Aryl derivatives of 3H-1,2-benzoxathiepine 2,2-dioxide as carbonic anhydrase inhibitors

Article abstract of DOI:10.1080/14756366.2019.1695795

A new series of homosulfocoumarins (3H-1,2-benzoxathiepine 2,2-dioxides) possessing various substitution patterns and moieties in the 7, 8 or 9 position of the heterocylic ring were prepared by original procedures and investigated for the inhibition of four physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the human (h) hCA I, II, IX and XII. The 8-substituted homosulfocoumarins were the most effective hCA IX/XII inhibitors followed by the 7-substituted derivatives, whereas the substitution pattern in position 9 led to less effective binders for the transmembrane, tumour-associated isoforms IX/XII. The cytosolic isoforms hCA I and II were not inhibited by these compounds, similar to the sulfocoumarins/coumarins investigated earlier. As hCA IX and XII are validated anti-tumour targets, with one sulphonamide (SLC-0111) in Phase Ib/II clinical trials, finding derivatives with better selectivity for inhibiting the tumour-associated isoforms over the cytosolic ones, as the homosulfocoumarins reported here, is of crucial importance.

Full text of DOI:10.1080/14756366.2019.1695795

Journal of Enzyme Inhibition and Medicinal Chemistry
ISSN: 1475-6366 (Print) 1475-6374 (Online) Journal homepage: https://www.tandfonline.com/loi/ienz20
Aryl derivatives of 3H-1,2-benzoxathiepine 2,2-
dioxide as carbonic anhydrase inhibitors
Aleksandrs Pustenko, Alessio Nocentini, Anastasija Balašova, Ahmed
Alafeefy, Mikhail Krasavin, Raivis Žalubovskis & Claudiu T. Supuran
To cite this article: Aleksandrs Pustenko, Alessio Nocentini, Anastasija Balašova, Ahmed Alafeefy,
Mikhail Krasavin, Raivis Žalubovskis & Claudiu T. Supuran (2020) Aryl derivatives of 3H-1,2-
benzoxathiepine 2,2-dioxide as carbonic anhydrase inhibitors, Journal of Enzyme Inhibition and
Medicinal Chemistry, 35:1, 245-254, DOI: 10.1080/14756366.2019.1695795
To link to this article: https://doi.org/10.1080/14756366.2019.1695795
© 2019 The Author(s). Published by Informa
UK Limited, trading as Taylor & Francis
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JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY
2020, VOL. 35, NO. 1, 245–254
https://doi.org/10.1080/14756366.2019.1695795
RESEARCH PAPER
Aryl derivatives of 3H-1,2-benzoxathiepine 2,2-dioxide as carbonic
anhydrase inhibitors
c
a
d
e
Aleksandrs Pustenkoa,b, Alessio Nocentini , Anastasija Balasova , Ahmed Alafeefy , Mikhail Krasavin ,
ꢀ
Raivis Zalubovskis and Claudiu T. Supuranc
a,b
ꢀ
b
aLatvian Institute of Organic Synthesis, Riga, Latvia; Institute of Technology of Organic Chemistry, Faculty of Materials Science and Applied
c
Chemistry, Riga Technical University, Riga, Latvia; Dipartimento Neurofarba, Sezione di Scienze Farmaceutiche e Nutraceutiche, Universita degli
d
e
Studi di Firenze, Florence, Italy; Faculty of Pharmacy, University Technology MARA, UiTM, Bandar, Malaysia; Chemistry Department, Saint
Petersburg State University, Saint Petersburg, Russian Federation
ABSTRACT
ARTICLE HISTORY
Received 7 October 2019
Revised 13 November 2019
Accepted 14 November 2019
A new series of homosulfocoumarins (3H-1,2-benzoxathiepine 2,2-dioxides) possessing various substitution
patterns and moieties in the 7, 8 or 9 position of the heterocylic ring were prepared by original proce-
dures and investigated for the inhibition of four physiologically relevant carbonic anhydrase (CA, EC
4.2.1.1) isoforms, the human (h) hCA I, II, IX and XII. The 8-substituted homosulfocoumarins were the most
effective hCA IX/XII inhibitors followed by the 7-substituted derivatives, whereas the substitution pattern
in position 9 led to less effective binders for the transmembrane, tumour-associated isoforms IX/XII. The
cytosolic isoforms hCA I and II were not inhibited by these compounds, similar to the sulfocoumarins/cou-
marins investigated earlier. As hCA IX and XII are validated anti-tumour targets, with one sulphonamide
(SLC-0111) in Phase Ib/II clinical trials, finding derivatives with better selectivity for inhibiting the tumour-
associated isoforms over the cytosolic ones, as the homosulfocoumarins reported here, is of cru-
cial importance.
KEYWORDS
Carbonic anhydrase;
transmembrane isoforms;
sulfocoumarin; homosulfo-
coumarin; isoform-
selective inhibitor
1. Introduction
(3H-1,2-benzoxathiepine 2,2-dioxides)10. Considering the fact that
this last chemotype was only recently reported and rather poorly
investigated10, we report here a series of new aryl-3H-1,2-benzoxa-
thiepine 2,2-dioxides substituted in various positions of the het-
erocyclic ring, which have been designed in order to explore the
chemical space around this new CA inhibitory chemotype and to
see whether the presence of various moieties in position 7, 8 or 9
of the heterocyclic system maintains the desired enzyme inhibi-
tory activity and selectivity for the target isoforms.
Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes wide-
spread in nature, being encoded by at least eight different genetic
families, which have been identified in organisms all over the
phylogenetic tree1–3. By catalysing a crucial physiologic reaction,
by which CO2 is hydrated with the formation of a weak base
(bicarbonate) and a strong acid (hydronium ions), these enzymes
are involved in a multitude of physiologic processes, starting with
pH regulation and ending with metabolism1,3–6. As thus, CAs are
drug targets for decades, with their inhibitors having pharmaco-
logical applications in a multitude of fields1,3–5. The primary sul-
phonamides were discovered as CA inhibitors (CAIs) in the 40 s,
and most of the drugs that were launched in the next decades as
diuretics, antiepileptics, or antiglaucoma agents targeting CAs
belonged to this class of compounds1,3–5. Although highly effect-
ive as CAIs1, the sulphonamides generally indiscriminately inhibit
most a-CA isoforms present in mammals (at least 15 in humans,
and 16 in other vertebrates1) as well as CAs belonging to the
other genetic families (b-, c-, d-, f-, g-, h- and i-CAs)2–5 and for this
reason alternative CAI classes were searched for. In fact, in the last
10 years, a multitude of new chemotypes as well as novel CA
inhibition mechanisms were reported1,4,7–9, which highly enriched
our understanding of these enzymes and also allowed for obtain-
ing isoform-selective CAIs targeting all the mammalian iso-
2. Materials and methods
2.1. Chemistry
Reagents, starting materials and solvents were obtained from
commercial sources and used as received. Thin-layer chromatog-
raphy was performed on silica gel, spots were visualised with UV
light (254 and 365 nm). Melting points were determined on an
OptiMelt automated melting point system. IR spectra were
recorded on Shimadzu FTIR IR Prestige-21 spectrometer. NMR
spectra were recorded on Bruker Advance Neo (400 MHz) spec-
trometer with chemical shifts values (d) in ppm relative to TMS
using the residual DMSO-d6 signal (1H 2.50; 13 C 39.52) or CDCl3
signal (1H 7.26; 13 C 77.16) as an internal standard. High-resolution
mass spectra (HRMS) were recorded on a mass spectrometer with
forms4,7–9. Among the new such chemotypes, which also showed a Q-TOF micro mass analyser using the ESI technique. Elemental
the highest levels of isoform selectivity, were the coumarins9, the analyses were measured using Carlo Erba (EA1108) apparatus
sulfocoumarins7,8 and their congeners, homosulfocoumarins (Milan, Italy).
CONTACT Claudiu T. Supuran
claudiu.supuran@unifi.it
Neurofarba Department, University of Florence, Firenze 50121, Italy
ß 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.

246
A. PUSTENKO ET AL.
2-Hydroxy-5-iodobenzaldehyde (2)
(400 MHz, DMSO-d6) d ¼ 5.23 (dd, 1H, J ¼ 11.3, 1.4 Hz), 5.80 (dd,
1H, J ¼ 17.8, 1.4 Hz), 6.67 (d, 1H, J ¼ 8.6 Hz), 6.77–6.87 (m, 1H), 7.38
(dd, 1H, J ¼ 8.5, 2.3 Hz), 7.70 (d, 1H, J ¼ 2.3 Hz), 9.94 (s, 1H) ppm
13 C NMR (100 MHz, DMSO-d6) d ¼ 81.4, 115.1, 118.4, 126.9, 130.4,
134.4, 137.0, 154.6 ppm.
To a solution of salicylaldehyde (1) (8.73 mL, 81.9 mmol) in AcOH
(40 mL) iodine monochloride (4.92 mL, 98.3 mmol) was added11.
Reaction mixture was stirred 24 h at 40 ꢀC, then cooled to r.t.
