2-Hydroxyisoquinoline-1,3(2H,4H)-diones as inhibitors of HIV-1 integrase and reverse transcriptase RNase H domain: Influence of the alkylation of position 4

Article abstract of DOI:10.1016/j.ejmech.2010.11.033

We report herein the synthesis of a series of fifteen 2- hydroxyisoquinoline-1,3(2H,4H)-dione derivatives. Alkyl and arylalkyl groups were introduced on position 4 of the basis scaffold. All the compounds presented poor inhibitory properties against HIV-1 reverse transcriptase ribonuclease H (RNase H). Four compounds inhibited HIV-1 integrase at a low micromolar level. A docking study using the later crystallographic data available for PFV integrase allowed us to explain the slightly improved integrase inhibitory activities of 4-pentyl and 4-(3-phenylpropyl)-2-hydroxyisoquinoline-1,3(2H,4H)-diones, when compared to the basis scaffold. Physicochemical studies were consistent with 1:1 and 1:2 (metal/ligand) stoichiometries of the magnesium complexes in solution. Unfortunately all tested compounds exhibited high cellular cytotoxicity in cell culture which limited their applications as antiviral agents. However these identified integrase inhibitors provide a very good basis for the development of new hits.

Full text of DOI:10.1016/j.ejmech.2010.11.033

European Journal of Medicinal Chemistry 46 (2011) 535e546
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
2-Hydroxyisoquinoline-1,3(2H,4H)-diones as inhibitors of HIV-1 integrase and
reverse transcriptase RNase H domain: Influence of the alkylation of position 4
,
,
b
,
a,
Muriel Billamboz a b, Fabrice Bailly a , Cédric Lion b, Christina Calmels c,
*
Marie-Line Andréola c, Myriam Witvrouw d, Frauke Christ d, Zeger Debyser d,
Laura De Luca e, Alba Chimirri e, Philippe Cotelle a
,
b
a Université Lille Nord de France, F-59000 Lille, France
b USTL, EA 4478 Chimie moléculaire et formulation, F-59655 Villeneuve d’Ascq, France
c Institut Fédératif de Recherches “Pathologies Infectieuses et Cancers” (IFR 66), MCMP-UMR 5234 CNRS, Université Victor Segalen Bordeaux 2, F-33076 Bordeaux, France
d Molecular Medicine, K.U. Leuven and IRC KULAK, Kapucijnenvoer 33, B-3000 Leuven, Flanders, Belgium
e Dipartimento Farmaco-Chimico, Universita di Messina, Viale Annunziata, 98168 Messina, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
We report herein the synthesis of a series of fifteen 2-hydroxyisoquinoline-1,3(2H,4H)-dione derivatives.
Alkyl and arylalkyl groups were introduced on position 4 of the basis scaffold. All the compounds pre-
sented poor inhibitory properties against HIV-1 reverse transcriptase ribonuclease H (RNase H). Four
compounds inhibited HIV-1 integrase at a low micromolar level. A docking study using the later crys-
tallographic data available for PFV integrase allowed us to explain the slightly improved integrase
inhibitory activities of 4-pentyl and 4-(3-phenylpropyl)-2-hydroxyisoquinoline-1,3(2H,4H)-diones, when
compared to the basis scaffold. Physicochemical studies were consistent with 1:1 and 1:2 (metal/ligand)
stoichiometries of the magnesium complexes in solution. Unfortunately all tested compounds exhibited
high cellular cytotoxicity in cell culture which limited their applications as antiviral agents. However
these identified integrase inhibitors provide a very good basis for the development of new hits.
Ó 2010 Elsevier Masson SAS. All rights reserved.
Received 15 September 2010
Received in revised form
15 November 2010
Accepted 20 November 2010
Available online 27 November 2010
Keywords:
2-Hydroxyisoquinoline-1,3(2H,4H)-dione
Integrase
Ribonuclease H
Magnesium complexation
Antiretroviral
1. Introduction
agents remains essential and, in the last decade, two novel classes
of antiretroviral agents were developed. Viral entry inhibitors were
Human immunodeficiency virus type 1 (HIV-1) encodes three
enzymes that are required for viral replication: reverse transcrip-
tase, protease, and integrase (IN). Although drugs targeting reverse
transcriptase and protease are in wide use and have shown
effectiveness particularly when employed in combination, these
highly active antiretroviral therapies (HAART) still show important
limitations. These are costs, the patient’s ability to adhere to the
prescribed therapy, occurrence of various side effects due to drug
toxicity and most importantly, the loss of drug effectiveness over
time caused by development of resistance, including multidrug
resistance and cross-resistance [1]. The search for new anti-HIV-1
investigated, leading to Enfuvirtide, an injectable peptidic drug
blocking gp-41 mediated fusion which was licensed in 2003, and
to Maraviroc which was recently US FDA-approved. HIV-1 inte-
grase (IN) has also emerged as an attractive target because it is
necessary for stable infection and has no cellular human equiva-
lent. A plethora of HIV-1 integrase inhibitors were discovered in
the last decade but only one compound, Raltegravir, was US FDA-
approved in October 2007 [2,3]. This is the unique currently used
clinical drug targeting IN, which is administered as a new addition
to HAART regimens. Raltegravir has exhibited an excellent low
nanomolar and strand transfer selective in vitro IN inhibition (IC50
value of 2.7 nM), an IC95 value of 31 nM in the presence of normal
human serum (NHS), and synergistic effects in combination with
multiple current antiretroviral drugs. It is also active against
various viral strains that are resistant to other classes of anti-
retroviral agents. Only two other compounds are in clinical
development: GS-9137 (Elvitegravir) is in the late stages of clinical
development [4,5] whereas S/GSK 1349572 is in phases I and II
clinical trials [6,7]. Raltegravir’s clinical use has already evidenced
Abbreviations: HAART, highly active antiretroviral therapies; HIV-1, human
immunodeficiency virus type 1; IN, integrase; LDA, lithium diisopropylamide;
LEDGF, lens epithelium-derived growth factor; RT, reverse transcriptase; RNase H,
ribonuclease H.
* Corresponding author. Université Lille Nord de France, F-59000 Lille, France.
Tel.: þ33 320 33 72 31; fax: þ33 320 33 63 09.
E-mail address: fabrice.bailly@univ-lille1.fr (F. Bailly).
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.11.033

536
M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
Table 1
the development of viral resistances [4]. The predominant muta-
tions of the resistant viral strains were found in the vicinity of the
catalytic triad residues in the IN active site, and it is likely that they
affect its catalytic activities. This evidently shows that there is
a strong need to discover novel IN targeting hits with different
structural scaffolds.
Second generation IN inhibitors may be provided by compounds
with novel IN inhibition mechanisms like small-molecule inhibitors
of the LEDGF/p75-integrase interaction [8]. An alternative may be
given by multi-targeted compounds and, for example, we may take
advantage of the structural similarities between the catalytic cores
of HIV-1 reverse transcriptase RNase H domain [9e11] and HIV-1 IN
[12e18]. They share a similar ab-fold containing a central five-
Inhibition of HIV-1 IN and RT RNase H activities, antiviral activity and cytotoxicity of
4-substituted 2-hydroxyisoquinoline-1,3(2H,4H)-dione compounds.
