A series of 1, 2-coupled indane dimers with mast cell stabilisation and smooth muscle relaxation properties

Article abstract of DOI:10.1016/j.ejmech.2009.09.005

Asthma is characterised by bronchoconstriction and inflammation, with infiltration and activation of inflammatory cells such as eosinophils and mast cells, and subsequent release of inflammatory mediators. Much of the therapy directed at the treatment of

Full text of DOI:10.1016/j.ejmech.2009.09.005

European Journal of Medicinal Chemistry 44 (2009) 5018–5022
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
A series of 1, 2-coupled indane dimers with mast cell stabilisation and smooth
muscle relaxation properties
*
**
H. Sheridan , J.J. Walsh, M. Jordan, C. Cogan, N. Frankish
Trinity College Dublin, Department of Pharmacy and Pharmaceutical Sciences, Panoz Institute, Westland Row, Dublin 2, Ireland
a r t i c l e i n f o
a b s t r a c t
Article history:
Asthma is characterised by bronchoconstriction and inflammation, with infiltration and activation of
inflammatory cells such as eosinophils and mast cells, and subsequent release of inflammatory media-
tors. Much of the therapy directed at the treatment of asthma is either to provide symptomatic relief
through bronchodilation or to reduce inflammation to prevent or delay airway remodelling. In an
attempt to address both of these issues, a novel series of 1,2-indane dimers has been synthesized and
evaluated for smooth muscle relaxant and mast cell stabilising activities. We have identified two lead
compounds, 5 and 15, which have substantial mast cell stabilisation activity.
Received 2 December 2008
Received in revised form
2 September 2009
Accepted 3 September 2009
Available online 9 September 2009
Keywords:
Ó 2009 Elsevier Masson SAS. All rights reserved.
Smooth muscle relaxation
Mast cell stabilising activity
Indane dimers
Asthma
1. Introduction
established that a group of synthetic monomeric indanones related
to the pterosin family of natural products exhibit significant smooth
Calcium plays a key role, not only in excitation-contraction
coupling in smooth muscle, but is intimately involved in the release
of mediators from secretory cells such as mast cells. For example,
muscle relaxant activity, by an inhibition of a calcium or calcium/
calmodulin-dependant mechanism [8–12]. More recently we have
observed a similar effect in a number of synthetic dimeric indane
by-products. These compounds also showed significant inhibition
of compound 48/80-stimulated histamine release from rat perito-
neal mast cells [13,14]. We now present data on a series of related
1,2 -coupled indane dimers which are significant inhibitors of
histamine release and have moderate smooth muscle relaxing
activity.
ceramide kinase (CERK) is
a calcium/calmodulin-dependant
enzyme thought to play an important role in mast cell function [1].
Phosphorylation of the sphingolipid metabolite, ceramide by CERK
produces C1P, which has been suggested as an important mediator
of mast cell degranulation [2,3]. Inhibition of CERK can suppress
IgE-mediated mast cell degranulation and small-molecule CERK
inhibitors have been suggested as potential therapeutic agents with
application in the treatment of allergic diseases such as asthma [4].
Furthermore, calcium channel blockers, such as nicardipine, not
only may be expected to have a beneficial effect in asthma as
a consequence of its relaxant effect on bronchial smooth muscle,
but it has also been shown to inhibit the release of Th2-type
cytokines, such as IL4, IL5 and IL13 from T-lymphocytes; such
cytokine release is calcium-dependant and these cytokines are
thought to play an important role in asthma [5].
2. Chemistry
The target compounds in this study were 1, 2-coupled indane
dimers 3–15. We recently prepared compound 2 by base catalysed
condensation during the methylation of bromoindan-1-one [13]. In
this current study we have developed a versatile synthesis for the
2-alkylated, 1, 2-coupled dimeric ketones using compound 1 as
a key intermediate. This compound was prepared in high yield by
the base catalysed condensation of indan-1-one. The lithium eno-
late 2 was readily formed by reaction of 1 with LDA at ꢀ78 ꢁC. The
enolate was then reacted, without isolation, with a range of alkyl
halides (Scheme 1) to yield aliphatic (3, 4, 6, 7 and 12) and aromatic
derivatives (9–11). Compounds 5 and 8 were prepared by Wilkin-
son’s reduction of unsaturated alkyl derivatives 6 and 7 prepared by
direct alkylation of 1. The corresponding alcohols were prepared by
sodium borohydride reduction of a methanolic solution of the
The smooth muscle relaxant and anti-allergenic properties of
simple indanes and indanones has been reported for natural [6] and
synthetic indane compounds [7]. In our earlier studies we have
* Corresponding author. Tel.: þ353 1 8962828x2825.
** Corresponding author.
E-mail addresses: hsheridn@tcd.ie (H. Sheridan), nfrnkish@tcd.ie (N. Frankish).
