Original 2-alkylamino-6-halogenoquinazolin-4(3H)-ones and KATP channel activity

Article abstract of DOI:10.1021/jm0004648

A series of 6-substituted 2-alkylaminoquinazolin-4(3H)-ones structurally related to 3-alkylamino-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides were synthesized and tested as putative K_ATP channel openers on isolated pancreatic endocrine tissu

Full text of DOI:10.1021/jm0004648

J . Med. Chem. 2001, 44, 2575-2585
2575
Or igin a l 2-Alk yla m in o-6-h a logen oqu in a zolin -4(3H)-on es a n d KATP Ch a n n el
Activity
†
‡,|
‡
†
‡
Fabian Somers, Raogo Ouedraogo, Marie-H e´ l e` ne Antoine, Pascal de Tullio, B e´ n e´ dicte Becker,
|
#
⊥
§
†
‡
J eanine Fontaine, J acques Damas, L e´ on Dupont, Benoit Rigo, J acques Delarge, Philippe Lebrun, and
Bernard Pirotte*
,
†
Laboratoire de Chimie Pharmaceutique, Universit e´ de Li e` ge, 1, Avenue de l’H oˆ pital, B-4000 Li e` ge, Belgium, Laboratoire de
Pharmacodynamie et Th e´ rapeutique, Universit e´ Libre de Bruxelles, 808, route de Lennik, B-1070 Brussels, Belgium,
Laboratoire de Physiologie et Pharmacologie Fondamentales, Universit e´ Libre de Bruxelles, 205/ 7, Campus Plaine,
B-1050 Brussels, Belgium, Laboratoire de Physiologie Humaine, Universit e´ de Li e` ge, 17, Place Delcour, B-4020 Li e` ge, Belgium,
Laboratoire de Cristallographie, Universit e´ de Li e` ge, Sart Tilman, B-4000 Li e` ge, Belgium, and Laboratoire de Synth e` ses
Organiques, Hautes Etudes Industrielles, 13, rue de Toul, F-59046 Lille, France
Received October 31, 2000
A series of 6-substituted 2-alkylaminoquinazolin-4(3H)-ones structurally related to 3-alkyl-
amino-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides were synthesized and tested as putative
K
ATP channel openers on isolated pancreatic endocrine tissue as well as on isolated vascular,
intestinal, and uterine smooth muscle. Most of the 6-halogeno-2-alkylaminoquinazolin-4(3H)-
ones were found to inhibit insulin release from pancreatic B-cells and to exhibit vasorelaxant
properties. In contrast to their pyridothiadiazine dioxide isosteres previously described as more
active on the endocrine than on the smooth muscle tissue, quinazolinones cannot be considered
8
6
45
as tissue selective compounds. Biological investigations, including measurements of Rb, Ca
efflux from pancreatic islet cells and measurements of vasodilator potency in rat aortic rings
exposed to 30 or 80 mM KCl in the presence or the absence of glibenclamide, were carried out
with 6-chloro- and 6-iodo-3-isopropylaminoquinazolin-4(3H)-ones. Such experiments showed
that, depending on the tissue, these new compounds did not always express the pharmacological
profile of pure KATP channel openers. Analyzed by X-ray crystallography, one example of
quinazolinones appeared to adopt a double conformation. This only suggests a partial analogy
between the 2-alkylaminoquinazolin-4(3H)-ones and the 3-alkylamino-4H-pyrido[4,3-e]-1,2,4-
thiadiazine 1,1-dioxides. In conclusion, the newly synthesized quinazolinones interfere with
insulin secretion and smooth muscle contractile activity. Most of the compounds lack tissue
selectivity, and further investigations are required to fully elucidate their mechanism(s) of
action.
In tr od u ction
In the past few years, great interest has been focused
on potassium channels that are sensitive to the intra-
1
cellular levels of adenosine triphosphate (KATP chan-
nels). Those channels open when the intracellular ATP
concentration falls. They have been characterized in
numerous cell types such as cardiac cells, pancreatic
B-cells, skeletal and smooth muscle cells, and central
2
neurons. The role of ATP-sensitive potassium channels
(KATP channels) is well understood in pancreatic B-cells
where they have been shown to control the glucose-
3
,4
induced insulin secretion. In the vascular tissue, KATP
channels are involved in the control of muscle tone and
5
contractility.
F igu r e 1. Chemical structure of pinacidil (1), diazoxide (2),
cromakalim (3), and minoxidil sulfate (4).
Hypoglycaemic sulfonylureas such as glibenclamide
or tolbutamide are generally reported as selective block-
ers of KATP channels.2,3,6 By contrast, compounds such
as pinacidil (1), diazoxide (2), cromakalim (3), or mi-
*
Corresponding author: Bernard Pirotte, Universit e´ de Li e` ge,
Laboratoire de Chimie Pharmaceutique, 1, avenue de l’H oˆ pital, tour
4
3
(+5), B-4000 Li e` ge, Belgium. Phone: +32-4-366-43-65. Fax: +32-4-
noxidil sulfate (4) (Figure 1) are described as potassium
66-43-62. E-mail: B.Pirotte@ulg.ac.be.
†
4,7,8
Laboratoire de Chimie Pharmaceutique, Universit e´ de Li e` ge.
Laboratoire de Pharmacodynamie et Th e´ rapeutique, Universit e´
channel (KATP) openers (PCOs).
PCOs exert mainly
‡
their biological activities by promoting membrane hy-
perpolarization, as a result of their properties to activate
Libre de Bruxelles.
|
Laboratoire de Physiologie et Pharmacologie Fondamentales,
Universit e´ Libre de Bruxelles.
9
the KATP channels. Diazoxide, used in clinical practice
#
Laboratoire de Physiologie Humaine, Universit e´ de Li e` ge.
Laboratoire de Cristallographie, Universit e´ de Li e` ge.
Hautes Etudes Industrielles.
⊥
as an antihypertensive agent, has also an effect on the
insulin releasing process. Its ability to activate vascu-
§
1
0.1021/jm0004648 CCC: $20.00 © 2001 American Chemical Society
Published on Web 07/11/2001

2
576 J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16
Somers et al.
Sch em e 1a
F igu r e 2. Chemical structure of 3-(3′-methyl-2′-butylamino)-
H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxide (5) and 3-(3′,3′-
4
dimethyl-2′-butylamino)-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-
dioxide (6), and general structure of 2-alkylamino-6-halo-
genoquinazolin-4(3H)-ones (13-27). This figure also includes
the general structure of 6,7-dimethoxyquinazolin-4(3H)-ones
a
(
i) SOCl2; (ii) NH4SCN, pyridine, acetone; (iii) CH3I, NaOH,
methanol/water; (iv) RNH2.
(7) and a tertiary carbinol derivative (8).
lar10 as well as pancreatic B-cell11 KATP channels
The 2-alkylaminoquinazolin-4(3H)-ones synthesized
were evaluated on different biological models: pancre-
atic B-cells, rat aorta rings, rat uterus, and guinea pig
ileum. Particular attention was paid to their putative
tissue selectivity. Comparison of the biological activity
between the 6-halogeno-substituted quinazolinones and
a few examples of nonsubstituted derivatives were also
achieved.
indicates a lack of tissue selectivity. In contrast, pina-
cidil and cromakalim exhibit a stronger activity on
smooth muscle cells (relaxation) than on pancreatic
B-cells (inhibition of insulin release).1
1-13
In previous reports, we described 3-alkylamino-4H-
pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides bearing dif-
1
4,15
ferent aminoalkyl side chains in the 3-position.
Those derivatives might be regarded as hybrid com-
pounds between diazoxide and pinacidil. Pharmacologi-
cal investigations have indicated that the target site of
compounds such as 3-(3′-methyl-2′-butylamino)-4H-py-
rido[4,3-e]-1,2,4-thiadiazine 1,1-dioxide (BPDZ 44, 5) or
Ch em istr y
The chemical pathway giving access to the final
products is reported in Scheme 1.
6
-Halogeno-1,2-dihydro-2-thioxoquinazolin-4(3H)-
3
-(3′,3′-dimethyl-2′-butylamino)-4H-pyrido[4,3-e]-1,2,4-
ones 10a and 10b were obtained in a two-step reaction
starting from 5-chloroanthranilic acid (9a ) or 5-iodoan-
thranilic acid (9b). The two carboxylic acids 9a and 9b
were first converted into a more reactive acid chloride
by reaction with thionyl chloride. The latter acid chlo-
ride treated with ammonium isothiocyanate led, after
spontaneous ring closure, to the expected derivatives
thiadiazine 1,1-dioxide (BPDZ 62, 6) was the ATP-
sensitive potassium channel1
6-18
(Figure 2). Whereas
diazoxide did not express tissue selectivity, some of
these original pyridothiadiazine dioxides (i.e., 5) ap-
peared to be more active on the endocrine pancreatic
tissue (inhibition of insulin release) than on the vascular
tissue (smooth muscle relaxation).1
5,19
1
0a and 10b.
Starting from these pyridothiadiazine dioxides, we
decided to investigate original quinazolin-4(3H)-ones
bearing a halogen atom in the 6-position and different
short and branched alkylamino side chains in the
The synthesis of the key intermediates 11 and 12 (6-
halogeno-2-methylsulfanylquinazolin-4(3H)-ones) was
achieved by methylation with methyl iodide of the
corresponding 6-halogeno-1,2-dihydro-2-thioxoquinazo-
lin-4(3H)-ones 10a and 10b in an alkaline hydro-
alcoholic medium. In these experimental conditions,
alkylation only occurred in the 2-position as a result of
the presence of a negative charge located on the exocy-
clic sulfur atom.
6-Chloro- and 6-iodo-2-alkylaminoquinazolin-4(3H)-
ones (13-26) were obtained by the reaction of the
6-halogeno-2-methylsulfanylquinazolin-4(3H)-ones 11
and 12 with an excess of the appropriate alkylamine.
According to the alkylamine boiling point, the reaction
was conducted at reflux or in an autoclave.
2
-position (13-27) (Figure 2). Such compounds are
expected to be analogues of pyridothiadiazine dioxides
since a halogeno-substituted benzene ring is usually
considered as a common isostere of a pyridine ring for
which the nitrogen atom is located in the same position
as the halogeno-substituted carbon atom. Moreover, it
is generally accepted that the carbonyl group can be
used as an isostere of the sulfonyl group. Furthermore,
some 2-alkylaminoquinazolinones (7) have been re-
ported to exhibit a hypotensive activity20 and “ring
closed” tertiary carbinol anilides (8) were claimed as
KATP channel openers21 (Figure 2).

