Structure-activity relationships for 1-alkyl-3-(1-naphthoyl)indoles at the cannabinoid CB1 and CB2 receptors: Steric and electronic effects of naphthoyl substituents. New highly selective CB2 receptor agonists

Article abstract of DOI:10.1016/j.bmc.2004.09.050

The synthesis and pharmacology of 47 1-alkyl-3-(1-naphthoyl)indoles (R = C₃H₇ and C₅H₁₁, R′ = H and CH₃) is described. Naphthoyl substituents include 4- and 7-alkyl groups, plus 2, 4, 6, and 7-methoxy groups. Three of these compounds are highly selective CB₂ receptor agonists. In an effort to improve indole-based CB₂ cannabinoid receptor ligands and also to develop SAR for both the CB₁ and CB₂ receptors, 47 indole derivatives were prepared and their CB₁ and CB₂ receptor affinities were determined. The indole derivatives include 1-propyl- and 1-pentyl-3-(1- naphthoyl)indoles both with and without a 2-methyl substituent. Naphthoyl substituents include 4- and 7-alkyl groups as well as 2-, 4-, 6-, 7-methoxy and 4-ethoxy groups. The effects of these substituents on receptor affinities are discussed and structure-activity relationships are presented. In the course of this work three new highly selective CB₂ receptor agonists were identified, 1-propyl-3-(4-methyl-1-naphthoylindole (JWH-120), 1-propyl-2-methyl-3-(6-methoxy-1-naphthoylindole (JWH-151), and 1-pentyl-3-(2-methoxy-1-naphthoylindole (JWH-267). GTPγS assays indicated that JWH-151 is a full agonist at CB₂, while JWH-120 and JWH-267 are partial agonists. Molecular modeling and receptor docking studies were carried out on a set of 3-(4-propyl-1-naphthoyl)indoles, a set of 3-(6-methoxy-1- naphthoyl)indoles and the pair of N-pentyl-3-(2-methoxy-1-naphthoyl)indoles. Docking studies indicated that the CB₁ receptor affinities of these compounds were consistent with their aromatic stacking interactions in the aromatic microdomain of the CB₁ receptor.

Full text of DOI:10.1016/j.bmc.2004.09.050

Bioorganic & Medicinal Chemistry 13 (2005) 89–112
Structure–activity relationships for
1-alkyl-3-(1-naphthoyl)indoles at the cannabinoid CB1 and CB2
receptors: steric and electronic effects of naphthoyl
substituents. New highly selective CB2 receptor agonists
John W. Huffman,a,* Gulay Zengin,a Ming-Jung Wu,a Jianzhong Lu,a George Hynd,a
Kristen Bushell,a Alicia L. S. Thompson,a Simon Bushell,a Cindy Tartal,b
Dow P. Hurst,b Patricia H. Reggio,b Dana E. Selley,c Michael P. Cassidy,c
Jenny L. Wileyc and Billy R. Martinc
aHoward L. Hunter Laboratory, Clemson University, Clemson, SC 29634-0973, USA
bDepartment of Chemistry and Biochemistry, Kennesaw State University, 1000 Chastain Road, Kennesaw, GA 30144, USA
cDepartment of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University,
Richmond, VA 23298-0613, USA
Received 21 July 2004; revised 28 September 2004; accepted 29 September 2004
Abstract—In an effort to improve indole-based CB2 cannabinoid receptor ligands and also to develop SAR for both the CB1 and
CB2 receptors, 47 indole derivatives were prepared and their CB1 and CB2 receptor affinities were determined. The indole derivatives
include 1-propyl- and 1-pentyl-3-(1-naphthoyl)indoles both with and without a 2-methyl substituent. Naphthoyl substituents include
4- and 7-alkyl groups as well as 2-, 4-, 6-, 7-methoxy and 4-ethoxy groups. The effects of these substituents on receptor affinities are
discussed and structure–activity relationships are presented. In the course of this work three new highly selective CB2 receptor agon-
ists were identified, 1-propyl-3-(4-methyl-1-naphthoylindole (JWH-120), 1-propyl-2-methyl-3-(6-methoxy-1-naphthoylindole (JWH-
151), and 1-pentyl-3-(2-methoxy-1-naphthoylindole (JWH-267). GTPcS assays indicated that JWH-151 is a full agonist at CB2,
while JWH-120 and JWH-267 are partial agonists. Molecular modeling and receptor docking studies were carried out on a set
of 3-(4-propyl-1-naphthoyl)indoles, a set of 3-(6-methoxy-1-naphthoyl)indoles and the pair of N-pentyl-3-(2-methoxy-1-naph-
thoyl)indoles. Docking studies indicated that the CB1 receptor affinities of these compounds were consistent with their aromatic
stacking interactions in the aromatic microdomain of the CB1 receptor.
ꢀ 2004 Elsevier Ltd. All rights reserved.
1. Introduction
which CP-55,940 (2, DMH = 1,1-dimethylheptyl) is the
prototypical example.7,8
Nearly 40 years ago Gaoni and Mechoulam reported the
elucidation of the structure of D9-tetrahydrocannabinol
(1, THC) the principal psychoactive compound present
in marijuana.1 Subsequently, a comprehensive set of
structure–activity relationships (SAR) was developed
based on the dibenzopyran nucleus of THC.2–6 These
SAR were later extended to the very potent group of
non-traditional cannabinoids developed by Pfizer, of
These pharmacological effects of cannabinoids are con-
sidered to be mediated through at least two G-protein-
coupled, transmembrane receptors. One of these, desig-
nated as CB1, is found predominantly in the central
nervous system and is thought to be responsible for
most of the overt pharmacological effects of cannabi-
noids.5,9–11 A second receptor, designated CB2, was
originally identified from macrophages present in the
spleen, and is expressed primarily in the periphery.12
Evidence has been presented recently for the existence
of a third cannabinoid receptor, which has been detected
in mouse brain.13
Keywords: Cannabinoids; Structure–activity relationships; Cannabi-
noid receptors; Aminoalkylindole.
*
Corresponding author. Tel.: +1 8646563133; fax: +1 8646566613;
e-mail: huffman@clemson.edu
0968-0896/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2004.09.050

90
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
Some years ago in the course of a program directed to-
ward the development of non-steroidal anti-inflamma-
tory drugs, a group at Sterling–Winthrop reported that
pravadoline (3), an indole derivative, unexpectedly inhib-
ited contractions of the electrically stimulated mouse vas
deferens.14 Later work revealed that 3, and a number of
related compounds also inhibit adenylate cyclase, are
antinociceptive and interact with a G-coupled protein
in the brain. Subsequent work indicated that the G-cou-
pled protein is the cannabinoid CB1 receptor and that
these aminoalkylindoles exhibit typical cannabinoid
pharmacology in vivo.15,16 One of the aminoalkylin-
doles, WIN-55,212-2 (4), developed by the Winthrop
group is not only potent in vivo, but has high affinity
for both the cannabinoid CB1 and CB2 receptors.17
be replaced by an alkyl group to provide relatively sim-
ple indole derivatives, which exhibit typical cannabinoid
pharmacology.19,20 In particular, JWH-007, 1-pentyl-2-
methyl-3-(1-naphthoyl)indole (5) has high affinity for
the CB1 receptor and exhibits typical cannabinoid phar-
macology in vivo. The 1-propyl analog of 5, JWH-015
(6) has relatively high affinity for the CB2 receptor,
and weak affinity for the CB1 receptor.17
In an effort to develop improved indole-based CB2 cann-
abinoid receptor ligands and also to develop SAR for
both the CB1 and CB2 receptors a number of additional
indole derivatives were prepared and their pharmacol-
ogy was evaluated.21,22 It was found that CB1 receptor
affinity is optimal with a n-pentyl nitrogen substituent,
and decreases dramatically with N-alkyl substituents of
three or less carbon atoms. CB1 receptor affinity is also
greatly attenuated with N-alkyl substituents longer than
six carbon atoms. A 2-methyl substituent slightly de-
creases affinity at the CB1 receptor and a 4-methoxy-1-
naphthoyl group at C-3 of the indole, as in JWH-098
(7) enhances CB1 receptor affinity. A 7-methyl-1-naph-
thoyl substituent in JWH-046 (8) and JWH-048 (9) has
relatively little effect on either CB1 or CB2 receptor affin-
ity. The SAR at the CB2 receptor are somewhat similar
to those at the CB1 receptor, however there are a num-
ber of exceptions to these generalizations, which render
it difficult to establish comprehensive SAR for these
compounds at the CB2 receptor.21,23
During the course of their investigations of the aminoalk-
ylindoles, the Winthrop group synthesized more than 100
compounds and developed some preliminary SAR.14,15,18
These included the observation that a group larger than
methyl at C-2 of the indole nucleus greatly attenuates po-
tency and that a bicyclic aroyl group, usually 1-naphthoyl
or a substituted 1-naphthoyl group, at C-3 is essential for
potency. It was further concluded that an aminoalkyl
group, usually substituted aminoethyl, attached to the
indole nitrogen was essential for cannabinoid activity.
Subsequent studies by our group established that the
aminoalkyl group appended to the indole nitrogen could
The SAR outlined above includes only indoles with an
unsubstituted 3-naphthoyl substituent, or with 4-meth-
oxy- or 7-methyl-1-naphthoyl groups. To further devel-
op SAR for these compounds, and with the goal of
preparing CB2 selective ligands, a number of additional
cannabimimetic indoles have been prepared and their
affinities for the CB1 and CB2 receptors have been
determined. These compounds include N-propyl- and
N-pentyl-3-(1-naphthoyl)indoles in which the napht-
hoyl group contains various alkyl and alkoxy substitu-
ents, and the indole is either unsubstituted at C-2 or
contains a 2-methyl group. The choice of the N-propyl
substituent is based on the observation that the two
most highly CB2 selective indole derivatives prepared
in our laboratory, JWH-015 (6) and JWH-046 (8) both
contain this substitution pattern.21,23 The N-pentyl
group was chosen since this substituent almost invaria-
bly provides compounds with higher CB1 receptor
affinities than are observed with other nitrogen
substituents.
CH
OH
3
OH
OH
H C
3
O
C H
DMH
5
11
H C
3
HO
1
2 DMH = 1,1-dimethylheptyl
O
O
H CO
3
H C
N
H C
N
3
3
O
N
O
N
O
3
4
R''
2. Results
O
To explore the steric and electronic effects of various
naphthoyl substituents, 3-(4-alkyl-1-naphthoyl), 3-(7-
ethyl-1-naphthoyl), 3-(2-, 6-, 7-methoxy-1-naphthoyl),
3-(4-ethoxy-1-naphthoyl)indoles (for numbering see the
structure included in Table 1), have been synthesized
and their CB1 and CB2 receptor affinities have been
determined. These indoles were prepared by modifica-
tions of established routes, either by coupling substi-
tuted 1-naphthoyl chlorides with 1-alkyl- or 1-alkyl-2-
R'
H C
N
R
3
5 R = C H , R', R'' = H
5
11
6 R = C H , R', R'' = H
3
7
7 R = C H , R' = OCH , R'' = H
5
11
3
8 R = C H , R' = H, R'' = CH
3
7
3
9 R = C H , R' = H, R'' = CH
5
11
3

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
91
Table 1. Structures, method of synthesis, and receptor affinities (mean SEM) of 3-(alkyl-1-naphthoyl)indoles
R'''
7
6
O
3
2
R''
R'
N
R
4
2
1
Compound
Ki (nM)
g
Synthesis
R
R0
R00
R000
CB1
41 2a
CB2
36 10b
Ratio CB2/CB1
D9-THC (1)
WIN-55,212-2 (4)
JWH-072c
JWH-015c,d (6)
JWH-018c
JWH-007c,d (5)
JWH-120 (41)
JWH-148
1.1
6.8
6.2
11.9
3.3
3.3
173
8.8
0.6
6.8
3.3
5.8
0.67
3.6
2.7
4.3
0.6
2.1
6.6
3.0
1.9
6.5
2.0
21
1.9 0.1b
1050 55c
164 22c
0.28 0.16b
170 54c
13.8 4.6b
2.9 2.6c
2.9 2.6c
6.1 0.7
14 1.0
C3H7
C3H7
C5H11
C5H11
C3H7
C3H7
C5H11
C5H11
C3H7
C3H7
C5H11
C5H11
C3H7
C3H7
C5H11
C5H11
C3H7
C3H7
C5H11
C5H11
C3H7
C3H7
C5H11
C3H7
C3H7
C5H11
C5H11
H
H
H
H
H
H
CH3
H
H
H
9
5c
CH3
H
H
9.5 4.5c
1054 31
B
CH3
CH3
CH3
CH3
C2H5
C2H5
C2H5
C2H5
C3H7
C3H7
C3H7
C3H7
C4H9
C4H9
C4H9
C4H9
H
H
A
CH3
H
H
123
8
JWH-122e
JWH-149e
JWH-212
H
0.69 0.5e
5.0 2.1e
33 0.9
1.2 1.2
0.73 0.03
10 1.2
CH3
H
H
C
C
C
C
C
C
C
C
C
C
C
C
A
H
JWH-211
JWH-210
CH3
H
H
70 0.8
0.46 0.03
1.5 0.2
12 0.8
H
0.69 0.01
0.42 0.05
9.6 2.0
12 0.8
JWH-213
JWH-180
CH3
H
H
H
26
52
2
2
JWH-189
JWH-182
CH3
H
H
H
0.65 0.03
1.3 0.1
342 20
147 20
1.1 0.1
0.62 0.04
JWH-181
JWH-239
CH3
H
H
H
52
49
6
7
JWH-241
JWH-240
JWH-242
CH3
H
H
H
14
42
1
9
7.2 1.3
6.5 0.3
106 46
16 5f
0.49 0.1f
123 34
240 63
3.8 0.6
5.6 0.7
CH3
H
H
JWH-076
CH3
CH3
CH3
C2H5
C2H5
C2H5
C2H5
214 11
343 38f
10.7 1.0f
338 34
JWH-046f (8)
JWH-048f (9)
JWH-235
CH3
CH3
H
H
H
22
B
B
B
B
H
2.7
5.6
2.2
5.0
JWH-236
JWH-234
JWH-262
CH3
H
H
1351 204
8.4 1.8
H
CH3
H
28
3
a Ref. 41.
b Ref. 17.
c Refs. 20,21.
d Ref. 19.
e Ref. 24.
f Ref. 21.
g Ratio is based on interspecies comparison of rat CB1 and human CB2.
methylindoles or by acylation of indole or 2-methylin-
dole, followed by N-alkylation (Scheme 1).14,15,18,19,24
cal reaction gave satisfactory to good yields. The meth-
od of choice is that reported recently by Okauchi et al.
(method B) in which N-alkylindoles 12 are treated with
dimethyl- or diethylaluminum chloride for 30min prior
to the addition of the aroyl halide.25 This mild proce-
dure provides pure products (13) in yields of 50–90%.
The final methods are variations of a classical Friedel–
Crafts procedure, but use ethylaluminum dichloride at
ambient temperature for either four days (method C)
or for 18h (method D). The yields for procedures C
and D are adequate, but are somewhat inferior to those
using OkauchiÕs method (procedure B).
In our early work, indole (10, R = H) or 2-methylindole
(10, R = CH3) was treated with methylmagnesium bro-
mide to give the ambident indolyl anion, which upon
reaction with an aroyl chloride gave the 3-acylindole
(11, method A).19 N-Alkylation with the appropriate
primary alkyl bromide using KOH in DMSO provides
the N-alkyl-3-aroylindole. Although this sequence was
satisfactory when using readily available aroyl halides,
the yields in the first step were variable, the 3-aroylin-
doles (11) were difficult to purify and alternative meth-
odology was explored. Traditional aluminum chloride
catalyzed Friedel–Crafts acylation of N-alkylindoles
gave poor yields, however three variations of this classi-
Of the 1-naphthoic acids required for the synthesis
of the cannabimimetic 3-(4-alkyl-1-naphthoyl)indoles,
only 4-methyl-1-naphthoic acid (14, Scheme 2) is

92
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
14–17 to the 3-(4-ethyl-1-naphthoyl)indoles (JWH-210–
O
JWH-213), the 3-(4-propyl-1-naphthoyl)indoles (JWH-
180–JWH-182, JWH-189) and the 3-(4-butyl-1-naph-
thoyl)indoles (JWH-239–JWH-242) was carried out
using method C. The CB1 and CB2 receptor affinities
of these compounds are summarized in Table 1.
Ar
a
R
N
R
N
H
H
10
11
b
7-Methyl-1-naphthoic acid (20), which had been used
previously for the synthesis of JWH-046 (8) and JWH-
048 (9),21 was prepared by a modification of the method
of Snatzke and Kunde (Scheme 3).30 Friedel–Crafts
acylation of 2-methylnaphthalene (21) under standard
conditions using acetyl chloride and AlCl3 proceeds as
described to provide 1-acetyl-7-methylnaphthalene
(22), however, conversion to acid 20 could not be ef-
fected using the haloform reaction under various condi-
tions. In the King modification of the haloform reaction,
ketone 22 with iodine and pyridine gave pyridinium io-
dide 23, which upon basic hydrolysis and acidification
provided acid 20.31 Conversion of this acid to 1-pro-
pyl-3-(7-methyl-1-naphthoyl)indole was carried out by
method A. 7-Ethyl-1-naphthoic acid (24), which was
employed for the synthesis of the 3-(7-ethyl-1-naph-
thoyl)indoles was prepared from 2-ethylnaphthalene
(25) in an analogous manner through ketone 26 and
pyridinium iodide 27. Conversion of 7-ethyl-1-naph-
thoic acids to the 3-(7-ethyl-1-naphthoyl)indoles
(JWH-234–JWH-236, JWH-262) was carried out using
method B. The receptor affinities for the 3-(7-alkyl-1-
naphthoyl)indoles are included in Table 1.
O
R
Ar
c
R
N
N
R'
R'
12
13
Scheme 1. Reagents and conditions: (a) MeMgBr, Et2O/THF, 0ꢁC,
then ArCOCl, reflux; (b) R0Br, KOH, DMSO; 80ꢁC; (c) ArCOCl,
Lewis acid (see text and Experimental).
O
N(Ph)
2
CO H
2
a
b
R
R
R
18
19
14 R = CH
3
15 R = C H
2
3
4
5
7
9
16 R = C H
In the methoxynaphthoyl series, the 2-, 4-, 6-, and 7-
methoxy-1-naphthoylindoles were prepared and their
affinities for the CB1 and CB2 receptors were determined
(Table 2). In addition, to evaluate steric and electronic
effects upon receptor affinities, the 4-ethoxy analogs
17 R = C H
28 R = OC H
2
5
Scheme 2. Reagents and conditions: (a) Ph2NCOCl, AlCl3,
ClCH2CH2Cl, reflux; (b) KOH, diethylene glycol, reflux, then HCl.
were
also
prepared.
The
3-(4-ethoxy-1-naph-
thoyl)indoles were prepared from 4-ethoxy-1-naphthoic
acid (28, Scheme 2), which was obtained from 1-ethoxy-
naphthalene by the procedure outlined in Scheme 2.
commercially available. 4-Ethyl- (15), 4-propyl- (16) and
4-but- yl-1-naphthoic (17) acids were reported some
years ago by Russian workers, who prepared them by
chloromethylation of the 1-alkylnaphthalene, followed
by conversion to the corresponding acetate, hydrolysis
to the alcohol, and oxidation to the carboxylic acid.26
COCH
3
R
R
a
b
A
considerably more efficient approach employs
Friedel–Crafts acylation of the appropriate 1-alkylnaph-
thalene (18, R = C2H5, C3H7, C4H9) with N,N-diphenyl-
carbamyl chloride to give 1-naphthyl N,N-diphen-
ylamides (19, R = C2H5, C3H7, C4H9), hydrolysis of
which will afford the corresponding carboxylic acid.27
Although the acylation step proceeded smoothly in
yields of 80–85%, hydrolysis could not be effected using
the reported procedure, ethanolic sodium hydroxide at
reflux. The amides were successfully hydrolyzed in
90–92% yield by treatment with potassium hydroxide in
diethylene glycol at reflux.28,29 Acidification then affords
the 4-alkyl-1-naphthoic acids (14–17). Conversion of
4-methyl-1-naphthoic acid to 1-propyl-3-(4-methyl-1-
naphthoyl)indole (JWH-120) and 2-methyl-1-propyl-3-
(4-methyl-1-naphthoyl)indole (JWH-148) was carried
out using methods B and A, respectively. The 1-pentyl
analogs of these compounds (JWH-122, JWH-149) have
been reported previously.24 The conversion of acids
21 R = CH
22 R = CH
3
3
25 R = C H
26 R = C H
2
5
2
5
+
-
COCH N
CO H
2
2
I
R
R
c
23 R = CH
20 R = CH
3
24 R = C H
3
5
27 R = C H
2
2 5
Scheme 3. Reagents and conditions: (a) CH3COCl, AlCl3,
ClCH2CH2Cl, rt; (b) I2, pyridine, 100 ꢁC; (c) NaOH/H2O, reflux, then
HCl.