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.09.005

H. Sheridan et al. / European Journal of Medicinal Chemistry 44 (2009) 5018–5022
5019
t
Scheme 1. a) tBuOK, BuOH, Et2O, rt; b) LDA/THF, ꢀ78 ꢁC; c) R-Hal; d) NaBH4/MeOH.
ketones. The diastereoisomeric alcohols were not separated and the
mixture of isomers was incorporated into the pharmacological
screens. Integration of the CHOH resonances in the 1H NMR spectra
of the diastereoisomeric alcohols established the ratio of the
composite diastereoisomers and where possible the NMR data for
the minor diastereoisomer is reported.
extent than disodium cromoglycate (2 ꢂ 10ꢀ5 M), with 15 being the
most potent, causing an inhibition of histamine release of
49.7 ꢃ 5.3%. In comparison, disodium cromoglycate inhibited
histamine release by 9 ꢃ 0.9% (Table 1). In contrast, compounds 8,
10, 13 and 14 potentiated 48/80-stimulated histamine release, with
values of 27.8 ꢃ 7.7, 26 ꢃ 4.8% and 35.5 ꢃ 6.3% respectively (Table 1).
3. Pharmacology
5. Discussion
3.1. Smooth muscle relaxant activity
We have previously reported that the naturally occurring
monomeric indane, pterosin Z (16) had smooth muscle relaxant
activity against calcium contractions, with an IC50 value of
1.3 ꢂ 10ꢀ6 M. [10]. In comparison, in this study the most potent of
the compounds studied was 14 (IC50 value of 6.2 ꢂ10ꢀ6 M), this
being almost equipotent with 16 and compounds 3–6 which were
approximately equipotent with 14 and 16 at a single dose of
1 ꢂ10ꢀ5 M (Table 1). However, this activity is more than two orders
of magnitude less potent than nifedipine. Such limited smooth
muscle relaxant activity was disappointing and is unlikely to have
any therapeutic potential.
Smooth muscle relaxant activity was assessed on inhibition of
calcium-stimulated (2.5 mM) contractures of isolated guinea-pig
ileum suspended in high-potassium (45 mM), calcium-free Kreb’s
solution, as described previously [9]. The results are shown in Table
1. Compound 13 was evaluated in a dose response study. The IC50
values are shown in Fig. 1.
3.2. Mast cell stabilisation
Mast cell stabilising activity was assessed on inhibition of
histamine release from Compound 48/80-stimulated rat peritoneal
mast cells, as described previously [13]. Peritoneal lavage exudates
were not purified.
Table 1
Effect of compounds 3–15 (1 ꢂ10ꢀ5 M) on inhibition of calcium (2.5 mM) contrac-
tures of guinea-pig ileum suspended in high-potassium (45 mM), calcium-free
4. Results
modified Kreb’s solution and on of Compound 48/80-stimulated (2 mg/ml) histamine
release from rat peritoneal mast cells. Values are expressed as a mean ꢃ SEM,
expressed as a percentage of stimulated values, n as indicated. The effect of nifed-
ipine (1 ꢂ10ꢀ8 M) on inhibition of calcium contractures and of disodium cromo-
glycate (DSCG) (2 ꢂ10ꢀ5 M) on histamine release are shown as a comparison.
Calcium (2.5 mM) caused a sustained contraction of guinea-pig
ileum suspended in high-potassium, calcium-free Kreb’s solution.
Addition of compounds (1 ꢂ10ꢀ5 M) 3–10 and 12–15 caused an
inhibition of the calcium contraction ranging from less than 20% for
compounds 7 and 9 to almost 80% inhibition for 14. Compound 11
was without smooth muscle relaxant activity. In comparison,
nifedipine at 1 ꢂ10ꢀ8 M inhibited contractions by 48% (Table 1). A
subsequent dose response curve to both nifedipine
(1 ꢂ10ꢀ10 ꢀ 1 ꢂ10ꢀ7 M) and compound 14 (3 ꢂ 10ꢀ8 – 1 ꢂ10ꢀ5 M)
demonstrated good concentration-effect relationships and resulted
in calculated IC50 values of 1.47 ꢃ 0.14 ꢂ10ꢀ8 M and
6.2 ꢃ 0.47 ꢂ 10ꢀ6 M respectively (Fig. 1).
Compound Smooth muscle relaxation
Inhibition of histamine release
Mean
SEM
n
Mean
SEM
n
3
4
5
6
7
8
9
10
11
12
13
14
15
41.3
49.6
51.7
51.3
19.9
18.0
18.9
31.5
1.8
20.5
34.3
79.5
25.6
3.8
1.7
3.7
2.0
1.4
2.9
3.2
2.5
4.1
2.7
4.8
2.6
3.1
2.3
8
6
6
6
6
6
7
6
8
6
15.6
19.4
41.2
16.6
32.5
3.2
2.0
3.6
1.7
3.1
12.0
3.2
7.7
2.3
4.4
4.8
6.3
5.3
5
5
5
5
5
5
5
5
5
5
ꢀ3.2
24.7
ꢀ27.8
10.3
21.9
ꢀ26.0
ꢀ35.5
49.7
Incubation of mast cells with disodium cromoglycate or
compounds 3–15 had no effect on basal levels of histamine release,
from rat peritoneal mast cells. With the exception of 8, compounds
were shown to have an effect on compound 48/80-stimulated
histamine release. Compounds 3–7, 9, 11- 12 and 15 (2 ꢂ10ꢀ5 M)
inhibited histamine release to a significantly (p < 0.05) greater
12
6
12
6
10
5
10
Nifedipine 48.1
DSCG
9.1
0.9
20

5020
H. Sheridan et al. / European Journal of Medicinal Chemistry 44 (2009) 5018–5022
7. Experimental protocols
7.1. Chemistry
7.1.1. Synthesis of (Z)-2, 3-dihydro-2-(1, 2-dihydroinden-3-
ylidene)-inden-1-one (1)
Indan-1-one (5 g, 37 mmol) and toluene (80 ml) were placed in
a 250 ml round bottomed flask and the solution was dried by
azeotropic distillation. To this solution was added Aluminium tri-
tert-butoxide (4.7 g, 19 mmol) and the reaction mixture was
refluxed 60 min. Additional Aluminium tri-tert-butoxide (2.3 g,
9.0 mmol) was added after 1 hr. The reaction mixture was cooled
poured onto ice water and the product was extracted into Et2O,
dried and evaporated and the residue was purified by flash column
chromatography (eluent: petroleum ether: Et2O; 9:1). After evap-
oration 1 was recoveþred as a yellow crystalline solid (48%), m.p.