2
-Alkylamino-6-halogenoquinazolin-4(3H)-ones
J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16 2577
Ta ble 1. Effects of 2-Alkylamino-6-halogenoquinazolin-4(3H)-ones on Rat Pancreatic B-Cells: Comparison with Pinacidil, Diazoxide,
and 3-(3′-Methyl-2′-butylamino)-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxide (5)
%
of residual insulin secretion ( SEM (n)a
compd
X
R
50 µM
10 µM
1 µM
eeb
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
I
I
I
I
I
Br
H
H
H
CH(CH3)2
6.6 ( 0.5 (18)
6.0 ( 0.6 (36)
10.2 ( 1.0 (26)
26.5 ( 2.5 (29)
16.5 ( 0.9 (16)
8.9 ( 0.5 (16)
82.5 ( 3.3 (31)
35.0 ( 2.7 (13)
12.9 ( 0.9 (14)
12.2 ( 0.9 (21)
11.2 ( 0.7 (28)
30.6 ( 1.8 (29)
10.0 ( 0.7 (15)
82.8 ( 4.5 (16)
75.7 ( 3.6 (16)
45.6 ( 3.8 (28)
50.9 ( 3.1 (15)
61.8 ( 3.5 (24)
28.8 ( 2.4 (21)
92.1 ( 5.5 (21)
7.1 ( 0.6 (14)
55.1 ( 3.5 (24)
53.2 ( 5.7 (15)
61.9 ( 6.0 (31)
90.1 ( 4.0 (12)
62.1 ( 3.9 (23)
43.6 ( 2.0 (16)
ND
80.7 ( 2.4 (24)
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
CH(CH3)CH2CH3
CH(CH3)CH(CH3)2
CH2C6H11
CH(CH3)C6H11 (R)
CH(CH3)C6H11 (S)
CH2C6H5
CH(CH3)C6H5 (R)
CH(CH3)C6H5 (S)
CH(CH3)2
CH(CH3)CH2CH3
CH(CH3)CH(CH3)2
CH2C6H11
CH2C6H5
CH2C6H5
CH(CH3)2
CH(CH3)CH(CH3)3
CH2C6H5
84.9 ( 4.9 (15)
81.3 ( 3.2 (32)
ND
ND
ND
ND
ND
ND
93.7 ( 4.1 (24)
94.9 ( 2.9 (31)
94.7 ( 5.6 (23)
ND
ND
ND
ND
ND
ND
99.4
97.2
ND
97.4
98.0
76.9 ( 4.9 (16)
90.9 ( 4.5 (24)
77.5 ( 4.8 (30)
87.7 ( 3.7 (31)
65.4 ( 3.9 (14)
ND
ND
ND
ND
ND
c
Diazoxide
Pinacidil
5
70.0 ( 3.6 (22)
96.0 ( 4.2 (20)
26.8 ( 1.8 (21)
78.9 ( 3.8 (21)
97.8 ( 8.8 (13)
70.5 ( 4.4 (19)
d
e
a
b
%
RIS: percentage of residual insulin release from pancreatic islets incubated in the presence of 16.7 mM glucose. ee: enantiomeric
excess; published results. Published results: ref 14. Published results: ref 17. e Published results: refs 14 and 19.
c
d
The synthesis of the 6-bromo-substituted and unsub-
stituted 2-alkylaminoquinazolin-4(3H)-ones (27-30) has
been previously described.22
poor activity on endocrine pancreatic B-cells.11,23 Sub-
stitution of the hydrogen atom in the 6-position by a
chlorine or iodine atom enhanced the inhibitory activity
of the drug on the endocrine tissue (compare 13 and 22
with 28 at 50 µM; P < 0.05). Comparison between the
Resu lts a n d Discu ssion
6
6
-chloro-substituted derivatives (13 to 21) and their
-iodo counterparts (22 to 26) generally showed a weak
The different compounds reported in Table 1 were
tested as inhibitors of insulin release from rat pancreatic
islets incubated in the presence of an insulinotropic
glucose concentration (16.7 mM). Results were ex-
pressed as the percentage of residual insulin secretion.
A 90-95% inhibition (5-10% residual insulin secretion)
may be considered as a full effect relative to the glucose-
insensitive basal insulin release. To define the tissue
selectivity of those new compounds, we have also
investigated their relaxant activity on different smooth
muscles: rat aorta, rat uterus, and guinea pig ileum
difference of activity in favor of the first ones especially
for compounds bearing a short branched hydrocarbon
chain. The three examples of 6-halogeno-substituted
2
-benzylaminoquinazolin-4(3H)-ones (19, 26, 27) were
found to be equipotent and somewhat less active than
the unsubstituted analogue (30) (19, 26, 27 vs 30 at 50
µM; P < 0.05). At the lower concentration tested (10
µM), the 6-chloro-substituted compounds 13, 14, and 18
were the most potent quinazolinones.
1
4
Some optically active 6-chloro-substituted quinazoli-
nones were prepared by introducing an alkylamino side
chain in the 2-position bearing an asymmetric carbon
atom. At a 50 µM concentration, the S-enantiomers 18
and 21 were found to be more potent than their
R-counterparts 17 and 20, respectively (P < 0.05). This
finding was corroborated by experiments performed at
a 10 µM concentration for 17 and 18 (P < 0.05).
(
Table 2). The effect of the compounds were compared
with those of three reference molecules: pinacidil (a
pyridyl-alkylcyanoguanidine), diazoxide (a benzothia-
diazine dioxide), and 5 (a 3-(3′-methyl-2′-butylamino)-
substituted pyridothiadiazine dioxide).
Effect on P a n cr ea tic B-Cells. As observed in Table
, except for the benzylamino-substituted compounds
9, 26, and 27, most of the 2-alkylamino-6-halogeno-
1
1
quinazolin-4(3H)-ones were found to markedly inhibit
the insulin releasing process at a 50 µM drug concen-
tration. Some of them (13-15, 17, 18, 21, 23, 25), at a
Whatever the nature of the halogen atom in the
6-position (Cl: 13, 14, 15 or I: 22, 23, 24), the enhance-
ment of the size and the branching of the aliphatic side
chain did not markedly modify the effects of the drugs
on the insulin releasing process. These findings contrast
with previous results showing that, for 3-alkylamino-
4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides, the best
chain eliciting a potent biological activity was the 3-(3′-
methyl-2′-butylamino) side chain (as that found in
1
0 µM concentration, were more potent than diazoxide
(13, 14, 18 vs diazoxide; P < 0.05) or at least equally
potent as the reference drug (15, 17, 21, 23, 25 vs
diazoxide; P > 0.05). None of those derivatives, at this
concentration, were found to be of comparable potency
than 5, the most potent drug on this model (18 vs 5; P
1
4,15
<
0.05). As previously described, pinacidil exhibited a
5
).

2
578 J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16
Somers et al.
Ta ble 2. Myorelaxant Activity of 6-Halogeno-2-alkylaminoquinazolin-4(3H)-ones on Rat Aorta, Rat Uterus, and Guinea Pig Ileum:
Comparison with Pinacidil, Diazoxide, and 3-(3′-Methyl-2′-butylamino)-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxide (5)
myorelaxant activity on smooth muscles
rat uterus
%
residual contractile activity ( SEM (n)b
rat aorta
guinea pig ileum
IC50 ( SEM (n)
compd
X
R
IC50 ( SEM (n)a
50 µM
10 µM
c
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
I
I
I
I
I
Br
H
H
H
CH(CH3)2
17.3 ( 5.9 (6)
13.8 ( 3.4 (6)
16.3 ( 4.2 (4)
2.2 ( 1.1 (4)
5.6 ( 1.3 (12)
2.1 ( 0.3 (4)
3.2 ( 0.4 (7)
2.8 ( 0.6 (4)
1.7 ( 0.1 (4)
12.1 ( 2.3 (12)
8.9 ( 3.3 (8)
4.1 ( 0.8 (6)
3.9 ( 1.2 (4)
1.4 ( 0.3 (4)
7.6 ( 1.3 (5)
67.3 ( 11.4 (4)
12.4 ( 2.0 (4)
43.7 ( 6.5 (6)
19.3 ( 1.5 (21)
0.5 ( 0.1 (28)
154 ( 15 (8)
61.0 ( 4.4 (4)
ND
ND
78.7 ( 7.0 (4)
ND
ND
74.1 ( 6.5 (3)
44.7 ( 7.3 (8)
59.2 ( 2.6 (4)
23.9 ( 3.7 (6)
8.2 ( 0.7 (5)
15.1 ( 1.7 (4)
13.3 ( 2.8 (4)
20.2 ( 2.5 (5)
13.2 ( 1.8 (5)
44.1 ( 5.4 (4)
23.6 ( 10.3 (3)
30.4 ( 4.5 (8)
26.0 ( 4.0 (4)
8.7 ( 1.7 (4)
ND
ND
ND
ND
>300 (7)
9.2 ( 2.2 (18)
>300 (6)
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
CH(CH3)CH2CH3
CH(CH3)CH(CH3)2
CH2C6H11
CH(CH3)C6H11 (R)
CH(CH3)C6H11 (S)
CH2C6H5
CH(CH3)C6H5 (R)
CH(CH3)C6H5 (S)
CH(CH3)2
CH(CH3)CH2CH3
CH(CH3)CH(CH3)2
CH2C6H11
CH2C6H5
CH2C6H5
CH(CH3)2
CH(CH3)CH(CH3)3
CH2C6H5
80.3 ( 0.5 (4)
90.7 ( 2.6 (4)
66.5 ( 8.4 (4)
98.1 ( 5.2 (4)
46.5 ( 6.5 (4)
44.9 ( 6.8 (8)
41.0 ( 2.3 (8)
ND
86.0 ( 2.2 (4)
108 ( 2 (4)
102 ( 2 (4)
94.8 ( 9.4 (4)
120 ( 7 (4)
92.4 ( 8.3 (8)
77.6 ( 4.2 (8)
ND
ND
ND
97.9 ( 7.8 (4)
106 ( 5 (8)
76.6 ( 5.3 (4)
ND
96.8 ( 7.4 (4)
106 ( 5 (8)
76.8 ( 4.1 (4)
ND
ND
ND
47.4 ( 3.4 (4)
76.3 ( 4.9 (4)
35.5 ( 2.9 (4)
ND
97.2 ( 6.2 (4)
93.8 ( 2.2 (4)
58.1 ( 4.4 (4)
ND
d
Diazoxide
Pinacidil
5
d
d
a
IC50: drug concentration (µM) giving 50% relaxation of the 30 mM KCl-induced contraction of rat aorta rings. b Percentage of contraction
(
residual) of the rat uterine smooth muscle induced by 20 mU oxytocin in the presence of 10 and 50 µM of drugs. Contraction in the
c
absence of drugs is referenced to 100%. IC50: drug concentration (µM) giving 50% relaxation of the electrically stimulated guinea pig
d
ileum segments. Published results: ref 29.
