Synthesis of 1-(methanesulfonyl- and aminosulfonylphenyl)acetylenes that possess a 2-(N-difluoromethyl-1,2-dihydropyridin-2-one) pharmacophore: Evaluation as dual inhibitors of cyclooxygenases and 5-lipoxygenase with anti-inflammatory activity

Article abstract of DOI:10.1016/j.bmcl.2008.12.066

A hitherto unknown class of linear acetylene regioisomers were designed such that a SO₂Me or SO₂NH₂ group was located at the ortho-, meta- or para-position of the acetylene C-1 phenyl ring, and a N-difluoromethyl-1,2-dihyd

Full text of DOI:10.1016/j.bmcl.2008.12.066

Bioorganic & Medicinal Chemistry Letters 19 (2009) 584–588
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis of 1-(methanesulfonyl- and aminosulfonylphenyl)acetylenes
that possess a 2-(N-difluoromethyl-1,2-dihydropyridin-2-one) pharmacophore:
Evaluation as dual inhibitors of cyclooxygenases and 5-lipoxygenase
with anti-inflammatory activity
Morshed Alam Chowdhury, Khaled R. A. Abdellatif, Ying Dong, Moshfiqur Rahman, Dipankar Das,
*
Mavanur R. Suresh, Edward E. Knaus
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alta., Canada T6G 2N8
a r t i c l e i n f o
a b s t r a c t
Article history:
A hitherto unknown class of linear acetylene regioisomers were designed such that a SO2Me or SO2NH2
group was located at the ortho-, meta- or para-position of the acetylene C-1 phenyl ring, and a N-difluo-
romethyl-1,2-dihydropyridin-2-one moiety was attached via its C-5 position to the C-2 position on an
acetylene template (scaffold). All three SO2Me regioisomers, and the 4-SO2NH2 analog, were potent inhib-
Received 26 November 2008
Revised 15 December 2008
Accepted 16 December 2008
Available online 24 December 2008
itors of 5-lipoxygenase (5-LOX IC50 = 3.2–3.5
lM range) relative to the reference drug caffeic acid
(IC50 = 4.0 M). The SO2Me regioisomers exhibited weak cyclooxygenease-1 (COX-1) and -2 (COX-2)
l
Keywords:
Linear acetylenes
N-Difluoromethyl-1,2-dihydropyridin-2-
ones
Cyclooxygenase-1
Cyclooxygenase-2 and 5-lipoxygenase
inhibition
Anti-inflammatory activity
inhibitory activity with a modest COX-2 selectivity index. The most potent 3-SO2Me, 4-SO2Me and 4-
SO2NH2 compounds, with respective ED50 values of 66.1, 68.5 and 86.5 mg/kg po, exhibited comparable
oral anti-inflammatory (AI) activity to that of the reference drug ibuprofen (ED50 = 67.4 mg/kg po). The
N-difluoromethyl-1,2-dihydropyridin-2-one moiety provides a novel pharmacophore for the design of
cyclic hydroxamic mimetics capable of inhibiting 5-LOX for exploitation in the development of 5-LOX
inhibitory AI drugs.
Ó 2009 Elsevier Ltd. All rights reserved.
A group of 1-(aryl)-2-(pyridyl)acetylene regioisomers (1) were
recently reported that are inhibitors of the cyclooxygenase-1
(COX-1) and/or cyclooxygenase-2 (COX-2) isozymes (see structure
in Fig. 1).1 Subsequent replacement of the pyridyl ring in the
The target 1-(2-, 3- and 4-methanesulfonylphenyl and 4-aminos-
ulfonylphenyl)-2-[5-(1-difluoromethyl-1,2-dihydropyrid-2-one)]-
acetylenes (9a–d) were prepared using the reaction sequence
illustrated in Scheme 1. 2-Iodothioanisole (3a)3 and 3-iodothioani-
sole (3b)4 were synthesized in 91% and 76% yield starting from the
respective 2-(methylthio)aniline and 3-(methylthio)aniline using
the procedure of Ullmann.5 The Sonogashira cross-coupling
reaction of 2-amino-5-ethynylpyridine (4)6 with a halothioanisole
(3a–c), or 4-bromobenzenesulfonamide (3d),7 in the presence of cu-
prous iodide (CuI), dichlorobis(triphenylphosphine)palladium(II)
acetylenes
1 by a N-hydroxy-1,2-dihydropyridin-2-one cyclic
hydroxamic acid moiety, that has the potential to chelate iron, pro-
vided a novel class of 5-lipoxygenase (5-LOX) inhibitors (2).2 It was
anticipated that elaboration of the pyridyl ring present in the
1-(aryl)-2-(pyridyl)acetylene regioisomers (1) to a N-difluoro-
methyl-1,2-dihydropyridin-2-one moiety would provide a poten-
tial 5-LOX pharmacophore. This concept is based on the premise
that the N-difluoromethyl-1,2-dihydropyridin-2-one group may
bind to, or chelate iron present in the 5-LOX enzyme. Hybrid com-
pounds of this type also containing a suitably positioned methane-
sulfonyl (MeSO2) or sulfonamide (H2NSO2) COX-2 pharmacophore
constitute a potential class of dual COX/5-LOX inhibitors. Accord-
ingly, we now describe the synthesis of a novel group of linear
acetylenes (9a–d) that possess COX-2 and 5-LOX pharmacophores,
their in vitro evaluation as 5-LOX, COX-1/COX-2 inhibitors, and
in vivo assessment as anti-inflammatory agents.
OH
3
2
2
3
R1
4
R1
4
N
Het
C
C
C
C
O
2, R1 = 2-, 3-, 4-SO2NH2
1, Het = 2-, 3-, 4-pyridyl
R1 = 2-, 3-, 4-SO2NH2
R1 = 2-, 3-, 4-SO2Me
* Corresponding author. Tel.: +1 780 492 5993; fax: +1 780 492 1217.
E-mail address: eknaus@pharmacy.ualberta.ca (E.E. Knaus).
Figure 1. Linear acetylenes that exhibit COX-1 and COX-2 (1), and 5-LOX (2),
inhibitory activities.