EtOH (60 mL) was added and all volatiles were removed in vac-
uum. CH2Cl2 (60 mL) and water (100 mL) were added, the phases
were separated and the aqueous phase was extracted with CH2Cl2
(3 ꢁ 50 mL). The combined organic phases were washed with 10%
Na2S2O3 (1 ꢁ 60 mL), brine (1 ꢁ 60 mL), dried over Na2SO4, filtered
and concentrated. The residue was purified by column chromatog-
raphy on silica gel (PE/EtOAc 3:1), the crude product was re-crys-
tallised from EtOH to afford product 2 (17.1 g, 84%) as yellowish
3-Bromo-2-ethenylphenol (14)
Compound 14 was prepared according to the general procedure
from methyltriphenylphosphonium bromide (18.48 g; 51.7 mmol),
t-BuOK (7.15 g; 63.7 mmol) and 2-bromo-5-hydroxybenzaldehyde
(13) (4.00 g, 19.9 mmol) as yellowish solid (3.25 g; 82%). 1H NMR
(400 MHz, DMSO-d6) d ¼ 5.51 (dd, 1H, J ¼ 12.0, 2.4 Hz), 6.06 (dd,
1H, J ¼ 17.7, 2.4 Hz), 6.76 (dd, 1H, J ¼ 17.7, 11.9 Hz), 6.86–6.91
(m, 1H), 6.98 (t, 1H, J ¼ 8.0 Hz), 7.07 (dd, 1H, J ¼ 8.0, 1.2 Hz), 10.18
(s, 1H) ppm 13 C NMR (100 MHz, DMSO-d6) d ¼ 115.4, 120.9, 123.2,
123.4, 124.2, 129.1, 132.2, 157.1 ppm.
1
solid. H NMR (400 MHz, DMSO-d6) d ¼ 6.85 (d, 1H, J ¼ 8.6 Hz), 7.77
(dd, 1H, J ¼ 8.6, 2.4 Hz), 7.87 (d, 1H, J ¼ 2.4 Hz), 10.16 (s, 1H), 10.92
(s, 1H) ppm. 13 C NMR (100 MHz, DMSO-d6) d ¼ 81.4, 120.1, 124.6,
136.7, 144.1, 160.3, 189.8 ppm.
Prop-2-ene-1-sulphonyl chloride (4)
Compound was synthesised using previously described procedure
by our group10. To a solution of Na2SO3 (30.2 g; 0.24 mol) in water
(140 mL) ally bromide (17.4 mL; 0.20 mol) was added and the reac-
tion mixture was refluxed overnight. After cooling to room tem-
perature, reaction mixture was washed with Et2O (3 ꢁ 50 mL).
Aqueous phase was concentrated. Crude white solid was dried
under high vacuum at 100 ꢀC for 6 h. To the white solid at 0 ꢀC
POCl3 (120 mL) was added, and mixture was refluxed for 4 h. After
cooling to room temperature dry THF (60 mL) was added and
reaction mixture was vigorously stirred for 10 min and filtered.
Filter cake was suspended in dry THF (60 mL), suspension was vig-
orously stirred for 10 min and filtered. Filtrates were combined
and solvent was carefully driven off on rotary evaporator. Residue
was distilled in vacuum (10 mbar) and fraction with boiling point
38–42 ꢀC was collected, to give prop-2-ene-1-sulfonil chloride (4)
as colourless oil (18.6 g, 66%), which was used in further reactions
without additional purification.
5-Bromo-2-ethenylphenol (18)
Compound 18 was prepared according to the general procedure
from methyltriphenylphosphonium bromide (18.48 g; 51.7 mmol),
t-BuOK (7.15 g; 63.7 mmol) and 4-bromo-2-hydroxybenzaldehyde
(17) (4.00 g, 19.9 mmol) as yellowish solid (3.01 g; 76%)13. H NMR
1
(400 MHz, DMSO-d6) d ¼ 5.24 (dd, 1H, J ¼ 11.3, 1.6 Hz), 5.79 (dd,
1H, J ¼ 17.8, 1.6 Hz), 6.86 (dd, 1H, J ¼ 17.8, 11.3 Hz), 6.93–6.97
(m, 1H), 7.00 (d, 1H, J ¼ 2.0 Hz), 7.37 (d, 1H, J ¼ 8.3 Hz), 10.13 (s,
1H) ppm 13 C NMR (100 MHz, DMSO-d6) d ¼ 114.6, 118.3, 120.8,
122.0, 123.5, 128.0, 130.8, 155.7 ppm.
2-Bromo-6-ethenylphenol (27)
Compound 27 was prepared according to the general procedure
from methyltriphenylphosphonium bromide (18.48 g; 51.7 mmol),
t-BuOK (7.15 g; 63.7 mmol) and 3-bromo-2-hydroxybenzaldehyde
(26) (4.00 g, 19.9 mmol) as yellowish solid (3.17 g; 80%)14.
General procedure for the synthesis of ethenylphenoles (3, 14,
18, 27)
To a stirred solution of methyltriphenylphosphonium bromide
(2.60 eq) in dry THF (5 mL/1 mmol of methyltriphenylphosphonium
bromide), was added tBuOK (3.2 eq) in several portions over
20 min. Reaction mixture was stirred for 1 h at r.t. Corresponding
benzaldehyde (1 eq) was added and stirring continued at room
temperature for 24 h. Reaction mixture was diluted with CH2Cl2
1H NMR (400 MHz, DMSO-d6) d ¼ 5.29 (dd, 1H, J ¼ 11.2, 1.3 Hz),
5.78 (dd, 1H, J ¼ 17.6, 1.4 Hz), 6.80 (t, 1H, J ¼ 7.8 Hz), 7.02 (dd, 1H,
J ¼ 17.6, 11.2 Hz), 7.41–7.49 (m, 2H), 9.32 (s, 1H) ppm 13 C NMR
(100 MHz, DMSO-d6) d ¼ 112.2, 115.5, 121.3, 125.4, 127.5, 131.4,
(4 mL/1 mmol of methyltriphenylphosphonium bromide). Organic 132.1, 150.7 ppm.
layer was washed with water (2 ꢁ 20 mL) and brine (2 ꢁ 20 mL),
and dried over Na2SO4, filtered and concentrated. The crude prod-
uct was purified by column chromatography on silica gel
General procedure for diolefine (5, 15, 19, 28) synthesis
(PE/EtOAc 4:1).
To a stirred solution of corresponding ethenylphenol (3, 14, 18,
27) (1 eq) in CH2Cl2 (10 mL/1 mmol corresponding ethenylphenol)
at 0 ꢀC was added prop-2-ene-1-sulphonyl chloride (4) (1.39 eq)
and Et3N (1.4 eq). Reaction mixture was stirred overnight (20 h) at
room temperature. Water (30 mL) was added, reaction mixture
was extracted with EtOAc (3 ꢁ 40 mL), combined organic extracts
were washed with brine (2 ꢁ 40 mL), and dried over dried over
Na2SO4, filtered and concentrated. The crude product was purified
4-Iodo-2-ethenylphenol (3)
Compound 3 was prepared according to the general procedure
from methyltriphenylphosphonium bromide (14.98 g, 37.0 mmol),
t-BuOK (5.79 g, 51.6 mmol) and 2-hydroxy-5-iodobenzaldehyde (2)
(4.00 g, 16.1 mmol) as yellowish solid (3.29 g, 83%)12. 1H NMR by column chromatography on silica gel (EtOAc/PE 1:4).

JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY
247
4-Iodo-2-ethenylphenyl prop-2-ene-1-sulfonate (5)
0.80 Hz), 5.57–5.65 (m, 2H), 5.81 (dd, 1H, J ¼ 17.5, 0.8 Hz), 6.03–6.15
(m, 1H), 7.07–7.17 (m, 2H), 7.52–7.59 (m, 2H) ppm. 13 C NMR
(100 MHz, CDCl3) d ¼ 57.9, 117.7, 118.4, 123.9, 125.7, 126.0, 128.3,
130.9, 133.1, 135.1, 144.4 ppm. HRMS (ESI) [M þ H]þ: m/z calcd for
C11H12O3SBr: 302.9691. Found 302.9681.
Compound 5 was prepared according to the general procedure
from 4-iodo-2-ethenylphenol (3) (2.00 g; 8.13 mmol), prop-2-ene-1-
sulphonyl chloride (4) (1.11 mL; 10.57 mmol) and NEt3 (1.58 mL;
11.38 mmol) as yellowish oil (2.36 g; 83%). IR (film, cmꢂ1) ꢀmax
¼
1373 (S ¼ O), 1160 (S ¼ O). 1H NMR (400 MHz, DMSO-d6)
d ¼ 4.46–4.50 (m, 2H), 5.44–5.55 (m, 2H), 5.56–5.63 (m, 1H),
5.85–5.97 (m, 1H), 6.02 (d, 1H, J ¼ 17.6 Hz), 6.84 (dd, 1H, J ¼ 17.8,
11.2 Hz), 7.15 (d, 1H, J ¼ 8.6 Hz), 7.72 (dd, 1H, J ¼ 8.6, 2.2 Hz), 8.10
(d, 1H, J ¼ 2.2 Hz) ppm. 13 C NMR (100 MHz, DMSO-d6) d ¼ 54.9,
93.0, 119.0, 124.6, 125.0, 125.3, 128.4, 133.1, 134.9, 137.9,
145.7 ppm. HRMS (ESI) [M þ H]þ: m/z calcd for C11H12O3SI:
350.9552. Found 350.9542.
General method for 3H-1,2-benzoxathiepine 2,2-dioxide halogen
derivative (7, 20, 29) synthesis
To a solution of corresponding diolefine (5, 15, 19, 28) (1.0 eq) in
dry, degassed toluene (15 mL/1 mmol corresponding diolefine)
ruthenium catalyst 6 (5 mol %) was added. Reaction mixture was
bubbled with argon for 5 min and sealed, stirred at 70 ꢀC for 4 h.
