IR (KBr, γ max cm−1): 1127, 1343 (SO2), 1414 (N N), 1623 (C C),
1716 (C O of lactone), 1H NMR (CDCl3, δ ppm): 2.29 (s, 3H, CH3), 7.10–7.20 (m, 10H,
Ar H), 7.96 (s, 1H, C4 of coumarin). Anal. Calcd. for C22H14N2O4S2 C, 60.82; H, 3.25;
N, 6.45; Found: C, 60.84; H, 3.21; N, 6.42%.
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