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2008.12.066

M. A. Chowdhury et al. / Bioorg. Med. Chem. Lett. 19 (2009) 584–588
585
3
2
3
2
R1
4
N
R1
4
N
a
R2
+ H
C
C
NH2
NHAc
NAc
C
C
NH2
3a, R1 = 2-SMe, R2 = I
3b, R1 = 3-SMe, R2 = I
3c, R1 = 4-SMe, R2 = Br
4
5a, R1 = 2-SMe (87%)
5b, R1 = 3-SMe (56%)
5c, R1 = 4-SMe (69%)
5d, R1 = 4-SO2NH2 (22%)
3d, R1 = 4-SO2NH2, R2 = Br
R1
R1
N
N
b
c
C
C
C
C
NHAc
6a, R1 = 2-SMe (66%)
6b, R1 = 3-SMe 95%)
6c, R1 = 4-SMe (87%)
6d, R1 = 4-SO2NH2 (88%)
7a, R1 = 2-SO2Me (52%)
7b, R1 = 3-SO2Me (95%)
7c, R1 = 4-SO2Me (77%)
CHF2
N
CHF2
R1
R1
N
e
d
C
C
O
C
C
9a, R1 = 2-SO2Me (66%)
9b, R1 = 3-SO2Me (81%)
9c, R1 = 4-SO2Me (100%)
9d, R1 = 4-SO2NH2 (72%)
8a, R1 = 2-SO2Me (88%)
8b, R1 = 3-SO2Me (74%)
8c, R1 = 4-SO2Me (75%)
8d, R1 = 4-SO2NH2 (46%)
Scheme 1. Reagents and conditions: (a) Et3N–THF, PPh3, Pd(PPh3)2Cl2, CuI, 75–80 °C, overnight; (b) Ac2O, 80 °C, 4 h; (c) OxoneÒ, MeOH–THF–H2O, 25 °C, 2 h, (6a–c); (d)
ClCF2COONa, MeCN, reflux, 18 h (6d, 7a–c); (e) 1% KHSO4, MeCN, reflux, 2 h.
([Pd(PPh3)2Cl2]) catalyst and triphenylphosphine (PPh3) in
Et3N–THF under an argon atmosphere6 afforded the 1-(2-, 3- or 4-
methylthiophenyl and 4-aminosulfonylphenyl)-2-(2-aminopyrid-
5-yl)acetylenes (5a–d) in 22–87% yield. Acetylation of the amino
group in 5a–d using acetic anhydride8 at 80 °C afforded the
1-(2-, 3- or 4-methylthiophenyl and 4-aminosulfonylphenyl)-2-
(2-acetamidopyrid-5-yl)acetylenes (6a–d) in 66–95% yields. Oxida-
tion of the thiomethyl substituent in 6a–c to a methylsulfonyl group
using an aqueous solution of OxoneÒ (potassium peroxymono-
sulfate)1 in MeOH–THF afforded the 1-(2-, 3- or 4-methanesulfonyl-
phenyl)-2-(2-acetamidopyrid-5-yl)acetylene regioisomers (7a–c)
in 52–95% yields. The difluoromethylation of 6d and 7a–c with
1.2 equiv of sodium chlorodifluoroacetate9 (ClCF2COONa) pro-
ceeded smoothly in refluxing acetonitrile to furnish the expected
1-(2-, 3- or 4-methanesulfonylphenyl and 4-aminosulfonylphe-
nyl)-2-[5-(1-difluoromethyl-1,2-dihydropyridin-2-acetylimino]-
acetylenes (8a–d) in 46–88% yields. Subsequent hydrolysis of
8a–d with 1% aq potassium hydrogen sulfate9 afforded the target
1-(2-, 3- and 4-methanesulfonylphenyl and 4-aminosulfonylphe-
nyl)-2-[5-(1-difluoromethyl-1,2-dihydropyrid-2-one)]acetylenes (9a–d)
in 66–100% isolated yield.
Therationalforthedesignofthe1-(2-, 3-and4-methanesulfonyl-
phenyl and 4-aminosulfonylphenyl)-2-[5-(1-difluoromethyl-1,2-
dihydropyrid-2-one)]acetylenes (9a–d) was based on the
expectation that replacement of a pyridyl ring in the 1-(aryl)-2-(pyr-
idyl)acetylene regioisomers (1), or replacement of the N-hydroxy-
pyridin-2(1H)one moiety present in the 1-(benzenesulfonamido)-2-
[5-(N-hydroxypyrid-2(1H)-one)]acetylene regioisomers (2), would
furnish a novel class of compounds with dual 5-LOX/COX-2 inhibi-
tory activities. The CONCHF2 part of the N-difluoromethyl-1,2-
dihydropyrid-2-one ring present in 9a–d can be viewed as a cyclic
hydroxamic acid mimetic. These N-difluoromethyl-1,2-dihydropy-
rid-2-ones, like acyclic hydroxamic acids, are expected to serve as
effective iron chelators to exhibit 5-LOX inhibitory activity. It has
been reported that there is a substantial build-up of negative poten-
tial around the two fluorine atoms of a CHF2 group.10 Despite this
high electron-density, an aliphatic fluorine seldom acts as a hydro-
gen-bond acceptor, presumably due to its high electronegativity
and low polarizability.11,12 Instead, it is plausible that the CHF2 group
may interact with a positively charged region on the enzyme that
may contribute to enhanced affinity and competitive reversible inhi-
bition of the COX and/or 5-LOX enzymes.13 In addition, these cyclic
N-difluoromethyl-1,2-dihydropyrid-2-ones, unlike acyclic hydroxa-
mic acids which undergo facile biotransformation to the acids, are
expected to have a greater metabolic stability with improved oral
efficacy. Although there is some distortion from planarity at the
N1-nitrogen atom of the N-difluoromethyl-1,2-dihydropyrid-2-one
ring system, the relatively flat diene portion of this quasi-planar ring
system has the potential to serve as a suitable replacement for the
pyridyl group in the 1-(aryl)-2-(pyridyl)acetylene regioisomers (1)
resulting in retention of selective COX-2 inhibitory activity.
In vitro COX-1 and COX-2 enzyme inhibition studies showed that
the N-difluoromethyl-1,2-dihydropyrid-2-ones (9a–d) were much
weaker inhibitors (COX-1 IC50 = 5.2 to >100
IC50 = 3.7–9.4 M range) than the selective COX-2 inhibitor celecoxib
(COX-1 IC50 = 7.7 M; COX-2IC50 = 0.12 M)(see datainTable 1). The
lM range; COX-2
l
l
l
MeSO2 regioisomers 9a–c are more potent inhibitors of COX-2 than
COX-1 thereby showing some COX-2 selectivity. The 4-SO2Me (9c)
and 4-SO2NH2 (9d) compounds exhibited relatively similar COX-1/
COX-2 inhibitory activity. In contrast, all N-difluoromethyl-1,2-
dihydropyrid-2-ones (9a–d) were more potent in vitro inhibitors of
the potato 5-LOX enzyme (IC50 = 3.2–3.5
lM range) than the refer-
ence drug caffeic acid (IC50 = 4.0 M). This small difference in 5-LOX
l
inhibitory potency for compounds9a–d suggests that the N-difluoro-
methyl-1,2-dihydropyrid-2-one, rather than the position (ortho, meta
or para) of the methanesulfonyl or aminosulfonyl COX-2 pharmaco-
phore, is the major determinant of 5-LOX inhibitory activity.