112–114 ꢁC. Found M 246 (C18H14O requires 246.30). ymax (KBr)
Fig. 1. Effect of compound 13 (3 ꢂ 10ꢀ8 ꢀ 3 ꢂ 10ꢀ5 M) and Nifedipine,
(1 ꢂ10ꢀ10 ꢀ 1 ꢂ10ꢀ7 M), (added cumulatively) on inhibition of calcium (2.5 mM)
contractions of guinea-pig ileum suspended in high-potassium (45 mM), calcium-free
modified Kreb’s solution. Values are expressed as a mean ꢃ SEM, n ¼ 6.
2361.2, 1715.1, 1606.9,1459.7 cmꢀ1
. dH (CDCl3, 300 MHz): 3.11 (2H, t,
J ¼ 6 Hz, CH2), 3.54 (2H, m, CH2), 3.98 (2H, s, CH2), 7.53 (6H, m,
6 ꢂ Ar-H), 7.79 (2H, m, 2 ꢂ Ar-H); 1dC (CDCl3, 75.47 MHz): 30.9, 31.5,
33.0, 123.5, 125.7, 125.9,125.9, 126.2, 126.8, 127.2, 130.4, 133.5, 139.5,
140.8, 148.7, 151.7, 154.9, 195.1.
Compounds 5, 7 and 15 were particularly potent as mast cell
stabilisers in comparison with disodium cromoglycate (Table 1).
Compounds 5 and 15 are more than twice as potent (41.2 ꢃ 3.6 and
49.7 ꢃ 5.3 respectively) as 17 (23.0 ꢃ 2.2), the lead 1,2 coupled
dimeric indane identified in our earlier study [13]. Compound 5
most effectively combines smooth muscle relaxant and mast cell
stabilisation activity However, the observation that the smooth
muscle relaxant activity of ketone 5 is increased by more than 50%
on conversion to the corresponding alcohol 14 is not reflected in
mast cell stabilisation activity; indeed the converse is true and we
observed a potentiation of histamine release (Table 1). It would
appear that there is no structure activity relationship in respect of
both smooth muscle relaxant and mast cell stabilisation activities:
there is no correlation between the potencies of the compounds on
inhibition of calcium contractures of guinea-pig ileum and their
activity on inhibition of histamine release (r2 ¼ 0.078, P ¼ 0.33). A
mechanism by which compounds might potentiate compound 48/
80-stimulated histamine release in the absence of any additive
direct effect is not obvious.
7.1.2. General procedures for synthesis of compounds 3–15
7.1.2.1. Lithium diisopropylamide (LDA) alkylation reaction. A dry
three necked (100 ml) round bottomed flask, under nitrogen, was
charged with a solution of dimer in dry THF. The solution was
cooled to ꢀ78 ꢁC and lithium diisopropylamide (LDA) in THF/
heptane/ethylbenzene was added. The solution was stirred at
–78 ꢁC for 10 min and the desired organic halide was added. After
15 min the solution was warmed to room temperature and stirred
for 3 hr. The solution was poured carefully on ice water and
aqueous ammonium chloride (10%) was added. The mixture was
extracted with Et2O (x3). The combined organic extracts were dried
over sodium sulphate and evaporated. The crude product was
purified by flash column chromatography.
7.1.2.2. 2, 3-dihydro-2-(1H-inden-3-yl)-2-methylinden-1-one (3).
