(R)-(+)-2-[[[3-(morpholinomethyl)-2H-chromen-8-yl]oxy]methyl]morpholine methanesulfonate: A new selective rat 5-hydroxytryptormine(1b) receptor antagonist

Article abstract of DOI:10.1021/jm970806i

In the search for new 5-hydroxytryptamine (5-HT) receptor antagonists it was found that the compound (R)-(+)-2-[[[3-(morpholinomethyl)-2H-chromen-8- yl]oxy]methyl]morpholine methanesulfonate, (R)-25, is a selective rat 5- hydroxytryptamine(1B) (r5-HT(1B)) receptor antagonist. The binding profile showed a 13-fold preference for r5-HT(1B) (Ki = 47 ± 5 nM; n = 3) vs bovine 5-HT(1B) (Ki = 630 nM; n = 1) receptors. The compound had very low affinity for other monoaminergic receptors examined. The r5-HT(1B) receptor antagonism was demonstrated by the potentiation of the K⁺-stimulated release of [³H]- 5-HT from superfused rat brain slices in vitro, an effect that was antagonized by addition of 5-HT to the superfusion fluid. (R)-25 at 20 mg/kg sc enhanced the 5-HT turnover in four rat brain regions (hypothalamus, hippocampus, striatum, and frontal cortex) with about 40% measured as the 5- HTP accumulation after decarboxylase inhibition with 3- hydroxybenzylhydrazine. At 3 mg/kg sc (R)-25 produced a significant increase in the number of wet dog shakes in rats, a 5-HT(2A)/5-HT(2C) response that was abolished by depletion of 5-HT after pretreatment with the tryptophan hydroxylase inhibitor p-chlorophenylalanine. The observations show that (R)- 25, by inhibiting terminal r5-HT(1B) autoreceptors, increases the 5-HT turnover and the synaptic concentration of 5-HT.

Full text of DOI:10.1021/jm970806i

1934
J . Med. Chem. 1998, 41, 1934-1942
(R)-(+)-2-[[[3-(Mor p h olin om eth yl)-2H-ch r om en -8-yl]oxy]m eth yl]m or p h olin e
Meth a n esu lfon a te: A New Selective Ra t 5-Hyd r oxytr yp ta m in e1B Recep tor
An ta gon ist
Stefan Berg,*,§ Lars-Gunnar Larsson,† Lucy Re´nyi,† Svante B. Ross,† Seth-Olof Thorberg,§ and
Gun Thorell-Svantesson‡
Departments of Medicinal Chemistry, Behavioral and Biochemical Pharmacology, and Molecular Pharmacology,
Preclinical R&D, Astra Arcus AB, S-151 85 So¨derta¨lje, Sweden
Received December 1, 1997
In the search for new 5-hydroxytryptamine (5-HT) receptor antagonists it was found that the
compound (R)-(+)-2-[[[3-(morpholinomethyl)-2H-chromen-8-yl]oxy]methyl]morpholine meth-
anesulfonate, (R)-25, is a selective rat 5-hydroxytryptamine1B (r5-HT1B) receptor antagonist.
The binding profile showed a 13-fold preference for r5-HT1B (Ki ) 47 ( 5 nM; n ) 3) vs bovine
5-HT1B (Ki ) 630 nM; n ) 1) receptors. The compound had very low affinity for other
monoaminergic receptors examined. The r5-HT1B receptor antagonism was demonstrated by
the potentiation of the K+-stimulated release of [3H]-5-HT from superfused rat brain slices in
vitro, an effect that was antagonized by addition of 5-HT to the superfusion fluid. (R)-25 at 20
mg/kg sc enhanced the 5-HT turnover in four rat brain regions (hypothalamus, hippocampus,
striatum, and frontal cortex) with about 40% measured as the 5-HTP accumulation after
decarboxylase inhibition with 3-hydroxybenzylhydrazine. At 3 mg/kg sc (R)-25 produced a
significant increase in the number of wet dog shakes in rats, a 5-HT2A/5-HT2C response that
was abolished by depletion of 5-HT after pretreatment with the tryptophan hydroxylase
inhibitor p-chlorophenylalanine. These observations show that (R)-25, by inhibiting terminal
r5-HT1B autoreceptors, increases the 5-HT turnover and the synaptic concentration of 5-HT.
Ch a r t 1
In tr od u ction
Of the many 5-hydroxytryptamine (5-HT, serotonin)
receptors discovered,1 two subtypes of the 5-HT1 recep-
tor group appear to play important roles in the feedback
regulation of the activity in 5-HT neurons. Inhibitory
somatodendritic 5-HT1A receptors in the raphe´ nuclei
sense the concentration of 5-HT around the cell bodies.
Through these receptors the impulse propagation in the
5-HT neuron is regulated and thereby also the amount
of 5-HT being released at the nerve terminals.2 5-HT1B
autoreceptors located on the nerve terminals regulate
the synaptic concentration of 5-HT by controlling the
exocytotic release of 5-HT.3,4 The influence of the
somatodendritic 5-HT1A receptors on 5-HT neurotrans-
mission has been extensively studied with electrophysi-
ological and neurochemical techniques5-8 using selective
5-HT1A receptor agonists and antagonists. However, the
lack of selective ligands for the 5-HT1B receptors has
hampered studies of the functional role of the terminal
autoreceptors in the regulation of release of 5-HT.
Another impeding factor has been the species difference
in the terminal 5-HT autoreceptors between rodents and
most other species including man. Although the rodent
5-HT1B (r5-HT1B) receptor displays more than 90%
homology with the human h5-HT1B receptor, their
pharmacology is quite different.9 During recent years
an increasing interest has therefore been focused on
development of agonists and antagonists of the h5-HT1B
receptor, resulting in selective agonists, e.g., sumatrip-
tan,10 and antagonists, e.g., GR 127935.11 It was
observed earlier that some but not all â-adrenoceptor
antagonists, e.g., (-)-pindolol, (-)-cyanopindolol, (-)-
propranolol, and (-)-alprenolol, also antagonize the
5-HT1A and r5-HT1B receptors but have low affinities
for other 5-HT receptors.12 Other â-adrenoceptor an-
tagonists with high affinity for r5-HT1B are (-)-pen-
butulol13 and isamoltane.14,15
During our synthesis and screening for new selective
antagonists of the terminal 5-HT1B autoreceptor with
potential for antidepressive effect, we discovered that
one compound, R-(+)-2-[[[3-(morpholinomethyl)-2H-
chromen-8-yl]oxy]methyl]morpholine methanesulfonate,
NAS-181 ((R)-25) (Chart 1), is a selective r5-HT1B
receptor antagonist with interesting in vitro and in vivo
properties in rats.
Ch em istr y
Two key intermediates, described by the general
formula A and B (Scheme 5), were prepared and used
in the synthesis of (R)-(+)-2-[[[3-(morpholinomethyl)-2H-
chromen-8-yl]oxy]methyl]morpholine methanesulfonate
((R)-25) and its analogues.
§ Department of Medicinal Chemistry.
† Department of Behavioral and Biochemical Pharmacology.
‡ Department of Molecular Pharmacology.
S0022-2623(97)00806-6 CCC: $15.00 © 1998 American Chemical Society
Published on Web 04/29/1998

A New Selective Rat 5-HT1B Receptor Antagonist
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 11 1935
Sch em e 1a
Sch em e 2a
a
Reagents and conditions: (a) benzylamine; (b) chloroacetyl
chloride, TEA, CH2Cl2; (c) NaOCH3, methanol, ∆; (d) LAH, diethyl
ether; (e) Pd/C, H2, EtOH/HOAc, ∆; (f) trityl chloride, TEA, CH2Cl2;
(g) p-tosyl chloride, pyridine, CH2Cl2.
Sch em e 3a
a
Reagents and conditions: (a) trityl chloride, TEA, CH2Cl2; (b)
p-tosyl chloride, pyridine, CH2Cl2.
a
Reagents and conditions: (a) NaOCH3, ethyl formate, MeOH;
Sch em e 4a
(b) H2NOH‚HCl, HOAc, ∆; (c) NaOCH3, MeOH, 0 °C; (d) NaBH4,
MeOH; (e) PTS, toluene, ∆; (f) BBr3, CH2Cl2, rt; (g) BBr3, CH2Cl2,
-20 °C; (h) SOCl2, toluene, ∆; (i) morpholine, dioxane; (j) BBr3,
CH2Cl2, -20 °C; (k) LAH, AlCl3, THF, 0 °C.
The synthesis of the phenols 1, 7, 10 and 11 (A
intermediates in Scheme 5) is outlined in Scheme 1.
6-Cyano-7,8-dihydro-1-naphthol (1) was synthesized
starting from the commercially available 5-methoxy-1-
tetralone (2) which was transformed into the 2-hy-
droxymethylene derivative 3 by treatment with ethyl
formate and sodium methoxide. Treatment with hy-
droxylamine hydrochloride in acetic acid at reflux
followed by stirring in methanol in the presence of
sodium methoxide gave the nitrile 4. The keto group
was reduced with sodium borohydride, whereupon the
formed alcohol was dehydrated using a Dean-Stark
trap. The above synthesis was carried out by a slight
modification of a procedure previously described.16 The
methoxy group in derivative 5 was cleaved with boron
tribromide at room temperature to give the phenol 1 in
high yield.
The corresponding chromene 7 was prepared in one
step by demethylation of 8-methoxy-3-cyano-2H-chro-
mene (6)17 with boron tribromide at -20 °C in 92% yield.
