Synthesis of benzensulfonamides linked to quinazoline scaffolds as novel carbonic anhydrase inhibitors

Article abstract of DOI:10.1016/j.bioorg.2019.03.007

Carbonic anhydrase (CA) inhibitory activities of newly synthesized quinazoline-linked benzensulfonamides 10–29, 31, 32, 35, 36, and 45–51 against human CA (hCA) isoforms I, II, IX, and XII were measured and compared to that of acetazolamide (AAZ) as a standard inhibitor. Potent selective inhibitory activity against hCA I was exerted by compounds 14, 15, 17, 19, 20, 21, 24, 25, 28, 29, 31, 35, 45, 47, 49, and 51 with inhibition constant (K_Is) values of 39.4–354.7 nM that were nearly equivalent or even greater than that of AAZ (K_I, 250.0 nM). Compounds 15, 20, 24, 28, 29, 45 and 47 proved to have inhibitory activities against hCA II with (K_Is, 0.73–16.5 nM) that were similar or improved to that of AAZ (K_I, 12.0 nM). Compounds 13–29, 31–32, and 45–51 displayed potent hCA IX inhibitory activities (K_Is, 1.6–32.2 nM) that were more effective than or nearly equal to AAZ (K_I, 25.0 nM). Compounds 14, 15, 20, 21, 26, 45, and 47 exerted potent hCA XII inhibitory activities (K_Is, 5.2–9.2 nM), indicating similar CAI activities as compared to that of AAZ (K_I, 5.7 nM).

Full text of DOI:10.1016/j.bioorg.2019.03.007

Accepted Manuscript
Synthesis of benzensulfonamides linked to quinazoline scaffolds as novel car-
bonic anhydrase inhibitors
Adel S. El-Azab, Alaa A.-M. Abdel-Aziz, Sivia Bua, Alessio Nocentini, Manal
A. El-Gendy, Menshawy A. Mohamed, Taghreed Z. Shawer, Nawaf A. AlSaif,
Claudiu T. Supuran
PII:
S0045-2068(18)31397-X
https://doi.org/10.1016/j.bioorg.2019.03.007
YBIOO 2833
DOI:
Reference:
Bioorganic Chemistry
To appear in:
Received Date:
Revised Date:
Accepted Date:
30 November 2018
30 January 2019
3 March 2019
Please cite this article as: A.S. El-Azab, A.A. Abdel-Aziz, S. Bua, A. Nocentini, M.A. El-Gendy, M.A. Mohamed,
T.Z. Shawer, N.A. AlSaif, C.T. Supuran, Synthesis of benzensulfonamides linked to quinazoline scaffolds as novel
carbonic anhydrase inhibitors, Bioorganic Chemistry (2019), doi: https://doi.org/10.1016/j.bioorg.2019.03.007
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1
Graphical Abstract
Synthesis of benzensulfonamides linked to quinazoline
scaffolds as novel carbonic anhydrase inhibitors
Adel S. El-Azab*, Alaa A.-M. Abdel-Aziz, Silvia Bua, Alessio Nocentini,
Manal A. El-Gendy, Menshawy A. Mohamed, Taghreed Z. Shawer, Nawaf A. AlSaif, Claudiu T. Supuran*
Compounds 15, 45, 47, and 26 exhibited potent selective inhibitory activity against human isoforms CA I,
II, IX, and XII (K⁠Is: 39.4, 0.73, 1.6, and 5.2 nM, respectively), comparable to that of acetazolamide
(AAZ) as a standard inhibitor (K⁠I: 250.0, 12.0, 25.0, and 5.7 nM respectively).

2
Highlights
Quinazoline-linked benzensulfonamides with CA inhibitory activity were synthesized
Newly synthesized compounds potently inhibit human isoforms CA I, II, IX and XII
Inhibitory activity of new compounds was comparable to that of CA inhibitor AAZ.
Compounds 14-15, 17, 19-21, 24-25, 28-29, 31, 35, 45, 47, 49&51 inhibit hCA I (K⁠Is: 39.4-354.7 nM)
Compounds 15, 20, 24, 28, 29, 45, and 47 inhibit hCA II (K⁠Is: 0.73-16.5 nM)
Compounds 13-29, 31-32, and 45-51 inhibit hCA IX (K⁠Is: 1.6-32.2 nM)
Compounds 14, 15, 20, 21, 26, 45, and 47 inhibit hCA XII (K⁠Is: 5.2-9.2 nM)

3
Synthesis of benzensulfonamides linked to quinazoline scaffolds as novel carbonic
anhydrase inhibitors
Adel S. El-Azab*a,b, Alaa A.-M. Abdel-Aziza,c, Sivia Buad, Alessio Nocentinid, Manal A. El-Gendya,
Menshawy A. Mohamedb,e, Taghreed Z. Shawerf, Nawaf A. AlSaifa, Claudiu T. Supuran*d
aDepartment of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
bDepartment of Organic Chemistry, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt
cDepartment of Medicinal Chemistry, Faculty of Pharmacy, University of Mansoura, Mansoura, Egypt
dUniversità degli Studi di Firenze, Dipartimento Neurofarba, Sezione di Scienze Farmaceutiche e Nutraceutiche, Via U. Schiff 6,
50019 Sesto Fiorentino, Florence, Italy.
eDepartment of Pharmaceutical Chemistry, College of Pharmacy, Salman Bin Abdulaziz University, AlKharj, Saudi Arabia
fDepartment of Pharmaceutical Chemistry, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt.
Abstract. Carbonic anhydrase (CA) inhibitory activities of newly synthesized quinazoline-linked
benzensulfonamides 10-29, 31, 32, 35, 36, and 45-51 against human CA (hCA) isoforms I, II, IX, and XII were
measured and compared to that of acetazolamide (AAZ) as a standard inhibitor. Potent selective inhibitory activity
against hCA I was exerted by compounds 14, 15, 17, 19, 20, 21, 24, 25, 28, 29, 31, 35, 45, 47, 49, and 51 with
inhibition constant (K⁠Is) values of 39.4-354.7 nM that were nearly equivalent or even greater than that of AAZ
(K⁠I, 250.0 nM). Compounds 15, 20, 24, 28, 29, 45 and 47 proved to have inhibitory activities against hCA II with
(K⁠Is, 0.73-16.5 nM) that were similar or improved to that of AAZ (K⁠I, 12.0 nM). Compounds 13-29, 31-32, and
45-51 displayed potent hCA IX inhibitory activities (K⁠Is, 1.6-32.2 nM) that were more effective than or nearly
equal to AAZ (KI, 25.0 nM). Compounds 14, 15, 20, 21, 26, 45, and 47 exerted potent hCA XII inhibitory activities
(K⁠Is, 5.2-9.2 nM), indicating similar CAI activities as compared to that of AAZ (K⁠I, 5.7 nM).
Keywords: Synthesis, Quinazoline scaffolds, Benzenesulfonamide, Carbonic anhydrase inhibition, Acetazolamide
⁎ Corresponding authors:
Adel S. El-Azab, Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh
11451, Saudi Arabia; E-mail: adelazab@ksu.edu.sa
Claudiu T. Supuran, University of Florence; Tel/Fax.: +39-055-4573729; E-mail: claudiu.supuran@unifi.it