Prepared from (1) by a LþDA based alkylation. White solid (80%);
m.p. 112–114 ꢁC. Found M 260 (C19H16 requires 260.32). ymax (KBr)
2361.2, 1715.1, 1606.9, 1459.7 cmꢀ1
. dH (CDCl3, 300 MHz): 1.67 (3H,
s, CH3), 3.20 (1H, d, J ¼ 17 Hz, CH), 3.40 (2H, d, J ¼ 2 Hz, CH2), 3.69
(1H, d, J ¼ 17 Hz, CH), 6.52 (1H, t, J ¼ 2 Hz, CH), 6.87 (1H, d, J ¼ 8 Hz,
Ar-H), 7.15 (2H, m, 2 ꢂ Ar-H), 7.48 (3H, m, 3 ꢂ Ar-H), 7.68 (1H, m, Ar-
H), 7.92 (1H, d, J ¼ 8 Hz, Ar-H). dC (CDCl3, 75.47 MHz): 23.9, 37.6,
41.2, 50.5, 119.8, 124.1, 124.6, 124.8, 125.9, 126.8, 127.7, 130.1, 135.2,
135.6, 143.0, 144.9, 145.8, 152.3. Analysis of C19H16O requires C,
87.69% and H, 6.15%. Found: C, 87.54% and H, 6.25%.
6. Conclusion
The purpose of the study was to determine if it was possible to
synthesise a 1, 2 coupled indane dimer which would combine both
significant smooth muscle relaxant and mast cell stabilising activ-
ities. It was envisioned that the combination of anti-allergic and
bronchodilator activities in the same molecule would yield
a potential new treatment for asthma. The original hypothesis was
that the compounds under investigation interfered in some way
with an element of calcium handling that was shared in both
excitation-contraction coupling and excitation-secretion coupling.
This hypothesis was based on the fact that the calcium/calmodulin
complex and its activation of myosin light chain kinase is a key
factor in both processes [1,15]. However, the lack of correlation
between smooth muscle relaxant and mast cell stabilising activities
and the inverse relationship in compound 14 between the two
types of pharmacological activity suggests that this is not the case.
Despite the inverse relationship in activities observed for
compound 14, the ability of some of the other compounds, partic-
ularly compounds 5 and 15, to inhibit histamine release is signifi-
cant and may have therapeutic application in the areas of allergy
and inflammation.
7.1.2.3. 2, 3-dihydro-2-(1H-inden-3-yl)-2-ethylinden-1-one (4).
Prepared from (1) by a LDA based alkylation. The reaction yield of
(4) was 77%. Found Mþ274 (C20H18O required Mþ274). dH (CDCl3,
300 MHz): 0.83 (3H, t, J 8 Hz, CH3), 2.21 (2H, m, J ¼ 8 Hz, CH2), 3.34
(1H, d, CH), 3.35 (2H,s, CH2), 3.59 (1H, d, J ¼ 17 Hz, CH) 6.49 (1H, t,
J ¼ 2 Hz, CH), 7.15–8.0 (8H, m, 8 ꢂ Ar-H). dC (CDCl3, 75.47 MHz): 8.6,
29.5, 37.4, 38.3, 54.4, 120.1, 123.9, 123.9, 124.4, 125.7, 126.2, 127.3,
129.7, 134.8, 136.9, 143.2, 144.8, 145.1, 152.6, 207.7.
7.1.2.4. 2, 3-dihydro-2-(1H-inden-3-yl)-2-propylinden-1-one (6).
Prepared from (1) by a LDA based alkylation. The reaction yield for
(6) was 67%. Found Mþ286 (C21H18O requires 286.14). dH (CDCl3,
300 MHz): 2.94 (2H, d, CH2CH ¼ CH2), 3.38 (2H, br s, C ¼ CHCH2),
3.53 (2H, ab q, J ¼ 17.5 Hz, CH2), 4.99 (1H, dd, J ¼ 1 Hz, 10 Hz,
CH2CH ¼ CH2), 5.16 (1H, dd, J ¼ 3.3 Hz, 17 Hz, CH2CH ¼ CH2), 5.62
(1H, m, CH2CH ¼ CH2), 6.52 (1H, t, J ¼ 2 Hz, C ¼ CHCH2), 7.06 (1H, m,

H. Sheridan et al. / European Journal of Medicinal Chemistry 44 (2009) 5018–5022
5021
1 ꢂ Ar-H), 7.18 (2H, m, 2 ꢂ Ar-H), 7.46 (3H, m, 3 ꢂ Ar-H), 7.65 (1H, dt,
J ¼ 1.3 Hz & J ¼ 7.6 Hz 1 ꢂ Ar-H), 7.87 (1H, d, J ¼ 7.5 Hz, 1 ꢂ Ar-H). dC
(CDCl3, 75.47 MHz): 37.6, 37.6, 41.1, 53.9, 118.7, 120.2, 124.0, 124.2,
124.6, 125.8, 126.4, 127.6, 130.3, 132.9, 135.2, 136.2, 143.0, 144.8,
144.9, 152.7, 207.4.
2 ꢂ Ar-H). dC (CDCl3, 75.47 MHz): 36.9, 37.9, 41.7, 55.4, 120.5, 124.1,
124.3, 124.8, 126.0, 126.2, 127.4, 129.8, 129.8,, 130.2, 130.3, 130.7,
136.4, 135.2, 135.2, 142.9, 143.1, 144.6, 145.1, 152.3, 171.6, 207.3.
7.1.3. General method for reduction with Wilkinson’s catalyst
Dimers were dissolved in ethanol and ethyl acetate (1:1) and the
resultant solution was stirred at room temperature. To this solution
Wilkinson’s catalyst was added and the reaction was then stirred
under hydrogen for 20 hr. The product was partitioned between
ethyl acetate and water and the organic layer was isolated and
dried with Na2SO4.