Effect on Sm ooth Mu scle Cells. PCOs such as
pinacidil, cromakalim, or diazoxide have been reported
to exert myorelaxant activities on a variety of smooth
muscles such as the vascular, the ileal, and the uterine
smooth muscle.24 To characterize the similarities be-
tween the newly synthesized quinazolinones and known
PCOs, their activity on these three different tissues were
investigated and compared with three reference drugs:
diazoxide, pinacidil, and 3-(3′-methyl-2′-butylamino)-4H-
pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxide (5) (Table 2).
Effect on Ra t Aor ta . Pharmacological data clearly
indicated that the 6-chloro-, 6-bromo-, and 6-iodo-2-
alkylaminoquinazolin-4(3H)-ones (13-27) as well as the
unsubstituted derivatives (28-30) were active on the
vascular tissue and inhibited the KCl (30 mM)-induced
contraction (Table 2). According to their potency, the
drugs could be divided in three groups. The first group
was a series of compounds (16-21, 23-27) with marked
vasorelaxing properties and exhibiting IC50 values below
22, 23). According to the results obtained with the
2-benzylamino-substituted (19, 26, 27, 30) and the
2-isopropylamino-substituted quinazolinones (13, 22,
28), it clearly appeared that the introduction of a
halogen atom in the 6-position increased the myorelax-
ant activity of the drugs (13 and 22 > 28, P < 0.05; 19,
26 and 27 > 30, P < 0.05). In the 6-chloro-substituted
group (13-21), the enhancement of the size and the
branching of the alkylamino side chain did not induce
any important modification of the vasorelaxant activity.
However, when substitution was made with iodine, the
increasing branching of the chain appeared suitable for
a higher myorelaxant activity (24 > 23 > 22). Compari-
son between compounds of the R-geometry (17 and 20)
and their S-counterparts (18 and 21) indicated that the
absolute configuration of the first carbon atom of the
lateral chain seemed to be of minor importance for
activity on the vascular tissue. An interesting observa-
tion was given by the finding that some of the most
potent 2-alkylaminoquinazolin-4(3H)-ones (i.e., the ben-
zylamino-substituted compounds 19, 26, 27) were poorly
active as inhibitors of the insulin releasing process. This
could foreshadow a potential tissue selectivity for the
vascular smooth muscle versus the pancreatic tissue.
Effect on Gu in ea P ig Ileu m . The second model
developed for the biological testing of these quinazoli-
nones was the electrically stimulated guinea pig ileum
(coaxial stimulation). Potassium channel openers such
as pinacidil have been found to exert a myorelaxant
1
0 µM. These compounds were much more potent than
diazoxide but less potent than pinacidil. The second
group consisted of compounds 13-15, 22, and 29 of
intermediate activity but still more potent or equipotent
to diazoxide. Finally, quinazolinones 28 and 30 were at
least 2 to 3 times less potent than diazoxide.
In the 6-chloro- and 6-iodo-substituted series, com-
pounds bearing a cycloalkylalkylamino- (16-18, 25) or
a arylalkylamino- (19-21, 26) moiety in the 2-position
were found of higher potency than most of the short
branched 2-alkylamino-substituted derivatives (13-15,
2
5,26
activity on the gastrointestinal tract.
Since glib-

2
-Alkylamino-6-halogenoquinazolin-4(3H)-ones
J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16 2579
enclamide antagonized these relaxant effects of pinaci-
8
,24-26
dil, the presence of KATP channels was suggested.
Our data revealed that most of the quinazolinones
induced intestinal smooth muscle relaxation (Table 2).
Among those, 17 and 26 (IC50 ) 8.2 µM and 8.7 µM)
exhibited a myorelaxant activity which was of the same
order of magnitude than that expressed by pinacidil
(IC50 ) 9.2 µM). With IC50 values above 300 µM, 5 and
diazoxide can be considered as inactive compounds.
Comparison between the 6-chloro-substituted quinazoli-
nones and their 6-iodo-substituted counterparts did not
provide a clear and obvious difference in potency.
However, the substitution of the chlorine atom in the
6
-position by an iodine atom could, in some cases,
slightly improve their myorelaxant activity on the
gastrointestinal smooth muscle (compare 13 and 22, P
<
0.05; 14 and 23, P > 0.05; 15 and 24, P < 0.05).
Likewise, the influence of the nature of the chiral carbon
atom located on the hydrocarbon side chain was not
clearly defined. Regarding the (R)- and (S)-1-cyclohexyl-
ethylamino-substituted molecules (17 and 18), the R
absolute geometry seemed to be responsible for an
improvement of the myorelaxant properties (IC50 17 )
8
.2 µM, IC50 18 ) 15.1 µM; 17 vs 18, P < 0.05). Such an
influence of stereochemistry was not confirmed with the
R)- and (S)-1-phenylethylamino-substituted derivatives
0 and 21. Compounds 19 and 26 (2-benzylamino-
(
2
quinazolin-4(3H)-ones) were again identified as potent
myorelaxant drugs (aorta and ileum), being poorly
active on the endocrine pancreatic tissue.
Effect on Rat Uter u s. The newly synthesized 2-alkyl-
amino-quinazolin-4(3H)-ones were evaluated on rat
uterus as inhibitors of the contractile activity induced
by oxytocin (Table 2). Pinacidil, the most potent com-
pound, induced a dose-dependent myorelaxant activity.
At a 10 µM concentration, the quinazolinones were
found to be poorly active. At the higher concentration
F igu r e 3. Upper panel: Effect of 15 (50 µM) on 86Rb outflow
from rat pancreatic islets perifused throughout in the absence
(
O) or presence (b) of glibenclamide (10 µM). Basal media
contained 5.6 mM glucose. Mean values ((SEM) refer to 4-9
individual experiments. Lower panel: Effect of a rise in the
+
45
extracellular concentration of K from 5 to 50 mM on Ca
outflow from rat pancreatic islets perifused throughout in the
absence (0) or presence (9) of 15 (50 µM). Basal media
contained 2.8 mM glucose. Mean values ((SEM) refer to six
individual experiments.
(50 µM), biological effects remained moderate, except
for compounds 20-22 and 30.
Taken as a whole, the pharmacological results indi-
cate that the 2-alkylamino-quinazolin-4(3H)-ones were,
in most cases, active on pancreatic B-cells as well as on
smooth muscle cells. However, and according to the
compound, the biological responses did not occur in the
same range of concentration.
out, the stimulatory effect of compound 15 (50 µM) was
totally abolished (Figure 3, upper panel). Experiments
conducted with compound 13 also revealed a stimula-
tory effect on Rb outflow from perifused rat pancreatic
islets (data not shown).
86
Two main mechanisms might be responsible for the
inhibition of insulin release and for the myorelaxant
activity. Indeed, such biological effects could result from
However, both compounds 15 and 13 were less potent
86
than the reference compound 5 at enhancing Rb
16
outflow from prelabeled pancreatic islets.
+
the opening of ATP-sensitive K channels or from the
To further investigate the mechanism of action of
direct blocking of voltage-dependent Ca2 channels. To
detect the mechanism of action of the new drugs,
additional pharmacological investigations were carried
out on rat pancreatic islets and rat aorta.
+
45
compound 15, we characterized its effect on the Ca
+
outflow response to high extracellular K concentration.
27
As previously reported, a sudden rise in the extracel-
+
lular concentration of K (from 5 to 50 mM) induced an
Mea su r em en ts Of 86Rb a n d 45Ca Ou tflow fr om
P er ifu sed Ra t P a n cr ea tic Islets. Figure 3 illustrates
the effect of compound 15, the isosteric analogue of the
immediate and marked increase in Ca outflow from
45
prelabeled and perifused rat pancreatic islets (Figure
3, lower panel). Compound 15 (50 µM), when present
in the basal medium, did not affect the cationic response
pyridothiadiazine dioxide 5,1 on Rb outflow ( K
substitute) from prelabeled and perifused rat pancreatic
islets. In the presence of 5.6 mM glucose in the basal
medium, the addition of 15 (50 µM) provoked a rapid,
6
86
42
+
to high K (Figure 3, lower panel). Indeed, the inte-
4
5
grated outflow of Ca observed during exposure to 50
+
mM K and corrected for basal value averaged 1.09 (
8
6
sustained, and rapidly reversible increase in
Rb
0.10%/min in the absence and 0.99 ( 0.08%/min in the
presence of compound 15 throughout (P > 0.05).
These radioisotopic experiments conducted on prela-
beled and perifused rat pancreatic islets suggest that
outflow rate (Figure 3, upper panel). When the same
experiment was repeated in the presence of the hypo-
glycaemic sulfonylurea glibenclamide (10 µM) through-

2
580 J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16
Somers et al.
Ta ble 3. Effects of Selected 6-Halogeno-2-alkylaminoquinazolin-4(3H)-ones on the Contractile Activity of 30 mM and 80 mM
K+-Depolarized Rat Aorta Incubated in the Absence or the Presence of 1 and 10 µM Glibenclamide: Comparison with Pinacidil and
Diazoxide
myorelaxant activity on rat aorta
IC50 30 mM KCl ( SEM (n)a
compd
X
R
1 µM glib.
10 µM glib.