The oral AI activities (ED50 values) exhibited by the N-difluoro-
methyl-1,2-dihydropyrid-2-ones (9a–d) were determined using a
carrageenan-induced rat foot paw edema model (see data in Table
1). The AI structure–activity data acquired showed that the 3-
SO2Me (9b, ED50 = 66.1 mg/kg po), 4-SO2Me (9c, ED50 = 68.5 mg/

586
M. A. Chowdhury et al. / Bioorg. Med. Chem. Lett. 19 (2009) 584–588
Table 1
In vitro COX-1, COX-2, 5-LOX enzyme inhibition, and in vivo anti-inflammatory activity, data for the 1-(2-, 3- and 4-methanesulfonylphenyl and 4-aminosulfonylphenyl)-2-[5-(1-
difluoromethyl-1,2-dihydropyrid-2-one)]acetylenes (9a–d)
CHF2
2
3
R1
N
4
C
C
O
R1
COX-1 IC50
(
lM)
COX-2 IC50
(
lM)
5-LOX IC50 (lM)
AI activityc ED50 (mg/kg)
a
a
b
Compound
9a
9b
9c
9d
2-SO2Me
3-SO2Me
4-SO2Me
4-SO2NH2
>100
32.4
14.1
5.2
7.7
2.9
9.4
3.7
5.1
6.0
0.12
1.1d
2.4d
—
3.4
3.2
3.3
3.5
—
—
—
4.0
>100
66.1
68.5
86.5
10.8
67.4
128.9
—
Celecoxib
Ibuprofen
Aspirin
Caffeic acid
0.35
—
a
The in vitro test compound concentration required to produce 50% inhibition of ovine COX-1 or human recombinant COX-2. The result (IC50, lM) is the mean of two
determinations acquired using the enzyme immuno assay kit (Catalog No. 560131, Cayman Chemicals, Inc., Ann Arbor, MI, USA) and the deviation from the mean is <10% of
the mean value.
b
The in vitro test compound concentration required to produce 50% inhibition of potato 5-LOX (Cayman Chemicals, Inc., Catalog No. 60401). The result (IC50, lM) is the
mean of two determinations acquired using a LOX assay kit (Catalog No. 760700, Cayman Chemicals, Inc., Ann Arbor, MI, USA) and the deviation from the mean is <10% of the
mean value.
c
Inhibitory activity in a carrageenan-induced rat paw edema assay. The results are expressed as the ED50 value (mg/kg) at 3 h after oral administration of the test
compound.
d
Data acquired using ovine COX-2 (Catalog No. 560101, Cayman Chemicals, Inc.).
kg po) and 4-SO2NH2 (9d, ED50 = 86.5 mg/kg po), compounds
exhibited AI activities that were more similar to that of the refer-
ence drug ibuprofen (ED50 = 67.4 mg/kg po) than the selective
COX-2 inhibitor celecoxib (ED50 = 10.8 mg/kg po) or the non-selec-
tive COX inhibitor aspirin (ED50 = 128.9 mg/kg po). The in vitro and
in vivo structure–activity data acquired suggest that the N-difluo-
romethyl-1,2-dihydropyrid-2-ones (9b–d), that are weak inhibi-
tors of the COX-1 and COX-2 isozymes, exhibit their AI effect to a
significant degree by preventing the biosynthesis of proinflamma-
tory leukotrienes (LTs) produced via the LOX pathway.
anti-inflammatory activity17 that is dependent upon inhibition of
proinflammatory leukotriene biosynthesis in the lipoxygenase
pathway.
Acknowledgment
We are grateful to the Canadian Institutes of Health Research
(CIHR) (MOP-14712) for financial support of this research.
References and notes
The N-hydroxypyrid-2(1H)-one regioisomers (2, R1 = 2-, 3- and
4-SO2NH2) reported previously exhibited excellent 5-LOX inhibi-
1. Chowdhury, M. A.; Dong, Y.; Chen, Q.-H.; Abdellatif, K. R. A.; Knaus, E. E. Bioorg.
Med. Chem. 2008, 16, 1948.
2. Chowdhury, M. A.; Chen, H.; Abdellatif, K. R. A.; Dong, Y.; Petruk, K. C.; Knaus, E.
E. Bioorg. Med. Chem. Lett. 2008, 18, 4195.
3. Larock, R. C.; Harrison, W. J. Am. Chem. Soc 1984, 106, 4218.
4. Mongin, O.; Papamicaël, C.; Hoyler, N.; Gossauer, A. J. Org. Chem. 1998, 63, 5568.
5. Ullmann, F. Justus Liebigs Ann. Chem. 1904, 332, 69.
6. Aakeröy, C. B.; Schultheiss, N.; Desper, J. Dalton Trans. 2006, 1627.
7. Anana, R.; Rao, P. N. P.; Chen, Q.-H.; Knaus, E. E. Bioorg. Med. Chem. 2006, 14, 5259.
8. Sollogoub, M.; Fox, K. R.; Powers, V. E. C.; Brown, T. Tetrahedron Lett. 2002, 43, 3121.
9. Ando, M.; Wada, T.; Sato, N. Org. Lett. 2006, 8, 3805.
tory activities (IC50 = 10–68
lM range) relative to the reference
drug nordihydroguaiaretic acid (NDGA, IC50 = 35
lM) determined
using a cell-based enzyme immuno assay. In spite of this high
in vitro 5-LOX inhibitory activity, only the 2-SO2NH2 regioisomer
(2) exhibited in vivo AI activity (ED50 = 86 mg/kg po).2 In compar-
ison, the N-difluoromethyl-1,2-dihydropyrid-2-ones 9a–d, as indi-
cated above, were potent in vitro inhibitors of the isolated potato
10. Narjes, F.; Koehler, K. F.; Koch, U.; Gerlach, B.; Colarusso, S.; Steinkühler, C.;
Brunetti, M.; Altamura, S.; De Francesco, R.; Matassa, V. G. Bioorg. Med. Chem.
Lett. 2002, 12, 701. and references cited therein.