7.1.2.5. 2, 3-dihydro-2-(1H-inden-3-yl)-2-((E)-pent-2-enyl)-inden-
1-one (3). Prepared from (1) by a LDA based alkylation as outlined.
The reaction yield for (7) was 40%. Found Mþ316 (C21H18O requires
316.43).dH (CDCl3, 300 MHz): 0.73 (3H, t, CH2CH3), 1.83 (2 H, m,
CH2CH3), 2.85 (2H, d, CH2CH ¼ CH), 3.8 (2H, br s, C ¼ CHCH2), 3.50
(2H, ab q, J ¼ 13.0 Hz, COCCH2), 5.18
&
5.58 (2H, 2 ꢂ m,
CH2CH¼CHCH2), 6.52 (1H, t, J ¼ 2 Hz, 1 ꢂ C ¼ CHCH2), 7.01 (1H, m,
1 ꢂ Ar-H), 7.15 (2H, m, 2 ꢂ Ar-H), 7.40 (3H, m, 3 ꢂ Ar-H), 7.65 (1H, t,
1 ꢂ Ar-H), 7.85 (1H, d, 1 ꢂ Ar-H). dC (CDCl3, 300 MHz): 13.4, 25.4,
37.6, 37.6, 39.9, 54.3, 120.1, 123.1, 124.0, 124.0, 124.6, 125.8, 126.3,
127.4, 130.2, 135.0, 136.6, 136.9, 143.2, 144.9, 145.1, 152.9, 207.9.
7.1.3.1. 2, 3-Dihydro-2-(1H-inden-3-yl)-2-propylinden-1-one (5).
Prepared from 6 using Wilkinson’s catalyst. The crude product was
purified by flash column chromatography to yield (5) 56%. Found
Mþ286 (C21H18O requires 286.36).dH (CDCl3, 300 MHz): 0.88 (3H, t,
J ¼ 7 Hz, CH3), 1.27 (2H, m, CH2), 2.16 (2H, m, CH2), 3.36 (2H, br.s,
C ¼ CHCH2), 3.49 (2H, ab q, J ¼ 17.6 Hz, COCH2) 6.50 (1H, t, J ¼ 2 Hz,
CH), 7.12 (3H, m, 3 ꢂ Ar-H), 7.50 (3H, m, 3 ꢂ Ar-H), 7.64 (1H, dt,
J ¼ 1.2 Hz & J ¼ 7.6 Hz, 1 ꢂ Ar-H), 7.86 (1H, d, J ¼ 7.2 Hz, 1 ꢂ Ar-H). dC
(CDCl3, 75.47 MHz): 14.5 (CH3), 17.6, 37.6, 38.9, 39.2 (4 ꢂ CH2), 54.3
(qC), 120.3 (CH), 124.1, 124.2, 124.6, 125.8, 126.3, 127.6, 129.8, 135.0,
(8 ꢂ Ar-CH), 136.9, 143.3, 144.9, 145.3, 152.8 (4 ꢂ Ar-C & 1 ꢂ C¼C),
208.2 (C¼O).
7.1.2.6. 2-benzyl-2, 3-dihydro-2-(1H-inden-3-yl)-inden-1-one (9).
Prepared from (1) by a LDA based alkylation with benzyl bromide.
The reaction yield for (9) was 73%. Found Mþ336 (C25H20O requires
Mþ 336.15). dH (CDCl3, 300 MHz): 3.37 (2H, dd, C ¼ CHCH2), 3.55
(2H, ab q, J ¼ 13 Hz, CCH2), 3.54 (2H, d, J ¼ 14 Hz, PhCH2), 6.53 (1H, t,
J ¼ 2 Hz, C ¼ CH), 7.12 (5H, m, 5 ꢂ Ar-H), 7.25 (5H, br m, 5 ꢂ Ar-H),
7.47 (2H, m, 2 ꢂ Ar-H), 7.78 (1H, d, J ¼ 7 Hz, 1 ꢂ Ar-H). dC (CDCl3,
75.47 MHz): 36.8, 37.6, 41.7, 55.5, 120.5, 123.9, 124.2, 124.7, 125.9,
126.1, 126.4, 127.7,127.2,130.2, 130.2, 130.4, 134.8, 136.6, 136.7, 143.1,
145.1, 145.1, 152.6.
7.1.3.2. 2, 3-Dihydro-2-(1H-inden-3-yl)-2-pentylinden-1-one (8).
