Synthesis and biological activity of new anti-inflammatory compounds containing the 1,4-benzodioxine and/or pyrrole system

Article abstract of DOI:10.1016/j.bmc.2007.04.050

A series of substituted derivatives containing the 1,4-benzodioxine or pyrrole nucleus are described. All the newly synthesized compounds were examined for their in vitro and in vivo anti-inflammatory activity. Several derivatives, including (S)-2, 14 and 17, showed more anti-inflammatory activity in vivo in these assays (rat paw oedema induced by carrageenan) than the known classical anti-inflammatory agent ibuprofen, whereas other compounds like 1 were equipotent to ibuprofen. Compound 17 was the most outstanding derivative because of its remarkable in vivo anti-inflammatory activity. In this paper, we examine and discuss the structure-activity relationships and anti-inflammatory activities of these compounds.

Full text of DOI:10.1016/j.bmc.2007.04.050

Bioorganic & Medicinal Chemistry 15 (2007) 4876–4890
Synthesis and biological activity of new anti-inflammatory
compounds containing the 1,4-benzodioxine and/or pyrrole system
Y. Harrak,a G. Rosell,a G. Daidone,b,ꢀ S. Plescia,b,ꢀ D. Schillacib,ꢀ and M. D. Pujola,*
a
` `
Laboratori de Quı´mica Farmaceutica (Unitat Associada al CSIC), Facultat de Farmacia, Universitat de Barcelona,
Av. Diagonal 643, E-08028 Barcelona, Spain
`
b
`
Dipartamento di Chimica e Tecnologie Farmaceutiche, Facolta di Farmacia, Universita degli Studi di Palermo, Via Archirafi,
32-90123 Palermo, Italy
Received 15 June 2006; revised 19 April 2007; accepted 27 April 2007
Available online 3 May 2007
Abstract—A series of substituted derivatives containing the 1,4-benzodioxine or pyrrole nucleus are described. All the newly syn-
thesized compounds were examined for their in vitro and in vivo anti-inflammatory activity. Several derivatives, including (S)-2,
14 and 17, showed more anti-inflammatory activity in vivo in these assays (rat paw oedema induced by carrageenan) than the known
classical anti-inflammatory agent ibuprofen, whereas other compounds like 1 were equipotent to ibuprofen. Compound 17 was the
most outstanding derivative because of its remarkable in vivo anti-inflammatory activity. In this paper, we examine and discuss the
structure–activity relationships and anti-inflammatory activities of these compounds.
ꢀ 2007 Elsevier Ltd. All rights reserved.
1. Introduction
native to the corticosteroids and their analogues, which
have many side effects.
Non-steroid anti-inflammatory drugs (NSAIDs) are
among the most widely utilized drugs worldwide, being
the drugs of first choice in the treatment of rheumatoid
disorders, osteoarthritis and also in other inflammatory
diseases and injuries.1 The anti-inflammatory activity is
due to the ability to inhibit the cyclooxygenase (COX)
activity of prostaglandin H synthase, an enzyme which
mediates the production of prostanoids (including pros-
taglandins, protacyclins and thromboxanes) from ara-
chidonic acid. Prostaglandins act as mediator in the
process of inflammation. This mechanism of action
was elicited by Vane.2,3
The cyclooxygenase activity of the enzyme is the site of
action of the non-steroid anti-inflammatory drugs
(NSAIDs).4,5 Selective COX-2 inhibitors have been
developed and marketed based on the presumption that
the postulated mechanism by which the non-selective
NSAIDs cause gastrointestinal ulceration is the inhibi-
tion of the isoenzyme COX-1.6 Recently, based on
FDA data, COX-2 selective-inhibitors are associated
with an increased incidence of serious adverse effects
(cardiovascular disorders) compared to non-selective
anti-inflammatory drugs.7 The largest group of NSAIDs
is represented by the class of arylalkanoic acids, as typ-
ified by their general chemical structure (Fig. 1).
A large number of NSAIDs act as non-selective inhibi-
tors of the COX, inhibiting both the cyclooxygenase-1
(COX-1) and the cyclooxygenase-2 (COX-2) isoen-
zymes. The inhibition of prostanoid biosynthesis is asso-
ciated with side effects such as ulceration and
nephrotoxicity.3 These drugs were developed as an alter-
The aromatic ring system appears to correlate with the
double bond at the 5- and 8-positions of arachidonic
CH3
Ar - (CH2)n - COOH
Ar - CH-COOH
Keywords: Anti-inflammatory activity; Carboxylic acids; 1,4-Benzodi-
oxine; Pyrrole derivatives; AINEs.
Arylalkanoic acids
Arylpropionic acids
*
Corresponding author. Tel.: +34 93 4024534; fax: +34 93 4035941;
e-mail: mdpujol@ub.edu
Fax: +39 91 6236150.
ꢀ
Figure 1. General structure of arylalkylcarboxylic acids.
0968-0896/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2007.04.050

Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
4877
acid. A second area of lipophilicity that is generally not
coplanar with the aromatic or heteroaromatic ring
enhances activity. This second lipophilic area may corre-
spond to the area of the double bond in the 11-position
of arachidonic acid. The heterocyclic ring is believed to
provide the necessary double bond geometry and the
heterocyclic system itself may not be essential for the
anti-inflammatory activity.8
cyanhydrine formation followed by treatment of the
cyanhydrine with potassium bisulfate (KHSO4) at
170 ꢁC. The ester 24 was hydrolysed to the correspond-
ing carboxylic acid 8 by treatment with 2 N NaOH. The
ketone 22 was also converted to the carboxylic acid 9 by
cyanation, followed by treatment with KHSO4 at 100 ꢁC
(Scheme 1). Scheme 2 depicts a route to the synthesis of
the carboxylic acid 10 from the tosylate 26, previously
prepared as described elsewhere.11 The treatment of 26
with potassium cyanide followed by hydrolysis of the ni-
trile with 2 N NaOH provided the desired acid 10 in
acceptable yield.
The anti-inflammatory capacity of aryl acetic and aryl
propionic acids, in which activity is maintained despite
wide variations in the nature of the aryl group, has
prompted recent research. Given the fast and effective
anti-inflammatory activity and the therapeutic interest
reported for certain aryl acetic and aryl propionic acids,
we synthesized several acid compounds as anti-inflam-
matory agents containing heterocyclic nuclei.
We failed to convert the acid 10 to the unsaturated ana-
logue 11, probably because of the easy degradation of
the starting acid in the presence of oxidizing agents.
Therefore, we developed an alternative route from the
2,3-dihydro-1,4-benzodioxine 19 (Scheme 3).
Motivated by the aforementioned findings, and in con-
tinuation of our investigations in this field,9,10 we aimed
to synthesize a novel series of 1,4-benzodioxine deriva-
tives and pyrrole-related compounds for a study of the
structure activity relationships. The heterocyclic system
(1,4-benzodioxine or pyrrole) was selected on the basis
of previous studies realised by us,9,10 and also keeping
in mind the large work in the field of anti-inflammatory
agents reported before.
The 2-bromo-1,4-benzodioxine 28 was prepared from
the 2,3-dihydro-1,4-benzodioxine 19 following the con-
ditions reported previously by Chapleo and co-work-
ers12 Alkylation of the 2-bromo-benzodioxine 28 by
bromoacetic acid, in the presence of t-BuLi in THF at
ꢀ78 ꢁC, gave the acid 11 in acceptable yield. 2,3-Dihy-
dro-1,4-benzodioxine 19 was converted to the carboxylic
acid 12 by formylation of 29 followed by oxidation to
the expected acid 12.13
2. Results and discussion
2.1. Chemistry
The introduction of a pyrrole ring is considered in
Scheme 4. The commercially available aniline 30 was re-
acted with the 2,5-dimethoxytetrahydrofuran in acidic
media giving the pyrrole derivative 31 in good yield.14
2,3-Dihydro-1,4-benzodioxines possessing substituents
on the aryl ring system were conveniently prepared from
commercially available 2,3-dihydro-1,4-benzodioxine
(19) (Scheme 1).
To prepare the carboxylic acid (13–15), the N-substi-
tuted pyrrole 31 was reacted with acetic anhydride
in the presence of BF3Æ(CH3CH2)2O, which gave a
mixture of acetylated compounds (32 and 33) in
acceptable yield. The separated isomers were treated
with sulfur and morpholine under Willgerodt–Kindler
reaction conditions,15 yielding the corresponding
intermediate thioamide, which was hydrolysed to the
corresponding carboxylic acid 14 (34%) or 15 (71%).
The modest yield of acid 14 was due to the formation
of ketoacid 13 as a by-product (50%). The carboxylic
acid 13 was obtained by hydrolysis of the intermediate
ketothioamide formed under Willgerodt–Kindler
conditions.
The carboxylic acid 1 related to the 1,4-benzodioxine
was synthesized from the 2,3-dihydro-1,4-benzodioxine
(19) by acetylation with acetyl chloride followed by
transformation of the resulting ketone to arylacetic acid
under Willgerodt–Kindler reaction conditions.9 We also
prepared the carboxylic acids (R,S)-2, (R)-2, and (S)-2
related to the 1,4-benzodioxine.10
The acylation of 19 using ethyl succinyl chloride yielded
the desired ketoester, which was hydrolysed to the car-
boxylic acid 3. Reduction of the ketoacid 3 with NaBH4
in methanol afforded the lactone 4 in quantitative yield
through reduction followed by cyclization. Reduction
of 3 by NaBH3CN and trifluoroacetic acid or with a
mixture of Zn/HgCl2 in acidic media gave the substi-
tuted butyric acid 5. The acid 5 was transformed into
the desired cyclic ketone 22 with success, using
CF3COOH in dichloromethane. The oxime 6 was ob-
tained by treatment of the ketone 22 with hydroxyl-
amine in pyridine. The corresponding ketoacid 7 was
synthesized from 22 by treatment with LDA followed
by addition of ethyl chloroformate. Next, the intermedi-
ate ester was hydrolysed with 2 N NaOH. The ketone
22 was converted to the nitrile derivative 24 in 48%
overall yield in a two-step sequence consisting of the
An alternative route to the preparation of 13 was the
acylation of 31 with ClCOCOOEt followed by alkaline
hydrolysis (Scheme 4). Other attempts were considered
for the preparation of 14 and 15, which lead to the ex-
pected carboxylic acids but with lower yield.
Scheme 5 depicts the synthesis of the carboxylic acids
(16–18) that possess the fluorophenyl moiety in their
structure. Compounds 16–18 were prepared from the
2-fluorophenylpyrrole 35, as described elsewhere.14
All compounds were obtained as racemic mixtures. Only
the aryl propionic acid 2 was resolved in the correspond-
ing enantiomers.