R4
O
N
OH
O
d
e
Compd
R4
IC50
(
m
M)
IC50
(
mM)
RNase EC50
M)
CC50
M)
Overall INa RT RNase Hb H/INc
(
m
(m
5a
5b
5c
5d
CH3
C2H5
C3H7
CH(CH3)2
C4H9
C5H11
C6H13
C6H13
C7H15
CH2Ph
CH2Ph
CH2C6H4pCH3 3.4
CH2C6H4pCF3 23.2
(CH2)2Ph
3.3
38.8
70.0
46.8
18.5
13.2
33.6
38.0
7.8
11.8
4.5
2.2
0.52
0.3
24.9
3.3
0.2
0.4
e
>250
>250
>25.4
250
250
25.4
15.7
21.1
35.5
40.2
1.35
11.4
45.4
113.1
37.7
39.9
stranded mixed
b-sheet surrounded by a-helices on both sides,
which are in the same topological order. They also contain key acid
aminoacids (D64, D116 and E152 for HIV-1 IN; D443, E478, D498
and D549 for the RNase H domain) that are able to complex two
magnesium metal ions absolutely required for catalytic activity.
Compounds aimed at complexing magnesium cations in both
catalytic sites are likely to induce enzymatic functional impairment
and inhibit HIV-1 replication [9].
>122.5 122.5
5e0,5ei
5f
>25.4
>98.3
>4.4
25.4
98.3
4.4
5g
5g0
5h0
5i
>128.4 128.4
45
NTf
NTf
95
88
5.5
6.0
30
NAg
14.9
80
>95
>88
>5.5
>6.0
>30
>5.2
NTf
5i0
0.4
23.5
1.8
e
5j0,5ji
5k
We recently focused our attention on a new scaffold, 2-hydroxy-
isoquinoline-1,3(2H,4H)-dione as a potential lead compound for
the development of novel IN/RNase H inhibitors [19]. We ela-
borated a first series of derivatives variously substituted at position 7,
which were mostly selective for HIV-1 IN with an IC50 in the micro-
molar range. Surprisingly two new hits were discovered which
displayed high selectivity for IN (vs RNase H) with submicromolar
IC50 values. These enzymatic inhibitory properties may be related
to the metal-binding abilities of the compounds (1:1 stoichiometry).
Unfortunately all tested compounds exhibited high cellular cytot-
oxicity which limited their applications as antiviral agents. Never-
theless these first results encouraged us to further investigate the
pharmacomodulation of this scaffold. Our goal remains the discovery
of antiviral compounds with various antienzymatic profiles.
Herein we present the elaboration of a second series of
compounds substituted at position 4 by alkyl and arylalkyl chains.
These synthetic modulations of the original scaffold, aimed at
generating more amphiphilic molecules, were performed in order
to investigate the influence of the substitution pattern on the
enzymatic inhibitory and antiviral activities.
42.7
NAg
66.8
5.9
5l
27.8
2.6
6.3
5m0, 5mi (CH2)3Ph
25.7
0.9
5.2
5nh
H
NTf
a
Concentration required to inhibit by 50% the in vitro overall integrase activity.
Values are means þ/ꢀ standard deviations from at least three independent
experiments.
b
Concentration required to inhibit by 50% the in vitro RNase H activity.
IC50 RNase H/IC50 HIV-1 IN ratio.
Effective concentration required to reduce HIV-1-induced cytopathic effect by
c
d
50% in MT-4 cells.
e
Cytotoxic concentration to reduce MT-4 cell viability by 50%.
Non tested.
Non active.
Results reported from [19].
f
g
h
i
Tested as mixtures of both tautomers.
5aem as mixtures of keto and enol forms with a large preference
(>90% measured by 1H NMR) for the keto form. Washing the crude
solids with appropriate solvents allowed us to separate these two
forms in some cases. The keto and enol forms were generally
insoluble in dichloromethane and ethyl acetate, respectively. This
was the case for 5g/5g0 and 5i/5i0.
2. Chemistry
Novel 2-hydroxyisoquinoline-1,3(2H,4H)-dione derivatives
(Table 1) were prepared from methyl homophthalate 1a in 4 steps,
according to our previously reported method, as summarized in
Scheme 1 [19]. Substitution of the heterocyclic ring at position 4
was realized by alkylation of methyl homophthalate 1a by appro-
priate alkyl and arylalkyl halides after LDA-promoted deprotona-
tion of 1a in THF, giving compounds 2aek and 2m in 15e87% yields.
Under these standard conditions and whatever the number of base
equivalents, temperature and time of reaction which were applied,
we were unable to isolate 2l (where R4 ¼ (CH2)2Ph). We therefore
supposed that 1-bromo-2-phenylethane did not react under SN2
conditions which was probably due to the steric hindrance of the
benzyl group. In contrast, the use of sodium amide in liquid
ammonia led to 2l with a 65% yield. Under these SN1 conditions,
a cyclopropyl cation could be formed with the assistance of the
phenyl group and then react with the nucleophile. After saponifi-
cation of the precursors 2aem, homophthalic acids 3aem were
cyclized with O-benzylhydroxylamine in toluene at reflux in
a Dean-Stark apparatus to give the corresponding 2-benzylisoqui-
noline-1,3(2H,4H)-dione derivatives 4aem. Final deprotection
using boron tribromide (or trichloride) yielded the test compounds
3. Biological results
Table
1 shows enzymatic inhibitory properties for the
4-substituted derivatives (5aem) compared to the unsusbtituted
reference 5n. As encountered for 7-substituted compounds [19],
there was no improvement of RNase H inhibition amongst the
series. In most cases IC50 values ranged between 25
Only compound 5g0 (IC50 value of 7.8
M) was nearly as potent as
the reference unsubstituted compound 5n (IC50 value of 5.9 M)
mM and 50 mM.
m
m
whereas the other ones were 2e12-fold less inhibitory. RNase H
inhibition was even completely abolished for 5i and 5l.
As far as integrase inhibition is concerned, the best inhibitory
activity was obtained for an alkyl chain with an optimal length of
five carbons. Indeed, IC50 values progressively increased from
3.3
for 5f (pentyl group, 1.35
mM (5a, methyl group) to 113.1 m
M (5h0, heptyl group), except
m
M). The alkaryl sub-series gave similar
results: compounds bearing substituted benzyl (5i, 5i0,5k) and
phenethyl moieties (5l, 5l0) on position 4 displayed IC50 values
around 25.0e40.0
mM, whereas an optimal IC50 value of 2.6 mM was
obtained for 5m (3-phenylpropyl group).

M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
R4
537
R4
R4
O
O
CO2H
CO2H
CO2Me
CO2Me
CO2Me
iii
iv
i or i';
ii or ii'
N
CO2Me
OBn
3a-m
4a-m
1a
2a-m
v
R4
R4
OH
OH
O
N
N
OH
O
O
5a'-m'
5a-m
Scheme 1. Reagents and conditions: (i) 1.3 equiv LDA, ꢀ78 ꢃC, 1 h; (i0) 1.3 equiv NaNH2, ꢀ35 ꢃC, 10 min (ii) 1.0 equiv R4X, ꢀ78 ꢃC, 1 h then room temperature, 12 h; (ii0) 1.0 equiv
F
(CH2)2Br, ꢀ35 ꢃC, 4 h then room temperature; (iii) 2.5 M KOH, H2O/MeOH 2/1, reflux, 1 h; (iv) 1.2 equiv of NH2OBn, toluene, Dean-Stark apparatus, reflux, 12 h; (v) BBr3 or BCl3, 4.0
equiv, room temperature, 1 h; H2O, room temperature, 15 min.