Prepared from 7 using Wilkinson’s catalyst. The crude product was
purified by flash column chromatography to yield (7) 90%. dH
(CDCl3, 300 MHz): 0.88 (3H, t, J ¼ 7 Hz, CH3), 1.27 (2H, m, CH2), 2.16
(2H, m, CH2), 3.36 (2H, br.s, C ¼ CHCH2), 3.49 (2H, ab q, J ¼ 17.6 Hz,
COCH2) 6.50 (1H, t, J ¼ 2 Hz, CH), 7.12 (3H, m, 3 ꢂ Ar-H), 7.50 (3H, m,
3 ꢂ Ar-H), 7.64 (1H, dt, J ¼ 1.2 Hz & J ¼ 7.6 Hz, 1 ꢂ Ar-H), 7.86 (1H, d,
J ¼ 7.2 Hz, 1 ꢂ Ar-H). dC (CDCl3, 75.47 MHz): 14.5 (CH3), 17.6, 37.6,
38.9, 39.2 (4 ꢂ CH2), 54.3 (qC), 120.3 (CH), 124.1, 124.2, 124.6, 125.8,
126.3, 127.6, 129.8, 135.0, (8 ꢂ Ar-CH), 136.9, 143.3, 144.9, 145.3,
152.8 (4 ꢂ Ar-C & 1 ꢂ C¼C), 208.2 (C¼O).
7.1.2.7. Methyl 4-((2, 3-dihydro-2-(1H-inden-3-yl)-1-oxo-1H-inden-
2-yl)-methyl) benzoate (10). Prepared from (1) by an LDA based
alkylation. The reaction yield for 10 was 69%. Found Mþ376
(C26H16O3 requires Mþ 376.40).). ymax (KBr) 1770.9, 1688.2 cmꢀ1 dH
(CDCl3, 300 MHz): 3.37 (2H, dd J ¼ 1.8 Hz, C ¼ CHCH2), 3.45, 3.54
(2H, d, J ¼ 14 Hz, PhCH2), 3.57 (2H, q J ¼ 13 Hz, C–CH2), 3.84 (3H, s,
CH3), 6.48 (1H, t, J ¼ 1.8 Hz, C ¼ CH), 7.25 (7H, m, 7 ꢂ Ar-H), 7.46 (2H,
dt, 2 ꢂ Ar-H), 7.77 (3H, m, 3 ꢂ Ar-H). dC (CDCl3, 75.47 MHz): 36.9,
37.6, 41.6 51.9, 55.4, 128.4, 123.5, 124.0, 124.3, 124.8, 125.9, 126.1,
127.5, 129.2, 130.2, 130.2, 130.6, 135.1, 136.6, 136.7, 142.9, 144.6,
145.1, 152.3, 166.8, 207.2.
7.1.4. Sodium borohydride reduction of dimers
The required dimer was dissolved in ethanol at 0 ꢁC and sodium
borohydride was added to the reaction in small portions over
10 min. The reaction was then allowed to reach room temperature
and stirred for 3 h. The reaction mixture was poured onto water
(20 ml) and extracted into diethyl ether (3 ꢂ 20 ml). Flash column
chromatography over silica gel afforded the product.
7.1.2.8. Methyl 2-(2, 3-dihydro-2-(1H-inden-3-yl)-1-oxo-1H-inden-
2-yl) acetate (12). Prepared from (1) by an LDA based alkylation.
The reaction yield for 12 was 53%. Found Mþ318 (C21H18O3 requires
M
þ 318.36).). ymax (KBr) 1768.5, 1690.5 cmꢀ1 dH (CDCl3, 300 MHz):
3.31 (2H, q J ¼ 16.2 Hz, COCH2), 3.30 (2H, dd, J ¼ 2 Hz, C ¼ CHCH2),
3.54 (3H, s, COOCH3), 3.65 (2H, ab q, CH2COOCH3), 6.31 (1H, t,
J ¼ 1.8 Hz, CH), 7.25 (3H, m, 3 ꢂ Ar-H), 7.42 (3H, m, 3 ꢂ Ar-H), 7.63
(1H, dt, 1 ꢂ Ar-H), 7.91 (1H, m, 1 ꢂ Ar-H). dC (CDCl3, 75.47 MHz):
37.6, 38.2, 39.8, 51.6, 52.0, 120.3, 124.3, 124.8, 125.9, 126.3, 127.5,
130.4, 134.9, 136.1, 142.5, 143.6, 145.0, 152.2, 171.4, 206.2.
7.1.4.1. 2, 3-Dihydro-2-(1H-inden-3-yl)-2-propyl-1H-inden-1-ol (13).
Prepared by sodium borohydride reduction of (5). The reaction yield
of (13) was 90% and was isolated as a mixture of diastereoisomers
(1:2). Where possible the values for the minor diastereoisomer are
presented in italics. dH (CDCl3, 300 MHz): 0.74 (3H, t, J ¼ 7.4 Hz,
CH2CH2CH3),0.84-2.20 (8H, br m, CH3, CH2’s), 3.29 (2H, s,
C ¼ CHCH2), 3.33 (2H, abq, J ¼ 16 Hz, COHCCH2), 3.45 (2H, s, CCH2),
5.37 (1H, s, CHOH), 5.42 (1H, br s, CHOH), 6.28 (1H, t, J ¼ 2.1 Hz,
C ¼ CH), 6.45 (1H,s,C ¼ CH), 7.18–7.81 (8H, m, 8 ꢂ Ar-H). dC (CDCl3,
75.47 MHz): 14.4, 14.8, 18.7 29.7, 34.7, 37.5, 39.4, 40.8, (4 ꢂ CH2), 53.6
(qC), 81.2 (CHOH), 121.7, 124.0, 124.3, 124.4, 124.7, 125.8, 126.7, 128.3,
129.7,130.9, 141.7, 142.6, 144.1, 144.2, 145.3, 146.1, 148.2, (8 ꢂ Ar-CH &
4 ꢂ Ar-C & 1 ꢂ C¼CH & 1 ꢂ C ¼ CH).