4
1. Introduction
Most organisms possess multiple isoforms of carbonic anhydrase (CA, EC 4.2.1.1), a family of
zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide to bicarbonate and
protons [1-4]. This hydration reaction is involved in several vital physiological pathways [1-4]
and deregulation of CA activity is associated with disorders and diseases such as glaucoma [4],
epilepsy [5], obesity [6], and cancer [7].
Human carbonic anhydrase inhibitors (hCAI) compounds have various therapeutic applications.
For example, human CA (hCA) II, IV, and XII inhibitors are used as diuretics and in glaucoma.
The hCA II and VII inhibitors are used as anti-epileptic drugs [1, 2, 8], whereas certain antitumor
and anti-inflammatory CAIs target the isoforms hCA IX and XII. Recently, hCA IV, IX, and XII
were shown to be involved in rheumatoid arthritis and their cognate inhibitors may constitute
new pharmacological candidates for the management of this condition [1, 9, 10]. Furthermore,
the transmembrane isoforms hCA IX/XII are overexpressed in many hypoxic tumors [11-15].
Sulfonamides are one of the best studied CAI classes [16-24], whereas some of them, such as the
coxibs, celecoxib, and valdecoxib, also inhibit cyclooxygenase (COX) [25, 26].
The quinazolinone scaffold is frequently used in medicinal chemistry [26-45]. Several 2-[(3-
substituted-4(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)acetamides (A) are highly
potent, nanomolar inhibitors of -CA from Vibrio cholerae (VchCA) and the human -CA
isoforms hCA
I
and hCA II
[46]
(Figure 1).
Three
4-(quinazolin-4-
ylamino)benzenesulfonamides and 4-(quinazolin-4-yloxy)benzenesulfonamide (B) exerted
strong inhibitory effects against the cytosolic hCA I and II and the transmembrane hCA IX and
XII, with K⁠Is values in the low nanomolar range [47] (Figure 1).

5
3-(3-Aminosulfonyl)-phenyl-2-mercapto-6-iodo-4(3H)quinazolinone
and
3-(2-mercapto-7-
flouro-4(3H)quinazolinon-3-yl)-benzenesulfonamide (C) were potent inhibitors of the tumor-
associated isoforms hCA IX (K⁠Is, 1.5 and 2.7 nM, respectively) and XII (K⁠Is, 0.57 and 1.9
nM, respectively) [48].
3-(4-Aminosulfonyl)-phenyl-2-mercapto-substituted-4(3H)quinazolinones (C) are highly potent
inhibitors of hCA I (K⁠Is = 135–282 nM), hCA II (K⁠Is = 0.25–10.8 nM), IX (K⁠Is of 3.7–
50.4 nM), and XII (K⁠Is of 0.60–52.9 nM) [49].
Based on the aforementioned rationale, we designed and synthesized a new series of 2-
substituted-mercapto-3-substituted-4(3H)-quinazolinones by incorporating benzenesulfonamide
moieties 10-29, 31, 32, 35, 36, and 45-51 and assayed their inhibitory effects on four
physiological significant hCA isoforms, the abundantly expressed, cytosolic hCA I and II and the
tumor-associated hCA IX and XII (D, E, and F; Figure 1) as CAI lead compounds.
2. Results and discussion
2.1. Chemistry
2-[(3-Benzyl-6-substituted-4(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)acetamides, 2-
[(3-benzyl-6-substituted-4(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)propanamides
(10-19),
2-[(3-benzyl-6-substituted-4(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenethyl)acetamides and 2-[(3-benzyl-6-substituted-4(3H)-quinazolinon-2-yl)thio]-N-
(4-sulfamoylphenethyl)propanamides (20-29) were obtained with a yield of 87-96% by reacting
the appropriate 6-substituted-2-mercapto-3-substituted-4(3H)-quinazolinones (1-5) with 2-
chloro-N-(4-sulfamoylphenyl)amides (6-7) or 2-chloro-N-(4-sulfamoylphenethyl)amides (8-9) in
acetone containing anhydrous potassium carbonate (Scheme 1). Multiple spectral analyses were

6
performed to confirm the structures of target compounds 10-29. The amide moiety (CONH) of
1
compounds 10-29 was verified by H NMR spectra with a peak for the amidic proton at 10.92-
8.34 ppm and by 13C NMR spectra with characteristic peaks at 170.80-166.63 ppm for the
carbonyl group. The 3-benzylquinazolinone moiety was verified by a peak at 5.66-5.25 and at
49.09-47.20 ppm of CH2Ph group in the 1H NMR and 13C NMR spectra, as well as a typical peak
at 161.35-159.99 ppm of carbonyl group of quinazolinone moiety in the 13C NMR spectra.
Compounds 10, 12, 14, 16, 18, 20, 22, 24, 26, and 28 were confirmed by the presence of singlet
peaks for two protons of the acetamide group (SCH2CONH) at 4.23-3.95 ppm and at 40.72-37.41
ppm in the 1H NMR and 13C NMR spectra. Moreover, the propanamide moiety
(S(CH)CH3CONH) of compounds 11, 13, 15, 17, 19, 21, 23, 25, 27, and 29 was confirmed by a
singlet proton peak at 4.77-4.51 ppm and a carbonyl group peak at 47.25-46.10 ppm in the
1HNMR and 13C NMR spectra, respectively, as well as by verifying the methyl group with a
1
doublet peak at 1.60-1.45 in the H NMR and a peak at 18.77-17.57 ppm in the 13C NMR.
Compounds 20-29 were characterized by the presence of the ethylsulfonamide moiety indicated
1
by two peaks at 2.97-2.77 and 3.38-3.28 ppm in the H NMR spectra and at 35.24-35.03 and
13
40.50.38-36.24 ppm in the C NMR spectra (Scheme 1). Moreover, the reaction of 2-mercapto-
3-(3,4,5-trimethoxybenzyl)-4(3H)-quinazolinone
(30)
with
either
2-chloro-N-(4-
sulfamoylphenyl)amides (6-7) or 2-chloro-N-(4-(sulfamoylmethyl)phenyl)amides (33-34) had a
yield of 81% for either 2-[(3-(3,4,5-trimethoxybenzyl)-4(3H)quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenyl)acetamide (31) and 2-[(3-(3,4,5-trimethoxybenzyl)-4(3H)quinazolinon-2-
yl)thio]-N-(4-sulfamoylphenyl) propanamide (32) or 2-((3-(3,4,5-trimethoxybenzyl)-4(3H)-
quinazolinon-2-yl)thio)-N-(4-sulfamoylphenyl)acetamide
(35)
and
2-((3-(3,4,5-
trimethoxybenzyl)-4(3H)-quinazolinon-2-yl)thio)-N-(4-sulfamoylphenyl)propanamide
(36),

7
respectively [45] (Scheme 2). Furthermore, 3-substituted-4-(3H)-quinazolinon-2-yl-2-oxo-N-(4-
sulfamoylphenyl)propanehydrazonothioates (45-51) were obtained with a yield of 80-85% by
heating
3-substituted-2-mercapto-4(3H)-quinazolinones
(37-43)
and
2-oxo-N-(4-
sulfamoylphenyl)propanehydrazonoyl chloride (44) in dioxane containing triethylamine (Scheme
3). Compounds 45-51 were verified by a singlet peak for the NH group of the hydrazone moiety
(-NH-N=C-) at 11.10-10.30 ppm in the 1H NMR spectra, as well as a peak at 192.77-189.59 ppm
for the carbonyl group of the propanehydrazonothioate moiety (-NH-N=CS-COCH3) in the 13C
NMR spectra. In addition, the methyl group of the propanehydrazonothioate moiety (-NH-
N=CS-COCH3) was identified by a characteristic singlet peak at 2.61-2.55 and a peak at 26.30-
1
25.48 ppm in the H NMR and 13C NMR spectra, respectively, as well as a typical peak at
165.57-161.45 ppm for the carbonyl group of the 3-substituted quinazolinone moiety in the 13C
NMR spectra.
2.2. CA inhibitory activity
The CAI activity of newly synthesized compounds (10-29, 31, 32, 35, 36 and 45-51) against
isoforms hCA I, II, IV, and IX was measured and compared to that of acetazolamide (AAZ), a
standard sulfonamide inhibitor. Regarding the CAI activity toward individual hCA isoforms,
hCA I was effectively inhibited by compounds 14, 15, 17, 19, 20, 21, 24, 25, 28, 29, 31, 35, 45,
47, 49, and 51 with inhibition constant (KI) values in the range of 39.4-353.8 nM, (AAZ: KI,
250.0 nM). Compounds 12, 13, 16, 18, 22, 23, 26, 27, 32, 35, 36, 46, 48, and 50 showed
moderate hCA I inhibitory activity with KI values of 421.9-700.5 nM. In contrast, 10 and 11 had
a weak inhibitory activity with a K⁠Is of 3665.4 and 6472.2 nM, respectively. Compounds 12,
13, 14, 15, 20, 21, 24, 25, 27, 28, 29, 45, and 47 proved to be potent hCA II inhibitors, with KI
values of 0.73-28.4 nM, which were greater than or nearly equal to that of AAZ (KI, 12.0 nM).