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
93
and their affinities for the CB1 and CB2 receptors are
also included in Table 2.21,24
O
O
CO2H
OCH3
H3C
H3C
For the synthesis of the 3-(2-methoxy-1-naph-
thoyl)indoles 2-methoxy-1-naphthoic acid (29) was re-
quired. Acid 29 is readily available by methylation of
commercially available 2-hydroxy-1-naphthoic acid fol-
lowed by hydrolysis32 and was converted to indoles
30–33 (JWH-265–JWH-268, Table 2) by method B. In-
doles 30 (JWH-265) and 32 (JWH-267), which are
unsubstituted at C-2 of the indole nucleus showed nor-
mal 1H and 13C NMR spectra, however in the 1H spectra
of the 2-methyl analogs (31, JWH-266, and 33, JWH-
268) the signal at d 2.50 due to the indole 2-methyl
group and an aromatic proton at d 6.95 appeared as
very broad singlets. A second aromatic proton at d
7.13 gave rise to a somewhat broadened singlet, rather
than the sharp signals characteristic of the naphthoylin-
doles. Also, the signals due to the 2-methyl group
and one aromatic carbon were missing in the 13C spectra
of indoles 31 and 33. Although it was possible that these
compounds did not have the correct structures, both
N
OCH3
R'
N
R
N
O
29
30 R = C3H7, R' = H
31 R = C3H7, R' = CH3
32 R = C5H11, R' = H
33 R = C5H11, R' = CH3
34
Acid 28 was converted to the 3-(4-ethoxy-1-naph-
thoyl)indoles (JWH-258–JWH-261) by method B and
their receptor affinities are included in Table 2. The 3-
(4-methoxy-1-naphthoyl)indoles (JWH-079, JWH-094,
JWH-081, JWH-098) have been reported previously
Table 2. Structures, method of synthesis, and receptor affinities (mean SEM) of 3-(alkoxy-1-naphthoyl)indoles
""R
R'''''
R'''
O
R''
R'
N
R
Compound
Ki (nM)
Synthesis
R
R0
H
R00
R000
R0000
R0000 0
CB1
CB2
36 10b
Ratio CB2/CBe
D9-THC (1)
WIN-55,212-2 (4)
JWH-265 (30)
JWH-266 (31)
JWH-267 (32)
JWH-268 (33)
JWH-079c
41 2a
1.1
6.8
1.9 0.1b
0.28 0.16b
80 13
B
B
B
B
C3H7
C3H7
C5H11
OCH3
H
H
H
3788 323
>10,000
47
CH3 OCH3
OCH3
H
H
H
455 55
7.2 0.14
40 0.6
32 6c
>22
53
H
H
H
H
381 16
1379 193
63 3c
476 67c
C5H11 CH3 OCH3
H
H
H
34
C3H7
C3H7
C5H11
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
OCH3
OCH3
OCH3
OCH3
OC2H5
OC2H5
OC2H5
OC2H5
H
H
H
2.0
4.9
JWH-094c
CH3
H
H
H
97 3c
JWH-081c,d
JWH-098c,d
JWH-259
H
H
1.2 0.03c,d 12.4 2.2c
0.1
2.4
C5H11 CH3
H
H
4.5 0.1c,d
220 29
1.9 0.3c
74
lMB
B
C3H7
C3H7
C5H11
H
H
H
7
3.0
3.5
JWH-261
JWH-258
CH3
H
H
H
767 105
4.6 0.6
29 0.4
221 14
10.5 1.3
25 1.9
138 12
30 1.1
1.9 0.08
11 0.5
B
H
H
0. 44
1. 2
17
JWH-260
JWH-163
B
C5H11 CH3
H
H
D
D
D
D
D
D
D
D
C3H7
C3H7
C5H11
H
OCH3
OCH3
OCH3
OCH3
H
H
2358 215
JWH-151 (42)
JWH-166
JWH-153
CH3
H
H
H
>10,000
>333
23
23
H
H
44 10
250 24
204 26
1568 201
6.6 0.7
C5H11 CH3
H
H
JWH-165
JWH-160
C3H7
C3H7
C5H11
H
H
OCH3
OCH3
OCH3
OCH3
71
8
2.9
3.6
CH3
H
H
H
441 110
6.9 0.2
10.4 1.4
JWH-164
JWH-159
H
H
0.96
4.3
C5H11 CH3
H
H
45
1
a Ref. 41.
b Ref. 17.
c Ref. 21.
d Ref. 24.
e Ratio is based on interspecies comparison of rat CB1 and human CB2.

94
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
had low and high resolution mass spectra consistent
with the assigned molecular formulas. The structure of
1-propyl-2-methyl-3-(2-methoxy-1-naphthoyl)indole (31)
was confirmed by X-ray crystallography.33
OH
O
R'
R'
a, b
R
R
It appeared probable that the anomalous NMR spectra
were due to restricted rotation about the bond between
C-3 of the indole nucleus and/or the naphthalene C-1
bond and the carbonyl carbon atom. Accordingly, a var-
iable temperature study of the 1H NMR spectrum of in-
dole 31 was carried out. There was little change in the
1H spectrum at 50ꢁC, but at 75ꢁC the signal for the
C-2 methyl group had sharpened somewhat, as had that
of the aromatic proton at d 6.95, and the signal at d 7.13
was resolved to a broadened triplet, J = 8.2Hz. At
125ꢁC the C-2 methyl signal was a rather sharp singlet
at d 2.46, the aromatic proton at d 6.95 had become a
well-defined triplet, J = 7.8Hz, and the triplet at d 7.13
appeared as a triplet of doublets, J = 0.5 and 8.2Hz.
The 1H spectrum at 100ꢁC was slightly less well resolved
than that at 125ꢁC.
37 R = OCH3, R' = H
38 R = H, R' = OCH3
39 R = OCH3, R' = H
40 R = H, R' = OCH3
CO2H
R'
c, d
R
35 R = OCH3, R' = H
36 R = H, R' = OCH3
Scheme 4. Reagents and conditions: (a) Br2, CCl4, Et2O, HCl, 0–5ꢁC;
(b) LiBr, LiCO3, DMF, reflux; (c) Tf2O, pyridine, 0ꢁC–rt; (d)
Pd(OAc)2, 1,3-diphenylphosphinopropane, Et3N, HCO2H, DMF,
CO, rt.
A COSY spectrum of the aromatic region of indole 31
revealed that the protons, which give rise to the triplets
at d 6.95 and d 7.13 are coupled to each other and each is
coupled to one additional proton within the complex
pattern between d 7.3 and d 7.6. The triplets at d 6.95
and d 7.13 can only arise from the 5,6-protons on the in-
dole nucleus or the 6,7-naphthalene protons. Since the
aromatic protons of a simple acyl indole derivative, 2-
methyl-1-morpholinoethyl-3-acetylindole (34) appear
as a series of multiplets between d 7.26 and d 7.97,34
the triplets at d 6.95 and d 7.13 in indole 31 must arise
from the protons at C-6 and C-7 of the naphthalene.
These data confirm that the anomalies in the NMR
spectra of indoles 31 and 33 are the result of restricted
rotation about the bond between C-3 of the indole nu-
cleus and/or the naphthalene C-1 bond and the carbonyl
carbon atom. The energy barrier to rotation was deter-
mined using variable temperature 1H NMR, and the
coalescence temperature was found to be 0ꢁC. The free
energy of activation was calculated from the stopped ex-
change limit at ꢀ50ꢁC and the coalescence temperature
to give a rotational barrier of 13.1kcal/mol.35 An AM1
coordinate drive study shows that during rotation about
the naphthalene C-1 bond and the carbonyl carbon
atom the oxygen of the methoxy group has close Van
der WaalsÕ contacts with C-2 and C-3 of the indole.
The maximum overlap occurs at a carbonyl oxygen–car-
bonyl carbon–indole C-3–indole C-2 torsion angle of
ꢀ89.8ꢁ. The calculated energy difference between the
global minimum energy conformer and this conforma-
tion is 9.38kcal/mol. Single point energy calculations
for the difference in energy between the global minimum
energy conformer and the conformation for which max-
imum overlap occurs was found to be 12.86kcal/mol at
the HF 3-21G* level. The receptor affinities of the 3-(2-
methoxy-1-naphthoyl)indoles (JWH-265–JWH-268) are
included in Table 2.
years ago using classical chemistry. The 6-methoxy acid
(35) was originally synthesized by Price et al. in 12%
yield by the aluminum chloride catalyzed reaction of
furoic acid and anisole.36 7-Methoxy-1-naphthoic acid
(36) was described by Fieser and Holmes who prepared
it from ethyl 4-(4-methoxyphenyl)butanoate via 7-meth-
oxy-3,4-dihydro-1-naphthoic acid.37 The dihydro acid
was synthesized in 51% overall yield, however no yield
was specified for the dehydrogenation to acid 36. A sub-
sequent synthesis of acid 36 utilized the reaction of 2-
methoxynaphthalene with an oxalyl chloride equivalent
to give a methoxyacenapthenquinone, which was con-
verted to acid 36 in two steps and good yield.38 In our
hands attempted repetition of the reaction of 2-meth-
oxynaphthalene with the oxalyl chloride surrogate
failed. Other published syntheses of both acids did not
appear attractive and alternative methods of synthesis
were explored.
Both 6- (37) and 7-methoxy-1-tetralone (38, Scheme 4)
are commercially available, and appeared to be suitable
starting materials for the synthesis of acids 35 and 36.
The initial synthetic route to 6-methoxy-1-naphthoic
acid (35) entailed conversion of tetralone 37 to the enol
triflate, followed by palladium mediated carbonylation
to 6-methoxy-3,4-dihydro-1-naphthoic acid.39 Dehydro-
genation to acid 35 did not proceed to completion and
the mixture of 35 and the dihydro acid proved exceed-
ingly difficult to separate. The conversion of tetralones
37 and 38 to 6- (39) and 7-methoxy-1-naphthol (40),
respectively, was reported some years ago by Shand
and Thompson who accomplished this transformation
by dehydrogenation using sulfur at 250ꢁC.40 As an alter-
native to thermal dehydrogenation, ketones 37 and 38
were converted to the corresponding a-bromo ketones,
dehydrohalogenation of which provided phenols 39
and 40.41 Conversion of these phenols to the corre-
sponding triflates followed by palladium mediated
carbonylation gave acids 35 and 36 in good yield.
Acid 35 was converted to the 3-(6-methoxy-1-
naphthoyl)indoles (JWH-151, JWH-153, JWH-163,
The 6- and 7-methoxy-1-naphthoylindoles required 6-
(35, Scheme 4) and 7-methoxy-1-naphthoic acid (36),
respectively, both of which were prepared a number of

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
95
JWH-166) and acid 36 was converted to the 3-(7-meth-
oxy-1-naphthoyl)indoles (JWH-159, JWH-160, JWH-
164, JWH-165) by method D. The receptor affinities
for these 3-(6- and 7-methoxy-1-naphthoyl)indoles are
included in Table 2.
the CB1 receptor affinities of the 1-pentyl-3-(4-butyl-1-
naphthoyl)indoles are much higher than those of the
1-propyl compounds. 1-Pentyl-3-(4-butyl-1-naphthoyl)-
indole, JWH-240 has Ki = 14 1nM and the
2-methylindole analog, JWH-242, has Ki = 42 9nM.
Again, the values for the CB2 receptor affinities of the
4-butyl-1-naphthoylindoles are not nearly as diverse as
the CB1 affinities. The 1-propyl analogs, JWH-239 and
JWH-241 have Ki = 52 6 and 49 7nM, respectively.
The CB2 receptor affinities for the 1-pentyl compounds,
JWH-240 and JWH-242 are essentially identical with
Ki = 7.2 13nM for JWH-240 and Ki = 6.5 0.3nM
for JWH-242.
The affinities of the alkylnaphthoyl and alkoxynaphtho-
ylindoles for the CB1 receptor were determined by meas-
uring their ability to displace the potent cannabinoid
[3H] CP-55,940 (2) from its binding site in a membrane
preparation from rat brain as described by Compton
et al.42 Affinities for the CB2 receptor were determined
by measuring the ability of the compounds to displace
[3H] CP-55,940 from a cloned human receptor prepara-
tion using the procedure described by Showalter et al.17
The results of these determinations are summarized in
Tables 1 and 2. Also included in Tables 1 and 2 are
the receptor affinities for D9-THC (1) and WIN-
55,212-2 (4).
We had previously reported the CB1 and CB2 receptor
affinities of 2-methyl-1-propyl-3-(7-methyl-1-napht-
hoyl)indole (8), JWH-046 with Ki = 343 38nM at
CB1 and Ki = 16 5nM at CB2 (Table 1), which is com-
parable in its affinity for both receptors and in CB2
selectivity to JWH-015 (6).21 JWH-076, the analog of
JWH-046 lacking the 2-methyl group, has slightly great-
er affinity for the CB1 receptor than JWH-046
(Ki = 214 11nM), but considerably less affinity for
the CB2 receptor (Ki = 106 46nM). 2-Methyl-1-pen-
tyl-3-(7-methyl-1-naphthoyl)indole (9, JWH-048) was
reported previously and has Ki = 10.7 1nM for the
CB1 receptor and Ki = 0.49 0.1nM for the CB2 recep-
tor.21 These values are very similar to those of the ana-
log without the 7-methyl group, JWH-007 (5), which
has Ki = 9.5 4.5nM at the CB1 receptor and
Ki = 2.9 2.6nM at the CB2 receptor.19–21
In the 4-alkyl-1-naphthoyl series (Table 1), the 4-methyl-
1-propyl compounds, JWH-120 (41) and JWH-148,
have very slight (Ki = 1054 31nM) and modest
(Ki = 123 8nM) affinities, respectively, for the CB1
receptor. This pair of compounds is unusual in that
the analog with an indole 2-methyl group (JWH-148)
has significantly greater affinity for the CB1 receptor
than the unsubstituted compound (JWH-120). The
CB2 receptor affinities of these compounds are similar,
for JWH-120 Ki = 6.1 7nM, and for JWH-148
Ki = 14 1.0nM. The 4-methyl-1-pentyl analogs,
JWH-122 and JWH-149 have high affinities for both
the CB1 and CB2 receptors. In particular, JWH-122,
the compound lacking the indole C-2 methyl group,
has subnanomolar affinity for the CB1 receptor
(Ki = 0.69 0.5nM).24
For the 1-propyl-3-(7-ethyl-1-naphthoyl)indoles (Table
1), the 2-methyl compound, JWH-236 has considerably
lower affinity than its 7-methyl homologue for both
the CB1 and CB2 receptors with Ki = 1351 204nM at
CB1 and Ki = 240 63nM at CB2. The analog lacking
the 2-methyl group, JWH-235 has receptor affinities
very similar to those of the corresponding 7-methyl
compound, with Ki = 338 34nM at CB1 and Ki =
123 34nM at CB2. As expected the 1-pentyl com-
pounds both have considerably greater affinities for
both receptors than the 1-propyl analogs. For 1-pen-
tyl-3-(7-ethyl-1-naphthoyl)indole, JWH-234, Ki = 8.4
1.8nM at CB1 and Ki = 3.8 0.6nM at CB2. The 2-
methyl analog has slightly less affinity for both receptors
with Ki = 28 3nM at CB1 and Ki = 5.6 0.7nM at
CB2.
The 4-ethyl- and 4-propyl -1-naphthoylindoles (Table 1)
all have uniformly high affinities for both receptors. Fol-
lowing the usual trend for CB1 receptor affinities the 1-
propyl compounds have lower affinities than the 1-pen-
tyl analogs, and the compounds with an indole 2-methyl
group have somewhat lower affinities than the unsubsti-
tuted analogs. The CB1 receptor affinities for these
compounds range from Ki = 0.46 0.03nM for
1-pentyl-3-(4-ethyl-1-naphthoyl)indole, JWH-210, to
Ki = 70 0.8nM for 2-methyl-1-propyl-3-(4-ethyl-1-
naphthoyl)indole, JWH-211. The CB1 receptor affinities
for the 3-(4-propyl-1-naphthoyl)indoles are comparable
to those of the 4-ethyl analogs. The CB2 receptor affin-
ities for these eight 4-propyl and 4-ethyl compounds fall
within a narrow range, from Ki = 0.62 0.04 for 2-
methyl-1-pentyl-3-(4-propyl-1-naphthoyl)indole, JWH-
181, to Ki = 12 0.8 for 2-methyl-1-propyl-3-(4-ethyl-
1-naphthoyl)indole, JWH-211.
In the 3-(4-methoxy-1-naphthoyl)indole series (Table 2)
the receptor affinities of all four of the 1-propyl- and 1-
pentyl-3-(4-methoxy-1-naphthoyl)indoles have been re-
ported previously.21,24 The 1-propyl-2-methyl analog
(JWH-094) has little affinity for the CB1 receptor with
Ki = 476 67nM, and only modest affinity for the CB2
receptor (Ki = 97 3nM). However, JWH-079, 1-pro-
pyl-3-(4-methoxy-1-naphthoyl)indole has Ki = 63
3nM at CB1 and good affinity for the CB2 receptor
(Ki = 32 6nM). As expected the 1-pentyl analogs
have considerably higher affinity for both receptors. 1-
The 4-butyl-1-naphthoylindoles (Table 1) have signifi-
cantly lower affinities for the CB1 receptor than the 4-
ethyl and 4-propyl-1-naphthoylindoles. In particular,
the affinities of 1-propyl-3-(4-butyl-1-naphthoyl)indole,
JWH-239 (Ki = 342 20nM) and its 2-methylindole
analog, JWH-241 (Ki = 147 20nM) are significantly
lower than the ethyl and propyl analogs. Predictably,
Pentyl-3-(4-methoxy-1-naphthoyl)indole (JWH-081)
has very high affinity for the CB1 receptor (Ki =
1.2 0.03nM) and high affinity for the CB2 receptor

