N-Substituted-2-alkyl- and 2-arylnorapomorphines: Novel, highly active D2 agonists

Article abstract of DOI:10.1016/j.bmc.2009.04.047

Two synthesis routes have been elaborated for the preparation of novel N-substituted-2-alkyl- and 2-arylnorapomorphines. The first one utilizes the traditional methodology of N-substitution of morphinans before acid-catalyzed rearrangements into aporphino

Full text of DOI:10.1016/j.bmc.2009.04.047

Bioorganic & Medicinal Chemistry 17 (2009) 4756–4762
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
N-Substituted-2-alkyl- and 2-arylnorapomorphines: Novel, highly active
D2 agonists
Laura Herm a, Sándor Berényi b, Argo Vonk a, Ago Rinken a, Attila Sipos b,
*
a Institute of Chemistry, University of Tartu, Jakobi 2, 51014 Tartu, Estonia
b Department of Organic Chemistry, University of Debrecen, PO Box 20, H-4010 Debrecen, Hungary
a r t i c l e i n f o
a b s t r a c t
Article history:
Two synthesis routes have been elaborated for the preparation of novel N-substituted-2-alkyl- and 2-
arylnorapomorphines. The first one utilizes the traditional methodology of N-substitution of morphinans
before acid-catalyzed rearrangements into aporphinoids, while our new approach involves the N-substi-
tution directly on the aporphine backbone. The aimed compounds were obtained in similar overall yields
in different synthesis routes and were investigated with respect to their binding affinities and activities to
dopamine D2 and D1 receptors. These studies revealed remarkable affinity and selectivity of some com-
pounds for D2 over D1 receptor subtypes. Partial or full agonist properties were confirmed for all tested
compounds.
Received 3 December 2008
Revised 20 April 2009
Accepted 22 April 2009
Available online 3 May 2009
Dedicated to Professor György Kalaus on the
occasion of his 70th birthday
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Apomorphine derivatives
Suzuki–Miyaura reaction
N-Substitution
N-Oxidation
Dopamine receptor activity
1. Introduction
enantiomers, but does not generate subtype selectivity.3a The
introduction of appropriate moieties to the ring A of aporphine
Different brain dopaminergic systems have been in the focus of
extensive research over many decades now. The need for high
affinity and subtype selective (partial) agonists is connected with
treatment and/or prevention of schizophrenia, Parkinson’s disease,
Tourette’s syndrome, depression, addiction etc.1a It should be
noted that in spite of their similar anatomical distribution in brain
striatal and limbic areas, functions of D1 and D2 receptors are quite
different—at biochemical and as well as at behavioral level.1b How-
ever, high affinity ligands for one of these receptors have often also
similar affinity for the other subtypes, which may cause undesir-
able side effects in patients. Apomorphine (1) (Fig. 1), first synthe-
sized in 1869 from morphine by Matthiessen and Wright, is one of
few approved dopamine receptor drugs, which is in use in treat-
ments of Parkinson’s disease and erectile dysfunction.2
backbone gives rise to the change of the selectivity of com-
pounds.3b The modification of the substituent at amine-type N6
has high size-sensitivity, ethyl- and propyl-substituted compounds
have subnanomolar affinities for D2 receptors, however com-
pounds with isopropyl and larger substituents have thousand time
lower affinities.4a This has made propylnorapomorphine (NPA) a
powerful tool for studies of dopaminergic receptors,4b and an
important matrix for the development of new more subtype-selec-
tive dopaminergic ligands.
In the present paper we report on the combination of two of the
above mentioned approaches and, by varying substituents at posi-
tions N6 and 2, the synthesis of new compounds with nanomolar
affinity for D2 receptors and clear selectivity over D1 receptors
The application of this drug substance has been limited by the
above mentioned lack of selectivity among dopamine receptor sub-
types, and therefore an intensive search for derivatives with higher
subtype selectivity without significant loss of their affinity has
been generated. One approach is to change the stereochemistry
of the compound. Modification of the only chiral center of the mol-
ecule (C6a) results some agonist/antagonist counterparts among
4
6a
7
3
R
5
2
1
Compound
R
H
N
1
2
3
4
H3C
Me
H
Ph
4-OH-Ph
OH
11
10
8
OH
9
* Corresponding author. Tel.: +36 52512900; fax: +36 52486836.
E-mail address: asipos@puma.unideb.hu (A. Sipos).
Figure 1. Structure of apomorphine (1), core structure for design of new
compounds and its 2-substituted derivatives.
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.04.047

L. Herm et al. / Bioorg. Med. Chem. 17 (2009) 4756–4762
Br
4757
Br
based on previous findings regarding significant D2/D1 selectivity
of 2-arylapomorphines 3, 4.5
N
N
Q-I/K2CO3
1. DEAD
H3C
H
The N-substituted noraporphines are traditionally prepared via
the acid-catalyzed rearrangement of the corresponding normor-
phinans.1a,6 Syntheses of these N-substituted derivatives involve
the conversion of N-methyl-substituted opioids to the cyana-
mides,7 carbamates8 or 1,2-dicarbethoxyhydrazinylmethyl-cong-
eners,9 which are subsequently cleaved to give the N-noropioids.
Simple N-alkylation provides the desired substitution.6
However, in morphinans having double bond between C8 and
C14 the formation of cyanamides and carbamates was accompa-
nied by the cleavage of C9–N17 bond;10 due to this reason diethyl
azodicarboxylate (DEAD) was applied.11
O
O
EtOH, reflux
2. Pyridine.HCl/EtOH,
RT
OCH3
Br
OCH3
5
6
Br
Q
Et
Pr
N
7, 9
N
Q
CH3SO 2OH
Q
O
H
8, 10
OH
OCH3
OCH3
7, 8
9, 10
The direct N-demethylation and consequent N-alkylation of
aporphines have not described, however some successful attempts
were published regarding the synthesis of noraporphines.12,13
Scheme 2. Synthesis of N-Et- and N-Pr-2-Br-norapocodeines (9, 10) via Route I.
Br
Br
2. Results and discussion
2.1. Chemistry
O
N
N
H2O2/Na2WO4
FeSO4.7H2O
EtOH
H3C
H3C
H
H
water:1,4-dioxane 1:2
OH
OH
Herewith we report the preparation of 2- and N6-substituted
noraporphines as compounds which have perspective as specific
activators of D2 receptors. The synthesis of N-ethyl and N-propyl-
nor derivatives of 2-substituted apomorphines 2–4 was a reason-
able step forward in the course of development of novel, highly
potent dopamine agonists following from the above-described
observations. The conventional synthesis route to N-substituted
aporphines involves the consecutive N-deprotection and N-alkyl-
ation on morphinan backbone and the acid-catalyzed rearrange-
ment into N-alkyl-noraporphine (Scheme 1, Route I). A modified
route employs direct rearrangement of 6-Br-6-demethoxythebaine
(5) into the apocodeine and performs the transformation of
N-methyl derivatives into N-ethyl or N-propyl-noraporphines
(Scheme 1, Route II). From this point Route II is the same as Route
I. Suzuki–Miyaura cross-coupling steps included in the joint part of
routes were based on our previous experience in the formation of
2- and 3-substituted aporphines.14
The starting product of both synthesis routes is 6-Br-6-demeth-
oxythebaine (5) produced from natural thebaine according to the
procedure elaborated by our research group in 1984.15 The
N-demethylations and N-alkylations of 5 were carried out in the
traditional way applying diethyl azodicarboxylate (DEAD, Scheme
2).16 The acid-catalyzed rearrangement of N-alkyl-nor derivatives
7, 8 provided N-ethyl- and N-propyl-2-bromonorapocodeines (9,
10) in excellent yields.