8
Compounds 16, 17, 18, 19, 22, 23, and 26 showed moderate hCA II inhibitory activity with K⁠Is
ranging between 32.4 and 78.3 nM whereas compounds 10, 11, 31, 32, 35, 36, 46, 48, 49, 50,
and 51 showed a weak inhibitory activity with K⁠Is in the range of 151.7-833.1 nM. Compounds
13-29, 31-32, and 45-51 displayed potent selective hCA IX inhibitory activity with K⁠ values
I
ranging from 1.6 to 32.2 nM, being more effective than or nearly equivalent to AAZ. Against
hCA IX, compounds 12, 35 and 36 exhibited moderate inhibitory activity, with K⁠ values of
I
65.5, 163.3, and 113 nM, respectively. Weak hCA IX inhibition was also observed for
compounds 10 and 11 with K⁠Is values of 210.9 and 262.4 nM, respectively. Derivatives 14, 15,
20, 21, 26, 45, and 47 possessed potent hCA XII inhibitory activities with K⁠ values of 5.2-9.2
I
nM, exerting an activity that was improved or nearly equivalent to that of AAZ (K⁠I, 5.7 nM).
Compounds 12, 13, 22, 23, 24, 25, 27, 28, 29, and 51 exerted weaker hCA XII inhibitory
activities with K⁠ values of 12.1-40.6 nM whereas compounds 10, 11, 16, 17, 18, 19, 31, 32,
I
35, 36, 46, 48, 49 and 50 had weak hCA XII inhibitory activities with K⁠ values in the range of
I
42.5-149.4 nM (Table 1).
2.3. Structure-activity relationship analysis
(I)
The inhibition tests of hCA isoforms with compounds 10-29 and 45-51 (Table 1),
showed that 6-substituted and 6,7-dimethoxyquinazoline derivatives 12-19 were more
active than the unsubstituted derivatives 10 and 11 toward hCA isoforms; 3-phenyl
unsubstituted quinazoline propanehydrazonothioate 45 and 6-methoxyquinazoline
propanehydrazonothioate 47 were the most active derivatives among the
propanehydrazonothioates (45-51) toward hCA isoforms.
(II)
Structure-activity relationship analysis for hCA I inhibition indicated that 1) the
introduction of electron withdrawing groups such as 6-Cl or 6-I at the quinazoline

9
moiety of compound 10 and 11 (K⁠Is of 3665.4 and 6472.2 nM) produced
compounds 12, 13, 16, and 17 with strongly increased the CAI activity (K⁠Is ,
254.4-764.1 nM); 2) the introduction of electron donating groups such as the methyl
group at position 6 or the methoxy groups at positions 6 and 7 of the quinazoline
nucleus produced compounds 14, 15, 18, and 19 with significantly improved CAI
potency (K⁠Is, 225.6, 39.4, 421.9, and 219.0 nM, respectively); 3) 6,7-
dimethoxyquinazolines 14 and 15 (K⁠Is, 225.6 and 39.4 nM) were more potent than
6-methylquinazolines 18 and 19 (K⁠Is, 421.9 and 219.0 nM); 4) propanamides such
as 15, 17, and 19 (K⁠Is, 39.4, 254.4, and 219.0 nM, respectively) were more effective
than the corresponding acetamides 14, 16, and 18 (K⁠Is, 225.6, 642.2, and 421.9 nM,
respectively); 5) unsubstituted quinazoline derivatives such as 20 and 21 (K⁠Is, 78.2
and 136.5 nM) were more active than the corresponding 6-substituted and 6,7-
dimethoxyquinazoline derivatives 22-29 (K⁠Is, 106.3-617.4 nM); 6) the introduction
of electron withdrawing groups such as 6-Cl and 6-I at the quinazoline moiety of
compounds 20 or 21 produced compounds 22, 23 and 26, 27 with remarkably
decreased CAI activity (K⁠Is, 617.4, 453.1 and 494.5, 488.6 nM, respectively); 7) the
introduction of electron donating groups such as the 6,7-dimethoxy groups or the 6-
methyl group at the quinazoline nucleus of compounds 20 and 21 produced
compounds 24, 25 and 28, 29 with non-significantly decreased CAI potency (K⁠Is,
307.1, 353.8 and 106.3, 268.1 nM respectively); 8) unsubstituted and 6-substituted
quinazoline ethylslfonamide derivatives such as compounds 20-23, 26, and 28 (K⁠Is,
78.2, 136.5, 617.4, 453.1, 494.5, and 106.3 nM, respectively) were more active than
the corresponding sulfonamide derivatives 10-13, 16, and 18 (K⁠Is, 3665.4, 6472.2,

10
645.7, 764.1, 642.2, and 421.9 nM, respectively); on the other hand, 6,7-
dimethoxyquinazoline sulfonamides 14, 15, 6-iodo quinazoline sulfonamide 17, and
6-methylquinazoline sulfonamide 19 (K⁠Is, 225.6, 39.4, 254.4, and 219.0 nM,
respectively) were more active than the corresponding ethylsulfonamide derivatives
24, 25, 27, and 29 (K⁠Is, 307.1, 353.8, 488.6, and 268.1 nM, respectively); 9)
acetamide derivatives 31 and 35 (K⁠Is, 215.5 and 354.7 nM) were more active than
propanamides 32 and 36 (K⁠Is, 609.3 and 747.7 nM); 10) the introduction of chloro,
methyl or nitro groups at the 6-position of quinazoline moiety in
propanehydrazonothioate 45 (KI, 86.6 nM) produced propanehydrazonothioates 46,
48, and 49 (K⁠Is, 428.7, 631.0, and 328.4 nM, respectively) with remarkably
decreased the hCA I inhibitory activity, whereas the introduction of the methoxy
group at the 6-position of quinazoline moiety for propanehydrazonothioate 45
generated compound 47 (KI, 83.9 nM) with barely increased hCA I inhibitory
activity; 11) 3-phenyl unsubstituted quinazoline propanehydrazonothioate 45 (KI,
86.6 nM) was more active than 3-benzyl unsubstituted quinazoline
propanehydrazonothioate 50 (KI, 700.5 nM) and 3-benzyl-6-methylquinazoline
propanehydrazonothioate 51 (KI, 201.1 nM) was more active than 3-phenyl-6-
methylquinazoline propanehydrazonothioate 48 (KI, 631.0 nM).
(III) Structure-activity relationship analysis for hCA II inhibition indicated that 1) anilides
12-15 (KI, 3.3-28.4 nM) were more effective than the corresponding compounds 16-
19 (K⁠Is, 32.4-78.3 nM); 2) 6,7-dimethoxyquinazoline 15 (KI, 3.3 nM) showed a
higher hCA II inhibitory activity than 6-chloroquinazolines 12 and 13 (K⁠Is, 27.6
and 22.8 nM); 3) propanamides derivatives such as compounds 13, 15, 17, and 19