After cooling to r.t. it was concentrated, and the crude product
was purified by column chromatography on silica gel (EtOAc/PE
1:4). Products were re-crystallised from EtOH.
3-Bromo-2-vinylphenyl prop-2-ene-1-sulfonate (15)
7-Iodo-3H-1,2-benzoxathiepine 2,2-dioxide (7)
Compound 15 was prepared according to the general procedure
from 3-bromo-2- ethenylphenol (14) (2.00 g; 10.05 mmol), prop-2-
ene-1-sulphonyl chloride (4) (1.37 mL; 13.06 mmol) and NEt3
Compound 7 was prepared according to the general procedure
from diolefine (5) (1.00 g; 2.86 mmol) and ruthenium catalyst 6
(0.14 g; 0.14 mmol) as yellowish solid (0.82 g; 89%). Mp 127–128 ꢀC.
IR (film, cmꢂ1) ꢀmax¼ 1370 (S ¼ O), 1164 (S ¼ O), 1155 (S ¼ O). 1H
NMR (400 MHz, DMSO-d6) d ¼ 4.52 (dd, 2H, J ¼ 5.8, 1.3 Hz),
5.97–6.04 (m, 1H), 6.82–6.87 (m, 1H), 7.14 (d, 1H, J ¼ 8.5 Hz), 7.79
(dd, 1H, J ¼ 8.5, 2.2 Hz), 7.88 (d, 1H, J ¼ 2.2 Hz) ppm. 13 C NMR
(100 MHz, DMSO-d6) d ¼ 51.6, 92.3, 121.5, 124.5, 129.8, 130.4,
138.7, 139.6, 146.7 ppm. Anal. Calcd for C9H7IO3S: C, 33.56; H, 2.19.
Found: C, 33.55; H, 2.21.
(1.96 mL; 14.07 mmol) as yellowish oil (2.01 g; 66%). IR (film, cmꢂ1
)
ꢀmax¼ 1368 (S ¼ O), 1174 (S ¼ O), 1160 (S ¼ O).
1H NMR (400 MHz, DMSO-d6) d ¼ 4.41 (dt, 2H, J ¼ 7.2, 1.0 Hz),
5.49–5.53 (m, 1H), 5.55–5.61 (m, 1H), 5.69–5.76 (m, 2H), 5.83–5.94
(m, 1H), 6.63 (dd, 1H, J ¼ 17.9, 11.7 Hz), 7.30–7.35 (m, 1H),
7.43–7.46 (m, 1H), 7.67 (dd, 1H, J ¼ 8.0, 1.1 Hz) ppm. 13 C NMR
(100 MHz, DMSO-d6) d ¼ 55.4, 122.4, 123.5, 123.7, 124.5, 125.2,
129.8, 130.6, 131.6, 131.9, 146.9 ppm. HRMS (ESI) [M þ H]þ: m/z
calcd for C11H12O3SBr: 302.9691. Found 302.9681.
8-Bromo-3H-1,2-benzoxathiepine 2,2-dioxide (20)
5-Bromo-2-vinylphenyl prop-2-ene-1-sulfonate (19)
Compound 20 was prepared according to the general procedure
from diolefine (19) (1.23 g; 4.06 mmol) and ruthenium catalyst 6
(0.19 g; 0.20 mmol) as white solid (1.0 g; 90%). Mp 144–145 ꢀC. IR
(film, cmꢂ1) ꢀmax¼ 1359 (S ¼ O), 1182 (S ¼ O), 1165 (S ¼ O). 1H
NMR (400 MHz, DMSO-d6) d ¼ 4.54 (dd, 2H, J ¼ 5.8, 1.0 Hz),
5.95–6.05 (m, 1H), 6.87 (d, 1H, J ¼ 11.4 Hz), 7.42–7.47 (m, 1H),
7.58–7.66 (m, 2H) ppm. 13 C NMR (100 MHz, DMSO-d6) d ¼ 51.9,
120.9, 122.0, 125.2, 127.5, 130.1, 130.3, 133.0, 147.1 ppm. Anal.
Calcd for C9H7BrO3S: C, 39.29; H, 2.56. Found: C, 39.28; H, 2.59.
Compound 19 was prepared according to the general procedure
from 5-bromo-2- ethenylphenol (18) (2.00 g; 10.05 mmol), prop-2-
ene-1-sulphonyl chloride (4) (1.37 mL; 13.06 mmol) and NEt3
(1.96 mL; 14.07 mmol) as yellowish oil (1.65 g; 54%). IR (film, cmꢂ1
)
ꢀmax¼ 1377 (S ¼ O), 1161 (S ¼ O). 1H NMR (400 MHz, DMSO-d6)
d ¼ 4.54 (dt, 2H, J ¼ 7.2, 1.0 Hz), 5.48 (dd, 1H, J ¼ 11.2, 0.8 Hz),
5.52–5.56 (m, 1H), 5.58–5.64 (m, 1H), 5.86–5.98 (m, 1H), 5.99 (dd,
1H, J ¼ 17.6, 0.9 Hz), 6.89 (dd, 1H, J ¼ 17.8, 11.2 Hz), 7.55–7.59 (m,
2H), 7.73–7.77 (m, 1H) ppm. 13 C NMR (100 MHz, DMSO-d6)
d ¼ 55.1, 118.4, 120.8, 124.5, 125.4, 125.6, 128.1, 128.7, 130.3,
130.5, 146.1 ppm. HRMS (ESI) [M þ H]þ: m/z calcd for C11H12O3SBr:
302.9691. Found 302.9684.
9-Bromo-3H-1,2-benzoxathiepine 2,2-dioxide (29)
Compound 29 was prepared according to the general procedure
from diolefine (28) (2.20 g; 7.26 mmol) and ruthenium catalyst 6
(0.34 g; 0.36 mmol) as yellowish solid (1.55 g; 78%). Mp 113–114 ꢀC.
2-Bromo-6-vinylphenyl prop-2-ene-1-sulfonate (28)
IR (film, cmꢂ1
)
ꢀmax¼
1364 (S ¼ O), 1177 (S ¼ O). 1H NMR
(400 MHz, CDCl3) d ¼ 4.10 (dd, 2H, J ¼ 6.0, 1.2 Hz), 5.95–6.03 (m,
1H), 6.82–6.87 (m, 1H), 7.18 (t, 1H, J ¼ 7.8 Hz), 7.24–7.28 (m, 1H),
7.66 (dd, 1H, J ¼ 7.9, 1.6 Hz) ppm. 13 C NMR (100 MHz, CDCl3)
d ¼ 51.8, 117.7, 120.1, 128.0, 130.0, 130.1, 132.2, 134.2, 144.9 ppm.
Anal. Calcd for C9H7BrO3S: C, 39.29; H, 2.56. Found: C, 39.28;
Compound 28 was prepared according to the general procedure
from 2-bromo-6-ethenylphenol (27) (2.00 g; 10.05 mmol), prop-2-
ene-1-sulphonyl chloride (4) (1.37 mL; 13.06 mmol) and NEt3
(1.96 mL; 14.07 mmol) as yellowish oil (2.62 g; 86%). IR (film, cmꢂ1
)
ꢀmax¼ 1367 (S ¼ O), 1179 (S ¼ O), 1165 (S ¼ O). 1H NMR (400 MHz,
CDCl3) d ¼ 4.31 (dt, 2H, J ¼ 7.2, 1.0 Hz), 5.45 (dd, 1H, J ¼ 11.0, H, 2.58.

248
A. PUSTENKO ET AL.
General method for 3H-1,2-benzoxathiepine 2,2-dioxide aril 13 C NMR (100 MHz, CDCl3) d ¼ 51.4, 116.1 (d, J ¼ 21.6 Hz), 119.9,
123.4, 128.6, 128.9, 129.0, 129.2, 129.3, 132.8, 135.6 (d, J ¼ 3.4 Hz),
derivative (8–12, 21–25 and 30–34) synthesis
139.6, 147.1, 163.0 (d, J ¼ 247.0 Hz) ppm. Anal. Calcd for
In a pressure tube corresponding 3H-1,2-benzoxathiepine 2,2-diox-
ide halogen derivative (7, 20, 29) (1.0 eq) was dissolved in dry C15H11FO3S: C, 62.06; H, 3.82. Found: C, 62.34; H, 3.83.
toluene (6 mL/1 mmol corresponding 3H-1,2-benzoxathiepine 2,2-
dioxide halogen derivative), degassed water was added (5% from
toluene volume), corresponding boronic acid (1.5 eq), K3PO4 (2.0
eq) and Pd(PPh3)4 (0.1 eq). Reaction mixture was bubbled with 7–(4-(Trifluoromethyl)phenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (11)
argon 5 min, tube was sealed and heated for 16 h at 100 ꢀC tem-
perature. Reaction mixture was cooled to r.t., filtered through cel-
lite was washed with EtOAc (40 mL). Mixture was evaporated and
Compound 11 was prepared according to the general procedure
crude product was purified by column chromatography on silica
from 7-iodo-3H-1,2-benzoxathiepine 2,2-dioxide (7) (0.20 g;
gel (EtOAc/PE 1:3). Products were re-crystallised from EtOH.