The keto and enol forms of compounds bearing a hexyl group
(5g/5g0) and a benzyl group (5i/5i0) were separated and tested on
both enzymatic functions. Unfortunately with so few examples it is
impossible to draw any conclusion concerning the influence of the
tautomeric form on enzymatic inhibition.
transfer active site (Mg2þ or Mn2þ) [21]. This breakthrough now
allows for a better understanding of the binding mode of integrase
strand transfer inhibitors. In an “induced fit mechanism” theory,
lipophilic side chains of the inhibitor may fit into a hydrophobic
pocket created by displacement the adenine of conserved 30-CA end
dinucleotide of the viral DNA. As shown by Hare et al. [21,22], PFV
integrase can be considered as a good model for the development of
HIV-1 integrase strand transfer inhibitors. The secondary structures
of PFV IN (PDB: 3L2T) and HIV-1 IN catalytic core domain (PDB:
1BL3) have highly conserved architectures, with a calculated RMSD
Physicochemical studies for 7-substituted compounds using the
Job method were consistent with a single 1:1 stoichiometry of the-
magnesium complexes in solution and an enolization of the iso-
quinoline upon magnesium cation complexation [19]. For this novel
series,twometal/ligandstoichiometries(1:1and1:2)wereevidenced.
For example compound 5c has Ks values of 2.0 ꢁ 0.9 ꢂ 105 L molꢀ1 and
4.7 ꢁ 0.5 ꢂ107 L2 molꢀ2 for these two binding modes, respectively. It
seems that the 1:2 stoichiometry, indicating a somewhat lesser ability
to complex magnesium, correlates with lesser HIV-IN inhibition.
Finally, the antiviral properties were investigated by MT-4/MTT
assays [19]. All novel compounds displayed important cytotoxic-
ities, which hindered the detection of any antiviral activity in cell
culture (Table 1).
ꢀ
of 1.04 A (Fig. 1). Only the position of the known flexible loop
(G140eG149 in HIV-1 IN) strongly varies in these structures. It has
been suggested that its conformational flexibility is essential for
catalytic activity, this loop adopting a fixed conformation upon DNA
binding and stabilizing the 50- end of the viral DNA [24]. On the
basis of these considerations, we decided to undertake docking
studies of our molecules based on the 3L2T X-ray crystallographic
structure of PFV IN, according to a recently developed procedure
[25]. This procedure was validated by redocking raltegravir and
elvitegravir and superimposing the best obtained poses with their
4. Docking studies
Although RNase H inhibition was abolished in the case of this
4-substituted series, two compounds (namely 5f and 5m) displayed
a rather encouraging low micromolar inhibition of HIV-1 integrase,
with a slight 2.5e4.5-fold improvement of the IC50 value when
compared to the basis scaffold. In order to further understand the
structureeactivity relationship of this series and gain some insight
into the binding mode of our molecules, we decided to focus our
attention on integrase inhibition by carrying out molecular
modeling studies.
To date, no X-ray structure of the entire HIV-1 IN in interaction
with its cognate DNA with or without substrate has been solved.
There are many X-ray structures of truncated integrases. But full-
length integrase was used for the evaluation of the structural
determinants of the strand transfer and 30-processing reaction
specificities at the DNA-binding level [23]. There are fifteen avail-
able X-ray structures of the HIV-1 IN core domain which all include
one Mg2þ ion bound by two aspartate residues (D64 and D116) in
the active site [12e18]. However, there is increasing evidence in
support of a two-metal ion theory. For example, X-ray structures of
ASV integrase with Cd2þor Zn2þ showed a second binding site
between D64 and E152 [20] and most docking studies now consider
that IN may welcome a second Mg2þ ion in its active site. Recently,
Hare et al. solved the crystal structures of full-length prototype
foamy virus (PFV) integraseeDNA complexes with various HIV-1
integrase inhibitors, exhibiting two-metal ions in the strand
Fig. 1. Superimposition of integrase catalytic core domain X-Ray crystallographic
structures of PFV (PDB:3L2T, green) and HIV-1 (PDB:1BL3, orange) using Pymol [42].
Calculated RMSD ¼ 1.04 Å. (For interpretation of the references to colour in this figure
legend, the reader is referred to the web version of this article.)

538
M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
X-Ray counterparts in the 3L2T and 3L2U structures, respectively.
Using the GOLD docking suite [26], this method involves the use of
the CHEMPLP fitness function [27], which is well suited to IN
features as it allows for a good balance between steric comple-
mentarity, hydrogen bonding and metal binding.
In this docking model, introduction of a lipophilic alkyl side
chain of at least 3 carbons in position 4 of our scaffold enables: (a)
good overall burying of the ligand into the active site cavity, (b)
occupancy of the hydrophobic cavity created by displacement of
the 30-end adenosine and (c) strong chelation of the 2 Mg2þ cations.
Docking calculations carried out on our series of compounds reveal
a consensual mode of binding satisfying all these features (Fig. 2).
The modeled optimal length of the side chain is 5e7 carbons
(5feh), as longer chains do not allow the last two interaction
features to be satisfied simultaneously in this model. Indeed,
docking calculations of compounds bearing a longer C8, C9 or C10
alkyl chain (5oeq, see supplementary information) yield 2 main
poses: in the first one, the scaffold interacts correctly with both
magnesium cations, but the end of the lipophilic side chain is
skewed away from the hydrophobic pocket. In the second one, it is
the side chain which interacts ideally with its hydrophobic envi-
ronment, but the magnesium complexation is partially lost.
Experimental results indicate an optimal length of 5 carbons (5f,
IC50 ¼ 1.35
whereas a side chain of 7 carbons induces a loss of activity (5h0,
M). Docking of compounds bearing a shorter side chain
(R4 ¼ H, Me, Et) does not yield poses that fit the consensual binding
mode and it seems hazardous at this stage to study their interactions
with the target as they are small aromatic planar scaffolds that may
mM) which correlates well with modeling results (Fig. 3),
Fig. 3. Mode of binding of 5f.
IC50 ¼ 113.1
m
poses with a partial loss of magnesium binding. The phenylpropyl
side chain of 5m however perfectly allows such a position (Fig. 4),
yielding a best docking pose that fits our consensual mode of
interact with DNA or tyrosines via pep interactions.
Most interestingly, the modeling study of the arylalkyl series
leads to similar results. Introduction of an aromatic moiety on the
side chain reduces its positioning freedom, as the presence of the
binding with: (a) p-stacking with the viral DNA cytosine, (b) overall
hydrophobic interactions with the enzyme (Y212, P214, Q215, E221
of PFV IN which are all conserved in HIV-1 IN), (c) complexation of
the 2 Mg2þ cations. These results strongly correlate with biological
results on HIV-1 IN, since the activity of scaffold 5n is retained and
even slightly increased for 5m whereas it is partially lost for 5i/5i0
and 5l.
viral DNA cytosine can induce
p-stacking that partially replaces
classical hydrophobic interactions, as is the case for the p-fluo-
robenzyl group of raltegravir or elvitegravir [21]. However, in order
to retain ideal magnesium complexation and gain this aroma-
ticearomatic interaction, a flexible arm of three carbons is required.
Indeed the benzyl and phenethyl moieties (5i and 5l respectively)
do not provide sufficient distance between the aromatic ring and
the C4 carbon to allow both interactions, thus resulting in docking
Fig. 2. Superimposition of the best docking pose of ligands 5cem in the active site of
PFV IN using the GOLD docking suite and CHEMPLP fitness function. Conolly surfaces at
a 1.4 Å radius are depicted for the enzyme (blue) and the double-stranded viral DNA
(yellow). Magnesium cations are depicted in orange. (For interpretation of the refer-
ences to colour in this figure legend, the reader is referred to the web version of this
article.)
Fig. 4. Mode of binding of 5m.