11
(K⁠Is, 22.8, 3.3, 62.7, and 32.4 nM, respectively) were more effective than the
corresponding acetamides 12, 14, 16, and 18 (K⁠Is, 27.6, 28.4, 78.3, and 53.0 nM,
respectively); 4) the inhibitory activity of unsubstituted quinazoline derivatives 20
and 21 (K⁠Is, 15.5 and 21.2 nM) was similar to that of AAZ (KI, 12.0 nM); 5) the
introduction of electron withdrawing groups such as 6-Cl or 6-I at the quinazoline
moiety produced compounds 22, 23 and 26, 27 with remarkably decreased the CAI
activity (K⁠Is, 55.3, 50.9 and 35.0, 26.3 nM, respectively); 6) the introduction of
electron donating groups such as 6,7-dimethoxy groups at the quinazoline moiety
generated compounds 24 and 25 without a change in CAI potency (K⁠Is, 16.5 and
22.6 nM) whereas the addition of the 6-methyl function to the quinazoline nucleus
produced compounds 28 and 29 with significantly increased CAI potency (K⁠Is, 6.9
and 5.2 nM); 7) unsubstituted quinazoline ethylsulfonamides 20, 21, 6,7-
dimethoxyquinazoline ethylsulfonamide 24, 6-iodoquinazoline ethylsulfonamides 26,
27, and 6-methylquinazoline ethylsulfonamides 28, 29 (K⁠Is, 15.5, 21.2, 16.5, 35.0,
26.3, 6.9, and 5.2 nM, respectively) were more active than the corresponding
sulfonamide derivatives 10, 11, 14, and 16-19 (K⁠Is, 547.7, 591.1, 28.4, 78.3, 62.7,
53.0, and 32.4 nM, respectively); on the other hand, 6-chloroquinazoline
sulfonamides 12, 13, and 6-7-dimethoxyquinazoline sulfonamide 15 (K⁠Is, 27.6,
22.8, and 3.3 nM) were more active than the corresponding ethylsulfonamide
derivatives 22, 23, and 25 (K⁠Is, 55.3, 50.9, and 22.6 nM, respectively); 8) the
anilides of benzensulfonamides 31 and 32 (K⁠Is, 218.7 and 151.7 nM) were more
potent than the corresponding anilides of benzylsulfonamides 35 and 36 (K⁠Is, 484.8
and 833.1 nM); 9) 3-phenyl unsubstituted quinazoline propanehydrazonothioate 45

12
(Ki, 86.6 nM) was more active than 3-phenyl 6-substituted quinazoline
propanehydrazonothioates 46-49 (K⁠Is, 6.2-320.1 nM); 10) 3-phenyl unsubstituted
quinazoline propanehydrazonothioate 45 and 3-phenyl-6-methylquinazoline
propanehydrazonothioate 48 (K⁠Is, 0.73 and 188.3 nM) were more active than 3-
benzyl unsubstituted quinazoline propanehydrazonothioate 50 and 3-benzyl-6-
methylquinazoline propanehydrazonothioate 51 (K⁠Is, 251.1 and 237.5 nM).
(IV) Structure-activity relationship analysis for hCA IX inhibition indicated that 1) 6-
methylquinazolines 18 and 19 (K⁠Is, 17.9 and 20.1 nM) were more active against
hCA IX than compounds 12-17 (K⁠Is, 23.8-65.2 nM); 2) compounds 20-29 showed
high CAI selectivity toward hCA IX (K⁠Is, 15.2-29.2 nM) similar to that of AAZ
(KI, 25.0 nM); 3) 6-iodoquinazolines 26 and 27 (K⁠Is, 16.4 and 13.2 nM) were more
potent than other 6-substituted derivatives such as compounds 22-27 and 6,7-
dimethoxyquinazolines 28-29 (K⁠Is, 15.2-29.2 nM); 4) unsubstituted quinazoline
ethylsulfonamides 20, 21 and 6-substituted quinazoline ethylsulfonamide derivatives
containing a deactivating group such as compounds 22, 23, 26, and 27 (K⁠Is, 22.1,
18.4, 26.9, 15.2, 16.4, and 13.2 nM, respectively) were more active than the
corresponding sulfonamide derivatives 10-13, 16, and 17 (K⁠Is, 210.9, 262.4, 65.2,
28.3, 32.2, and 27.8 nM, respectively); on the other hand, 6,7-dimethoxyquinazoline
sulfonamides 14, 15, and 6-methylquinazoline sulfonamides 18, 19 (K⁠Is, 23.8, 24.2,
and 17.9, 20.1 nM, respectively) were more active than the corresponding
ethylsulfonamide derivatives 24, 25, 28, and 29 (K⁠Is, 28.6, 29.2, 24.3, and 24.6
nM); 5) anilides of benzensulfonamides 31 and 32 (K⁠Is, 31.6 and 29.2 nM) were
more potent than the corresponding anilides of benzylsulfonamides 35 and 36 (K⁠Is,

13
163.3 and 113.0 nM); 6) compounds 45-51 were highly selective CAIs (K⁠Is, 1.6-
23.1 nM) compared with AAZ (KI, 25.0 nM); 7) 3-phenyl unsubstituted quinazoline
propanehydrazonothioate 45 (KI, 1.8 nM) was more active than 3-phenyl 6-
substituted quinazoline propanehydrazonothioates 46, 48, and 49 (K⁠Is, 22.5, 12.3,
and 17.1 nM) whereas the CAI activity of 3-phenyl 6-methoxyquinazoline
propanehydrazonothioate 47 (KI, 1.6 nM) was similar to that of 45; 8) 3-phenyl
unsubstituted quinazoline propanehydrazonothioate
45
and
3-phenyl-6-
methylquinazoline propanehydrazonothioate 48 (K⁠Is, 1.8 and 12.3 nM) were more
active than 3-benzyl unsubstituted quinazoline propanehydrazonothioate 50 and 3-
benzyl-6-methylquinazoline propanehydrazonothioate 51 (K⁠Is, 20.3 and 23.1 nM).
Structure-activity relationship analysis for hCA XII inhibition indicated that 1) the
CAI activity of 6,7-dimethoxyquinazoline derivatives 14 and 15 (K⁠Is, 7.6 and 8.9
nM) was higher than that of compounds 12-13 and 16-19 (K⁠Is, 32.0-61.6 nM); 2)
acetamides such as compounds 20, 22, 24, 26, and 28 (K⁠Is, 8.8, 12.1, 15.2, 5.2, and
12.2 nM, respectively) were more effective than the corresponding propanamides 21,
23, 25, 27, and 29 (K⁠Is, 9.2, 40.6, 28.4, 19.0, and 16.6 nM, respectively); 3)
unsubstituted quinazoline derivatives such as compounds 20 and 21 (K⁠Is, 8.8 and
9.2 nM) were more active than the corresponding 6-substituted and 6,7-
dimethoxyquinazoline derivatives such as compounds 22-25 and 27-29 (K⁠Is, 12.1-
40.6 nM); 4) unsubstituted and 6-substituted quinazoline ethylslfonamide derivatives
such as compounds 20-22, 26-29 (K⁠Is, 8.8, 9.2, 12.1, 5.2, 19.0, 12.2, and 16.6 nM,
respectively) were more active than the corresponding sulfonamide derivatives 10-12,
16-19 (K⁠Is, 71.7, 75.5, 32.0, 44.8, 61.6, 50.1, and 42.5 nM, respectively); on the
(V)