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J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
(Ki = 12.4 2.2nM). The 2-methyl analog (JWH-098, 7)
has slightly lower affinity for the CB1 receptor with
Ki = 4.5 0.1nM and somewhat higher affinity for the
CB2 receptor (Ki = 1.9 0.3nM).
Ki = 11 1nM and Ki = 1.9 0.1nM, respectively. 1-
Propyl-3-(6-methoxy-1-naphthoyl)indole (JWH-163)
has Ki = 138 12nM at CB2, while the 2-methyl com-
pound (JWH-151, 42) has significant affinity for the
CB2 receptor, Ki = 30 1nM. JWH-151 is a highly
selective (>333-fold) ligand for the CB2 receptor with
effectively no affinity for the CB1 receptor.
The 3-(4-ethoxy-1-naphthoyl)indoles have from some-
what to considerably lower affinity for both receptors
than the 4-methoxy analogs (Table 2). At the CB1 recep-
tor the 1-propyl compounds have Ki = 220 29nM and
Ki = 767 105nM, respectively, for 1-propyl-3-(4-eth-
oxy-1-naphthoyl)indole (JWH-259) and 2-methyl-1-pro-
pyl-3-(4-ethoxy-1-naphthoyl)indole (JWH-261). JWH-259
has modest affinity (Ki = 74 7nM), while the 2-
methyl analog (JWH-261) has even less affinity
(Ki = 221 14nM) at the CB2 receptor. The 1-pentyl
compounds have considerably greater affinity for both
receptors than the corresponding 1-propylindoles. 1-
Pentyl-3-(4-ethoxy-1-naphthoyl)indole (JWH-258) has
Ki = 4.6 0.6nM at CB1 and Ki = 10.5 1.3nM at the
CB2 receptor. The 2-methyl compound, 2-methyl-1-
pentyl-3-(4-ethoxy-1-naphthoyl)indole (JWH-260) has
Ki = 29 0.4nM at CB1 and Ki = 25 1.9nM at the
CB2 receptor.
In the 7-methoxy-1-naphthoyl series (Table 2), neither
of the 1-propyl compounds has high affinity for either
the CB1 or CB2 receptor. 1-Propyl-3-(7-methoxy-1-
naphthoyl)indole (JWH-165) has Ki = 204 26nM
at the CB1 receptor and Ki = 71 8nM at the CB2
receptor. The 2-methyl analog (JWH-160) has
Ki = 1568 201nM at CB1 and Ki = 441 110nM at
CB2. In contrast, 1-pentyl-3-(7-methoxy-1-naph-
thoyl)indole (JWH-164) has Ki = 6.6 0.7nM at the
CB1 receptor and Ki = 6.9 0.2nM at the CB2 receptor.
The compound with the 2-methyl group, 2-methyl-1-
pentyl-3-(7-methoxy-1-naphthoyl)indole
(JWH-159),
has somewhat less affinity for the CB1 receptor than
JWH-164 with Ki = 45 1nM and similar affinity for
the CB2 receptor, Ki = 10.4 1.4nM.
None of the 1-alkyl-3-(2-methoxy-1-naphthoyl)indoles
(JWH-265–JWH-268, Table 2) have significant affinity
for the CB1 receptor, with Ki = 381 16nM for 1-
pentyl-3-(2-methoxy-1-naphthoyl)indole (JWH-267) to
Ki = >10,000nM for the 1-propyl-2-methyl analog
(JWH-266). The CB2 receptor affinities of this series of
compounds are considerably greater than for the CB1
Three of the indole derivatives synthesized in the course
of this SAR study are highly selective for the CB2 recep-
tor. These are 1-propyl-3-(4-methyl-1-naphthoyl)indole,
JWH-120 (41) which is 173-fold selective, 1-pentyl-3-(2-
methoxy-1-naphthoyl)indole, JWH-267 (32), 53-fold
selective and 1-propyl-2-methyl-3-(6-methoxy-1-naph-
thoyl)indole, JWH-151 (42) which is >333-fold selective.
In order to evaluate the efficacy of these compounds,
their ability to stimulate GTPcS binding was deter-
mined. This is a functional assay, which measures G-
protein coupled receptor activation using [35S]GTPcS
binding.43 Chinese Hamster Ovary (CHO) cells stably
expressing the human CB2 receptor were employed in
this determination (see Experimental). The results of
these determinations are summarized in Table 3. The
stimulation is normalized to that produced by a maxi-
mally effective concentration (3lM) of the standard
cannabinoid agonist CP-55,940 (2). CP-55,940 stimu-
lated [35S]GTPcS binding with an Emax value of
85 6.3% above basal (normalized to 100%) and an
EC50 value of 0.69 0.23nM. In addition to indoles
32, 41 and 42 the [35S]GTPcS binding for JWH-015,
1-propyl-2-methyl-3-(1-naphthoyl)indole (6), the lead
compound for the search for CB2 selective cannabimi-
metic indoles, was determined, and the data are included
in Table 3. Also included in Table 3 are data for two
receptor.
1-Propyl-3-(2-methoxy-1-naphthoyl)indole
(JWH-265) has moderate affinity, Ki = 80 13nM, for
the CB2 receptor while the 2-methyl analog (JWH-266)
has little affinity for the receptor, Ki = 455 55nM.
1-Pentyl-3-(2-methoxy-1-naphthoyl)indole (JWH-267)
has very high affinity, Ki = 7.2 0.14nM, for the CB2
receptor and the 2-methyl compound (JWH-268) has
somewhat less affinity with Ki = 40 1nM.
The only 6-methoxy-1-naphthoylindole with significant
affinity for the CB1 receptor is 1-pentyl-3-(6-methoxy-
1-naphthoyl)indole (JWH-166, Table 2) which has good
affinity with Ki = 44 10nM. The affinities of the other
three members of this series for the CB1 receptor range
from Ki = 240 24nM for 2-methyl-1-pentyl-3-(6-meth-
oxy-1-naphthoyl)indole (JWH-153) to Ki = >10,000 for
the 1-propyl-2-methyl analog (JWH-151, 42). The
1-pentyl-3-(6-methoxy-1-naphthoyl)indoles (JWH-153,
JWH-166) have similar and high CB2 affinities with
Table 3. EC50 and Emax values (mean SEM) for GTPcS binding for CB2 selective ligands
Compound
EC50 (nM)
Emax (% CP-55940)
CP55,940 (2)
0.69 0.23
17.7 1.0
4.0 1.0
4.6 2.0
5.1 1.6
4.9 0.8
12.0 2.9
100 7.4abc
65.7 6.4d
2-Methyl-1-propyl-3-(1-naphthoyl)indole (JWH-015, 6)
1-Deoxy-3-(10,10-dimethylbutyl)-D8-THC (JWH-133, 43)
1-Methoxy-3-(10,10-dimethylhexyl)-D8-THC (JWH-229, 44)
1-Propyl-3-(4-methyl-1-naphthoyl)indole (JWH-120, 41)
1-Pentyl-3-(2-methoxy-1-naphthoyl)indole (JWH-267, 32)
1-Propyl-2-methyl-3-(6-methoxy-1-naphthoyl)indole (JWH-151, 42)
111.5 13.6a
75.7 8.3cd
78.1 10.7bcd
67.3 2.9d
108.5 13.0ab
Assays were carried out in human CB2 receptor-expressing CHO cells. Emax values are reported as percent maximal stimulation by CP-55,940 (2).
Emax values not connected by the same letter designation are significantly different (p < 0.05).

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
97
dibenzopyran-based cannabinoids, which are highly
selective for the CB2 receptor, 1-deoxy-3-(10,10-dimeth-
ylbutyl)-D8-THC (JWH-133, 43), which has excellent
affinity for the CB2 receptor (Ki = 3.4 1.0nM) and lit-
tle affinity for the CB1 receptor (Ki = 677 132nM)44
and 1-methoxy-3-(10,10-dimethylhexyl)-D8-THC (JWH-
229, 44) with Ki = 18 2nM at CB2 and
Ki = 3134 110nM at CB1.45 The results showed that
Emax values of most of these compounds were not signif-
icantly different from CP-55,940, although two of the in-
doles (6 and 32) were less efficacious than CP-55,940.
Moreover, although 42 and 43 were not significantly dif-
ferent from CP-55,940, these compounds were more effi-
cacious than 6, 32, and 44(and 43 was more efficacious
than 41).
have Ki<45nM, indicative of high affinity for the recep-
tor. Replacing the hydrogen at C-4 of the naphthalene in
JWH-018 and JWH-007 (5) with a methyl (JWH-122,
JWH-149), ethyl (JWH-210, JWH-213) or propyl
(JWH-182, JWH-181) group leads to a considerable in-
crease in CB1 receptor affinity, however a butyl group at
C-4 (JWH-240, JWH-242) results in a decrease in affin-
ity (Table 1). Neither a 7-methyl-1-napthoyl (JWH-048,
9) nor a 7-ethyl-1-naphthoyl (JWH-234, JWH-262) sub-
stituent has a significant effect on affinity for the CB1
receptor.
With methoxynaphthoyl substituents along with reten-
tion of the N-pentyl group, a 2-methoxy-1-naphthoyl
(JWH-267, JWH-268) substituent effectively destroys
affinity for the CB1 receptor while a 4-methoxy group
(JWH-081, JWH-098) slightly increases affinity relative
to the unsubstituted analogs (JWH-018 and JWH-007,
5). Replacing the 4-methoxy group with a 4-ethoxy
(JWH-258, JWH-260) diminishes CB1 affinity some-
what. A 6-methoxy-1-naphthoyl substituent decreases
affinity for the CB1 receptor in the compound unsubsti-
tuted at C-2 of the indole nucleus (JWH-166,
Ki = 44 10nM); while the 2-methyl analog (JWH-
153) has little affinity. In contrast, the 7-methoxy ana-
logs (JWH-164 and JWH-159) have receptor affinities
comparable to those of the 4-ethoxy compounds.
H3CO
O
O
H3C
CH3
N
C3H7
H3C
N
C3H7
42
41
CH3
OCH3
H3C
H3C
CH3
CH3
H3C
H3C
CH3
CH3
CH3
CH3
The N-propyl indoles have significantly less affinity for
the CB1 receptor than the corresponding N-pentyl com-
pounds. Although an indole 2-methyl group usually
attenuates CB1 receptor affinity somewhat, in the case
of the compounds with an unsubstituted naphthoyl
group (JWH-015, 6, JWH-072) and the 4-methyl-1-
naphthoyl analogs (JWH-120, 41, JWH-148) the 2-
methyl compounds have CB1 receptor affinities an order
of magnitude greater than the unsubstituted compounds
(Table 1). A similar situation exists with the 1-propyl-3-
(4-butyl-1-naphthoyl)indoles (JWH-239, JWH-241);
however the 2-methyl analog (JWH-241) with
Ki = 147 20nM has only slightly more than two-fold
greater affinity for the CB1 receptor than JWH-239 with
Ki = 342 20nM. With the exception of the 4-ethyl-
(JWH-211, JWH-212), and 4-propyl-1-naphthoylindoles
(JWH-180, JWH-189) none of the N-propyl-alkyl-1-
naphthoyl compounds has a CB1 receptor affinity less
than 100nM. In the N-pentyl series the 4-propyl-1-naph-
thoylindoles (JWH-182, JWH-181) have exceptionally
high affinity for the CB1 receptor, with Ki = 0.65
0.03nM and 1.3 0.1nM, respectively (Table 1). These
high affinities are reflected in the N-propyl compounds
with Ki = 26 2nM for the 2H indole (JWH-180)
and Ki = 70 0.8nM for the 2-methyl analog (JWH-
189).
O
O
43
44
As indicated in Table 3 all six of these compounds are
potent in the [35S]GTPcS assay with EC50 values from
4.0 1.0nM for JWH-133 (43) to 17.7 1.0nM for
JWH-015 (6). Two of these CB2 receptor ligands,
JWH-133 (43) and 1-propyl-2-methyl-3-(6-methoxy-1-
naphthoyl)indole, JWH-151 (42) are highly efficacious
with Emax values of 111.5 13.6% and 108.5 13.0%,
respectively, relative to CP-55,940. The other three
cannabimimetic indoles, 1-propyl-2-methyl-3-(1-naph-
thoyl)indole, JWH-015 (6), 1-propyl-3-(4-methyl-1-
naphthoyl)indole, JWH-120 (41) and 1-pentyl-3-(2-
methoxy-1-naphthoyl)indole, JWH-267 (32), plus 1-
methoxy-3-(10,10-dimethylhexyl)-D8-THC,
(44) are all partial agonists relative to JWH-133 with
Emax values from 65.7 6.4% (JWH-015) to
78.1 10.7% (JWH-120).
JWH-229
3. Discussion
The 1-pentyl series of cannabimimetic indoles provided
several important structural criteria for recognition of
the CB1 receptor. As noted previously, affinity for the
CB1 receptor is attenuated slightly by the presence of a
methyl group at the 2-position of the indole. With the
In the methoxynaphthoyl series (Table 2) the relative
magnitudes of the CB1 receptor affinities for the N-pro-
pyl indoles parallel those of the N-pentyl analogues.
However, the compounds in this series have little
affinity for the CB1 receptor with affinities from
204nM to >10,000nM with the exception of 1-propyl-
3-(4-methoxy-1-naphthoyl)indole, JWH-079, which has
Ki = 63 3nM.
exception
of
the
1-pentyl-3-(2-methoxy-1-naph-
thoyl)indoles (JWH-267, 32, Ki = 381 16nM and
JWH-268, 33, Ki = 1379 193nM) and 1-pentyl-2-
methyl-3-(6-methoxy-1-naphthoyl)indole (JWH-153,
Ki = 250 24nM) all of the compounds in this series

98
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
To gain insight into the receptor interactions responsible
for the SAR of these cannabimimetic indoles at the CB1
receptor, molecular modeling and receptor docking
studies were carried out. NMR solution and X-ray crys-
tallography studies showed that 3-aroylindoles can exist
in two distinct conformations, which differ primarily in
the orientation of the C-3 aroyl system.14 In the s-trans
conformation, which predominates when the indole C-2
substituent is a hydrogen, the aryl system is near C-2,
while the carbonyl oxygen is located near C-4. In the
s-cis conformation, which predominates in 2-methylin-
doles, the aryl ring is located near C-4, and the carbonyl
oxygen is located near C-2. Recent AM1 conformational
analysis of a series of naphthyoylindoles identified both
s-cis and s-trans conformations for these compounds
with these same trends in preferred conformation
dependent on C-2 substitution.24 A study of rigid C-
2H and C-2-methyl naphthylidene-substituted amino-
alkylindene analogs of the cannabimimetic indoles that
mimic the s-cis (Z-indene) or the s-trans (E-indene) in-
dole conformation indicated that the E-isomer has the
higher CB1 and CB2 affinities and the higher pharmaco-
logical potency for both the C-2H and C-2-methyl
analogs.46 These results suggest that the s-trans confor-
mation is the preferred conformation for the interaction
of cannabimimetic indoles with both the CB1 and CB2
receptors.
2H analogs, the s-trans conformation is more stable
than the s-cis conformation, while for the C-2 methyl
analogs, the situation is reversed and the s-cis conforma-
tion is more stable. Figure 1 illustrates the conforma-
tional differences between the global minimum energy
conformer of a C-2H indole, 1-pentyl-3-(4-propyl-1-
naphthoyl)indole (JWH-182, Table 1, s-trans in yellow)
and the 2-methylindole analog, (JWH-181, s-cis in
green).
For 1-propyl-3-(4-propyl-1-naphthoyl)indole (JWH-
180, Table 1) and 1-propyl-3-(6-methoxy-1-naph-
thoyl)indole (JWH-163, Table 2), the C-2H analogs with
N-propyl side chains, the global minimum energy s-trans
conformers were found to be more stable than the low-
est energy s-cis conformers by 0.55 and 0.56kcal/mol,
respectively. For the C-2H analogs with N-pentyl side
chains, 1-pentyl-3-(4-propyl-1-naphthoyl)indole (JWH-
182), 1-pentyl-3-(2-methoxy-1-naphthoyl)indole (JWH-
267, 32), and 1-pentyl-3-(6-methoxy-1-naphthoyl)indole
(JWH-166), the global minimum energy s-trans con-
former was found to be more stable than the lowest en-
ergy s-cis conformer by 0.55, 0.64, and 0.54kcal/mol,
respectively.
For 2-methyl-1-propyl-3-(4-propyl-1-naphthoyl)indole
(JWH-189, Table 1) and 2-methyl-1-propyl-3-(6-meth-
oxy-1-naphthoyl)indole (JWH-151, 42, Table 2) the C-
2 methyl analogs, with N-propyl side chains, the global
minimum energy s-cis conformers were found to be
more stable than the lowest energy s-trans conformers
by 1.28 and 1.33kcal/mol, respectively. For the C-2-
methyl analogs with N-pentyl side chains, 2-methyl-1-
pentyl-3-(4-propyl-1-naphthoyl)indole (JWH-181, Table
1), 2-methyl-1-pentyl-3-(2-methoxy-1-naphthoyl)indole
(JWH-268, 33, Table 2), and 2-methyl-1-pentyl-3-(6-
methoxy-1-naphthoyl)indole (JWH-153), the global
minimum energy s-cis conformers were found to be
For the current modeling studies, a set of 3-(4-propyl-1-
naphthoyl)indoles (JWH-180, JWH-189, JWH-182,
JWH-181, Table 1) and a set of 3-(6-methoxy-1-naph-
thoyl)indoles (JWH-163, JWH-151, 42 JWH-166,
JWH-153, Table 2) were chosen. In addition, the
N-pentyl-3-(2-methoxy-1-naphthoyl)indoles (JWH-267,
32 and JWH-268, 33, Table 2) were examined.
AM1 conformational search results were consistent with
the data discussed above which have shown that for C-
Figure 1. (a) The global minimum energy conformers of JWH-182 (s-trans; in yellow) and JWH-181 (s-cis; in green) are superimposed at their indole
rings. (b) A top view of the global minimum energy conformers of JWH-182 (s-trans; in green) and JWH-181 (s-cis; in yellow) superimposed at their
indole rings is presented here. The molecules are oriented so that the indole ring is perpendicular to the page with C-4 pointing towards the viewer
and the C-2 methyl of JWH-181 pointing to the left.

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
99
more stable than the lowest energy s-trans conformers
by 1.27, 0.59, and 1.30kcal/mol, respectively.
Substitution at C-6 of the naphthyl ring results in dimin-
ished affinity for 1-pentyl-3-(6-methoxy-1-napht-
hoyl)indole (JWH-166, Ki = 44 10nM, Table 2)
relative to the 4-propyl-1-naphthoyl analog (JWH-182,
Ki = 0.65 0.03nM, Table 1). A methoxy substituent
at C-6 in its lowest energy conformation (in the naphthyl
ring plane) has some steric conflicts with L5.50 and
V3.40, which can be alleviated by rotation of the 6-
methoxy group ꢀ96ꢁ out of the plane of the naphthyl
ring into a higher energy rotameric state. The necessity
for the methoxy group to assume a higher energy con-
formation in order to be accommodated at the binding
site, likely contributes to the reduced CB1 affinity of
JWH-166 relative to JWH-182.
Based upon recent CB1 mutation studies of the aro-
matic microdomain formed by transmembrane helices
(TMHs) 3-4-5-6 of CB1 McAllister et al. suggested
that the TMH 3-4-5-6 region is the binding site region
for WIN-55,212-2 (4).47 This result is consistent with
CB1/CB2 chimera studies, which suggested that the
TMH 4-E2-TMH 5 region of CB1 was important for
WIN-55,212-2 binding.48 1-Pentyl-3-(4-propyl-1-naph-
thoyl)indole (JWH-182) is the highest affinity analog
in the series of compounds reported here (Ki =
0.65 0.03nM, Table 1). Because JWH-182 is also a
highly aromatic compound structurally related to
WIN-55212-2, JWH-182 was docked in the aromatic
microdomain region (TMH 3-4-5-6 region) of CB1.
The binding site for JWH-182 identified in these docking
studies was also in the same region as that identified pre-
viously for 1-pentyl-3-(4-methoxy-1-naphthoyl)indole
(JWH-081) and 2-methyl-1-pentyl-3-(4-methoxy-1-
naphthoyl)indole (JWH-098).24 Docking studies re-
vealed that at the binding site, the N-pentyl tail of
JWH-182 extends over F3.36 and the indole moiety is
parallel and between TMH 5 and TMH 6. The naphthyl
ring is below (intracellular to) both W5.43 and W6.48,
with the 4-propyl substituent on the naphthyl ring lo-
cated in an open area within the binding pocket. In this
position, the indole ring has aromatic stacking interac-
Substitution at C-7 of the naphthyl ring results in a
slight reduction in affinity for 1-pentyl-3-(7-methoxy-1-
naphthoyl)indole (JWH-164, Ki = 6.6 0.7nM, Table
2). Docking studies show that a methoxy substituent
at C-7 encounters no steric problems when it is in its
minimum energy conformation (in the plane of the
naphthyl ring). However, the 7-methoxy group blocks
the aromatic stacking interaction between the naphthyl
ring and W5.43, which is present in the 4-propyl analog
(JWH-182). This loss of an aromatic stacking interac-
tion may account for the 10-fold reduction in affinity
of JWH-164 relative to JWH-182.
A study of rigid naphthylidene-substituted aminoalkyl-
indene analogs of cannabimimetic indoles that mimic
the s-cis (Z-indene) or s-trans (E-indene) conformation
of the indoles indicated that the E-isomers (which mimic
the s-trans conformation of the indole) have the higher
CB1 and CB2 receptor affinities and the higher pharma-
cological potencies.46 These results suggest that the
s-trans conformation is the preferred conformation for
the interaction of cannabimimetic indoles at both the
CB1 and CB2 receptors. For this reason, the lowest
energy s-trans conformer of 2-methyl-1-pentyl-3-(4-
˚
tions with W5.43 (d = 4.6A, a = 80ꢁ) and W6.48
˚
(d = 6.1A, a = 60ꢁ). The naphthyl ring also has stacking
interactions with both residues: W5.43 (d = 5.1A,
˚
˚
a = 30ꢁ) and W6.48 (d = 5.7A, a = 70ꢁ). In this dock-
ing position, the carbonyl oxygen forms a weak
˚
hydrogen-bond with W6.48 (O–Ndbond2.7A, O–H–
N = 156ꢁ).
Using the docking position employed for JWH-182, the
consequences of substitution at other positions on the
naphthyl ring were explored. Substitution at the 2-
naphthoyl position as in 1-pentyl-3-(2-methoxy-1-
naphthoyl)indole (JWH-267, Ki = 381 16nM, Table
2) causes a great diminishment in affinity relative to
the 4-methoxy-1-naphthoyl analog (JWH-182). Docking
studies showed that the 2-methoxy group in JWH-267
has severe steric conflicts with W6.48 that can be re-
lieved only by backing the ligand away from W6.48,
causing the ligand to lose most of its aromatic stacking
interactions.
propyl-1-naphthoyl)indole
(JWH-181,
Ki = 1.30
0.1nM, Table 1), rather than its global minimum energy
s-cis conformer was used in the docking studies. Because
of the use of the s-trans conformer as the bioactive con-
formation for the N-pentyl C-2 methyl indoles, the affin-
ities of ligands in this series can, in general, be expected
to be reduced relative to those of the corresponding
C-2H indoles for which the global minimum energy con-
formers are s-trans conformers. Such a general reduction
is, in fact, seen in this series (Tables 1 and 2).
Docking studies revealed that various substituents can
be placed at C-4 of the naphthoyl moiety without any
significant decrease in affinity because there is a fairly
wide and deep lipophilic binding pocket in this region
formed by L3.43, V3.40, L6.44, and I5.54. 1-Pentyl-3-
(4-butyl-1-naphthoyl)indole (JWH-240, Ki = 14.1
1.3nM), for example, places greater bulk at C-4 of the
naphthyl ring than is present in JWH-182 (4-propyl-1-
naphthoyl). Docking studies indicated that the C-4 of
the naphthoyl substituent can accommodate the bulkier
4-butyl substituent by a slight adjustment in the place-
ment of the butyl substituent in order to eliminate con-
flict with I5.54 and L6.44.
Docking studies of the lowest energy s-trans conformer
of
2-methyl-1-pentyl-3-(4-propyl-1-naphthoyl)indole
(JWH-181, Ki = 1.30 0.1nM, Table 1) in the TMH
3-4-5-6 region of the CB1 receptor revealed that JWH-
181 sits higher (i.e., closer to extracellular) in the binding
site region than does the C-2H analog (JWH-182). At
this docking site, the indole ring of JWH-181 has aro-
˚
matic stacking interactions with W5.43 (d = 4.6A,
˚
a = 90ꢁ) and W6.48 (d = 6.3A, a = 70ꢁ). The naphthyl
moiety also has a parallel stacking interaction with
˚
W5.43 (d = 4.7A, a = 20ꢁ) and a T-stacking interaction
˚
with W6.48 (d = 6.1A, a = 70ꢁ). The carbonyl oxygen
forms a hydrogen bond with W6.48 (O–N = 2.7A
˚