OCH3
Br
OCH3
11
12
Br
Q
Et
Pr
HN
N
9
Q-I/K2CO3
Q
H
H
OH
OH
10
EtOH, reflux
OCH3
OCH3
13
9-10
Scheme 3. Synthesis of N-Et- and N-Pr-2-Br-norapocodeines (9, 10) via Route II.
al.17 was successfully adopted to aporphine backbone to obtain
N-ethyl and N-propyl congeners as it was previously communi-
cated in details.18 The transformation of 2-bromoapocodeine (11)
into its N-oxide congener 12 (Scheme 3) was achieved with the
application of Na2WO4-catalyzed, H2O2-mediated oxidation in
water:1,4-dioxane mixture (1:2).
The HCl salt of N-oxide 12 was then N-deprotected according to
Scammells’ procedure applying FeSO4ꢀ7H2O in methanol at 0 °C.
Noraporphine 13 was alkylated with the same procedure as in
Route I to reach N-ethyl- and N-propyl-2-bromonorapocodeines
(9, 10). The traditional procedure (Route I) resulted the compounds
9 and 10 in 34% and 38% yields, respectively; while Route II yielded
the same products in 43% and 39%, respectively.
Further steps of joint Routes I and II include the Suzuki–Miya-
ura cross-coupling of aryl halide-type compounds 9 and 10
resulting 2-alkyl- and 2-arylnorapocodeines 14–19 and the
O-demethylation of the apocodeines to form pharmacologically
As an alternative synthesis of compounds 9 and 10 the starting
diene 5 was rearranged into 2-bromoapocodeine 11 and the
N-substitution was achieved on aporphine backbone. The oxida-
tion–cleavage–alkylation sequence proposed by McCamley et
Br
N
Q
O
I.
R
R
Br
Br
N
N
N
OCH3
Br
N
Q
Q
Q
H3C
H
H
O
H
OH
OH
OH
OH
N
OCH3
OCH3
OCH3
H3C
H
OH
II.
OCH3
Scheme 1. Retrosyntheses of N-substituted 2-methyl- and 2-arylnorapomorphines.

4758
L. Herm et al. / Bioorg. Med. Chem. 17 (2009) 4756–4762
R
had also significantly higher subtype selectivity over D1 receptors.
Br
The 83- and 47-fold difference in binding affinity is considered
pharmacologically significant. It is important to mention, that in
the case of 2-(4-hydroxyphenyl) derivatives of apomorphine 22,
25 the influence of the size of substituent in N6 position had quite
marginal role. Here we have found very similar properties for
N-ethyl- (22) and N-propyl- (25) derivatives and N-methyl-deriva-
tive.5a,b The hydrophilic hydroxyl group coupled with 2-phenyl
moiety seems to play crucial role in the binding and generation
of response. Omitting of this group (compounds 21, 24) led to some
decrease of affinity and also to loss of subtype selectivity. Higher
D2/D1 subtype selectivity ratio (>30) was also achieved with 2-O-
substituted apomorphines, but their affinities were at least 10
times lower and they behaved as partial agonists compared to
dopamine.3b
N
N
R-B(OH)2/Pd(PPh3)4
Q
Q
H
H
OH
Ba(OH) 2.8H2O
water:1,4-dioxane 1:4
OH
OCH3
OCH3
14-19
9-10
R
Q
14, 20
Me
Ph
Et
Et
R
15, 21
16, 22
17, 23
18, 24
19, 25
N
Q
4-OH-Ph Et
CH3SO2OH/methionine
H
OH
OH
Me
Ph
Pr
Pr
20-25
4-OH-Ph Pr
Scheme 4. Closing steps of Routes I and II.
3. Conclusion
more interesting apomorphine 20–25 as stable HCl salts (Scheme 4).
These steps are in agreement with parts of our previously
presented methodologies yielding 2-alkyl- and 2-arylapomor-
phines 2–4, no major difference was observed in the reactivity of
aporphines with regard to the change of the substituent at N6.5b,14
In this paper, we have presented two approaches for synthesis
of N-substituted-2-alkyl- and 2-arylnorapomorphines. Besides
the method, utilizing conventional steps towards the N-substitu-
tion of morphinan backbone, a novel synthesis strategy was elabo-
rated achieving N-substitution at aporphine skeleton. Most of the
obtained compounds had high affinity for D2 dopamine receptors
and partial or full agonist properties. Highest affinity, subtype
selectivity and full agonistic properties was achieved with 2-(4-
hydroxyphenyl)- compounds (22, 25). Obtained results indicate
important role of size, localization and lipophilic/hydrophilic moi-
eties of 2-substituents of N-alkyl norapomorphines.
2.2. Pharmacology
The pharmacological properties of synthesized apomorphines
20–25 were studied in model systems expressing D2 and D1 dopa-
mine receptors. The affinities of substances for corresponding
receptors were estimated by their ability to displace the specific
binding of [3H]raclopride and [3H]SCH23390, respectively. The
specificity of ligands was calculated as a ratio of their affinities in
radioligand binding assays for corresponding receptors. The
agonistic properties of compounds were tested by their ability to
4. Experimental
4.1. General
activate [35S]GTP
cS binding to G proteins in CHO cell membranes,
which has been developed as functional assay for D2 receptors.19
All tested apomorphine derivatives had higher affinities towards
D2 receptors, the Ki values being in nanomolar/submicromolar
range, while their Ki values for D1 receptors remaining in submi-
cromolar/micromolar range (Table 1).
Melting points were determined with a Kofler hot-stage appara-
tus and are uncorrected. Thin layer chromatography was per-
formed on precoated Merck 5554 Kieselgel 60 F254 foils using
80% CH2Cl2/20% CH3OH mobile phase. The spots were visualized
with Dragendorff’s reagent. 1H NMR spectra were recorded at
400 MHz, while 13C NMR spectra at 100 MHz, using a Bruker
Avance DPX400 spectrometer; chemical shifts were reported in
ppm (d) from internal TMS and coupling constants (J) were mea-
sured in hertz. Mass spectra (EI and HRMS, 70 eV, m/z) were
obtained on a Jeol DX 303/DA 5000 instrument. Optical rotation
Highest potency and best subtype selectivity was achieved with
2-(4-hydroxyphenyl) derivatives (22, 25). Both of them had more
than fivefold higher affinity for D2 receptors than apomorphine
(1), and in [35S]GTP
cS activation assay they behaved as full ago-
nists in comparison to dopamine (Table 1). These two compounds
Table 1
Binding affinities of synthesized compounds for dopamine D2 and D1 receptors and their potencies and efficacies in activation of D2 receptors
Compound
D2
D1
D2/D1
Versus [3H]raclopride
Activation of [35S]GTP
c
S binding
Efficacy (%)
100
Versus [3H]SCH23390
Specificity (fold)
Ki (nM)
EC50 (nM)
Ki (nM)
Dopamine
1
2
3
197 67
11.5 0.7
20.7*
1425 813
53 2.9
43*
124 23
72 5.6
—
0.6
6.3
—
58
—
1
11.7*
23*
—
—
88*
7.5*
182*
12
4
4.14*
8.5*
755*
20
21
22
23
24
25
115 47
14.0 2.8
1.5 0.1
9.2 0.9
192 46
2.0 0.1
480 28
51 5.2
8.7 0.6
40 8.5
577 93
12.0 2.9
112
3
1340 516
31 1.4
124 2.8
278 5.6
669 172
94 15
72 15
2.2
83
30
3.5
47
112
65
6
4
100
5
99 16
Ki characterizes the ability of a compound to inhibit [3H]raclopride and [3H]SCH23390 binding to D2 and D1 receptors, respectively. EC50 is the ability of compounds to
activate [35S]GTP S binding. Efficacy represents the level of [35S]GTP
S binding activation in comparison with the effect of dopamine. Specificity is the ratio of affinity
c
c
constants of compounds towards D1 and D2 receptors.