5-LOX enzyme (IC50 = 3.2–3.5
lM range) similar to the reference
drug caffeic acid (IC50 = 4.0 M). In contrast, all of the N-difluoro-
l
methyl-1,2-dihydropyrid-2-ones 9, with the exception of the
2-SO2Me regioisomer 9a, exhibited good AI activity. These latter
differences in AI structure–activity relationships suggests the N-
difluoromethyl-1,2-dihydropyrid-2-one moiety may have more
favorable bioavailability, biodistribution and/or metabolic proper-
ties making it more suitable than the N-hydroxypyrid-2(1H)-one
moiety as a 5-LOX pharmacophore.
In conclusion, a hitherto unknown class of 1-(2-, 3- and 4-meth-
anesulfonylphenyl and 4-aminosulfonylphenyl)-2-[5-(1-difluoro-
methyl-1,2-dihydropyrid-2-one)]acetylenes (9a–d)14 was designed
for evaluation as dual 5-LOX15 and COX-1/COX-2 isozyme16 inhib-
itors of inflammation. The structure–activity data acquired indicate
that (i) the relative AI potency order with respect to the aryl sub-
stituent is 3-SO2Me (9b) ꢀ 4-SO2Me (9c) > 4-SO2NH2 ꢁ 2-SO2Me
(9a), (ii) the N-difluoromethyl-1,2-dihydropyrid-2-one moiety pro-
vides a novel 5-LOX pharmacophore for the design of cyclic
hydroxamic mimetics and (iii) the title compounds 9b–d, that
are very weak inhibitors of the COX-1/COX-2 isozymes, exhibit
11. Dunitz, J. D.; Taylor, R. Chem. Eur. J. 1997, 3, 89.
12. Howard, J. A. K.; Hoy, V. J.; O’Hagan, D.; Smith, G. T. Tetrahedron 1996, 52, 12613.
13. Chavatte, P.; Yous, S.; Marot, C.; Baurin, N.; Lesieur, D. J. Med. Chem. 2001, 44, 3223.
14. Experimental procedures and spectral data for compounds 5a–d, 6a–d, 7a–c,
8a–d and 9a–d. General procedure for the synthesis of 1-(2-, 3- or 4-
methylthiophenyl and 4-aminosulfonylphenyl)-2-(2-aminopyrid-5-yl)acetylenes
(5a–d). Bis(triphenylphosphine)palladium(II) dichloride (0.22 g, 0.32 mmol),
copper(I) iodide (0.05 g, 0.26 mmol) and triphenylphosphine (0.22 g,
0.84 mmol) were added to a stirred solution of 2-amino-5-ethynylpyridine (4,
1.03 g, 8.70 mmol) and a bromo- or iodothioanisole (3a, 3b or 3c), or 4-
bromobenzenesulfonamide (3d), (10.12 mmol) in Et3N–THF (1:1 v/v, 60 mL) at
25 °C. Dry argon was bubbled through the resultant mixture for 10 min. The
reaction was allowed to proceed at 80 °C overnight under an argon atmosphere,
the mixture was cooled to 25 °C, and filtered to remove the inorganic salts. The
solvent from the filtrate was removed in vacuo, and the residue obtained was
purified by silica gel column chromatography using hexanes/EtOAc (1:3, v/v) as
eluent to furnish the respective product 5a–d. Some physical and spectroscopic
data for 5a–d are listed below.
1-(2-Methylthiophenyl)-2-(2-aminopyrid-5-yl)acetylene (5a). The product was
obtained as a pale yellow solid using the Sonogashira cross-coupling reaction of
2-iodothioanisole (3a) with 4 in 87% yield; mp 103–105 °C; IR (film): 3370, 3300
(NH2), 2200 (C„C) cmÀ1 1H NMR (CDCl3) d 2.51 (s, 3H, SMe), 4.62 (br s, 2H, NH2
;
that exchanges with D2O), 6.48 (d, J = 8.5 Hz, 1H, pyridyl H-3), 7.11 (ddd, J = 7.3,

M. A. Chowdhury et al. / Bioorg. Med. Chem. Lett. 19 (2009) 584–588
587
7.3, 1.2 Hz, 1H, phenyl H-5), 7.18 (dd, J = 7.3, 1.2 Hz, 1H, phenyl H-3), 7.30 (ddd,
J = 7.3, 7.3, 1.2 Hz, 1H, phenyl H-4), 7.46 (dd, J = 7.3, 1.2 Hz, 1H, phenyl H-6), 7.61
(dd, J = 8.5, 1.8 Hz, 1H, pyridyl H-4), 8.32 (d, J = 1.8 Hz, 1H, pyridyl H-6); 13CNMR
(CDCl3) d 15.1, 87.3, 93.5, 107.9, 109.8, 121.4, 124.0, 124.2, 128.5, 131.9, 140.3,
141.2, 151.4, 157.5.
1-(2-Methanesulfonylphenyl)-2-(2-acetamidopyrid-5-yl)acetylene (7a). The
product was obtained as a white solid in 52% yield; mp 180–182 °C; IR (film):
3330 (NH), 2200 (C„C), 1700 (CO), 1300, 1150 (SO2) cmÀ1 1H NMR (CDCl3) d
;
2.25 (s, 3H, COMe), 3.31 (s, 3H, SO2Me), 7.55 (ddd, J = 7.3, 7.3, 1.2 Hz, 1H, phenyl
H-5), 7.65 (ddd, J = 7.3, 7.3, 1.2 Hz, 1H, phenyl H-4), 7.74 (dd, J = 7.3, 1.2 Hz, 1H,
phenyl H-6), 7.90 (dd, J = 9.2, 1.8 Hz, 1H, pyridyl H-4), 8.15 (dd, J = 7.3, 1.2 Hz,
1H, phenyl H-3), 8.27 (d, J = 9.2 Hz, 1H, pyridyl H-3), 8.31 (br s, 1H, NH that
exchanges with D2O), 8.50 (d, J = 1.8 Hz, 1H, pyridyl H-6); 13C NMR (CDCl3) d
24.8, 42.5, 87.7, 94.8, 113.3, 114.9, 121.6, 128.8, 128.9, 133.2, 134.2, 141.0,
141.1, 150.6, 151.1, 168.7.
1-(3-Methylthiophenyl)-2-(2-aminopyrid-5-yl)acetylene (5b). The product was
obtained as a pale yellow solid using the Sonogashira cross-coupling reaction of
3-iodothioanisole (3b) with 4 in56% yield; mp 115–117 °C;IR (film): 3300, 3250
(NH2), 2200 (C„C) cmÀ1 1H NMR (CDCl3) d 2.50 (s, 3H, SMe), 4.68 (br s, 2H, NH2
;
that exchanges with D2O), 6.48 (d, J = 8.5 Hz, 1H, pyridyl H-3), 7.15–7.30 (m, 3H,
phenyl H-4, H-5, H-6), 7.37 (s, 1H, phenyl H-2), 7.57 (dd, J = 8.5, 1.8 Hz, 1H,
pyridyl H-4), 8.28 (d, J = 1.8 Hz, 1H, pyridyl H-6); 13C NMR (CDCl3) d 15.7, 87.4,
89.4, 107.9, 109.6, 124.0, 126.2, 127.9, 128.6, 128.7, 138.8, 140.3, 151.4, 157.5.