M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
539
5. Conclusion
cooled to ꢀ78 ꢃC and 3.3 mL of 1.6 M n-butyllithium (5.3 mmol) in
THF was added. After 30 min reaction at ꢀ78 ꢃC, a solution of 1a
(1.00 g, 4.8 mmol) in 3.0 mL of dry THF was added dropwise. After
stirring the solution for 1 h at ꢀ78 ꢃC, a solution of alkyl or arylalkyl
halide (iodide in the case of 2a and bromide in the other cases)
(9.6 mmol) in a minimum of dry THF was added dropwise and the
solution was stirred for 1 h at ꢀ78 ꢃC and then for 12 h at room
temperature. The solution was quenched with 10 mL of saturated
aqueous NH4Cl solution and extracted several times with ether. The
organic layer was dried over Na2SO4 and concentrated invacuo. After
column chromatography of the residue (eluent: hexane/AcOEt, 90/
10), 2aek and 2m were obtained as colourless to yellowish oils.
Herein we investigated the HIV-1 IN and RT RNase H inhibitory
properties of a series of 4-alkylated 2-hydroxyisoquinoline-1,3
(2H,4H)-diones in order to gain further insight into the biological
profile of this previously studied scaffold. Introduction of various
linear alkyl chains or of alkaryl groups at position 4 led to the
identification of four moderate IN inhibitors at micromolar level (5a,
5f, 5j and 5m) with a slight 2e4.5-fold enhancement of the anti-
integrase activity, when compared to the unsubstituted parent
compound. These results were corroborated by docking studies
using the later crystallographic data available on PFV IN including its
complexes with Mg2þ or Mn2þ and raltegravir or elvitegravir. The
best antiintegrase activities were obtained for 5f and 5m, in accor-
dance with calculation results obtained from this docking model.
Among tested compounds, the pentyl groupof 5f may thus be able to
establish the best hydrophobic interactions inside the hydrophobic
cavity created by displacement of the 30-end adenosine, while the
phenylpropyl group of 5m is able to interact with both enzyme and
viral DNA by simultaneous hydrophobic contacts and aromatic
stacking. Nevertheless these interactions within the IN active site
together with chelation of the 2 Mg2þ cations are not strong enough
to allow for a strong enzyme inhibition by these compounds. It is
clear that alkylation of the position 4 of this scaffold is largely
insufficient for its current use for the development of a new class of
antiretroviral agents. However the promising results obtained for
this series indicate that optimization of this scaffold may lead to
a serious drug candidate. In this regard, further explorations are
currently underway in our laboratories concerning the pharmaco-
modulation of 5f and 5m, in order to discover new hits amongst this
family of compounds. These studies will be reported in due course
and will largely benefit from our validated docking method.
6.1.2.1. Methyl 2-(1-methoxy-1-oxopropan-2-yl)benzoate 2a. Colour-
less oil (87%). 1H NMR (300 MHz, CDCl3):
d
¼ 1.52 (d, 3H, CH3,
3J ¼ 7.0 Hz), 3.64 (s, 3H, OCH3), 3.88 (s, 3H, OCH3), 4.62 (q, 1H, CH,
3J ¼ 7.0 Hz), 7.25e7.51 (m, 3H, HAr), 7.90 (dd, 1H, H6, 3J ¼ 7.6 Hz,
4J ¼ 1.2 Hz); 13C NMR (75 MHz, CDCl3):
¼ 18.5 (CH3), 42.1 (CH), 52.0
d
(OCH3), 52.1 (OCH3), 126.9 (CH), 128.6 (CH), 129.4 (CIV), 130.8 (CH),
132.4 (CH), 142.1 (CIV), 167.9 (CO), 175.1 (CO); ESIeMS: m/z ¼ 223
(M þ H)þ.
6.1.2.2. Methyl 2-(1-methoxy-1-oxobutan-2-yl)benzoate 2b. Colour-
less oil (31%). 1H NMR (300 MHz, CDCl3):
d
¼ 0.80 (d, 3H, CH3,
3J ¼ 7.0 Hz), 1.70 (dq, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 7.3 Hz), 2.04 (dq, 1H,
CH2, 2J ¼ 13.5 Hz, 3J ¼ 6.3 Hz), 3.50 (s, 3H, OCH3), 3.76 (s, 3H, OCH3),
4.45 (tapp, 1H, CH, 3J ¼ 7.0 Hz), 7.13 (td, 1H, HAr
,
3J ¼ 6.9 Hz,
4J ¼ 1.0 Hz), 7.33 (m, 2H, HAr), 7.75 (dd, 1H, H6, 3J ¼ 6.9 Hz,
4J ¼ 1.0 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 12.0 (CH3), 26.5 (CH2),
48.3 (CH), 51.4 (OCH3), 51.7 (OCH3), 126.6 (CH), 128.4 (CH), 129.6
(CIV), 130.4 (CH), 131.9 (CH), 140.3 (CIV), 167.6 (CO), 174.1 (CO);
ESIeMS: m/z ¼ 237 (M þ H)þ.
6. Experimental
6.1.2.3. Methyl 2-(1-methoxy-1-oxopentan-2-yl)benzoate 2c. Colour-
less oil (30%). 1H NMR (300 MHz, CDCl3):
d
¼ 0.84 (t, 3H, CH3,
6.1. Chemistry
3J ¼ 7.3 Hz), 1.30 (m, 2H, CH2), 1.70 (qd, 1H, CH2, 2J ¼ 13.5 Hz,
3J ¼ 7.0 Hz), 2.07 (qd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 3.57 (s, 3H,
OCH3), 3.83 (s, 3H, OCH3), 4.58 (t, 1H, CH, 3J ¼ 7.0 Hz), 7.23 (td, 1H,
HAr, 3J ¼ 8.4 Hz, 4J ¼ 2.1 Hz), 7.40 (m, 2H, HAr), 7.80 (dd, 1H, H6,
Silica gel, 200e400 mesh (Merck) was used for column chro-
matography. Melting points were obtained on a Reichert Thermo-
pan melting points apparatus, equipped with a microscope. NMR
spectra were obtained on a AC 300 Bruker spectrometer in the
appropriate solvent with TMS as internal reference. J values are
given in Hz. Elemental analyses were performed by CNRS labora-
tories (Vernaison) and were within 0.4% of the theoretical values.
3J ¼ 8.4 Hz, 4J ¼ 2.1 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.8 (CH3),
20.8 (CH2), 35.7 (CH2), 46.7 (CH), 51.7 (OCH3), 52.0 (OCH3), 126.7
(CH), 127.8 (CH), 129.7 (CIV), 130.5 (CH), 132.0 (CH), 140.6 (CIV), 167.8
(CO), 174.4 (CO); ESIeMS: m/z ¼ 251 (M þ H)þ.
6.1.2.4. Methyl 2-(3-methyl-1-methoxy-1-oxobutan-2-yl)benzoate 2d.
6.1.1. Preparation of methyl homophthalate 1a
Yellow oil (22%). 1H NMR (300 MHz, CDCl3):
d
¼ 0.64 (d, 3H, CH3,
6.1.1.1. Methyl 2-(2-methoxy-2-oxoethyl)benzoate 1a. Homophthalic
acid (5.76 g, 32.0 mmol) was dissolved in MeOH (100 mL) and
thionyl chloride (5.1 mL, 70.4 mmol) was added dropwise at 0 ꢃC.
After stirring for 15 min at room temperature, the solution was
heated under reflux for 2 h and concentrated in vacuo. The residue
was dissolved in AcOEt and washed several times with 10% NaHCO3.