IC50 80 mM KCl ( SEM (n)b
1
1
2
3
7
2
Cl
Cl
I
CH(CH3)2
CH(CH3)C6H11 (R)
CH(CH3)2
17.3 ( 5.9 (6)
7.6 ( 1.5 (8)
12.1 ( 2.3 (12)
19.3 ( 1.5 (21)
0.5 ( 0.1 (28)
ND
ND
34.3 ( 5.1 (8)
18.1 ( 4.4 (6)
37.2 ( 3.8 (7)
>300 (6)
>30 (7)c
>30 (5)c
37.3 ( 7.4 (6)
85.8 ( 22.2 (6)
10.4 ( 1.1 (8)
46.4 ( 7.4 (6)
163 ( 41 (6)
42.5 ( 2.8 (8)
d
Diazoxide
Pinacidil
d
16.0 ( 1.4 (8)
a
IC50: drug concentration (µM) giving 50% relaxation of the 30 mM KCl-induced contraction of rat aorta rings incubated in the absence
b
of glibenclamide, in the presence of 1 µM glibenclamide (glib.), and in the presence of 10 µM glibenclamide. IC50: drug concentration
d
(
µM) giving 50% relaxation of the 80 mM KCl-induced contraction of rat aorta rings. c The compound precipitates at 100 µM. Published
results: ref 29.
the primary effect of compound 15 is to activate the KATP
channels equipping the pancreatic B-cell plasma mem-
brane. Indeed, the drug accelerated 86Rb outflow from
prelabeled rat pancreatic islets, an effect which can be
interpreted as the result of an increase in the membrane
+
4
86
K
permeability. Moreover, this rise in Rb outflow
was completely abolished by glibenclamide, a hypogly-
caemic sulfonylurea reported to close the KATP chan-
2
,3,6
nels.
Last, the lack of effect of compound 15 on the
increment in 45Ca outflow evoked by high K indicates
+
that the drug does not directly interact at the level of
voltage-sensitive Ca2 channels.
+
27
F igu r e 4. Possible tautomeric forms of the 6-substituted
-alkylaminoquinazolin-4-ones.
Eigh ty Millim ola r KCl-In d u ced Con tr a ction s
a n d In flu en ce of Gliben cla m id e on th e Con tr a ctile
Resp on ses of Ra t Aor ta . To further evaluate the
possible PCOs properties of these new quinazolinones,
2
the glibenclamide concentration in the bathing medium.
When calculating the ED50 ratio for experiments con-
ducted in the absence and the presence of 10 µM
glibenclamide, we found that the hypoglycaemic sulfo-
nylurea displaced the concentration-response curve 3.8-
fold for 22, 8.4-fold for diazoxide, and 212.5-fold for
pinacidil. For compound 17, the myorelaxant activity
was also found to be less pronounced in the presence of
glibenclamide. Unfortunately, the IC50 values could not
be calculated due to the poor solubility of the drug in
physiological medium over 30 µM.
+
vasorelaxant activities on K -depolarized rat aorta have
been measured in different experimental conditions.
Three drugs, the 6-chloro- and 6-iodo-2-isopropylamino-
quinazolin-4(3H)-ones (13, 22) and 6-chloro-2-[R-(1-
cyclohexyl)ethylamino]quinazolin-4(3H)-one (17), have
been selected. First, the myorelaxant potency of 13, 17,
and 22 was examined versus diazoxide and pinacidil on
rat aorta rings precontracted with a 80 mM KCl
solution. Under such experimental conditions, the vaso-
dilator efficiency of pure K+ channel openers must
theoretically be suppressed or at least significantly
reduced. Conversely, drugs interfering directly at the
All together, and compared to the reference molecules,
such observations do not support the view that these
quinazolinones act as pure potassium channel openers.
Other mechanism(s) of action, including a direct inter-
2
+
level of Ca channels, such as calcium entry blockers,
are expected to exhibit identical myorelaxant activity
2
8
2+
on 30 and 80 mM KCl-precontracted aorta rings.
ference at the level of voltage-sensitive Ca channels,
As reported in Table 3, the myorelaxant activities of
3, 17, and 22 were 2 to 3 times less pronounced when
could mediate the vasorelaxant properties of such
compounds.
1
a 80 mM KCl solution was used for eliciting aorta ring
contraction (30 vs 80 mM KCl; p < 0.05). By contrast,
the myorelaxant activity of pinacidil and diazoxide was
more markedly reduced under these experimental con-
ditions.
Cr ysta llogr a p h y. According to the possible delocal-
ization of the CdN double bond in the heterocyclic ring
system and independently of the orientation of the
hydrocarbon side chain, the 2-alkylaminoquinazolinones
could theoretically exist in four different tautomeric
forms: the 1H-, the 3H-, the 1H,3H-, and the aromatic
form (Figure 4). The knowledge of the conformational
aspects associated to this kind of ring system could help
the identification of the most probable conformation
adopted by the bioactive molecule in solution or during
its interaction with its binding site. Assuming that
Compounds 17 and 22 were also tested on 30 mM K+-
depolarized rat aorta rings incubated in the absence and
in the presence of 1 or 10 µM glibenclamide, a blocker
of KATP channels2
,3,6,13
(Table 3). For the two reference
molecules as for 22, a dose-dependent decrease of the
myorelaxant efficiency was observed when increasing

2
-Alkylamino-6-halogenoquinazolin-4(3H)-ones
J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16 2581
F igu r e 6. Four possible orientations of the hydrocarbon side
chain of the 1H- and 3H-tautomeric forms of 6-chloro-2-
isopropylaminoquinazolin-4-one: conformation 1H (I) and 3H
(II) are found in the solid state. The figure also includes
(bottom) the conformation of 3-isopropylamino-4H-pyrido[4,3-
e]-1,2,4-thiadiazine 1,1-dioxide (31) in the solid state.
F igu r e 5. Molecular structure of 13 (molecule A/conformer
II and molecule B/conformer I) with atom-labeling scheme.
Thermal ellipsoids are shown at 50% probability levels. H
atoms are drawn as small circles of arbitrary units.
The elemental analysis of 13 suggested the presence
of a half water molecule of crystallization. This observa-
tion was corroborated by X-ray crystallography (Figure
5
).
crystallographic data on 2-alkylaminoquinazolinones
can provide information to determine the most probable
tautomer, we tried to establish the X-ray structure of
Although compound 13 does not present, in the solid
state, the same side chain orientation as its pyrido-
thiadiazine dioxide counterpart 31, it cannot be ex-
cluded that, in solution, the drug adopts, at least in part,
the 1H(III)-conformation (see Figure 6). Such a confor-
mation could explain the pharmacological profile of 13
as a PCO structurally related to diazoxide and pyrido-
thiadiazine dioxides.
6
-chloro-2-isopropylaminoquinazolin-4(3H)-one (13). The
X-ray data of 13 were collected and compared to those
of diazoxide30 and 3-isopropylamino-4H-pyrido[4,3-e]-
1
,2,4-thiadiazine 1,1-dioxide (31).15
It was previously reported that, in the solid state,
diazoxide and 31 adopted the same 4H-tautomeric
form.15 For both drugs, the N(2)-C(3) length was
shorter than the N(4)-C(3) length, supporting the view
that the CdN double bond of the thiadiazine ring was
located in the 2,3-positions (numbering, see Figure 6).
By contrast, X-ray analysis of 13 demonstrated that the
drug was present, in the crystal, in two different
tautomeric forms (Figure 5). Each asymmetric unit
contains one conformer (I) where N(3)-C(2) (1.336 Å)
is shorter than N(1)-C(2) (1.351 Å) (1H-tautomer), and
a second conformer (II) where the N(3)-C(2) (1.381 Å)
is longer than the N(1)-C(2) length (1.322 Å) (3H-
tautomer) (numbering, see Figure 6). It must be em-
phasized that the H(N) hydrogen positions were located
by Fourier-difference synthesis, and included in the
refinement. The scheme of hydrogen bonds in the
structure confirms the existence of the 1H- and the 3H-
tautomers in the asymmetric unit. Moreover, the spatial
orientation taken by the alkylamino side chain in each
tautomer of 13 was different from that found in 31. In
the latter case, the two N-H hydrogen atoms located
on the exocyclic and on the N(4) nitrogen atoms adopted
a spatial orientation quite similar to that of the H atoms
of the two cyanoguanidinic N-H groups of pinacidil in
Con clu sion s
6
-Halogeno-substituted 2-alkylaminoquinazolin-4(3H)-
ones expected to be structural analogues of 3-alkyl-
amino-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides were
synthesized and tested on distinct pharmacological
models. Except the 2-benzylamino-substituted deriva-
tives 19 and 26, most of the new compounds were found
to express a marked inhibitory activity on insulin
release. On pancreatic B-cells, the 6-chloro-substituted
molecules were generally more potent than the other
compounds and, in this series, the S-enantiomers were
found to be slightly more active than their R-counter-
parts. When investigated on three different smooth
muscle preparations, most of the quinazolinones also
showed myorelaxant activities.
Taken as a whole, these results suggest that most
quinazolinones synthesized in the present study are not
tissue selective in contradistinction to their pyridothia-
diazine dioxides isosteres. Such isosteres were previ-
ously described as being more active on insulin secreting
1
5
cells than on smooth muscle cells.
Experiments conducted to characterize the mecha-
nism of action of selected quinazolinones revealed that,
3
1
the solid state (Figure 6).

2
582 J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16
Somers et al.
1
on pancreatic B-cells, compound 15 behaved as a KATP
O), 1605, 1581, 1465 (CdN, CdC, N-H). H NMR (DMSO-d
δ: 2.45 (s, 3H, SCH ), 7.45 (d, 1H, 8-H), 7.70 (dd, 1H, 7-H),
7.85 (d, 1H, 5-H). Anal. (C ClN OS): C, H, N, S.
-Iod o-2-m eth ylsu lfa n ylqu in a zolin -4(3H)-on e (12). The
6
)
channel opener. This compound, however, was less
3
1
6
9
H
7
2
potent than its pyridothiadiazine isostere (5 ) to acti-
vate KATP channels and to inhibit insulin release. By
contrast, the pharmacological profile of quinazolinones
suggest that their vasorelaxant properties result from
a more complex mechanism of action.
6
title compound was obtained from 6-iodo-1,2-dihydro-2-thioxo-
quinazolin-4(3H)-one (10b) (7 g, 0.023 mol) by following the
same experimental conditions as described for 6-chloro-2-
methylsulfanylquinazolin-4(3H)-one (11) (yield 4.61 g, 63%).
Last, X-ray crystallography analysis indicated that
quinazolinone (13) appeared to adopt, in the solid state,
a double conformation. The crystallographic data only
suggested a partial analogy between the 3-alkylamino-
Mp: 253-255 °C. IR (KBr): 3149 (N-H), 1677 (CdO), 1580,
1
1
547, 1457 (CdN, CdC, N-H). H NMR (DMSO-d
6
) δ: 2.45
(
5
s, 3H, SCH
3
), 7.25 (d, 1H, 8-H), 7.90 (d, 1H, 7-H), 8.15 (s, 1H,
-H), 12.40 (bs, 1H, NH). Anal. (C IN OS): C, H, N, S.