14
other hand, 6-chloroquinazoline sulfonamide 13 and 6,7-dimethoxyquinazoline
sulfonamides 14 and 15 (K⁠Is, 34.6, 7.6 and 8.9 nM, respectively) were more active
than the corresponding ethylsulfonamide derivatives 23, 24, and 25 (K⁠Is, 40.6, 15.2,
and 28.4 nM, respectively); 5) propanamides 32 and 36 (K⁠Is, 46.8 and 58.8 nM)
were more active than acetamides 31 and 35 (K⁠Is, 73.0 and 90.5 nM); 6) 3-phenyl
unsubstituted quinazoline propanehydrazonothioate 45 (KI, 8.3 nM) was more active
than 3-phenyl 6-substituted quinazoline propanehydrazonothioates 46-49 (K⁠Is, 9.2-
149.4 nM); 7) 3-phenyl unsubstituted quinazoline propanehydrazonothioate 45 (KI,
8.3 nM) was more active than 3-benzyl unsubstituted quinazoline
propanehydrazonothioate 50 (KI, 51.1 nM) and 3-benzyl-6-methylquinazoline
propanehydrazonothioate 51 (KI, 23.8 nM) was more active than 3-phenyl-6-
methylquinazoline propanehydrazonothioate 48 (KI, 75.2 nM).
3. Conclusion
A new series of substituted mercaptoquinazolinones (10-29, 31, 32, 35, 36, and 45-51) was
synthesized and assessed for in vitro CA inhibition as compared to that of AAZ as reference
drug. Compounds 14, 15, 17, 19, 20, 21, 24, 25, 28, 29, 31, 45, 47, 49, and 51 showed strong
inhibitory activity against hCA I (K⁠Is, 39.4-353.8 nM) as compared with that of AAZ (KI,
250.0 nM). The hCA I isoform was moderately inhibited by compounds 12, 13, 16, 18, 22, 23,
26, 27, 32, 35, 36, 46, 48 and 50 with (K⁠Is, 421.9-700.5 nM) whereas compounds 10 and 11
showed weaker inhibitory activity with (K⁠Is, 3665.4 and 6472.2 nM, respectively). The hCA II
isoform was inhibited by compounds 12, 13, 14, 15, 20, 21, 24, 25, 27, 28, 29, 45, and 47 with
K values of 0.73-28.4 nM, which were comparable to that of AAZ, whereas compounds 16, 17,
⁠I
18, 19, 22, 23, and 26 showed moderate inhibitory action towards hCA II with K values of
⁠I

15
32.4-78.3 nM. Compounds 13-29, 31-32, and 45-51 exhibited strong hCA IX inhibitory activity
with KI values ranging between 1.6 and 32.2 nM, which were comparable to that of AAZ.
Compounds 14, 15, 20, 21, 26, 45, and 47 were effective inhibitors of hCA XII with K values
⁠I
in the range of 5.2-9.2 nM, which was similar to that of AAZ. Compounds 12, 13, 22, 23, 24, 25,
27, 28, 29, and 51 were less active hCA XII inhibitors with K values of 12.1-40.6 nM whereas
⁠I
compounds 10, 11, 16, 17, 18, 19, 31, 32, 35, 36, 46, 48, 49, and 50 were weak hCA XII
inhibitors (K⁠Is, 42.5-149.4 nM).
4. Materials and methods
4.1. Chemistry
Melting points were recorded on a Barnstead 9100 electrothermal melting point apparatus (UK).
IR spectra (KBr) were recorded on a FT-IR Perkin-Elmer spectrometer (Perkin Elmer Inc., MA).
13
Nuclear magnetic resonance (1H and C NMR) spectra were recorded with Bruker 500 or 700
MHz spectrometers (Zurich, Switzerland) using DMSO-d6 as the solvent. Microanalytical data
(C, H, and N) were obtained using a Perkin-Elmer 240 analyzer (Perkin Elmer Inc., MA) and
agreed with the proposed structures within ±0.4% of the theoretical values. Mass spectra were
recorded on a Varian TQ 320 GC/MS/MS mass spectrometer (Varian, Palo Alto, CA).
6-Substituted-2-mercapto-3-substituted-4(3H)-quinazolinones (1-5, 30 and 37-43) were prepared
by heating of anthranilic acid derivatives with appropriate benzylisothiocyanate or
phenylisothiocyanate in ethanol in the presence of triethylamine [31, 33, 34, 36, 37, 42, 43, 50,
51]. Anilides 6-9 and 33-34 were prepared by stirring an appropriate sulfonamide with 2-
chloroacetyl chloride or 2-chloropropanoyl chloride in dichloromethane in the presence of
triethylamine [45]. Previously reported protocols were followed to prepare compounds 31-32

16
(scheme 2; type F compounds), compounds 35-36 [45] (scheme 2; type G compounds), and
compound 44 [52].
General procedure for the synthesis of 2-[(3-benzyl-4(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenyl)anilides (10-19), (scheme 1; type D compounds).
A mixture of appropriate 2-mercapto-3-benzyl-4(3H)-quinazolinones (1-5) (2 mmol) and 2-
chloro-N-(4-sulfamoylphenyl)acetamide
(6)
(2
mmol)
or
2-chloro-N-(4-
sulfamoylphenyl)propanamides (7) (2 mmol) in 15 ml acetone containing anhydrous potassium
carbonate (3 mmol, 415 mg) was stirred at room temperature for 8-10 h. The reaction mixture
was filtered and the solvent was removed under reduced pressure; the recovered solid was dried
and recrystallized from ethanol, (scheme 1; type D compounds).
2-[(3-Benzyl-4(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)acetamide (10)
Yield, 96%; mp: > 350 °C; IR (KBr) νmax/cm-1 3397.0, 3271.49 (NH), 1682.0, 1666.0 (CO); 1H
NMR (500 MHz, DMSO-d6): 10.76 (s, 1H), 8.11 (d, 1H, J= 4.2 Hz), 7.79 (d, 5H, J= 7.0 Hz),
7.45 (d, 2H, J= 11.2 Hz), 7.36-7.30 (m, 5H), 7.27 (s, 2H), 5.37 (s, 2H), 4.23 (s, 2H); 13C NMR
(125 MHz, DMSO-d6): 166.75, 161.27, 157.00, 147.18, 142.33, 138.98, 136.04, 135.45,
129.09, 127.98, 127.37, 127.27, 127.14, 126.65, 126.24, 119.18, 119.13, 47.52, 37.50; m/z: 480
2-[(3-Benzyl-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)propanamide (11)

17
Yield, 95%; mp: 207-209 °C; IR (KBr) νmax/cm-1 3303.64 (br. NH) 1684.37, 1655.0 (CO); 1H
NMR (500 MHz, DMSO-d6):  8.10 (d, 1H, J= 10.5 Hz), 7.78 (dd, 4H, J= 13.3 & 12.6 Hz),
7.68-7.57 (m, 1H), 7.54-7.42 (m, 3H), 7.37-7.33 (m, 2H), 7.29 (d, 3H, J= 10.5 Hz), 7.24-7.21
(m, 1H), 5.33 (dd, 2H, J= 16.8 Hz), 4.76 (dd, 1H, J= 9.8 Hz), 1.60 (d, 3H, J= 9.8 Hz); 13C NMR
(125 MHz, DMSO-d6): 170.55, 161.24, 156.63, 147.23, 142.32, 139.17, 136.00, 135.45,
129.10, 128.99, 127.95, 127.24, 127.19, 127.12, 126.70, 126.25, 119.31, 119.24, 112.89, , 47.51,
47.19, , 17.82; m/z: 494
2-[(3-Benzyl-6-chloro-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)acetamide (12)
Yield, 95%; mp: 205-207 °C; IR (KBr) νmax/cm-1 3370.62, 3304.00, 3266.73 (NH), 1673.78
(CO); 1H NMR (500 MHz, DMSO-d6):  10.67 (s, 1H), 8.04 (d, 1H), 7.83 (dd, 1H, J= 2.0), 7.79-
7.75 (m, 4H), 7.47 (d, 1H, J= 9.0 Hz), 7.37-7.30 (m, 5H), 7.27, s, 2H), 5.36 (s, 2H), 4.22 (s, 2H);
13C NMR (125 MHz, DMSO-d6): 166.63, 160.36, 157.83, 145.89, 142.28, 139.01, 135.74,