*
Data from Ref. 5.

L. Herm et al. / Bioorg. Med. Chem. 17 (2009) 4756–4762
4759
was determined with a Perkin Elmer Model 241 polarimeter. Ele-
mental analyses (C, H, N, S) were obtained on a Carlo Erba
EA1108 analyzer.
4.2.2.2. N-Propyl-2-bromonorapocodeine (10). Off-white solid;
yield: 1069 mg (83%); Rf (80% CH2Cl2/20% CH3OH) 0.67; MS (EI):
m/z (%) 387 (M+, 91), 372 (100), 341 (56); HRMS (EI) m/z (%) calcu-
lated for C20H22BrNO2þ: 387.0907 (M+), found: 387.0915 (M+, 91);
melting point, optical rotation and 1H NMR results were in agree-
ment with data in Ref. 11a. 13C NMR (100 MHz, CDCl3) d = 145.78
(C10), 144.12 (C11), 136.03–112.87 (Ar, 10C), 59.78 (C6), 56.11
(OCH3), 52.45 (N–CH2–CH2–CH3), 49.65 (C5), 35.37 (C7), 27.34
(C4), 24.56 (N–CH2–CH2–CH3), 15.65 (N–CH2–CH2–CH3).
4.2. Route I
4.2.1. N-Alkylation of 6-Br-6-demethoxynorthebaine (6)
Compound
6
(135 mg, 0.39 mmol) and K2CO3 (84 mg,
0.61 mmol) in anhydrous EtOH (10 mL) were stirred under N2 at
80–90 °C. After 20 min, alkyl iodide (0.61 mmol) was dropped
and the reaction mixture was stirred for 24 h at 90 °C. After cooled
to rt, water (20 mL) was added, and the solution was extracted
with ethyl acetate (3 ꢁ 10 mL). The combined organic layer was
washed with brine, dried with sodium sulfate, filtered and evapo-
rated in vacuo to yield pure oily product.
4.2.3. Suzuki–Miyaura cross-coupling of compounds 9, 10
A mixture of the bromo-derivative (3.00 mmol), the aryl- or
methylboronic acid (3.00 mmol), Pd(PPh3)4 (0.15 mmol) and
Ba(OH)2ꢀ8H2O (3.00 mmol) was boiled in 1,4-dioxane:H2O = 4:1
under reflux for 30 min. After evaporation at reduced pressure
the residue was dissolved in chloroform (20 mL) and filtered. The
filtrate was evaporated and the oily crude product was purified
by flash chromatography (silica, 80% CH2Cl2/20% CH3OH) to yield
aryl and alkyl derivatives.
4.2.1.1. N-Ethyl-6-bromo-6-demethoxynorthebaine (7). Slightly
yellow oil; yield: 120 mg (81%); ½a D25
ꢃ 194 (c 0.1, chloroform); Rf
ꢂ
(80% CH2Cl2/20% CH3OH) 0.52; MS (EI): m/z (%) 373 (M+, 100),
357 (46), 303 (67); HRMS (EI) m/z (%) calculated for
C19H20BrNO2þ: 373.0756 (M+), found: 374.0741 (M+, 100); dH
(400 MHz CDCl3) 6.52–6.44 (2H, 2d, C1–H, C2–H, J1–2 7.9), 6.37
(1H, C7–H, J7–8 6.4), 5.54 (1H, d, C8–H, J7–8 6.5), 4.78 (1H, s, C5–
Ha), 3.77–3.71 (4H, m, C9–H, C3–OCH3), 2.94–2.09 (7H, m, C10–Ha,
C10–Hb, C15–Hb, C16–Ha, C16–Hb, –NCH2), 2.01 (1H, td, C15–Ha,
J15a,15b;16a,16b 10.8, J15a,15b 4.3), 1.07 (1H, t, N–CH2–CH3, J 4.7); dC
(100 MHz CDCl3) 146.72 (C3), 145.31 (C4), 136.32 (C14), 134.23–
111.38 (6C, aromatic, C6, C7,C8), 87.56 (C9), 61.84 (C9), 56.34 (C6–
OCH3), 48.14 (C16), 47.24 (N–CH2–), 44.61 (C13), 34.39 (C15),
30.69 (C10), 17.24 (N–CH2–CH3).
4.2.3.1. N-Ethyl-2-methylnorapocodeine (14). Pale yellow solid;
mp: 151–153 °C; yield: 769 mg (83%); Rf (80% CH2Cl2/20% CH3OH)
0.69; ½a 2D5
ꢂ
ꢃ 129 (c 0.1, methanol); MS (EI): m/z (%) 309 (M+, 100),
þ
294 (60), 267 (53); HRMS (EI) m/z (%) calculated for C20H23NO2
:
309.1802 (M+), found: 309.1832 (M+, 100). Anal. Calcd for
C20H23NO2: C, 77.64; H, 7.49; N, 4.53. Found: C, 77.48; H, 7.68;
N, 4.29; 1H NMR (400 MHz, CDCl3) d = 7.12 (1H, s, C1–H), 6.99
(1H, s, C3–H), 6.68–6.61 (2H, 2d, C8–H, C9–H, J8–9 8.0), 6.05 (1H,
br s, OH), 4.29 (1H, dt, H6a, J6a–7a 4.8, J6a–7b 1.7), 3.82 (3H, s, O–
CH3), 3.20–2.49 (6H, m, H4a, H4b, H5a, H5b, H7a, H7b), 2.41–2.37
(4H, m, N–CH2–CH3, C2–CH3), 0.98 (3H, t, N–CH2–CH3, J 4.9); 13C
NMR (100 MHz, CDCl3) d = 145.36 (C10), 144.79 (C11), 134.46–
113.59 (Ar, 10C), 59.31 (C6), 56.12 (OCH3), 50.76 (C5), 46.94 (N–
CH2–CH3), 35.30 (C7), 27.69 (C4), 15.95 (N–CH2-CH3).
4.2.1.2. N-Propyl-6-bromo-6-demethoxynorthebaine (8). Col-
ourless oil; yield: 131 mg (87%); Rf (80% CH2Cl2/20% CH3OH)
0.44; optical rotation and 1H NMR results were in agreement with
data in Ref. 14a. MS (EI): m/z (%) 387 (M+, 100), 372 (43), 334 (76);
HRMS (EI) m/z (%) calculated for C20H22BrNO2þ: 387.0907 (M+),
found: 387.0914 (M+, 100); dC (100 MHz CDCl3) 146.52 (C3),
145.88 (C4), 135.78 (C14), 133.71–114.32 (6C, aromatic, C6, C7,C8),
87.43 (C9), 60.91 (C9), 56.47 (C6–OCH3), 47.69 (C16), 47.40 (N–
CH2–), 44.16 (C13), 34.71 (C15), 30.60 (C10), 22.76 (N–CH2–CH2–
CH3), 13.33 (N–CH2–CH2–CH3).