8-Hydroxy-3-(N-morpholinomethyl)-2H-chromene (11)
was synthesized starting from 8-methoxy-2H-chromene-
3-carboxylic acid (8)17 which was converted to the acid
chloride by reaction with thionyl chloride. The acid
chloride was then reacted with morpholine to form the
amide 9 which was subsequently treated with boron
a
Reagents and conditions: (a) Pd/C, H2, HOAc; (b) iodomethane,
DMF.
tribromide at -20 °C to give the phenol 10. The amide
function in compound 10 was initially reduced with
lithium aluminum hydride in low yields, but it was
found that aluminum hydride18,19 was a superior reduc-
ing agent giving compound 11 in 96% yield.
The syntheses of the key intermediates 12, 19 and
22 (B intermediates in Scheme 5) are shown in Schemes
2-4, and they were performed as follows: The synthesis
of the enantiomers of (R,S)-2-[[(p-tolylsulfonyl)oxy]meth-
yl]-4-(triphenylmethyl)morpholine20 ((R,S)-12), (R)-12
and (S)-12, starts with a nucleophilic ring opening of
the glycidyl ether (R)-13 or (S)-13 using an excess of
benzylamine (Scheme 2). The amino alcohols 14 were
acylated using chloroacetyl chloride, and the formed
product was cyclized in methanol at reflux using sodium
methoxide to give the lactam 15 in approximately 90%
yield. The lactam 15 was reduced to the morpholine
compound 16 with lithium aluminum hydride in diethyl
ether at room temperature in high yield followed by
removal of the benzyl groups by hydrogenation over
palladium on activated carbon at 55-60 °C to give

1936 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 11
Berg et al.
Sch em e 5a
a
Reagents and conditions: (a) DMF, K2CO3, ∆; (b) where applicable HOAc/H2O.
Ta ble 1. Affinities of New Compounds for the r5-HT1B
Ta ble 2. Receptor Binding Profile of (R)-25 and Its Antipode
affinity, Ki, nM
Receptor in Membranes of Rat Cerebral Cortex Using
[
125I]Iodocyanopindolol as Ligand
receptor
5-HT1A
ligand
(R)-25
(S)-25
compd
Ki, nM ((SEM)
n
[3H]-8-OH-DPAT
>10 000 >10 000
630 >10 000
>3 000
(R,S)-25
(R)-25
(S)-25
(R,S)-26
(R,S)-27
(R,S)-28
(R,S)-29
(R,S)-30
60 ( 14
47 ( 5
275 ( 38
445
250 ( 50
3600
5
3
3
1
3
1
1
1
b5-HT1B + 5-HT1D [3H]-5-HT
5-HT6
5-HT7
5-HT2A
5-HT2C
[3H]-5-HT
[3H]-5-HT
>3 000
[3H]ketanserin
[3H]mesulergine
[3H]prazosin
[3H]RX821002
>10 000 >10 000
>10 000 >10 000
>10 000 >10 000
>10 000 >10 000
R1-adrenoceptor
R2-adrenoceptor
â-adrenoceptor
dopamine D1
dopamine D2
σ
1400
240
[3H]dihydroalprenolol >10 000
10 000
[3H]SCH 23390
[3H]raclopride
[3H]DTG
>10 000 >10 000
>10 000 >10 000
>10 000 >10 000
>1 000
compound 17 in a moderate yield. Protection of the
morpholine nitrogen with triphenylmethyl chloride gave
compound 18, and subsequent conversion of the alcohol
group to the tosylate gave compound 12 in good yield.
(R,S)-3-[[(p-Tolylsulfonyl)oxy]methyl]-1-(triphenyl-
methyl)piperidine (19) was synthesized from the com-
mercially available (R,S)-3-(hydroxymethyl)piperidine
(20) which was reacted with triphenylmethyl chloride
to give compound 21 and then finally tosylated (Scheme
3).
muscarinic
[3H]QNB
Ta ble 3. Potentiation of K+-Stimulated Release of [3H]-5-HT
from Brain Slices by (R)-25
concn,
nM
S2/S1
(mean ( SEM)
S2/S1,
% of control
n
Pa
0
10
100
1000
6
4
3
8
0.99 ( 0.03
1.11 ( 0.09
1.23 ( 0.11
1.44 ( 0.06
115 ( 3
131 ( 2
153 ( 6
>0.05
<0.05
<0.05
(R,S)-4-Methyl-2-[[(p-tolylsulfonyl)oxy]methyl]mor-
pholine (22) was prepared in two steps from (R,S)-4-
benzyl-2-[[(p-tolylsulfonyl)oxy]methyl]morpholine21 (23)
(Scheme 4). The benzyl group was removed by catalytic
hydrogenation at room temperature. Methylation of
compound 24 with iodomethane gave 22 in 71% yield.
The syntheses of the final compounds 25-30 (C) are
shown in Scheme 5. The phenols 1, 7, 10, and 11 were
alkylated with the tosylates (R,S)-12, (S)-12, (R)-12, 21,
and 22 yielding the desired products. In the cases
where applicable, the alkylation was followed by hy-
drolysis of the trityl group in acetic acid.
a
Versus the appropriate control (Student’s t-test).
The affinity of (R)-25 for the 5-HT1D receptors in calf
caudate membranes (mainly constituting the homolo-
gous bovine 5-HT1B receptor) was more than 10 times
less than that for the rat r5-HT1B receptor. (R)-25 had
very low affinities for all other receptors examined,
including 5-HT2A, 5-HT2C, 5-HT6, and 5-HT7, R1-, R2-,
and â-adrenoceptors, and dopamine D1 and D2 (Table
2).
The r5-HT1B antagonistic property of (R)-25 was
characterized in the K+-stimulated release of [3H]-5-HT
from preloaded rat occipital cortical slices. As shown
in Table 3 (R)-25 dose-dependently potentiated the [3H]-
5-HT release in the concentration range 10-1000 nM.
Furthermore, the potentiation of the release caused by
(R)-25 was antagonized at 1000 nM but not at 100 nM
of unlabeled 5-HT into the superfusion fluid (Table 4),
which indicates competition between these two com-
pounds.
P h a r m a cology
Radioligand binding studies, using [125I]iodocyanopin-
dolol as ligand for the r5-HT1B receptor, showed that
compound (R)-25 had the highest affinity for this
receptor (Table 1). The other enantiomer, (S)-25, and
(R,S)-27 and (R,S)-30 were 4-5 times less active as (R)-
25. The other compounds tested ((R,S)-26, (R,S)-28, and
(R,S)-29) were even less potent. (R)-25 was therefore
chosen for further studies in order to elucidate its
selectivity and its in vivo properties.
The effect of (R)-25 on the 5-HT turnover in rat brain
in vivo was determined by using the 5-HTP accumula-
tion technique. At 20 mg/kg sc (R)-25, the 5-HTP

A New Selective Rat 5-HT1B Receptor Antagonist
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 11 1937
Ta ble 4. Antagonism of the (R)-25-Induced Potentiation of K+-Stimulated [3H]-5-HT Release from Brain Slices by 5-HT
S2/S1
% of control
expt
1
treatment
control
(R)-25
5-HT
(R)-25 + 5-HT
control
(R)-25
5-HT
concn, nM
n
(mean ( SEM)
(mean ( SEM)
4
4
6
5
4
4
6
6
0.86 ( 0.04
1.28 ( 0.03
0.71 ( 0.02
1.39 ( 0.07
0.75 ( 0.02
1.12 ( 0.03
0.60 ( 0.02
0.80 ( 0.02
1000
100
1000 + 100
149 ( 3
83 ( 2
161 ( 8
2
1000
1000
1000 + 1000
149 (4
80 ( 3
(R)-25 + 5-HT
107 ( 3a
a
P < 0.05 vs (R)-25 and 5-HT (Dunnett’s t-test following ANOVA).
Ta ble 5. Effect of (R)-25, 20 mg/kg sc, on the 5-HT Turnover in Four Rat Brain Regions
5-HTP, nmol/g
of tissue
5-HT, nmol/g
of tissue
5-HIAA, nmol/g
of tissue
5-HTP, %
of control
5-HIAA/5-HT,
% of control
region
treatment
hypothalamus
saline
(R)-25
saline
(R)-25
saline
(R)-25
saline
(R)-25
1.21 ( 0.06
1.69 ( 0.07
0.47 ( 0.03
0.67 ( 0.02
0.37 ( 0.02
0.53 ( 0.02
0.43 ( 0.03
0.62 ( 0.02
5.05 ( 0.27
4.36 ( 0.17
1.79 ( 0.13
1.68 ( 0.07
2.77 ( 0.11
2.42 ( 0.11
2.01 ( 0.13
1.87 ( 0.09
2.73 ( 0.12
3.91 ( 0.11
1.64 ( 0.09
2.30 ( 0.07
1.05 ( 0.07
1.47 ( 0.07
2.43 ( 0.18
3.27 ( 0.12
140 ( 5a
148 ( 3a
142 ( 5a
142 ( 5a
166 ( 6a
142 ( 5a
161 ( 10a
145 ( 5a
hippocampus
frontal cortex
striatum
a
P < 0.05 vs control (Dunnett’s t-test following ANOVA). (R)-25 or saline was injected 30 min before 3-hydroxybenzylhydrazine
dihydrochloride, 100 mg/kg sc, and the rats were sacrificed 30 min thereafter. The brain regions were rapidly dissected, frozen on dry ice,
and analyzed with HPLC technique.
affinity for the 5-HT1D receptor.24 The affinity of (R)-
Ta ble 6. Effect of (R)-25 on the Wet Dog Shake Response
(WDS) in Rats
25 for the latter receptor type remains to be elucidated.
dose,
mg/kg sc
no. of WDS/60 minb
(mean ( SEM)
The potentiation of the K+-stimulated [3H]-5-HT
release from superfused slices of rat occipital cortex and
the competition between (R)-25 and 5-HT in this in vitro
model showed that (R)-25 is an antagonist at this
receptor. Moreover, (R)-25 markedly increased the
5-HTP accumulation in all four brain regions examined
in 3-hydroxybenzylhydrazine-treated rats and increased
the 5-HIAA/5-HT ratio in the brain even more. These
findings suggest that the 5-HT turnover was increased
in these 5-HT terminal regions, supposedly due to the
increased 5-HT release from the terminals. The induc-
tion of wet dog shake behavior by (R)-25 is in strong
accordance with this notion since the response was
abolished by depletion of 5-HT in the brain with pCPA.