1-(4-Methylthiophenyl)-2-(2-aminopyrid-5-yl)acetylene (5c). The product was
obtained as a pale yellow solid using the Sonogashira cross-coupling reaction of
4-bromothioanisole (3c) with 4 in 69% yield; mp 155–157 °C; IR (film): 3435,
1-(3-Methanesulfonylphenyl)-2-(2-acetamidopyrid-5-yl)acetylene (7b). The
product was obtained as a yellow solid in 95% yield; mp 170–172 °C; IR
(film): 3325 (NH), 2200 (C„C), 1700 (CO), 1300, 1150 (SO2) cmÀ1 1H NMR
;
(CDCl3) d 2.24 (s, 3H, COMe), 3.09 (s, 3H, SO2Me), 7.59 (dd, J = 7.9, 7.9 Hz, 1H,
phenyl H-5), 7.79 (ddd, J = 7.9, 1.2, 1.2 Hz, 1H, phenyl H-6), 7.85 (dd, J = 8.5,
1.8 Hz, 1H, pyridyl H-4), 7.92 (dd, J = 7.9, 1.2 Hz, 1H, phenyl H-4), 8.12 (dd,
J = 1.2, 1.2 Hz, 1H, phenyl H-2), 8.15 (br s, 1H, NH that exchanges with D2O), 8.26
(d, J = 8.5 Hz, 1H, pyridyl H-3), 8.45 (d, J = 1.8 Hz, 1H, pyridyl H-6); 13C NMR
(CDCl3) d 24.8, 44.4, 88.3, 89.4, 113.3, 115.1, 124.5, 126.9, 129.5, 130.4, 136.2,
141.0, 141.1, 150.5, 150.8, 168.7.
3305 (NH2), 2200 (C„C) cmÀ1 1H NMR (CDCl3) d 2.50 (s, 3H, SMe), 4.59 (br s, 2H,
;
NH2 that exchanges with D2O), 6.48 (d, J = 8.5 Hz, 1H, pyridyl H-3), 7.20 (dd,
J = 8.5, 1.8 Hz, 2H, phenyl H-3, H-5), 7.41 (dd, J = 8.5, 1.8 Hz, 2H, phenyl H-2, H-
6), 7.55 (dd, J = 8.5, 1.8 Hz, 1H, pyridyl H-4), 8.27 (d, J = 1.8 Hz, 1H, pyridyl H-6);
13CNMR (CDCl3) d15.4, 87.0, 89.6, 107.9, 110.0, 119.6, 125.9, 131.6, 139.0, 140.3,
151.3, 157.3.
1-(4-Methanesulfonylphenyl)-2-(2-acetamidopyrid-5-yl)acetylene (7c). The
product was obtained as a pale yellow solid in 77% yield; mp 205–207 °C; IR
1-(4-Aminosulfonylphenyl)-2-(2-aminopyrid-5-yl)acetylene (5d). The product
was obtained as a pale yellow solid using the Sonogashira cross-coupling
reaction of 3d with 4 in 22% yield; mp 248–250 °C; IR (film): 3480, 3367, 3323
(film): 3360 (NH), 2200 (C„C), 1700 (CO), 1300, 1150 (SO2) cmÀ1 1H NMR
;
(CDCl3) d 2.24 (s, 3H, COMe), 3.09 (s, 3H, SO2Me), 7.71 (dd, J = 8.5, 1.8 Hz, 2H,
phenyl H-2, H-6), 7.85 (dd, J = 8.5, 1.8 Hz, 1H, pyridyl H-4), 7.95 (dd, J = 8.5,
1.8 Hz, 2H, phenyl H-3, H-5), 8.10 (br s, 1H, NH that exchanges with D2O), 8.25
(d, J = 8.5 Hz, 1H, pyridyl H-3), 8.46 (d, J = 1.8 Hz, 1H, pyridyl H-6); 13C NMR
(CDCl3) d 24.8, 44.5, 89.9, 113.2, 115.0, 127.5, 128.6, 132.2, 139.8, 141.1, 150.7,
150.9, 168.6.
General procedure for the synthesis of 1-(2-, 3- or 4-methanesulfonylphenyl and 4-
aminosulfonylphenyl)-2-[5-(1-difluoromethyl-1,2-dihydropyrid-2-acetylimino)]
acetylenes (8a–d). Sodium chlorodifluoroacetate (0.68 g, 4.46 mmol) was added
(NH2), 2217 (C„C), 1311, 1167 (SO2) cmÀ1 1H NMR (DMSO-d6) d 6.46 (d,
;
J = 8.5 Hz, 1H, pyridyl H-3), 6.51(br s, 2H, NH2 that exchanges with D2O), 7.43 (br
s, 2H, SO2NH2 that exchanges with D2O), 7.53 (dd, J = 8.5, 2.4 Hz, 1H, pyridyl H-
4), 7.65 (d, J = 8.5 Hz, 2H, phenyl H-2, H-6), 7.81 (d, J = 8.5 Hz, 2H, phenyl H-3, H-
5), 8.15 (d, J = 2.4 Hz, 1H, pyridyl H-6); 13C NMR (CDCl3) d 88.3, 89.7, 106.9,
108.6, 125.8, 126.6, 130.9, 140.2, 142.6, 149.4, 157.9.
General procedure for the synthesis of 1-(2-, 3- or 4-methylthiophenyl and 4-
aminosulfonylphenyl)-2-(2-acetamidopyrid-5-yl)acetylenes (6a–d). A solution of
to
a stirred solution of a 1-(2-, 3- or 4-methanesulfonylphenyl or
a
1-(2-, 3- or 4-methylthiophenyl or 4-aminosulfonylphenyl)-2-(2-
aminosulfonylphenyl)-2-(2-acetamidopyrid-5-yl)acetylene (6d, 7a–c, 3.66
mmol) in dry acetonitrile (75 mL), and the mixture was heated at reflux for
18 h under an argon atmosphere. At this time, the mixture was concentrated
and saturated aqueous NaHCO3 (25 mL) was added and this mixture was
extracted with EtOAc (3 Â 30 mL). The combined organic phases were washed
with brine, and dried (MgSO4). After filtration, the solvent from the organic
fraction was removed in vacuo to give a crude product which was purified by
silica gel column chromatography using hexanes/EtOAc (1:3, v/v) as eluent to
afford the respective product 8a–d. The spectral data for compounds 8a–d are
listed below.
aminopyrid-5-yl)acetylene (5a–d) (5 mmol) in acetic anhydride (50 mL) was
heated at 80 °C for 2 h. The reaction was cooled to 25 °C, the solvent was
removed in vacuo, and the crude product was purified by silica gel column
chromatography using hexanes/EtOAc (2:1, v/v) as eluent to furnish the
respective product 6a–d. Some physical and spectroscopic data for 6a–d are
listed below.