4.2.3.2. N-Ethyl-2-phenylnorapocodeine (15). Yellow solid; mp:
143–145 °C; yield: 879 mg (79%); Rf (80% CH2Cl2/20% CH3OH)
0.71; ½a 2D5
ꢂ
ꢃ 137 (c 0.1, methanol); MS (EI): m/z (%) 371 (M+,
100), 356 (87), 321 (59); HRMS (EI) m/z (%) calculated for
C25H25NO2þ: 371.1958 (M+), found: 371.1939 (M+, 100). Anal. Calcd
for C25H25NO2: C, 80.83; H, 6.78; N, 3.77. Found: C, 80.58; H, 6.81;
N, 3.59; 1H NMR (400 MHz, CDCl3) d = 7.44–7.04 (7H, m, C2–Ar, C1–
H, C3–H), 6.65–6.58 (2H, 2d, C8–H, C9–H, J8–9 7.8), 6.10 (1H, br s,
OH), 4.20 (1H, dt, H6a, J6a–7a 4.6, J6a–7b 1.5), 3.80 (3H, s, O–CH3),
3.24–2.42 (8H, m, H4a, H4b, H5a, H5b, H7a, H7b, N–CH2–CH3), 0.98
(3H, t, N–CH2–CH3, J 4.7); 13C NMR (100 MHz, CDCl3) d = 145.68
(C10), 144.53 (C11), 136.27–113.21 (Ar, 16C), 58.11 (C6), 56.48
(OCH3), 50.17 (C5), 47.09 (N–CH2–CH3), 35.32 (C7), 28.43 (C4),
14.45 (N–CH2-CH3).
4.2.2. Acid-catalyzed rearrangement of compounds 7, 8
A mixture of the diene (3.37 mmol) and methanesulfonic acid
(5 mL) was stirred for 20 min at 0 °C and further 20 min at 90 °C.
Then the reaction mixture was added dropwise, with stirring and
external ice-cooling, to a solution of potassium hydrogen carbon-
ate (10 g) in water (50 mL). After extraction with chloroform
(3 ꢁ 15 mL), the combined extracts were washed with saturated
brine, dried over MgSO4, and concentrated under reduced pressure.
Crude products were purified with re-crystallization.
4.2.3.3. N-Ethyl-2-(4-hydroxyphenyl)-norapocodeine (16). Off-
white solid; mp: 167–169 °C; yield: 836 mg (72%); Rf (80% CH2Cl2/
4.2.2.1. N-Ethyl-2-bromonorapocodeine (9). Off-white solid;
mp: 167–169 °C; yield: 996 mg (79%); Rf (80% CH2Cl2/20% CH3OH)
20% CH3OH) 0.52; ½a D25
ꢃ 127 (c 0.1, methanol); MS (EI): m/z (%)
ꢂ
387 (M+, 81), 372 (65), 356 (100), 320 (35); HRMS (EI) m/z (%) calcu-
lated for C25H25NO3þ: 387.1907 (M+), found: 387.1900 (M+, 81).
Anal. Calcd for C25H25NO3: C, 77.49; H, 6.50; N, 3.61. Found: C,
77.44; H, 6.65; N, 3.49; 1H NMR (400 MHz, CDCl3) d = 7.47 (1H, s,
C1–H), (7.41–7.11 (5H, m, C2–Ar, C3–H), 6.63–6.57 (2H, 2d, C8–H,
C9–H, J8–9 8.0), 6.22 (2H, 2 br s, C11–OH, C4’–OH), 4.09 (1H, dt, H6a,
J6a–7a 4.9, J6a–7b 1.8), 3.86 (3H, s, O–CH3), 3.17–2.38 (8H, m, H4a,
0.60; ½a 2D5
ꢂ
ꢃ 116 (c 0.1, methanol); MS (EI): m/z (%) 373 (M+, 87),
358 (100), 310 (70); HRMS (EI) m/z (%) calculated for
C19H20BrNO2þ: 373.0750 (M+), found: 373.0732 (M+, 87); 1H NMR
(400 MHz, CDCl3) d = 7.75 (1H, s, C1–H), 7.64 (1H, s, C3–H), 6.63–
6.57 (2H, 2d, C8–H, C9–H, J8–9 8.3), 6.12 (1H, br s, OH), 4.21 (1H,
dt, H6a, J6a–7a 5.1, J6a–7b 1.4), 3.77 (3H, s, O–CH3), 3.17–2.44 (6H,
m, H4a, H4b, H5a, H5b, H7a, H7b), 2.39 (2H, dd, N–CH2–CH3, J 4.9),
H4b, H5a, H5b, H7a, H7b, N–CH2–CH3), 1.00 (3H, t, N–CH2–CH3, J
13
4.8); 13C NMR (100 MHz, CDCl3)
4.8); C NMR (100 MHz, CDCl3) d = 160.01 (C4 –OH), 146.79 (C10),
0
1.01 (3H, t, N–CH2–CH3,
J
d = 145.10 (C10), 144.41 (C11), 135.21–114.57 (Ar, 10C), 59.33
(C6), 56.44 (OCH3), 50.41 (C5), 47.13 (N–CH2–CH3), 35.70 (C7),
27.81 (C4), 17.13 (N–CH2–CH3).
144.47 (C11), 136.71–114.48 (Ar, 15C), 57.92 (C6), 56.24 (OCH3),
50.04 (C5), 47.66 (N–CH2–CH3), 35.32 (C7), 28.11 (C4), 15.12
(N–CH2–CH3).

4760
L. Herm et al. / Bioorg. Med. Chem. 17 (2009) 4756–4762
4.2.3.4. N-Propyl-2-methylnorapocodeine (17). Pale yellow so-
lid; mp: 147–149 °C; yield: 755 mg (77%); Rf (80% CH2Cl2/20%
296.1645 (M+ꢃCl), found: 296.1662 (M+ꢃCl, 100). Anal. Calcd for
C19H22ClNO2: C, 68.77; H, 6.68; N, 4.22. Found: C, 68.59; H, 6.69;
N, 4.11; 1H NMR (400 MHz, DMSO-d6) d = 7.07 (1H, s, C1–H), 6.94
(1H, s, C3–H), 6.65–6.59 (2H, 2d, C8–H, C9–H, J8–9 8.1), 6.01 (2H, 2
br s, OH), 4.11 (1H, dt, H6a, J6a–7a 4.5, J6a–7b 1.4), 3.15–2.43 (6H,
m, H4a, H4b, H5a, H5b, H7a, H7b), 2.37–2.32 (4H, m, N–CH2–CH3,
C2–CH3), 0.96 (3H, t, N–CH2–CH3, J 4.4); 13C NMR (100 MHz,
DMSO-d6) d = 145.11 (C10), 144.89 (C11), 136.43–115.18 (Ar, 10C),
59.12 (C6), 50.23 (C5), 46.39 (N–CH2–CH3), 35.66 (C7), 27.61 (C4),
14.58 (N–CH2-CH3).