These observations indicate that, under normal condi-
tions, the terminal 5-HT1B receptors have a functional
role in determining the amount of 5-HT released from
the terminals.
pretreatmenta
compd
saline
(R)-25
(R)-25
quipazine
quipazine
n
30
10
9
8
8
6.0 ( 0.2
17 ( 1.6c
9.2 ( 0.8
36 ( 3.0
30 ( 3.0
saline
pCPA
saline
pCPA
3
3
1
1
a
pCPA, 200 mg/kg ip, or saline was injected 72 and 48 h before
b
the test compound. The number of WDS was counted from 5 to
65 min after the injection of the test compounds. c P < 0.05 vs
saline control and pCPA + (R)-25 (Dunnett’s t-test following
ANOVA).
accumulation was significantly increased (40%) com-
pared with saline-treated controls in all four brain
regions analyzed (Table 5). The ratio 5-HIAA/5-HT in
these brain regions was even more elevated (40-60%).
An enhanced release of 5-HT leading to increased
synaptic concentration of 5-HT was strongly supported
by the observation that (R)-25 induced wet dog shake
behavior in rats (Table 6). The effect was abolished by
pretreatment of the rats with the tryptophan hydroxy-
lase inhibitor p-chlorophenylalanine (pCPA), indicating
the presynaptic 5-HT origin of the effect. When the wet
dog shake behavior was evoked by the 5-HT2A/5-HT2C
receptor agonist quipazine, there was no significant
reduction by the pCPA treatment (Table 6).
Since (R)-25 is a selective r5-HT1B receptor antago-
nist, this compound may become a valuable tool for
studies of the functional role of the r5-HT1B receptors
in rodents.
Exp er im en ta l Section
Ch em istr y. 1H and 13C NMR spectra were measured on a
Varian Gemini-300 (300 MHz), Varian Unity-400 (400 MHz),
or J EOL FX200 (200 MHz) spectrometer using Me4Si as an
internal standard. Mass spectra were recorded on a Finnigan
UNICAM Automass or Finnigan MAT SSQ 710 instrument.
Melting points were determined on a Mettler FP61 or FP62
instrument and are not corrected. Elemental analyses were
within (0.4% of theoretical values unless otherwise stated.
Thin-layer chromatography was performed on silica gel plates
(Merck No. 1.05719) with fluorescent indicator, and the plates
were visualized with light at 254 and 365 nm. Column
chromatography was performed on silica gel (Merck 60, 230-
400 mesh ASTM). Tetrahydrofuran was distilled from sodium/
benzophenone. Diethyl ether was dried over sodium, and
methanol, N,N-dimethylformamide, and dioxane were dried
over 3-Å molecular sieves.
Discu ssion
The receptor profile of (R)-25 shows that this com-
pound is a selective r5-HT1B receptor ligand with
moderate to high potency. Since (R)-25 has low affinity
for the 5-HT1D receptor in calf caudate, which mainly
appears to consist of the bovine 5-HT1B receptor,22,23 the
receptor profile of (R)-25 differs from that of 2′-methyl-
4′-(5-methyl[1,2,4]oxadiazol-3-yl)biphenyl-4-carboxylic
acid [4-methoxy-3-(4-methylpiperazin-1-yl)phenyl]amide
(GR127,935) which has high affinity for the two ho-
mologous forms of the 5-HT1B receptor and also has high

1938 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 11
Berg et al.
2-(Hydr oxym eth ylen e)-5-m eth oxy-3,4-dih ydr o-2H-n aph -
th a len -1-on e (3). To a suspension of sodium methoxide
(prepared from sodium (5.7 g, 0.25 mol) and anhydrous
methanol and the excess of methanol removed in vacuo) in
anhydrous benzene (80 mL) was added a solution of ethyl
formate (20 mL, 0.26 mol), dissolved in anhydrous benzene
(120 mL). The mixture was stirred at 0 °C, and 5-methoxy-
1-tetralone (24.8 g, 0.14 mol), dissolved in anhydrous benzene
(120 mL), was added dropwise over a period of 2 h. After
stirring at 0 °C for an additional 2 h, the reaction mixture
was stirred at ambient temperature for 15 h. Water (50 mL)
was added carefully, and the phases were separated. The
organic phase was extracted with a 2 M aqueous solution of
sodium hydroxide, and the combined water phases were cooled
on an ice bath and acidified with a 2 M aqueous solution of
hydrochloric acid. The acidified water phase was extracted,
twice, with methylene chloride, and the combined organic
phases were dried (Na2SO4), filtered, and evaporated in vacuo
to afford 24.8 g (86% yield) of a brown oil that crystallized on
removed using a Dean-Stark trap. The solution was cooled
and washed with
a saturated aqueous sodium hydrogen
carbonate solution and water. The organic phase was dried
(Na2SO4), filtered, and evaporated in vacuo. Purification on
a silica gel column using hexane/ethyl acetate, 3:1, as the
eluent gave 2.3 g (62% yield) of the title compound as colorless
crystals: mp 43-44 °C; 1H NMR (200 MHz, CDCl3) δ 7.18 (app
t, J ) 8 Hz, 1 H), 7.11 (t, J ) 2 Hz, 1 H), 6.87 (d, J ) 8 Hz, 1
H), 6.75 (d, J ) 8 Hz, 1 H), 3.83 (s, 3 H), 2.87 (t, J ) 9 Hz, 2
H), 2.48 (br t, J ) 8 Hz, 2 H); 13C NMR (50 MHz, CDCl3) δ
156.2, 141.6, 132.0, 127.4, 123.2, 120.6, 119.4, 112.7, 109.8,
55.6, 24.2, 19.1; EIMS (70 eV) m/z (relative intensity) 185 (M+,
100), 170 (48), 154 (44), 145 (25), 129 (20), 115 (41). Anal.
(C12H11NO) C, H, N.
6-Cya n o-7,8-d ih yd r o-1-n a p h th ol (1). A solution of boron
tribromide (7.7 g, 31 mmol) in methylene chloride (30 mL) was
added to a solution of 2-cyano-5-methoxy-3,4-dihydronaphtha-
lene (1.9 g, 10 mmol) in methylene chloride (30 mL) at -50
°C. The reaction solution was allowed to reach room temper-
ature and stirring was continued for 1.5 h. The reaction was
quenched with ice-water, the phases were separated, and the
organic phase was dried (Na2SO4), filtered, and evaporated in
vacuo. Purification on a silica gel column using hexane/ethyl
acetate as an eluent gave 1.5 g (85% yield) of the title
1
standing: mp 68-69 °C (lit.25 mp 68-69 °C); H NMR (300
MHz, CDCl3) δ 8.21 (br s, 1 H), 7.60 (d, J ) 8 Hz, 1 H), 7.30
(t, J ) 8 Hz, 1 H), 7.02 (d, J ) 8 Hz, 1 H), 3.86 (s, 3 H), 2.88
(t, J ) 7 Hz, 2 H), 2.53 (t, J ) 7 Hz, 2 H); 13C NMR (50 MHz,
CDCl3) δ 182.6, 176.7, 156.3, 132.7, 130.3, 127.3, 118.3, 114.5,
108.5, 55.8, 22.3, 21.1; EIMS (70 eV) m/z (relative intensity)
204 (M+, 100), 187 (47), 175 (41), 160 (29), 131 (23), 115 (38),
77 (39). Anal. (C12H12O3) C, H, N.
2-Cya n o-5-m e t h oxy-3,4-d ih yd r o-2H -n a p h t h a le n -1-
on e (4). To a solution of 2-(hydroxymethylene)-5-methoxy-
3,4-dihydro-2H-naphthalen-1-one (24.3 g, 0.12 mol) in glacial
acetic acid (480 mL) was added hydroxylamine hydrochloride
(16.5 g, 0.24 mol), and the reaction mixture was heated at
reflux for 30 min. The acetic acid was evaporated in vacuo,
and the residue was dissolved in water (300 mL) and extracted,
twice, with diethyl ether. The phases were separated, and the
1
compound as white crystals: mp 162-164 °C; H NMR (300
MHz, CDCl3) δ 7.16 (t, J ) 2 Hz, 1 H), 7.10 (t, J ) 8 Hz, 1 H),
6.81 (dd, J ) 8, 1 Hz, 1 H), 6.76 (d, J ) 7 Hz, 1 H), 5.29 (s, 1
H), 2.89 (t, J ) 9 Hz, 2 H), 2.55 (app dt, J ) 9, 2 Hz, 2 H); 13
C
NMR (75 MHz, CDCl3) δ 152.6, 141.9, 132.5, 127.5, 121.1,
121.0, 119.7, 117.9, 109.5, 24.0, 19.0; EIMS (70 eV) m/z
(relative intensity) 171 (M+, 100), 170 (77), 156 (22), 142 (20),
131 (47), 115 (33). Anal. (C11H9NO) C, H, N.