4878
Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
O
O
CH3
ii
i
O
O
O
O
20
21
COOH
iii
iv
O
19
v
O
O
Br
1. (40 %)
CH3
COOH
vi
O
O
O
(
R
,
S
)-2
)-2
)-2
O
O
O
O
O
vii
O
(R
(
S
COOH
3. (90 %)
4. (99 %)
viii
OH
O
N
O
O
ix
O
O
x
O
O
COOH
CN
22. (87 %)
6. (93 %)
5. (90 %)
xi
xii
O
xiii
O
COOH
O
O
CN
O
O
7. (83 %)
23. (50 %)
O
24. (48 %)
xiv
CN
xv
O
O
COOH
O
O
25. (89 %)
8. (86 %)
xvi
COOH
O
O
9. (75 %)
Scheme 1. Reagents and conditions: (i) CH3COCl/AlCl3; (ii) 1—S8, morpholine, 2—KOH; (iii) NBS/MeOH; (iv) BuLi/BrCH2COOH; (v) LDA/
CH3I/ꢀ78 ꢁC; (vi) 1—EtOCOCH2CH2COCl/TiCl4; 2—NaOH; (vii) 1—NaBH4/MeOH/rt; 2—HCl; (viii) NaCNBH3/CF3COOH (35% yield) or Zn/
HgCl2/HCl (84%); (ix) (CF3CO)2O/CH2Cl2/rt (87% yield); (x) NH2OH/pyridine; (xi) 1—LDA/ꢀ78 ꢁC/EtOCOCl, 2—NaOH/H3O+ (51% yield); (xii)
(CH3CH2)2AlCN/HCl; 2—KHSO4/100 ꢁC; (xiii) 1—(CH3CH2)2AlCN; 2—KHSO4/170 ꢁC; (xiv) NaBH4/MeOH; (xv) NaOH 2 N/reflux; (xvi) NaOH
2 N/reflux.
O
O
O
O
i
CN
COOH
ii
OTs
O
O
26
27. (64 %)
10. (54 %)
Scheme 2. Reagents: (i) KCN/DMSO; (ii) 1—KOH; 2—HCl.
2.2. Biological results and discussion
using the carrageenan rat paw oedema assay and for
their inhibitory activity of the rat liver 3a-hydroxyster-
oid dehydrogenase (3a-HSD). The selected and promis-
ing compounds were also tested in vitro against human
The potential therapeutic activity of these compounds
was assessed both for their anti-inflammatory activity

Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
4879
O
O
Br
COOH
ii
i
O
O
O
O
11. (31 %)
28. (83 %)
O
CHO
O
COOH
iv
19
iii
O
O
12
29
Scheme 3. Reagents and conditions: (i) 1—NBS/CCl4/hm; 2—K+ t-BuOꢀ; (ii) t-BuLi/BrCH2COOH/THF/ꢀ78 ꢁC; (iii) 1—NBS/MeOH; 2—BuLi/
ꢀ78 ꢁC/DMF; (iv) CrO3/t-BuOOH/CH2Cl2.
O
O
O
O
O
O
O
COOH
i
iv
NH2
N
N
30
13
31. (90 %)
ii
O
O
O
O
+
O
N
O
N
32. (50 %)
33. (30 %)
iii
iii
O
O
O
O
O
COOH
COOH
O
N
COOH
+
O
N
N
15. (71 %)
14. (34 %)
13. (50 %)
Scheme 4. Reagents: (i) 2,5-Dimethoxytetrahydrofuran/acetic acid; (ii) acetic anhydride/BF3Æ(CH3CH2)2O; (iii) 1—S8/morpholine; 2—NaOH/
MeOH; (iv) 1—ClCOCOOEt/BF3Æ(CH3CH2)2O; 2—NaOH 2 N.
COX-1 and COX-2 enzymes. Ibuprofen was used as ref-
erence compound for the in vivo and in vitro assays.
The potency and duration of action were compared with
those of the reference compound ibuprofen.22
Mammalian 3a-hydroxysteroid dehydrogenases (3a-
HSDs) are members of the aldo–keto reductase (AKR)
superfamily,16 which has manifold functions (regulation
of steroid hormone levels and carcinogenicity) and thus
includes potential drug targets.17
The highest enzyme inhibition was shown by compound
14, whose IC50 was 5.8 lM, about 17 times higher than
that of ibuprofen. Moreover, this compound had a
stronger anti-inflammatory effect in vivo than ibuprofen.
Likewise, compound 17, with potent anti-3a-HSD enzy-
matic activity (IC50 = 34 lM), showed a higher inhibi-
tory action for the carrageenan-induced oedema than
ibuprofen. In addition, the in vivo anti-inflammatory
activity was sustained after 4 h, whereas ibuprofen activ-
ity decreased quickly.
Moreover, rat liver 3a-HSD can be inhibited by major
classes of non-steroidal anti-inflammatory drugs,18
which has given rise to the rapid spectrophotometer as-
say developed by Penning19 and used in this study.20
We calculated the percentage of inhibition at the
screening concentration of 1000 lM and the IC50 of
3a-HSD enzymatic activity for all tested compounds
(Table 1). Compounds 16, 17 screened at 500 lM and
compounds 8, 18 at 250 lM, owing to the low solubility
or excessive absorbance at 340 nm of their 1000 lM
solutions.
To analyse structure–activity relationships, four struc-
tural components were considered, the nature of the het-
erocycle nucleus, the position of the side chain on the
heterocycle system, the length of the side chain (the dis-
tance between the heterocyclic nucleus and the present
function) and the function of the side chain.
First, regarding the side chain function, the carboxylic
acid confers greater activity both in vivo and in vitro
than the oxime or lactone: while 1 showed % inh = 33
(3 h post-carrageenan), the lactone 4 presented %
inh = 22.6 (3 h post-carrageenan) and the oxime 6 was
Ibuprofen was also tested at 1000 lM for comparison
and its IC50 was 100 lM. The anti-inflammatory activity
of these synthesized compounds in vivo was evaluated
using the carrageenan-induced rat paw oedema assay.21

4880
Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
F
F
F
F
ii
i
O
+
N
N
N
NH2
34
36. (55 %)
35. (90 %)
37. (30 %)
O
iii
iii
F
F
S
N
N
38. X = H, H (33 %)
39. X = O (36 %)
N
O
X
40. (71 %)
N
O
S
iv
iv
F
F
O
N
N
HOOC
17. (96 %)
X
16. X = H, H (95 %)
18. X = O (90 %)
Scheme 5. Reagents and condition: (i) 2,5-Dimethoxytetrahydrofuran/acetic acid; (ii) acetic anhydride/BF3Æ(CH3CH2)2O; (iii) S8/morpholine/140 ꢁC;
(iv) NaOH 2 N.
inactive, on the other hand 1 showed IC50 (lM) = 218, 4
IC50 (lM) >1000 and 6 IC50 (lM) >500 in vitro. The
most surprising result from our SAR analysis may be
the complete lack of anti-inflammatory activity of the
ketoacids 7, 13 and 18.
and also on the aromatic system itself. The compounds
containing the pyrrole ring showed the highest activity
both in the carrageenan-induced oedema test and
in vitro (compounds 14 and 17).
The greater anti-inflammatory activity of 17 in the rat
paw assay and in vitro (% inh (3 h post-carra-
geenan) = 51.9, and IC50 (lM) = 34) in contrast to the
activity shown by the position isomer 16 (% inh (3 h
post-carrageenan) = 23.2), which was less potent than
ibuprofen as an anti-inflammatory agent, indicated the
contribution of the position of substituent on the pyr-
role ring to the anti-inflammatory activity. We also
noted the influence of the N-substituent on the pyrrole
ring. Thus when the N-substituent was 2-fluorophenyl,
the isomer substituted at the C-3 of the aromatic ring
showed higher anti-inflammatory activity than the C-2
substituted isomer, but when the N-substituent was
2,3-dihydro-1,4-benzodioxin-6-yl, the compound substi-
tuted at the C-2 displayed more activity than the corre-
sponding isomer substituted at the C-3 on the pyrrole
ring. We would like to highlight the inversion of activi-
ties depending on the N-substituent and the position of
the substitution on the aromatic ring (compounds 14, 15
and compounds 16, 17).
The influence of the distance between the aromatic het-
erocyclic system and the carboxylic function is marked
and large differences between these compounds were ob-
served especially in vivo.
The compounds 1, 14 and 17 showed greater activity
than ibuprofen according to the results of the carra-
geenan-induced oedema test. In a parallel examination,
compounds 3, 5, 7, 8 and 12, which have more (3 and
5) or less (7, 8 and 12) distance between the carboxylic
acid and the aromatic heterocyclic ring, were the least
active of the series, indicating that the acetic acid chain
confers the highest anti-inflammatory activity.
Likewise, the modest or null anti-inflammatory activity
of compounds 10 and 11, which present the acetic acid
chain linked on the non-aromatic heterocycle moiety,
confirms that the influence of the arylacetic acid frame-
work conditions the anti-inflammatory activity.
The tricyclic carboxylic acid 9, considered a rigid ana-
logue of 1, showed modest anti-inflammatory properties
both in vitro and in vivo. Moreover, the activity of 9
markedly depended on time, peaking at two hours
post-carrageenan.
The introduction of methyl in the side chain of 1 gave
the aryl propionic acid 2, which lowered the anti-inflam-
matory activity both in vitro and in vivo. The results in
Table 1 suggest that the (S)-enantiomer is more potent
than the corresponding (R)-enantiomer. Moreover,
(S)-2 exhibited a long duration of action, and after 5 h
of oral administration (4 h post-carrageenan), it was
3.23 times more active than its enantiomer (R)-2. These
The inhibitory potency depends on the length of the side
chain, on the position of the chain on the aromatic ring

Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
Table 1. In vivo and in vitro anti-inflammatory activity
4881
Compound
Oedema induced by carrageenan (% oedema inh. relative to control)
Inh of 5b-dihydrocortisone
reduction
2 h
Swelling
3 h
4 h
%inh (1 mM)
IC50 (lM)
%inh
Swelling
%inh
33.0
Swelling
%inh
25.6
(a) 25.6 3.7**
(b) 38.2 6.6
(a) 37.2 7.4**
(b) 49.9 5.3
63.8 5.1 (n = 8)
218
O
CO2H
O
1
O
(a) 21.6 2.4*
(b) 27.2 3.6
21.3
37.4
23.7
10.5
(a) 21.6 3.3#
(b) 27.2 6.8
20.6
41.8
13.0
1.5
42.2 2.3 (n = 8)
55 4.2 (n = 6)
43.7 3.1 (n = 8)
61.4 3.9 (n = 6)
>1000
COOH
O
2
CH3
O
(a) 30.3 5.6***
(b) 48.4 2.3
(a) 31.7 7.8***
(b) 54.5 3.0
ffi 300
>1000
209
COOH
CH3
O
(S) -2
O
(a) 31.6 8.8*
(b) 41.4 2.5
(a) 33.5 9.7#
(b) 38.5 3.7
COOH
CH3
O
(R) -2
O
O
(a) 37.6 5.5#
(a) 46.7 6.3#
O
CO2H
3
O
(b) 42.0 12.4
(a) 36.3 5.9*
(b) 46.9 10.7
(b) 47.4 10.5
(a) 44.9 5.5*
(b) 54.8 8.6
O
O
22.6
18.1
46.2 4.2 (n = 6)
>1000
O
4
O
(a) 47.5 9.9
(b) 42.0 12.4
—
(a) 51.1 7.4
(b) 47.4 10.5
—
60.5 3.2 (n = 6)
209
CO2H
OH
O
5
N
—
—
NA
>500
O
O
6
O
O
CO2H
—
—
NA
>1000
O
7
(continued on next page)

4882
Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
Table 1 (continued)
Compound
Oedema induced by carrageenan (% oedema inh. relative to control)
Inh of 5b-dihydrocortisone
reduction
2 h
3 h
4 h
%inh (1 mM)
IC50 (lM)
Swelling
%inh Swelling
%inh Swelling
%inh
—
CO2H
(a) 47.4 6.0
(b) 42.1 6.4
—
(a) 48.6 6.2
(b) 44.3 5.9
67.1 1.0 (n = 5) 100
O
O
8
9
COOH
(a) 21.8 5.4** 24.8
(b) 29.0 6.4
(a) 36.4 8.0**
(b) 42.1 6.4
13.5
(a) 41.1 7.4*
(b) 44.3 5.9
7.2
70.7 2.7 (n = 5) 129
O
O
O
O
(a) 35.8 8.4**
(b) 40.2 4.7
10.9
(a) 34.4 10.2* 0.5
(b) 34.6 2.3
25.4 4.4 (n = 4) >1000
CO2H
10
11
12
O
O
CO2H
(a) 65.3 5.3
(b) 57.2 7.3
—
(a) 66.4 7.4
(b) 54.4 6.1
—
—
—
66.4 4.3 (n = 6) 100
O
O
(a) 42.8 6.7#
(b) 46.9 10.7
8.7
—
(a) 60.8 11.0
(b) 54.8 8.6
54 2.8 (n = 8)
630
COOH
O
O
O
CO2H
(a) 65.3 6.7
(b) 57.2 7.3
(a) 64.1 6.5
(b) 54.4 6.1
67** (n = 5)
70
N
N
N
13
O
O
CO2H
(a) 27.9 3.2*** 49.4
(b) 55.2 8.7
(a) 38.1 3.5** 34.9
(b) 58.6 7.9
75.4 1.8 (n = 5) 5.8
72.5 1.9 (n = 5) 10
71.3 0.8 (n = 6) 18
14
O
O
(1)
(a) 44.7 6.8#
(b) 50.8 3.9
12.0
23.2
(a) 48.8 6.1*
(b) 56.2 5.8
13.2
CO2H
15
F
(a) 42.4 8.9*
(b) 55.2 8.7
(a) 44.9 8.1** 23.4
(b) 58.6 7.9
N
16
CO2H

Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
4883
Table 1 (continued)
Compound
Oedema induced by carrageenan (% oedema inh. relative to control)
Inh of 5b-dihydrocortisone
reduction
2 h
3 h
4 h
%inh (1 mM)
IC50 (lM)
Swelling
%inh
Swelling
%inh
51.9
Swelling
%inh
45.2
(a) 24.4 4.6***
(b) 50.8 3.9
(a) 30.8 6.5**
(b) 56.2 5.8
63.9 4.0 (n = 4)
34
F
CO2H
N
17
F
(1)
NT
NT
27.6 1.0 (n = 4)
>250
N
18
O
CO2H
Ibuprofen
(a) 19.9 4.1*
(b) 24.2 6.7
17.8
(a) 27.1 3.6***
(b) 38.9 6.0
30.3
(a) 34.3 6.9**
(b) 45.1 5.0
23.9
70.5 4.4 (n = 8)
100
(a) Swelling for the dose of 70 mg/kg. (b) Swelling control. (1) Low solubility. NT not tested. NA non-active. Values significantly differ from controls
as indicated: *P < 0.05; **P < 0.01; ***P < 0.001; # does not differ significantly according to unpaired one-tailed Student’s t test.
results are consistent with published data, which show
that the eutomer of the anti-inflammatory a-arylprop-
ionic acids is the (S)-enantiomer. The (S)-2 showed sim-
ilar anti-inflammatory activity to the parent compound
ibuprofen 3 h after carrageenan whereas administration,
the anti-inflammatory activity of (S)-2 after 4 h was 1.76
times higher than that of ibuprofen.
Finally, the biological results of the two enantiomers of
2 showed that the (S)-enantiomer was more potent as
anti-inflammatory compound than the (R)-enantiomer.
3. Experimental
3.1. General methods
The preliminary in vitro results of enzymatic inhibition
of COX-1 and COX-2 for (S)-2 and 14 had shown
non-preference for each one of the COX isoforms, while
16 (COX-2/COX-1 = 3.2) and 17 (COX-2/COX-1 = 4.4)
showed moderate COX-2 selectivity (Table 2).
Melting points were obtained on an MFB-595010 M
Gallenkamp apparatus in open capillary tubes and are
uncorrected. IR spectra were obtained using a FTIR
Perkin-Elmer 1600 Infrared Spectrophotometer. Only
1
noteworthy IR absorptions are listed (cmꢀ1). H and
2.2.1. Conclusion. We have synthesized and evaluated a
series of heterocyclic compounds as potential anti-
inflammatory agents. Based on their structure, we con-
clude that the best aromatic nucleus is the pyrrole with
an N-2-fluorophenyl substituent and an acetic acid sub-
unit on the C-3 such as in compound 17. In the 1,4-ben-
zodioxine derivatives, the anti-inflammatory activity
also depends on the arrangement of the acetic acid
group at the heterocyclic system (compound 1 is more
active than 10 or 11).
13C NMR spectra were recorded on Varian Gemini-
200 (200 and 50.3 MHz, respectively) or Varian Gem-
ini-300 (300 and 75.5 MHz) Instruments using CDCl3
as solvent with tetramethylsilane as internal standard
1
or (CD3)2CO. Other H NMR spectra and heterocorre-
1
lation H–13C (HMQC and HMBC) experiments were
recorded on a Varian VXR-500 (500 MHz). Mass spec-
tra were recorded on a Helwett–Packard 5988-A. Col-
umn chromatography was performed with silica gel (E.
Merck, 70–230 mesh). Reactions were monitored by
TLC using 0.25 mm silica gel F-254 (E. Merck). Micro-
analysis was determined on a Carlo Erba ꢀ1106 ana-
lyser. All reagents were of commercial quality or were
purified before use. Organic solvents were of analytical
grade or were previously purified by standard
procedures.
Table 2. In vitro assays for inhibition of COX-1 and COX-2
Compound
COX-1
a
IC50 (lM)
COX-2
a
IC50 (lM)
Selectivity
COX-1/COX-2
Ibuprofen
1
6.9
>100
13.0
1.9
6.2
>100
16.5
2.2
1.1
—
3.2. 2-(2,3-Dihydro-1,4-benzodioxin-6-yl) acetic acid (1)
(S)-2
14
0.8
0.9
3.2
4.4
To a solution of the bromoderivative 21 (1 g, 3.2 mmol)
in THF (4 mL) was added a solution of n-BuLi in hex-
ane (2.2 mL, 3.52 mmol) at ꢀ78 ꢁC under an argon
atmosphere. The mixture was stirred at ꢀ78 ꢁC for
16
17
19.8
10.6
6.2
2.4
a The result is the average of at least two determinations.