100
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
O–H–N = 162ꢁ). The N-1 pentyl alkyl chain of JWH 181
can still interact with the hydrophobic binding pocket
formed by L3.29, V3.32, and I6.54. The 4-position of
the naphthoyl group is oriented such that substituents
can reach a hydrophobic pocket formed by L3.43,
V3.40, L6.44, and I5.54. This pocket can accommodate
the bulkier 4-butyl substituent by a slight adjustment in
the placement of the butyl substituent in order to elimi-
nate conflict with I5.54 and L6.44.
stacking interactions. As a result, ligands with the pro-
pyl substituent may have more difficulty in assuming
the correct aromatic region orientation necessary for
productive binding at the CB1 receptor.
The importance of an alkyl chain of certain length (in the
present case, pentyl) is very reminiscent of the classical
cannabinoids for which it has been shown that C-3 alkyl
chains shorter than pentyl have severely reduced CB1
affinities, while those with a 1,1-dimethylheptyl side
chain have optimal affinity.2–6 The N-propyl analogs
with a 4-alkyl naphthyl substituent have the highest affin-
ities in the series. This is probably because the 4-alkyl
substituent can access the other hydrophobic pocket
comprised of L3.43, V3.40, L6.44, and I5.54 mentioned
above for the 1-pentyl-3-(4-alkyl-1-naphthoyl)indoles.
The ability of these analogs to interact with and be ori-
ented by this pocket appears to compensate for the lack
of an N-alkyl chain of appropriate length, and permits
the proper orientation of the aromatic rings of the ligand
for aromatic stacking interactions in the CB1 receptor.
In 2-methyl-1-pentyl-3-(2-methoxy-1-naphthoyl)indole
(JWH-268, 33, Ki = 1379 193nM, Table 2) substitu-
tion at C-2 of the naphthalene ring causes a great loss
of affinity relative to JWH-181. Docking studies show
that the 2-methoxy group in JWH-268 has severe steric
conflicts with W6.48 that can be relieved only by back-
ing the ligand away from W6.48, causing the ligand to
lose its aromatic stacking interactions.
In the N-pentyl, C-2H series substitution of a methoxy
group at C-6 of the naphthoyl group causes a reduction
in affinity, while substitution at C-7 does not cause as ex-
treme a reduction in CB1 receptor affinity. For 1-pentyl-
3-(6-methoxy-1-naphthoyl)indole (JWH-166, Table 2),
Ki = 44 10nM; while for 1-pentyl-3-(7-methoxy-1-
naphthoyl)indole (JWH 164) Ki = 6.6 0.7nM. In the
N-pentyl, C-2 methyl series, substitution at the 6- or
7-position has a more profound effect on affinity.
For 2-methyl-1-pentyl-3-(6-methoxy-1-naphthoyl)indole
(JWH-153) Ki = 250 24nM; and for the 7-methoxy
analog (JWH-159) Ki = 45 1nM). Some of this de-
crease in affinity is possibly caused by the assumption
of an s-trans conformation (see above), however, addi-
tional changes were found in the binding sites for these
two analogs. Both the 6- and 7-methoxy analogs can be
positioned in the same binding pocket as the C-2H in-
doles, however, because the molecule is higher in the
binding pocket, the 6-methoxy group in JWH-153 has
steric interactions with L5.50, V3.40, and W5.43 that
would cause it to have reduced affinity for the CB1
receptor.
In contrast to the SAR at the CB1 receptor, the presence
of an indole 2-methyl group in most of the compounds
with an unsubstituted or alkyl naphthoyl substituent
has minimal effect upon CB2 affinity relative to the corre-
sponding 2H-indole, and in several cases CB2 receptor
affinity is increased (Table 1). In two cases the CB2 recep-
tor affinity of the 2-methyl compound is greater than six-
fold that of the unsubstituted analog. For the parent
compound,
2-methyl-1-propyl-3-(1-naphthoyl)indole
(JWH-015, 6), Ki = 13.8 4.6nM, while the 2H analog
(JWH-072) has Ki = 170 54nM. A similar situation
prevails with 2-methyl-1-propyl-3-(7-methyl-1-napht-
hoyl)indole (JWH-046, 8), Ki = 16 5nM and
1-propyl-3-(7-methyl-1-naphthoyl)indole
(JWH-076)
with almost sevenfold less CB2 receptor affinity
(Ki = 106 46nM). The situation is reversed, however,
for most of the methoxynaphthoyl indoles. With the
exception of 1-pentyl-3-(4-methoxy-1-naphthoyl)indole
(JWH-081, Ki = 12.4 2.2nM), and its 2-methyl analog
(JWH-098, Ki = 1.9 0.3nM); 1-propyl-3-(6-methoxy-
1-naphthoyl)indole (JWH-163, Ki = 138 12nM), and
its 2-methyl analog (JWH-151, Ki = 30 1.1nM), the
2H-indoles in this series have higher affinity for the
CB2 receptor than the 2-methylindoles (Table 2).
Substitution at the C-7 of the naphthoyl ring system re-
sults in another lower affinity analog. 2-Methyl-1-pent-
yl-3-(7-methoxy-1-naphthoyl)indole (JWH-159, Ki =
45 1nM, Table 2) has considerably less affinity for
the CB1 receptor than 1-pentyl-3-(7-methoxy-1-napht-
hoyl)indole (JWH-164, Ki = 6.6 0.7nM). Docking
studies showed that a methoxy group at C-7 must rotate
out of plane by 16ꢁ in order to avoid a steric clash with
V5.46. This change from a minimum energy rotameric
state for the methoxy group may contribute to the de-
crease in CB1 affinity seen for this analog.
Although, with few exceptions, the N-propyl indoles
have little affinity for the CB1 receptor, and all have less
affinity than the corresponding N-pentyl compound, in
general, in the alkylnaphthoyl series the N-propyl in-
doles have only slightly less affinity for the CB2 receptor
than their N-pentyl congeners (Table 1). An exception to
this generalization is 1-propyl-3-(1-naphthoyl)indole
(JWH-072, Ki = 170 54nM) and 1-pentyl-3-(1-naph-
thoyl)indole (JWH-018, Ki = 2.9 2.6nM). Also, for
all the 7-substituted compounds the N-pentyl indoles
(JWH-048, JWH-234, JWH-262) have from 32 to over
300-fold greater affinity for the CB2 receptor than the
N-propyl compounds (JWH-076, JWH-235, JWH-236).
Compared to their N-pentyl congeners, each analog in
the N-propyl series shows reduced CB1 receptor affinity.
In the N-pentyl series, the pentyl tail resides in a hydro-
phobic binding pocket formed by L3.29, V3.32, and
I6.54. The utility of this pocket appears to lie in its abil-
ity to orient aromatic rings of the ligand for aromatic
stacking interactions with the receptor. The N-propyl
tail is too short to access this hydrophobic pocket and
simultaneously allow the ligand to engage in aromatic
In the methoxynaphthoyl series the effects of substitu-
tion at the 2-position of the indole upon CB2 receptor

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
101
affinity are similar to those at the CB1 receptor, and
the 2-methyl indoles have less receptor affinity than
the unsubstituted compounds (Table 2). There are,
however, several exceptions. 1-Pentyl-3-(4-methoxy-1-
naphthoyl)indole (JWH-081, Ki = 12.4 2.2nM) has
somewhat less affinity for the CB2 receptor than the
corresponding 2-methyl compound (JWH-098, Ki =
1.9 0.3nM). Also, 1-propyl-3-(6-methoxy-1-napht-
hoyl)indole (JWH-163, Ki = 138 12nM) has signifi-
cantly less affinity for the CB2 receptor than the
2-methyl analog (JWH-151, 42, Ki = 30 1.1nM). In
the methoxy series, as in the case of the CB1 affinities,
the N-propyl indoles all have less affinity for the CB2
receptor than the N-pentyl compounds.
alkoxynaphthoyl series there is no clear pattern. Most
of the alkoxynaphthoyl cannabimimetic indoles have
good to moderate affinity for the CB2 receptor, however
a 1-propyl-2-methylindole substitution pattern leads to
attenuated affinity in several cases.
A 2-methyl substituent on the indole nucleus results in a
decrease in affinity for either receptor relative to the
unsubstituted analog. Similarly, the 1-propylindoles in
general have lower affinities at both receptors than the
1-pentyl compounds. However, the differences in CB2
receptor affinities as a function of N-substitution are less
pronounced than is the case with CB1 affinities.
Although three new cannabimimetic indoles with poten-
tially useful CB2 selectivity have been identified, there do
not appear to be sufficient data to permit the rational de-
sign of additional indole-based CB2 selective ligands.
Although the CB1 receptor affinities of the methoxy
naphthoyl indoles range from 1.2nM to >10,000nM,
the range for the CB2 affinities is not nearly as large
(Table 2). Only four of this series of analogs have
Ki = >100nM. All of these compounds, 2-methyl-1-pro-
pyl-3-(2-methoxy-1-naphthoyl)indole (JWH-266, Ki =
455 55nM), 2-methyl-1-propyl-3-(7-methoxy-1-napht-
hoyl)indole (JWH-160, Ki = 441 110nM), 2-methyl-1-
5. Experimental
5.1. General
propyl-3-(4-ethoxy-1-naphthoyl)indole
(JWH-261,
IR spectra were obtained using Nicolet 5DX or Magna
1
Ki = 221 14nM) and 1-propyl-3-(6-methoxy-1-napht-
hoyl)indole (JWH-163, Ki = 138 12nM) are N-propyl
indoles, which also have very weak CB1 receptor affini-
ties. However, only two N-propyl compounds,
1-propyl-3-(4-methoxy-1-naphthoyl)indole (JWH-079,
Ki = 32 6nM) and 2-methyl-1-propyl-3-(6-methoxy-1-
naphthoyl)indole (JWH-151, 42, Ki = 30 1.1nM)
have CB2 receptor affinities of less than 70nM.
All of the N-pentyl analogs have from good to
excellent affinity for the CB2 receptor with Ki < 41nM
(Table 2).
spectrometers; H and 13C NMR spectra were recorded
on a Bruker 300AC spectrometer. Mass spectral analy-
ses were performed on a Hewlett–Packard 5890A capil-
lary gas chromatograph equipped with a mass sensitive
detector. HRMS data were obtained in the Mass Spectro-
metry Laboratory, School of Chemical Sciences, Uni-
versity of Illinois. Ether and THF were distilled from
Na-benzophenone ketyl immediately before use, and
other solvents were purified using standard procedures.
Column chromatography was carried out on Sorbent
Technologies silica gel (32–63l) using the indicated sol-
vents as eluents. All new compounds were homogeneous
to TLC and 13C NMR. All target compounds were
homogeneous to GLC or TLC in two different solvent
systems. TLC was carried out using 200lm silica gel
plates using the indicated solvents. GLC analyses were
performed on the Hewlett–Packard 5890A GC/MS
using a 60m carbowax column and helium gas as a car-
rier. An initial column temperature of 60ꢁC was em-
ployed and the temperature was increased at a rate of
15ꢁC/min to a maximum temperature of 300ꢁC with a
total run time of 20min. Elemental analyses were per-
formed by Atlantic Microlab, Norcross, GA.
4. Conclusions
The CB1 receptor affinities for 1-pentyl- and 1-propyl-3-
(1-naphthoyl)indoles with 4- and 7-alkylnaphthoyl and
2-, 4-, 6-, 7-methoxy and 4-ethoxynaphthoyl substitu-
ents indicate that receptor affinity is enhanced consider-
ably by the presence of small alkyl groups (methyl,
ethyl, propyl) at C-4. Methyl or ethyl substituents at
C-7 of the naphthoyl group have little effect on affinity
relative to the unsubstituted compounds. A methoxy
substituent at C-4 enhances CB1 receptor affinity, while
a 4-ethoxy substituent has relatively little effect on affin-
ity. 6-Methoxy-1-naphthoylindoles have attenuated CB1
receptor affinities relative to the unsubstituted com-
pounds, while a 7-methoxy substituent has little effect
upon affinity. A 2-methoxy substituent effectively de-
stroys affinity for the CB1 receptor. These conclusions
have been rationalized in terms of molecular modeling
and receptor docking studies.
5.1.1. 1-Propyl-3-(4-methyl-1-naphthoyl)indole JWH-120
(41, method B). To a stirred solution of 0.080g
(0.50mmol) of 1-propylindole in 1.5mL of dry CH2Cl2
at 0ꢁC under N2 was added dropwise 0.75mL
(0.75mmol) of Me2AlCl (1M in hexanes). The solution
was stirred at 0ꢁC for 30min and a solution of 0.122g
(0.6mmol) of freshly prepared 4-methyl-1-naphthoyl
chloride in 1.5mL of CH2Cl2 was added. The acid chlo-
ride was prepared from 0.122g (0.60mmol) of 4-methyl-
1-naphthoic acid to which was added dropwise 1mL of
thionyl chloride at a rate sufficient to maintain a steady
evolution of gas. This solution was heated at reflux for
15min, cooled to ambient temperature and the excess
thionyl chloride was removed in vacuo to give the acid
chloride, which was used without further purification.
The CB2 receptor affinities of these naphthoylindoles
show considerably less variation than their CB1 affini-
ties. Only three compounds with alkylnaphthoyl substit-
uents have CB2 receptor affinities greater than 52nM;
the 1-propyl-3-(7-methyl or 7-ethyl-1-naphthoyl)indoles
and 1-propyl-3-(7-ethyl-1-naphthoyl)indole. In the

102
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
The deep red acylation reaction mixture was stirred at
0ꢁC until the reaction was complete as indicated by
TLC (approximately 1h). The reaction mixture was
poured carefully into iced 1M aqueous HCl and
extracted with three portions of CH2Cl2. The combined
extracts were washed with three portions of aqueous
NaHCO3, dried (MgSO4), and the solvent was removed
in vacuo to give the crude product. After chromatogra-
phy (petroleum ether/ethyl acetate, 9:1) there was ob-
tained 0.140g (86%) of indole 41 as a white solid.
Recrystallization from hexanes/ethyl acetate gave the
5.1.3. N,N-Diphenyl-4-ethyl-1-naphthalenecarboxamide
(19, R = C2H5). A mixture of 3.00g, (19.2mmol) of 1-
ethylnaphthalene, 4.45g (19.2mmol) of diphenylcarba-
myl chloride, and 2.82g (21.1mmol) of anhydrous AlCl3
in 38.4mL of 1,2-dichloroethane was heated at reflux for
6h. After cooling, the reaction mixture was poured onto
a mixture of ice and concentrated HCl and extracted
with ether. The extracts were dried (MgSO4) and the sol-
vent was removed in vacuo. The residue was chromato-
graphed (petroleum ether/ethyl acetate, 9:1) to give a
white solid. Recrystallization gave 1.72g (80%) of
amide, which was used in the next step without further
purification: mp 126–127ꢁC; 1H NMR (300MHz,
CDCl3) d 1.29 (t, J = 7.5Hz, 3H), 3.02 (q, J = 7.5Hz,
2H), 7.08–7.31 (m, 12H), 7.49–7.57 (m, 2H), 8.02
(d, J = 7.6Hz, 1H), 8.32 (d, J = 7.6Hz, 1H); 13C NMR
(75.5MHz, CDCl3) d 14.7, 26.0, 123.4, 124.0, 125.9,
126.1, 126.4, 127.2, 128.9, 131.0, 131.8, 132.6, 142.2,
143.2, 170.6; MS (EI) m/z 351 (12), 183 (100).
1
analytical sample: mp 207–208 ꢁC; H NMR (300MHz,
CDCl3) d 0.90 (t, J = 7.3Hz, 3H), 1.81–1.88 (m, 2H),
2.78 (s, 3H), 4.03 (t, J = 7.0Hz, 2H), 7.37–7.38 (m,
5H), 7.48–7.59 (m, 3H), 8.09 (d, J = 8.2Hz, 1H), 8.27
(d, J = 8.2Hz, 1H), 8.52–8.54 (m, 1H); 13C NMR
(75.5MHz, CDCl3) d 11.3, 19.7, 23.1, 48.7, 109.9,
117.6, 122.7, 122.9, 123.5, 124.2, 125.5, 125.8, 126.1,
126.3, 126.6, 127.0, 130.9, 132.8, 136.6, 137.0, 137.5,
137.9, 192.2; Anal. Calcd for C23H21NO: C, 84.37; H,
6.46; N, 4.28. Found: C, 84.25; H, 6.46; N, 4.30.
5.1.4. 4-Ethyl-1-naphthoic acid (15). A mixture of 3.70g
(10.5mmol) of the above diphenylamide, 23.2g of
KOH and 154mL of diethylene glycol was heated at re-
flux for 8h. The reaction mixture was cooled, diluted
with 1.13L of water, and the precipitated solids filtered
off. The filtrate was acidified with conc. HCL until pre-
cipitation was complete. The solid was collected and
dried to give 1.90g (90%) of acid 15: mp 125–127ꢁC
(lit. mp 129–130ꢁC, Ref. 26): 1H NMR (300MHz,
CDCl3) d 1.44 (t, J = 7.3Hz, 3H), 3.20 (q, J = 7.5Hz,
2H), 7.44 (d, J = 7.6Hz, 1H), 7.59–7.70 (m, 2H), 8.16
(d, J = 8.2Hz, 1H), 8.39 (d, J = 7.4Hz, 1H), 9.21 (d,
J = 8.6Hz, 1H); 13C NMR (75.5MHz, CDCl3) d 14.7,
26.5, 123.8, 124.1, 125.0, 126.1, 126.6, 127.5, 131.9,
132.1, 147.5, 173.7.
5.1.2. 2-Methyl-1-propyl-3-(4-methyl-1-naphthoyl)indole
JWH-148 (method A). To a stirred solution of 14.1mL
(42.3mmol) of 3.0M MeMgBr in ether, diluted with
20mL of THF, at 0ꢁC was added 4.62g (35.2mmol)
of 2-methylindole in 10mL of THF. The reaction mix-
ture was allowed to warm to ambient temperature and
a solution of 4-methyl-1-naphthoyl chloride (from
6.0g, 35mmol, of 4-methyl-1-naphthoic acid) in 5mL
of THF was added dropwise. The mixture was heated
at reflux for 1.5h and the reaction was quenched by
the cautious addition of saturated aqueous NH4Cl. Stir-
ring was continued until the solid precipitate was broken
up and the solid was collected, and suspended in 200mL
of methanol. A solution of 3g of KOH in 20mL of
water was added and the mixture was heated at reflux
for 4h. The precipitate was filtered off and dried to give
3.7g (35%) of 2-methyl-3-(4-methyl-1-naphthoyl)indole
as a pale brown solid, which was used in the subsequent
step without further purification. For N-alkylation,
1.75g (5.85mmol) of 2-methyl-3-(4-methyl-1-naph-
thoyl)indole was added to a stirred suspension of
1.48g of powdered KOH in 5mL of DMSO and 1.44g
(11.7mmol) of 1-bromopropane was added. The reac-
tion mixture was stirred at 80ꢁC for 18h, poured into
water, and extracted with three portions of ethyl acetate.
The combined extracts were washed with water, dried
(Na2SO4), and the solvent was removed to give the
crude product. Chromatography (petroleum ether/ethyl
acetate, 10:1) gave 1.62g (81%) of JWH-148 as a white
solid: mp 135–137ꢁC; 1H NMR (300MHz, CDCl3)
d 0.95 (t, J = 7.4Hz, 3H), 1.79 (sextet, J = 7.4Hz, 2H),
2.44 (s, 3H), 2.74 (s, 3H), 4.04 (t, J = 7.3Hz, 2H), 6.98
(t, J = 7.9Hz, 1H), 7.15 (t, J = 7.9Hz, 1H), 7.21–7.52
(m, 6H), 8.06 (d, J = 8.5Hz, 1H), 8.18 (d, J = 8.3Hz,
1H); 13C NMR (75.5MHz, CDCl3) d 11.6, 12.7, 20.0,
23.0, 44.9, 109.6, 115.2, 121.4, 121.9, 122.2, 124.4,
125.9, 126.2, 126.4, 126.6, 127.3, 130.6, 133.0, 136.2,
136.8, 139.0, 145.5, 193.7; MS (EI) m/z 341 (80), 326
(43), 324 (25), 141 (100); Anal. Calcd for C24H23NO:
C, 84.42; H, 6.79; N, 4.10. Found: C, 84.39; H, 6.83;
N, 4.08.
5.1.5. 1-Propyl-3-(4-ethyl-1-naphthoyl)indole, JWH-212
(method C). 4-Ethyl-1-naphthoic acid was converted to
the acid chloride by the procedure described above in
the preparation of 2-methyl-1-propyl-3-(4-methyl-1-
naphthoyl)indole (JWH-148). To a solution of 4-ethyl-
1-naphthoyl chloride, from 0.20g (1.00mmol) of 4-
ethyl-1-naphthoic acid in 4.0mL of toluene was added
a solution of 0.19g (1.20mmol) of 1-propylindole. The
solution was cooled to 0ꢁC and 0.26mL (1.5mmol) of
1.0M EtAlCl2 in hexanes was added dropwise with stir-
ring. The reaction mixture was warmed to ambient tem-
perature and stirred for 4days. After the addition of
2.0mL of water, the layers were separated and the aque-
ous layer was extracted with ethyl acetate. The
combined organic extracts were washed with water,
dried (MgSO4), and concentrated in vacuo. The residue
was chromatographed (petroleum ether/ether, 9:1) to
give 0.190g (56%) of JWH-212 as a yellow gum: 1H
NMR (300MHz, CDCl3) d 0.90 (t, J = 7.4Hz, 3H),
1.45 (t, J = 7.5Hz, 3H), 1.78–1.90 (m, 2H), 3.19 (q,
J = 7.4Hz, 2H), 4.04 (t, J = 7.1Hz, 2H), 7.35–7.40 (m,
5H), 7.44–7.53 (m, 2H), 7.55–7.61 (m, 2H), 8.14 (d,
J = 8.4Hz, 1H), 8.26 (d, J = 8.3Hz, 1H); 13C NMR
(75.5MHz, CDCl3) d 11.3, 14.9, 23.1, 26.1, 48.7, 109.9,
117.7, 122.7, 122.9, 123.5, 123.8, 124.6, 125.9, 126.0,
126.2, 126.8, 127.1, 131.1, 132.0, 137.0, 137.4, 137.9,