1-(2-Methylthiophenyl)-2-(2-acetamidopyrid-5-yl)acetylene (6a). The product
was obtained as a white solid in 66% yield; mp 138–140 °C; IR (film): 3250 (NH),
2200 (C„C), 1700 (CO) cmÀ1 1H NMR (CDCl3) d 2.23 (s, 3H, COMe), 2.53 (s, 3H,
;
SMe), 7.14 (ddd, J = 7.3, 7.3, 1.2 Hz, 1H, phenyl H-5), 7.20 (dd, J = 7.3, 1.2 Hz, 1H,
phenyl H-3), 7.34 (ddd, J = 7.3, 7.3, 1.2 Hz, 1H, phenyl H-4), 7.49 (dd, J = 7.3,
1.2 Hz, 1H, phenyl H-6), 7.88 (dd, J = 8.5, 1.8 Hz, 1H, pyridyl H-4), 8.15 (br s, 1H,
NH that exchanges with D2O), 8.23 (d, J = 8.5 Hz, 1H, pyridyl H-3), 8.48 (d,
J = 1.8 Hz, 1H, pyridyl H-6); 13C NMR (CDCl3) d 15.0, 24.8, 89.2, 92.2, 113.1,
116.0, 120.7, 124.0, 124.3, 129.1, 132.2, 140.9, 141.7, 150.4, 168.5.
1-(2-Methanesulfonylphenyl)-2-[5-(1-difluoromethyl-1,2-dihydropyrid-2-acetyl-
imino)]acetylene (8a). The product was obtained as a brown solid in 88% yield;
mp 95–97 °C; IR (film): 2200 (C„C), 1670 (CO), 1300, 1150 (SO2) cmÀ1 1H NMR
;
(CDCl3) d 2.23 (s, 3H, COMe), 3.24 (s, 3H, SO2Me), 7.45 (dd, J = 9.8, 1.8 Hz, 1H,
pyridyl H-4), 7.56 (ddd, J = 7.9, 7.9, 1.2 Hz, 1H, phenyl H-5), 7.64 (ddd, J = 7.9, 7.9,
1.2 Hz, 1H, phenyl H-4), 7.70 (dd, J = 7.9, 1.2 Hz, 1H, phenyl H-6), 7.75 (d,
J = 9.8 Hz, 1H, pyridyl H-3), 7.87 (d, J = 1.8 Hz, 1H, pyridyl H-6), 8.01 (t,
J = 60.5 Hz, 1H, CHF2), 8.14 (dd, J = 7.9, 1.2 Hz, 1H, phenyl H-3); 13C NMR
(CDCl3) d 28.0, 42.6, 87.4, 92.2, 105.0, 119.8, 121.0, 129.1, 129.1, 133.1, 133.3,
134.1, 140.7, 141.0, 153.7, 182.3.
1-(3-Methylthiophenyl)-2-(2-acetamidopyrid-5-yl)acetylene (6b). The product
was obtained as a yellow solid in 95% yield; mp 125–127 °C; IR (film): 3250
(NH), 2200 (C„C), 1700 (CO) cmÀ1 1H NMR (CDCl3) d 2.23 (s, 3H, COMe), 2.51 (s,
;
3H, SMe), 7.20–7.35 (m, 3H, phenyl H-4, H-5, H-6), 7.40 (s, 1H, phenyl H-2), 7.83
(dd, J = 8.5, 1.8 Hz, 1H, pyridyl H-4), 8.23 (d, J = 8.5 Hz, 1H, pyridyl H-3), 8.26 (br
s, 1H, NH that exchanges with D2O), 8.42 (d, J = 1.8 Hz, 1H, pyridyl H-6); 13CNMR
(CDCl3) d 15.6, 24.7, 85.9, 91.4, 113.6, 115.9, 123.2, 126.7, 128.0, 128.6, 128.8,
139.0, 141.3, 149.7, 150.5, 168.8.
1-(3-Methanesulfonylphenyl)-2-[5-(1-difluoromethyl-1,2-dihydropyrid-2-acetyl-
imino)]acetylene (8b). The product was obtained as a yellow solid in 74% yield;
mp 132–134 °C; IR (film): 2200 (C„C), 1670 (CO), 1300, 1150 (SO2) cmÀ1 1H
;
NMR (CDCl3) d 2.23 (s, 3H, COMe), 3.09 (s, 3H, SO2Me), 7.40 (dd, J = 9.8, 2.5 Hz,
1H, pyridyl H-4), 7.59 (dd, J = 7.9, 7.9 Hz, 1H, phenyl H-5), 7.75 (ddd, J = 7.9, 1.8,
1.8 Hz, 1H, phenyl H-6), 7.78 (d, J = 9.8 Hz, 1H, pyridyl H-3), 7.83 (d, J = 2.5 Hz,
1H, pyridyl H-6), 7.93 (ddd, J = 7.9, 1.8, 1.8 Hz, 1H, phenyl H-4), 8.02 (t,
J = 60.5 Hz, 1H, CHF2), 8.08 (dd, J = 1.8, 1.8 Hz, 1H, phenyl H-2); 13C NMR (CDCl3)
d 27.9, 44.3, 85.7, 89.2, 105.4, 119.8, 123.8, 127.2, 129.6, 130.3, 133.0, 136.1,
141.0, 141.1, 153.5, 181.9.
1-(4-Methylthiophenyl)-2-(2-acetamidopyrid-5-yl)acetylene (6c). The product
was obtained as a pale yellow solid in 87% yield; mp 200–202 °C; IR (film):
3250 (NH), 2200 (C„C), 1700 (CO) cmÀ1 1H NMR (CDCl3) d 2.23 (s, 3H, COMe),
;
2.51 (s, 3H, SMe), 7.22 (dd, J = 8.5, 1.8 Hz, 2H, phenyl H-3, H-5), 7.44 (dd, J = 8.5,
1.8 Hz, 2H, phenyl H-2, H-6), 7.82 (dd, J = 8.5, 1.8 Hz, 1H, pyridyl H-4), 8.05 (br s,
1H, NH that exchanges with D2O), 8.21 (d, J = 8.5 Hz, 1H, pyridyl H-3), 8.42 (d,
J = 1.8 Hz, 1H, pyridyl H-6); 13C NMR (CDCl3) d 15.3, 24.8, 85.9, 91.6, 113.1,
116.2, 118.9, 125.8, 131.8, 139.8, 140.8, 150.1, 150.3, 168.5.