0.62 mmol)
(4-(trifluoromethyl)phenyl)boronic
acid
(0.18 g;
0.93 mmol), K3PO4 (0.26 g; 1.24 mmol) and Pd(PPh3)4 (72 mg;
0.062 mmol) as white solid (140 mg; 66%). Mp 166–168 ꢀC.
7- Phenyl-3H-1,2-benzoxathiepine 2,2-dioxide (8)
IR (film, cmꢂ1) ꢀmax¼1357 (S ¼ O), 1332 (S ¼ O), 1166 (S ¼ O).
1H NMR (400 MHz, DMSO-d6) d ¼ 4.56 (dd, 2H, J ¼ 5.8, 1.0 Hz),
6.00–6.08 (m, 1H), 6.99 (d, 1H, J ¼ 11.4 Hz), 7.47 (d, 1H, J ¼ 8.4 Hz),
7.81–7.86 (m, 3H), 7.88 (d, 1H, J ¼ 2.2 Hz), 7.94 (d, 2H, J ¼ 8.2 Hz)
ppm. 13 C NMR (100 MHz, DMSO-d6) d ¼ 51.8, 120.8, 123.0, 124.3
(q, J ¼ 273.0 Hz), 125.9 (q, J ¼ 3.7 Hz), 127.7, 128.3 (q, J ¼ 32.0 Hz),
128.6, 128.9, 130.3, 130.8, 137.4, 142.5, 146.9 ppm. Anal. Calcd for
C16H11F3O3S: C, 56.47; H, 3.26. Found: C, 56.46; H, 3.28.
Compound 8 was prepared according to the general procedure
from 7-iodo-3H-1,2-benzoxathiepine 2,2-dioxide (7) (0.20 g;
0.62 mmol) phenylboronic acid (0.11 g; 0.93 mmol), K3PO4 (0.26 g;
1.24 mmol) and Pd(PPh3)4 (72 mg; 0.062 mmol) as white solid
(95 mg; 56%). Mp 144–145 C. IR (film, cmꢂ1) ꢀmax¼1366 (S ¼ O),
1
1363 (S ¼ O), 1172 (S ¼ O), 1164 (S ¼ O). H NMR (400 MHz, CDCl3)
d ¼ 4.06 (dd, 2H, J ¼ 6.2, 0.8 Hz), 5.99–6.07 (m, 1H), 6.95 (d, 1H,
J ¼ 11.0 Hz), 7.38–7.43 (m, 2H), 7.44–7.52 (m, 3H), 7.54–7.58 (m,
2H), 7.62 (dd, 1H, J ¼ 8.4, 2.2 Hz) ppm. 13 C NMR (100 MHz, CDCl3)
d ¼ 51.4, 119.8, 123.3, 127.3, 128.1, 128.5, 129.1, 129.3, 129.4,
132.9, 139.4, 140.6, 147.1 ppm. Anal. Calcd for C15H12O3S: C, 66.16;
H, 4.44.Found: C, 66.06; H, 4.45.
7–(4-(Ethoxycarbonyl)phenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (12)
Compound 12 was prepared according to the general procedure
from 7-iodo-3H-1,2-benzoxathiepine 2,2-dioxide (7) (0.20 g;
7–(4-Methoxyphenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (9)
0.62 mmol)
(4-(ethoxycarbonyl)phenyl)boronic
acid
(0.18 g;
0.93 mmol), K3PO4 (0.26 g; 1.24 mmol) and Pd(PPh3)4 (72 mg;
0.062 mmol) as yellowish solid (96 mg; 44%). Mp 141–142 ꢀC. IR
(film, cmꢂ1) ꢀmax¼ 1701 (C ¼ O), 1380 (S ¼ O), 1184 (S ¼ O), 1170
(S ¼ O). 1H NMR (400 MHz, DMSO-d6) d ¼ 1.34 (t, 3H, J ¼ 7.1 Hz),
4.34 (q, 2H, J ¼ 7.1 Hz), 4.55 (dd, 2H, J ¼ 5.8, 1.2 Hz), 6.00–6.08 (m,
1H), 6.99 (d, 1H, J ¼ 11.5 Hz), 7.46 (d, 1H, J ¼ 8.5 Hz), 7.83 (dd, 1H,
J ¼ 8.5, 2.3 Hz), 7.85–7.90 (m, 3H), 8.03–8.08 (m, 2H) ppm. 13 C NMR
(100 MHz, DMSO-d6) d ¼ 14.2, 51.7, 60.8, 120.8, 123.0, 127.1, 128.6,
128.8, 129.2, 129.8, 130.1, 130.8, 137.7, 142.9, 146.9, 165.4 ppm.
Anal. Calcd for C18H16O5S: C, 62.78; H, 4.68. Found: C, 62.76;
H, 4.71.
Compound 9 was prepared according to the general procedure
from 7-iodo-3H-1,2-benzoxathiepine 2,2-dioxide (7) (0.20 g;
0.62 mmol) 4-methoxyphenylboronic acid (0.14 g; 0.93 mmol),
K3PO4 (0.26 g; 1.24 mmol) and Pd(PPh3)4 (72 mg; 0.062 mmol) as
yellowish solid (115 mg; 61%). Mp 162–163 C. IR (film, cmꢂ1) ꢀmax
¼
1395 (S ¼ O), 1375 (S ¼ O), 1179 (S ¼ O), 1156 (S ¼ O). 1H NMR
(400 MHz, DMSO-d6) d ¼ 3.80 (s, 3H), 4.50 (dd, 2H, J ¼ 5.8, 1.0 Hz),
5.98–6.06 (m, 1H), 6.97 (d, 1H, J ¼ 11.2 Hz), 7.02–7.07 (m, 2H), 7.38
(d, 1H, J ¼ 8.4 Hz), 7.62–7.67 (m, 2H), 7.69 (dd, 1H, J ¼ 8.4, 2.4 Hz),
7.73 (d, 1H, J ¼ 2.4 Hz) ppm. 13 C NMR (100 MHz, DMSO-d6)
d ¼ 51.6, 55.2, 114.5, 120.5, 122.7, 127.9, 128.0, 128.4, 129.0, 130.8,
131.2, 138.7, 145.8, 159.3 ppm. Anal. Calcd for C16H14O4S: C, 63.56;
H, 4.67. Found: C, 63.38; H, 4.68.
8-Phenyl-3H-1,2-benzoxathiepine 2,2-dioxide (21)
7–(4-Fluorophenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (10)
Compound 21 was prepared according to the general procedure
from 8-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (20) (0.25 g;
0.91 mmol) phenylboronic acid (0.17 g; 1.36 mmol), K3PO4 (0.39 g;
1.82 mmol) and Pd(PPh3)4 (105 mg; 0.091 mmol) as yellowish solid
(109 mg; 44%). Mp 103–104 ꢀC. IR (film, cmꢂ1) ꢀmax¼ 1376 (S ¼ O),
1177 (S ¼ O). 1H NMR (400 MHz, CDCl3) d ¼ 4.08 (dd, 2H, J ¼ 6.1,
1.2 Hz), 5.94–6.01 (m, 1H), 6.88–6.93 (m, 1H), 7.36–7.43 (m, 2H),
7.44–7.50 (m, 2H), 7.55–7.63 (m, 4H) ppm. 13 C KMR (100 MHz,
CDCl3) d ¼ 51.6, 119.2, 121.3, 125.7, 126.8, 127.2, 128.5, 129.2,
131.3, 132.5, 138.9, 144.0, 148.1 ppm. Anal. Calcd for C15H12O3S: C,
Compound 10 was prepared according to the general procedure
from 7-iodo-3H-1,2-benzoxathiepine 2,2-dioxide (7) (0.20 g;
0.62 mmol) (4-fluorophenyl)boronic acid (0.13 g; 0.93 mmol), K3PO4
(0.26 g; 1.24 mmol) and Pd(PPh3)4 (72 mg; 0.062 mmol) as white
solid (79 mg; 44%). Mp 117–118 ꢀC. IR (film, cmꢂ1) ꢀmax¼1373
(S ¼ O), 1181 (S ¼ O), 1168 (S ¼ O). 1H NMR (400 MHz, CDCl3)
d ¼ 4.06 (dd, 2H, J ¼ 6.2, 1.2 Hz), 5.99–6.06 (m, 1H), 6.93 (d, 1H,
J ¼ 11.0 Hz), 7.12–7.18 (m, 2H), 7.39 (d, 1H, J ¼ 8.4 Hz), 7.45 (d, 1H,
J ¼ 2.3 Hz), 7.49–7.55 (m, 2H), 7.57 (dd, 1H, J ¼ 8.4, 2.3 Hz) ppm. 66.16; H, 4.44. Found: C, 66.15; H, 4.46.

JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY
249
8–(4-Methoxyphenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (22)
1.2 Hz), 4.41 (q, 2H, J ¼ 7.1 Hz), 5.96–6.03 (m, 1H), 6.90 (d, 1H,
J ¼ 11.2 Hz), 7.39–7.43 (m, 1H), 7.57–7.62 (m, 2H), 7.65–7.70
(m, 2H), 8.11–8.16 (m, 2H) ppm. 13 C NMR (100 MHz, CDCl3)
d ¼ 14.5, 51.7, 61.3, 119.6, 121.5, 125.9, 127.1, 127.7, 130.4, 131.6,
132.3, 142.7, 143.0, 148.1, 166.3 ppm. Anal. Calcd for C18H16O5S: C,
62.78; H, 4.68. Found: C, 62.50; H, 4.70.
Compound 22 was prepared according to the general procedure
from 8-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (20) (0.25 g;
0.91 mmol) 4-methoxyphenylboronic acid (0.21 g; 1.36 mmol),
K3PO4 (0.39 g; 1.82 mmol) and Pd(PPh3)4 (105 mg; 0.091 mmol)ꢂa1s
yellowish solid (121 mg; 44%). Mp 142–143 ꢀC. IR (film, cm
)
9- Phenyl-3H-1,2-benzoxathiepine 2,2-dioxide (30)
ꢀmax¼ 1369 (S ¼ O), 1177 (S ¼ O), 1164 (S ¼ O). 1H NMR (400 MHz,
CDCl3) d ¼ 3.86 (s, 3H), 4.07 (dd, 2H, J ¼ 6.1, 1.1 Hz), 5.92–5.99 (m,
1H), 6.88 (d, 1H, J ¼ 11.1 Hz), 6.97–7.02 (m, 2H), 7.32–7.36 (m, 1H),
7.50–7.58 (m, 4H) ppm. 13 C NMR (100 MHz, CDCl3) d ¼ 51.6, 55.5,
114.6, 118.8, 120.6, 125.2, 126.1, 128.3, 131.3, 132.6, 143.6, 148.2,
160.1 ppm. Anal. Calcd for C16H14O4S: C, 63.56; H, 4.67. Found: C,
63.20; H, 4.69.
Compound 30 was prepared according to the general procedure
from 9-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (29) (0.25 g;
0.91 mmol) phenylboronic acid (0.17 g; 1.36 mmol), K3PO4 (0.39 g;
1.82 mmol) and Pd(PPh3)4 (105 mg; 0.091 mmol) as white solid
(104 mg; 42%). Mp 135–136 ꢀC. IR (film, cmꢂ1) ꢀmax¼ 1370 (S ¼ O),
1162 (S ¼ O). 1H NMR (400 MHz, CDCl3) d ¼ 4.08 (dd, 2H, J ¼ 5.8,
1.3 Hz), 5.87–5.94 (m, 1H), 6.85–6.90 (m, 1H), 7.29 (dd, 1H, J ¼ 7.6,
1.8 Hz), 7.35–7.42 (m, 2H), 7.43–7.49 (m, 3H), 7.51–7.55 (m, 2H)
ppm. 13 C KMR (100 MHz, CDCl3) d ¼ 52.1, 118.9, 127.1, 128.1,
128.5, 128.6, 129.6, 130.5, 132.1, 132.5, 136.3, 136.5, 144.7 ppm.
Anal. Calcd for C15H12O3S: C, 66.16; H, 4.44. Found: C, 66.15;
8–(4-Fluorophenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (23)
Compound 23 was prepared according to the general procedure
from 8-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (20) (0.25 g;
0.91 mmol) (4-fluorophenyl)boronic acid (0.19 g; 1.36 mmol), K3PO4
(0.39 g; 1.82 mmol) and Pd(PPh3)4 (105 mg; 0.091 mmol) as white H, 4.46.
solid (108 mg; 41%). Mp 111–112 ꢀC. IR (film, cmꢂ1) ꢀmax¼ 1371
(S ¼ O), 1168 (S ¼ O). 1H NMR (400 MHz, CDCl3) d ¼ 4.08 (dd, 2H,
9–(4-Methoxyphenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (31)
J ¼ 6.1, 1.2 Hz), 5.94–6.01 (m, 1H), 6.90 (d, 1H, J ¼ 11.0 Hz),
7.12–7.19 (m, 2H), 7.35–7.40 (m, 1H), 7.50–7.53 (m, 2H), 7.54–7.60
(m, 2H) ppm. 13 C NMR (100 MHz, CDCl3) d ¼ 51.7, 116.2 (d,
J ¼ 21.6 Hz), 119.3, 121.2, 125.6, 126.9, 128.9, 129.0, 131.5, 132.4,
135.0 (d, J ¼ 3.3 Hz), 142.9, 148.1, 163.2 (d, J ¼ 248.0 Hz) ppm. Anal.
Calcd for C15H11FO3S: C, 62.06; H, 3.82. Found: C, 62.04; H, 3.86.
Compound 31 was prepared according to the general procedure
from 9-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (29) (0.25 g;
0.91 mmol) 4-methoxyphenylboronic acid (0.21 g; 1.36 mmol),
K3PO4 (0.39 g; 1.82 mmol) and Pd(PPh3)4 (105 mg; 0.091 mmol) as
8–(4-(Trifluoromethyl)phenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (24)
white solid (110 mg; 40%). Mp 113–114 ꢀC. IR (film, cmꢂ1) ꢀmax
¼
1
1369 (S ¼ O), 1181 (S ¼ O), 1154 (S ¼ O). H NMR (400 MHz, CDCl3)
d ¼ 3.85 (s, 3H), 4.08 (dd, 2H, J ¼ 5.8, 1.3 Hz), 5.86–5.94 (m, 1H),
6.84–6.89 (m, 1H), 6.97–7.02 (m, 2H), 7.23–7.27 (m, 1H), 7.34 (t, 1H,
J ¼ 7.6 Hz), 7.42 (dd, 1H, J ¼ 7.6, 1.8 Hz), 7.45–7.50 (m, 2H) ppm.
13 C NMR (100 MHz, CDCl3) d ¼ 52.0, 55.4, 114.0, 118.9, 127.1,
128.6, 128.7, 130.1, 130.8, 132.0, 132.6, 136.2, 144.7, 159.5 ppm.
Anal. Calcd for C16H14O4S: C, 63.56; H, 4.67. Found: C, 63.58;
H, 4.70.
Compound 24 was prepared according to the general procedure
from 8-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (20) (0.25 g;
0.91 mmol) (4-(trifluoromethyl)phenyl)boronic acid (0.26 g;
1.36 mmol), K3PO4 (0.39 g; 1.82 mmol) and Pd(PPh3)4 (105 mg;
0.091 mmol) as white solid (142 mg; 46%). Mp 121–122 ꢀC. IR (film,
cmꢂ1) ꢀmax¼ 1366 (S ¼ O), 1324 (S ¼ O), 1172 (S ¼ O). 1H NMR
(400 MHz, CDCl3) d ¼ 4.11 (dd, 2H, J ¼ 6.1, 1.2 Hz), 5.97–6.04 (m,
1H), 6.90 (d, 1H, J ¼ 11.2 Hz), 7.40–7.44 (m, 1H), 7.55–7.60 (m, 2H),
7.70–7.75 (m, 4H) ppm. 13 C NMR (100 MHz, CDCl3) d ¼ 51.8, 119.7,
121.6, 124.2 (q, J ¼ 273.0 Hz), 125.9, 126.2 (q, J ¼ 3.8 Hz), 127.6,
127.8, 130.5 (q, J ¼ 32.9 Hz), 131.7, 132.2, 142.3, 142.4, 148.1 ppm.
Anal. Calcd for C16H11F3O3S: C, 56.47; H, 3.26. Found: C, 56.23;
H, 3.23.
9–(4-Fluorophenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (32)
Compound 32 was prepared according to the general procedure
from 9-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (29) (0.25 g;
0.91 mmol) (4-fluorophenyl)boronic acid (0.19 g; 1.36 mmol), K3PO4
(0.39 g; 1.82 mmol) and Pd(PPh3)4 (105 mg; 0.091 mmol) as white
solid (103 mg; 39%). Mp 130–131 ꢀC. IR (film, cmꢂ1) ꢀmax¼1370
(S ¼ O), 1154 (S ¼ O). 1H NMR (400 MHz, CDCl3) d ¼ 4.08 (dd, 2H,
J ¼ 5.8, 1.3 Hz), 5.88–5.95 (m, 1H), 6.85–6.90 (m, 1H), 7.10–7.18 (m,
2H), 7.30 (dd, 1H, J ¼ 7.5, 2.0 Hz), 7.37 (t, 1H, J ¼ 7.5 Hz), 7.41 (dd,
1H, J ¼ 7.5, 2.0 Hz), 7.47–7.53 (m, 2H) ppm. 13 C NMR (100 MHz,
CDCl3) d ¼ 52.1, 115.5 (d, J ¼ 21.6 Hz), 119.1, 127.2, 128.7, 130.6,
8–(4-(Ethoxycarbonyl)phenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (25)
Compound 25 was prepared according to the general procedure
from 8-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (20) (0.25 g;
0.91 mmol) (4-(ethoxycarbonyl)phenyl)boronic acid (0.26 g;
1.36 mmol), K3PO4 (0.39 g; 1.82 mmol) and Pd(PPh3)4 (105 mg;
0.091 mmol) as white solid (119 mg; 38%). Mp 151–152 ꢀC. IR (film,
cmꢂ1) ꢀmax¼ 1703 (C ¼ O), 1366 (S ¼ O), 1175 (S ¼ O). 1H NMR
(400 MHz, CDCl3) d ¼ 1.42 (t, 3H, J ¼ 7.1 Hz), 4.10 (dd, 2H, J ¼ 6.1, 131.3, 131.4, 132.0, 132.3 (d, J ¼ 3.3 Hz), 132.5, 135.6, 144.7, 162.8

250
A. PUSTENKO ET AL.
(d, J ¼ 247.0 Hz) ppm. Anal. Calcd for C15H11FO3S: C, 62.06; H, 3.82. 144.6, 166.5 ppm. Anal. Calcd for C18H16O5S: C, 62.78; H, 4.68.