-Ch lor o-2-isopr opylam in oqu in azolin -4(3H)-on e Hem i-
9
H
7
2
6
4
2
H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides and the
-alkylaminoquinazolin-4(3H)-ones.
h yd r a te (13). A solution of 6-chloro-2-methylsulfanylquinazo-
lin-4(3H)-one (11) (0.5 g, 2.2 mmol) in isopropylamine (7 mL)
was heated in an autoclave at 150 °C for 5 h. The excess of
amine was removed under reduced pressure and the residue
was suspended in water (20 mL). The insoluble material was
dissolved by addition of a 10% w/v aqueous solution of NaOH.
After treatment with activated charcoal and filtration, the
filtrate was adjusted to pH 5 with formic acid. The title
compound was collected by filtration, washed with water, and
dried (yield 0.36 g, 67%). Mp: 227-229 °C. IR (KBr): 3240
In conclusion, the newly synthesized quinazolinones
inhibit the glucose-induced insulin release and depress
the contractile activity of vascular and gastrointestinal
smooth muscle. However, and compared to their pyrido-
thiadiazine dioxides isosteres, these compounds lack
tissue selectivity. Further investigation is required to
fully elucidate the mechanism(s) of action of this new
family of compounds.
1
(N-H), 1671 (CdO), 1623, 1596, 1475 (CdN, CdC, N-H). H
NMR (DMSO-d
3 2 3 2
CH(CH ) ), 6.20 (m, 1H, NHCH(CH )
6
) δ: 1.10 (d, 6H, CH(CH
3
)
2
), 4.00 (m, 1H,
), 7.20 (d, 1H, 8-H), 7.50
dd, 1H, 7-H), 7.70 (d, 1H, 5-H), 10.80 (bs, 1H, NH). Anal.
Exp er im en ta l Section
(
(
Ch em istr y. The reactions were monitored by TLC using
precoated aluminum-backed plates (Kieselgel HF254 type 60,
Merck). Melting points are uncorrected and were determined
on a B u¨ chi-Tottoli capillary apparatus. IR spectra were
recorded as KBr pellets on a Perkin-Elmer 1750 FT-spectro-
1
C
11
H
12ClN
3
O‚ /
2 2
H O): C, H, N.
6
-Ch lor o-2-R,S-(2-b u t yla m in o)q u in a zolin -4(3H )-on e
Mon oh yd r a te (14). The title compound was obtained as
described for 13 starting from 6-chloro-2-methylsulfanylquinazo-
lin-4(3H)-one (11) (0.5 g, 2.2 mmol) and 2-butylamine (10 mL)
1
photometer using Spectrum for Windows version 1.5. The H
(
1
(
(
yield 0.33 g, 55%). Mp: 200-202 °C. IR (KBr): 3238 (N-H),
NMR spectra were taken on a Brucker AW-80 (80 MHz) in
1
672 (CdO), 1623, 1599, 1474 (CdN, CdC, N-H). H NMR
DMSO-d ) δ: 0.80 (t, 3H, CH(CH )CH CH ), 1.05 (d, 3H, CH-
CH )CH ), 1.45 (q, 2H, CH(CH )CH CH ), 3.80 (m, 1H,
)CH ), 6.10 (bd, 1H, NHCH(CH )), 7.15 (d, 1H,
DMSO-d . Chemical shifts are reported in δ units (ppm) with
6
6
3
2
3
HMDS as an internal standard. The abbreviations s ) singlet,
d ) doublet, t ) triplet, m ) multiplet, and b ) board are
used throughout. Elemental analyses were realized on a Carlo-
Erba EA 1108 elemental analyzer.
3
2
CH
3
3
2
3
CH(CH
3
2
CH
3
3
8
-H), 7.50 (dd, 1H, 7-H), 7.70 (d, 1H, 5-H), 10.65 (bs, 1H, NH).
Anal. (C12 O‚H O): C, H, N.
-Ch lor o-2-R,S-(3-m et h yl-2-b u t yla m in o)q u in a zolin -
(3H)-on e Mon oh yd r a te (15). The title compound was
H
14ClN
3
2
6
-Chlor o-1,2-dih ydr o-2-thioxoquin azolin-4(3H)-one (10a).
6
A suspension of 5-chloroanthranilic acid (9a ) (10 g, 0.058 mol)
in thionyl chloride (40 mL) was heated at reflux for 1.5 h. After
removal of the excess of thionyl chloride under reduced
pressure, the residue was treated three times by dissolution
4
obtained as described for 13 starting from 6-chloro-2-methyl-
sulfanylquinazolin-4(3H)-one (11) (0.5 g, 2.2 mmol) and 3-meth-
yl-2-butylamine (10 mL), except that the reaction mixture was
heated at 120 °C for 15 h (yield 0.35 g, 56%). Mp: 207-208
2 2
in CH Cl (20 mL) and concentration. The crude acid chloride
was dissolved in acetone (10 mL), and this solution was added,
under stirring, to a solution of ammonium isothiocyanate (4.5
g, 0.060 mol) in acetone (20 mL). The reaction mixture was
stirred at room temperature for 30 min. The resulting pre-
cipitate was collected by filtration and dissolved in 10% w/v
NaOH in water (50 mL). The solution was treated with
charcoal and filtered. The filtrate was conducted to pH 2 with
°
C. IR (KBr): 3233 (N-H), 1675 (CdO), 1623, 1600, 1474 (Cd
1
N, CdC, N-H). H NMR (DMSO-d
CH(CH ), 1.00 (d, 3H, CH(CH )CH(CH
CH )CH(CH ), 3.80 (m, 1H, CH(CH )CH(CH
NHCH(CH )), 7.20 (d, 1H, 8-H), 7.50 (dd, 1H, 7-H), 7.70 (d,
H, 5-H), 10.80 (bs, 1H, NH). Anal. (C13 O‚H O): C,
H, N.
6
) δ: 0.80 (d, 6H, CH(CH
), 1.70 (m, 1H,CH-
), 6.10 (b, 1H,
3
)-
3
)
2
3
3 2
)
(
3
3
)
2
3
3 2
)
3
1
H
16ClN
3
2
2
N HCl, and the final product (9), which precipitated, was
collected by filtration, washed with water, and dried (yield 6.54
6-Ch lor o-2-[(cycloh e xyl)m e t h yla m in o)]q u in a zolin -
4(3H)-on e (16). A solution of 6-chloro-2-methylsulfanylquinazo-
lin-4(3H)-one (11) (0.4 g, 1.8 mmol) and cylcohexylamine (0.4
mL) in 3-chlorotoluene (4 mL) was heated under reflux for 1.5
h. After cooling, the reaction mixture was supplemented with
cyclohexane (20 mL). The crude precipitate was collected by
filtration, washed with cyclohexane and dried. This precipitate
was suspended in a mixture of water and ethanol (1:1), and a
10% w/v solution of NaOH in water was added until a near
complete solubilization occurred. After treatment with charcoal
and filtration, the filtrate was adjusted to pH 4-5 with 2 N
HCl. The precipitate was collected by filtration, washed with
water, and dried (yield 0.26 g, 50%). Mp: 278-279 °C. IR
g, 53%). Mp: >300 °C. IR (KBr): 3078 (N-H), 1707 (CdO),
1
1
7
619, 1562, 1462 (CdN, CdC, N-H). H NMR (DMSO-d
6
) δ:
.30 (d, 1H, 8-H), 7.70 (d, 1H, 7-H), 7.75 (s, 1H, 5-H), 12.60
ClN OS): C, H, N, S.
-Iodo-1,2-dih ydr o-2-th ioxoqu in a zolin -4(3H)-on e (10b).
The title compound was obtained from 5-iodoanthranilic acid
9b) (15 g, 0.057 mol) by following the same experimental
(bs, 1H, NH). Anal. (C
8
H
5
2
6
(
conditions as for 6-chloro-1,2-dihydro-2-thioxoquinazolin-4(3H)-
one (9) (yield 13.17 g, 76%). Mp: >300 °C. IR (KBr): 3105 (N-
1
H), 1698 (CdO), 1613, 1552, 1459 (CdN, CdC, N-H). H NMR
(
6
DMSO-d ) δ: 7.10 (d, 1H, 8-H), 7.90 (d, 1H, 7-H), 8.05 (s, 1H,
5
-H), 12.55 (bd, 1H, NH). Anal. (C
-Ch lor o-2-m et h ylsu lfa n ylqu in a zolin -4(3H )-on e (11).
To a solution of 10a (5 g, 0.023 mol) in 1% w/v NaOH in water
50 mL) were added methyl iodide (5 mL) and methanol (50
8 5 2
H IN OS): C, H, N, S.
6
(KBr): 3234 (N-H), 1675 (CdO), 1623, 1549, 1474 (CdN, Cd
1
C, N-H). H NMR (DMSO-d
6
) δ: 0.65-1.90 (m, 11H, C
6
H
11),
11), 7.10 (d,
1H, 8-H), 7.45 (dd, 1H, 7-H), 7.70 (d, 1H, 5-H), 10.70 (bs, 1H,
NH). Anal. (C15 O): C, H, N.
(
2 6 2 6
3.10 (m, 2H, CH C H11), 6.20 (b, 1H, NHCH C H
mL). The reaction mixture was stirred at room temperature
for 1 h. The resulting suspension was adjusted to pH 7 with 1
N HCl, and methanol was removed under reduced pressure.
After cooling, the title product, which was in suspension, was
collected by filtration, washed with water, and dried (4.8 g,
yield 90%). Mp: 219-221 °C. IR (KBr): 3154 (N-H), 1673 (Cd
H
18ClN
3
6-Ch lor o-2-[R-(1-cycloh exyl)et h yla m in o]q u in a zolin -
4(3H)-on e Mon oh yd r a te (17). The title compound was
obtained as described for 16 starting from 6-chloro-2-methyl-
sulfanylquinazolin-4(3H)-one (11) (0.5 g, 2.2 mmol) and R-1-

2
-Alkylamino-6-halogenoquinazolin-4(3H)-ones
J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16 2583
cyclohexylethylamine (0.5 mL). The reaction mixture was
CH
CH
3
), 1.50 (m, 2H, CH(CH
), 7.20 (d, 1H, 8-H), 7.50 (bm, 1H, NHCHCH
O‚H O): C, H, N.