4884
Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
1 h. Then, a solution of bromoacetic acid (486 mg,
3.52 mmol) in freshly distilled THF (2 mL) was added
and the mixture was allowed to warm slowly to 20 ꢁC,
then a solution of saturated NH4Cl was added, and
the resulting mixture was stirred for 20 min. Finally it
was extracted with ether (3· 20 mL) and the aqueous
phase was acidified with 2 N HCl and extracted with
CH2Cl2 (3· 20 mL). Organic layers were dried
(Na2SO4), filtered and concentrated under vacuum,
and the crude product was purified by silica gel column
chromatography. Using a mixture of hexane/ethyl ace-
tate (5:95) as eluent, the carboxylic acid was obtained
as a white solid (40%, yield), mp: 71–73 ꢁC (hexane/ethyl
acetate). IR (KBr) m (cmꢀ1): 2992 (COO–H); 1718
(C@O); 1253 (ArC–O–C); 1066 (C–O–C). 1H NMR
(CDCl3, 500 MHz) d (ppm): 3.51 (s, 2H, C–2H2); 4.22
(s, 4H, CH2–O–); 6.74 (dd, J1 = 8.5, J2 = 2.0 Hz, 1H,
H-70); 6.80 (d, J = 2.0 Hz, 1H, H-50); 6.81 (d,
J = 8.5 Hz, 1H, H-80). 13C NMR (CDCl3, 50.3 MHz) d
(ppm): 40.2 (CH2, C-2); 64.3 (CH2, C-20 y C-30); 117.3
(CH, C-80); 118.2 (CH, C-50); 122.3 (CH, C-70); 126.3
(C, C-60); 142.8 (C, C-40a); 143.4 (C, C-80a); 177.9 (C,
C1 (COOH)). MS (EI), m/z (%): 121 (10%, C7H5O2þ);
149 (100%, C9H9O2þ); 180 (48%); 194 (19%,
C10H10O4þ). Anal. Calcd for C10H10O4: C, 61.85; H,
5.19. Found: C. 61.72; H. 5.41.
organic layer was dried over Na2SO4, filtered off and
evaporated to dryness. The purification on silica gel col-
umn chromatography (hexane/ethyl acetate 70:30 as elu-
ent) of the crude product gives the lactone (99% yield) as
a colourless oil. IR (NaCl) m (cmꢀ1): 1778 (C@O); 1177
(C–O–); 1069 (C–O). 1H NMR (CDCl3, 200 MHz) d
(ppm): 2.15 (m, 1H, CH–); 2.63 (m, 3H, CH2–CH–);
4.26 (s, 4H, CH2–O–); 5.41 (m, 1H, CH–O); 6.86 (m,
3H, Ar). 13C NMR (CDCl3, 50.3 MHz) d (ppm): 29.0
(CH2, C-40); 30.7 (CH2, C-30); 64.2 (CH2, CH2–O–);
81.1 (CH, C-50); 114.6 (CH, C-5); 117.4* (CH, C-7);
118.5* (CH, C-8); 132.3 (C, C-6); 143.6 and 143.8
*
(C, C4a, C8a); 177.0 (C, C@O). Interchangeable. MS
(EI) m/z (relative intensity): 220 (M+, 38).
3.5. 4-(2,3-Dihydro-1,4-benzodioxin-6-yl)butyric acid (5)
A mixture of Zn (1.8 g, 27.5 mmol), Hg2Cl2 (0.18 g,
0.66 mmol) and HCl concd (0.1 mL) in water (3 mL)
was heated under reflux for 5 min. Then, the mixture
was filtered and the solid residue was treated with
H2O (1 mL), HCl concd (2.6 mL), toluene (1.5 mL)
and the ketoacid 3 (620 mg, 2.63 mmol). The reaction
mixture was heated under reflux for 5 h. Then, the mix-
ture was diluted with water (20 mL) and extracted with
ether (3· 20 mL). The combined organic layers were
washed with water (20 mL) and dried (Na2SO4). The
drying agent was filtered off and the filtrate was evapo-
rated to dryness to give yellow oil. The oil was purified
by column chromatography on silica gel using a step-
wise gradient starting with pure hexane up to 50% ethyl
acetate to give a colourless oil (90%, yield). IR (NaCl) m
(cmꢀ1): 3200 (O–H); 1707 (C@O); 1287 (Ar–O); 1069
(C–O–). 1H NMR (CDCl3, 200 MHz) d (ppm): 1.94
(q, J = 7 Hz, 2H, –CH2–); 2.35 (t, J = 7 Hz, 2H, CH2–);
2.59 (t, J = 7 Hz, 2H, –CH2–); 4.22 (s, 4H, CH2–O–);
6.86 (m, 2H, Ar); 6.80 (d, J = 8 Hz, 1H, H-8). 13C
NMR (CDCl3, 50.3 MHz) d (ppm): 26.2 (CH2, CH2–
b); 33.18 (CH2, CH2–a); 34.11 (CH2, CH2–c); 64.28
(CH2, CH2–O–); 116.9 (CH, C-5, C-7); 121.3 (CH, C-
8); 134.4 (C, C-6); 141.7 (C, C-8a); 143.2 (C, C-4a);
180.0 (C, COOH). MS (EI), m/z (%): 222 (M+, 21);
163 (89); 149 (52); 91 (100). Anal. Calcd for C12H14O4:
C, 64.85; H, 6.36. Found: C. 64.67; H. 6.53.
3.3. 4-Oxo-4-(2,3-dihydro-1,4-benzodioxin-6-yl)butyric
acid (3)
A solution of the corresponding intermediate ketoester
(2 g, 8.46 mmol) in 2 N NaOH was heated under reflux
for 2 h. The crude reaction mixture was warmed to room
temperature and extracted with ether (3· 20 mL). The
aqueous layer was acidified with 5 N HCl and extracted
with ether (3· 20 mL). The organic layers were dried
(Na2SO4), filtered off and concentrated under reduced
pressure. The corresponding ketoacid was obtained as
a white solid (90% yield), mp: 137–139 ꢁC (hexane/ethyl
acetate). IR (NaCl) m (cmꢀ1): 3300 (OH); 1702 (COO–);
1682 (CO); 1288 (Ar–O); 1194 (C–O). 1H NMR (CDCl3,
200 MHz) d (ppm): 2.78 (t, J = 6.6 Hz, 2H, CH2–); 3.24
(t, J = 6.6 Hz, 2H, CH2–); 4.31 (m, 4H, CH2–O–); 6.91
(d, J = 8.8 Hz, 1H, H-8); 7.53 (m, 2H, H-5, H-7). 13C
NMR (CDCl3, 50.3 MHz) d (ppm): 29.6 (CH2, CH2–
CO); 32.8 (CH2, CH2–CO); 64.1 and 64.6 (CH2, CH2–
O–); 117.2* (CH, C-7); 117.6* (CH, C-5); 122.1 (CH,
C-8); 130.2 (C, C-6); 143.3 (C, C-4a); 148.1 (C, C-8a);
3.6. (2,3,6,7,8,9-Hexahydrobenzo[g][1,4]benzodioxin-6-yl)-
ketoxime (6)
*
178.6 (C, COO–); 196.3 (C, CO). Interchangeable.
Anal. Calcd for C12H12O5: C, 61.01; H, 5.12. Found:
C. 61.26; H. 5.44.
To a stirred solution of the ketone 22 (200 mg,
0.98 mmol) in 20 mL of dry pyridine was added
136 mg (1.96 mmol) of NH2OH–HCl. The reaction mix-
ture was heated under reflux and stirred for 3 h. After,
the mixture was cooled and the solvent removed. The
obtained residue was diluted with water and extracted
with ether (3· 30 mL). The organic layer was dried over
Na2SO4 and concentrated to dryness affording a crude
product, which was purified by column chromatography
(silica gel, hexane/ethyl acetate 70:30) to give the oxime
as a white solid (199 mg, 0.091 mmol, 93% yield), mp:
188–190 ꢁC (hexane/ethyl acetate). IR (KBr) m (cmꢀ1):
3201 (O–H); 1573 (C@N); 1499 (C@C); 1036 (C–O).
1H NMR (CDCl3, 200 MHz) d (ppm): 1.83 (q,
J = 6.4 Hz, 2H, CH2–); 2.65 (t, J = 6.6 Hz, 2H, CH2–);
3.4. 6-(2-Oxo-tetrahydrofuran-5-yl)-2,3-dihydro-1,4-ben-
zodioxine (4)
NaBH4 (128 mg, 3.4 mmol) was added dropwise to a
solution of the carboxylic acid 3 (200 mg, 0.85 mmol)
in methanol (30 mL) under an argon atmosphere. The
mixture was stirred at room temperature for 4 h. Meth-
anol was removed and the residue was partitioned be-
tween CH2Cl2 and H2O. The two layers were
separated and the aqueous phase was extracted with
dichloromethane after acidification with 5 N HCl. The

Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
4885
2.76 (t, J = 6.6 Hz, 2H, CH2–); 4.25 (s, 4H, H-2 and H-
3); 6.64 (s, 1H, H-10); 7.42 (s, 1H, H-5); 8.59 (s, 1H, OH,
changeable with D2O). 13C NMR (CDCl3+(CD3)2CO,
50.3 MHz) d (ppm): 21.6 (CH2, C-8); 23.6 (CH2, C-9);
29.1 (CH2, C-7); 64.2 (CH2, CH2–O–); 64.6 (CH2,
CH2–O–); 112.5 (CH, C-5); 116.3 (CH, C-10); 123.9
(C, C-5a); 133.6 (C, C-9a); 142.0 (C, C-4a); 144.4 (C,
C-10a); 154.6 (C, C-6). Anal. Calcd for C12H13NO3: C,
65.74; H, 5.98; N, 6.39. Found: C. 63.45; H. 6.16; N,
6.61.
ylic acid as a yellow solid (86% yield), mp: 230–232 ꢁC
(hexane/ethyl acetate). IR (KBr)
(cmꢀ1): 3477
m
(COO–H); 1668 (C@O); 1468 (C@C); 1288 (Ar–O);
1
1072 (C–O). H NMR ((CD3)2CO, 200 MHz) d (ppm):
4.39 (s, 4H, CH2–O–); 7.40 (t, J = 8.4 Hz, 1H, H-8);
7.41 (s, 1H, H-10); 7.93 (d, J = 8.4 Hz, 1H, H-9); 8.20
(d, J = 8.4 Hz, 1H, H-7); 8.60 (s, 1H, H-5). 13C NMR
((CD3)2CO, 50.3 MHz) d (ppm): 61.9 and 61.0 (CH2,
CH2–O–); 108.9 (CH, C-10); 113.3 (CH, C-5); 121.4
(C, C-9a); 122.2 (CH, C-8); 125.2 (C, C-5a); 126.6
(CH, C-7); 127.9 (C, C-6); 129.4 (CH, C-9); 141.8 (C,
C-4a); 143.2 (C, C-10a); 165.5 (C, COOH). Anal. Calcd
for C13H10O4: C, 67.82; H, 4.38. Found: C. 67.94; H.
4.56.
3.7. (6-Oxo-2,3,6,7,8,9-hexahydrobenzo[g][1,4]benzodi-
oxin-7-yl) carboxylic acid (7)
To a cooled solution (ꢀ78 ꢁC) of the ketone 22 (500 mg,
2.45 mmol) in anhydrous THF (3 mL) under an argon
atmosphere, a 2 M solution of LDA in hexane
(2.5 mL, 5 mmol) was added dropwise with stirring over
a 15-min period. The mixture was slowly stirred at
ꢀ78 ꢁC for 3 h, and ethyl chloroformate (0.7 mL,
7.35 mmol) was slowly added with stirring. The solution
was allowed to warm to room temperature (20 ꢁC) over-
night and then was neutralized with saturated aqueous
ammonium chloride solution (5 mL). The THF layer
was separated and the aqueous alkaline phase was acid-
ified with 2 N HCl, and the crude of reaction was ex-
tracted with ether (3· 20 mL). The extracts were dried
(Na2SO4) and evaporated under reduced pressure to
give brown oil, which was purified by silica gel chroma-
tography using hexane/ethyl acetate (80:20) as eluent.
The ester obtained was treated with 8% NaOH
(20 mL) and stirred at room temperature for 24 h. Next,
the mixture was acidified with 5 N HCl and extracted
with CH2Cl2 (3· 30 mL). The extracts were dried
(Na2SO4), filtered and evaporated under reduced pres-
sure to give a white solid, which was purified by column
chromatography (ethyl acetate) to give 7 (177 mg,
0.71 mmol, 83% yield) as a white solid, mp: 184–
186 ꢁC (hexane/ethyl acetate). IR (KBr) m (cmꢀ1): 3300
(O–H); 1719 (C@O); 1698 (C@O); 1506 (C@C); 1299
3.9. 2,3,6,7,8,9-Hexahydrobenzo[g][1,4]benzodioxin-6-yl
carboxylic acid (9)
A solution of the nitrile 25 (200 mg, 0.928 mmol) in 2 N
NaOH (40 mL) was heated at reflux temperature for
14 h. The solution was cooled to 25 ꢁC, acidified with
5 N hydrochloric acid and extracted with ether
(80 mL). The organic phase was dried, filtered off and
evaporated under reduced pressure to give a reddish
solid which was purified by silica gel column chromatog-
raphy, eluting with hexane/ethyl acetate 30:70. The
acid 9 was obtained as a white solid (163 mg, 0.69 mmol)
in 75% yield, mp 137–139 ꢁC (hexane /ethyl acetate).
IR (KBr) m (cmꢀ1): 3290 (O–H); 1704 (C@O); 1507
(C@C); 1251 (Ar–O); 1065 (C–O). 1H NMR
((CD3)2CO, 200 MHz) d (ppm): 1.61 (m, 2H, CH2–);
1.71 (m, 2H, CH2–); 1.82 (m, 2H, CH2–); 3.48 (t,
J = 6 Hz, CH–); 6.40 (s, 1H, Ar); 6.58 (s, 1H, Ar). 13C
NMR ((CD3)2CO, 50.3 MHz) d (ppm): 18.1 (CH2,
C-8); 24.0 (CH2, C-7); 26.5 (CH2, C-9); 41.1 (CH, C-
6); 61.7 and 61.8 (CH2, CH2–O–); 114.1 (C, C-5);
114.7 (CH, C-10); 123.7 (C, C-5a); 127.3 (C, C-9a);
139.1 (C, C-4a and C-10a); 172.7 (C, C@O). Anal. Calcd
for C13H13O4: C, 66.66; H, 6.02. Found: C. 66.47; H.
6.21.
1
(Ar–O); 1065 (C–O). H NMR (CD3OD, 200 MHz) d
(ppm): 2.00 (dt, J = 6 Hz, 2H, CH2–); 2.93
(t, J = 6 Hz, 2H, CH2–); 3.28 (t, J = 6 Hz, 1H, CH2–);
4.24 and 4.25 (s, 4H, H-2 and H-3); 6.70 (s, 1H, H-
10); 7.45 (s, 1H, H-5). 13C NMR (CD3OD, 50.3 MHz)
d (ppm): 33.3 (CH2, C-8); 34.1 (CH2, C-9); 54.2 (CH2,
C-7); 66.6 (CH2, CH2–O–); 67.5 (CH2, CH2–O–); 121.9
(CH, C-5); 123.1 (CH, C-10); 124.6 (C, C-5a); 140.0
(C, C-9a); 144.3 (C, C-4a); 149.7 (C, C-10a); 172.3 (C,
COOH). Anal. Calcd for C13H12O5: C, 62.90; H, 4.87.
Found: C. 63.18; H. 5.15.
3.10. 2-(2,3-Dihydro-1,4-benzodioxin-2-yl) acetic acid
(10)
A solution of the nitrile 27 (400 mg, 2.3 mmol) in 2N
NaOH (50 mL) was heated under reflux temperature
for 12 h. The solution was cooled to 25 ꢁC, was acidified
with 5 N hydrochloric acid and extracted with ether (3·
20 mL). The organic phase was dried, filtered off and
evaporated under reduced pressure to give reddish oil.
Treatment of this oil with hexane/ethyl acetate gave
the white solid 10 (240 mg, 1.24 mmol) in 54%, mp:
89–91 ꢁC. IR (KBr) m (cmꢀ1): 3358 (COO–H); 1705
3.8. 2,3-Dihydrobenzo[g][1,4]benzodioxin-6-yl carboxylic
acid (8)
1
(C@O); 1203 (Ar–O); 1073 (C–O). H NMR (CDCl3,
200 MHz) d (ppm): 2,71 (dd, J1 = 16.0, J2 = 6 Hz, 1H,
H-2); 2.85 (dd, J1 = 16.0, J2 = 6.8 Hz, 1H, H-2); 4.02
A solution of the nitrile 24 (150 mg, 0.71 mmol) in
50 mL of 2 N NaOH was heated under reflux for 16 h.
The solution was cooled (at 0 ꢁC) and acidified with
2 N HCl, and the mixture was extracted with ether (3·
20 mL). The organic layer was dried (Na2SO4), filtered
off and evaporated to dryness. The residue was purified
by column chromatography on silica gel using hexane/
ethyl acetate 60:40 as eluent to give the desired carbox-
(dd, J1 = 11.3, J2 = 6.6 Hz, 1H, H ꢀ 30 ); 4.32 (dd,
ax
J1 = 11.3, J2 = 2.2 Hz, 1H, H ꢀ 30 ); 4.62 (m, 1H, H-
ec
20); 6.87 (m, 4H, Ar and COOH). 13C NMR (CDCl3,
50.3 MHz) d (ppm): 35.9 (CH2, C-2); 66.8 (CH2, C-30);
69.1 (CH, CH-20); 117.2 (CH, C-50); 117.5 (CH, C-80);
121.6 (CH, C-60) y 121.8 (CH, C-70); 142.7 (C, C40a);
142.8 (C, C-80a); 175.9 (C, C1–COOH). Anal. Calcd

4886
Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
for C10H10O4: C, 61.85; H, 5.19. Found: C, 61.72; H,
5.38.
obtained was diluted with ice-water and the solution was
extracted with ether (3· 30 mL). The organic layers were
dried (Na2SO4), filtered off and concentrated under re-
duced pressure to give the corresponding arylacetic acid.
3.11. 2-(1,4-Benzodioxin-2-yl) acetic acid (11)
A 1.6 M solution of butyl lithium in hexane (1.76 mL,
2.90 mmol) under argon atmosphere was added to a
3.14. 2-[N-(2,3-Dihydro-1,4-benzodioxin-6-yl)pyrrol-2-yl]-
2-oxoacetic acid (13). 2-[N-(2-Fluorophenyl) pyrrol-2-yl]-2-
oxoacetic acid (18)
solution
of
2-bromo-1,4-benzodioxine
(500 mg,
2.35 mmol) in anhydrous THF (4 mL) cooled to
ꢀ78 ꢁC. The mixture was stirred for 1 h at ꢀ78 ꢁC. Then
a solution of 2-bromoacetic acid (486 mg, 3.52 mmol) in
THF (2 mL) was added at ꢀ78 ꢁC and stirred for an-
other half hour. The resulting mixture was allowed to
warm slowly to room temperature. The reaction was
quenched with saturated NH4Cl solution (2 mL) and
the obtained carboxylic acid was extracted with ether
(3· 20 ml). The aqueous layer was acidified with 2 N
HCl (5 mL) and extracted with CH2Cl2 (3· 20 mL).
The last organic layer was dried (Na2SO4), filtered off
and evaporated to dryness. A purification on silica gel
column chromatography (hexane/ethyl acetate 5:95 as
eluent) gave the 2-(1,4-benzodioxin-2-yl) acetic acid as
a white solid (38%, yield), mp: 129–130 ꢁC (hexane/ethyl
acetate). 1H NMR (CD3COCD3, 200 MHz) d (ppm):
2.94 (s, 2H, CH2–); 5.98 (s, 1H, H-3); 6,57 (m, 2H, H-
5, H-8); 6,73 (m, 2H, H-6 and H-7). 13C NMR
(CD3COCD3, 50.3 MHz) d (ppm): 35.5 (CH2, CH2–
COOH); 117.1* (CH, C-5); 117.3* (CH, C-8); 125.4#
(CH, C-3); 125.5# (CH, C-6); 125.6# (CH, C-7); 133.9
(C, C-2); 143.2 and 143.8 (C, C-4a and C-8a); 170.8
(C, C (COOH)). MS (EI), m/z (%): 192 (M, 3); 147
(M-45, 38); 69 (M-123, 100). Anal. Calcd for C10H8O4:
The carboxylic acids 13 and 18 were obtained by hydro-
lysis of the corresponding ketothioamide, by-product
formed on the Willgerodt reaction from the methylke-
tone 32 and 36, respectively. From the methylketone
32 and following the procedure for the hydrolysis de-
scribed above was obtained 13 (130 mg, 0.47 mmol,
94% yield) as a white solid, mp: 162–164 ꢁC (hexane/
ethyl acetate). IR (KBr) m (cmꢀ1): 3245 (OH); 1769
(C@O); 1645 (C@O); 1345 (Ar–O); 1063 (C–O). 1H
NMR ((CD3)2CO, 200 MHz) d (ppm): 4.17 (s, 2H,
CH2–O); 6.26 (s, 1H, H-4 pyrrole); 6.70 (m, 3H, H-7
and H-8 pyrrole); 7.20 (m, 1H, H-3 pyrrole); 7.41 (m,
1H, H-5 pyrrole). 13C NMR ((CD3)2CO, 50.3 MHz) d
(ppm): 65.6 (CH2, CH2–O); 111.3 (CH, C-30 pyrrole);
111.7 (CH, C-40 pyrrole); 118.1 (CH, C-5); 120.2 (CH,
C-7); 126.7 (CH, C-8); 128.1 (C, C-20 pyrrole); 133.2
(C, C-6); 135.8 (CH, C-5 pyrrole); 142.5 (C, C-4a);
142.9 (C, C-8a); 164.2 (C, COOH); 176.1 (C, C@O).
Anal. Calcd for C14H11NO5: C, 61.54; H, 4.06; N,
5.13. Found: C, 61.69; H, 4.36; N, 5.29.
Compound 18 was obtained by hydrolysis of the inter-
mediate ketothioamide following the general method de-
scribed as a white solid (140 mg, 0.60 mmol, 90% yield),
mp: 129–131 ꢁC (hexane/ethyl acetate). IR (KBr) m
(cmꢀ1): 2923 (OH); 1735 (C@O); 1620 (C@O); 1504
C, 62.50; H, 4.20. Found: C, 62.46; H, 4.34. and#
*
Interchangeables.
1
3.12. (2,3-Dihydro-1,4-benzodioxin-6-yl) carboxylic acid
(12)
(C@C); 1047 (C–O). H NMR ((CD3)2CO, 200 MHz)
d (ppm): 6.51 (s, 1H, H-4 pyrrole); 7.19 (m, 1H, H-5 pyr-
role); 7.30 (m, 4H, Ar); 8.16 (m, 1H, H-3 pyrrole). 8.92
(br s, 1H, COOH, exchanges with D2O). 13C NMR
((CD3)2CO, 50.3 MHz) d (ppm): 112.5 (CH, C-3 pyr-
role); 117.1 (CH, J = 20 Hz, C-30); 125.8 (CH, C-50);
126.6 (CH, C-4 pyrrole); 129.1 (C, C-2 pyrrole); 129.6
(CH, C-5 pyrrole); 129.7 (C, C-10); 131.3 (CH,
J = 8.2 Hz, C-40); 135.5 (CH, C-60); 158.6 (C,
J = 249 Hz, C-20); 164.4 (C, COOH); 175.0 (C, C@O).
Anal. Calcd for C12H8NO3: C, 61.81; H, 3.46; N, 6.01.
Found: C, 61.57; H, 3.58; N, 6.15.
To a solution of aldehyde 29 (1 g, 6.1 mmol) in CH2Cl2
(25 mL) were added under hard stirring CrO3 (800 mg,
8 mmol) and t-BuOOH (721 mg, 8 mmol), and the
resulting mixture was stirred at room temperature for
24 h. The crude residue was treated with concentrated
NH4OH. The aqueous phase was separated, treated with
2 N HCl and extracted with ether (3· 20 mL). The or-
ganic layer was dried over Na2SO4 and concentrated
to dryness to give the carboxylic acid 12 as a colourless
oil (920 mg, 5.1 mmol, 84% yield). IR (KBr) m (cmꢀ1):
1
3303 (COO–H); 1712 (C@O); 1235 (Ar–O). H NMR
3.15. 2-[N-(2,3-Dihydro-1,4-benzodioxin-6-yl)-pyrrol-2-
yl] acetic acid (14)
(CDCl3, 200 MHz) d (ppm): 4.30 (m, 4H, CH2–O);
6.91 (d, J = 9.2 Hz, 1H, H-8); 7.63 (m, 2H, H-5, H-7).
13C NMR (CDCl3, 50.3 MHz) d (ppm): 64.0 (CH2,
CH2–O); 64.6 (CH2, CH2–O); 117.2 (CH, C-5); 119.6
(CH, C-7); 122.4 (CH, C-6); 124.1 (CH, C-8); 143.1
(C, C-4a); 148.4 (C, C-8a); 171.3 (C, CO).
Following the general procedure and starting from the
corresponding thioamide (100 mg, 0.3 mmol) derivative
the acetic acid 14 was obtained as a white solid (90%
yield), mp: 97–99 ꢁC (hexane/ethyl acetate). IR (KBr) m
(cmꢀ1): 3230 (OH); 1712 (C@O); 1250 (Ar–O); 1163
1
3.13. Hydrolysis of the thioacetamides: general procedure
(C–O). H NMR (CDCl3, 200 MHz) d (ppm): 3.60 (s,
2H, CH2–Ar); 4.27 (s, 4H, CH2–O–); 6.21 (m, 2H, H-3
and H-4 pyrrole); 6.74 (m, 1H, H-5 pyrrole); 6.82 (m,
3H, Ar). 13C NMR (CDCl3, 50.3 MHz) d (ppm): 32.3
(CH2, CH2–Ar); 64.3 (CH2, CH2–O–); 108.2 (CH, C-3
pyrrole); 109.5 (CH, C-4 pyrrole); 115.2 (CH, C-50);
117.4 (CH, C-70); 119.5 (CH, C-80); 122.9 (CH, C-5
A mixture of the intermediate thioamide (0.30 mmol) in
60 mL of a mixture (1:1) of aqueous 8% NaOH solution
and methanol was stirred under reflux for 4 h. The
cooled mixture was acidified with diluted HCl solution
and the solvent was removed under vacuum. The residue

Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
4887
pyrrole); 124.9 (C, C-2 pyrrole); 133.0 (C, C-60); 143.1
(C, C-80a); 143.5 (C, C-40a); 176.6 (C, COOH). Anal.
Calcd for C14H13NO4: C, 64.86; H, 5.05; N, 5.40.
Found: C, 64.71; H. 5.26; N, 5.57.
154.1 (C, J = 250 Hz, C-20); 176.9 (C, COOH). Anal.
Calcd for C12H10FNO2: C, 65.75; H, 4.60; N, 6.39.
Found: C, 65.56; H, 4.77; N, 6.67.
3.19. 6-Oxo-2,3,6,7,8,9-hexahydrobenzo[g][1,4]benzodi-
oxine (22)
3.16. 2-(N-(2,3-Dihydro-1,4-benzodioxin-6-yl)pyrrol-3-yl)
acetic acid (15)
To a stirring solution of the butyric acid 5 (2.5 g,
11.25 mmol) in dry CH2Cl2 (30 mL) cooled to 0 ꢁC
was added (CF3CO)2O (2 mL). The mixture was stirred
at room temperature for 6 h. The crude of reaction was
diluted with water and extracted with CH2Cl2. The
organic layers were washed with H2O, dried over
Na2SO4 and evaporated to dryness. A purification on
silica gel column chromatography (hexane/ethyl acetate
90:10 as eluent) gave the ketone 22 (87%, yield), mp:
105–106 ꢁC (hexane/ethyl acetate). IR (KBr) m (cmꢀ1):
1762 (C@O); 1294 (Ar–O); 1064 (C–O–). 1H NMR
(CDCl3, 200 MHz) d (ppm): 2.08 (qt, J = 6.8 Hz, 2H,
C-8H2); 2.55 (t, J = 6.8 Hz, 2H, C-7H2); 2.84 (t,
J = 6.8 Hz, 2H, C-9H2); 4.27 (m, 4H, CH2–O–); 6.70
(s, 1H, H-10); 7.55 (s, 1H, H-5). 13C NMR (CDCl3,
50.3 MHz) d (ppm): 23.5 (CH2, C-9); 29.0 (CH2, C-8);
38.7 (CH2, C-7); 63.9 (CH2, CH2–O); 64.7 (CH2,
CH2–O); 115.7 (CH, C-5); 116.3 (CH, C-10); 126.6 (C,
C-5a); 138.7 (C, C-9a); 142.3 (C, C-4a); 148.1 (C,
C-10a); 196.9 (C, CO). MS (EI) m/z (relative intensity):
204 (M+, 68).
The preparation of the acetic acid 15 (89%) was carried
out from the corresponding thioamide (300 mg,
0.87 mmol) following the general procedure described
above. The acid 15 was obtained as a white solid, mp:
117–119 ꢁC (hexane/ethyl acetate). IR (KBr) m (cmꢀ1):
1
3217 (OH); 1702 (C@O); 1223 (Ar–O); 1125 (C–O). H
NMR ((CD3)2CO, 200 MHz) d (ppm): 3.50 (s, 2H,
CH2–Ar); 4.29 (s, 4H, CH2–O–); 6.31 (m, 1H, H-40 pyr-
role); 6.94 (m, 4H, Ar); 7.08 (m, 1H, H-20 pyrrole). 13C
NMR ((CD3)2CO, 50.3 MHz) d (ppm): 32.7 (CH2, CH2–
Ar); 65.7 (CH2, CH2–O–); 65.9 (CH2, CH2–O); 110.3
(CH, C-40 pyrrole); 112.5 (CH, C-5); 114.1 (CH, C-8);
116.5 (C, C-30 pyrrole); 119.1* (CH, C-20 pyrrole);
119.4* (CH, C-50 pyrrole); 120.4 (CH, C-7); 136.5 (C,
C-6); 143.0 (C, C-4a); 145.6 (C, C-8a); 173.9 (C,
COOH). Anal. Calcd for C14H13NO4: C, 64.86; H,
5.05; N, 5.40. Found: C, 64.73; H, 5.18; N, 5.59.
3.17. 2-(N-(2-Fluorophenyl)pyrrol-2-yl) acetic acid (16)
Taking as starting material the thioamide (200 mg,
0.65 mmol) and following the general procedure the car-
boxylic acid 16 was obtained as a white solid with 95%
yield, mp: 92–94 ꢁC (hexane/ethyl acetate). IR (KBr) m
(cmꢀ1): 2920 (OH); 1708 (C@O); 1311 (Ar–N); 1170
(C–O); 763 (C–F). 1H NMR (CDCl3, 200 MHz) d
(ppm): 3.54 (s, 2H, CH2–Ar); 6.28 (m, 2H, H-3 and H-
4 pyrrole); 6.75 (m, 1H, H-5 pyrrole); 7.23 (m, 4H, H-
30, H-40, H-50, H-60). 13C NMR (CDCl3, 50.3 MHz) d
(ppm): 32.0 (CH2, CH2–Ar); 108.9 (CH, C-3 pyrrole);
109.9 (CH, C-4 pyrrole); 116.5 (CH, J = 20, C-30);
123.2 (CH, C-60); 124.6 (CH, C-50); 124.8 (C, C-2 pyr-
role); 127.1 (C, J = 12,8 Hz, C-10); 129.4 (CH, C-5 pyr-
role); 129.7 (CH, J = 7.2 Hz, C-40); 157.3 (C,
J = 250.8 Hz, C-2); 176.6 (C, COOH). Anal. Calcd for
C12H10FNO2: C, 65.75; H, 4.60; N, 6.39. Found: C,
65.89; H, 4.71; N, 6.63.
3.20. 6-Cyano-2,3,8,9-tetrahydrobenzo[g][1,4]benzodiox-
ine (23)
Under an argon atmosphere, a solution of the ketone 22
(400 mg, 1.95 mmol) in toluene (10 mL) was cooled
(ꢀ15 ꢁC) and a 1 M solution of (Et)2AlCN in toluene
was dropwise added. The resulting mixture was stirred
at ꢀ15 ꢁC for 2 h. Then, a mixture of MeOH/HCl concd
(10 mL/5 mL) was added and the mixture was stirred at
room temperature for 1 h. The crude product was ex-
tracted with CH2Cl2 (3· 20 mL). The organic layer
was dried over Na2SO4, filtered off and evaporated to
dryness. The residue obtained is a mixture of the desired
compound 23 and starting material.
A mixture of the crude product (400 mg) and KHSO4
(200 mg) was heated at 100 ꢁC for 1 h. The residue
was washed with water and extracted with CH2Cl2
(3· 20 mL). The organic layer was dried over Na2SO4,
filtered off and the solvent evaporated to dryness. The
brown oil obtained was purified by column chromatog-
raphy (hexane/ethyl acetate 85:15) to give 23 as yellow
oil (50%, yield), mp: 94–96 ꢁC (hexane/ethyl acetate).
IR (KBr) m (cmꢀ1): 2219 (CN); 1503 (C@C); 1287 (Ar–
3.18. 2-(N-(2-Fluorophenyl)pyrrol-3-yl) acetic acid (17)
The preparation of the acetic acid 17 was carried out
from the corresponding thioamide (200 mg, 1.11 mmol)
following the general procedure for the hydrolysis of
thiocarboxamides. The carboxylic acid was obtained as
a white solid, 96% yield, mp: 103–105 ꢁC (hexane/ethyl
acetate). IR (KBr) m (cmꢀ1): 2965 (OH); 1712 (C@O);
1291 (Ar–N); 1143 (C–O); 776 (C–F). 1H NMR (CDCl3,
200 MHz) d (ppm): 3.60 (s, 2H, CH2–Ar); 6.31 (t,
J = 2.2 Hz, 1H, H-4 pyrrole); 6.97 (t, J = 2.2 Hz, 2H,
H-2 and H-5H pyrrole); 7.17 (m, 3H, Ar); 7.28 (m,
1H, Ar). 13C NMR (CDCl3, 50.3 MHz) d (ppm): 32.8
(CH2, CH2–Ar); 110.9 (CH, C-4 pyrrole); 116.4 (C, C-
3 pyrrole); 116,9 (CH, J = 20.6 Hz, C-30); 120.1 (CH,
C-60); 121.5 (CH, C-50); 124.6 (CH, C-2 and C-5 pyr-
role); 127.0 (CH, J = 7,8 Hz, C-40); 127.2 (C, C-10);
1
O); 1066 (C–O). H NMR (CDCl3, 200 MHz) d (ppm):
2.44 (m, 2H, CH2); 2.72 (m, 2H, CH2); 4.23 (m, 4H,
CH2–O–); 6.64 (s, 1H, H-10); 6.75 (t, J = 5 Hz, 1H, H-
7); 6.97 (s, 1H, H-5). 13C NMR (CDCl3, 50.3 MHz) d
(ppm): 23.9 (CH2, C-8); 25.6 (CH2, C-9); 64.3 y 64.6
(CH2, CH2–O–); 113.6 (C, C-6); 113.9 (CH, C-5);
116.8 (CH, C-10); 117.2 (C, CN); 122.2 (C, C-5a);
127.5 (C, C-9a); 141.8 (CH, C-7); 142.2 (C, C-4a);
143.9 (C, C-10a). MS (EI) m/z (relative intensity): 213
(M+, 42).