Found: C, 62.05; H, 3.84.
Found: C, 62.28; H, 4.69.
2.2. CA inhibitory assay
9–(4-(Trifluoromethyl)phenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (33)
An Applied Photophysics stopped-flow instrument has been used for
assaying the CA catalysed CO2 hydration activity15. Phenol red (at a
concentration of 0.2 mM) was used as indicator, working at the
absorbance maximum of 557 nm, with 20 mM Hepes (pH 7.5) as buf-
fer and 20 mM Na2SO4 (for maintaining constant the ionic strength),
following the initial rates of the CA-catalysed CO2 hydration reaction
for a period of 10 ꢂ 100 s. The CO2 concentrations ranged from 1.7
to 17 mM for the determination of the kinetic parameters and inhib-
ition constants. For each inhibitor, at least six traces of the initial
5ꢂ 10% of the reaction have been used for determining the initial
velocity. The uncatalysed rates were determined in the same manner
and subtracted from the total observed rates. Stock solutions of
inhibitor (0.1 mM) were prepared in distilled ꢂ deionised water, and
dilutions up to 0.01 nM were done thereafter with the assay buffer.
Inhibitor and enzyme solutions were preincubated together for 6 h at
room temperature prior to assay in order to allow for the formation
of the E ꢂ I complex. The inhibition constants were obtained by non-
linear least-squares methods using PRISM 3 and the Cheng ꢂ Prusoff
equation, as reported earlier16–19, and represent the mean from at
least three different determinations. All CA isoforms were recombin-
Compound 33 was prepared according to the general procedure
from 9-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (29) (0.25 g;
0.91 mmol)
(4-(trifluoromethyl)phenyl)boronic
acid
(0.26 g;
1.36 mmol), K3PO4 (0.39 g; 1.82 mmol) and Pd(PPh3)4 (105 mg;
0.091 mmol) as white solid (136 mg; 44%). Mp 115–116 ꢀC.
IR (film, cmꢂ1) ꢀmax¼ 1333 (S ¼ O), 1166 (S ¼ O). 1H NMR
(400 MHz, CDCl3) d ¼ 4.10 (dd, 2H, J ¼ 5.8, 1.3 Hz), 5.90–5.97 (m,
1H), 6.86–6.91 (m, 1H), 7.35 (dd, 1H, J ¼ 7.0, 2.6 Hz), 7.38–7.45 (m,
2H), 7.62–7.67 (m, 2H), 7.70–7.74 (m, 2H) ppm. 13 C NMR (100 MHz,
CDCl3) d ¼ 52.2, 119.2, 124.5 (q, J ¼ 273.0 Hz), 125.5 (q, J ¼ 3.8 Hz),
127.3, 128.9, 130.0, 130.2 (q, J ¼ 32.0 Hz), 131.3, 131.9, 132.3, 135.2,
140.0 (q, J ¼ 1.5 Hz), 144.6 ppm. Anal. Calcd for C16H11F3O3S: C,
56.47; H, 3.26. Found: C, 56.21; H, 3.29.
9–(4-(Ethoxycarbonyl)phenyl)-3H-1,2-benzoxathiepine 2,2-dioxide (34)
ant ones obtained in-house as reported earlier19,20
.
3. Results and discussion
Compound 34 was prepared according to the general procedure
from 9-bromo-3H-1,2-benzoxathiepine 2,2-dioxide (29) (0.25 g;
3.1. Chemistry
0.91 mmol)
(4-(ethoxycarbonyl)phenyl)boronic
acid
(0.26 g;
The synthesis of desired compounds is partly based on the strat-
egy previously developed by our groups10. The synthesis of 7-aryl
3H-1,2-benzoxathiepine 2,2-dioxides starts with the iodination of
salicylaldehyde (1) by iodine monochloride and corresponding
iodo derivative 2 was isolated in good yield (Scheme 1)11. Under
Wittig reaction conditions aldehyde 2 was converted to olefin 3,
which was treated by sulphonyl chloride 4 thus providing bis-ole-
1.36 mmol), K3PO4 (0.39 g; 1.82 mmol) and Pd(PPh3)4 (105 mg;
0.091 mmol) as white solid (113 mg; 36%). Mp 105–106 ꢀC.
IR (film, cmꢂ1) ꢀmax¼ 1714 (C ¼ O), 1375 (S ¼ O), 1157 (S ¼ O).
1H NMR (400 MHz, CDCl3) d ¼ 1.41 (t, 3H, J ¼ 7.1 Hz), 4.08 (dd, 2H,
J ¼ 5.8, 1.1 Hz), 4.40 (q, 2H, J ¼ 7.1 Hz), 5.89–5.97 (m, 1H), 6.88 (d,
1H, J ¼ 11.4 Hz), 7.31–7.46 (m, 3H), 7.58–7.63 (m, 2H), 8.11–8.16 (m,
2H) ppm. 13 C NMR (100 MHz, CDCl3) d ¼ 14.5, 52.1, 61.1, 119.2, fin 5 in 83% yield. To obtain the key intermediate 7, the ring clos-
127.2, 128.8, 129.6, 129.7, 130.1, 131.1, 131.8, 132.4, 135.6, 140.9, ure in compound
5 was performed in olefin metathesis
Scheme 1. Reagents and conditions for the preparation of derivatives 8–12: (i) ICl, AcOH, 40ꢀC, 24 h, 84%; (ii) KOtBu, CH3P(C6H5)3Br, THF, RT, 18 h, 83%; (iii) NEt3,
CH2Cl2, 0 ꢀC to RT, 4 h, 83%; (iv) toluene, 70 ꢀC, 4 h, 89%; (v) Ar-B(OH)2, Pd(PPh3)4, K3PO4, toluene/H2O, 100 ꢀC, 16 h.

JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY
251
conditions, using Ru-catalyst 6. The key intermediate 7 was the treatment of aldehyde 26 with methyltriphenylphosphonium
reacted with a series of aryl boronic acids under Suzuki reaction bromide under Wittig reaction conditions (Scheme 4). The
obtained phenol 27 was reacted with sulphonyl chloride 4 and
ring closure of isolated 28 was successfully performed in Ru-cata-
lysed olefin metathesis conditions, providing bromide 29. Further
reaction of compound 9 with aryl boronic acids provided the
desired derivatives 30–34 in moderate yields.
conditions and the desired 7-aryl 3H-1,2-benzoxathiepine 2,2-diox-
ides 8–12 were isolated in acceptable yields (44–66%) (Scheme 1).
In an attempt to prepare 6-aryl 3H-1,2-benzoxathiepine 2,2-diox-
ides, the commercially available bromo salicylaldehyde 13 was first
converted to olefin 14 under Wittig reaction conditions, followed
by treatment with sulphonyl chloride 4, thus providing bis-olefin 15
for olefin metathesis ring closure reaction (Scheme 2). Utilisation of
the Ru-catalyst 6 as described above did not provide the formation
of the desired key intermediate 6-bromo 3H-1,2-benzoxathiepine
2,2-dioxide (16) even at prolonged reaction times. By doubling cata-
lyst 6 amount (10mol%) only traces of compound 16 were
observed after 40h. No product formation was observed also when
using Schrock and Schrock–Hoveyda Mo-catalysts. Probably olefin
metathesis ring closure reaction did not take place due to sterical
constraints due to the bulky Br atom at 3-positon of bis-olefin 15.
The synthesis of 8-bromo intermediate 20 was started from
commercially available aldehyde 17, when under Wittig reaction
conditions olefin 18 was obtained, which was thereafter treated
with sulphonyl chloride 4 and provided the bis-olefin 19 in good
yield (Scheme 3). Ru-catalysed olefin metathesis afforded the key
intermediate 20 which in turn, by reaction with a series of aryl
3.2. Carbonic anhydrase inhibition
The obtained homosulfocoumarins 7–34 were investigated for
their CA inhibitory properties by using a stopped-flow CO2
hydrase assay15 and four human CA isoforms (hCA I, II, IX and XII)
known to be drug targets1 (Table 1).
The following structure-activity relationship (SAR) can be
observed from the inhibition data of Table 1.
(i) as the previously reported homosulfocoumarins10 and similar
to sulfocoumarins7–9, also the derivatives reported here did not
significantly inhibit the cytosolic isoforms hCA I and II, unlike the
sulphonamide acetazolamide (used as standard CAI), which has a
very good affinity (in the nanomolar range) for hCA II and a
micromolar one for hCA I (Table 1).