After drying over Na2SO4, the solvent was evaporated in vacuo to
yield 1a as a yellow oil, which crystallized on standing (95%). Crystals
were carefully washed with anhydrous ether and dried at room
temperature. Mp 48e49 ꢃC (39e56 ꢃC, [28,29]); 1H NMR (300 MHz,
3J ¼ 6.7 Hz), 1.05 (d, 3H, CH3, 3J ¼ 6.4 Hz), 2.30 (m, 1H), 3.57 (s, 3H,
OCH3), 3.85 (s, 3H, OCH3), 4.45 (d, 1H, CH, 3J ¼ 10.2 Hz), 7.23 (td, 1H,
3
4
3
HAr, J ¼ 7.8 Hz, J ¼ 1.6 Hz), 7.42 (td, 1H, HAr, J ¼ 7.8 Hz, 4J ¼ 1.6 Hz),
7.59 (dd, 1H, H3, 3J ¼ 7.8 Hz, 4J ¼ 1.6 Hz), 7.77 (dd, 1H, H6, 3J ¼ 7.8 Hz,
4J ¼ 1.6 Hz); 13C NMR (75 MHz, CDCl3):
¼ 19.8 (CH3), 21.5 (CH3), 32.5
d
(CH), 51.7 (OCH3), 52.1 (OCH3), 52.9 (CH),126.7 (CH),128.6 (CH),130.1
(CH), 130.9 (CIV), 131.9 (CH), 139.5 (CIV), 168.2 (CO), 174.5 (CO);
ESIeMS: m/z ¼ 251 (M þ H)þ.
6.1.2.5. Methyl 2-(1-methoxy-1-oxohexan-2-yl)benzoate 2e. Colour-
DMSO-d6):
d
¼ 3.60 (s, 3H, OCH3), 3.78 (s, 3H, OCH3), 4.00 (s, 2H,
less oil (15%). 1H NMR (300 MHz, CDCl3):
d
¼ 0.85 (t, 3H, CH3,
CH2), 7.36 (m, 3H, HAr), 7.92 (dd, 3J ¼ 8.2 Hz, 4J ¼ 2.0 Hz, 1H, HAr); 13
C
3J ¼ 7.0 Hz), 1.30 (m, 4H, (CH2)b,c), 1.73 (qd, 1H, (CH2)a, 2J ¼ 13.5 Hz,
3J ¼ 7.0 Hz), 2.05 (qd, 1H, (CH2)a, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 3.62 (s, 3H,
OCH3), 3.88 (s, 3H, OCH3), 4.59 (t, 1H, CH, 3J ¼ 7.0 Hz), 7.25 (td, 1H,
HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.4 Hz), 7.45 (m, 2H, HAr), 7.85 (dd, 1H, H6,
NMR (75 MHz, DMSO-d6):
127.4 (CH), 129.5 (C), 130.3 (CH), 132.4 (CH), 132.6 (CH), 135.9 (C),
166.9 (CO), 172.4 (CO).
d
¼ 36.7 (CH2), 51.4 (OCH3), 51.8 (OCH3),
3J ¼ 8.0 Hz, 4J ¼ 2.4 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 14.0 (CH3),
6.1.2. Preparation of the alkylated methyl homophthalates 2aem
22.6 (CH2), 30.0 (CH2), 33.4 (CH2), 47.0 (CH), 52.0 (OCH3), 52.2
(OCH3), 126.9 (CH), 128.7 (CH), 129.9 (CIV), 130.7 (CH), 132.2 (CH),
140.7 (CIV), 168.1 (CO), 174.7 (CO); ESIeMS: m/z ¼ 265 (M þ H)þ.
A
solution of freshly distilled diisopropylamine (0.75 mL,
5.3 mmol) in 3.0 mL of dry THF under an argon atmosphere was

540
M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
6.1.2.6. Methyl 2-(1-methoxy-1-oxoheptan-2-yl)benzoate 2f. Yellow
HAr, 3J ¼ 7.3 Hz), 7.53 (m, 3H, HAr), 7.77 (dd, 1H, H6, 3J ¼ 7.3 Hz,
oil (65%). 1H NMR (300 MHz, CDCl3):
d
¼ 0.71 (t, 3H, CH3,
4J ¼ 2.0 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 39.8 (CH2), 49.1 (CH), 52.0
3J ¼ 7.0 Hz), 1.14 (m, 6H, CH2), 1.65 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz,
3J ¼ 7.0 Hz), 1.96 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 3.45 (s,
3H, OCH3), 3.71 (s, 3H, OCH3), 4.52 (t, 1H, CH, 3J ¼ 7.0 Hz), 7.13 (td,
(OCH3), 52.2 (OCH3),124.2 (q, CF3, 1JC-F ¼ 285.0 Hz),125.4 (q, 2CH, C3 ,
0
3
2
0
0
C5 , JC-F ¼ 7.0 Hz), 125.8 (CH), 126.1 (CH), 127.1 (q, CIV, C4 , JC-
4
0
0
¼ 28.0 Hz), 128.0 (q, 2CH, C2 , C6 , JC-F ¼ 3.0 Hz), 129.4 (CIV), 130.8
F
1H, HAr
,
3J ¼ 8.0 Hz, 4J ¼ 2.4 Hz), 7.30 (m, 2H, HAr), 7.72 (dd, 1H, H6,
(CH), 132.3 (CH), 137.3 (CIV), 143.7 (CIV), 167.4 (CO), 173.8 (CO);
3J ¼ 8.0 Hz, 4J ¼ 2.4 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.6 (CH3),
ESIeMS: m/z ¼ 367 (M þ H)þ.
22.1 (CH2), 27.1 (CH2), 31.3 (CH2), 33.7 (CH2), 46.6 (CH), 51.3 (OCH3),
51.6 (OCH3), 126.4 (CH), 128.3 (CH), 129.5 (CIV), 130.3 (CH), 131.8
(CH), 140.5 (CIV), 167.4 (CO), 174.1 (CO); ESIeMS: m/z ¼ 279
(M þ H)þ.
6.1.2.12. Methyl 2-(1-methoxy-1-oxo-5-phenylpentan-2-yl)benzoate
2m. Yellow oil (27%). 1H NMR (300 MHz, CDCl3):
d
¼ 1.62e1.88 (m,
3H), 2.25 (qd, 1H, 2J ¼ 9.1 Hz, 3J ¼ 7.0 Hz), 2.61 (t, 2H, 3J ¼ 7.0 Hz),
3.56 (s, 3H, OCH3), 3.83 (s, 3H, OCH3), 4.72 (t, 1H, CH, 3J ¼ 7.0 Hz),
7.12e7.35 (m, 6H, HAr), 7.47 (d, 2H, HAr, 3J ¼ 7.5 Hz), 7.88 (dd, 1H,
6.1.2.7. Methyl 2-(1-methoxy-1-oxooctan-2-yl)benzoate 2g. Orange
oil (73%). 1H NMR (300 MHz, CDCl3):
d
¼ 0.71 (t, 3H, CH3,
H6, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 30.2
3J ¼ 7.0 Hz), 1.13 (m, 8H, CH2), 1.67 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz,
3J ¼ 7.0 Hz), 1.97 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 3.46 (s,
3H, OCH3), 3.72 (s, 3H, OCH3), 4.52 (t, 1H, CH, 3J ¼ 7.0 Hz), 7.11 (td,
(CH2), 33.9 (CH2), 36.1 (CH2), 47.3 (CH), 51.9 (OCH3), 52.3 (OCH3),
126.4 (CH), 127.6 (CH), 129.0 (2CH), 129.1 (2CH), 129.4 (CH), 130.9
(CIV), 131.2 (CH), 132.8 (CH), 141.3 (CIV), 142.9 (CIV), 168.3 (CO), 174.4
(CO); ESIeMS: m/z ¼ 327 (M þ H)þ.