7.1.2.9. 2-(2, 3-Dihydro-2-(1H-inden-3-yl)-1-oxo-1H-inden-2-yl)-
acetic acid (11). Benzoate ester (10) (0.1 g, 0.253 m mol) was dis-
solved in a solution of 1.45 M NaOH in 4 ml THF-MeOH-H2O,
(6:3:2). This reaction mixture was refluxed for 20 min. The solution
was cooled and saturated NH4Cl (4 ml), followed by HCl (2 M,
10 mL) was added and the solution was then partitioned with Et2O.
The organic layer was washed and dried to yield 10 which was
purified by column chromatography on SiO2 (n-hexane: EtOAc
gradient) to yield 10 as an oil (69%). Found Mþ362 (C26H16O3
requires Mþ 362.37).). ymax (KBr) 1769.4 cmꢀ1 dH (CDCl3, 300 MHz):
3.39, 3.45 (2H, dd J ¼ 1.8 Hz, C ¼ CHCH2), 3.49, 3.57 (2H, d, J ¼ 14 Hz,
PhCH2), 3.59 (2H, q J ¼ 13 Hz, C-CH2), 6.49 (1H, bs, CH), 7.22 (8H, m,
8 ꢂ Ar-H), 7.47 (2H, t, 2 ꢂ Ar-H), 7.79 (1H, d, 1 ꢂ Ar-H), 7.89(2H, d,
7.1.4.2. 2-Allyl-2, 3-dihydro-2-(1H-inden-3-yl)-1H-inden-1-ol (14).
Prepared by sodium borohydride reduction of (6). The reaction
yield for (14) was 72% and was isolated as a mixture of diastereo-
isomers (1:3). Where possible the values for the minor diastereo-
isomer are presented in italics. dH (CDCl3, 300 MHz): 2.24 (1H, d,
J ¼ 5.39 Hz, CHOH), 2.55 & 2.61 (1H, 2 ꢂ d, CCH2CH ¼ CH2), 2.89 &

5022
H. Sheridan et al. / European Journal of Medicinal Chemistry 44 (2009) 5018–5022
2.94 (1H, 2 ꢂ d J ¼ 6.15 Hz CCH2CH ¼ CH2), 3.33 (2H, g, J ¼ 16 Hz,
CH2), 3.35 (2H, d, J ¼ 2 Hz, C ¼ CHCH2), 4.90 (1H, dd, J ¼ 1 Hz, 10 Hz,
CH2CH ¼ CH2), 4.98 (1H, dd, J ¼ 3.3 Hz, 17 Hz, CH2CH ¼ CH2), 5.49
(H, d, J ¼ 5.37 Hz, CHOH), 5.51 (1H, d, J ¼ 7.9 Hz, CHOH), 5.62 (1H, m,
CH¼CH2), 5.64 (1H, m, C ¼ CHCH2), 6.40 (1H, s, C ¼ CH) 7.19 (5H, m,
5 ꢂ Ar-H), 7.35 (1H, m, 1 ꢂ Ar-H), 7.50 (1H, d, J ¼ 5 Hz, 1 ꢂ Ar-H),
7.72 (1H, d, J ¼ 5 Hz, 1 ꢂ Ar-H). dC (CDCl3, 75.47 MHz): 29.7, 37.4,
37.6, 40.4, 53.0, 81.7, 81.8,116.9,121.7,124.1,124.1,124.4,124.7,125.8,
126.9, 128.4, 129.9, 136.1, 140.7, 143.9, 144.1, 145.3, 148.2.
warmed (37 ꢁC) buffered salt solution (BSS; NaCl 137 mM; KCl
2.7 mM; MgCl2 1.0 mM; CaCl2 0.5 mM; NaH2PO4 0.4 mM; Glucose
5.6 mM; HEPES 10 mM) and centrifuged for 6 min at 1000 rpm,
using a Sigma 204 centrifuge, and the supernatant removed. The
cells were washed 3 times and after the final wash, the pellet
was stored at 4 ꢁC for use as soon as practicable. Cells were
pretreated with disodium cromoglycate or test compound
(2 ꢂ10ꢀ5 M) for 10 min before stimulation of histamine release
with compound 48/80 (2 m
g mlꢀ1). Released histamine was
assayed using O-phthaladehyde.
7.1.4.3. 2,3-Dihydro-2-(1H-inden-3-yl)-2-((E)-pent-2-enyl)-1H-
inden-1-ol (15). Prepared by sodium borohydride reduction of (7).