18
135.57, 130.64, 129.10, 128.45, 128.04, 127.40, 127.26, 126.09, 120.43, 119.15, 47.73, 37.54;
m/z: 514, (M+2; 516).
2-[(3-Benzyl-6-chloro-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)propanamide
(13)
Yield, 93%; mp: 260-262 °C; IR (KBr) νmax/cm-1 3318.23, 3161.08 (NH), 1688.50, 1662.36
(CO); 1H NMR (500 MHz, DMSO-d6):  10.78 (s, 1H), 8.03 (d, 1H, J= 2.5 Hz), 7.84 (dd, 1H, J=
2.0 Hz), 7.77 (s, 4H), 7.52 (d, 1H, J= 8.5), 7.35 (s, 1H), 7.33 (s, 1H), 7.29-7.28 (m, 5H), 5.31 (s,
13
2H0, 4.74-4.70 (m, 1H), 1.60 (d, 3H, J= 7.5 Hz); C NMR (125 MHz, DMSO-d6): 170.42,
160.33, 157.42, 145.93, 142.18, 139.16, 135.67, 135.57, 130.73, 129.11, 128.43, 128.03, 127.27,
127.23, 126.08, 120.49, 119.34, 47.72, 47.24, 17.57; m/z: 528, (M+2; 530).
2-[(3-Benzyl-6,7-dimethoxy-4-(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenyl)acetamide
(14)
Yield, 92%; mp: >350 °C; IR (KBr) νmax/cm-1 3331.09, 3254.34, 3105.46 (NH), 1663.84,
1645.42 (CO); 1H NMR (500 MHz, DMSO-d6):  10.75 (s, 1H), 7.79 (s, 4H), 7.41-7.28 (m, 8H),

19
6.87 (s, 1H), 5.34 (s, 2H), 4.19 (s, 2H), 3.85 (s, 3H), 3.77 (s, 3H); 13C NMR (125 MHz, DMSO-
d6): 167.06, 160.65, 155.38, 154.89, 148.58, 143.48, 142.41, 138.98, 129.06, 127.94, 127.35,
127.28, 119.07, 112.01, 107.06, 106.10, 56.29, 56.19, 47.35, 37.4139; m/z: 540.
2-[(3-Benzyl-6,7-dimethoxy-4-(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenyl)propanamie
(15)
Yield, 92 %; mp: 155-157 °C; IR (KBr) νmax/cm-1 3413.43, 3312.0, 3214.0 (NH), 1685.71,
1
1654.27 (CO); H NMR (500 MHz, DMSO-d6):  8.34 (s, 1H), 7.89 (s, 1H), 7.72 (s, 2H), 7.67
(s, 2H), 7.59-7.31 (m, 8H), 5.37 (s, 2H), 4.77 (s, 1H), 3.81 (s, 3H), 3.77 (s, 3H) 3.36 (s, 2H), 2.79
(s, 2H), 1.60 (d, 3H, J= 6.5 Hz); m/z: 554.
2-[(3-Benzyl-6-iodo-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)acetamide (16)
Yield, 93%; mp: 219–220 °C; IR (KBr) νmax/cm-1 3435.67, 3261.88 (NH), 1678.24, 1654.44
(CO); 1H NMR (500 MHz, DMSO-d6):  10.81 (s, 1H), 8.35 (s, 1H), 8.04-7.33 (m, 13H), 5.34 (s,
13
2H), 4.23 (s, 2H); C NMR (125 MHz, DMSO-d6): 166.64, 160.02, 157.93, 146.42, 143.75,
142.29, 138.98, 135.76, 135.31, 129.11, 128.40, 128.04, 127.37, 127.27, 121.02, 119.14, 91.15,
47.69, 37.53; m/z: 605.

20
2-[(3-Benzyl-6-iodo-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)propanamide
(17)
Yield, 91 %; mp: 333-334 °C; IR (KBr) νmax/cm-1 3367.27, 3290.0, 3192.12 (NH), 1692.08,
1666.0 (CO); 1H NMR (500 MHz, DMSO-d6):  10.58 (s, 1H), 8.36 (d, 1H, J= 1.5 Hz), 8.10 (dd,
1H, J= 1.5 Hz), 7.77 (s, 4H), 7.35 (t, 3H, J= 5.0 & 5.5 Hz), 7.30 (s, 1H), 7.28 (d, 3H, J= 2.0 Hz),
13
7.27 (s, 1H), 5.30 (d, 2H, J= 5.5), 4.74-4.71 (m, 1H), 1.60 (d, 3H, J= 5.0 Hz); C NMR (125
MHz, DMSO-d6): 170.42, 159.99, 157.53, 146.47, 143.75, 142.22, 139.14, 135.71, 135.30,
129.11, 128.40, 128.01, 127.25, 127.22, 121.09, 119.32, 91.25, 47.68, 47.25, 17.79; m/z: 620.
2-[(3-Benzyl-6-methyl-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)acetamide (18)
Yield, 94%; mp: >350 °C; IR (KBr) νmax/cm-1 3413.37, 3328.04, 3238.67 (NH), 1685.57,
1670.79 (CO); 1H NMR (500 MHz, DMSO-d6):  10.76 (s, 1H), 7.90 (s, 1H), 7.78 (s, 4H), 7.60
13
(d, 1H, J= 5.5 Hz), 7.36-7.28 (m, 8H), 5.36 (s, 2H), 4.21 (s, 2H), 2.40 (s, 3H); C NMR (125
MHz, DMSO-d6): 166.80, 161.25, 155.87, 145.30, 142.34, 138.97, 136.68, 136.33, 136.12,
129.07, 127.95, 127.33, 127.26, 126.41, 126.14, 119.13, 118.92, 47.43, 37.45, 21.21; m/z: 494.

21
2-[(3-Benzyl-6-methyl-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenyl)propanamide
(19)
Yield, 94 %; mp: 252-254°C; IR (KBr) νmax/cm-1 3421.06, 3286.33 (NH), 1700.50, 1686.25
(CO); 1H NMR (500 MHz, DMSO-d6):  10.92 (d, 1H, J= 11.5), 7.90 (s, 1H), 7.79 (d, 4H, J= 6.5
Hz), 7.61 (d, 1H, J= 7.0), 7.42- 7.27 (m, 8H), 5.31 (d, 2H, J= 5.0 Hz), 4.75 (d, 1H, J= 5.5 Hz),
2.41 (s, 3H), 1.58 (d, 3H, J= 5.0 Hz); m/z: 508.
General procedure for the synthesis of 2-[(3-benzyl-4-(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenethyl)anilides (20-29), (scheme 1; type E compounds).
A mixture of appropriate 2-mercapto-3-benzyl-4(3H)-quinazolinones (1-5) (2 mmol) and 2-
chloro-N-(4-(2-sulfamoylethyl)phenyl)acetamide (2 mmol) (8) or 2-chloro-N-(4-(2-
sulfamoylethyl)phenyl)propanamide (2 mmol) (9) in 15 ml acetone containing anhydrous
potassium carbonate (3 mmol, 415 mg) was refluxed for 4-6 h. The reaction mixture was cooled
down and filtered; the solvent was removed under reduced pressure and the recovered solid was
dried and recrystallized from ethanol, (scheme 1; type E compounds).
2-[(3-Benzyl-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenethyl)acetamides (20)