1-(4-Methanesulfonylphenyl)-2-[5-(1-difluoromethyl-1,2-dihydropyrid-2-acetyl-
imino)]acetylene (8c). The product was obtained as a pale yellow solid in 75%
1-(4-Aminosulfonylphenyl)-2-(2-acetamidopyrid-5-yl)acetylene
product was obtained as a pale yellow solid in 88% yield; mp 225–227 °C; IR
(film): 3321 (NH), 2217 (C„C), 1700 (CO), 1334, 1150 (SO2) cmÀ1 1H NMR
(6d).
The
yield; mp 160–162 °C; IR (film): 2200 (C„C), 1670 (CO), 1300, 1150 (SO2) cmÀ1
;
1H NMR (CDCl3) d 2.24 (s, 3H, COMe), 3.09 (s, 3H, SO2Me), 7.41 (dd, J = 9.8, 1.8 Hz,
1H, pyridyl H-4), 7.68 (dd, J = 8.5, 1.8 Hz, 2H, phenyl H-2, H-6), 7.78 (d, J = 9.8 Hz,
1H, pyridyl H-3), 7.85 (d, J = 1.8 Hz, 1H, pyridyl H-6), 7.95 (dd, J = 8.5, 1.8 Hz, 2H,
phenyl H-3, H-5), 8.03 (t, J = 60.5 Hz, 1H, CHF2); 13C NMR (CDCl3) d 28.0, 44.4,
87.4, 89.5, 105.0, 119.8, 127.5, 127.9, 132.2, 133.1, 140.2, 140.9, 153.7, 182.3.
1-(4-Aminosulfonylphenyl)-2-[5-(1-difluoromethyl-1,2-dihydropyrid-2-acetylimino)]
acetylene (8d). The product was obtained as a pale yellow solid in 46% yield; mp
208–210 °C; IR (film): 3300 (broad NH2), 2219 (C„C), 1700 (CO), 1294, 1163
;
(CDCl3 + DMSO-d6) d 2.10 (s, 3H, COMe), 7.21 (br s, 2H, SO2NH2 that exchanges
with D2O), 7.56 (d, J = 8.5 Hz, 2H, phenyl H-2, H-6), 7.75 (dd, J = 8.5, 2.4 Hz, 1H,
pyridyl H-4), 7.82 (d, J = 8.5 Hz, 2H, phenyl H-3, H-5), 8.13 (d, J = 8.5 Hz, 1H,
pyridyl H-3), 8.39 (d, J = 2.4 Hz, 1H, pyridyl H-6), 10.48 (br s, 1H, NH that
exchanges with D2O); 13C NMR (CDCl3) d 22.9, 88.5, 89.3, 125.5, 125.6, 127.5,
131.1, 138.4, 140.1, 143.2, 151.4, 169.1.
General procedure for the synthesis of 1-(2-, 3- or 4-methylsulfonylphenyl)-2-(2-
(SO2) cmÀ1 1H NMR (DMSO-d6) d 2.11 (s, 3H, COMe), 7.47 (br s, 2H, SO2NH2 that
;
acetamidopyrid-5-yl)acetylenes (7a–c). An aqueous solution of OxoneÒ (6.14 g,
exchanges with D2O), 7.59 (d, J = 9.8 Hz, 1H, pyridyl H-3), 7.67 (dd, J = 9.8,
1.8 Hz, 1H, pyridyl H-4), 7.73 (d, J = 8.5 Hz, 2H, phenyl H-2, H-6), 7.86 (d,
J = 8.5 Hz, 2H, phenyl H-3, H-5), 8.10 (t, J = 60.5 Hz, 1H, CHF2), 8.42 (d, J = 1.8 Hz,
1H, pyridyl H-6); 13C NMR (CDCl3 + DMSO-d6) d 27.3, 85.8, 89.6, 102.5, 119.1,
124.9, 125.7, 131.1, 133.3, 141.3, 143.7, 152.5, 180.1.
General procedure for the synthesis of 1-(2-, 3- or 4-methanesulfonylphenyl and
4-aminosulfonylphenyl)-2-[5-(1-difluoromethyl-1,2-dihydropyrid-2-one)]acetylenes
(9a–d). A solution of 1% aq KHSO4 (45 mL) was added to a stirred solution of a
1-difluoromethyl-1,2-dihydropyrid-2-acetylimino compound (8a–d, 3.10
mmol) in acetonitrile (45 mL), and the mixture was heated at reflux for 3 h.
At this time, the mixture was concentrated in vacuo, 0.5 N HCl (25 mL) was
10 mmol, 18 mL) was added to
a stirred solution of a 1-(2-, 3- or 4-
methylthiophenyl)-2-(2-acetamidopyrid-5-yl)acetylene (6a–c) (2 mmol) in
methanol (30 mL) and THF (30 mL), and the reaction was allowed to proceed
with stirring at 25 °C for 3 h. The reaction mixture was diluted with water
(200 mL), extracted with EtOAc (3 Â 75 mL), the organic phase was washed
successively with water and brine, and dried (MgSO4). After filtration, the
solvent from the organic fraction was removed in vacuo to give a crude product
which was purified by silica gel column chromatography using hexanes/EtOAc
(1:3, v/v) as eluent to furnish the respective title compound 7a–c. Some physical
and spectroscopic data for 7a–c are listed below.

588
M. A. Chowdhury et al. / Bioorg. Med. Chem. Lett. 19 (2009) 584–588
added, and the mixture was extracted with EtOAc (3 Â 30 mL). The combined
13C NMR (CDCl3) d 44.4, 87.5, 88.9, 103.2, 107.1, 121.8, 127.5, 128.0, 132.1, 133.4,
140.0, 142.7, 159.4. Anal. Calcd for C15H11F2NO3S: C, 55.72; H, 3.43; N, 4.33. Found:
C, 55.67; H, 3.59; N, 4.27.
organic extracts were washed successively with saturated aqueous NaHCO3
and brine, and dried (MgSO4). After filtration, the solvent from the organic
fraction was removed in vacuo to give a crude product which was purified by
silica gel column chromatography using hexanes/EtOAc (1:2, v/v) as eluent to
afford the respective product 9a–d. The spectral and microanalytical data for
compounds 9a–d are listed below.