CH3OH) 0.69; ½a 2D5
ꢃ 117 (c 0.1, methanol); MS (EI): m/z (%) 323
ꢂ
(M+, 100), 308 (76), 277 (86); HRMS (EI) m/z (%) calculated for
C21H25NO2þ: 323.1958 (M+), found: 323.1969 (M+, 100). Anal. Calcd
for C21H25NO2: C, 77.98; H, 7.79; N, 4.33. Found: C, 77.69; H, 7.87;
N, 4.29; 1H NMR (400 MHz, CDCl3) d = 7.17 (1H, s, C1–H), 6.91 (1H,
s, C3–H), 6.71–6.68 (2H, 2d, C8–H, C9–H, J8–9 8.1), 6.12 (1H, br s,
OH), 4.07 (1H, dt, H6a, J6a–7a 4.5, J6a–7b 1.3), 3.84 (3H, s, O–CH3),
3.26–2.46 (6H, m, H4a, H4b, H5a, H5b, H7a, H7b), 2.42–2.34 (4H,
m, N–CH2–CH2–CH3, C2–CH3), 1.38 (2H, dt, N–CH2–CH2–CH3, J
4.7,
J
1.4), 0.88 (3H, t, N–CH2–CH2–CH3,
J
4.7); 13C NMR
4.2.4.2. N-Ethyl-2-phenylnorapomorphine hydrochloride (21ꢀ
HCl). Grey, needle shape crystals; mp: >260 °C; yield: 1446 mg
(100 MHz, CDCl3) d = 145.44 (C10), 144.67 (C11), 135.83–115.45
(Ar, 10C), 58.70 (C6), 56.45 (OCH3), 51.84 (N–CH2–CH2–CH3),
49.32 (C5), 35.75 (C7), 28.34 (C4), 22.32 (N–CH2-CH2–CH3), 13.87
(N–CH2–CH2-CH3).
(79%); Rf free base (80% CH2Cl2/20% CH3OH) 0.33; ½a D25
ꢃ 193 (c
ꢂ
0.1, DMSO); MS (EI): m/z (%) 358 (M+ꢃCl, 100), 320 (81), 298
(34); HRMS (EI) m/z (%) calculated for C24H24NO2þ: 368.1802
(M+ꢃCl), found: 368.1789 (M+ꢃCl, 100). Anal. Calcd for
C24H24ClNO2: C, 73.18; H, 6.14; N, 3.56. Found: C, 73.04; H, 6.27;
N, 3.42; 1H NMR (400 MHz, DMSO-d6) d = 7.37–7.01 (7H, m, C2-
Ar, C1–H, C3–H), 6.61–6.56 (2H, 2d, C8–H, C9–H, J8–9 8.1), 6.10
(2H, 2 br s, OH), 4.08 (1H, dt, H6a, J6a–7a 4.7, J6a–7b 1.8), 3.29–2.41
(6H, m, H4a, H4b, H5a, H5b, H7a, H7b), 2.36 (2H, dd, N–CH2–CH3, J
4.8), 1.03 (3H, t, N–CH2–CH3, J 4.8); 13C NMR (100 MHz, DMSO-
d6) d = 145.41 (C10), 144.59 (C11), 137.18–114.76 (Ar, 16C), 58.65
(C6), 50.40 (C5), 47.10 (N–CH2–CH3), 35.39 (C7), 28.18 (C4), 14.89
(N–CH2–CH3).
4.2.3.5. N-Propyl-2-phenylnorapocodeine (18). Yellow solid;
mp: 139–141 °C; yield: 970 mg (84%); Rf (80% CH2Cl2/20% CH3OH)
0.77; ½a 2D5
ꢂ
ꢃ 136 (c 0.1, methanol); MS (EI): m/z (%) 385 (M+, 100),
þ
370 (89), 349 (56); HRMS (EI) m/z (%) calculated for C26H27NO2
:
385.2115 (M+), found: 385.2126 (M+, 100). Anal. Calcd for
C26H27NO2: C, 81.01; H, 7.06; N, 3.63. Found: C, 80.82; H, 7.24; N,
3.48; 1H NMR (400 MHz, CDCl3) d = 7.40–7.14 (7H, m, C2–Ar, C1–
H, C3–H), 6.63–6.57 (2H, 2d, C8–H, C9–H, J8–9 8.0), 6.02 (1H, br s,
OH), 4.09 (1H, dt, H6a, J6a-7a 4.4, J6a-7b 1.4), 3.81 (3H, s, O–CH3),
3.26–2.46 (6H, m, H4a, H4b, H5a, H5b, H7a, H7b), 2.30 (2H, t, N–
CH2–CH2–CH3, J 4.4), 1.41 (2H, dt, N–CH2–CH2–CH3, J 4.7, J 1.4),
0.91 (3H, t, N–CH2–CH2–CH3, J 4.7); 13C NMR (100 MHz, CDCl3)
d = 145.79 (C10), 144.17 (C11), 136.43–114.95 (Ar, 16C), 59.02
(C6), 56.47 (OCH3), 50.67 (N–CH2–CH2–CH3), 49.26 (C5), 35.76
(C7), 28.93 (C4), 21.76 (N–CH2-CH2–CH3), 12.93 (N–CH2–CH2-CH3).
4.2.4.3. N-Ethyl-2-(4-hydroxyphenyl)-norapomorphine hydro-
chloride (22ꢀHCl). Green, cubic crystals; mp: 203–205 °C; yield:
1410 mg (74%); Rf free base (80% CH2Cl2/20% CH3OH) 0.23;
½
a 2D5
ꢂ
ꢃ 169 (c 0.1, DMSO); MS (EI): m/z (%) 374 (M+ꢃCl, 100), 331
(62), 307 (34), 276 (23); HRMS (EI) m/z (%) calculated for
C24H24NO3þ: 374.1751 (M+ꢃCl), found: 374.1766 (M+ꢃCl, 100).
Anal. Calcd for C24H24ClNO3: C, 70.32; H, 5.90; N, 3.42. Found: C,
70.02; H, 5.98; N, 3.19; 1H NMR (400 MHz, DMSO-d6) d = 7.44
(1H, s, C1–H), 7.38–7.09 (5H, m, C2-Ar, C3–H), 6.68–6.61 (2H, 2d,
C8–H, C9–H, J8–9 7.9), 6.14 (3H, 3 br s, C10–OH, C11–OH, C4’–OH),
4.04 (1H, dt, H6a, J6a–7a 4.4, J6a–7b 1.6), 3.23–2.41 (6H, m, H4a,
H4b, H5a, H5b, H7a, H7b), 2.34 (2H, dd, N–CH2–CH3, J 4.8), 0.98
4.2.3.6. N-Propyl-2-(4-hydroxyphenyl)-norapocodeine (19). White
solid; mp: 169–171 °C; yield: 818 mg (68 %); Rf (80% CH2Cl2/20%
CH3OH) 0.47; ½a 2D5
ꢂ
ꢃ 146 (c 0.1, methanol); MS (EI): m/z (%) 401 (M+,
80), 386 (100), 349 (67); HRMS (EI) m/z (%) calculated for
C26H27NO3þ: 401.2064 (M+), found: 401.2047 (M+, 80). Anal. Calcd
for C26H27NO3: C, 77.78; H, 6.78; N, 3.49. Found: C, 77.49; H, 6.84; N,
3.28; 1H NMR (400 MHz, CDCl3) d = 7.43 (1H, s, C1–H), (7.37–7.11
(3H, m, C2-Ar, C3–H), 6.88–6.80 (2H, m, C2-Ar), 6.64–6.59 (2H, 2d, C8–
H, C9–H, J8–9 7.8), 6.18 (2H, 2 br s, C11–OH, C4’–OH), 4.07 (1H, dt, H6a,
J6a–7a 4.5, J6a–7b 1.7), 3.87 (3H, s, O–CH3), 3.29–2.41 (6H, m, H4a, H4b,
H5a, H5b, H7a, H7b), 2.36 (2H, t, N–CH2–CH2–CH3, J 4.7), 1.46 (2H. dt,
(3H, t, N–CH2–CH3,
J
4.8); 13C NMR (100 MHz, DMSO-d6)
0
d = 157.71 (C4 –OH), 145.72 (C10), 144.55 (C11), 136.12–114.62
(Ar, 15C), 57.30 (C6), 49.69 (C5), 47.34 (N–CH2–CH3), 35.39 (C7),
28.39 (C4), 14.83 (N–CH2-CH3).