1H, HAr
,
3J ¼ 8.0 Hz, 4J ¼ 2.4 Hz), 7.31 (m, 2H, HAr), 7.73 (dd, 1H, H6,
3J ¼ 8.0 Hz, 4J ¼ 2.4 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.7 (CH3),
22.3 (CH2), 27.4 (CH2), 28.8 (CH2), 31.3 (CH2), 33.4 (CH2), 46.6 (CH),
51.3 (OCH3), 51.6 (OCH3), 126.4 (CH), 128.3 (CH), 129.5 (CIV), 130.3
(CH), 131.8 (CH), 140.5 (CIV), 167.4 (CO), 174.0 (CO); ESIeMS: m/
z ¼ 293 (M þ H)þ.
6.1.2.13. Methyl 2-(1-methoxy-1-oxo-4-phenylbutan-2-yl)benzoate
2l [30]. A solution of 1a (1.00 g, 4.8 mmol) in dry ether (5.0 mL)
was added dropwise to a solution of sodium amide (1.6 eq,
6.3 mmol) in ammonia (25 mL) at ꢀ35 ꢃC [31]. Then a solution of
1-bromo-2-phenylethane (0.65 mL, 4.8 mmol) in dry ether
(5.0 mL) was added and the mixture was stirred at ꢀ35 ꢃC for four
hours. After complete evaporation of ammonia, water (15 mL)
was added to the mixture. After 10 min stirring at room temper-
ature, the solution was extracted twice with 10 mL of ether. The
organic layer was dried over Na2SO4 and concentrated in vacuo.
After column chromatography of the residue (eluent: hexane/
AcOEt, 80/20), 2l was obtained as a colourless oil (65%). 1H NMR
6.1.2.8. Methyl 2-(1-methoxy-1-oxononan-2-yl)benzoate 2h. Colour-
less oil (67%). 1H NMR (300 MHz, CDCl3):
d
¼ 0.77 (t, 3H, CH3,
3J ¼ 7.0 Hz), 1.16 (m, 10H, CH2), 1.60 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz,
3J ¼ 7.0 Hz), 2.00 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 3.52 (s,
3H, OCH3), 3.78 (s, 3H, OCH3), 4.56 (t,1H, CH, 3J ¼ 7.0 Hz), 7.16 (td, 1H,
HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.1 Hz), 7.36 (m, 2H, HAr), 7.78 (dd, 1H, H6,
3J ¼ 7.6 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.9 (CH3),
22.4 (CH2), 27.6 (CH2), 28.9 (CH2), 29.3 (CH2), 31.6 (CH2), 33.5 (CH2),
46.7 (CH), 51.5 (OCH3), 51.8 (OCH3), 126.5 (CH), 128.4 (CH), 129.6
(CIV), 130.4 (CH), 131.9 (CH), 140.6 (CIV), 167.6 (CO), 174.2 (CO);
ESIeMS: m/z ¼ 307 (M þ H)þ.
(300 MHz, CDCl3):
d
¼ 2.40e2.70 (m, 4H, (CH2)2), 3.64 (s, 3H,
OCH3), 3.82 (s, 3H, OCH3), 4.67 (t, 1H, CH, 3J ¼ 7.3 Hz), 7.14e7.34
(m, 6H, HAr), 7.47 (d, 2H, HAr
,
3J ¼ 7.6 Hz), 7.90 (d, 1H, H6,
3J ¼ 8.0 Hz); 13C NMR (75 MHz, CDCl3):
¼ 33.8 (CH2), 35.1 (CH2),
d
46.5 (CH), 51.8 (OCH3), 51.9 (OCH3), 125.8 (CH), 126.9 (CH), 128.2
(2CH), 128.6 (2CH), 129.8 (CIV), 130.6 (CH), 132.1 (CH), 134.2 (CH),
140.1 (CIV), 141.4 (CIV), 167.7 (CO), 174.1 (CO); ESIeMS: m/z ¼ 313
(M þ H)þ.
6.1.2.9. Methyl 2-(1-methoxy-1-oxo-3-phenylpropan-2-yl)benzoate 2i.
Colourless oil (57%). 1H NMR (300 MHz, CDCl3):
d
¼ 3.03 (dd, 1H, CH2,
2J ¼ 13.5 Hz, 3J ¼ 5.8 Hz), 3.41 (dd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 9.0 Hz),
3.60 (s, 3H, OCH3), 3.86 (s, 3H, OCH3), 4.99 ppm (dd, 1H, CH,
3J ¼ 5.8 Hz, 3J ¼ 9.0 Hz), 7.14e7.35 (m, 6H, HAr), 7.46 (m, 2H, HAr), 7.86
(dd, 1H, H6, 3J ¼ 7.6 Hz, 4J ¼ 1.2 Hz); 13C NMR (75 MHz, CDCl3):
6.1.3. Preparation of the homophthalic acid derivatives 3aem
6.1.3.1. 2-(1-Carboxyethyl)benzoic acid 3a. Compound 2a (0.74 g,
3.3 mmol) and KOH (1.85 g, 33.0 mmol) were dissolved in a solu-
tion of methanol (4.5 mL) and water (9.0 mL). After 1 h reflux, the
solution was acidified with 3.0 M HCl and extracted several times
with ether. The combined organic extracts were dried over Na2SO4
and concentrated in vacuo to afford 3a as an oil, which crystallized
on standing. White crystals were carefully washed with anhydrous
ether and dried at room temperature. (95%). Mp 140 ꢃC
d
¼ 40.0 (CH2), 49.1 (CH), 52.1 (OCH3), 52.2 (OCH3), 126.3 (CH), 127.1
(CH), 128.3 (2CH), 128.9 (CH), 129.3 (2CH), 129.8 (CIV), 130.8 (CH),
132.3 (CH), 139.3 (CIV), 140.1 (CIV), 167.9 (CO), 174.0 ppm (CO);
ESIeMS: m/z ¼ 299 (M þ H)þ.
6.1.2.10. Methyl 2-(1-methoxy-1-oxo-3-(4-methylphenyl)propan-2-yl)-
benzoate 2j. Yellow oil (74%). 1H NMR (300 MHz, acetone-d6):
d
¼ 2.23 (s, 3H, CH3), 3.01 (dd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 6.2 Hz), 3.40
(146e161 ꢃC, [32,33]); 1H NMR (300 MHz, acetone-d6):
d
¼ 1.45 (d,
(dd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 8.8 Hz), 3.50 (s, 3H, OCH3), 3.83 (s, 3H,
3H, CH3, 3J ¼ 7.0 Hz), 4.77 (q, 1H, CH, 3J ¼ 7.0 Hz), 7.30e7.57 (m, 3H,
OCH3), 5.05 (dd, 1H, CH, 3J ¼ 6.2 Hz, 3J ¼ 8.8 Hz), 7.02 (d, 2H, H3 e5
,
HAr), 7.94 (dd, 1H, H6, 3J ¼ 7.6 Hz, 4J ¼ 1.2 Hz); 13C NMR (75 MHz,
0
0
3J ¼ 8.2 Hz), 7.14 (d, 2H, H2 e6
3J ¼ 8.2 Hz), 7.30 (td, 1H, HAr,
acetone-d6):
d
¼ 18.8 (CH3), 42.0 (CH), 127.6 (CH), 129.2 (CH), 130.6
0
0
,
3J ¼ 7.3 Hz, 4J ¼ 2.6 Hz), 7.48 (m, 2H, HAr), 7.86 (dd, 1H, H6, 3J ¼ 7.3 Hz,
(CIV), 131.5 (CH), 133.1 (CH), 143.5 (CIV), 169.4 (CO), 175.8 (CO);
4J ¼ 2.6 Hz); 13C NMR (75 MHz, acetone-d6):
d
¼ 21.1 (CH3), 40.1 (CH2),
ESIeMS: m/z ¼ 195 (M þ H)þ.