-Iodo-2-R,S-(3-m eth yl-2-bu tylam in o)qu in azolin -4(3H)-
on e (24). A solution of 6-iodo-2-methylsulfanylquinazolin-
(3H)-one (12) (0.5 g, 1.6 mmol) in 3-methyl-2-butylamine (7
3
)CH
2
CH
3
), 4.00 (m, 1H, CH(CH
3 2
)CH -
heated at reflux for 3 h (yield 0.32 g, 45%). Mp: 242-244 °C.
3
3
), 7.85 (d,
IR (KBr): 3360 (N-H), 1660 (CdO), 1628, 1521, 1462 (CdN,
1H, 7-H), 8.10 (s, 1H, 5-H). Anal. (C12
6
H
14IN
3
2
1
CdC, N-H). H NMR (DMSO-d
6
) δ: 0.75-1.90 (bm, 11H,
11), 3.85 (m, 1H, CH(CH )-
)C 11), 7.15 (d, 1H, 8-H), 7.50
C
C
6
H
11), 1.00 (d, 3H,CH(CH
11), 6.15 (bd, 1H, NHCH(CH
3
)C
6
H
3
6
H
3
6
H
4
(d, 1H, 7-H), 7.75 (s, 1H, 5-H), 10.65 (bs, 1H, NH). Anal.
mL) was heated in an hermetically closed autoclave at 140 °C
for 3 h. The excess of amine was removed by distillation under
reduced pressure. The crude product was mixed with fresh
amine (5 mL) and heated in an autoclave at 140 °C for 6 h.
The excess reactant was removed by distillation under reduced
pressure. The residue was triturated with water (20 mL). The
resulting suspension was supplemented with a 10% w/v
aqueous solution of NaOH until dissolution. After clarification
with activated charcoal and filtration, the solution was ad-
justed to pH 5 with formic acid. The title compound was
collected by filtration, washed with water, and dried (yield 0.25
g, 45%). Mp: 219-221 °C. IR (KBr): 3397 (N-H), 1691 (Cd
O), 1625, 1598, 1466 (CdN, CdC, N-H). H NMR (DMSO-d
δ: 0.85 (d, 6H, CH(CH
(CH ), 1.65 (m,1H, CH(CH
CH(CH ), 6.10 (bd, 1H, NHCH(CH
(C
16
H
20ClN
3
O‚H
2
O): C, H, N.
6
-Ch lor o-2-[S-(1-cycloh exyl)et h yla m in o]q u in a zolin -
4
(3H)-on e Mon oh yd r a te (18). The title compound was
obtained as described for 16 starting from 6-chloro-2-methyl-
sulfanylquinazolin-4(3H)-one (11) (0.4 g, 1.8 mmol) and S-1-
cyclohexylethylamine (0.5 mL). The reaction mixture was
heated at reflux for 3 h (yield 0.31 g, 55%). Mp: 233-236 °C.
IR (KBr): 3265 (N-H), 1660 (CdO), 1628, 1521, 1463 (CdN,
1
CdC, N-H). H NMR (DMSO-d
6
) δ: 0.75-1.90 (bm, 11H,
11), 3.85 (m, 1H, CH(CH )-
)C 11), 7.20 (d, 1H, 8-H), 7.50
20ClN O‚H O): C,
C
C
6
H
11), 1.00 (d, 3H,CH(CH
11), 6.35 (bd, 1H, NHCH(CH
3
)C
6
H
3
6
H
3
6
H
1
(
d, 1H, 7-H), 7.75 (s, 1H, 5-H). Anal. (C16
H, N.
-Ch lor o-2-ben zyla m in oqu in a zolin -4(3H)-on e (19). The
title compound was obtained as described for 16 starting from
-chloro-2-methylsulfanylquinazolin-4(3H)-one (11) (0.5 g, 2.2
H
3
2
6
)
3
)CH(CH
3
)
2
), 1.00 (d, 3H, CH(CH
3
)CH-
), 3.80 (m,1H, CH(CH )-
)), 6.95 (d, 1H, 8-H), 7.70
6
3
)
2
3
)CH(CH
3
)
2
3
3 2
)
3
6
(dd, 1H, 7-H), 8.00 (d, 1H, 5-H), 10.60 (bs, 1H, NH). Anal.
3
(C13H16IN O): C, H, N.
mmol) and benzylamine (0.5 mL). The reaction mixture was
heated at reflux for 1.5 h (yield 0.36 g, 57%). Mp: 254-256
6-Iod o-2-[(cycloh exyl)m eth yla m in o]qu in a zolin -4(3H)-
on e (25). A solution of 6-iodo-2-methylsulfanylquinazolin-
4(3H)-one (12) (0.8 g, 2.5 mmol) and cylcohexylamine (1.6 mL)
in m-chlorotoluene (8 mL) was heated at reflux for 1.5 h. After
cooling, the reaction mixture was supplemented with cyclo-
hexane (20 mL). The crude precipitate was collected by
filtration, washed with cyclohexane and dried. The solid was
dissolved in a hydromethanolic (1:1) solution of 5% w/v NaOH.
After treatment with activated charcoal and filtration, the
solution was adjusted to pH 5 with formic acid. (yield 0.38 g,
°
C. IR (KBr): 3357 (N-H), 1666 (CdO), 1625, 1520, 1462 (Cd
1
N, CdC, N-H). H NMR (DMSO-d
6
) δ: 4.45 (d, 2H, CH
), 7.05-7.40 (m, 6H,C + 8-H) 7.45 (dd,
H, 7-H), 7.70 (d, 1H, 5-H). Anal. (C15 O): C, H, N.
-Ch lor o-2-[R-(1-p h en yl)eth yla m in o]qu in a zolin -4(3H)-
2 6 5
C H ),
6
1
.80 (m,1H, NHCH
2
6 5
H
12ClN
3
H
6
on e Hem ih yd r a te (20). The title compound was obtained as
described for 16 starting from 6-chloro-2-methylsulfanylquinazo-
lin-4(3H)-one (11) (0.5 g, 2.2 mmol) and R-1-(phenyl)ethyl-
amine (0.5 mL). The reaction mixture was heated at reflux
for 1.5 h (yield 0.27 g, 40%). Mp: 233-235 °C. IR (KBr): 3260
40%). Mp: 269-271 °C. IR (KBr): 3364 (N-H), 1689 (CdO),
1
1
(
N-H), 1677 (CdO), 1626, 1572, 1472 (CdN, CdC, N-H). H
1625, 1523, 1459 (CdN, CdC, N-H). H NMR (DMSO-d
6
) δ:
11), 6.40 (bt,
11), 6.95 (d, 1H, 8-H), 7.70 (bd, 1H, 7-H), 8.05
NMR (DMSO-d
CH(CH )C ), 6.80 (bd, 1H, NHCH(CH
+ 8-H + 7-H), 7.70 (d, 1H, 5-H). Anal. (C16
O): C, H, N.
-Ch lor o-2-[S-(1-p h en yl)eth yla m in o]qu in a zolin -4(3H)-
6
) δ: 1.40 (d, 3H, CH(CH
3
)C
)), 7.10-7.60 (m, 7H,
O‚
6
H
5
), 5.10 (bm, 1H,
0.75-1.90 (bm, 11H, C
6 2 6
H11), 3.10 (t, 2H, CH C H
H
5
3
1H, NHCH
2
C
6
H
3
6
C
6
H
5
H
14ClN
3
3
(bs, 1H, 5-H), 10.40 (bs, 1H, NH). Anal. (C15H18IN O): C, H,
N.
1
/
2
H
2
6
6-Iod o-2-ben zyla m in oqu in a zolin -4(3H)-on e (26). The
title compound was obtained as described for 25 starting from
6-iodo-2-methylsulfanylquinazolin-4(3H)-one (12) (0.8 g, 2.5
mmol) and benzylamine (1.5 mL). The reaction mixture was
heated at reflux for 1.5 h (yield 0.42 g, 45%). Mp: 274-276
on e Mon oh yd r a te (21). The title compound was obtained as
described for 16 starting from 6-chloro-2-methylsulfanylquinazo-
lin-4(3H)-one (11) (0.5 g, 2.2 mmol) and S-1-(phenyl)ethyl-
amine (0.5 mL). The reaction mixture was heated at reflux
for 1.5 h (yield 0.30 g, 43%). Mp: 222-224 °C. IR (KBr): 3262
°C. IR (KBr): 3424 (N-H), 1691 (CdO), 1627, 1599, 1465 (Cd
1
1
(
N-H), 1675 (CdO), 1630, 1548, 1471 (CdN, CdC, N-H). H
N, CdC, N-H). H NMR (DMSO-d
6
) δ: 4.50 (m, 2H, CH
2
C
6
H
5
),
), 7.70
(bd, 1H, 7-H), 8.10 (bs, 1H, 5-H), 10.90 (bs, 1H, NH). Anal.
O): C, H, N.
NMR (DMSO-d
CH(CH )C ), 6.80 (bd, 1H, NHCH(CH
+ 8-H), 7.60 (dd, 1H, 7-H), 7.70 (bd, 1H, 5-H). Anal.
O‚ H O): C, H, N.
6
) δ: 1.40 (d, 3H, CH(CH
3
)C
6
H
5
), 5.10 (bm, 1H,
2 6 5
6.80 (m,1H, NHCH ), 7.00 (d,1H, 8-H), 7.50 (m, 5H, C H
3
6
H
5
3
)), 7.10-7.50 (m, 6H,
C
6
H
5
(C15
H
12IN
3
(C
16
H
14ClN
3
2
Deter m in a tion of th e Op tica l P u r ity. Four 6-chloro-
quinazolin-4-ones bearing an asymmetric carbon atom on the
side chain in the 2-position (17, 18, 20, 21) were obtained by
reaction of 6-chloro-2-methylsulfanylquinazolin-4-one (11) with
pure R- and S-(1-cyclohexyl)ethylamine or (1-phenyl)ethyl-
amine commercially available from Sigma-Aldrich. To control
the absence of epimerization reactions, the purity of the final
products was assessed by high-pressure liquid chromatography
on a Merck-Hitachi apparatus (L6000 pump, L4000 UV
detector, and T2000 integrator) equipped with a CHIRALCEL
OD-R column. Chromatographic conditions were as follows:
6
-Iod o-2-isop r op yla m in oqu in a zolin -4(3H)-on e (22). A
solution of 6-iodo-2-methylsulfanylquinazolin-4(3H)-one (12)
0.5 g, 1.6 mmol) in isopropylamine (7 mL) was heated in an
(
autoclave at 150 °C for 5 h. The excess of amine was removed
under reduced pressure, and the residue was triturated with
water (35 mL). The resulting precipitate was dissolved in a
1
0% w/v aqueous solution of NaOH. After clarification with
activated charcoal and filtration, the filtrate was adjusted to
pH 5 with formic acid. The title compound was collected by
filtration, washed with water, dried, and recrystallized from
hot methanol (yield 0.21 g, 41%). Mp: 258-260 °C. IR (KBr):
6
mobile phase, 50 mM KPF in water/acetonitrile (in %: 40/60
3
255 (N-H), 1681 (CdO), 1625, 1591, 1466 (CdN, CdC,
for 17, 18 and 45/55 for 20, 21); flow rate, 0.5 mL/min;
temperature, 25 °C; sample concentration, 0.2 mg/mL; injection
volume, 5.0 µL; detection, UV at 225 nm. Results expressed
as the enantiomeric excesses were calculated from the follow-
ing equation: for the R-isomer: ee % ) [(peak surface of R -
peak surface of S)/(peak surface of R + peak surface of S)]; for
the S-isomer: ee % ) [(peak surface of S - peak surface of
R)/(peak surface of R + peak surface of S)]. Results reported
are the means of two individual determinations.