3-Cya n o-8-h yd r oxy-2H -ch r om en e (7). A solution of
8-methoxy-3-cyano-2H-chromene (6.4 g, 34 mmol) in methyl-
ene chloride (150 mL) was cooled to -20 °C, and a solution of
boron tribromide (9.9 mL, 103 mmol) in methylene chloride
(100 mL) was added dropwise. After the addition, the reaction
mixture was stirred at -20 °C for another 17 h. The reaction
was quenched by the careful addition of water during 20 min.
The phases were separated, and the organic phase was dried
(Na2SO4), filtered, and evaporated in vacuo to give a crude
product. Purification on a silica gel column using hexane/ethyl
acetate (3:1) as the eluent gave 5.4 g (92% yield) as white
combined organic phases were washed with
a saturated
aqueous sodium hydrogen carbonate solution and then with
water. The ether phase was dried (Na2SO4), filtered, and
evaporated in vacuo to afford 27 g of crude isoxazole (MS (CI)
m/z (relative intensity) 202 (100, M + 1)).
To an ice-cold solution of the crude isoxazole in diethyl ether
(400 mL) was added dropwise a solution of sodium methoxide
(prepared from sodium; 5.5 g, 0.24 mol) in anhydrous methanol
(125 mL) over a period of 45 min. The reaction mixture was
stirred at 0 °C for 2 h, and water (250 mL) was then added
carefully. The phases were separated, and the water phase
was extracted with methylene chloride. The phases were
separated, and the organic phase was dried (Na2SO4), filtered,
and evaporated in vacuo to afford 19 g (79% yield) of the title
compound as light-brown crystals: mp 126-128 °C (lit.26 mp
1
crystals: mp 120-121 °C; H NMR (300 MHz, CDCl3) δ 7.20
(t, J ) 1 Hz, 1 H), 6.96 (dd, J ) 8, 2 Hz, 1 H), 6.89 (t, J ) 8
Hz, 1 H), 6.70 (dd, J ) 7, 2 Hz, 1 H), 5.43 (br s, 1 H), 4.87 (dd,
J ) 1 Hz, 2 H); 13C NMR (75 MHz, CDCl3) δ 144.3, 140.7,
138.9, 122.7, 120.2, 119.9, 119.2, 116.3, 103.4, 64.7; EIMS (70
eV) m/z (relative intensity) 173 (M+, 100), 145 (54), 130 (25),
117 (63), 89 (53), 63 (33). Anal. (C10H7NO2) C, H, N.
1
130-132 °C); H NMR (300 MHz, CDCl3) δ 7.67 (dd, J ) 8, 1
Hz, 1 H), 7.33 (t, J ) 8 Hz, 1 H), 7.09 (dd, J ) 8, 1 Hz, 1 H),
3.88 (s, 3 H), 3.73 (dd, J ) 12, 4 Hz, 1 H), 3.21 (app dt, J ) 18,
4 Hz, 1 H), 2.90-2.77 (m, 1 H), 2.58 (dq, J ) 13, 4 Hz, 1 H),
2.47-2.32 (m, 1 H); 13C NMR (50 MHz, CDCl3) δ 188.3, 156.8,
132.1, 131.4, 127.7, 119.6, 116.9, 115.5, 55.9, 40.6, 27.0, 21.6;
EIMS (70 eV) m/z (relative intensity) 201 (M+, 100), 148 (93),
120 (70), 105 (21), 90 (57), 77 (51). Anal. (C12H11NO2) C, H,
N.
2-Cya n o-5-m eth oxy-3,4-d ih yd r on a p h th a len e (5). To an
ice-cold solution of 2-cyano-5-methoxy-1-tetralone (4 g, 20
mmol) in anhydrous methanol (150 mL) was added sodium
borohydride (3.6 g, 95 mmol) portionwise. The reaction
mixture was stirred at ambient temperature for 35 min, and
the reaction was then quenched by the addition of a 1 M
aqueous solution of hydrochloric acid (25 mL). The methanol
was evaporated in vacuo, and the remaining suspension was
diluted with water (50 mL) and extracted, twice, with meth-
ylene chloride. The combined organic phases were dried (Na2-
SO4), filtered, and evaporated in vacuo affording 3.9 g of a
brown solid.
8-Meth oxy-3-(m or p h olin oca r bon yl)-2H-ch r om en e (9).
To a suspension of 8-methoxy-2H-chromene-3-carboxylic acid
(3.0 g, 15 mmol) in toluene (40 mL) was added thionyl chloride
(1.1 mL, 15 mmol), and the reaction mixture was heated at
reflux for 3 h. The clear solution was evaporated in vacuo,
and the residue was dissolved in anhydrous dioxane (40 mL)
and cooled on an ice bath. To the ice-cooled solution of the
acid chloride was added morpholine (3.2 g, 36 mmol), dissolved
in anhydrous dioxane (20 mL), dropwise, and the reaction
mixture was allowed to stir at room temperature for 40 min.
The solvent was evaporated in vacuo, and the crude product
was partitioned between methylene chloride and water. The
phases were separated, and the organic phase was dried (Na2-
SO4), filtered, and evaporated in vacuo to give a crude product.
Purification on a silica gel column using ethyl acetate as the
eluent gave 3.1 g (77% yield) of the title compound as light-
1
yellow crystals: mp 96-97 °C; H NMR (400 MHz, CDCl3) δ
6.91-6.84 (m, 2 H), 6.72 (dd, J ) 7, 2 Hz, 1 H), 6.60 (t, J ) 2
Hz, 1 H), 4.94 (d, J ) 2 Hz, 2 H), 3.88 (s, 3 H), 3.70 (br s, 8 H);
13C NMR (75 MHz, CDCl3, 50 °C) δ 167.5, 148.3, 143.5, 127.1,
126.9, 122.2, 122.1, 120.3, 114.0, 67.0, 66.3, 56.4, 45.3; EIMS
(70 eV) m/z (relative intensity) 275 (M+, 60), 189 (100), 161
(54), 118 (41), 114 (9), 86 (27). Anal. (C15H17NO4) C, H, N.
The residue was dissolved in toluene (100 mL), and a
catalytic amount of p-toluenesulfonic acid was added. The
reaction was refluxed for 10 h, and water was continuously

A New Selective Rat 5-HT1B Receptor Antagonist
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 11 1939
8-Hyd r oxy-3-(m or p h olin oca r bon yl)-2H-ch r om en e (10).
The compound was prepared as described for 1 starting from
9 (17 g, 63 mmol). Purification on a silica gel column using
chloroform/ethanol (100:0.5) as the eluent gave 6.7 g (41%
yield) of the title compound as colorless crystals: mp 170-
compound as a colorless oil. An analytical sample was purified
on a silica gel column using hexane/ethyl acetate (3:1) as the
eluent: [R]21 +41° (c 1.4, methanol); 1H NMR (300 MHz,
D
CDCl3) δ 7.37-7.25 (m, 10 H), 4.71 (d, J ) 15 Hz, 1 H), 4.51
(d, J ) 15 Hz, 1 H), 4.52 (s, 2 H), 4.41 (d, J ) 17 Hz, 1 H), 4.26
(d, J ) 17 Hz, 1 H), 3.96-3.88 (m, 1 H), 3.55 (dd, J ) 16, 5
Hz, 1 H), 3.46 (dd, J ) 10, 5 Hz, 1 H), 3.29 (app t, J ) 11 Hz,
1 H), 3.12 (dd, J ) 12, 3 Hz, 1 H); 13C NMR (75 MHz, CDCl3)
δ 166.7, 137.5, 136.1, 128.8, 128.5, 128.3, 127.9, 127.8, 127.8,
73.6, 72.5, 69.8, 67.7, 49.5, 47.5; EIMS (70 eV) m/z (relative
intensity) 311 (M+, 8), 220 (11), 190 (17), 146 (10), 91 (100),
65 (37). Anal. (C19H21NO3) C, H, N.
1
172 °C; H NMR (400 MHz, CDCl3) δ 6.88 (dd, J ) 8, 2 Hz, 1
H), 6. 83 (app t, J ) 8 Hz, 1 H), 6.65 (dd, J ) 8, 2 Hz, 1 H),
6.59 (t, J ) 2 Hz, 1 H), 5.52 (br s, 1 H), 4.94 (d, J ) 2 Hz, 2 H),
3.70 (br s, 8 H); 13C NMR (50 MHz, CDCl3, 50 °C) δ 167.5,
144.6, 141.0, 126.7, 126.5, 122.2, 121.5, 119.4, 117.3, 67.1, 66.5,
45.4; EIMS (70 eV) m/z (relative intensity) 261 (M+, 98), 175
(100), 147 (60), 91 (90), 86 (47). Anal. (C14H15NO4) C, H, N.