The reaction yield for (15) was 95% and was isolated as a mixture of
diastereoisomers. dH (CDCl3, 300 MHz): 0.79 (3H, t, J ¼ 7.4 Hz,
CH2CH3), 0.81 (3H, t, J ¼ 7.2 Hz, CH2CH3), 1.83–3.36 (8H, br m, CH2’s),
5.21–5.53 (2H, m, CH2CH¼CHCH2), 5.54 (1H, br s, CHOH), 5.68 (1H,
bs, CHOH), 6.21, 6.43 (1H, 2 ꢂ s, CH¼C), 7.21–7.71 (8H, m, 8 ꢂ Ar-
H).dH (CDC3, 300 MHz): 0.34–3.52 (12H, m, CH2’s), 5.09–5.29 (2H,
m, CH¼CH), 5.36 (1H, br.m, CHOH), 6.42 (1H, d, J ¼ 6.5 Hz, CH¼C),
7.23–7.76 (8H, m, 8 ꢂ Ar-H).
Values are expressed as a mean ꢃ SEM and statistical compari-
sons between groups was performed by one way Anova, followed
by Dunnets Multiple Comparison Test as a post-test. Data were
displayed and statistical analysis was performed using Prism 4
software.
Animals were sacrificed according to guidelines laid down by
the working party report (Laboratory Animals (1996) 30, 293–316,
Laboratory Animals (1997) 31,1–32), on Directive 86/609/EEC (No. L
358, ISSN 0378-6978), which is endorsed by the Bioresources
Ethical Review Committee of the University.
7.2. Pharmacology
References
7.2.1. Smooth muscle relaxation
[1] S. Mitsutake, Y. Igarashi, J. Biol. Chem. 280 (2005) 40436–40441.
[2] S. Mitsutake, T.J. Kim, Y. Inagaki, M. Kato, T. Yamashita, Y. Igarashi, J. Biol.
Chem. 279 (2004) 17570–17577.
[3] T. Baumruker, F. Bornancin, A. Billich, Immunol. Lett. 96 (2005) 175–185.
[4] J.W. Kim, Y. Inagaki, S. Mitsutake, N. Maezawa, S. Katsumura, Y.W. Ryu,
C.S. Park, M. Taniguchi, Y. Igarashi, Biochim. Biophys. Acta. 1738 (2005) 82–90.
[5] B. Gomes, M.D. Cabral, A. Gallard, M. Savignac, P. Paulet, P. Druet, B. Mariame,
M. Moreau, C. Leclerc, J.C. Guery, L. Pelletier, Am. J. Respir. Crit. Care Med. 175
(2007) 1117–1124.
[6] S.T. Ho, M.S. Yang, T.S. Wu, C.H. Wang, Planta. Med. 51 (1985) 148–150.
[7] D.R. Buckle, N.J. Morgan, J.W. Ross, H. Smith, B.A. Spicer, J. Med. Chem. 16
(1973) 1334–1339.
[8] J. Walsh, N. Frankish, H. Sheridan, W. Byrne: New dimeric indane derivatives –
are used as smooth muscle relaxants, mast cell stabilisers and antiinflammatory
agents. For treating asthma or allergies, VENANTIUS LTD (VENA-Non-standard)
2002 874800–A874801.
[9] H. Sheridan, N. Frankish, R. Farrell, Eur. J. Med. Chem. 34 (1999) 953–966.
[10] H. Sheridan, N. Frankish, R. Farrell, Planta. Med. 65 (1999) 271–272.
[11] H. Sheridan, S. Lemon, N. Frankish, P. McArdle, T. Higgins, J.P. James,
P. Bhandari, Eur. J. Med. Chem. 25 (1990) 603–608.
[12] R. Farrell, F. Kelleher, H. Sheridan, J. Nat. Prod. 59 (1996) 446–447.
[13] N. Frankish, R. Farrell, H. Sheridan, J. Pharm, Pharmacology 56 (2004)
1423–1427.
[14] H. Sheridan, J J. Walsh, C. Cogan, M. Jordan, T.McCabe, E. Passante, N.H.
Frankish, Bioorg. Med. Chem. Lett. 19 (2009) 5927–5930.
[15] K.S. Murthy, Annu. Rev. Physiol. 68 (2006) 345–374.
Measurement of smooth muscle relaxant activity was performed
as previously described [11]. In short, guinea pig (250–400 g, either
sex) ileum was removed and 2.5 cm lengths were suspended in
a high potassium calcium-free modified Kreb’s solution (composi-
tion (mM): NaCl 12.5, KCl 45, MgCl2 1.15, NaH2PO4 1.17, NaHCO3 25,
glucose 11.1) at 37 ꢁC, gassed with 95%O2/5%CO2 under a resting
tension of 1.5 g, from Grass FT.03 transducers fitted with black
springs to record contractions isometrically. Contractions were
displayed and assessed using MacLab 4 equipment and Chart 3.4
software. Sustained (>40 min) contractures were elicited by addi-
tion of CaCl2 solution sufficient to raise the calcium concentration in
the bath to 2.5 mM. When contractures had reached a stable
maximum, test compounds were administered at a single concen-
tration of 1 ꢂ10ꢀ5 M or in the case of sufficiently active compounds,
they were added cumulatively (3 ꢂ10ꢀ8 M ꢀ 3 ꢂ10ꢀ5 M).
7.2.2. Mast cell stabilisation
Measurement of mast cell stabilising activity was carried out
as decribed previously [13]. Breifly, peritoneal mast cells were
harvested from female Wistar rats (250–350 g) in 10 ml of pre-