22
Yield, 92%; mp: 173-175 °C; IR (KBr) νmax/cm-1 3399.76, 3279.85 (NH), 1673.94, 1651.41
(CO); 1H NMR (500 MHz, DMSO-d6):  8.39 (t, 1H, J= 4.9 & 5.6 Hz), 8.13 (d, 1H, J=7.7 Hz),
7.83 (t, 1H, J=7.0 & 7.7 Hz), 7.73 (d, 2H, J= 7.7 Hz), 7.51 (d, 1H, J= 8.4 Hz), 7.49 (t, 1H, J=7.0
& 7.7 Hz), 7.38 (d, 2H, J=7.7 Hz), 7.36 (d, 2H, J=8.4 Hz), 7.32 (s, 2H), 7.29 (d, 3H, J=7.7 Hz),
13
5.35 (s, 2H), 3.97 (s, 2H, J=6.3 & 7.0 Hz),), 3.36 (dd, 2H, ), 2.79 (t, 2H, J=7.0 Hz); C NMR
(125 MHz, DMSO-d6): 167.06, 161.35, 157.00, 147.23, 143.98, 142.53, 136.05, 135.43,
129.56, 129.09, 127.93, 127.26, 127.11, 126.62, 126.40, 126.16, 119.14, 36.31, 35.16, 47.39;
m/z: 508
2-[(3-Benzyl-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenethyl)propanamide (21)
Yield, 88%; mp: 198-199 °C; IR (KBr) νmax/cm-1 3421.76, 3290.98 (NH), 1687.00, 1654.58
(CO); 1H NMR (500 MHz, DMSO-d6):  8.45 (t, 1H, J= 5.6 Hz), 8.12 (dd, 1H, J= 1.4 Hz), 7.85-
7.83 (m, 1H), 7.72 (d, 2H, J= 8.4 Hz), 7.55 (d, 1H, J= 7.7 Hz), 7.50-7.48 (m, 1H), 7.37-7.34 (m,
4H), 7.31 (s, 2H), 7.28 (d, 1H, J= 7.7 Hz), 7.26 (d, 2H, J= 7.7 Hz), 5.34 (d, 1H, J= 16.8 Hz),
5.28 (d, 1H, J= 16.8 Hz), 4.55 (d, 1H, J= 7.0 Hz), 3.34-3.29 (m, 2H), 2.78 (t, 2H, J= 7.0 Hz),
13
1.47 (d, 3H, J= 7.0 Hz); C NMR (125 MHz, DMSO-d6): 170.73, 161.32, 156.72, 147.28,

23
143.91, 142.55, 136.03, 135.45, 129.59, 129.10, 127.90, 127.12, 126.67, 126.39, 126.10, 119.20,
35.05, 18.77, 47.33, 46.23, 40.47, 18.77; m/z: 522.1
2-[(3-Benzyl-6-chloro-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenethyl)acetamide
(22)
Yield, 89%; mp: 210-212 °C; IR (KBr) νmax/cm-1 3352.77, 3298.39 (NH), 1696.86, 1631.64
1
(CO); H NMR (500 MHz, DMSO-d6):  8.37 (t, 1H, J= 5.5 Hz), 8.05(d, 1H, J= 2.5 Hz), 7.86
(dd, 1H, J= 2.0 & 2.5 Hz), 7.73 (s, 1H), 7.72 (s, 1H), 7.52 (d, 1H, J= 9.0 Hz), 7.39-7.28 (m, 9H),
5.34 (s, 2H), 3.96 (s, 2H), 3.34 (t, 2H, J= 5.0 & 7.0 Hz), 2.97 (t, 2H, J= 7.0 & 7.5 Hz); 13C NMR
(125 MHz, DMSO-d6): 166.93, 160.42, 157.84, 145.94, 143.95, 142.55, 135.76, 135.502,
130.60, 129.54, 129.09, 128.61, 127.99, 127.31, 126.1514, 126.04, 120.39, 47.61, 40.49, 36.38,
35.14; m/z: 542; (M+2; 544).
2-[(3-Benzyl-6-chloro-4-(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenethyl)propanamide (23)

24
Yield, 87%; mp: 124-126 °C; IR (KBr) νmax/cm-1 3389, 3330.83, 3247.72 (NH), 1684.54,
1654.15 (CO); 1H NMR (500 MHz, DMSO-d6):  8.44 (s, 1H), 8.05 (d, 1H, J= 2.0 Hz), 8.85 (dd,
1H, J= 2.0 & 2.5 Hz), 7.75 (d, 1H, J= 8.0 Hz), 7.72 (s, 1H), 7.70 (S, 1H), 7.57 (d, 1H, J= 9.0
Hz), 7.40 (d, 1H, J= 7.0), 7.37 (s, 1H), 7.35 (d, 1H, J= 8.0 Hz), 7.33 (s, 1H), 7.30 (d, 2H, J= 5.5
Hz), 7.26 (s, 1H), 7.25 (s, 1H), 5.35-5.25 (m, 2H), 5.57-4.51 (m, 1H), 3.32-3.28 (m, 2H), 2.80-
13
2.77 (m, 2H), 1.47-1.45 (m, 3H); C NMR (125 MHz, DMSO-d6): 170.65, 160.40, 157.53,
145.99, 143.88, 142.55, 135.73, 135.49, 130.65, 129.65, 129.57, 129.09, 128.62, 127.96, 127.17,
126.11, 126.09, 126.03, 120.44, 47. 56, 46.34, 40.48, 35.03, 18.69; m/z: 556, (M+2; 558).
2-[(3-Benzyl-6,7-dimethoxy-4-(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenethyl)acetamide (24)
Yield, 90%; mp: 158-159 °C; IR (KBr) νmax/cm-1 3398.21, 3302.51 (NH), 1670.07, 1641.77
1
(CO); H NMR (500 MHz, DMSO-d6):  8.38 (s, 1H), 7.72 (d, 2H, J= 4.0 Hz), 7.44-7.27 (m,
10H), 7.03 (s, 1H), 5.34 (s, 2H), 3.96 (s, 2H), 3.90 (s, 3H), 3.88 (s, 3H), 3.35 (s, 2H), 2.80 (s,
2H); 13C NMR (125 MHz, DMSO-d6): 167.12, 160.75, 155.45, 154.88, 148.59, 143.94, 143.63,
142.53, 136.28, 129.54, 129.07, 127.88, 127.24, 126.15, 112.00, 107.27, 106.07, 56.45, 56.18,
47.20, 40.72, 36.24, 35.24; m/z: 568
2-[(3-Benzyl-6,7-dimethoxy-4-(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenethyl)propanamide (25)

25
Yield, 88%; mp: 255-257 °C; IR (KBr) νmax/cm-1 3421.03, 3181.47, 3121.62 (NH), 1717.96,
1686.68 (CO); 1H NMR (500 MHz, DMSO-d6):  8.43 (s, 1H), 7.70 (s, 3H), 7.60-7.30 (m, 9H),
6.95 (s, 1H), 5.66 (s, 2H), 4.54-4.45 (m, 1H), 3.85 (s, 3H), 3.82 (s, 3H), 3.35 (s, 2H), 2.78 (s,
2H), 1.47 (dd, 3H, J= 5.0 Hz); 13C NMR (125 MHz, DMSO-d6): 170.80, 159.35, 155.85,
155.47, 147.25, 143.88, 143.67, 142.54, 137.28, 135.58, 129.57, 129.07, 127.37, 127.10, 126.10,
108.45, 107.19, 98.25, 56.46, 56.21, 49.09, 40.46, 35.10, 29.53, 18.96; m/z: 582.
2-[(3-Benzyl-6-iodo-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenethyl)acetamide
(26)
Yield, 89%; mp: 210-212 °C; IR (KBr) νmax/cm-1 3355.02, 3303.79 (NH), 1694.13, 1654.06
1
(CO); H NMR (500 MHz, DMSO-d6):  8.37 (s, 2H), 8.11 (d, 1H, J=8.0 Hz), 7.74 (d, 2H, J=
7.0), 7.38 (d, 2H, J= 7.0 Hz), 7.34-7.29 (m, 8 H), 5.33 (s, 2H), 3.96 (s, 2H), 3.36 (s, 2H), 2.79 (s,
2H); 13C NMR (125 MHz, DMSO-d6): 166.92, 160.07, 157.95, 146.48, 143.95, 143.67, 142.55,
135.78, 135.28, 129.55, 129.08, 128.56, 127.97, 127.29, 126.16, 121.00, 91.05, 47.57, 40.71,
36.40, 35.16; m/z: 634.