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
103
142.5, 192.6; MS (EI) m/z 341 (100), 324 (65), 312 (91);
HRMS Calcd for C24H23NO: 341.1780, Found
341.1779.
5.1.9. 4-Propyl-1-naphthoic acid (16). Acid 16 was pre-
pared in a manner analogous to that employed for 4-
ethyl-1-naphthoic acid: mp 134–135ꢁC (lit. mp 141–
1
142ꢁC, Ref. 26); H NMR (300MHz, CDCl3) d 1.06
(t, J = 7.3Hz, 3H), 1.78–1.86 (m, 2H), 3.13 (t,
J = 7.7Hz, 2H), 7.41 (d, J = 7.5Hz, 1H), 7.56–7.67 (m,
2H), 8.14 (d, J = 8.2Hz, 1H), 8.34 (d, J = 7.5Hz, 1H),
9.16 (d, J = 8.6Hz, 1H); 13C NMR (75.5MHz, CDCl3)
d 24.2, 23.8, 35.7, 123.9, 124.3, 124.9, 126.0, 126.6,
127.5, 131.6, 132.1, 132.3, 146.1, 172.9; MS (EI) m/z
214 (59), 185 (100), 157 (20).
5.1.6. 1-Pentyl-3-(4-ethyl-1-naphthoyl)indole, JWH-210.
JWH-210 was prepared from 4-ethyl-1-naphthoic acid
and 1-pentylindole by method C. From 0.20g
(1.00mmol) of 4-ethyl-1-naphthoic acid and 0.22g
(1.20mmol) of 1-pentylindole there was obtained after
chromatography (petroleum ether/ether, 9:1) 0.193g
(52%) of JWH-210 as a viscous oil: 1H NMR
(300MHz, CDCl3) d 0.88 (t, J = 6.9Hz, 3H), 1.24–1.35
(m, 3H), 1.40–1.49 (m, 4H), 1.76–1.85 (m, 2H), 3.21
(q, J = 7.5Hz, 2H), 4.05 (t, J = 7.2Hz, 2H), 7.35–7.42
(m, 5H), 7.49–7.52 (m 2), 7.55–7.64 (m, 2H), 8.16 (d,
J = 8.3Hz, 1H), 8.32 (d, J = 8.5Hz, 1H); 13C NMR
(75.5MHz, CDCl3) d 13.8, 14.8, 22.1, 26.1, 28.8, 29.4,
45.0, 109.9, 117.5, 122.6, 122.8, 123.4, 123.7, 124.0,
125.8, 126.0, 126.1, 126.7, 127.0, 131.1, 131.9, 136.9,
137.4, 137.8, 142.4, 192.2; MS (EI) m/z 369 (100), 352
(64), 312 (88); HRMS Calcd for C26H27NO: 369.2093,
Found 369.2090.
5.1.10. 1-Propyl-3-(4-propyl-1-naphthoyl)indole, JWH-
180. JWH-180 was prepared from 4-propyl-1-naphthoic
acid and 1-propylindole by method C. From 0.11g
(0.51mmol) of 4-propyl-1-naphthoic acid and 0.098g
(0.62mmol) of 1-propylindole there was obtained after
chromatography (petroleum ether/ether, 9:1) 0.098g
(54%) of JWH-180 as a gum: 1H NMR (300MHz,
CDCl3) d 0.90 (t, J = 7.4Hz, 3H), 1.08 (t, J = 7.3Hz,
3H), 1.80–1.88 (m, 4H), 3.12 (t, J = 7.7Hz, 2H), 4.05
(t, J = 7.1Hz, 2H), 7.34–7.43 (m, 5H), 7.46–7.50 (m,
2H), 7.52–7.60 (m, 2H), 8.12 (d, J = 8.1Hz, 1H), 8.24
(d, J = 8.1Hz, 1H); 13C NMR (75.5MHz, CDCl3) d
11.2, 14.3, 23.1, 23.8, 35.4, 48.7, 109.9, 117.6, 122.7,
122.9, 123.5, 124.0, 124.6, 125.7, 126.0, 126.1, 126.7,
127.0, 131.2, 132.2, 137.0, 137.5, 137.9, 141.0, 192.0;
MS (EI) m/z 355 (100), 338 (57), 326 (52); HRMS Calcd
for C25H25NO: 355.1936, Found 355.1924.
5.1.7. 2-Methyl-1-propyl-3-(4-ethyl-1-naphthoyl)indole,
JWH-211. JWH-211 was prepared from 4-ethyl-1-
naphthoic acid and 2-methyl-1-propylindole by method
C. From 0.20g (1.00mmol) of 4-ethyl-1-naphthoic acid
and 0.21g (1.20mmol) of 2-methyl-1-propylindole there
was obtained after chromatography (petroleum ether/
ether, 9:1) 0.192g (52%) of JWH-211 as a gum: 1H
NMR (300MHz, CDCl3) d 1.00 (t, J = 7.4Hz, 3H),
1.43 (t, J = 7.5Hz, 3H), 1.78–1.90 (m, 2H), 2.48 (s,
3H), 3.20 (q, J = 7.5Hz, 2H), 4.10 (t, J = 7.5Hz, 2H),
7.00 (d, J = 7.2Hz, 1H), 7.15–7.25 (m, 2H), 7.30–7.35
(m, 2H), 7.40–7.55 (m, 3H), 8.14 (d, J = 8.4Hz, 1H),
8.18 (d, J = 8.6Hz, 1H); 13C NMR (75.5MHz, CDCl3)
d 11.4, 12.5, 14.9, 22.9, 26.2, 44.8, 109.4, 115.1, 121.3,
121.8, 122.1, 123.8, 124.0, 125.8, 126.0, 126.3, 126.4,
127.1, 130.7, 132.1, 136.1, 138.8, 142.7, 145.4, 192.9;
MS (EI) m/z 355 (100), 338 (40), 326 (96), 298 (38);
HRMS Calcd for C25H25NO: 354.1858, Found
354.1852.
5.1.11. 1-Pentyl-3-(4-propyl-1-naphthoyl)indole, JWH-
182. JWH-182 was prepared from 4-propyl-1-naphthoic
acid and 1-pentylindole by method C. From 0.11g
(0.51mmol) of 4-propyl-1-naphthoic acid and 0.11g
(0.62mmol) of 1-pentylindole there was obtained after
chromatography (petroleum ether/ether, 9:1) 0.099g
(50%) of JWH-182 as a gum: 1H NMR (300MHz,
CDCl3) d 0.86 (t, J = 6.8Hz, 3H), 1.09 (t, J = 7.3Hz,
3H), 1.24–1.32 (m, 4H), 1.79–1.92 (m, 4H), 3.13 (t,
J = 7.7Hz, 2H), 4.07 (t, J = 7.2Hz, 2H), 7.35–7.44 (m,
5H), 7.46–7.50 (m, 2H), 7.52–7.60 (m, 2H), 8.13 (d,
J = 8.4Hz, 1H), 8.26 (d, J = 8.2Hz, 1H); 13C NMR
(75.5MHz, CDCl3) d 13.8, 14.3, 22.1, 23.8, 28.9, 29.5,
35.4, 47.1, 109.9, 117.6, 122.7, 122.9, 123.5, 124.0,
124.6, 125.7, 126.0, 126.1, 126.7, 127.0, 131.2, 132.2,
137.0, 137.5, 137.8, 141.0, 192.0; MS (EI) m/z 383
(100), 366 (63), 326 (75); HRMS Calcd for C27H29NO:
383.2249, Found 383.2243.
5.1.8. 2-Methyl-1-pentyl-3-(4-ethyl-1-naphthoyl)indole,
JWH-213. JWH-213 was prepared from 4-ethyl-1-
naphthoic acid and 2-methyl-1-pentylindole by method
C. From 0.20g (1.00mmol) of 4-ethyl-1-naphthoic acid
and 0.24g (1.20mmol) of 2-methyl-1-propylindole there
was obtained after chromatography (petroleum ether/
ether, 9:1) 0.205g (55%) of JWH-213 as a gum: 1H
NMR (300MHz, CDCl3) d 0.98 (t, J = 7.0Hz, 3H),
1.22–1.34 (t, J = 7.3Hz, 3H), 1.42–1.49 (m, 4H), 1.84–
1.94 (m, 2H), 2.56 (s, 3H), 3.28 (q, J = 7.5Hz, 2H),
4.20 (t, J = 7.5Hz, 2H), 7.10 (d, J = 7.3Hz, 1H), 7.27–
7.34 (m, 2H), 7.38–7.54 (m, 2H), 7.59–7.64 (m, 3H),
8.22 (d, J = 8.4Hz, 1H), 8.26 (d, J = 8.2Hz, 1H); 13C
NMR (75.5MHz, CDCl3) d 12.4, 13.8, 14.9, 22.3, 26.1,
29.0, 29.2, 43.2, 109.3, 115.0, 121.2, 121.7, 122.0,
123.8, 123.9, 125.7, 125.9, 126.2, 126.3, 127.1, 130.7,
132.0, 136.0, 138.8, 142.5, 145.2, 193.6; MS (EI) m/z
383 (100), 368 (59), 354 (71), 298 (43); HRMS Calcd
for C27H29NO: 383.2249, Found 383.2246.
5.1.12.
2-Methyl-1-propyl-3-(4-propyl-1-naphthoyl)-
indole, JWH-189. JWH-189 was prepared from 4-pro-
pyl-1-naphthoic acid and 2-methyl-1-propylindole by
method C. From 0.12g (0.56mmol) of 4-propyl-1-
naphthoic acid and 0.12g (0.67mmol) of 2-methyl-1-
propylindole there was obtained after chromatography
(petroleum ether/ether, 9:1) 0.12g (60%) of JWH-189
as a gum: 1H NMR (300MHz, CDCl3) d 0.97–1.08
(m, 6H), 1.80–1.88 (m, 4H), 2.48 (s, 3H), 3.13 (t,
J = 7.6Hz, 2H), 4.10 (t, J = 7.5Hz, 2H), 7.00 (d,
J = 7.6Hz, 1H), 7.15–7.25 (m, 2H), 7.30–7.38 (m, 2H),
7.40–7.56 (m, 3H), 8.13 (d, J = 8.5Hz, 1H), 8.25
(d, J = 8.3Hz, 1H); 13C NMR (75.5MHz, CDCl3) d
11.4, 12.9, 14.2, 22.9, 23.8, 35.4, 44.8, 109.4, 121.3,

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J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
122.0, 122.1, 122.9, 124.1, 125.2, 125.7, 126.0, 126.4,
127.4, 128.0, 130.9, 132.3, 136.0, 139.1, 141.1, 145.7,
192.9; MS (EI) m/z 369 (100), 352 (40), 326 (87); HRMS
Calcd for C26H27NO: 369.2093, Found 369.2088.
CDCl3) d 0.87 (t, J = 6.8Hz, 3H), 1.03 (t, J = 7.3Hz,
3H), 1.24–1.35 (m, 4H), 1.47–1.59 (m, 2H), 1.76–1.86
(m, 4H), 3.16 (t, J = 7.8Hz, 2H), 4.06 (t, J = 7.2Hz,
2H), 7.34–7.42 (m, 5H), 7.45–7.53 (m, 2H), 7.56–7.60
(m, 2H), 8.15 (d, J = 8.4Hz, 1H), 8.28 (d, J = 8.3Hz,
1H); 13C NMR (75.5MHz, CDCl3) d 13.8, 14.0, 22.1,
22.9, 28.8, 29.4, 32.9, 33.1, 47.0, 109.9, 117.6, 122.7,
122.9, 123.4, 124.0, 124.5, 125.7, 126.0, 126.1, 126.7,
127.0, 131.2, 132.1, 137.0, 137.4, 137.8, 141.3, 192.3;
MS (EI) m/z 397 (100), 380 (59), 340 (82); HRMS Calcd
for C28H31NO: 397.2406, Found 397.2400.
5.1.13.
2-Methyl-1-pentyl-3-(4-propyl-1-naphthoyl)-
indole, JWH-181. JWH-181 was prepared from 4-pro-
pyl-1-naphthoic acid and 2-methyl-1-pentylindole by
method C. From 0.11g (0.51mmol) of 4-propyl-1-
naphthoic acid and 0.12g (0.62mmol) of 2-methyl-1-
pentylindole there was obtained after chromatography
(petroleum ether/ether, 9:1) 0.11g (54%) of JWH-181
as a gum: 1H NMR (300MHz, CDCl3) d 0.93 (t,
J = 7.4Hz, 3H), 1.05 (t, J = 7.3Hz, 3H), 1.36–1.40 (m,
4H), 1.80–1.87 (m, 4H), 2.48 (s, 3H), 3.13 (t,
J = 7.6Hz, 2H), 4.12 (t, J = 7.6Hz, 2H), 7.00 (d,
J = 7.5Hz, 1H), 7.15–7.22 (m, 2H), 7.30–7.35 (m, 2H),
7.40–7.55 (m, 3H), 8.13 (d, J = 8.5Hz, 1H), 8.17
(d, J = 8.4Hz, 1H); 13C NMR (75.5MHz, CDCl3) d
12.5, 13.9, 14.2, 22.4, 23.8, 29.1, 29.3, 35.4, 43.3, 109.3,
115.1, 121.3, 121.8, 122.1, 124.1, 125.2, 125.6, 126.3,
126.4, 127.1, 130.8, 132.2, 136.0, 138.8, 141.0, 145.3,
193.8; MS (EI) m/z 397 (100), 382 (56), 354 (81); HRMS
Calcd for C28H31NO: 397.2406, Found 397.2394.
5.1.17. 2-Methyl-1-propyl-3-(4-butyl-1-naphthoyl)indole,
JWH-241. JWH-241 was prepared from 4-butyl-1-
naphthoic acid and 2-methyl-1-propylindole by method
C. From 0.18g (0.79mmol) of 4-butyl-1-naphthoic acid
and 0.16g (0.95mmol) of 2-methyl-1-propylindole there
was obtained after chromatography (petroleum ether/
ether, 9:1) 0.18g (62%) of JWH-241 as a gum: 1H
NMR (300MHz, CDCl3) d 0.97–1.03 (m, 6H), 1.44–
1.56 (m, 2H), 1.77–1.90 (m, 4H), 2.49 (s, 3H), 3.16 (t,
J = 7.7Hz, 2H), 4.13 (t, J = 7.9Hz, 2H), 7.02 (d,
J = 7.4Hz, 1H), 7.16–7.25 (m, 2H), 7.30–7.36 (m, 2H),
7.42–7.56 (m, 3H), 8.13 (d, J = 8.5Hz, 1H), 8.25
(d, J = 8.3Hz, 1H); 13C NMR (75.5MHz, CDCl3) d
11.4, 12.5, 14.0, 22.8, 22.9, 32.9, 33.1, 44.8, 109.4,
115.0, 121.3, 121.7, 122.1, 124.0, 125.0, 125.7, 125.9,
126.2, 126.4, 127.1, 130.8, 132.2, 136.1, 138.8, 141.3,
145.4, 193.7; MS (EI) m/z 383 (100), 366 (34), 326
(95); Calcd for C27H29NO: 383.2249, Found 383.2246.
5.1.14. 4-Butyl-1-naphthoic acid (17). Acid 17 was pre-
pared in a manner analogous to that employed for
4-ethyl-1-naphthoic acid: mp 136–137ꢁC (lit. mp 148–
1
148.5 ꢁC, Ref. 26); H NMR (300MHz, CDCl3) d 0.99
(t, J = 7.3Hz, 3H), 1.42–1.54 (m, 2H), 1.73–1.81 (m,
2H), 3.14 (t, J = 7.7Hz, 2H), 7.41 (d, J = 7.3Hz, 1H),
7.56–7.67 (m, 2H), 8.14 (d, J = 8.2Hz, 1H), 8.33 (d,
J = 7.5Hz, 1H), 9.15 (d, J = 8.2Hz, 1H); 13C NMR
(75.5MHz, CDCl3) d 14.0, 22.9, 32.8, 33.4, 123.9,
124.3, 124.9, 126.0, 126.6, 127.5, 131.6, 132.1, 132.3,
146.3, 172.9; MS (EI) m/z 228 (53), 185 (100), 157 (36).
5.1.18. 2-Methyl-1-pentyl-3-(4-butyl-1-naphthoyl)indole,
JWH-242. JWH-242 was prepared from 4-butyl-1-
naphthoic acid and 2-methyl-1-pentylindole by method
C. From 0.17g (0.75mmol) of 4-butyl-1-naphthoic acid
and 0.18g (0.89mmol) of 2-methyl-1-pentylindole there
was obtained after chromatography (petroleum ether/
ether, 9:1) 0.17g (56%) of JWH-242 as a gum: 1H
NMR (300MHz, CDCl3) d 0.92 (t, J = 6.9Hz, 3H),
1.00 (t, J = 7.3Hz, 3H), 1.39–1.45 (m, 4H), 1.47–1.55
(m, 2H), 1.74–1.84 (m, 4H), 2.48 (s, 3H), 3.16 (t,
J = 7.7Hz, 2H), 4.12 (t, J = 7.6Hz, 2H), 7.02 (t,
J = 7.4Hz, 1H), 7.16–7.26 (m, 2H), 7.32–7.36 (m, 2H),
7.40–7.56 (m, 3H), 8.14 (d, J = 8.5Hz, 1H), 8.18
(d, J = 8.5Hz, 1H); 13C NMR (75.5MHz, CDCl3) d
12.5, 13.9, 14.0, 22.4, 22.8, 29.1, 29.3, 32.9, 33.1, 43.3,
109.3, 121.3, 121.8, 122.1, 124.0, 125.1, 125.7, 125.9,
126.2, 126.4; MS (EI) m/z 411 (89), 396 (60), 354
(100); Calcd for C29H33NO: 411.2562, Found 411.2563.
5.1.15. 1-Propyl-3-(4-butyl-1-naphthoyl)indole, JWH-
239. JWH-239 was prepared from 4-butyl-1-naphthoic
acid and 1-propylindole by method C. From 0.18g
(0.79mmol) of 4-butyl-1-naphthoic acid and 0.15g
(0.95mmol) of 1-propylindole there was obtained after
chromatography (petroleum ether/ether, 9:1) 0.19g
(62%) of JWH-239 as a gum: 1H NMR (300MHz,
CDCl3) d 0.90 (t, J = 7.4Hz, 3H), 1.02 (t, J = 7.3Hz,
3H), 1.46–1.58 (m, 2H), 1.71–1.88 (m, 4H), 3.15 (t,
J = 7.8Hz, 2H), 4.04 (t, J = 7.1Hz, 2H), 7.35–7.43 (m,
5H), 7.46–7.50 (m, 2H), 7.52–7.60 (m, 2H), 8.14 (d,
J = 8.3Hz, 1H), 8.27 (d, J = 8.2Hz, 1H); 13C NMR
(75.5MHz, CDCl3) d 11.3, 14.0, 22.9, 23.1, 32.9, 33.1,
48.7, 109.9, 117.6, 122.7, 122.9, 123.5, 124.0, 124.5,
125.7, 126.0, 126.2, 126.7, 127.0, 131.2, 132.1, 137.0,
137.4, 137.9, 141.3, 192.3; MS (EI) m/z 369 (100), 352
(70), 340 (53); HRMS Calcd for C26H27NO: 369.2093,
Found 369.2094.
5.1.19. 1-Propyl-3-(7-methyl-1-naphthoyl)indole, JWH-
076 (method A). JWH-076 was prepared from 1-propyl-
indole and 7-methyl-1-naphthoyl chloride by method
B. From 0.186g (0.65mmol) of 3-(7-methyl-1-napht-
hoyl)indole and 0.5mL (5. 5mmol) of 1-bromopropane
there was obtained after chromatography (petroleum
ether/ethyl acetate, 1:3) 0.207g (97%) of JWH-076 as a
tan gum: 1H NMR (300MHz, CDCl3) d 0.90 (t,
J = 7.3Hz, 3H), 1.85 (q, J = 7.3Hz, 2H), 2.44 (s, 3H),
4.05 (t, J = 7.2Hz, 2H), 7.35–7.47 (m, 6H), 7.62 (d,
J = 6.8Hz, 1H), 7.81 (d, J = 8.3Hz, 1H), 7.92 (d,
J = 8.1Hz, 1H), 7.98 (s, 1H), 8.52 (t, J = 5.4Hz, 1H);
13C NMR (75.5MHz, CDCl3) d 11.3, 21.9, 23.1, 48.7,
5.1.16. 1-Pentyl-3-(4-butyl-1-naphthoyl)indole, JWH-
240. JWH-240 was prepared from 4-butyl-1-naphthoic
acid and 1-pentylindole by method C. From 0.17g
(0.75mmol) of 4-butyl-1-naphthoic acid and 0.17g
(0.89mmol) of 1-pentylindole there was obtained after
chromatography (petroleum ether/ether, 9:1) 0.17g
(58%) of JWH-240 as a gum: 1H NMR (300MHz,