1
N-H). H NMR (DMSO-d
m, 1H, CH(CH ), 6.10 (bs, 1H, NHCH(CH
-H), 7.70 (bd, 1H, 7-H), 8.05 (bs, 1H, 5-H), 10.6 (bs, 1H, NH).
Anal. (C11 O): C, H, N.
-Iodo-2-R,S-(2-bu tylam in o)qu in azolin -4(3H)-on e Mon o-
6
) δ: 1.10 (d, 6H, CH(CH
3 2
) ), 4.00
(
8
3
)
2
3 2
)
), 7.00 (bd, 1H,
H
12IN
3
6
h yd r a te (23). The title compound was obtained as described
for 22 starting from 6-iodo-2-methylsulfanylquinazolin-4(3H)-
one (12) (0.5 g, 1.6 mmol) and 2-butylamine (10 mL) (yield
0
.25 g, 44%). Mp: 235-236 °C. IR (KBr): 3264 (N-H), 1679
Biologica l a ssa ys. Mea su r em en ts of In su lin Relea se
fr om In cu ba ted Ra t P a n cr ea tic Islets. All experiments
were performed with islets isolated from fed Wistar rats (180-
1
(CdO), 1632, 1546, 1467 (CdN, CdC, N-H). H NMR (DMSO-
d
6
) δ: 0.85 (t, 3H, CH(CH )CH CH ), 1.10 (d, 3H, CH(CH )CH
3
2
3
3
2
-

2
584 J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16
Somers et al.
2
20 g). Groups of 10 islets, each derived from the same batch
salt medium supplemented with 0.5% (w/v) dialyzed albumin
of islets, were preincubated for 30 min at 37 °C in 1 mL of a
physiological salt medium (in mM: NaCl 115, KCl 5, CaCl
.56, MgCl 1, NaHCO 24) supplemented with 2.8 mM
glucose, 0.5% (w/v) dialyzed albumin and equilibrated against
a mixture of O (95%) and CO (5%). The islets were incubated
2 2
and gassed with O (95%) and CO (5%). Groups of 100 islets
2
were incubated for 60 min in a medium containing 16.7 mM
glucose and either 86Rb (0.15-0.25 mM; 50 µCi/mL) or Ca
(0.02-0.04 mM; 100 µCi/mL). After incubation, the islets were
washed three times and then placed in a perifusion chamber.
The perifusate was delivered at a constant rate (1 mL/min).
From the 31st to the 90th min, the effluent was continuously
collected over successive periods of 1 min each. An aliquot of
the effluent (0.6 mL) was used for scintillation counting. At
the end of the perifusion, the radioactive content of the islets
was also determined. The outflow of 86Rb or Ca was expressed
as a fractional outflow rate (% of instantaneous islets content/
45
2
2
3
2
2
at 37 °C for a further 90 min in 1 mL of the same medium
containing 16.7 mM glucose and, in addition, the quinazolinone
derivatives. The release of insulin was measured radioimmu-
3
2
nologically using rat insulin as a standard.
Mea su r em en ts of Con tr a ctile Activity in Ra t Aor ta .
All experiments were performed in aorta removed from Fed
Wistar rats (body weight 250-300 g). A section of the aorta
was cleared of adhering fat and connective tissue and was cut
into transverse rings (3-4 mm long). The endothelium was
removed by rubbing the intimal surface with forceps. The
segments were suspended under 2 g of tension by means of
steel hooks in an organ bath containing 20 mL of Krebs-
bicarbonate-buffered solution of the following composition (in
45
min; FOR). The validity of 8 Rb as a substitute for K has
6
42
been previously established.1
1,17
Cr ysta l Str u ctu r e Deter m in a tion of 13. Crystal was
grown by slow evaporation from methanol. Diffraction data
were measured at room temperature using a Stoe-Siemens
AED four-circle diffractometer. Final cell dimensions were
obtained by a least-squares fit to the automatically centered
setting for 30 reflections (51.23 < 2θ < 79.70°). Two reference
reflections monitored during each experiment showed no
significant variation. Intensity data were corrected for Lorentz
polarization effects and for absorption (semiempirical method,
ψ scan). Space group assignment was suggested by cell
geometry and average values of the normalized structure
factors; choice was confirmed by successful refinement.
mM): NaCl 118, KCl 4.7, CaCl
MgSO 1.2, glucose 5. The physiological solutions were main-
tained at 37 °C and bubbled continuously with a mixture of
(95%) and CO (5%). The isometric contractions of the aortic
2 3 2 4
2.5, NaHCO 25, KH PO 1.2,
4
O
2
2
rings were measured with a force-displacement transducer.
After 60 min of equilibration, the rings were exposed to 30
mM or 80 mM KCl. When the tension had stabilized, the drugs
were added at increasing concentrations until maximal relax-
ation. The same experiments were repeated in the presence
of glibenclamide throughout (1 and 10 µM). The relaxation
response was expressed as the percentage of the contractile
response to KCl. The IC50 value was graphically assessed for
each dose response curve as the concentration evoking 50%
inhibition of the plateau induced by KCl. Results were
expressed as the means (( SEM) of 4-12 experiments.
Mea su r em en ts of Con tr a ctile Activity in Gu in ea P ig
Ileu m . Adult guinea pigs (body weight 300-400 g) were
stunned and bled. Segments of the ileum (4 cm long) were
removed at least 10 cm from the caecum. They were set up
under an initial load of 1 g in a Krebs-bicarbonate-buffered
solution of the following composition (in mM): NaCl 118, KCl
3
4
The structure was solved by direct methods (SHELXS-97 ).
The non-hydrogen atoms were refined anisotropically (SHELXL-
3
5
9
7 ). H atoms have been included in the refinement as riding
atoms at calculated positions except those involved in hydrogen
bonds of which positions were refined. There were two
independent molecules in the asymmetric unit. The final
difference Fourier map had no significant features. Atomic
scattering factors were taken from ref 36. The thermal ellipsoid
views of 13 (molecules A and B) was undertaken with program
ORTEP-III.37
Ack n ow led gm en t. This study was supported by
grants from National Fund for Scientific Research
(F.N.R.S. Belgium) of which P. Lebrun is Research
4
5
.7, CaCl
, maintained at 37 °C and gassed with a mixture of O
(5%). Coaxial stimulation was carried out as described
2
2.5, NaHCO
3
25, KH
2
PO
4
1.2, MgSO
4
1.2, glucose
Director and P. de Tullio and B. Pirotte are Senior
Research Associates. B. Becker and R. Ouedraogo were
supported by a grant-in-aid from the Universit e´ Libre
de Bruxelles. The assistance of M. Hermann, Mrs. P.
Neven, D. Dewalque, M. L. Pirard, M. Vermeire, and J .
Sergooris is gratefully acknowledged.
2
(95%)
and CO
2
3
3
by Paton with rectangular pulses of 0.5 ms duration, 0.1 Hz,
-25 V. Muscle contractions were recorded isometrically. The
5
inhibitory effects of drugs were assessed on electrically induced
contractions by adding increasing concentrations until maxi-
mal effect. Results were expressed as percentage of control
responses (measured during 5 min before adding the drug).
IC50 values (means ( SEM) were graphically assessed.
Mea su r em en ts of Con tr a ctile Activity in Ra t Uter u s.
Fed Wistar rats (body weight 150-200 g) were treated the day
before killing with diethylstilboestrol dipropionate [i.m. injec-
tion of 0.1 mL/100 g of a 1 mg/mL oily solution of diethylstil-
boestrol dipropionate (Sigma)]. The rats were anesthetized and
then sacrified. The two uterine horns were removed, cleared
of adhering fat and connective tissue, and separated. Each
horn was superfused with a Tyrode solution (in mM: NaCl
Su p p or tin g In for m a tion Ava ila ble: Crystal data, final
atomic positional parameters, bond distances and angles,
atomic thermal parameters, hydrogen coordinates, torsion
angles, and hydrogen bonds for compound 13 (Tables 1-7).
This material is available free of charge via the Internet at
http://pubs.acs.org.
Refer en ces
(
1) Pirotte, B.; Fontaine, J .; Lebrun, P. Recent Advances in the
Chemistry of Potassium Channel Openers. Curr. Med. Chem.
1995, 2, 573-582.
1
0
O
37, KCl 2.7, CaCl
.4, glucose 5.6) and bubbled continuously with a mixture of
(95%) and CO (5%). The superfusate was maintained at
7 °C. Injections of 20 mU oxytocin (200 µL of a 0.1 U/mL
2 2 3 2 4
1.8, MgCl 1.1, NaHCO 11.9, NaH PO
(2) Edwards, G.; Weston, A. H. The Pharmacology of ATP-Sensitive
Potassium Channels. Annu. Rev. Pharmacol. Toxicol. 1993, 33,
2
2
5
97-637.
3
(
3) Ashcroft, F. M. Adenosine-5′-triphosphate-sensitive Potassium
Channels. Annu. Rev. Neurosci. 1988, 11, 97-118.
+
solution of the hormone in 0.9% NaCl) in the superfusion
channel were repeated at 10 min intervals until the recorded
contractions (AUC) were constant. The mean of the three last
injections gave the 100% of the contractile response to oxytocin.
For each drug concentration added in the medium, injection
of 20 mU oxytocin was repeated at least three times. The
contractile responses recorded (mean of three AUC) were
expressed as a percentage of the reference value (contractile
response to oxytocin in the absence of drug).