(ii) the transmembrane, tumour-associated isoforms hCA IX and
boronic acids under Suzuki reaction condition, provided the XII were effectively inhibited by derivatives 7–29 reported here (in
desired compounds 21–25.
the low – medium nanomolar arneg) and were poorly inhibited, in
The same strategy was successfully utilised for the synthesis of the micromolar range by the 9-substituted-homosulfocoumarins
a series of 9-aryl 3H-1,2-benzoxathiepine 2,2-dioxides starting by 30–34 (KIs in the range of 16.4–60.9 mM against hCA IX and >100 mM
Scheme 2. Reagents and conditions: (i) KOtBu, CH3P(C6H5)3Br, THF, RT, 18 h, 82%; (ii) 4, NEt3, CH2Cl2, 0 ꢀC to RT, 4 h, 66%; (iii) a) 6 (5 mol% and 10 mol%), toluene,
70 ꢀC, 40h, 0%; b) Schrock catalyst [Mo] (10mol%), toluene, 70 ꢀC, 16 h, 0%; c) Schrock–Hoveyda [Mo] (10mol%), toluene, 70 ꢀC, 16 h, 0%;
Scheme 3. Reagents and conditions: (i) KOtBu, CH3P(C6H5)3Br, THF, RT, 18 h, 76%; (ii) 4, NEt3, CH2Cl2, 0 ꢀC to RT, 4 h, 54%; (iii) 6, toluene, 70 ꢀC, 4 h, 90%; (iv) Ar-
B(OH)2, Pd(PPh3)4, K3PO4, toluene/H2O, 100 ꢀC, 16h.

252
A. PUSTENKO ET AL.
Scheme 4. Reagents and conditions: (i) KOtBu, CH3P(C6H5)3Br, THF, RT, 18 h, 80%; (ii) 4, NEt3, CH2Cl2, 0 ꢀC to RT, 4 h, 86%; (iii) 6, toluene, 70 ꢀC, 4 h, 78%; (iv) Ar-
B(OH)2, Pd(PPh3)4, K3PO4, toluene/H2O, 100 ꢀC, 16h.
2934 nM against hCA XII. On the contrary, for the 8- substituted
homosulfocoumarins, the KIs were in the range of 44.0 – 104.8 nM
against hCA IX and in the range of 77.9 – 473.2 nM for hCA XII
(Table 1). The 8–(4-trifluoromethyl)phenyl-substituted homosulfocou-
marin 24 was the most effective hCA IX inhibitor (potency in the
same range as AAZ), whereas the corresponding 4-fluorophenyl
derivative 23 was the best hCA XII inhibitor in the new series of com-
pounds investigated here but it was an order of magnitude less
effective compared to acetazolamide.
Table 1. Inhibition data of human CA isoforms CA I, II, IX and XII with 3H-1,2-
benzoxathiepines 2,2-dioxide 7–34 using AAZ as a standard drug.
ꢃ
KI (nM)
Cmpd 7 / 8 / 9
R
CA I
CA II
CA IX
66.2
CA XII
455.5
7
8
9
7
7
7
7
7
7
8
8
8
8
8
8
9
9
9
9
9
9
–
I
H
OCH3
F
>100 mM >100 mM
>100 mM >100 mM 654.8
>100 mM >100 mM 407.6
>100 mM >100 mM 330.8
>100 mM >100 mM 221.4
1376
2934
890.5
4017
2398
132.9
473.2
168.6
77.9
4. Conclusions
10
11
12
20
21
22
23
24
25
29
30
31
32
33
34
AAZ
CF3
A new series of homosulfocoumarins (3H-1,2-benzoxathiepine 2,2-
dioxides) possessing various moieties in the 7, 8 or 9 position of
the heterocylic ring were prepared by original procedures and
investigated for the inhibition of four physiologically relevant CA
isoforms, hCA I, II, IX and XII. The 8-substituted homosulfocoumarins
were the most effective hCA IX/XII inhibitors followed by the 7-sub-
stituted derivatives, whereas the substitution pattern in position 9
led to less effective inhibitors for these transmembrane, tumour-
associated isoforms. The cytosolic isoforms hCA I and II were not
inhibited by these compounds, similar to the sulfocoumarins/cou-
marins investigated earlier. As hCA IX and XII are validated anti-
tumour targets5, with one sulphonamide (SLC-0111) in Phase Ib/II
clinical trials, finding derivatives with a better selectivity for inhibit-
ing the tumour-associated isoforms over the cytosolic ones, as the
homosulfocoumarins reported here, is of crucial importance.
CO2CH2CH3 >100 mM >100 mM 620.8
Br
H
OCH3
F
>100 mM >100 mM
>100 mM >100 mM 104.8
>100 mM >100 mM
>100 mM >100 mM
>100 mM >100 mM
47.5
63.1
95.2
44.0
79.8
CF3
247.8
289.3
3824
CO2CH2CH3 >100 mM >100 mM
Br
H
OCH3
F
>100 mM >100 mM 754.8
>100 mM >100 mM
>100 mM >100 mM
>100 mM >100 mM
>100 mM >100 mM
21.1 mM >100 mM
60.9 mM >100 mM
33.7 mM >100 mM
47.1 mM >100 mM
16.4 mM >100 mM
CF3
CO2CH2CH3 >100 mM >100 mM
–
250
12
25
5.7
ꢃMean from three different assays, by a stopped flow technique (errors were in
the range of 5–10% of the reported values).
against hCA XII). Thus, although weak inhibitors, these sulfocoumarins
are anyhow highly selective for the inhibition of hCA IX, whereas
their activity against hCA I, II and XII is absent (Table 1). As already
anticipated above, the most important factors associated with CA IX/
XII inhibitory activity are the position and the nature of the moieties
present on the six-membered ring of the homosulfocoumarin.
Indeed, for 9-substituted derivatives, the presence of bulky, substi-
tuted aryls as in 30–34 leads to low activity, as mentioned above.
Only the 9-bromo-derivative 29 had a medium potency inhibitory
action against the two isoforms, with KIs in the range of 754.8 –
3824 nM. On the contrary, the 8-substituted derivatives 20–25
showed a much better inhibitory power against both isoforms, being
generally more potent than the corresponding 7-substituted deriva-
tives 7–12. Indeed, for the 7-substituted homosulfocoumarins the KIs
were in the range of 66.2 – 620.8 nM against hCA IX and of 455.5 –
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by ERA.Net RUS plus joint programme pro-
ject THIOREDIN (State Education Development Agency of Republic of
Latvia) [grant number RUS_ST2017-309] and the Russian Foundation
for Basic Research [grant number 18–515-76001].
ORCID
Claudiu T. Supuran
http://orcid.org/0000-0003-4262-0323

JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY
253
inhibitors of tumor-associated carbonic anhydrases. J Med
Chem 2013;56:293–300.
References
1. (a) Supuran CT. Carbonic anhydrases: novel therapeutic
applications for inhibitors and activators. Nature Rev Drug
Discov 2008;7:168–81.(b) Alterio V, Di Fiore A, D’Ambrosio K,
et al. Multiple binding modes of inhibitors to carbonic anhy-
drases: how to design specific drugs targeting 15 different
isoforms? Chem Rev 2012;112:4421–68.(c) Supuran CT.
Structure and function of carbonic anhydrases. Biochem J
2016;473:2023–32.
2. (a) Xu Y, Feng L, Jeffrey PD, et al. Structure and metal
exchange in the cadmium carbonic anhydrase of marine
diatoms. Nature 2008;452:56–61.(b) Del Prete S, Vullo D,
Fisher GM, et al. Discovery of a new family of carbonic anhy-
drases in the malaria pathogen Plasmodium falciparum – the
g-carbonic anhydrases. Bioorg Med Chem Lett 2014;24:
4389–96.(c) Jensen EL, Clement R, Kosta A, et al. A new
widespread subclass of carbonic anhydrase in marine phyto-
plankton. ISME J 2019;13:2094–106.
8. (a) Tanc M, Carta F, Bozdag M, et al. 7-Substituted-sulfocou-
marins are isoform-selective, potent carbonic anhydrase II
inhibitors. Bioorg Med Chem 2013;21:4502–10.(b) Nocentini
A, Ceruso M, Carta F, Supuran CT. 7-Aryl-triazolyl-substituted
sulfocoumarins are potent, selective inhibitors of the tumor-
associated carbonic anhydrase IX and XII. J Enzyme Inhib
Med Chem 2016;31:1226–33.(c) Grandane A, Tanc M,
Mannelli LDC, et al. Substituted sulfocoumarins are selective
carbonic anhdydrase IX and XII inhibitors with significant
cytotoxicity against colorectal cancer cells. J. Med. Chem
2015;58:3975–83.
9. (a) Maresca A, Temperini C, Vu H, et al. Non-zinc mediated
inhibition of carbonic anhydrases: coumarins are a new class
of suicide inhibitors. J Am Chem Soc 2009;131:3057–62.(b)
Maresca A, Temperini C, Pochet L, et al. Deciphering the
mechanism of carbonic anhydrase inhibition with coumarins
and thiocoumarins.