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
105
110.0, 117.6, 122.8, 123.0, 123.5, 124.8, 125.9, 127.0,
127.9, 128.6, 129.7, 130.9, 132.0, 136.7, 137.0, 138.0,
138.4, 192.3; MS (EI) m/z 327 (82), 310 (43), 298 (58),
186 (100).
mp 117–120ꢁC (lit. mp 126ꢁC, Ref. 49): 1H NMR
(300MHz, CDCl3) d 1.37 (t, J = 7.5Hz, 3H), 2.90 (q,
J = 7.5Hz, 2H), 7.44–7.51 (m, 2H), 7.85 (d, J = 8.4Hz,
1H), 8.06 (d, J = 8.2Hz, 1H), 8.38 (dd, J = 1.0, 7.2Hz,
1H), 8.88 (s, 1H).
5.1.20. 7-Ethyl-1-naphthoic Acid (24). To a mixture of
9.56g of AlCl3 (64mmol) and 4.05mL of acetyl chloride
(57mmol) was added, with stirring, 21.3mL of 1,2-
dichloroethane. To this light brown solution was added
dropwise a solution of 10.0g (64mmol) of 2-ethylnaph-
thalene in 7.1mL of 1,2-dichloroethane. The reaction
mixture was allowed to stand at ambient temperature
for 18h, diluted with dichloromethane, and shaken with
dilute aqueous HCl. After washing with saturated aque-
ous NaHCO3 and water, the organic phase was dried
(MgSO4) and the solvents were removed in vacuo. Chro-
matography (petroleum ether/ethyl acetate, 95:5) gave
9.88g (86%) of 1-acetyl-7-ethylnaphthalene (26) as a col-
orless oil: 1H NMR (300MHz, CDCl3) d 1.33 (t,
J = 7.6Hz, 3H), 2.72 (s, 3H), 2.83 (q, J = 7.5Hz, 2H),
7.39–7.50 (m, 2H), 7.79 (d, J = 8.4Hz, 1H), 8.56 (s,
1H); 13C NMR (75.5MHz, CDCl3) d 15.5, 29.5, 30.0,
123.4, 123.8, 127.5, 128.3, 128.7, 130.3, 132.4, 132.7,
134.6, 144.3, 202.1.
5.1.21. 1-Propyl-3-(7-ethyl-1-naphthoyl)indole, JWH-
235. JWH-235 was prepared from 7-ethyl-1-naphthoic
acid by method B. From 0.150g (0.75mmol) of 7-
ethyl-1-naphthoic acid and 0.08g (0.50mmol) of 1-prop-
ylindole there was obtained 0.150g (88%) of JWH-235
as a pale brown oil after chromatography (petroleum
1
ether/ethyl acetate, 95:5): H NMR (300MHz, CDCl3)
d 0.83 (t, J = 7.3Hz, 3H), 1.21 (t, J = 7.5Hz, 3H),
1.70–1.83 (m, 2H), 2.72 (q, J = 7.5Hz, 2H), 3.95 (t,
J = 7.1Hz, 2H), 7.20–7.38 (m, 5H), 7.42 (d, J = 7.2Hz,
1H), 7.58 (dd, J = 7.2, 0.8Hz, 1H), 7.80 (d, J = 8.3Hz,
1H), 7.88 (d, J = 8.3Hz, 1H), 8.01 (s, 1H), 8.53–8.56
(m 1); 13C NMR (75.5MHz, CDCl3) d 11.2, 15.6, 22.9,
29.2, 48.6, 110.0, 117.4, 122.7, 122.8, 123.4, 123.5,
123.6, 125.9, 126.9, 127.3, 128.1, 129.6, 130.9, 132.2,
137.0, 138.0, 138.4, 142.8, 192.1; MS (EI) m/z 341
(100), 312 (80); HRMS Calcd for C24H23NO:
341.1760, Found 341.1779.
A solution of 8.7g (44mmol) of iodine in 15mL of pyr-
idine was added to 8.70g (44mmol) of 1-acetyl-7-ethyl-
naphthalene, and the solution was stirred at 100ꢁC for
30min. After cooling to ambient temperature the precip-
itated pyridinium salt was suspended in methanol and
collected by filtration. After drying in vacuo at 45ꢁC
there was obtained 23.5g of salt 27 as a brown solid,
which was added to 250mL of water without further
purification and 20g of solid NaOH were added. The
reaction mixture was heated at reflux for 2h, cooled to
ambient temperature and acidified with 10% aqueous
HCl to give 7.56g of acid 24 as dark purple crystals.
Recrystallization from aqueous methanol gave 5.74g
(65%) of product as a brown solid. For further purifica-
tion, to a solution of 1.0g of acid in 15mL of methanol
was added 3mL of H2SO4 and the reaction mixture was
heated at reflux for 2h. The reaction mixture was con-
centrated in vacuo, diluted with ether, washed with
water, and dried (MgSO4). The solvent was removed
in vacuo to give a brown oil, which was chromato-
graphed (petroleum ether/ethyl acetate, 95:5) to give
0.42g (42%) of ester as a colorless oil: 1H NMR
(300MHz, CDCl3) d 1.29 (t, J = 7.6Hz, 3H), 2.84 (q,
J = 7.3Hz, 2H), 3.98 (s, 3H), 7.39 (t, J = 7.6Hz, 1H),
7.38 (d, J = 8.0Hz, 1H), 7.77 (d, J = 8.4Hz, 1H), 7.94
(d, J = 8.1Hz, 1H), 8.07 (d, J = 7.7Hz, 1H), 8.74 (s,
1H); 13C NMR (75.5MHz, CDCl3) d 15.5, 29.5, 51.9,
123.5, 126.3, 127.2, 128.4, 130.2, 131.6, 132.3, 133.0,
143.9, 168.0.
5.1.22. 1-Pentyl-3-(7-ethyl-1-naphthoyl)indole, JWH-
234. JWH-234 was prepared from 7-ethyl-1-naphthoic
acid and 1-pentylindole by method B. From 0.150g
(0.75mmol) of 7-ethyl-1-naphthoic acid and 0.094g
(0.5mmol) of 1-pentylindole there was obtained after
chromatography (petroleum ether/ethyl acetate, 95:5)
0.100g (54%) of JWH-234 as a pale brown oil: 1H
NMR (300MHz, CDCl3) d 0.85 (t, J = 7.0Hz, 3H),
1.21–1.46 (m, 7H), 1.75–1.84 (m, 2H), 2.73 (q,
J = 7.6Hz, 2H), 4.05 (t, J = 7.2Hz, 2H), 7.34–7.41 (m,
5H), 7.45 (d, J = 7.2Hz, 1H), 7.61 (dd, J = 7.2, 1.0Hz,
1H), 7.83 (d, J = 8.3Hz, 1H), 7.92 (d, J = 8.3Hz, 1H),
8.00 (s, 1H), 8.51-8-.53 (m, 1H); 13C NMR (75.5MHz,
CDCl3) d 13.8, 15.7, 22.1, 28.7, 29.3, 29.5, 47.1, 109.9,
117.6, 122.8, 122.9, 123.5, 123.6, 123.7, 126.0, 127.0,
127.4, 128.1, 129.7, 131.0, 132.3, 137.0, 137.9, 138.5,
143.0, 192.2; MS (EI) m/z 369 (75), 352 (40), 312 (50),
207 (100); HRMS Calcd for C26H27NO: 369.2091,
Found 369.2093.
5.1.23. 2-Methyl-1-propyl-3-(7-ethyl-1-naphthoyl)indole,
JWH-236. JWH-236 was prepared from 7-ethyl-1-
naphthoic acid and 2-methyl-1-propylindole by method
B. From 0.150g (0.75mmol) of 7-ethyl-1-naphthoic acid
and 0.087g (0.5mmol) of 2-methyl-1-propylindole there
was obtained after chromatography (petroleum ether/
ethyl acetate, 95:5) 0.163g (92%) of JWH-236 as a pale
brown oil: 1H NMR (300MHz, CDCl3) d 0.98 (t,
J = 7.3Hz, 3H), 1.21 (t, J = 7.6Hz, 3H), 1.76–1.88 (m,
2H), 2.47 (s, 3H), 2.72 (q, J = 7.6Hz, 2H), 4.08 (t,
J = 7.4Hz, 2H), 7.00 (t, J = 7.3Hz, 1H), 7.17 (t,
J = 7.3Hz, 1H), 7.24 (d, J = 7.6Hz, 1H), 7.31 (d,
J = 8.2Hz, 1H), 7.36–7.51 (m, 2H), 7.52 (d, J = 6.0Hz,
1H), 7.83 (d, J = 8.2Hz, 1H), 7.92 (d, J = 8.2Hz, 1H),
7.96 (s, 1H); 13C NMR (75.5MHz, CDCl3) d 11.4,
12.5, 15.5, 22.9, 29.2, 44.8, 109.4, 114.9, 121.3, 121.8,
122.1, 123.4, 124.0, 126.0, 127.1, 127.3, 128.1, 129.8,
130.6, 132.3, 136.1, 139.7, 142.9, 145.5, 193.6; MS (EI)
To a suspension of 1.66g (8.4mmol) of ester in 50mL of
water was added 10g of KOH and the mixture was
heated at reflux for 18h. After acidification with conc.
HCl to pH5 the precipitated solid was filtered out to
give, after drying in vacuo, 1.32g (80%) of 7-ethyl-1-
naphthoic acid (24) as an off white solid, which was used
in subsequent steps without further purification. Recrys-
tallization from petroleum ether gave fine white needles:

106
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
m/z 355 (100), 338 (40); HRMS Calcd for C25H25NO:
355.1936, Found 355.1936.
5.1.27.
2-Methyl-1-propyl-3-(4-ethoxy-1-naphthoyl)-
indole, JWH-261. JWH-261 was prepared from 4-eth-
oxy-1-naphthoic acid and 2-methyl-1-propylindole by
method B. From 0.13g (0.6mmol) of 4-ethoxy-1-napht-
hoic acid and 0.087g (0.5mmol) of 2-methyl-1-propylin-
dole there was obtained after chromatography
(petroleum ether/ethyl acetate, 9:1) 0.17g (90%) of
JWH-261 as a gum: 1H NMR (300MHz, CDCl3) d
1.04 (t, J = 7.2Hz, 3H), 1.64 (t, J = 6.8Hz, 3H), 1.84–
1.91 (m, 2H), 2.54 (s, 3H), 4.11 (t, J = 7.2Hz, 2H),
4.29 (q, J = 6.8Hz, 2H), 6.82 (d, J = 7.9Hz, 1H), 7.10
(t, J = 7.5Hz, 1H), 7.24 (t, J = 7.2Hz, 1H), 7.30–7.44
(m, 2H), 7.55–7.58 (m, 2H), 7.65 (d, J = 7.9Hz, 1H),
8.38–8.41 (m, 1H), 8.47–8.50 (m, 1H); 13C NMR
(75.5MHz, CDCl3) d 11.3, 12.3, 14.6, 22.8, 44.6, 63.6,
103.2, 109.3, 115.1, 121.1, 121.4, 121.8, 122.1, 125.3,
125.4, 125.7, 127.1, 127.3, 128.4, 131.8, 132.0, 135.9,
144.6, 156.4, 193.0; HRMS Calcd for C25H25NO2:
368.3411, Found 368.3403.
5.1.24. 2-Methyl-1-pentyl-3-(7-ethyl-1-naphthoyl)indole,
JWH-262. JWH-262 was prepared from 7-ethyl-1-
naphthoic acid and 2-methyl-1-pentylindole by method
B. From 0.150g (0.75mmol) of 7-ethyl-1-naphthoic acid
and 0.100g (0.5mmol) of 1-pentylindole there was ob-
tained after chromatography (petroleum ether/ethyl ace-
tate, 95:5) 0.167g (87%) of JWH-262 as a pale brown oil:
1H NMR (300MHz, CDCl3) d 0.89 (t, J = 6.9Hz, 3H),
1.21 (t, J = 7.6Hz, 3H), 1.26–1.43 (m, 4H), 1.74–1.79
(m, 2H), 2.47 (s, 3H), 2.71 (q, J = 7.6Hz, 2H), 4.09 (t,
J = 7.5Hz, 2H), 6.99 (t, J = 7.3Hz, 1H), 7.16 (t,
J = 7.3Hz, 1H), 7.24 (d, J = 8.0Hz, 1H), 7.30 (d,
J = 8.0Hz, 1H), 7.36–7.48 (m, 2H), 7.52 (dd, J = 7.1,
1.2Hz, 1H), 7.83 (d, J = 8.4Hz, 1H), 7.91 (d,
J = 8.4Hz, 1H), 7.97 (s, 1H); 13C NMR (75.5MHz,
CDCl3) d 12.5, 13.9, 15.5, 22.3, 29.0, 29.3, 43.3, 53.3,
109.3, 114.9, 121.1, 121.7, 122.1, 123.4, 124.0, 126.0,
127.1, 127.2, 128.1, 129.7, 130.5, 132.5, 135.9, 139.6,
142.9, 145.4, 193.6; MS (EI) m/z 383 (100), 368 (50),
297 (50); HRMS Calcd for C27H29NO: 382.2175, Found
382.2175.
5.1.28.
2-Methyl-1-pentyl-3-(4-ethoxy-1-naphthoyl)-
indole, JWH-260. JWH-260 was prepared from 4-eth-
oxy-1-naphthoic acid and 2-methyl-1-pentylindole by
method B. From 0.13g (0.6mmol) of 4-ethoxy-1-napht-
hoic acid and 0.10g (0.5mmol) of 2-methyl-1-pentylin-
dole there was obtained after chromatography
(petroleum ether/ethyl acetate, 9:1) 0.18g (90%) of
JWH-260 as a gum: 1H NMR (300MHz, CDCl3) d
0.89 (t, J = 6.9Hz, 3H), 1.34–1.36 (m, 4H), 1.56 (t,
J = 6.9Hz, 3H), 1.74–1.81 (m, 2H), 2.47 (s, 3H), 4.07
(t, J = 7.4Hz, 2H), 4.22 (q, J = 6.9Hz, 2H), 6.75 (d,
J = 7.9Hz, 1H), 6.99 (t, J = 7.5Hz, 1H), 7.15 (t,
J = 8.1Hz, 1H), 7.22–7.30 (m, 2H), 7.45–7.50 (m, 2H),
7.55 (d, J = 7.9Hz, 1H), 8.26–8.29 (m, 1H), 8.36–8.39
(m, 1H); 13C NMR (75.5MHz, CDCl3) d 12.4, 13.9,
14.7, 22.3, 29.0, 29.3, 43.2, 63.8, 103.2, 109.3, 112.2,
115.2, 121.4, 121.9, 122.1, 125.3, 125.5, 125.7, 127.2,
127.3, 128.5, 131.8, 132.1, 135.9, 144.6, 156.5, 193.1;
HRMS Calcd for C27H29NO2: 399.2193, Found
399.2198.
5.1.25. 1-Propyl-3-(4-ethoxy-1-naphthoyl)indole, JWH-
259. JWH-259 was prepared from 4-ethoxy-1-naphthoic
acid and 1-propylindole by method B. From 0.13g
(0.6mmol) of 4-ethoxy-1-naphthoic acid and 0.080g
(0.5mmol) of 1-propylindole there was obtained after
chromatography (petroleum ether/ethyl acetate, 9:1)
0.15g (86%) of JWH-259 as a gum: 1H NMR
(300MHz, CDCl3) d 0.85 (t, J = 7.3Hz, 3H), 1.55 (t,
J = 6.9Hz, 3H), 1.75–1.82 (m, 2H), 3.97 (t, J = 7.1Hz,
2H), 4.20 (q, J = 6.9Hz, 2H), 6.74 (d, J = 7.9Hz, 1H),
7.29–7.37 (m, 4H), 7.45–7.47 (m, 2H), 7.60 (d,
J = 7.9Hz, 1H), 8.29–8.32 (m, 1H), 8.34–8.38 (m, 1H),
8.46–8.48 (m, 1H); 13C NMR (75.5MHz, CDCl3) d
11.2, 14.7, 23.0, 48.5, 63.8, 102.7, 109.9, 117.6, 122.1,
122.5, 122.7, 123.3, 125.4, 125.5, 125.6, 125.7,
127.2, 127.9, 131.1, 132.1, 136.9, 137.4, 156.3,
191.7; HRMS Calcd for C24H23NO2: 357.1725, Found
357.1728.
5.1.29. 1-Propyl-3-(2-methoxy-1-naphthoyl)indole, JWH-
265 (30). Indole 30 was prepared from 2-methoxy-1-
naphthoic acid and 1-propylindole by method B. From
0.150g (0.75mmol) of 2-methoxy-1-naphthoic acid and
0.075g (0.47mmol) of 1-propylindole there was ob-
tained after chromatography (petroleum ether/ethyl
acetate, 7:3) 0.113g (70%) of 1-propyl-3-(2-methoxy-
1-naphthoyl)indole (30) as white crystals: mp 117–
5.1.26. 1-Pentyl-3-(4-ethoxy-1-naphthoyl)indole, JWH-
258. JWH-258 was prepared from 4-ethoxy-1-naphthoic
acid and 1-pentylindole by method B. From 0.13g
(0.6mmol) of 4-ethoxy-1-naphthoic acid and 0.094g
(0.5mmol) of 1-pentylindole there was obtained after
chromatography (petroleum ether/ethyl acetate, 9:1)
0.17g (90%) of JWH-258 as a gum: 1H NMR
(300MHz, CDCl3) d 0.83 (t, J = 6.6Hz, 3H), 1.26–1.29
(m, 4H), 1.56 (t, J = 6.9Hz, 3H), 1.75–1.82 (m, 2H),
4.03 (t, J = 7.1Hz, 2H), 4.22 (q, J = 6.9Hz, 2H), 6.77
(d, J = 7.9Hz, 1H), 7.22–7.38 (m, 4H), 7.47–7.50 (m,
2H), 7.62 (d, J = 7.9Hz, 1H), 8.29–8.33 (m, 1H), 8.35–
8.39 (m, 1H), 8.46–8.48 (m, 1H); 13C NMR
(75.5MHz, CDCl3) d 13.8, 14.7, 22.1, 28.8, 29.4, 46.9,
63.9, 102.8, 109.9, 117.6, 122.1, 122.5, 122.8, 123.3,
125.4, 125.5, 125.7, 125.8, 127.2, 127.9, 131.1, 132.1,
136.9, 137.3, 156.3, 191.7; HRMS Calcd for
C26H27NO2: 385.2038, Found 385.2042.
119ꢁC; 1H NMR (300MHz, CDCl3)
d 0.77 (t,
J = 7.4Hz, 3H), 1.70 (sept, J = 7.2Hz, 2H), 3.79 (s,
3H), 3.86 (t, J = 6.8Hz, 2H), 7.21–7.31 (m, 7H), 7.68–
7.71 (m, 1H), 7.75–7.78 (m, 1H), 7.87 (d, J = 9.0Hz,
1H), 8.44 (s, 1H); 13C NMR (75.5MHz, CDCl3) d
11.0, 22.8, 48.4, 56.5, 109.9, 113.4, 117.9, 122.5, 122.6,
123.2, 123.7, 124.5, 125.1, 126.3, 126.8, 127.7, 128.6,
130.2, 131.8, 136.9, 137.9, 153.3, 190.7; MS (EI) m/z
343 (100), 326 (50), 172 (43); HRMS Calcd for
C23H21NO2: 343.1572, Found 343.1577.
5.1.30. 1-Pentyl-3-(2-methoxy-1-naphthoyl)indole, JWH-
267 (32). Indole 32 was prepared from 2-methoxy-1-
naphthoic acid and 1-pentylindole by method B. From