N–CH2–CH2–CH3, J 4.6, J 1.9), 0.98 (3H, t, N–CH2–CH2–CH3, J 4.7); 13
C
4.2.4.4. N-Propyl-2-methylnorapomorphine hydrochloride (23ꢀ
HCl). Reddish brown, plate shape crystals; mp: >260 °C; yield:
1306 mg (81%); Rf free base (80% CH2Cl2/20% CH3OH) 0.37;
NMR (100 MHz, CDCl3) d = 158.56 (C4’–OH), 146.36 (C10), 144.22
(C11), 137.84–113.12 (Ar, 16C), 58.73 (C6), 56.32 (OCH3), 53.01 (N–
CH2–CH2–CH3), 49.56 (C5), 35.70 (C7), 28.99 (C4), 22.34 (N–CH2–CH2–
CH3), 12.18 (N–CH2–CH2–CH3).
½
a 2D5
ꢂ
ꢃ 167 (c 0.1, DMSO); MS (EI): m/z (%) 310 (M+ꢃCl, 100), 288
þ
(71), 277 (90); HRMS (EI) m/z (%) calculated for C20H24NO2
:
310.1802 (M+ꢃCl), found: 310.1810 (M+ꢃCl, 100). Anal. Calcd for
C20H24ClNO2: C, 69.49; H, 6.99; N, 4.05. Found: C, 69.18; H, 7.09;
N, 3.90; 1H NMR (400 MHz, DMSO-d6) d = 7.14 (1H, s, C1–H), 6.96
(1H, s, C3–H), 6.59–6.54 (2H, 2d, C8–H, C9–H, J8–9 7.9), 6.10 (2H, 2
br s, C10–OH, C11–OH), 4.05 (1H, dt, H6a, J6a-7a 4.6, J6a-7b 1.4),
3.36–2.43 (6H, m, H4a, H4b, H5a, H5b, H7a, H7b), 2.38–2.30 (4H,
m, N–CH2–CH2–CH3, C2–CH3), 1.32 (2H. dt, N–CH2–CH2–CH3, J
4.2.4. O-Demethylation of norapocodeines 14–19
A
mixture of the apocodeine (4.65 mmol), methionine
(1000 mg, 6.70 mmol) and CH3SO2OH (4 mL) was boiled at 90 °C
for 2 h. After cooling, the pH of the mixture was set to 10 by con-
centrated NH3 solution and extracted with chloroform (3 ꢁ 15 mL).
The organic layers were collected, washed with brine, dried over
anhydrous MgSO4 and evaporated. The residue was subjected to
silica gel column chromatography. Elution with chloroform:meth-
anol = 1:1 gave apomorphines which was immediately trans-
formed into stable HCl salt by ethanol saturated with HCl gas.
4.4,
J 1.5), 0.91 (3H, t, N–CH2–CH2–CH3, J
4.5); 13C NMR
(100 MHz, DMSO-d6) d = 146.05 (C10), 144.67 (C11), 136.12–
114.39 (Ar, 10C), 58.37 (C6), 50.93 (N–CH2–CH2–CH3), 49.39 (C5),
35.37 (C7), 28.72 (C4), 23.17 (N–CH2–CH2–CH3), 14.09 (N–CH2–
CH2–CH3).
4.2.4.1. N-Ethyl-2-methylnorapomorphine hydrochloride (20ꢀ
HCl). Greenish gray, cubic crystals; mp: 256–258 °C; yield:
1249 mg (81%); Rf free base (80% CH2Cl2/20% CH3OH) 0.29;
4.2.4.5. N-Propyl-2-phenylnorapomorphine hydrochloride (24ꢀ
HCl). Green, plate shape crystals; mp: >260 °C; yield: 1611 mg
½
a 2D5
ꢂ
ꢃ 187 (c 0.1, DMSO); MS (EI): m/z (%) 296 (M+ꢃCl, 100), 234
(85%); Rf free base (80% CH2Cl2/20% CH3OH) 0.39; ½a D25
ꢃ 149 (c
ꢂ
(61), 201 (59); HRMS (EI) m/z (%) calculated for C19H22NO2
:
0.1, methanol); MS (EI): m/z (%) 372 (M+ꢃCl, 100), 351 (45), 324
þ

L. Herm et al. / Bioorg. Med. Chem. 17 (2009) 4756–4762
4761
(59); HRMS (EI) m/z (%) calculated for C25H26NO2þ: 372.1958
(M+ꢃCl), found: 372.1969 (M+ꢃCl, 100). Anal. Calcd for
C25H26ClNO2: C, 73.71; H, 6.42; N, 3.43. Found: C, 73.49; H, 6.59;
N, 3.18; 1H NMR (400 MHz, DMSO-d6) d = 7.34–7.05 (7H, m, C2–
Ar, C1–H, C3–H), 6.57–6.52 (2H, 2d, C8–H, C9–H, J8–9 8.2), 5.98
(2H, 2 br s, C10–OH, C11–OH), 4.12 (1H, dt, H6a, J6a–7a 4.5, J6a–7b
1.6), 3.33–2.42 (6H, m, H4a, H4b, H5a, H5b, H7a, H7b), 2.34 (2H, t,
N–CH2–CH2–CH3, J 4.5), 1.45 (2H. dt, N–CH2–CH2–CH3, J 4.6, J
1.7), 0.95 (3H, t, N–CH2–CH2–CH3, J 4.6); 13C NMR (100 MHz,
DMSO-d6) d = 145.02 (C10), 144.46 (C11), 135.67–114.32 (Ar, 16C),
59.60 (C6), 51.18 (N–CH2–CH2–CH3), 49.46 (C5), 35.67 (C7), 28.23
(C4), 22.05 (N–CH2-CH2–CH3), 13.37 (N–CH2–CH2-CH3).
H7a, H7b, NH); dC (100 MHz CDCl3) 146.78 (C10), 144.89 (C11),
135.93–114.22 (Ar, 10C), 56.47 (OCH3), 53.61 (C6), 43.27 (C5),
36.10 (C7), 29.01 (C4).
4.3.2. N-Alkylation of 2-bromonorapocodeine (12)
4.3.2.1. N-Ethyl-2-bromonorapocodeine (9). The N-ethylation of
compound 12 (710 mg, 2 mmol) was carried out according to the
method described in Section 4.2.1 to obtain 612 mg of 9 (82%).
4.3.2.2. N-Propyl-2-bromonorapocodeine (10). The N-propyla-
tion of compound 12 (710 mg, 2 mmol) was carried out according
to the method described in Section 4.2.1 to obtain 581 mg of 10
(75%).