(S)-(-)-4-N-Ben zyl-6-[(b en zyloxy)m et h yl]-2,3,5,6-t et -
r a h yd r o-1,4-oxa zin -3-on e ((S)-15). The compound was
prepared as described for its antipode (R)-15. The spectro-
scopic data were in full accordance with its enantiomer: yield
8-Hyd r oxy-3-(m or p h olin om et h yl)-2H -ch r om en e (11).
To a suspension of lithium aluminum hydride (0.63 g, 16
mmol) in anhydrous tetrahydrofuran (350 mL) was carefully
added anhydrous aluminum chloride (0.73 g, 5.5 mmol)
portionwise. After stirring for 1 h at ambient temperature,
the suspension was filtered through Celite, and the clear
solution was cooled on an ice bath. To the cooled solution of
aluminum hydride was added 8-hydroxy-3-(morpholinocarbon-
yl)-2H-chromene (2.3 g, 8.8 mmol), and the reaction mixture
was stirred on an ice bath for 20 min. The reaction was
quenched by the careful addition of a mixture of water and
tetrahydrofuran (1:1) and was then poured into methylene
chloride (300 mL). The crystals were filtered and dried in
vacuo to afford 2.1 g (96% yield) of the title compound as white
crystals. An analytical sample was crystallized from ethyl
93%; [R]21 -38° (c 1.0, methanol). Anal. (C19H21NO3) C, H,
D
N.
(R)-(-)-4-(Ben zylam in o)-2-[(ben zyloxy)m eth yl]m or ph o-
lin e ((R)-16). To a stirred solution of (R)-15 (39 g, 0.12 mol)
in anhydrous diethyl ether (850 mL) was added portionwise
lithium aluminum hydride (9.4 g, 0.25 mmol). After stirring
at room temperature for 40 min, the reaction was quenched
by the addition of water (9.4 mL) followed by a 15% aqueous
solution of sodium hydroxide (9.4 mL) and again water (28
mL). After stirring for 20 min, the reaction mixture was
filtered, dried (Na2SO4), filtered, and evaporated in vacuo to
give 36 g (97% yield) of the title compound as a colorless oil.
An analytical sample was purified on a silica gel column using
1
acetate which gave white needles: mp 149-150 °C; H NMR
(400 MHz, CDCl3) δ 6.79-6.74 (m, 2 H), 6.55 (dd, J ) 7, 3 Hz,
1 H), 6.33 (app t, J ) 2 Hz, 1 H), 5.43 (s, 1 H), 4.82-4.81 (m,
2 H), 3.70 (app t, J ) 4 Hz, 4 H), 3.05 (br s, 2 H), 2.43 (app t,
J ) 4 Hz, 4 H); 13C NMR (75 MHz, CDCl3) δ 144.5, 140.2,
131.7, 122.9, 122.7, 121.9, 118.2, 115.7, 68.1, 67.2, 62.3, 53.8;
EIMS (70 eV) m/z (relative intensity) 247 (M+, 13), 161 (36),
160 (100), 132 (9.4), 115 (7), 100 (16). Anal. (C14H17NO3), C,
H, N.
hexane/ethyl acetate (3:1) as the eluent: [R]21 -14° (c 1.5,
D
methanol); 1H NMR (300 MHz, CDCl3) δ 7.35-7.21 (m, 10 H),
4.56 (d, J ) 12 Hz, 1 H), 4.50 (d, J ) 12 Hz, 1 H), 3.91-3.83
(m, 1 H), 3.82-3.73 (m, 1 H), 3.70 (dt, J ) 11, 2 Hz, 1 H), 3.48
(s, 2 H), 3.47 (dd, J ) 10, 6 Hz, 1 H), 3.39 (dd, J ) 10, 4 Hz,
1 H), 2.76-2.61 (m, 2 H), 2.17 (dt, J ) 11, 3 Hz, 1 H), 1.96
(app t, J ) 11 Hz, 1 H); 13C NMR (75 MHz, CDCl3) δ 138.1,
137.7, 129.2, 128.4, 128.3, 127.7, 127.6, 127.1, 74.8, 73.3, 71.4,
66.7, 63.2, 55.3, 52.9; EIMS (70 eV) m/z (relative intensity)
297 (M+, 0.3), 206 (100), 191 (99), 190 (69), 146 (100), 120 (43),
100 (82), 91 (99), 65 (99). Anal. (C19H23NO2) C, H, N.
(R)-(+)-1-(N-Ben zyla m in o)-3-(b en zyloxy)p r op a n -2-ol
((R)-14). To benzylamine (300 mL, 2.8 mol) was added benzyl
(S)-glycidyl ether (70 g, 0.43 mol), and the reaction mixture
was stirred for 65 h at room temperature. The excess
benzylamine was removed in vacuo, and the crude yellow oil
was purified by distillation to give 92 g (80% yield) of the title
(S)-(+)-4-(Ben zylam in o)-2-[(ben zyloxy)m eth yl]m or ph o-
lin e ((S)-16). The compound was prepared as described for
its antipode (R)-16. The spectroscopic data were in full
accordance with its enantiomer: yield 98%; [R]21D +17° (c 1.5,
methanol). Anal. (C19H23NO2) C, H, N.
compound as a viscous oil: bp 176-178 °C (0.01 mmHg); [R]21
D
1
+12° (c 1.4, methanol); H NMR (300 MHz, CDCl3) δ 7.40-
7.18 (m, 10 H), 4.54 (s, 2 H), 3.95-3.70 (m, 3 H), 3.55-3.40
(m, 2 H), 2.80-2.60 (m, 4 H); 13C NMR (75 MHz, CDCl3) δ
140.5, 138.3, 128.9, 128.6, 128.2, 127.5, 73.7, 73.1, 69.2, 54.0,
51.6; EIMS (70 eV) m/z (relative intensity) 271 (M+, 0.4), 180
(21), 150 (8), 120 (100), 106 (72), 91 (99), 65 (70). Anal.
(C17H21NO2) C, H, N.
(R)-(-)-2-(Hyd r oxym eth yl)m or p h olin e ((R)-17). A solu-
tion of (R)-16 (86 g, 0.29 mol) in ethanol (800 mL) was acidified
by the dropwise addition of concentrated hydrochloric acid (30
mL). Palladium (10%) on activated carbon (6 g) was added,
and the mixture was hydrogenated at 55-60 °C and atmo-
spheric pressure for 4 h. The catalyst was filtered off, and
the solvent was evaporated in vacuo. The remaining solid was
dissolved in water (75 mL) and cooled with an ice bath. The
solution was alkalized with a 40% aqueous solution of sodium
hydroxide, and the solvent was evaporated in vacuo. The
remaining solid was dissolved in methylene chloride, filtered,
and evaporated in vacuo which gave 17 g (52% yield) of the
title compound as a colorless oil. An analytical sample was
purified by distillation: bp 78-80 °C (0.6 mmHg); [R]21D -2.6°
(c 2, methanol); 1H NMR (300 MHz, CDCl3) δ 4.30-3.85 (m, 1
H), 3.68-3.51 (m, 4 H), 2.92-2.80 (m, 3 H), 2.71-2.46 (m, 3
H); 13C NMR (75 MHz, CDCl3) δ 77.0, 67.5, 63.5, 47.2, 45.4;
EIMS (70 eV) m/z (relative intensity) 117 (M+, 9), 99 (37), 86
(52), 71 (52), 57 (99), 56 (100). Anal. (C5H11NO2) C, H, N.
(S)-(-)-1-(N-Ben zyla m in o)-3-(b en zyloxy)p r op a n -2-ol
((S)-14). The compound was prepared as described for its
antipode (R)-14. The spectroscopic data were in full ac-
cordance with its enantiomer: yield 70%; [R]21 -12° (c 1.1,
D
methanol). Anal. (C17H21NO2) C, H, N.
(R)-(+)-4-N-Ben zyl-6-[(b en zyloxy)m et h yl]-2,3,5,6-t et -
r a h yd r o-1,4-oxa zin -3-on e ((R)-15). To an ice-cooled solution
of (R)-14 (91 g, 0.34 mol) and triethylamine (51 mL, 0.37 mol)
in methylene chloride (1000 mL) was added dropwise a
solution of chloroacetyl chloride (38 g, 0.34 mol) in methylene
chloride (200 mL). After the addition, the reaction mixture
was stirred at ambient temperature for 2.5 h. The reaction
mixture was washed with a 1 M aqueous solution of hydro-
chloric acid. The organic phase was dried (Na2SO4), filtered,
and evaporated in vacuo which gave 116 g of a crude solid
residue: CIMS m/z 348 (M + 1).
The residue, dissolved in methanol (300 mL), was added to
a solution of sodium (8.3 g, 0.36 mol) in methanol (1500 mL),
and the reaction mixture was stirred at reflux for 4 h. The
solvent was evaporated in vacuo, and the residue was parti-
tioned between diethyl ether and a 1 M aqueous solution of
hydrochloric acid. The phases were separated, and the ether
phase was washed with water, dried (Na2SO4), filtered, and
evaporated in vacuo to give 94 g (90% yield) of the title
(S)-(-)-2-(Hydr oxym eth yl)m or ph olin e ((S)-17). The com-
pound was prepared as described for its antipode (R)-17. The
spectroscopic data were in full accordance with its enanti-
omer: yield 22%; [R]21D +1.7° (c 1.1, methanol). Anal. (C5H11
NO2) C, H, N.