1-(4-Aminosulfonylphenyl)-2-[5-(1-difluoromethylpyrid-2-one)]acetylene
The product was obtained as white solid in 72% yield; mp 190–
192 °C; IR (film): 3315 (broad NH2), 2225 (C„C), 1675 (CO), 1352, 1165
(SO2) cmÀ1 1H NMR (CDCl3) d 6.54 (d, J = 9.8 Hz, 1H, pyridone H-3), 7.33
(9d).
a
;
1-(2-Methylsulfonylphenyl)-2-[5-(1-difluoromethylpyrid-2-one)]acetylene (9a). The
productwasobtainedasayellowsolidin66%yield;mp155–157 °C;IR(film):2200
(br s, 2H, SO2NH2 that exchanges with D2O), 7.56 (dd, J = 9.8, 1.8 Hz, 1H,
pyridone H-4), 7.60 (d, J = 8.5 Hz, 2H, phenyl H-2, H-6), 7.76 (t,
J = 60.5 Hz, 1H, CHF2), 7.83 (d, J = 8.5 Hz, 2H, phenyl H-3, H-5), 8.00 (d,
(C„C), 1700 (CO), 1300, 1150 (SO2) cmÀ1 1H NMR (CDCl3) d 3.25 (s, 3H, SO2Me),
;
6.61 (d, J = 9.8 Hz, 1H, pyridone H-3), 7.55 (dd, J = 9.8, 1.8 Hz, 1H, pyridone H-4),
7.59 (ddd, J = 7.9, 7.9, 1.2 Hz, 1H, phenyl H-5), 7.65–7.75 (m, 2H, phenyl H-4, H-6),
7.68(t, J = 60.5 Hz, 1H, CHF2), 7.80(d, J = 1.8 Hz, 1H, pyridoneH-6), 8.15(dd, J = 7.9,
1.2 Hz, 1H, phenyl H-3); 13C NMR (CDCl3) d 42.6, 86.9, 92.4, 103.2, 107.1, 121.1,
121.9, 129.0, 133.2, 133.3, 134.0, 140.9, 142.6, 159.4. Anal. Calcd for C15H11F2NO3S:
C, 55.72; H, 3.43; N, 4.33. Found: C, 55.78; H, 3.66; N, 4.32.
J = 1.8 Hz, 1H, pyridone H-6); 13C NMR (CDCl3 + DMSO-d6)
d 85.9, 88.8,
102.8, 106.9, 121.1, 125.2, 125.7, 131.1, 132.8, 142.5, 143.3, 158.7. Anal.
Calcd for C14H10F2N2O3Sꢂ1/4H2O: C, 51.14; H, 3.22; N, 8.52. Found: C,
51.05; H, 3.46; N, 8.32.
15. 5-Lipoxygenase inhibition assay: The ability of the test compounds listed in
Table 1 to inhibit potato 5-LOX (Catalog No. 60401, Cayman Chemical, Ann
1-(3-Methylsulfonylphenyl)-2-[5-(1-difluoromethylpyrid-2-one)]acetylene (9b). The
productwasobtainedasayellowsolidin81%yield;mp158–160 °C;IR(film):2200
Arbor, MI, USA) (IC50 values, lM) were determined using an enzyme immuno
assay (EIA) kit (Catalog No. 760700, Cayman Chemical, Ann Arbor, MI, USA)
according to our previously reported method. Chowdhury, M. A.; Abdellatif, K.
R. A.; Dong, Y.; Das, D.; Suresh, M. R.; Knaus, E. E. Bioorg. Med. Chem. Lett. 2008,
18, 6138.
(C„C), 1700 (CO), 1300, 1150 (SO2) cmÀ1 1H NMR (CDCl3) d 3.08 (s, 3H, SO2Me),
;
6.59 (d, J = 9.8 Hz, 1H, pyridone H-3), 7.46 (dd, J = 9.8, 2.5 Hz, 1H, pyridone H-4),
7.58 (dd, J = 7.9, 7.9 Hz, 1H, phenyl H-5), 7.67 (t, J = 60.5 Hz, 1H, CHF2), 7.74 (ddd,
J = 7.9, 1.8, 1.8 Hz, 1H, phenylH-6), 7.75(d, J = 2.5 Hz, 1H, pyridoneH-6), 7.92 (ddd,
J = 7.9, 1.8, 1.8 Hz, 1H, phenyl H-4), 8.07 (dd, J = 1.8, 1.8 Hz, 1H, phenyl H-2); 13C
NMR(CDCl3)d44.4,86.1,88.6,103.3,107.2,121.9,124.1,127.1,129.6,130.3,133.3,
136.1, 141.1, 142.8, 159.5. Anal. Calcd for C15H11F2NO3S: C, 55.72; H, 3.43; N, 4.33.
Found: C, 55.85; H, 3.58; N, 4.26.
16. Cyclooxygenase inhibition assays. The ability of the test compounds listed in
Table 1 to inhibit ovine COX-1 and human recombinant COX-2 (IC50 value, lM)
were determined using an enzyme immuno assay (EIA) kit (Catalog No.
560131, Cayman Chemical, Ann Arbor, MI, USA) according to our previously
reported method. Rao, P. N. P.; Amini, M.; Li, H.; Habeeb, A.; Knaus, E. E. J. Med.
Chem. 2003, 46, 4872.
1-(4-Methylsulfonylphenyl)-2-[5-(1-difluoromethylpyrid-2-one)]acetylene (9c). The
product was obtained as a white solid in 100% yield; mp 159–161 °C; IR (film):
17. In vivo anti-inflammatory assay. The test compounds 9a–d and the
reference drugs celecoxib, ibuprofen and aspirin were evaluated using
the in vivo carrageenan-induced rat foot paw edema model reported
previously. Winter, C. A.; Risley, E. A.; Nuss, G. W. Proc. Soc. Exp. Biol.
Med. 1962, 111, 544.
2200 (C„C), 1700 (CO), 1300, 1150 (SO2) cmÀ1 1H NMR (CDCl3) d 3.08 (s, 3H,
;
SO2Me), 6.60 (d, J = 9.8 Hz, 1H, pyridone H-3), 7.47 (dd, J = 9.8, 1.8 Hz, 1H, pyridone
H-4), 7.67 (dd, J = 8.5, 1.8 Hz, 2H, phenyl H-2, H-6), 7.68 (t, J = 60.5 Hz, 1H, CHF2),
7.77 (d, J = 1.8 Hz, 1H, pyridoneH-6), 7.94(dd, J = 8.5, 1.8 Hz, 2H, phenylH-3, H-5);