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
107
0.150 (0.75mmol) of 2-methoxy-1-naphthoic acid and
0.090g (0.48mmol) of 1-pentylindole there was obtained
after chromatography (petroleum ether/ethyl acetate,
2.34 (s, 3H), 3.41 (s, 3H), 3.54 (t, J = 8.7Hz, 2H), 6.89
(br s, 1H), 6.95–7.12 (m, 6H), 7.60 (d, J = 7.3Hz, 1H),
7.64 (d, J = 10.2Hz, 1H), 7.90 (d, J = 8.2Hz, 1H); 13C
NMR (75.5MHz, CDCl3) d 13.9, 22.3, 29.0, 29.2, 43.2,
56.7, 109.3, 113.6, 116.0, 122.1, 122.2, 122.4, 123.9,
124.2, 125.2, 126.3, 127.0, 127.8, 128.9, 130.2, 131.2,
138.6, 152.9, 191.3; MS (EI) m/z 385 (34), 354 (100),
185 (46); HRMS Calcd for C26H27NO2: 385.2042,
Found 385.2040.
1
7:3) 0.107g (60%) of 32 as a viscous yellow gum: H
NMR (300MHz, CDCl3) d 0.81 (t, J = 6.9Hz, 3H),
1.18–1.26 (m, 4H), 1.75 (quintet, J = 7.1Hz, 2H), 3.86
(s, 3H), 3.99 (t, J = 7.2Hz, 2H), 7.24–7.37 (m, 7H),
7.68–7.72 (m, 1H), 7.80–7.83 (m, 1H), 7.92 (d,
J = 9.1Hz, 1H), 8.41 (s, 1H); 13C NMR (75.5MHz,
CDCl3) d 13.8, 22.0, 28.7, 29.2, 47.0, 56.5, 109.9,
113.4, 118.0, 122.6, 122.7, 123.2, 123.8, 124.6, 125.2,
126.4, 126.8, 127.7, 128.6, 130.2, 131.8, 136.9, 137.9,
153.4, 190.8; MS (EI) m/z 37 (100), 354 (61), 200 (55);
HRMS Calcd for C25H25NO2: 371.1885, Found
371.1876.
5.1.33. 6-Methoxy-1-naphthoic acid (35). To a solution
of 2.3g (13.2mmol) of 6-methoxy-1-naphthol40,41 in
50mL of pyridine was added dropwise at 0ꢁC 2.6mL
(15.5mmol) of trifluoromethanesulfonic anhydride.
The solution was warmed to ambient temperature, stir-
red for 18h, quenched with water and extracted with
ether. The combined ethereal extracts were washed with
10% aqueous HCl until the aqueous solution was acidic.
The solution was dried (MgSO4) and the solvent was re-
moved in vacuo. The residue was chromatographed
(petroleum ether/ethyl acetate, 12:1) to give 3.4g (84%)
of triflate as a yellow oil, which was used in the subse-
quent step without further purification: 1H NMR
(300MHz, CDCl3) d 3.92 (s, 3H), 7.16 (d, J = 2.4Hz,
1H), 7.27 (dd, J = 8.7, 2.4Hz, 2H), 7.41 (t, J = 8.1Hz,
1H), 7.95 (d, J = 9.0Hz, 1H); 13C NMR (75.5MHz,
CDCl3) d 55.4, 106.0 115.3, 116.6, 120.7, 120.9, 121.6,
122.4, 125.8, 127.2, 136.5, 145.8, 158.7; MS (EI) m/z
306 (25), 173 (55), 145 (100).
5.1.31.
2-Methyl-1-propyl-3-(2-methoxy-1-naphthoyl)-
indole, JWH-266 (31). Indole 31 was prepared from 2-
methoxy-1-naphthoic acid and 2-methyl-1-propylindole
by method B. From 0.150g (0.75mmol) of 2-methoxy-
1-naphthoic acid and 0.086g (0.50mmol) of 2-methyl-
1-propylindole there was obtained after chromatogra-
phy (petroleum ether/ethyl acetate, 7:3) 0.100g (58%)
of 31 as a yellow solid: mp 124–125ꢁC; 1H NMR
(300MHz, CDCl3) d 0.86 (t, J = 7.3Hz, 3H), 1.57–1.73
(m, 2H), 3.73 (s, 3H), 3.92 (t, J = 6.7Hz, 2H), 7.08 (s,
3H), 7.17–7.30 (m, 7H), 7.58–7.60 (m, 1H), 7.74–7.76
1
(m, 1H), 7.87 (d, J = 9.1Hz, 1H); H NMR (500MHz,
DMSO-d6, 25ꢁC) d 0.88 (br s, 3H), 1.61–1.78 (m, 2H),
3.78 (s, 3H), 4.08–4.23 (m, 2H), 7.13 (br s, 1H), 7.24–
7.64 (m, 6H), 7.93–7.98 (m, 1H), 8.10 (d, J = 9.1
Hz, 1H); 1H NMR (500MHz, DMSO-d6, 125ꢁC) d
0.88 (t, 6.8Hz, 3H), 1.71–1.80 (m, 2H), 2.36 (s, 3H),
3.80 (s, 3H), 4.17 (t, J = 7.4Hz, 2H), 6.95
(t, J = 7.8Hz, 1H); 7.14 (td, J = 0.5, 8.2Hz, 1H), 7.32–
7.39 (m, 2H), 7.47–7.58 (m, 4H), 7.91–7.96 (m,
1H), 8.06 (d, J = 9.2Hz, 1H); 13C NMR (75.5MHz,
CDCl3) d 11.0, 22.8, 44.4, 56.4, 109.3, 115.2, 121.4,
121.9, 122.2, 123.7, 123.9, 125.2, 126.3, 126.8, 127.7,
128.7, 130.0, 131.0, 135.9, 145.7, 152.8, 191.4; MS (EI)
m/z 357 (44), 326 (100); HRMS Calcd for C24H23NO2:
357.1729, Found 357.1734.
To a solution of 0.96g (3.18mmol) of 6-methoxy-1-
naphthyl trifluoromethanesulfonate in 30mL of DMF
was added 0.034g (0.15mmol) of Pd(OAc)2, 0.040g
(0.010mmol) of 1,3-bis(diphenylphosphino)propane
and 1.20g of triethylamine. The mixture was flushed
with carbon monoxide for 25min, 3.1mL of 96% formic
acid was added dropwise and the reaction was stirred at
ambient temperature for 6h under an atmosphere of
CO, diluted with water, and extracted with ethyl acetate.
The organic extracts were washed with five portions of
brine, followed by two portions of aqueous NaHCO3.
The bicarbonate extracts were combined, cautiously
neutralized with 10% aqueous HCl, and extracted with
ether. The ethereal extracts were washed with water,
dried (MgSO4), and the solvent was removed in vacuo
to give 0.42g (65%) of acid 35 as a yellow powder.
Recrystallization from ethyl acetate/petroleum ether
gave pale yellow needles: mp 185–186ꢁ (lit. mp 180–
180.5ꢁC, Ref. 36); 1H NMR (300MHz, CDCl3) d
3.89 (s, 3H), 7.29 (dd, J = 6.9, 2.4Hz, 1H), 7.41
(d, J = 2.4Hz, 1H), 7.53 (t, J = 7.8Hz, 1H), 7.98 (d,
J = 6.1Hz, 1H), 8.05 (d, J = 8.1Hz, 1H), 8.79 (d,
J = 9.1Hz, 1H); 13C NMR (75.5MHz, CDCl3) d 55.2,
106.7, 120.0, 125.4, 126.1, 127.1, 127.5, 127.6, 131.8,
135.2, 157.1, 168.8; MS (EI) m/z 202 (100), 159 (35),
109 (50).
5.1.32.
2-Methyl-1-pentyl-3-(2-methoxy-1-naphthoyl)-
indole, JWH-267 (33). Indole 33 was prepared from 2-
methoxy-1-naphthoic acid and 2-methyl-1-pentylindole
by method B. From 0.150g (0.75mmol) of 2-methoxy-
1-naphthoic acid and 0.094g (0.47mmol) of 2-methyl-
1-pentylindole there was obtained after chromatography
(petroleum ether/ethyl acetate, 7:3) 0.109g (60%) of 33
1
as a yellow solid: mp 39–40ꢁC; H NMR (300MHz,
CDCl3) d 0.81 (t, J = 7.0Hz, 3H), 1.35–1.36 (m, 4H),
1.59–1.63 (m, 2H), 3.83 (s, 3H), 4.08 (t, J = 7.0Hz,
2H), 7.15 (s, 3H), 7.25–7.38 (m, 7H), 7.64–7.67 (m,
1H), 7.80–7.84 (m, 1H), 7.94 (d, J = 9.0Hz, 1H); 2-
Methyl-1-pentyl-3-(2-methoxy-1-naphthoyl)indole
at
25; 1H NMR (500MHz, toluene-d8, 25ꢁC) d 0.72 (t,
J = 7.4Hz, 3H), 0.87–096 (m, 2H), 0.96–1.07 (m, 2H),
1.18–1.27 (m, 2H), 2.15–2.74 (br, 3H), 3.32 (s, 3H),
3.41 (t, J = 6.85Hz, 2H), 6.88–7.25 (m, 7H), 7.60–7.64
(m, 1H), 7.65 (d, J = 9.2Hz, 1H), 7.97 (d, J = 7.8Hz,
5.1.34. 1-Propyl-3-(6-methoxy-1-naphthoyl)indole, JWH-
163 (method D). To a solution of 0.18g (0.90mmol) of 6-
methoxy-1-naphthoic acid (35) in 10mL of dichloro-
methane was added dropwise 0.44mL (5.0mmol) of
oxalyl chloride. The solution was stirred at room
temperature for 1h, then heated at reflux for 1h. After
1
1H); H NMR (500MHz, toluene-d8, 100ꢁC) d 0.72 (t,
J = 7.4Hz, 3H), 0.97–1.11 (m, 4H), 1.30–1.39 (m, 2H),

108
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
cooling, the solvent and residual oxalyl chloride were re-
moved in vacuo. The residue was dissolved in 5mL of
toluene and added to a solution of 0.20g (1.3mmol) of
1-propylindole in 4mL of toluene at 0ꢁC. To this solu-
tion was added dropwise 0.82mL (1.5mmol) of 1.8M
EtAlCl2. The mixture was allowed to warm to ambient
temperature and stirred for 18h. After quenching with
water, the reaction mixture was extracted with ether.
The ethereal extracts were washed with water, dried
(MgSO4) and the solvent was removed in vacuo. The
residue was chromatographed (petroleum ether/ethyl
acetate, 8:1) to give 0.19g of JWH-163 as a colorless
5.1.37.
2-Methyl-1-pentyl-3-(6-methoxy-1-naphthoyl)-
indole, JWH-153. JWH-153 was prepared from 6-meth-
oxy-1-naphthoic acid and 2-methyl-1-pentylindole by
method D. From 0.20g (1.0mmol) of acid and 0.24g
(1.2mmol) of 2-methyl-1-pentylindole there was ob-
tained after chromatography (petroleum ether/ethyl ace-
tate, 12:1) 0.23g (60%) of JWH-153: mp 114.5–116ꢁC;
1H NMR (300MHz, CDCl3) d 0.90 (t, J = 6.9Hz, 3H),
1.35–1.38 (m, 4H), 1.74–1.79 (m, 2H), 2.46 (s, 3H),
3.92 (s, 3H), 4.10 (t, J = 7.6Hz, 2H), 6.98 (t,
J = 6.6Hz, 1H), 7.08 (dd, J = 9.3, 2.7Hz, 1H), 7.13–
7.20 (m 3), 7.29 (d, J = 8.4Hz, 1H), 7.39–7.48 (m, 2H),
7.84 (d, J = 7.8Hz, 1H), 8.98 (d, J = 9.0Hz, 1H); 13C
NMR (75.5MHz, CDCl3) d 12.4, 13.8, 22.3, 29.0, 29.3,
43.3, 55.2, 106.1, 109.4, 114.9, 119.5, 121.2, 121.8,
122.1, 123.4, 125.6, 125.7, 127.1, 127.2, 128.7, 135.1,
136.0, 140.4, 145.4, 157.7, 193.4; Anal. Calcd for
C26H27NO2: C, 81.01; H, 7.06; N, 3.63; Found: C,
80.80; H, 7.18; N, 3.62.
1
solid: mp 139–140ꢁC; H NMR (300MHz, CDCl3) d
0.87 (t, J = 7.3Hz, 3H), 1.81 (sextet, J = 7.3Hz, 2H),
3.91 (s, 3H), 4.01 (t, J = 7.2Hz, 2H), 7.12 (dd, J = 9.0,
2.5Hz, 1H), 7.18 (d, J = 2.54Hz, 1H), 7.30–7.39 (m,
4H), 7.44–7.52 (m, 2H), 7.82 (dd, J = 7.5, 1.6Hz, 1H),
8.09 (d, J = 9.0Hz, 1H), 8.47–8.50 (m, 1H); 13C NMR
(75.5MHz, CDCl3) d 11.3, 23.0, 48.7, 55.2, 106.0,
110.0, 117.4, 119.3, 122.7, 122.8, 123.5, 123.6, 125.1,
126.1, 126.9, 127.5, 128.7, 135.1, 137.0, 138.0,
139.0, 157.7, 192.1; Anal. Calcd for C23H21NO2: C,
80.44; H, 6.16; N, 4.08; Found: C, 80.30; H, 6.17; N,
3.99.
5.1.38. 7-Methoxy-1-naphthoic acid (36). The trifluoro-
methanesulfonate ester of 7-methoxy-1-naphthol was
prepared by the procedure employed for the preparation
of the triflate of 6-methoxy-1-naphthol. From 2.30g
(15.5mmol) of 7-methoxy-1-naphthol (40)40,41 there
was obtained after chromatography (petroleum ether/
ethyl acetate, 12:1) 3.40g (84%) of triflate as a colorless
5.1.35. 1-Pentyl-3-(6-methoxy-1-naphthoyl)indole, JWH-
166. JWH-166 was prepared from 6-methoxy-1-naph-
thoic acid and 1-pentylindole by method D. From
0.19g (0.9mmol) of acid and 0.24g (1.3mmol) of 1-pent-
ylindole there was obtained after chromatography
(petroleum ether/ethyl acetate, 8:1) 0.29g (81%) of
JWH-166 as an oil: 1H NMR (300MHz, CDCl3) d
0.85 (t, J = 6.9Hz, 3H), 1.23–1.33 (m, 4H), 1.75–1.85
(m, 2H), 3.98 (s, 3H), 4.05 (t, J = 7.3Hz, 2H), 7.12
(dd, J = 9.1, 2.5Hz, 1H), 7.18 (d, J = 2.5Hz, 1H),
7.33–7.40 (m, 4H), 7.47–7.52 (m, 2H), 7.83 (dd,
J = 7.4, 1.9Hz, 1H), 8.10 (d, J = 9.1Hz, 1H), 8.45–8.48
(m, 1H); 13C NMR (75.5MHz, CDCl3) d 13.8, 22.1,
28.9, 29.4, 47.1, 55.3, 106.1, 110.0, 117.5, 119.4, 122.8,
122.9, 123.5, 123.7, 125.1, 126.2, 127.0, 127.6, 128.7,
135.1, 137.0, 137.8, 139.0, 157.7, 192.1; MS (EI)
m/z 371 (90), 354 (75), 314 (65), 214 (100);
HRMS Calcd for C25H25NO2: 371.1885, Found
371.1885.
1
oil: H NMR (300MHz, CDCl3) d 3.91 (s, 3H), 7.16 (d,
J = 2.4Hz, 1H), 7.27 (dd, J = 8.7, 2.4Hz, 2H), 7.41 (t,
J = 8.1Hz, 1H), 7.71 (d, J = 8.2Hz, 1H), 7.95 (d,
J = 9.0Hz, 1H); 13C NMR (75.5MHz, CDCl3) 55.4,
106.0, 115.3, 116.6, 120.7, 120.9, 121.6, 122.4, 125.8,
127.2, 136.5, 145.8, 158.7; MS (EI) m/z 306 (25), 173
(55), 145 (100).
Acid 36 was prepared from 7-methoxy-1-naphthyl tri-
fluoromethanesulfonate by the procedure used for the
preparation of acid 35. From 0.96g (3.18mmol) of tri-
flate there was obtained, after recrystallization from
ethyl acetate/petroleum ether, 0.35g (54%) of acid 36:
1
mp 185–186ꢁ (lit. mp 169–170ꢁC Ref. 37); H NMR
(300MHz, CDCl3) d 3.89 (s, 3H), 7.29 (dd, J = 6.9,
2.4Hz, 1H), 7.41 (d, J = 2.4Hz, 1H), 7.53 (t,
J = 7.8Hz, 1H), 7.98 (d, J = 6.1Hz, 1H), 8.05 (d,
J = 8.1Hz, 1H), 8.79 (d, J = 9.1Hz, 1H); 13C NMR
(75.5MHz, CDCl3) d 55.2, 106.7, 120.0, 125.4, 126.1,
127.1, 127.5, 127.6, 131.8, 135.2, 157.1, 168.8; MS (EI)
m/z 202 (100), 159 (35), 109 (50).
5.1.36.
2-Methyl-1-propyl-3-(6-methoxy-1-naphthoyl)-
indole, JWH-151 (42). Indole 42 was prepared from 6-
methoxy-1-naphthoic acid and 2-methyl-1-propylindole
by method D. From 0.19g (0.9mmol) of acid and
0.22g (1.3mmol) of 2-methyl-1-propylindole there was
obtained after chromatography (petroleum ether/ethyl
acetate, 8:1) 0.19g (56%) of 42 as an oil: 1H NMR
(300MHz, CDCl3) d 0.99 (t, J = 7.5Hz, 3H), 1.79–1.86
(m, 2H), 2.47 (s, 3H), 3.92 (s, 3H), 4.09 (t, J = 7.5Hz,
2H), 6.99 (t, J = 7.3Hz, 1H), 7.09 (dd, J = 9.0, 2.7Hz,
1H), 7.14–7.20 (m, 3H), 7.30 (d, J = 7.8Hz, 1H), 7.40–
7.49 (m 2), 7.85 (d, J = 7.5Hz, 1H), 8.00 (d,
J = 9.0Hz, 1H); 13C NMR (75.5MHz, CDCl3) d 11.4,
12.5, 22.9, 44.8, 55.2, 106.1, 109.4, 114.9, 119.5, 121.2,
121.8, 122.1, 123.4, 125.7, 127.1, 127.2, 128.7, 135.2,
136.1, 140.5, 145.5, 157.7, 193.5; MS (EI) m/z 357
(100), 340 (40), 207 (98); HRMS Calcd for
C24H23NO2: 357.1729, Found 357.1721.
5.1.39. 1-Propyl-3-(7-methoxy-1-naphthoyl)indole JWH-
165. JWH-165 was prepared from 7-methoxy-1-naph-
thoic acid and 1-propylindole by method D. From
0.18g (0.9mmol) of acid and 0.24g (1.2mmol) of 1-
propylindole there was obtained after chromatography
(petroleum ether/ethyl acetate, 8:1) 0.19g (64%) of
JWH-165: 1H NMR (300MHz, CDCl3) d 0.90 (t,
J = 8.1Hz, 3H), 1.85 (q, J = 7.2Hz, 2H), 3.82 (s, 3H),
4.05 (t, J = 7.2Hz, 2H), 7.17 (dd, J = 8.9, 2.4Hz, 1H),
7.24–7.41 (m, 5H), 7.61–7.65 (m, 2H), 7.78 (d,
J = 8.9Hz, 1H), 7.88 (d, J = 8.1Hz, 1H), 8.47–8.50 (m,
1H); 13C NMR (75.5MHz, CDCl3) d 11.3, 23.1, 48.7,
55.3, 103.9, 110.0, 117.5, 119.4, 122.1, 122.7, 122.9,
123.5, 127.1, 129.4, 129.6, 130.0, 132.1, 137.0, 137.4,