26
2-[(3-Benzyl-6-iodo-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenethyl)propanamide
(27)
Yield, 87%; mp: 225-227 °C; IR (KBr) νmax/cm-1 3340.79, 3250.30, 3116.61 (NH), 1670.39,
1
1654.31 (CO); H NMR (500 MHz, DMSO-d6):  8.40 (d, 2H, J=22.0 Hz), 8.11 (d, 1H, J=7.0
Hz), 7.72 (d, 2H, J=7.5 Hz), 7.35-7.25 (m, 10H), 5.29 (d, 2H, J= 14.5 Hz), 4.52 (d, 1H, J= 6.5
Hz), 3.38 (s, 2H), 2.78 (s, 2H), 1.45 (d, 3H, J= 6.0 Hz); 13C NMR (125 MHz, DMSO-d6):
170.65, 160.05, 157.64, 146.53, 143.89, 143.69, 142.54, 135.74, 135.28, 129.58, 129.09,
128.57, 127.95, 127.14, 126.10, 121.06, 91.10, 47.53, 46.34, 40.47, 35.05, 18.70; m/z: 648.
2-[(3-Benzyl-6-methyl-4-(3H)-quinazolinon-2-yl)thio]-N-(4-sulfamoylphenethyl)acetamide
(28)
Yield, 88%; mp: 169-170 °C;IR (KBr) νmax/cm-1 3394.93, 3282.68 (NH), 1717.95 1654.33 (CO);
1H NMR (500 MHz, DMSO-d6):  2.36 (s, 1H), 7.91 (s, 1H), 7.73 (s, 2H), 7.65 (s, 1H), 7.42-
13
7.26 (m, 9H), 5.34 (s, 2H), 3.95 (s, 2H), 3.36 (s, 2H), 2.78 (s, 2H), 2.43 (s, 3H); C NMR (125
MHz, DMSO-d6): 167.09, 161.31, 155.90, 145.35, 143.97, 142.55, 136.67, 136.27, 136.14,

27
129.54, 129.06, 127.90, 127.23, 126.39, 126.29, 126.16, 118.90, 47.30, 40.71, 36.27, 35.17,
21.23; m/z: 522.
2-[(3-Benzyl-6-methyl-4-(3H)-quinazolinon-2-yl)thio]-N-(4-
sulfamoylphenethyl)propanamide (29)
Yield, 87%; mp: 160-162 °C; IR (KBr) νmax/cm-1 3336.28, 3258.37 (NH), 1677.23, 1654.10
(CO); 1H NMR (500 MHz, DMSO-d6):  8.41 (s, 1H), 7.91 (s, 1H), 7.71 (d, 2H, J= 6.5 Hz), 7.65
(d, 1H, J= 8.0 Hz), 7.46 (d, 1H, J= 8.5 Hz), 7.36-7.24 (m, 9H), 5.30 (dd, 2H, J= 16.0 & 16.5 Hz),
4.54 (d, 1H, J= 6.5 Hz), 3.35 (s, 2H), 2.78 (s, 2H), 2.44 (s, 3H), 1.47 (s, 3H); 13C NMR (125
MHz, DMSO-d6): 170.75, 161.28, 155.63, 145.40, 143.91, 142.56, 136.68, 136.34, 136.12,
129.56, 129.06, 127.86, 127.09, 126.39, 126.27, 126.10, 118.95, 47.26, 46.10, 40.50, 35.06,
21.23, 18.72; m/z: 536.
General procedure for the synthesis of 3-substituted-4-(3H)-quinazolinon-2-yl-2-oxo-N-(4-
sulfamoylphenyl)propanehydrazonothioate (45-51) (scheme 1; type H compounds).
A mixture of appropriate 3-substituted-2-mercapto-4(3H)-quinazolinone (37-43) (2 mmol) and
2-oxo-N-(4-sulfamoylphenyl)propanehydrazonoyl chloride (44) (2 mmol, 550 mg) in 15 ml
dioxane containing triethylamine (3 mmol, 303 mg) was refluxed for 4-5 h. The reaction mixture
was cooled down and the solvent was removed under reduced pressure; the recovered solid was

28
filtered, washed with water, dried, and recrystallized from ethanol (scheme 1; type H
compounds).
3-Phenyl-4- (3H)-quinazolinon-2-yl-2-oxo-N-(4-sulfamoylphenyl)propanehydrazonothioate
(45)
Yield, 85%; mp: 310-312 °C; IR (KBr) νmax/cm-1 3348.71, 3234.84 (NH), 1686.10, 1654.34
(CO); 1H NMR (700 MHz, DMSO-d6): 10.34 (s, 1H), 8.19 (d, 2H, J= 1.4 & 7.0 Hz), 7.94 (d,
2H, J= 7.0 Hz), 7.84 (d, 1H, J= 7.7 Hz), 7.62-7.57 (m, 1H), 7.54 (s, 2H), 7.35-7.30 (m, 2H), 7.28
(d, 2H, J= 4.9 Hz), 7.23 (t, 2H, J= 7.0 Hz), 7.02 (t, 1H, J= 6.3 &7.0 Hz), 2.58 (d, 3H, J= 8.4 Hz);
13C NMR (175 MHz, DMSO-d6): 189.95, 165.07, 157.13, 148.58, 148.34, 143.39, 140.86,
139.12, 132.93, 130.29, 129.21, 129.17, 128.73, 127.22, 125.37, 124.00, 119.60, 119.52, 25.50;
m/z: 493.
6-Chloro-3-phenyl-4(3H)-quinazolinon-2-yl-2-oxo-N-(4-
sulfamoylphenyl)propanehydrazonothioate (46)
Yield, 83%; mp: 333-335 °C; IR (KBr) νmax/cm-1 3290.00, 3166.99 (NH), 1705.07, 1689.03
(CO); 1H NMR (500 MHz, DMSO-d6): 10.39 (s, 1H), 8.15 (d, 2H, J= 9.0 Hz), 7.91 (d, 2H, J=

29
8.5 Hz), 7.82 (d, 1H, J= 2.0), 7.66 (dd, 1H, J= 2.5 Hz), 7.51 (s, 2H), 7.39 (d, 1H, J= 8.5 Hz),
7.32 (d, 2H, J= 7.5 Hz), 7.27 (d, 2H, J= 7.0 Hz), 7.05 (d, 1H, J= 6.0 Hz), 2.59 (s, 3H); 13C NMR
(125 MHz, DMSO-d6): 189.94, 163.79, 157.65, 149.01, 146.85, 143.15, 140.68, 139.14,
136.98, 132.45, 129.65, 129.24, 129.07, 127.20, 124.24, 124.06, 121.58, 119.76, 25.51; m/z:
527; (M+ 2; 529).
6-Methoxy-3-phenyl-4(3H)-quinazolinon-2-yl-2-oxo-n-(4-
sulfamoylphenyl)propanehydrazonothioate (47)
Yield, 82%; mp: 330-332 °C; IR (KBr) νmax/cm-1 3567.95, 3448.06 (NH), 1684.62, 1654.29
(CO); 1H NMR (700 MHz, DMSO-d6): 10.84 (s, 1H), 7.82 (d, 2H, J= 8.4 Hz), 7.58 (d, 2H, J=
8.4 Hz), 7.55 (s, 1H), 7.47 (t, 2H, J= 7.0 & 7.7 Hz), 7.40 (d, 2H, J= 7.7 Hz), 7.29 (s, 3H), 7.19 (d,
13
2H, J= 8.4 Hz), 3.87 (s, 3H), 2.59 (s, 3H); C NMR (175 MHz, DMSO-d6): 192.77, 161.51,
160.68, 154.75, 147.59, 145.59, 138.38, 135.48, 130.95, 130.13, 129.21, 127.80, 126.87, 126.68,
124.03, 121.05, 120.27, 115.34, 115.25, 114.31, 56.01, 26.30; m/z: 523.
6-Methyl-3-phenyl-4(3H)-quinazolinon-2-yl-2-oxo-N-(4-
sulfamoylphenyl)propanehydrazonothioate (48)