-
(R)-(+)-2-(H yd r oxym et h yl)-4-(t r ip h en ylm et h yl)m or -
p h olin e ((R)-18). To an ice-cooled solution of (R)-17 (9.5 g,
81 mmol) and triethylamine (14 mL, 98 mmol) in methylene
chloride (100 mL) was added dropwise a solution of triphenyl-
methyl chloride (23 g, 81 mmol). After the addition, the

1940 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 11
Berg et al.
reaction mixture was stirred at ambient temperature for 2 h.
The reaction mixture was washed with water, the phases were
separated, and the organic phase was dried (Na2SO4), filtered,
and evaporated in vacuo to give the crude product. Purifica-
tion on a silica gel column using chloroform as the eluent gave
solvent evaporated in vacuo. The remaining solid was dis-
solved in water (100 mL) and cooled with an ice bath. The
solution was alkalized with an aqueous solution of 2 M sodium
hydroxide and extracted with methylene chloride. The phases
were separated, and the organic phase was dried (Na2SO4),
filtered, and evaporated in vacuo. Purification on a silica gel
column using chloroform/ethanol saturated with NH3 (100:4)
as the eluent gave 1.7 g (57% yield) of the title compound as
a viscous colorless oil: 1H NMR (300 MHz, CDCl3) δ 7.79 (d,
J ) 8 Hz, 2 H), 7.35 (d, J ) 8 Hz, 2 H), 4.02-3.92 (m, 2 H),
3.80 (app dt, J ) 12, 2 Hz, 1 H), 3.70-3.62 (m, 1 H), 3.53 (ddd,
J ) 11, 9, 5 Hz, 1 H), 2.86 (dd, J ) 12, 2 Hz, 1 H), 2.81-2.76
(m, 2 H), 2.57 (dd, J ) 12, 10 Hz, 1 H), 2.44 (s, 3 H), 5.00 (s,
1 H); 13C NMR (75 MHz, CDCl3) δ 144.9, 132.7, 129.8, 127.9,
73.6, 70.1, 67.5, 47.2, 45.2, 21.4; EIMS (70 eV) m/z (relative
intensity) 271 (M+, 1), 155 (4), 99 (64), 91 (26), 71 (63), 56 (100).
Anal. (C12H17NO4S) C, H, N.
17 g (58% yield) of the title compound as a viscous oil: [R]21
D
+17° (c 2, methanol); 1H NMR (300 MHz, CDCl3) δ 7.47 (br d,
J ) 7 Hz, 6 H), 7.26 (t, J ) 7 Hz, 6 H), 7.15 (t, J ) 7 Hz, 3 H),
4.00-3.80 (m, 3 H), 3.56-3.36 (m, 2 H), 2.91 (t, J ) 9 Hz, 2
H), 2.03 (br s, 1 H), 1.69 (app t, J ) 10 Hz, 1 H), 1.47 (t, J )
11 Hz, 1 H); 13C NMR (75 MHz, CDCl3) δ 129.4, 127.7, 126.2,
76.9, 76.8, 67.1, 64.2, 49.6, 48.1; EIMS (70 eV) m/z (relative
intensity) 359 (M+, 1), 244 (27), 243 (100), 165 (58). Anal.
(C24H25NO2) C, H, N.
(S)-(-)-2-(H yd r oxym et h yl)-4-(t r ip h en ylm et h yl)m or -
p h olin e ((S)-18). The compound was prepared as described
for its antipode (R)-18. The spectroscopic data were in full
accordance with its enantiomer: yield 36%; [R]21D -16° (c 1.1,
methanol). Anal. (C24H25NO2) C, H, N.
(R,S)-4-Met h yl-2-[[(p -t olylsu lfon yl)oxy]m et h yl]m or -
p h olin e (22). To a solution of 24 (0.75 g, 2.8 mmol) and
potassium carbonate (0.57 g, 4.1 mmol) in anhydrous N,N-
dimethylformamide (35 mL) was added a solution of io-
domethane (170 mL, 2.8 mmol) in anhydrous N,N-dimethyl-
formamide (5 mL) dropwise during 30 min. After the addition,
the reaction mixture was stirred for another 30 min and
filtered, and the solvent was evaporated in vacuo. Purification
on a silica gel column using chloroform/ethanol saturated with
NH3 (100:2) as the eluent gave 0.56 g (71% yield) of the title
compound as a viscous colorless oil: 1H NMR (300 MHz,
CDCl3) δ 7.79 (d, J ) 8 Hz, 2 H), 7.75 (d, J ) 8 Hz, 2 H), 4.03
(dd, J ) 10, 6 Hz, 1 H), 3.97 (dd, J ) 10, 5 Hz, 1 H), 3.82 (ddd,
J ) 11, 3, 2 Hz, 1 H), 3.72 (m, 1 H), 3.59 (dt, J ) 11, 3 Hz, 1
H), 2.68 (app dt, J ) 11, 2 Hz, 1 H), 2.58 (app dq, J ) 12, 4,
2 Hz, 1 H), 2.45 (s, 3 H), 2.26 (s, 3 H), 2.08 (dt, J ) 11, 3 Hz,
1 H), 1.86 (dd, J ) 11, 10 Hz, 1 H); 13C NMR (75 MHz, CDCl3)
δ 145.0, 132.8, 129.9, 128.0, 72.3, 70.2, 66.5, 56.3, 54.4, 46.1,
21.5; EIMS (70 eV) m/z (relative intensity) 285 (M+, 8), 228
(R)-(+)-2-[[(p-Tolylsu lfon yl)oxy]m eth yl]-4-(tr ip h en yl-
m eth yl)m or p h olin e ((R)-12). To a cooled (-10 °C) solution
of (R)-18 (17 g, 47 mmol) and pyridine (4.2 mL, 51 mmol) in
methylene chloride (60 mL) was added portionwise p-tolylsul-
fonyl chloride (9.8 g, 51 mmol). After the addition, the reaction
mixture was stirred at ambient temperature for 17 h. The
product precipitated, and the crystals were filtered and washed
with cold methylene chloride. Purification on a silica gel
column using chloroform as the eluent gave 17 g (70% yield)
of the title compound as white crystals: mp 211-212 °C; [R]21
D
1
+20° (c 0.5, methanol); H NMR (300 MHz, CDCl3) δ 7.70 (d,
J ) 8 Hz, 2 H), 7.40 (br app d, J ) 7 Hz, 6 H), 7.30-7.22 (m,
8 H), 7.17 (t, J ) 7 Hz, 3 H), 4.07-3.73 (m, 5 H), 2.85 (app t,
J ) 12 Hz, 2 H), 2.43 (s, 3 H), 1.70-1.25 (m, 2 H); 13C NMR
(75 MHz, CDCl3) δ 144.8, 132.9, 129.8, 129.4, 128.0, 127.7,
126.4, 78.0, 73.5, 70.3, 67.0, 49.8, 47.8, 21.5; EIMS (70 eV) m/z
(relative intensity) 513 (M+, 0.1), 244 (20), 243 (100), 241 (13),
166 (12), 165 (51), 99 (13), 91 (11), 56 (11). Anal. (C31H31
NO4S) C, H, N.
-
(13), 155 (4), 130 (5), 114 (100), 91 (21), 71 (23). Anal. (C13H19
NO4S) C, H, N.
-
(S)-(-)-2-[[(p-Tolylsu lfon yl)oxy]m et h yl]-4-(t r ip h en yl-
m eth yl)m or p h olin e ((S)-12). The compound was prepared
as described for its antipode (R)-12. The spectroscopic data
(R)-(+)-2-[[[3-(Mor p h olin om et h yl)-2H -ch r om en -8-yl]-
oxy]m eth yl]m or p h olin e Meth a n esu lfon a te ((R)-25). To
a solution of 11 (1.7 g, 7 mmol) and (R)-12 (3.6 g, 7 mmol) in
dimethylformamide (60 mL) was added potassium carbonate
(1.5 g, 11 mmol), and the reaction mixture was stirred at 100
°C for 10 h. The reaction mixture was filtered and evaporated
in vacuo, and the crude product was partitioned between
methylene chloride and water. The phases were separated,
and the organic phase was dried (Na2SO4), filtered, and
evaporated in vacuo to give a crude product which was purified
on a silica gel column using hexane/ethyl acetate (3:1) as the
eluent. The residue was dissolved in acetic acid diluted to 30%
with water (100 mL in total), and the reaction mixture was
allowed to stir at ambient temperature for 20 min. The solvent
was evaporated in vacuo, the mixture was partitioned between
water and diethyl ether, the phases were separated, and the
water layer was cooled with an ice bath. After alkalization
with a 2 M aqueous solution of sodium hydroxide, the mixture
was extracted, twice, with methylene chloride. The combined
organic phases were dried (Na2SO4), filtered, and evaporated
in vacuo. Purification on a silica gel column using chloroform/
methanol/NH3 (95:5:1) as the eluent gave 1.1 g (46% yield) of
were in full accordance with its enantiomer: yield 46%; [R]21
D
-22° (c 0.11, methanol); mp 221-223 °C. Anal. (C31H31NO4S)
C, H, N.