(4) Lebrun, P.; Antoine, M.-H.; Herchuelz, A. Minireview:
K
Channel Openers and Insulin Release. Life Sci. 1992, 51, 795-
8
06.
(
5) Kolb, H. A. Potassium Channels in Excitable and Non-Excitable
Cells. Rev. Physiol. Biochem. Pharmacol. 1990, 15, 51-79.
6) Malaisse, W. J .; Lebrun, P. Mechanisms of Sulfonylurea-Induced
Insulin Release. Diabetes Care 1990, 13 (Suppl 3), 9-17.
(
(7) Robertson, D. W.; Steinberg, M. I. Potassium Channels Modula-
tors: Scientific Application and Therapeutic Promise. J . Med.
Chem. 1990, 33, 1529-1541.
Mea su r em en ts of 86Rb a n d 45Ca Ou tflow fr om P er i-
fu sed Ra t P a n cr ea tic Islets. The media used for incubating,
washing, and perifusing the islets consisted of a physiological
(
8) Longman, S. D.; Hamilton, T. C. Potassium Channel Activator
Drugs: Mechanism of Action, Pharmacological Properties and
Therapeutic Potential. Med. Res. Rev. 1992, 12, 73-148.

2
-Alkylamino-6-halogenoquinazolin-4(3H)-ones
J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 16 2585
(
9) Weston, A. H.; Edwards, G. Recent Progress in Potassium
(22) Erb, B.; Akue, R.; Rigo, B.; Pirotte, B.; Couturier, D.; Synthesis
of 2-Aminoquinazolin-4(3H)-ones as Potential Potassium Chan-
nel Openers. J . Heterocycl. Chem. 2000, 37, 253-260.
(23) Lebrun, P.; Devreux, V.; Hermann, M.; Herchuelz, A. Pinacidil
Inhibits Insulin Release by Increasing K+ Outflow from Pan-
creatic B-cells. Eur. J . Pharmacol. 1988, 156, 283-286.
(24) Quayle, J . M.; Nelson, M. T.; Standen, N. B. ATP-sensitive and
Inwardly Rectifying Potassium Channels in Smooth Muscle.
Physiol. Rev. 1997, 77, 1165-1232.
Channel Opener Pharmacology. Biochem. Pharmacol. 1992, 43,
4
7-54.
(
(
(
(
10) Antoine, M.-H.; Berkenboom, G.; Fang, Z.-Y.; Fontaine, J .;
Herchuelz, A.; Lebrun, P.; Mechanical and Ionic Response of
Rat Aorta to Diazoxide. Eur. J . Pharmacol. 1992, 216, 299-
3
06.
11) Lebrun, P.; Devreux, V.; Hermann, M.; Herchuelz, A. Similarities
Between the Effects of Pinacidil and Diazoxide on Ionic and
Secretory Events in Rat Pancreatic Islets. J . Pharmacol. Exp.
Ther. 1989, 250, 1011-1018.
(25) Sun, Y. D.; Benishin, C. G. K+ Channel Openers Relax Longi-
tudinal Muscle of Guinea Pig Ileum. Eur. J . Pharmacol. 1994,
271, 453-459.
12) Lebrun, P.; Antoine, M. H.; Devreux, V.; Hermann, M.; Her-
8
6
chuelz, A. Paradoxical Inhibitory Effect of Cromakalim on Rb
(26) Davies, M. P.; McCurrie, J . R.; Wood, D. Comparative Effects of
+
Outflow from Pancreatic Islet Cells. J . Pharmacol. Exp. Ther.
K
Channel Modulating Agents on Contractions of Rat Intestinal
1
990, 255, 948-953.
Smooth Muscle. Eur. J . Pharmacol. 1996, 297, 249-256.
(27) Lebrun, P.; Arkhammar, P.; Antoine, M.-H.; Nguyen, Q.-A.;
Bondo-Hansen, J .; Pirotte, B. A Potent Diazoxide Analogue
Activating ATP-sensitive K+ Channels and Inhibiting Insulin
Release. Diabetologia 2000, 43, 723-732.
(28) Ouedraogo, R.; Fontaine, J .; Antoine, M.-H.; Pirotte, B.; Lebrun,
P. Effects of 3-Alkylamino-7-chloro-4H-pyrido[2,3-e]-1,2,4-thia-
diazine 1,1-Dioxides on Smooth Muscle Contraction. Pharm.
Pharmacol. Commun. 2000, 6, 97-100.
(29) Pirotte, B.; Ouedraogo, R.; de Tullio, P.; Khelili, S.; Somers, F.;
Boverie, S.; Dupont, L.; Fontaine, J .; Damas, J .; Lebrun, P.
3-Alkylamino-4H-pyrido[2,3-e]-1,2,4-thiadiazine 1,1-Dioxides
Structurally Related to Diazoxide and Pinacidil as Potassium
Channel Openers Acting on Vascular Smooth Muscle Cells:
Design, Synthesis and Pharmacological Evaluation. J . Med.
Chem. 2000, 43, 1456-1466.
(30) Bandoli, G.; Nicolini, M. Crystal and Molecular Structure of
Diazoxide an Antihypertensive Agent. J . Cryst. Mol. Struct.
1977, 7, 229-240.
(31) Pirotte, B.; de Tullio, P.; Masereel, B.; Schynts, M.; Delarge, J .
Structural Study of Pinacidil, a Potassium Channel Opener
Belonging to the Chemical Class of N-alkyl-N′′-cyano-N′-py-
ridylguanidines. Helv. Chim. Acta 1993, 16, 1311-1318.
(32) Leclercq-Meyer, V.; Marchand, J .; Woussen-Colle, M. C.; Giroix,
M.-H.; Malaisse, W. J . Multiple Effects of Leucine on Glucagon,
Insulin, and Somatostatin Secretion from the Perfused Rat
Pancreas. Endocrinology 1985, 116, 1168-1174.
(33) Paton, W. D. M. The Response of Guinea Pig Ileum to Electrical
Stimulation by Coaxial Electrodes. J . Physiol. 1955, 127, 40P-
41P.
(34) Sheldrick, G. M. SHELXS 97, A Program for the Solution of
Crystal Structures; University of G o¨ ttingen: G o¨ ttingen, Ger-
many, 1997.
13) Lebrun, P.; Fang, Z. Y.; Antoine, M. H.; Herchuelz, A.; Hermann,
M.; Berkenboom, G.; Fontaine, J . Hypoglycemic Sulfonylureas
Antagonize the Effects of Cromakalim and Pinacidil on 86Rb
Fluxes and Contractile Activity in the Rat Aorta. Pharmacology
1
990, 41, 36-48.
(
14) Pirotte, B.; de Tullio, P.; Lebrun, P.; Antoine, M. H.; Fontaine,
J .; Masereel, B.; Schynts, M.; Dupont, L.; Herchuelz, A.; Delarge,
J . 3-(Alkylamino)-4H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-Dioxides
as Powerful Inhibitors of Insulin Release From Rat Pancreatic
B-cells: a New Class of Potassium Channel Openers? J . Med.
Chem. 1993, 36, 3211-3213.
(
15) De Tullio, P.; Pirotte, B.; Lebrun, P.; Fontaine, J .; Dupont, L.;
Antoine, M.-H.; Ouedraogo, R.; Khelili, S.; Maggetto, C.; Ma-
sereel, B.; Diouf, O.; Podona, T. Delarge, J . 3- and 4-Substituted
4
H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-Dioxides as Potassium
Channel Openers: Synthesis, Pharmacological Evaluation and
Structure-activity Relationships. J . Med. Chem. 1996, 39, 937-
9
48.
(16) Pirotte, B.; Antoine, M.-H.; de Tullio, P.; Hermann, M.; Her-
chuelz, A.; Delarge, J .; Lebrun, P. A Pyridothiadiazine (BPDZ
4
4) as a New and Potent Activator of ATP-sensitive K+ Channels.
Biochem. Pharmacol. 1994, 47, 1381-1386.
(17) Lebrun, P.; Antoine, M.-H.; Ouedraogo, R.; Dunne, M.; Kane,
C.; Hermann, M.; Herchuelz, A.; Masereel, B.; Delarge, J .; de
+
Tullio, P.; Pirotte, B. Activation of ATP-dependent K Channels
and Inhibition of Insulin Release: Effect of BPDZ 62. J . Phar-
macol. Exp. Ther. 1996, 277, 156-162.
(
18) Antoine, M.-H.; Pirotte, B.; Hermann, P.; de Tullio, P.; Delarge,
J .; Herchuelz, A.; Lebrun, P. Cationic and Secretory Effects of
BPDZ 44 and Diazoxide in Rat Pancreatic Islets. Experientia
1
994, 50, 830-832.
(
19) Khelili, S.; de Tullio, P.; Lebrun, P.; Fillet, M.; Antoine, M.-H.;
Ouedraogo, R.; Dupont, L.; Fontaine, J .; Felekidis, A.; Leclerc,
G.; Delarge, J .; Pirotte, B. Preparation and Pharmacological
Evaluation of the R- and S-Enantiomers of 3-(2′-Butylamino)-
(35) Sheldrick G. M. SHELXL 97, A Program for the Refinement of
Crystal Structures from Diffraction Data. University of G o¨ ttin-
gen, G o¨ ttingen, Germany, 1997.
4
H- and 3-(3′-methyl-2′-butylamino)-4H-pyrido[4,3-e]-1,2,4-thia-
(36) International Tables for X-ray Crystallography; Hahn, Th., Ed.;
Reidel Publishing Company: Dordrecht, The Netherlands, 1992;
Vol. C, Tables 4.2.6.8 and 6.1.1.4.
(37) Burnett, M. N.; J ohnson, C. K. ORTEP-III; Oak Ridge Thermal
Ellipsoid Plot Program for Crystal Structure Illustrations.
Report ORNL-6895; Oak Ridge National Laboratory: Oak Ridge,
TN, 1996.
diazine 1,1-Dioxide, Two Tissue Selective ATP-sensitive Potas-
sium Channel Openers. Bioorg. Med. Chem. 1999, 7, 1513-
1
520.
(
20) Hess, H. J .; Cronin, T. H.; Scriabine, A. Antihypertensive
2
1
-amino-4(3H)-quinazolinones. J . Med. Chem. 1968, 11, 130-
37.
(21) Empfield, J . R.; Russell, K. Potassium Channel Openers. Annu.
Rep. Med. Chem. 1995, 30, 81-90.
J M0004648