4.2.4.6. N-Propyl-2-(4-hydroxyphenyl)-norapomorphine hydro-
chloride (25ꢀHCl). Grey, cubic crystals; mp: 195–198 °C; yield:
1438 mg (73%); Rf free base (80% CH2Cl2/20% CH3OH) 0.21;
4.4. Pharmacology
½
a 2D5
ꢂ
ꢃ 173 (c 0.1, methanol); MS (EI): m/z (%) 388 (M+ꢃCl, 67),
Chinese hamster ovary cells (CHO-K1 cells; CCL61, American
Type Culture Collection, Rockville, MD, USA) stably expressing rat
dopamine D2(short) receptor and Ltk--fibroblast cells expressing D1
dopamine receptors were obtained from Professor K. Fuxe’s labora-
tory at the division of Cellular and Molecular Neurochemistry,
Department of Neuroscience, Karolinska Institute (Sweden), and
grown as described earlier.20 For experiments with D2 receptors
the CHO cells were collected, washed, and homogenized by sonica-
tion in incubation buffer (IB, 50 mM Tris–HCl, 120 mM NaCl,
5 mM KCl, 5 mM MgCl2, 1 mM EDTA, pH 7.4) and centrifuged at
30,000g for 20 min at 4 °C. The membrane pellets were washed
by re-homogenization in IB and centrifugation. The final pellets
were re-suspended in IB (2.5 Petri dishes with 95% confluency
per mL) and stored at ꢃ80 °C until use. For experiments with D1
receptors the Ltk--fibroblast cells were collected, washed and
homogenized by sonication in Tris–HCl buffer (TB, 50 mM Tris–
HCl, pH 7.4) and centrifuged at 30,000g for 40 min at 4 °C. The
membrane pellets were washed twice by re-homogenization in
TB and centrifugation. The final pellets were re-suspended in TB
(2 Petri dishes with 95% confluency per mL) and stored at ꢃ80 °C
until use.
Binding affinities of compounds to D2 dopamine receptors were
measured by incubation of 1.1 nM [3H]raclopride (74 Ci/mmol,
Perkin–Elmer Life Sciences) and appropriate concentrations of
compounds with membrane suspension of CHO cells for 90 min
at 25 °C.21 The reaction was stopped by filtration through GF/B fil-
ters using Brandel cell harvester and the filters were washed with
3 mL of ice-cold washing buffer (20 mM K-phosphate buffer,
100 mM NaCl, pH 7.4). Filters were incubated in scintillation cock-
tail OptiPhase HiSafe (Wallac PerkinElmer Life Sciences, Cam-
bridge, UK) overnight and the radioactivity content of filters was
measured by RackBeta 1219 liquid scintillation counter.
351 (100), 320 (39); HRMS (EI) m/z (%) calculated for
C25H26NO3þ: 388.1907 (M+ꢃCl), found: 388.1920 (M+ꢃCl, 67).
Anal. Calcd for C25H26ClNO3: C, 70.83; H, 6.18; N, 3.30. Found: C,
80.48; H, 6.41; N, 3.19; 1H NMR (400 MHz, DMSO-d6) d = 7.48
(1H, s, C1–H), 7.33–7.10 (3H, m, C2–Ar, C3–H), 6.91–6.82 (2H, m,
C2–Ar), 6.59–6.52 (2H, 2d, C8–H, C9–H, J8–9 8.0), 6.05 (3H, 3 br s,
0
C10–OH, C11–OH, C4 –OH), 4.12 (1H, dt, H6a, J6a–7a 4.1, J6a–7b 1.8),
3.37–2.40 (6H, m, H4a, H4b, H5a, H5b, H7a, H7b), 2.29 (2H, t, N–
CH2–CH2–CH3, J 4.4), 1.51 (2H, dt, N–CH2–CH2–CH3, J 4.5, J 1.7),
1.02 (3H, t, N–CH2–CH2–CH3, J 4.6); 13C NMR (100 MHz, DMSO-
d6) d = 157.23 (C4’–OH), 145.12 (C10), 144.69 (C11), 136.60–114.79
(Ar, 16C), 58.41 (C6), 53.55 (N–CH2–CH2–CH3), 49.29 (C5), 35.72
(C7), 29.19 (C4), 22.30 (N–CH2–CH2–CH3), 12.79 (N–CH2–CH2–CH3).
4.3. Route II
4.3.1. N-Demethylation of 2-bromoapocodeine (11)
Compound 11 (1.0 g, 2.92 mmol) and Na2WO4 (300 mg,
1.02 mmol) was dissolved in water:1,4-dioxane 1:2 (10 mL) and
cooled to 0 °C for the dropwise addition of H2O2 (30% w/v,
12 mmol). The reaction mixture was stirred at room temperature
for 3.5 h. The excess H2O2 was quenched by addition of small por-
tions of MnO2 at 0 °C and the presence of the peroxide determined
by KI-starch paper. The reaction mixture, containing some over-
oxidized product as dark precipitation, was then vacuum filtered
through a short pad of Celite. Solvent was removed in vacuo to give
crude product as a pale brown solid. It was immediately turned
into hydrochloride salt by dissolving in a few drops of chloroform
and dropping some ethanol saturated with HCl gas. After filtration,
the mixture of minor apocodeine.HCl and major apocodeine N-oxi-
deꢀHCl was dissolved in MeOH (10 mL) followed by the addition of
FeSO4ꢀ7H2O (2 equiv) at 0 °C. The reaction mixture was then left to
stir at room temperature for 1 h. Conversion was followed by TLC
(80% CH2Cl2/20% CH3OH). The reaction solvent was removed in
vacuo and the residue redissolved in a 0.1 M EDTA solution
adjusted to pH 10 by addition of ammonia (70 mL). The aqueous
phase was then extracted with CHCl3 (3 ꢁ 30 mL). The combined
organic phase was dried over MgSO4, filtered and the solvent
removed in vacuo to give dark brown mixture of the apocodeine
11 and the norapocodeine 12. 2-Bromonorapocodeine (12) was
isolated by means of silica column chromatography as an off-white
solid (554 mg, 55 %).
D2 receptor activation properties of compounds were measured
by incubating 0.2 nM [35S]GTP
cS with 10 lM GDP, appropriate
concentrations of compound and membrane suspension of CHO
cells for 90 min at 25 °C.19 The reactions were stopped and bound
radioactivity was determined as described above.
Binding affinities of compounds to D1 dopamine receptors were
measured by incubation of 2 nM [N-methyl-3H]R-(+)-7-chloro-8-
hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine
hydrochloride ([3H]SCH23390, 71 Ci/mmol, GE Life Sciences) with
appropriate concentrations of compounds in membrane suspen-
sion of Ltk--fibroblast cells in IB without sodium- and potassium
chloride for 60 min at 25 °C.22 The reactions were stopped and
bound radioactivity was determined as described above.
All pharmacological data were analyzed by means of non-linear
least squares regression analysis using the commercial program
GRAPHPAD PRISMTM 5.0 (GraphPad Software Inc.). Data are presented
as means SEM from at least two independent experiments car-
ried out in duplicates.