(R,S)-3-(H yd r oxym et h yl)-1-(t r ip h en ylm et h yl)p ip er i-
d in e (21). The compound was prepared as described for (R)-
18 starting from (R,S)-3-(hydroxymethyl)piperidine: yield 95%
of a viscous oil; 1H NMR (400 MHz, DMSO, 100 °C) δ 7.40
(app d, J ) 8 Hz, 6 H), 7.27 (t, J ) 8 Hz, 6 H), 7.14 (t, J ) 8
Hz, 3 H), 3.98-3.95 (m, 1 H), 3.30-3.24 (m, 1 H), 3.19-3.13
(m, 1 H), 2.79 (br d, J ) 10 Hz, 1 H), 1.96-1.91 (m, 1 H), 1.79-
1.60 (m, 3 H), 1.42 (app dd, 1 H), 1.21 (t, J ) 10 Hz, 1 H),
0.82-0.78 (m, 1 H); 13C NMR (100 MHz, DMSO, 100 °C) δ
142.2, 128.4, 126.8, 125.2, 76.8, 63.9, 51.6, 48.7, 27.1, 24.5;
EIMS (70 eV) m/z (relative intensity) 357 (M+, 4), 280 (4), 244
(28), 243 (100), 165 (54), 91 (5). Anal. (C25H27NO) C, H, N.
(R,S)-3-[[(p -Tolylsu lfon yl)oxy]m et h yl]-1-(t r ip h en yl-
m eth yl)p ip er id in e (19). The compound was prepared as
described for (R)-12: yield 45% of white crystals; mp 209-
1
210 °C; H NMR (400 MHz, CDCl3) δ 7.68 (d, J ) 8 Hz, 2 H),
7.39 (br d, J ) 7 Hz, 6 H), 7.28-7.22 (m, 8 H), 7.14 (t, J ) 7
Hz, 3 H), 4.00-3.76 (m, 2 H), 3.00-2.54 (br signal, 2 H), 2.45
(s, 3 H), 2.27-2.15 (m, 1 H), 1.82-1.58 (m, 3 H), 1.48-1.07
(br signal, 1 H), 0.95-075 (br signal, 2 H); 13C NMR (100 MHz,
CDCl3) δ 144.5, 133.1, 129.7, 129.2, 127.8, 127.4, 126.0, 77.4,
72.9, 51.3, 49.0, 36.7, 27.3, 25.0, 21.6; EIMS (70 eV) m/z
(relative intensity) 511 (M+, 1), 434 (2), 244 (29), 243 (100),
165 (36), 91 (9). Anal. (C32H33NO3S) C, H, N.
the title compound as a colorless oil: [R]21 -1.3° (c 1.6,
D
1
methanol); H NMR (400 MHz, CDCl3) δ 6.67-6.60 (m, 2 H),
6.48 (dd, J ) 7, 2 Hz, 1 H), 6.15 (br s, 1 H), 4.66 (br s, 2 H),
3.89 (dd, J ) 10, 6 Hz, 1 H), 3.79 (dd, J ) 10, 5 Hz, 1 H),
3.78-3.68 (m, 2 H), 3.53 (app t, J ) 5, 4 Hz, 4 H), 3.48 (dd, J
) 11, 3 Hz, 1 H), 2.92 (dd, J ) 12, 2 Hz, 1 H), 2.7 (s, 2 H), 2.74
(app dt, J ) 12, 3 Hz, 1 H), 2.65 (br d, J ) 11 Hz, 1 H), 2.56
(dd, J ) 10, 12 Hz, 1 H), 2.27 (br s, 4 H), 1.84 (br s, 1 H); 13C
NMR (75 MHz, CDCl3) δ 147.3, 143.6, 132.0, 123.9, 122.5,
121.3, 119.9, 115.2, 75.2, 71.1, 68.3, 67.8, 67.2, 62.1, 53.8, 48.6,
46.0; EIMS (70 eV) m/z (relative intensity) 346 (M+, 2), 260
(24), 259 (100), 161 (36), 160 (55), 131 (28), 115 (22), 100 (86),
98 (87), 86 (11), 72 (41), 70 (13), 57(13), 56 (96).
(R,S)-2-[[(p-Tolylsu lfon yl)oxy]m eth yl]m or p h olin e (24).
(R,S)-4-Benzyl-2-[[(p-tolylsulfonyl)oxy]methyl]morpholine (23;21
4.0 g, 11 mmol) was dissolved in acetic acid (150 mL) and
hydrogenated over palladium (10%) on activated carbon (0.60
g) at room temperature and atmospheric pressure until H2
uptake ceased (3 h). The catalyst was filtered off and the

A New Selective Rat 5-HT1B Receptor Antagonist
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 11 1941
The mesylate precipitated out of tetrahydrofuran/diethyl
saturated with NH3 (100:15) as the eluent, and the amine was
converted into the hydrochloride from diethyl ether/methylene
chloride to give the title compound as white crystals: yield
33%; mp 199-200 °C; 1H NMR (300 MHz, CDCl3) δ 7.17 (t, J
) 2 Hz, 1 H), 6.92-6.87 (m, 2 H), 6.73 (dd, J ) 6, 3 Hz, 1 H),
4.84 (d, J ) 1 Hz, 2 H), 3.90-3.80 (m, 2 H), 3.24 (app dd, J )
12, 3 Hz, 1 H), 3.03 (app dt, J ) 12, 4 Hz, 1 H), 2.61 (dt, J )
12, 3 Hz, 1 H), 2.47 (dd, J ) 12, 10 Hz, 1 H), 2.11-1.97 (m, 2
H), 1.95-1.84 (m, 1 H), 1.76-1.65 (m, 1 H), 1.59-1.43 (m, 1
H), 1.32-1.17 (m, 1 H); 13C NMR (50 MHz, CDCl3) δ 147.4,
143.8, 138.8, 122.0, 120.8, 120.4, 117.3, 116.3, 103.2, 72.3, 64.2,
49.3, 46.4, 36.4, 27.4, 25.2; EIMS (70 eV) m/z (relative
intensity) 270 (M+, 94), 172 (11), 116 (13), 98 (100), 89 (29),
69 (35). Anal. (C16H18N2O2‚HCl) C, H, N.
ether: yield 1.3 g (42%) of off-white crystals; mp 139-141 °C;
[R]21 +2.3° (c 1.7, methanol); HPLC purity 99.4% (Novapak
D
C18 (3.9 × 150 mm), 0.05 M phosphate buffer (pH 4.6)/
acetonitrile, 9:1, v/v). Anal. (C19H26N2O4‚CH3SO3H‚H2O) C,
H, N.
(S)-(-)-2-[[[3-(Mor p h olin om et h yl)-2H -ch r om en -8-yl]-
oxy]m eth yl]m or ph olin e Hydr och lor ide ((S)-25). The com-
pound was prepared as described for its antipode (R)-25. The
spectroscopic data were in accordance with its enantiomer:
[R]21D +1.1° (c 1.2, methanol). The hydrochloride precipitated
out of tetrahydrofuran: mp 156-158 °C; [R]21 -1.6° (c 1.2,
D
methanol). Anal. (C19H26N2O4‚HCl‚1.5H2O) C, H; N: calcd,
7.4; found, 6.9.
(R,S)-2-[[(3-(Mor p h olin oca r b on yl)-2H -ch r om en -8-yl]-
oxy]m eth yl]m or p h olin e Oxa la te ((R,S)-30). The com-
pound was prepared as described for (R)-25. The crude
product was purified on a silica gel column using methylene
chloride/methanol/ammonium hydroxide (95:5:0.5) as the elu-
ent, and the amine was converted into the oxalate from diethyl
ether/tetrahydrofuran to give the title compound as white
crystals: yield 28%; mp 118 °C (sinters); 1H NMR (300 MHz,
CDCl3) δ 6.90 (dd, J ) 8, 2 Hz, 1 H), 6.85 (t, J ) 8 Hz, 1 H),
6.73 (dd, J ) 7, 2 Hz, 1 H), 6.58 (t, J ) 1 Hz, 1 H), 4.91 (d, J
) 1 Hz, 2 H), 4.06 (dd, J ) 10, 6 Hz, 1 H), 3.98-3.83 (m, 3 H),
3.74-3.61 (m, 9 H), 3.07 (dd, J ) 12, 2 Hz, 1 H), 2.97-2.79
(m, 2 H), 2.73 (dd, J ) 12, 10 Hz, 1 H), 1.82 (br s, 1 H); 13C
NMR (75 MHz, CDCl3, 50 °C) δ 167.9, 147.8, 144.5, 127.0,
126.9, 122.2, 122.0, 121.2, 116.8, 75.1, 71.1, 68.2, 67.1, 66.2,
48.5, 46.0, 45; EIMS (70 eV) m/z (relative intensity) 360 (M+,
100), 261 (42), 176 (14), 175 (12), 100 (42), 86 (17), 70 (23), 56
(84). Anal. (C19H24N2O5‚C2H2O4‚1/2H2O) C, H, N.
(R,S)-2-[[[3-(Mor ph olin om eth yl)-2H-ch r om en -8-yl]oxy]-
m eth yl]m or p h olin e Oxa la te ((R,S)-25). The compound was
prepared as described for (R)-25. The spectroscopic data were
in accordance with its enantiomers. The oxalate precipitated
out of tetrahydrofuran: yield 32%; mp 116 °C (sinters). Anal.
(C19H26N2O4‚C2H2O4‚H2O) C, H, N.