49.7 (CH), 51.9 (OCH3), 52.4 (OCH3), 127.7 (CH), 129.3 (CH), 129.5
(2CH), 129.8 (2CH), 130.6 (CIV), 131.3 ppm (CH), 132.9 (CH), 136.2 (CIV),
137.1 (CIV), 140.9 (CIV), 168.2 (CO), 173.9 (CO); ESIeMS: m/z ¼ 313
(M þ H)þ.
6.1.3.2. 2-(1-Carboxypropyl)benzoic acid 3b. White crystals (97%).
Mp 138 ꢃC; 1H NMR (300 MHz, acetone-d6):
d
¼ 0.87 (t, 3H, CH3,
3J ¼ 7.3 Hz), 1.73 (m, 1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.3 Hz), 2.06 (m,
1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.3 Hz), 4.65 (t, 1H, CH, 3J ¼ 7.3 Hz),
7.34 (td, 1H, HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz), 7.52 (m, 2H, HAr), 7.94 (dd,
1H, H6, 3J ¼ 7.6 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, acetone-d6):
6.1.2.11. Methyl 2-(1-methoxy-1-oxo-3-(4-trifluoromethylphenyl)pro-
pan-2-yl)benzoate 2k. Colourless oil (97%). 1H NMR (300 MHz,
CDCl3):
d
¼ 3.03 (dd, 1H, CH2, 2J ¼ 9.1 Hz, 3J ¼ 5.1 Hz), 3.42 (dd, 1H,
d
¼ 12.6 (CH3), 27.3 (CH2), 48.8 (CH), 127.6 (CH), 129.2 (CH), 131.2
CH2, 2J ¼ 9.1 Hz, 3J ¼ 5.2 Hz), 3.54 (s, 3H, OCH3), 3.77 (s, 3H, OCH3),
4.90 (t, 1H, CH, 3J ¼ 5.1 Hz), 7.32 (d, 2H, HAr, 3J ¼ 7.3 Hz), 7.39 (d, 2H,
(CIV), 131.5 (CH), 133.0 (CH), 141.8 (CIV), 169.6 (CO), 175.2 (CO);
ESIeMS: m/z ¼ 209 (M þ H)þ.

M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
541
6.1.3.3. 2-(1-Carboxybutyl)benzoic acid 3c. Green oil (97%). 1H NMR
4J ¼ 1.6 Hz); 13C NMR (75 MHz, acetone-d6):
d
¼ 38.6 (CH2), 48.1
(300 MHz, CDCl3):
d
¼ 0.85 (t, 3H, CH3, 3J ¼ 7.3 Hz), 1.31 (m, 2H,
(CH), 125.5 (CH), 126.4 (CH), 127.5 (2CH), 128.0 (CH), 128.5 (2CH),
129.1 (CIV), 130.4 (CH), 131.8 (CH), 139.0 (CIV), 139.9 (CIV), 168.8 (CO),
173.7 ppm (CO); ESIeMS: m/z ¼ 271 (M þ H)þ.
CH2), 1.72 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 2.10 (qd, 1H,
CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 4.58 (t, 1H, CH, 3J ¼ 7.0 Hz), 7.25
(td, 1H, HAr, 3J ¼ 8.4 Hz, 4J ¼ 2.4 Hz), 7.41 (m, 2H, HAr), 7.79 (dd, 1H,
H6, 3J ¼ 8.4 Hz, 4J ¼ 2.1 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.9
6.1.3.10. 2-(1-Carboxy-2-(4-methylphenyl)ethyl)benzoic acid 3j.
White crystals (98%). Mp 165 ꢃC (175e176 ꢃC, [36]); 1H NMR
(CH3), 20.8 (CH2), 35.0 (CH2), 46.9 (CH), 127.2 (CH), 128.5 (CIV), 129.1
(CH), 131.8 (CH), 133.3 (CH), 140.9 (CIV), 173.4 (CO), 180.4 (CO);
ESIeMS: m/z ¼ 223 (M þ H)þ.
(300 MHz, acetone-d6):
d
¼ 2.19 (s, 3H, CH3), 2.99 (dd, 1H, CH2,
2J ¼ 13.5 Hz, 3J ¼ 5.6 Hz), 3.31 (dd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 9.1 Hz),
5.13 (dd, 1H, CH, 3J ¼ 5.6 Hz, 3J ¼ 9.1 Hz), 6.99 (d, 2H, HAr
,
6.1.3.4. 2-(1-Carboxy-2-methylpropyl)benzoic acid 3d. Yellow oil
3J ¼ 7.9 Hz), 7.15 (d, 2H, HAr, 3J ¼ 7.9 Hz), 7.31 (td, 1H, HAr, 3J ¼ 8.2 Hz,
4J ¼ 2.0 Hz), 7.48 (m, 2H, HAr), 7.96 (dd, 1H, H6, 3J ¼ 8.2 Hz,
(99%). 1H NMR (300 MHz, CDCl3):
d
¼ 0.71 (d, 3H, CH3, 3J ¼ 6.7 Hz),
1.14 (d, 3H, CH3, 3J ¼ 6.7 Hz), 2.30 (m, 1H, CH), 4.61 (d, 1H, CH,
4J ¼ 2.0 Hz); 13C NMR (75 MHz, acetone-d6):
d
¼ 21.0 (CH3), 39.8
3J ¼ 10.2 Hz), 7.34 (td, 1H, HAr
,
3J ¼ 7.8 Hz, 4J ¼ 1.8 Hz), 7.54 (td, 1H,
(CH2), 49.4 (CH), 127.8 (CH), 129.3 (CH), 129.5 (2CH), 129.8 (2CH),
130.7 (CIV), 131.7 (CH), 133.1 (CH), 136.1 (CIV), 137.5 (CIV), 141.6 (CIV),
168.4 (CO), 174.6 (CO); ESIeMS: m/z ¼ 285 (M þ H)þ.
HAr, 3J ¼ 7.8 Hz, 4J ¼ 1.8 Hz), 7.61 (dd, 1H, H3, 3J ¼ 7.8 Hz, 4J ¼ 1.8 Hz),
7.99 (dd, 1H, H6, 3J ¼ 7.8 Hz, 4J ¼ 1.8 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 19.9 (CH3), 21.7 (CH3), 31.9 (CH), 53.3 (CH), 127.3 (CH), 129.0
(CH), 129.8 (CIV), 131.5 (CH), 133.2 (CIV), 139.8 (CH), 173.4 (CO), 179.3
6.1.3.11. 2-(1-Carboxy-2-(4-trifluoromethylphenyl)ethyl)benzoic acid
3k. White crystals (97%). Mp 157 ꢃC; 1H NMR (300 MHz, DMSO-
(CO); ESIeMS: m/z ¼ 223 (M þ H)þ.
d6):
d
¼ 3.06 (dd, 1H, CH2, 2J ¼ 13.7 Hz, 3J ¼ 6.1 Hz), 3.39 (dd, 1H,
6.1.3.5. 2-(1-Carboxypentyl)benzoic acid 3e. White crystals (97%).