Mp: 146–148 °C; ½a D25
ꢃ 98 (c 0.1, chloroform); Rf (80% CH2Cl2/
ꢂ
20% CH3OH) 0.43; MS (EI): m/z (%) 345 (M+, 100), 330 (35), 309
(89); HRMS (EI) m/z (%) calculated for C17H16BrNO2þ: 345.0437
(M+), found: 345.0447 (M+, 100); dH (400 MHz CDCl3) 7.40 (1H, s,
C1–H), 7.18 (1H, s, C3–H), 6.54–6.48 (2H, 2d, C8–H, C9–H, J8–9
7.9), 6.05 (1H, br s, C11–OH), 4.06 (1H, dt, H6a, J6a–7a 4.7, J6a–7b
1.8), 3.81 (3H, s, O–CH3), 3.25–2.24 (7H, m, H4a, H4b, H5a, H5b,

4762
L. Herm et al. / Bioorg. Med. Chem. 17 (2009) 4756–4762
5. (a) Søndergaard, K.; Kristensen, J. L.; Palner, M.; Gillings, N.; Knudsen, G. M.;
Acknowledgments
Roth, B. L.; Begtrup, M. Org. Biomol. Chem. 2005, 3, 4077; (b) Sipos, A.; Berényi,
S.; Kiss, B.; Schmidt, É.; Greiner, I. Bioorg. Med. Chem. 2008, 16, 3773.
6. Casy, A. F.; Parfitt, R. T. Opioid Analgesics; Plenum: New York and London, 1986.
7. von Braun, J. Ber 1914, 47, 2312.
8. Brine, G. A.; Boldt, K. G.; Hart, C. K.; Caroll, F. I. Org. Prep. Proc. Int. 1976, 8, 103;
Borowitz, I. J.; Diakiw, V. J. Heterocycl. Chem. 1975, 12, 1123.
9. Diels, O.; Fischer, E. Ber. 1914, 47, 2043.
10. Speyer, E.; Rosenfeld, H. Ber. 1925, 58, 1125; Bertgen, C.; Fleischhacker, W.;
Vieböck, F. Ber. 1967, 100, 2992; Bertgen, C.; Fleischhacker, W.; Vieböck, F. Ber.
1967, 100, 3002; Hosztafi, S.; Makleit, S.; Bognár, R. Acta Chim. Acad. Sci. Hung.
1980, 103, 371.
The authors are grateful the financial supports to the Hungarian
National Science Foundation (Grant OTKA Reg. No. T049436,
PD77327 and NI61336), Estonian Science Foundation (Grant
6492) and Estonian Ministry of Education and Science (Project
0182734s06).
References and notes
11. Pohland, A.; Sullivan, H. R. (Eli Lilly Co.) NL Pat. 6515815, CA, 1966, 65, p 15441.
12. Søndergaard, K.; Kristensen, J. L.; Gillings, N.; Begtrup, M. Eur. J. Org. Chem.
2005, 4428.
13. Garrido, J. M. P. J.; Delerue-Matos, C.; Borges, F.; Macedo, T. R. A.; Oliveira-Brett,
A. M. J. Chem. Soc., Perkin Trans. 2 2002, 1713.
1. (a) Zhang, A.; Zhang, Y.; Branfman, A. R.; Baldesarini, R. J.; Neumeyer, J. L. J. Med.
Chem. 2007, 50, 171; Zhang, A.; Neumeyer, J. L.; Baldessarini, R. J. Chem. Rev.
2007, 107, 274; (b) Missale, C.; Nash, S. R.; Robinson, S. W.; Jaber, M.; Caron, M.
G. Physiol. Rev. 1998, 78, 189.
2. (a) Neumeyer, J. L.; Baldessarini, R. J.; Booth, R. G., 6th ed.. In Burger’s Medicinal
Chemistry and Drug Discovery; Abraham, D. J., Ed.; Springer: Berlin, 2003; Vol. 6,
pp 711–714, Chapter 12; (b) Sit, S. Y. Curr. Pharm. Des. 2000, 6, 1211; Poewe,
W.; Wenning, G. K. Mov. Disord. 2000, 15, 789; Martinez, R.; Puigvert, A.;
Pomerol, J. M.; Rodriguez-Villalba, R. J. Urol. 2003, 170, 2352; Perimenis, P.;
Gyftopoulos, K.; Giannitsas, K.; Markou, S. A.; Tsota, I.; Chrysanthopoulou, A.;
Athanasopoulos, A.; Barbalias, G. Int. J. Impot. Res. 2004, 16, 2.
14. Berényi, S.; Sipos, A.; Szabó, I.; Kálai, T. Synth. Commun. 2007, 37, 467; Sipos, A.;
Debreceni, Sz.; Szabó, R.; Gyulai, Zs.; Berényi, S. Synth. Commun. 2007, 37, 2549.
15. Berényi, S.; Makleit, S.; Szilágyi, L. Acta Chim. Hung. 1984, 117, 307.
16. Berényi, S.; Makleit, S.; Rantal, F. Acta Chim. Hung. 1985, 120, 201; Zhang, A.;
Csutorás, Cs.; Zong, R.; Neumeyer, J. L. Org. Lett. 2005, 7, 3239.
17. McCamley, K.; Ripper, J. A.; Singer, R. D.; Scammells, P. J. J. Org. Chem. 2003, 68,
9847.
3. (a) Gao, Y.; Baldessarini, R. J.; Kula, N. S.; Neumeyer, J. L. J. Med. Chem. 1990, 33,
1800; Berényi, S.; Csutorás, Cs.; Makleit, S.; Auth, F.; Laszlovszky, I.; Kiss, B.;
18. Sipos, A.; Berényi, S. Synlett 2008, 1703.
19. Terasmaa, A.; Finnman, U. B.; Owman, C.; Ferré, S.; Fuxe, K.; Rinken, A. Neurosci.
Lett. 2000, 280, 135.
}
Kárpáti, E.; Low, M. Med. Chem. Res. 1997, 7, 509; (b) Csutorás, Cs.; Zhang, A.;
Zhang, K.; Kula, N. S.; Baldessarini, R. J.; Neumeyer, J. L. Bioorg. Med. Chem. 2004,
12, 3553; Tóth, M.; Berényi, S.; Csutorás, Cs.; Kula, N. S.; Zhang, K.; Baldessarini,
R. J.; Neumeyer, J. L. Bioorg. Med. Chem. 2006, 14, 1918; Sipos, A.; Csutorás, Cs.;
Berényi, S.; Uustare, A.; Rinken, A. Bioorg. Med. Chem. 2008, 16, 4563.
4. (a) Gao, Y.; Ram, V. J.; Campbell, A.; Kula, N. S.; Baldessarini, R. J.; Neumeyer, J.
L. J. Med. Chem. 1990, 33, 39; (b) Creese, I.; Padgett, L.; Fazzini, E.; Lopez, F. Eur. J.
Pharmacol. 1979, 56, 411.
20. (a) Rinken, A.; Ferré, S.; Terasmaa, A.; Owman, C.; Fuxe, K. Neuroreport 1999, 10,
493; (b) Ferre, S.; Torvinen, M.; Antoniou, K.; Irenius, E.; Civelli, O.; Arenas, E.;
Fredholm, B. B.; Fuxe, K. J. Biol. Chem. 1998, 273, 4718; (c) Uustare, A.; Vonk, A.;
Terasmaa, A.; Fuxe, K.; Rinken, A. Life Sci. 2005, 76, 1513.
21. Harro, J.; Terasmaa, A.; Eller, M.; Rinken, A. Brain Res. 2003, 976, 209.
22. Uustare, A.; Reinart, R.; Rinken, A. Neurosci. Lett. 2006, 406, 169.