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
109
137.8, 158.4, 192.2; MS (EI) m/z 343 (100), 326 (60), 314
(55), 207 (85); HRMS Calcd for C23H21NO2: 343.1572,
Found 343.1581.
CP 55,940 was provided by Pfizer (Groton, CT).
[3H]CP 55,940 was purchased from NEN Life Science
Products, Inc. (Boston, MA). Lipofectamine reagent
was purchased from Life Technologies (Gaithersburg,
MD). Human CB2 cDNA was provided by Dr. Sean
Munro (MRC Lab, Cambridge, UK). DMEM and
geneticin was purchased from (GIBCO BRL, Grand
Island, NY). Fetal clone II was purchased from Hyclone
Laboratories, Inc. (Logan, UT). Aquasil was purchased
from Pierce (Rockford, IL). GF/C glass-fiber filters
(2.4cm) were purchased from Baxter (McGaw Park,
IL). Polyethylenimine and bovine serum albumin were
purchased from Sigma Chemical Co. (St. Louis, MO).
Scintillation vials and Budget Solve scintillation
fluid were purchased from RPI Corp. (Mount Prospect,
IL).
5.1.40. 1-Pentyl-3-(7-methoxy-1-naphthoyl)indole, JWH-
164. JWH-164 was prepared from 7-methoxy-1-naph-
thoic acid and 1-pentylindole by method D. From
0.19g (1.0mmol) of acid and 0.24g (1.2mmol) of 1-pent-
ylindole there was obtained after chromatography
(petroleum ether/ethyl acetate, 8:1) 0.21g (66%) of
JWH-164: 1H NMR (300MHz, CDCl3) d 0.83 (t,
J = 7.5Hz, 3H), 1.18–1.32 (m, 4H), 1.77–1.86 (m, 2H),
3.82 (s, 3H), 4.08 (t, J = 7.2Hz, 2H), 7.18 (dd, J = 9.0,
2.5Hz, 1H), 7.34–7.42 (m, 5H), 7.61–7.65 (m, 2H), 7.79
(d, J = 9.0Hz, 1H), 7.89 (d, J = 8.1Hz, 1H), 8.46–8.51
(m, 1H); 13C NMR (75.5MHz, CDCl3) d 13.8, 22.1,
28.9, 29.5, 47.1, 55.3, 103.9, 110.0, 117.5, 119.4, 122.1,
122.2, 122.7, 122.9, 123.5, 127.1, 129.4, 129.6, 130.0,
132.1, 137.0, 137.4, 137.7, 158.4, 192.2; MS (EI) m/z
371 (100), 314 (55), 214 (45), 207 (65);
HRMS Calcd for C25H25NO2: 371.1885, Found 371.1893.
5.2.2. Development of hCB2-CHO cell line. Chinese
hamster ovary cells were maintained in DulbeccoÕs mod-
ified EagleÕs medium (DMEM) with 10% fetal clone II
and 5% CO2 at 37ꢁC in a Forma incubator. Cell lines
were created by transfection of CB2pcDNA3 into
CHO cells by the Lipofectamine reagent. Stable trans-
formants were selected in growth medium containing
geneticin (1mg/mL, reagent). Colonies of about 500 cells
were picked (about two weeks post-transfection) and al-
lowed to expand, then tested for expression of receptor
mRNA by northern blot analysis. Cell lines containing
moderate to high levels of receptor mRNA were tested
for receptor binding properties. Transfected cell lines
were maintained in DMEM with 10% fetal clone II plus
0.3–0.5mg/mL geneticin and 5% CO2 at 37ꢁC in a For-
ma incubator.
5.1.41.
2-Methyl-1-propyl-3-(7-methoxy-1-naphthoyl)-
indole, JWH-160. JWH-160 was prepared from 7-meth-
oxy-1-naphthoic acid and 2-methyl-1-propylindole by
method D. From 0.18g (0.9mmol) of acid and 0.24g
(1.2mmol) of 2-methyl-1-propylindole there was obtained
after chromatography (petroleum ether/ethyl acetate, 8:1)
0.20g (66%) of JWH-160 as a viscous oil: 1H NMR
(300MHz, CDCl3) d 0.99 (t, J = 7.3Hz, 3H), 1.77–1.90
(m, 2H), 2.50 (s, 3H), 3.79 (s, 3H), 4.10 (t, J = 7.5Hz,
2H), 7.03 (t, J = 7.8Hz, 1H), 7.16–7.24 (m, 3H), 7.32 (t,
J = 7.1Hz, 2H), 7.54–7.60 (m, 2H), 7.80 (d, J = 8.9Hz,
1H), 7.90 (d, J = 7.8Hz, 1H); 13C NMR (75.5MHz,
CDCl3) d 11.4, 12.5, 22.9, 44.8, 55.2, 103.7, 109.4, 115.3,
119.3, 121.2, 121.7, 122.1, 122.6, 127.2, 127.4, 129.5,
129.7, 130.1, 131.7, 136.1, 138.5, 145.1, 158.5, 193.8; MS
(EI) m/z 357 (100), 340 (40), 300 (15); HRMS Calcd for
C24H23NO2: 357.1729, Found 357.1720.
5.2.3. Membrane preparation. hCB2-CHO cells were har-
vested in phosphate-buffered saline containing 1mM
EDTA and centrifuged at 500g. Cell pellets (for CB2)
or whole rat brains (for CB1) were homogenized in
10mL of solution A (50mM Tris–HCl, 320mM sucrose,
2mM EDTA, 5mM MgCl2, pH7.4). The homogenate
was centrifuged at 1600g (10min), the supernatant
saved, and the pellet washed three times in solution A
with subsequent centrifugation. The combined super-
natants were centrifuged at 100,000g (60min). The (P2
membrane) pellet was resuspended in 3mL of buffer B
(50mM Tris–HCl, 1mM EDTA, 3mM MgCl2, pH7.4)
to yield a protein concentration of approximately
1mg/mL. The tissue preparation was divided into equal
aliquots, frozen on dry ice, and stored at ꢀ70ꢁC.
5.1.42.
2-Methyl-1-pentyl-3-(7-methoxy-1-naphthoyl)-
indole, JWH-159. JWH-159 was prepared from 7-meth-
oxy-1-naphthoic acid and 2-methyl-1-pentylindole by
method D. From 0.18g (0.9mmol) of acid and 0.24g
(1.2mmol) of 2-methyl-1-pentylindole there was ob-
tained after chromatography (petroleum ether/ethyl ace-
1
tate, 8:1) 0.19g (43%) of JWH-159 as a viscous oil: H
NMR (300MHz, CDCl3) d 0.91 (6.9, 3H), 1.18–1.26
(m, 4H), 1.80 (t, J = 7.3Hz, 2H), 2.50 (s, 3H), 3.79 (s,
3H), 4.12 (t, J = 7.5Hz, 2H), 7.01 (t, J = 7.8Hz, 1H),
7.15–7.24 (m, 3H), 7.32 (t, J = 7.8Hz, 2H), 7.55–7.59
(m, 2H), 7.80 (d, J = 8.9Hz, 1H), 7.89 (d, J = 7.9Hz,
1H); 13C NMR (75.5MHz, CDCl3) d 12.5, 13.9, 22.4,
29.1, 29.4, 43.4, 55.3, 103.7, 109.4, 115.0, 119.3, 121.2,
121.7, 122.1, 122.6, 127.2, 127.4, 129.5, 129.7, 130.1,
131.7, 136.0, 138.5, 145.0, 158.5, 193.8; MS (EI) m/z
385 (45), 328 (82), 207 (100); HRMS Calcd for
C26H27NO2: 385.2041, Found 385.2039.
5.3. Competition binding assays
5.3.1. CB1 assay. [3H]CP-55,940 binding to P2 mem-
branes was conducted as described elsewhere,50 except
whole brain (rather than cortex only) was used. CP-
55,940 and all cannabinoid analogs were prepared by
suspension in assay buffer from a 1mg/mL ethanolic
stock without evaporation of the ethanol (final concen-
tration of no more than 0.4%). Displacement curves
were generated by incubating drugs with 1nM of
[3H]CP-55,940. [3H]CP 55,940 bound to rat brain mem-
branes with a KD value of 0.68 0.07nM and a Bmax
value of 1.7 0.11pmol/mg. The assays were performed
5.2. Receptor binding experiments
5.2.1. Materials. Frozen whole brains of male Sprague–
Dawley rats were obtained from Harlan (Dublin, VA).

110
J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
in triplicate, and the results represent the combined
data from three individual experiments.
5.4.3. [35S]GTPcS binding assay. Prior to assays, sam-
ples were thawed on ice, centrifuged at 50,000g for
10min at 4ꢁC, and resuspended in Assay Buffer
(50mM Tris–HCl (pH7.4), 3mM MgCl2, 0.2mM
EGTA, and 100mM NaCl). Reactions containing 10
Bg of membrane protein were incubated for 1.5h at
30ꢁC in Assay Buffer containing 10 lM GDP, 0.1nM
[35S]GTPcS, 0.1% bovine serum albumin, and various
concentrations of agonist. Non-specific binding was
determined in the presence of 20 lM unlabeled GTPcS.
Reactions were terminated by rapid vacuum filtration
through GF/B glass fiber filters, and radioactivity was
measured by liquid scintillation spectrophotometry at
95% efficiency for 35S.
5.3.2. CB2 assay. Binding was assayed by a modification
of Compton et al.42 CP-55,940 and all cannabinoid ana-
logs were prepared by suspension in assay buffer from a
1mg/mL ethanolic stock without evaporation of the eth-
anol (final concentration of no more than 0.4%). The
incubation was initiated by the addition of 40–50lg
membrane protein to silanized tubes containing
[3H]CP-55,940 (102.9Ci/mmol) and a sufficient volume
of buffer C (50mM Tris–HCl, 1mM EDTA, 3mM
MgCl2, and 5mg/mL fatty acid free BSA, pH7.4) to
bring the total volume to 0.5mL. The addition of
1lM unlabelled CP-55,940 was used to assess non-spe-
cific binding. Following incubation (30ꢁC for 1h), bind-
ing was terminated by the addition of 2mL of ice cold
buffer D (50mM Tris–HCl, pH7.4, plus 1mg/mL
BSA) and rapid vacuum filtration through Whatman
GF/C filters (pretreated with polyethyleneimine (0.1%)
for at least 2h). Tubes were rinsed with 2mL of ice cold
buffer D, which was also filtered, and the filters subse-
quently rinsed twice with 4mL of ice cold buffer D. Be-
fore radioactivity was quantitated by liquid scintillation
spectrometry, filters were shaken for 1h in 5mL of scin-
tillation fluid. [3H]CP 55,940 bound to hCB2-CHO cells
membranes with a KD value of 0.45 0.07nM and a
Bmax value of 2.93 0.06pmol/mg.
5.4.4. Data analysis. Nonspecific [35S]GTPcS binding
was subtracted from all data. Basal [35S]GTPcS binding
is defined as specific [35S]GTPcS binding in the absence
of drug. Net-stimulated [35S]GTPcS binding is defined
as [35S]GTPcS binding in the presence of drug minus ba-
sal. Percent stimulation is expressed as (net stimulated
[35S]GTPcS binding/basal) · 100%. The net stimulation
produced by each concentration of every test compound
was normalized to that obtained by a maximally effec-
tive concentration of CP-55,940 (3lM), which was in-
cluded in one triplicate of each individual experiment
as an internal standard, according to the following
equation. Percent maximal CP-55,940 stimulation =
(net stimulated [35S]GTPcS binding by test com-
pound/net stimulated [35S]GTPcS binding by 3lM
CP-55,940) · 100%. In this way, individual concentra-
tion-effect curves of the percent maximal CP-55,940
stimulation produced by each test compound were
obtained and subjected to non-linear regression analysis.
All data are reported as mean Emax or EC50 values
SEM of 3–6 experiments, each performed in triplicate.
Nonlinear regression analysis was conducted by iterative
fitting of the concentration-effect curves using JMP
(SAS for Macintosh: Cary, NC). Statistically significant
differences among Emax values were determined by anal-
ysis of variance followed by post-hoc analysis with the
unpaired, two-tailed StudentÕs t-test using JMP.
5.3.3. Data analysis. Competition assays were conducted
with 1nM [3H]CP-55,940 and 6 concentrations (0.1nM
to 10lM displacing ligands). Displacement IC50 values
were originally determined by unweighted least-squares
linear regression of log concentration–percent displace-
ment data and then converted to Ki values using the
method of Cheng and Prusoff.51 All experiments were
performed in triplicate and repeated 3–6 times. All data
are reported as mean values SEM.
5.4. [35S]GTPcS binding experiments
5.4.1. Materials. All chemicals were from Sigma (St.
Louis, MO) except the following: [35S]GTPcS (1250Ci/
mmol) was purchased from New England Nuclear
Group (Boston, MA), GTPcS from Boehringer Mann-
heim (New York, NY), and DMEM/F-12 from Fischer
Scientific (Pittsburgh, PA). Whatman GF/B glass fiber
filters were purchased from Fisher Scientific (Pittsburgh,
PA).
5.5. Molecular modeling
5.5.1. Conformational analysis. The structures of the N-
propyl-C-2H series analogs: JWH-163 and JWH-180;
the N-propyl-C-2 methyl series analogs: JWH-151 and
JWH189; the N-pentyl-C-2H series analogs: JWH-166,
JWH-182, JWH-267; and the N-pentyl C-2-methyl series
analogs: JWH-153, JWH-181, and JWH-268 were built
in the Spartan molecular modeling program (V4.1.1;
Wavefunction, Inc. Irvine, CA). Each structure was min-
imized using the AM1, semi-empirical method. For each
minimized structure, AM1 conformational searches were
then performed for rotation about the carbonyl to indole
C-3 and carbonyl to naphthoyl C-1 bonds.
5.4.2. Membrane preparations. Chinese Hamster Ovary
(CHO) cells stably expressing the human CB2 receptor
(CB2–CHO) were cultured in a 50:50 mixture of DMEM
and Ham F-12 supplemented with 100U/mL penicillin,
100Bg/mL streptomycin, 0.25mg/mL G418, and 5%
fetal calf serum. Cells were harvested by replacement
of the media with cold phosphate-buffered saline conta-
ining 0.4% EDTA followed by agitation. Membranes
were prepared by homogenization of cells in 50mM
Tris–HCl, 3mM MgCl2, 1mM EGTA, pH7.4, centrifu-
gation at 50,000g for 10min at 4ꢁC, and resuspension in
the same buffer at 1.5mg/mL. Membranes were stored at
ꢀ80ꢁC until use.
5.5.2. Coordinate drive. In order to describe the energy
barrier for rotation about the carbonyl oxygen–carbonyl
carbon–naphthalene C-1-naphthalene C-2 torsion angle
in JWH-268 (33), an AM1 coordinate drive study was
undertaken using Spartan. The torsion angle was driven

J. W. Huffman et al. / Bioorg. Med. Chem. 13 (2005) 89–112
111
from its global minimum energy value of 99.47ꢁ to
ꢀ80.49ꢁ in 10ꢁ increments. The single point energies of
the lowest energy and highest energy conformers identi-
fied during this drive were calculated at the HF 3-21G*
level using Spartan.
residues in order to better simulate aromatic stacking
interactions.56
Each resultant receptor/ligand complex was analyzed for
the presence of hydrogen bonding and aromatic stack-
ing interactions. Aromatic stacking interactions were
identified using Burley and PetskoÕs criteria.56 These
investigators reported that aromatic–aromatic stacking
interactions in proteins operate at distances (d) of
5.5.3. CB1 receptor docking studies. Amino acid number-
ing system. In the discussion of receptor residues that
follows, the amino acid numbering scheme proposed
by Ballesteros and Weinstein52 is used. In this number-
ing system, the most highly conserved residue in each
transmembrane helix (TMH) of Class A GPCRs is as-
signed a locant of.50 This number is preceded by the
TMH number and may be followed in parentheses by
the sequence number. All other residues in a TMH are
numbered relative to this residue. In this numbering sys-
tem, for example, the most highly conserved residue in
TMH 2 of the CB1 receptor is D2.50(163). The residue
that immediately precedes it is A2.49 (162).
˚
4.5–7.0A between ring centroids. The angle (a) between
normal vectors of interacting aromatic rings typically is
between 30ꢁ and 90ꢁ, producing a Ôtilted-TÕ or Ôedge-to-
faceÕ arrangement of interacting rings. Residues and/or
ligand regions were designated here as participating in
an aromatic stacking interaction if they had centroid
˚
to centroid distances between 4.5 and 7.0A. These inter-
actions were further classified as Ôtilted-TÕ arrangements
if 30ꢁ 6 a 6 90ꢁ and as parallel arrangements for
a < 30ꢁ. In interactions where a = 0ꢁ, arrangements were
also identified as offset or not offset, as Hunter and co-
workers have shown that off-set parallel stacks are more
energetically favorable.57
5.5.4. Ligand/CB1 R* complex. Because agonists are
thought to have higher affinity for the activated form
of GPCRs,53 agonist ligands in the work reported here
were docked in a model of the activated state (R*) of
CB1. This R* CB1 model was created by modification
of our rhodopsin-based model of the inactive (R) form
of CB1 and guided by the biophysical literature on the
R to R* transition. A complete discussion of the crea-
tion of both our CB1 R and R* models can be found
in our published work.47,54
Acknowledgements
The work at Clemson was supported by grants
DA03590 and DA15340 to JWH, that at Virginia Com-
monwealth University by grant DA03672 to BRM and
DA05274 to DES, and that at Kennesaw State Univer-
sity by grants DA03934 and DA00489 to PHR, all from
the National Institute on Drug Abuse.
A recent CB1 mutation study has suggested that residues
F3.36, W5.43, and W6.48 are part of the binding site of
the aminoalkylindole, WIN55, 212-2.47 These results are
consistent with the earlier work of Shire, which showed
that the TMH4-E2-TMH5 region of CB1 contains resi-
dues critical for the binding of SR141716A and
WIN55,212-2.55 Because the indoles studied here are
structurally related to the aminoalkylindoles, we chose
to dock the indoles studied here in the same region of
CB1 (i.e., the TMH3-4-5-6 region). Each ligand was
docked in the CB1 TMH 3-4-5-6 region using interactive
computer graphics. For all analogs studied, the lowest
energy s-trans conformer of each ligand was used for
docking studies.46 The energy of the CB1 R* TMH bun-
dle/ligand complex was minimized using the AMBER*
united atom force field in Macromodel 6.5 (Schrodinger
Inc., Portland, OR). A distance dependent dielectric,
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