(R,S)-2-[[(2-Cyan o-3,4-dih ydr o-5-n aph th yl)oxy]m eth yl]-
m or p h olin e Hyd r och lor id e ((R,S)-26). The compound was
prepared as described for (R)-25 (yield 92%). An analytical
sample was converted into the hydrochloride and was recrys-
tallized from ethanol to give the title compound as white
crystals: mp 185-187 °C; 1H NMR (300 MHz, CDCl3) δ 7.20-
7.12 (m, 2 H), 6.87 (d, J ) 8 Hz, 1 H), 6.78 (d, J ) 8 Hz, 1 H),
4.06-3.83 (m, 4 H), 3.69 (app dt, J ) 11, 3 Hz, 1 H), 3.05-
2.86 (m, 5 H), 2.78 (app dd, J ) 12, 10 Hz, 1 H), 2.50 (app dt,
J ) 8, 2 Hz, 2 H), 2.07 (br s, 1 H); 13C NMR (50 MHz, CDCl3)
δ 155.3, 141.4, 132.0, 127.3, 123.5, 120.9, 119.6, 113.9, 109.7,
74.9, 69.6, 68.0, 48.4, 45.8, 24.1, 19.1; EIMS (70 eV) m/z
(relative intensity) 270 (M+, 52), 115 (11), 100 (100), 86 (26),
70 (30). Anal. (C16H18N2O2‚HCl‚1/2H2O) C, H, N.
(R,S)-2-[[(3-Cya n o-2H-ch r om en -8-yl)oxy]m eth yl]m or -
p h olin e Hyd r och lor id e ((R,S)-27). The compound was
prepared as described for (R)-25. The crude product was
purified on a silica gel column using ethyl acetate/methanol/
ammonium hydroxide (80:20:1) as the eluent to give the base
as a viscous oil: yield 92%; 1H NMR (300 MHz, CDCl3) δ 7.17
(t, J ) 1 Hz, 1 H), 6.96 (dd, J ) 8, 2 Hz, 1 H), 6.89 (t, J ) 8
Hz, 1 H), 6.75 (dd, J ) 8, 2 Hz, 1 H), 4.85 (d, J ) 1 Hz, 2 H),
4.04 (dd, J ) 10, 6 Hz, 1 H), 3.98-3.82 (m, 3 H), 3.66 (dt, J )
11, 3 Hz, 1 H), 3.05 (dd, J ) 12, 2 Hz, 1 H), 2.97-2.80 (m, 2
H), 2.73 (dd, J ) 12, 10 Hz, 1 H), 1.74 (br s, 1 H); 13C NMR
(50 MHz, CDCl3) δ 147.4, 138.9, 122.2, 121.1, 118.1, 116.5,
103.5, 74.9, 71.0, 68.0, 64.5, 48.3, 45.8; EIMS (70 eV) m/z
(relative intensity) 272 (M+, 50), 173 (4), 116 (6), 100 (49), 70
(18), 56 (100). The hydrochloride salt precipitated out of
tetrahydrofuran: mp 158-159 °C. Anal. (C15H16N2O3‚HCl)
C, H, N.
P h a r m a cology. 1. Ra d ioliga n d Bin d in g Stu d ies. Af-
finities for the following receptors were determined as de-
scribed by J ackson et al.27 (the radioligand and tissue in
parentheses): 5-HT1A ([3H]OH-DPAT, rat hippocampus), R1-
adrenoceptors ([3H]prazosin, rat cortex), R2-adrenoceptors ([3H]-
RX821002 ((1,4-[6,7-3H]benzodioxan-2-methoxy-2-yl)-2-imida-
zoline hydrochloride), rat cortex), â-adrenoceptors ([3H]di-
hydroalprenolol, rat cortex), dopamine D1 ([3H]SCH-23390, rat
striatum); dopamine D2 ([3H]raclopride, cell (LtkhD2A) mem-
branes). The following receptors were determined as described
by J ohansson et al.:28 5-HT2A ([3H]ketanserin, rat cortex),
5-HT2C ([3H]mesulergine, rat cortex), 5-HT6 ([3H]-5-HT, cell
(CHOr5-HT6) membranes), 5-HT7 ([3H]-5-HT, cell (CHOr5-
HT7) membranes).
[
125I]Iodocyanopindolol was used as the
ligand for r5-HT1B receptors in rat cerebral cortical membranes
in the presence of 60 µM isoproterenol in order to avoid binding
to â-adrenoceptors as described by Hoyer et al.29 Membranes
from calf caudate were used for the assay of 5-HT1D receptors
with [3H]-5-HT in the presence of 8-OH-DPAT, 100 nM, and
mesulergine, 100 nM, to avoid binding to 5-HT1A and 5-HT2C
receptors according to the method of Heuring and Peroutka;30
5-HT, 10 µM, was used in these three assays to determine the
specific binding. Binding to σ recepors in membranes from
whole rat brains was assayed with [3H]DTG (N,N′-di(o-tolyl)-
guanidine) as described by Ross.31
2. P ota ssiu m -Stim u la ted [3H] Over flow fr om Ra t
Cor t ica l Slices P r eloa d ed w it h [3H]-5-HT. The method
described by Re´nyi et al.15 was used. Slices from occipital
cortex (0.3 × 0.3 mm) preloaded with [3H]-5-HT were super-
fused with freshly oxygenated Krebs-Henseleit’s buffer, pH 7.4,
containing 2.5 µM citalopram at a flow rate of 0.4 mL/min.
After a 50 min washing, 4-min fractions were collected, and
after 62 min a buffer solution containing 25 mM KCl was
administered for 4 min followed by superfusion with the
original buffer. The slices were superfused with the test
compound at appropriate concentrations in the buffer for 72
min. A second addition of 25 mM KCl and the test compound
were administered for 4 min beginning at 98 min, and the
superfusion was continued and stopped at 122 min. The
radioactivities in the fractions and remaining activities in the
slices were counted by liquid scintillation, and the percentage
of fractional release for each fraction was determined. The
(R,S)-2-[[(3-Cya n o-2H-ch r om en -8-yl)oxy]m eth yl]-4-N-
m eth ylm or p h olin e Hyd r och lor id e ((R,S)-28). The com-
pound was prepared as described for (R)-25. The crude
product was purified on a silica gel column using chloroform/
ethanol saturated with NH3 (95:5) as the eluent, and the amine
was converted into the hydrochloride in tetrahydrofuran to
give the title compound as white crystals: yield 40%; mp 198-
1
200 °C; H NMR (300 MHz, CDCl3) δ 7.16 (t, J ) 1 Hz, 1 H),
6.96 (dd, J ) 8, 2 Hz, 1 H), 6.89 (t, J ) 8 Hz, 1 H), 6.75 (dd,
J ) 7, 2 Hz, 1 H), 4.85 (d, J ) 1 Hz, 2 H), 4.15-3.88 (m, 4 H),
3.71 (app dt, J ) 11, 2 Hz, 1 H), 2.85 (app dt, J ) 11, 2 Hz, 1
H), 2.66 (app dq, J ) 3, 11 Hz, 1 H), 2.32 (s, 3 H), 2.17 (dt, J
) 11, 3 Hz, 1 H), 2.00 (dd, J ) 11, 10 Hz, 1 H); 13C NMR (75
MHz, CDCl3) δ 147.8, 144.5, 139.4, 122.6, 121.5, 121.4, 118.4,
117.0, 103.8, 74.1, 71.1, 67.0, 64.6, 57.3, 54.9, 46.5; EIMS (70
eV) m/z (relative intensity) 286 (M+, 71), 114 (100), 89 (22),
84 (18), 72 (43), 71 (34), 70 (32). Anal. (C16H18N2O3‚HCl) C,
H, N.
(R,S)-3-[[(3-Cya n o-2H-ch r om en -8-yl)oxy]m eth yl]p ip er -
id in e Hyd r och lor id e ((R,S)-29). The compound was pre-
pared as described for (R)-25. The crude product was purified
on
a silica gel column using methylene chloride/ethanol

1942 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 11
Berg et al.
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ratio of release in the presence of the test compound after the
second stimulation (S2) to that after the first stimulation (S1)
was determined and expressed as a percentage of the corre-
sponding ratio in the controls without test compound. To
evaluate the intrinsic activity, the test compound and 5-HT
were administered in the same solution.
3. 5-HT Tu r n over in Va r iou s Br a in Region s. The rate
of 5-HT turnover in hypothalamus, hippocampus, frontal
cortex, and striatum in rats was determined as the accumula-
tion of 5-hydroxytryptophan (5-HTP) after treatment with the
5-HTP decarboxylase inhibitor 3-hydroxybenzylhydrazine di-
hydrochloride (NSD 1015), 100 mg/kg sc. The test compound
was injected sc 30 min before NSD 1015, and the rats were
killed 30 min after. The various brain regions were rapidly
dissected out, frozen on dry ice, and stored at -70 °C. 5-HTP,
5-HT, and 5-hydroxyindoleacetic acid (5-HIAA) were analyzed
by HPLC.32
4. Deter m in a tion of Wet Dog Sh a k e Beh a vior . The
number of wet dog shakes, including whole body shake and
head shake, was determined during 60 min, starting 5 min
after the injection of the test compound.15 Groups of 8-10 rats
were used and compared with saline-treated rats (n ) 30).
Ack n ow led gm en t. We thank Charlotte Ahlgren,
Gunilla Ericsson, Ingrid Fagervall, Eva J erning, Su-
sanne Rosqvist, and Maria Sa¨llemark at Astra Arcus
AB and Bjo¨rn Svensson at Astra Pain Control, So¨der-
ta¨lje, for some of the binding values and Sverker
Hansson, Rolf J ohansson, and Carina Stenfors at Astra
Arcus AB for valuable discussions of the manuscript.
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