J
Med Chem 2010;53:335–44.(c)
3. (a) Capasso C, Supuran CT. Anti-infective carbonic anhydrase
inhibitors: a patent and literature review. Expert Opin Ther
Pat 2013;23:693–704.(b) Capasso C, Supuran CT. An overview
of the alpha-, beta- and gamma-carbonic anhydrases from
bacteria: can bacterial carbonic anhydrases shed new light
on evolution of bacteria? J Enzyme Inhib Med Chem 2015;
30:325–32.(c) Capasso C, Supuran CT. Bacterial, fungal and
protozoan carbonic anhydrases as drug targets. Expert Opin
Ther Targets 2015;19:1689–704.(d) Supuran CT, Capasso C.
Biomedical applications of prokaryotic carbonic anhydrases.
Expert Opin Ther Pat 2018;28:745–54.
Temperini C, Innocenti A, Scozzafava A, et al. The coumarin-
binding site in carbonic anhydrase accommodates structur-
ally diverse inhibitors: the antiepileptic lacosamide as an
example. J Med Chem 2010;53:850–4.(d) Touisni N, Maresca
A, McDonald PC, et al. Glycosylcoumarin carbonic anhydrase
IX and XII inhibitors strongly attenuate the growth of pri-
mary breast tumors. J Med Chem 2011;54:8271–7.
ꢀ
10. Pustenko A, Stepanovs D, Zalubovskis R, et al. 3H-1,2-ben-
zoxathiepine 2,2-dioxides: a new class of isoform-selective
carbonic anhydrase inhibitors. J Enzyme Inhib Med Chem
2017;32:767–75.
4. (a) Supuran CT. How many carbonic anhydrase inhibition
mechanisms exist? J Enzyme Inhib Med Chem 2016;31:
345–60.(b) Nocentini A, Supuran CT. Advances in the struc-
tural annotation of human carbonic anhydrases and impact
on future drug discovery. Expert Opin Drug Discov 2019;14:
1175–97.(c) Supuran CT. Advances in structure-based drug
discovery of carbonic anhydrase inhibitors. Expert Opin
Drug Discov 2017;12:61–88.(d) De Simone G, Supuran CT.
(In)organic anions as carbonic anhydrase inhibitors. J Inorg
Biochem 2012;111:117–29.
5. (a) Supuran CT. Carbonic anhydrase inhibitors as emerging
agents for the treatment and imaging of hypoxic tumors.
Expert Opin Investig Drugs 2018;27:963–70.(b) Supuran CT.
Carbonic anhydrase inhibitors and their potential in a range
of therapeutic areas. Expert Opin Ther Pat 2018;28:
709–12.(c) Supuran CT. Applications of carbonic anhydrases
inhibitors in renal and central nervous system diseases.
Expert Opin Ther Pat 2018; 28:713–21.(d) Neri D, Supuran
CT. Interfering with pH regulation in tumours as a thera-
peutic strategy. Nat Rev Drug Discov 2011;10:767–77.(e)
Supuran CT, Alterio V, Di Fiore A, et al. Inhibition of carbonic
anhydrase IX targets primary tumors, metastases, and cancer
stem cells: three for the price of one. Med Res Rev 2018;38:
1799–836.
11. Yin H, Zhang B, Yu H, et al. Two-photon fluorescent probes
for biological Mg2þ detection based on 7-substituted cou-
marin. J Org Chem 2015;80:4306–12.
12. Gillis EP, Burke MD. A simple and modular strategy for small
molecule synthesis: iterative Suzuki–Miyaura coupling of B-
protected haloboronic acid building blocks. J Am Chem Soc
2007;129:6716–7.
13. Seoane A, Casanova N, Quinones N, et al. Straightforward
assembly of benzoxepines by means of a rhodium(III)-cata-
lyzed C-H functionalization of o-vinylphenols. J Am Chem
Soc 2014;136:834–7.
14. Hoveyda HR, Marsault E, Gagnon R, et al. Optimization of the
potency and pharmacokinetic properties of a macrocyclic ghre-
lin receptor agonist (Part I): development of ulimorelin (TZP-
101) from hit to clinic. J Med Chem 2011;54:8305–20.
15. Khalifah RG. The carbon dioxide hydration activity of car-
bonic anhydrase. J Biol Chem 1971;246:2561–73.
16. (a) Nocentini A, Bua S, Del Prete S, et al. Malassezia globosa:
activity and modeling studies. ChemMedChem 2018;13:
816–23.(b) D’Ascenzio M, Guglielmi P, Carradori S, et al.
Open saccharin-based secondary sulfonamides as potent
and selective inhibitors of cancer-related carbonic anhydrase
IX and XII isoforms. J Enzyme Inhib Med Chem 2017;32:
51–9.(c) Nocentini A, Ceruso M, Bua S, et al. Discovery of
b-adrenergic receptors blocker-carbonic anhydrase inhibitor
hybrids for multitargeted antiglaucoma therapy. J Med
6. (a) Supuran CT. Carbonic anhydrases and metabolism.
Metabolites 2018;8:25.(b) Supuran CT. Carbonic anhydrase
inhibition and the management of hypoxic tumors.
Metabolites 2017;7:E48.(c) Da’dara AA, Angeli A, Ferraroni M,
et al. Crystal structure and chemical inhibition of essential
schistosome host-interactive virulence factor carbonic anhy-
drase SmCA. Commun Biol 2019;2:333.
€
Chem 2018;61:5380–94.(d) Kohler K, Hillebrecht A, Schulze
Wischeler J, et al. Saccharin inhibits carbonic anhydrases:
possible explanation for its unpleasant metallic aftertaste.
Angew Chem Int Ed Engl 2007;46:7697–9.
17. (a) Vermelho AB, da Silva Cardoso V, Ricci Junior E, et al.
Nanoemulsions of sulfonamide carbonic anhydrase inhibi-
tors strongly inhibit the growth of Trypanosoma cruzi. J
7. Tars K, Vullo D, Kazaks A, et al. Sulfocoumarins (1,2-benzoxa-
thiine 2,2-dioxides): a class of potent and isoform-selective

254
A. PUSTENKO ET AL.
Enzyme Inhib Med Chem 2018;33:139–46.(b) Nocentini A,
Carta F, Tanc M, et al. Deciphering the mechanism of human
carbonic anhydrases inhibition with sulfocoumarins: compu-
tational and experimental studies. Chemistry 2018;24:
7840–4.(c) Awadallah FM, Bua S, Mahmoud WR, et al.
Inhibition studies on a panel of human carbonic anhydrases
with N1-substituted secondary sulfonamides incorporating
thiazolinone or imidazolone-indole tails. J Enzyme Inhib
Med Chem 2018;33:629–38.
binding mechanisms. J Enzyme Inhib Med Chem 2018;33:
1453–9.(b) Nocentini A, Trallori E, Singh S, et al. 4-Hydroxy-
3-nitro-5-ureido-benzenesulfonamides selectively target the
tumor-associated carbonic anhydrase isoforms IX and XII
showing hypoxia-enhanced antiproliferative profiles. J Med
Chem 2018;61:10860–74.(c) Chohan ZH, Munawar A,
Supuran CT. Transition metal ion complexes of Schiff bases.
Synthesis, characterization and antibacterial properties. Met
€
Based Drugs 2001;8:137–43.(d) Ozturk Sarikaya SB, Topal F,
18. (a) Bua S, Bozdag M, Del Prete S, et al. Mono- and di-thio-
carbamate inhibition studies of the d-carbonic anhydrase
TweCAd from the marine diatom Thalassiosira weissflogii. J
Enzyme Inhib Med Chem 2018;33:707–13.(b) Ferraroni M,
Gaspari R, Scozzafava A, et al. Dioxygen, an unexpected car-
bonic anhydrase ligand. J Enzyme Inhib Med Chem 2018;33:
999–1005.(c) El-Gazzar MG, Nafie NH, Nocentini A, et al.
Carbonic anhydrase inhibition with a series of novel benze-
nesulfonamide-triazole conjugates. J Enzyme Inhib Med
Chem 2018;33:1565–74.(d) Akocak S, Lolak N, Bua S,
Supuran CT. Discovery of novel 1,3-diaryltriazene sulfona-
mides as carbonic anhydrase I, II, VII, and IX inhibitors. J
Enzyme Inhib Med Chem 2018;33:1575–80.
€
Senturk M, et al. In vitro inhibition of a-carbonic anhydrase
isozymes by some phenolic compounds. Bioorg Med Chem
Lett 2011;21:4259–62.
20. (a) Supuran CT, Clare BW. Carbonic anhydrase inhibitors.
Part 57. Quantum chemical QSAR of a group of 1,3,4-thiadia-
zole and 1,3,4-thiadiazoline disulfonamides with carbonic
anhydrase inhibitory properties. Eur J Med Chem 1999;34:
41–50.(b) Supuran CT, Ilies MA, Scozzafava A. Carbonic anhy-
drase inhibitors. Part 29. Interaction of isozymes I, II and IV
with benzolamide-like derivatives. Eur J Med Chem 1998;33:
€
€
739–52.(c) Senturk M, Gulc¸in I, Das¸tan A, et al. Carbonic
anhydrase inhibitors. Inhibition of human erythrocyte iso-
zymes I and II with a series of antioxidant phenols. Bioorg
Med Chem 2009;17:3207–11.
19. (a) Nocentini A, Bonardi A, Gratteri P, et al. Steroids interfere
with human carbonic anhydrase activity by using alternative