4888
Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
3.21. 6-Cyano-2,3-dihydrobenzo[g][1,4]benzodioxine (24)
The crude product was purified by silica gel column
chromatography using hexane/ethyl acetate as eluent.
A solution of the ketone 22 (400 mg, 1.95 mmol) in tol-
uene (10 mL) was cooled (ꢀ15 ꢁC) and a 1 M solution of
(Et)2AlCN in toluene was added. The resulting mixture
was stirred at ꢀ15 ꢁC for 2 h. After hydrolysis with
MeOH/HCl concd (10 mL/5 mL), the extracted nitrile
was stirred at room temperature for 1 h. The obtained
residue was extracted with CH2Cl2 (3· 20 mL). The or-
ganic layers were dried (Na2SO4), filtered and evapo-
rated to dryness. The crude product is a mixture of the
desired compound and starting compound. Then,
KHSO4 (200 mg) was added to the crude product, and
the resulting mixture was heated at 170 ꢁC for 5 h. The
mixture was washed with water and extracted with
CH2Cl2 (3· 20 mL). The organic layers were dried over
Na2SO4, filtered off and evaporated to dryness. The
crude product was subjected to silica gel column chro-
matography (hexane/ethyl acetate (80:20) as an eluent).
Thus 24 was obtained as a white solid (48% yield),
mp: 157–159 ꢁC (hexane/ethyl acetate). 1H NMR
((CD3)2CO, 200 MHz) d (ppm): 4.39 (m, 4H, CH2–O–);
7.36 (m, 2H, C-8H, H-10); 7.65 (s, 1H, H-5); 7.73 (d,
J = 8.4 Hz, 1H, H-9); 7.86 (d, J = 8.4 Hz, 1H, H-7).
MS (EI) m/z (relative intensity): 211 (M+, 12).
3.24. Preparation of the 6-(2-acetylpyrrol-1-yl)-2,3-dihy-
dro-1,4-benzodioxine (32) and 6-(3-acetylpyrrol-1-yl)-2,3-
dihydro-1,4-benzodioxine (33)
Starting from 6-(pyrrol-1-yl)-2,3-dihydro-1,4-benzodi-
oxine 31 (1 g, 5 mmol) and following the general
procedure described above for the preparation of meth-
ylketones were obtained 32 (604 mg, 2.48 mmol, yield
50%) and 33 (363 mg, 1.49 mmol, yield 30%). 6-(2-Acet-
ylpyrrol-1-yl)-2,3-dihydro-1,4-benzodioxine (32), mp:
111–113 ꢁC (hexane/ethyl acetate). IR (KBr) m (cmꢀ1):
1662 (C@O); 1507 (C@C); 1226 (Ar–O); 1064 (C–O).
1H NMR (CDCl3, 200 MHz) d (ppm): 2.40 (s, 3H,
CH3); 4.26 (s, 4H, CH2–O–); 6.24 (dd, J1 = 4,
J2 = 2.4 Hz, 1H, H-40 pyrrole); 6.78 (m, 3H, Ar); 6.88
(m, 1H, H-30 pyrrole); 6.90 (dd, J1 = 2.2, J2 = 1.4 Hz,
1H, H-50 pyrrole). 13C NMR (CDCl3, 50.3 MHz) d
(ppm): 64.3 (CH2, CH2–O); 108.9 (CH, C-40 pyrrole);
115.2 (CH, C-7); 116.9 (CH, C-5); 119.2 (CH. C-8);
120.2 (CH, C-30 pyrrole); 131.2 (CH, C-50 pyrrole);
131.6 (C, C-20 pyrrole); 134.3 (C, C-6); 143,1 (C, C-4a,
C-8a); 186,9 (C, C@O). Anal. Calcd for C14H13NO3:
C, 69.12; H, 5.39; N, 5.76. Found: C. 69.42; H. 5.76;
N, 5.97. 6-(3-Acetylpyrrol-1-yl)-2,3-dihydro-1,4-benzo-
dioxine (33). IR (NaCl) m (cmꢀ1): 1659 (C@O); 1503
3.22. 6-Cyano-2,3,6,7,8,9-hexahydrobenzo[g][1,4]benzo-
dioxine (25)
1
(C@C); 1231 (Ar–O); 1045 (C–O). H NMR (CDCl3,
NaBH4 (227 mg, 6 mmol) was added slowly to a solu-
tion of the nitrile derivative 23 (300 mg, 1.40 mmol) in
methanol (30 mL), under an argon atmosphere. The
resulting mixture was stirred at room temperature for
24 h. The solvent was removed, and the residue was par-
titioned between CH2Cl2 and H2O. The two layers were
separated and the aqueous layer was extracted with
dichloromethane. The organic layer was dried and the
solvent removed. The crude product was purified by col-
umn chromatography (silica gel, hexane/ethyl acetate
50:50 as eluent) to give 25 (89% yield) as a white solid,
mp: 96–97 ꢁC (hexane/ethyl acetate). IR (KBr) m
(cmꢀ1): 2223 (CN); 1504 (C@C); 1295 (Ar–O); 1067
200 MHz) d (ppm): 2.43 (s, 3H, CH3); 4.27 (s, 4H,
CH2–O); 6.70 (m, 1H, H-40 pyrrole); 6.90 (m, 4H, H-50
pyrrole, H-5, H-7, H-8); 7.54 (t, J = 2.2 Hz, 1H, H-20
pyrrole). 13C NMR (CDCl3, 50.3 MHz) d (ppm): 64.3
(CH2, CH2–O); 64.5 (CH2, CH2–O); 110.3* (CH, C-40
pyrrole); 110.6* (CH, C-50 pyrrole); 114.2 (CH, C-8);
117.9 (CH, C-5); 121.5 (CH, C-7); 124.3 (CH, C-20 pyr-
role); 127.2 (C, C-30 pyrrole); 133.6 (C, C-6); 142.6 (C,
*
C-4a); 143.9 (C, C-8a); 193.4 (C, C@O). Interchange-
able. Anal. Calcd for C14H13NO3: C, 69.12; H, 5.39;
N, 5.76. Found: C. 69.49; H. 5.12; N, 5.38.
3.25. Preparation of the N-(2-fluorophenyl)-2-acetylpyr-
role (36) and N-(2-fluorophenyl)-3-acetylpyrrole (37)
1
(C–O). H NMR (CDCl3, 200 MHz) d (ppm): 1.60 (m,
2H, CH2–); 2.10 (m, 2H, CH2–); 2.69 (m, 2H, CH2–);
3.67 (t, J = 6 Hz, CH–); 4.05 (s, 4H, CH2–O); 6.60 (s,
1H, Ar); 6.85 (s, 1H, Ar). 13C NMR (CDCl3,
50.3 MHz) d (ppm): 20.9 (CH2, C-8); 27.4 (CH2, C-7);
27.8 (CH2, C-9); 30.2 (CH, C-6); 64.3 and 64.6 (CH2,
CH2–O–); 116.9 (C, C-5); 117.5 (CH, C-10); 121.8 (C,
CN); 122.4 (C,C-5a); 129.3 (C, C-9a); 142.1 (C, C-4a);
143.3 (C, C-10a).
Starting from the N-(2-fluorophenyl)pyrrole 35 (806 mg,
5 mmol) and following the general procedure described
above, the 2-substituted pyrrole 36 559 mg (55%) and
the 3-substituted pyrrole 37 305 mg (30%) were ob-
tained. N-(2-Fluorophenyl-2-acetylpyrrole) (36), mp:
118–120 ꢁC (hexane/ethyl acetate). IR (KBr) m (cmꢀ1):
1653 (C@O); 1505 (C@C); 1214 (Ar–O); 1024 (C–O).
1H NMR (CDCl3, 200 MHz) d (ppm): 2.43 (s, 3H,
CH3); 6.35 (m, 1H, H-4 pyrrole); 6.93 (m, 1H, H-5 pyr-
role); 7.08 (m, 1H, H-3 pyrrole); 7.22 (m, 4H, H-30, H-40,
H-50, H-60). 13C NMR (CDCl3, 50.3 MHz) d (ppm): 26.9
(CH3, CH3–); 109.7 (CH, C-3); 115.8 (CH, J = 22 Hz, C-
30); 119,8 (CH, C-4); 124.1 (CH, J = 8 Hz, C-40); 127.8
(CH, C-5); 129.0 (C, C-10); 129.2 (CH, J = 8 Hz, C-60);
130.6 (CH, C-50); 130.1 (C, C-2); 157,0 (C, J = 250 Hz,
C-20); 187,2 (C, C@O). Anal. Calcd for C12H10FNO:
C, 70.93; H, 4.97; N, 6.89. Found: C. 70.65; H. 5.23;
N, 6.67. N-(2-Fluorophenyl)-3-acetylpyrrole (37). IR
(KBr) m (cmꢀ1): 1661 (C@O); 1512 (C@C); 1207
3.23. Preparation of methylketones: general procedure
To a cooled solution (0 ꢁC) of the corresponding hetero-
cyclic aromatic system (5 mmol) in dried CH2Cl2
(30 mL), acetic anhydride (1.4 mL, 7.5 mmol) and BF3.
(CH3CH2)2O (2 mL) were successively added and the
reddish solution obtained was stirred at room tempera-
ture for 6 h. The resulting mixture was poured into ice
(20 mL) and washed with water. The combined extracts
were dried over Na2SO4, filtered off and evaporated un-
der reduced pressure to give the corresponding ketone.

Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
4889
(Ar–O); 1035 (C–O). 1H NMR (CDCl3, 200 MHz) d
3.28. Preparation of the 2-(N-(2-fluorophenyl)pyrrol-3-
yl)thioacetomorpholide (40)
(ppm): 2.47 (s, 3H, CH3); 6.73 (m, 1H, H-5 pyrrole);
7.02 (m, 1H, H-4 pyrrole); 7.25 (m, 4H, H-30, H-40,
H-50, H-60); 7.61 (m, 1H, H-2 pyrrole). 13C NMR
(CDCl3, 50.3 MHz) d (ppm): 27.3 (CH3, CH3–); 110.1
(CH, C-4); 117.4 (CH, J = 20 Hz, C-30); 123.2 (CH,
C-2); 125.2 (CH, C-5); 126.3 (CH, C-50); 127.2 (C,
C-3); 127.3 (C, J = 8 Hz, C-40); 128.7 (CH, J = 8 Hz,
C-60); 130.0 (CH, C-10); 155,2 (C, J = 250 Hz, C-20);
163.5 (C, C@O). Anal. Calcd for C12H10FNO: C,
70.93; H, 4.97; N, 6.89. Found: C. 71.23; H. 4.76; N,
6.59.
Starting from 2-acetyl pyrrole 37 (200 mg, 1.11 mmol)
and following the general procedure the thioamide 40
was obtained as a brown oil (240 mg, 0.79 mmol, 71%
yield). IR (NaCl) m (cmꢀ1): 1467 (C@C); 1253 (Ar–O);
1
1210 (C@S); 1133 (C–O). H NMR (CDCl3, 200 MHz)
d (ppm): 3.55 (t, J = 5.2 Hz, 2H, CHax–N); 3.75 (dd,
J1 = 5.2 Hz, J2 = 4.6 Hz, 4H, CHeq–N, CH2–Ar); 4.23
(s, 2H, CHax–O); 4.35 (t, J = 5.2 Hz, 2H, CHeq–O);
6.28 (t, J = 2 Hz, 1H, H-4 pyrrole); 6.94 (m, 2H, H-2
and H-5 pyrrole); 7.26 (m, 4H, H-30, H-40, H-50, H-60).
MS (EI) m/z (relative intensity): 304 (M+, 8).
3.26. Preparation of arylacetic acids from the corre-
sponding acetyl derivatives. Willgerodt–Kindler reaction
3.29. Biological assay: anti-inflammatory activity
A mixture of the acetyl compound (1 mmol), morphol-
ine (2.5 mmol) and sulfur (S8) (0.25 mmol) was stirred
at 140 ꢁC for 12 h. The reaction mixture was poured
into ice and extracted with CH2Cl2 (3· 30 mL). The
organic phase was dried, filtered off and the solvent
was removed in vacuum to give brown oil which was
purified by silica gel column chromatography using hex-
ane/ethyl acetate as an eluent to afford the correspond-
ing thioamide.
3.29.1. In vitro assay. 3a-HSD activity was determined
by using 5b-dihydrocortisone as substrate and b-nicotin-
amide adenine dinucleotide phosphate reduced form (b-
NADP(H)) as cofactor.
Reduction of 5b-dihydrocortisone was measured
at 25 ꢁC by monitoring the decrease in absorbance of
b-NADP(H) at 340 nM. The reaction mixture contained
2.5 mL of distilled water, 0.3 mL of 1 M potassium
phosphate buffer (pH 6.0), 60 lL of 9 mM NADP(H),
30 lL of 5 mM 5b-dihydrocortisone and 90 lL of com-
pound solution in the tests or DMSO (used to dissolve
compounds) in control experiments. Each assay was ini-
tiated by the addition of 20 lL of crude preparation of
rat liver cytosol20 and the optical density was followed
for 5 min. Enzyme activity was expressed as a variation
in optical density decrease per minute (OD minute) and
the percentage of inhibition of 3a-HSD was calculated
using the following equation:
3.27. Preparation of the 2-(N-(2-fluorophenyl)pyrrole-2-
yl)thioacetomorpholide (38) and 2-(N-(2-fluorophenyl)pyr-
rol-2-yl)-2-oxo-thioacetomorpholide (39)
Following the general procedure described above, start-
ing from 2-acetyl pyrrole derivative 36 (800 mg,
3.94 mmol), morpholine (0.86 mL, 9.85 mmol) and
sulfur S8 (252 mg, 0.95 mmol), the thioamide 38 was
obtained as a brown oil (345 mg, 1.14 mmol, 33% yield)
and the ketothioamide 39 as a brown solid (395 mg,
1.24 mmol, 36% yield). 2-(N-(2-Fluorophenyl) pyrrole-
2-yl)thioacetomorpholide (38). IR (KBr) m (cmꢀ1):
1435 (C@C); 1256 (C@S); 1251 (Ar–O); 1104 (C–O).
1H NMR (CDCl3, 200 MHz) d (ppm): 3.52 (s, 4H,
CH2–, CHax–N); 3.74 (t, J = 5 Hz, 2H, CHeq–N); 4.07
(s, 2H, CHax–O); 4.30 (t, J = 5 Hz, 2H, CHeq–O); 6.16
(m, 1H, H-4 pyrrole); 6.26 (t, J = 4 Hz, H-3 pyrrole);
6.72 (t, J = 4 Hz, H-5 pyrrole); 7.27 (m, 4H, Ar). 13C
% Inhibition ¼ ðOD min control
ꢀ OD min sample=OD min controlÞ
 100
Percent inhibition (mean values of at least four inde-
pendent experiments) of compounds and ibuprofen
at screening concentration of 1000 lM is reported in
Table 1. None of the compounds showed absorbance
at 340 nm at this concentration except for compounds
10–12 that were tested at 500 or 250 lM owing to
their excessive absorbance at 1000 lM. Moreover the
presence at same time of cofactor NADP(H) and sub-
strate 5b-dihydrocortisone was required before the
cytosol promoted a change in absorbance. The con-
centration of compound required to decrease the rate
of 5b-dihydrocortisone reduction by 50% (IC50) was
calculated from the resulting dose–response curve.
NMR (CDCl3, 75.5 MHz)
d (ppm): 42.7 (CH2,
CH2–Ar); 50.0 (CH2, CH2–N); 66.2 (CH2, CH2–O–);
108.2 (CH, C-2 pyrrole); 109.1 (CH, C-4 pyrrole);
116.5 (CH, J = 020 Hz, C-30); 122.8 (CH, C-1 pyrrole);
124.9 (CH, C-4 ); 127.8 (C, C-2 pyrrole); 129.4* (CH,
C-50); 129.9* (C, C-60); 130.2 (C, C-10); 157.2 (C,
J = 250 Hz, C-20); 198.5 (C, C@S). Anal. Calcd for
C16H17FN2OS: C, 63.13; H, 5.63; N, 6.25. Found: C.
63.56; H. 5.98; N, 5.89. 2-(N-(2-Fluorophenyl)pyrrol-2-
yl)-2-oxo-thioacetomorpholide (39), mp: 154–156 ꢁC
(hexane/ethyl acetate). IR (KBr) m (cmꢀ1): 1633 (CO);
1504 (C@C); 1189 (C@S); 1047 (C–O). 1H NMR
(CDCl3, 200 MHz) d (ppm): 3.67 (s, 4H, CH2–N); 3.84
(t, J = 5 Hz, 2H, CH2–Oax); 4.26 (t, J = 5 Hz, 2H,
CH2–Oeq); 6.39 (dd, J1 = 4 Hz, J2 = 2.4 Hz, 1H, H-4
pyrrole); 7.02 (t, J = 2 Hz, 1H, H-5 pyrrole); 7.11 (dd,
J1 = 4 Hz, J2 = 2 Hz, H-3 pyrrole); 7.32 (m, 4H, Ar).
3.29.2. In vivo assay. The carrageenan-induced rat paw
oedema assay was carried out using a modified Winter’s
method as a preliminary screening test.21 The rats (in
groups of six animals weighing 160–200 g, young adult
male Sprague–Dawley) were housed in a controlled
environment and provided with standard rodent chow
and water for 24 h before a dose of the test compounds
*
Interchangeable. MS (EI) m/z (relative intensity): 318
(M+, 73).

4890
Y. Harrak et al. / Bioorg. Med. Chem. 15 (2007) 4876–4890
(70 and 100 mg/kg po) was administered. One hour la-
ter, the volume of the right hind paw was measured,
and 0.05 mL of a 1% suspension of carrageenan in ster-
ile pyrogen-free 0.9% NaCl solution was injected subcu-
taneously into planter aponeurosis of the hind paw.
Three hours after the injection of carrageenan, the
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849–867; (e) Ottana, R.; Maccari, R.; Barreca, M. T.;
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¼ 1 ꢀ Rt=Rc  100ðRt ¼ result of tested group; Rc
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Acknowledgments
We are grateful to the Generalitat de Catalunya (2005-
SGR-000180) and the University of Barcelona (Spain)
for financial support.
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