CH2, 2J ¼ 13.7 Hz, 3J ¼ 8.8 Hz), 4.99 (dd, 1H, CH, 3J ¼ 6.1 Hz,
3J ¼ 8.8 Hz), 7.30e7.60 (m, 6H, HAr), 7.69 (dd, 1H, H3, 3J ¼ 8.0 Hz,
Mp 124 ꢃC; 1H NMR (300 MHz, CDCl3):
d
¼ 0.84 (t, 3H, CH3,
3J ¼ 7.0 Hz), 1.28 (m, 4H, (CH2)b,c), 1.78 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz,
3J ¼ 7.0 Hz), 2.20 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 4.60 (t,
1H, CH, 3J ¼ 7.0 Hz), 7.29 (td, 1H, HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.1 Hz), 7.50 (m,
2H, HAr), 7.98 (dd, 1H, H6, 3J ¼ 8.0 Hz, 4J ¼ 2.1 Hz); 13C NMR (75 MHz,
4J ¼ 2.0 Hz), 7.82 (dd, 1H, H6, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz); 13C NMR
1
(75 MHz, DMSO-d6):
d
¼ 38.1 (CH2), 48.8 (CH), 124.7 (q, CF3, JC-
3
0
0
¼ 285.0 Hz), 125.2 (q, 2CH, C3 , C5 , JC-F ¼ 7.0 Hz), 125.9 (CH), 126.6
F
2
4
0
0
0
(CH), 127.0 (q, CIV, C4 , JC-F ¼ 28.0 Hz), 128.6 (q, 2CH, C2 , C6 , JC-
CDCl3):
d
¼ 13.9 (CH3), 22.6 (CH2), 25.6 (CH2), 29.9 (CH2), 47.3 (CH),
¼ 3.0 Hz),129.4 (CIV),130.8 (CH),132.3 (CH), 134.1 (CIV),143.9 (CIV),
F
127.2 (CH), 129.0 (CH), 129.3 (CIV), 131.5 (CH), 133.1 (CH), 140.8 (CIV),
171.5 (CO), 173.4 (CO); ESIeMS: m/z ¼ 339 (M þ H)þ.
172.5 (CO), 178.4 ppm (CO); ESIeMS: m/z ¼ 237 (M þ H)þ.
6.1.3.12. 2-(1-Carboxy-3-phenylpropyl)benzoic acid 3l. White crys-
tals (99%). Mp 143 ꢃC (141 ꢃC, [30]); 1H NMR (300 MHz, acetone-d6):
6.1.3.6. 2-(1-Carboxyhexyl)benzoic acid 3f. Yellow oil (99%). 1H
NMR (300 MHz, CDCl3):
d
¼ 0.84 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.24 (m,
d
¼ 2.35e2.86 (m, 4H, (CH2)2), 4.77 (t,1H, CH, 3J ¼ 7.3 Hz), 7.09e7.24
6H, CH2), 1.82 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 2.14 (qd,
1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 4.72 (t, 1H, CH, 3J ¼ 7.0 Hz),
7.31 (td, 1H, HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.1 Hz), 7.47 (m, 2H, HAr), 8.02 (dd,
(m, 5H, HAr), 7.36 (m, 1H, HAr), 7.54 (m, 2H, HAr), 7.97 (dd, 1H, H6,
3J ¼ 7.6 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, acetone-d6):
d
¼ 34.6
(CH2), 36.0 (CH2), 47.2 (CH),126.6 (CH),127.7 (CH),129.0 (2CH),129.1
(2CH),129.3 (CH),131.1 (CIV),131.6 (CH),133.1 (CH),141.6 (CIV),142.6
(CIV), 169.8 (CO), 175.3 (CO); ESIeMS: m/z ¼ 285 (M þ H)þ.
1H, H6, 3J ¼ 8.0 Hz, 4J ¼ 2.1 Hz); 13C NMR (75 MHz, CDCl3):
¼ 14.0
d
(CH3), 22.4 (CH2), 27.3 (CH2), 31.7 (CH2), 32.8 (CH2), 47.2 (CH), 127.2
(CH), 128.9 (CIV), 129.0 (CH), 131.6 (CIV), 133.1 (CH), 140.8 (CH), 172.7
(CO), 179.4 ppm (CO); ESIeMS: m/z ¼ 251 (M þ H)þ.
6.1.3.13. 2-(1-Carboxy-4-phenylbutyl)benzoic acid 3m. Yellow crys-
tals (98%). Mp 182 ꢃC (184 ꢃC, [37]); 1H NMR (300 MHz, CDCl3):
6.1.3.7. 2-(1-Carboxyheptyl)benzoic acid 3g. Yellow oil (95%). 1H
d
¼ 1.65e1.92 (m, 3H), 2.45 (qd, 1H, J ¼ 9.1 Hz, 3J ¼ 7.0 Hz), 2.66 (t,
2
NMR (300 MHz, CDCl3):
d
¼ 0.81 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.19 (m,
2H, CH2, 3J ¼ 7.0 Hz), 4.55 (t, 1H, CH, 3J ¼ 7.0 Hz), 7.10e7.38 (m, 6H,
8H, CH2), 1.80 (qd, 1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 2.14 (qd,
1H, CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 4.71 (t, 1H, CH, 3J ¼ 7.0 Hz),
7.28 (td, 1H, HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.4 Hz), 7.47 (m, 2H, HAr), 7.99 (dd,
HAr), 7.41 (d, 2H, HAr), 7.97 (dd, 1H, H6, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz); 13
C
NMR (75 MHz, CDCl3):
d
¼ 30.2 (CH2), 33.9 (CH2), 36.1 (CH2), 47.3
(CH), 126.6 (CH), 127.4 (CH), 128.2 (CIV), 129.3 (2CH), 129.8 (2CH),
130.1 (CH), 131.2 (CH), 132.2 (CH), 138.3 (CIV), 142.9 (CIV), 172.3 (CO),
174.5 (CO); ESIeMS: m/z ¼ 299 (M þ H)þ.
1H, H6, 3J ¼ 8.0 Hz, 4J ¼ 2.4 Hz); 13C NMR (75 MHz, CDCl3):
¼ 14.0
d
(CH3), 22.6 (CH2), 27.6 (CH2), 29.1 (CH2), 31.6 (CH2), 33.0 (CH2), 47.2
(CH), 127.1 (CH), 128.9 (CIV), 129.2 (CH), 131.5 (CIV), 132.9 (CH), 140.9
(CH), 172.3 (CO), 179.0 (CO); ESIeMS: m/z ¼ 265 (M þ H)þ.
6.1.4. Preparation of the 2-benzyloxyisoquinoline-1,3-diones
4aem [19]
6.1.4.1. 2-Benzyloxy-4-methylisoquinoline-1,3(2H,4H)-dione 4a. After
column chromatography of the residue (eluent: hexane/AcOEt,
80/20), 4a was obtained as a yellow oil (88%). 1H NMR (300 MHz,
6.1.3.8. 2-(1-Carboxyoctyl)benzoic acid 3h. Yellow oil (99%). 1H
NMR (300 MHz, CDCl3):
d
¼ 0.85 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.24 (m,
10H, 5CH2), 1.85 (qd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 2.15 (qd, 1H,
CH2, 2J ¼ 13.5 Hz, 3J ¼ 7.0 Hz), 4.74 (t, 1H, CH, 3J ¼ 7.0 Hz), 7.32 (td,
1H, HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.1 Hz), 7.51 (m, 2H, HAr), 8.04 (dd, 1H, H6,
CDCl3):
d
¼ 1.52 (d, 3H, CH3, 3J ¼ 7,0 Hz), 4.62 (q, 1H, CH, 3J ¼ 7.0 Hz),
5.06 (s, 2H, OCH2), 7.25e7.51 (m, 8H, HAr), 7.90 (dd, 1H, H8,
3J ¼ 8.0 Hz, 4J ¼ 2.1 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 14.1 (CH3),
3J ¼ 7.6 Hz, 4J ¼ 1.2 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 18.5 (CH3),
22.6 (CH2), 27.7 (CH2), 29.1 (CH2), 29.5 (CH2), 31.8 (CH2), 32.9 (CH2),
47.2 (CH), 127.2 (CH), 128.8 (CH), 129.1 (CIV), 131.8 (CH), 133.2 (CIV),
141.0 (CH), 173.0 (CO), 179.8 (CO); ESIeMS: m/z ¼ 279 (M þ H)þ.
42.1 (CH, C4), 77.6 (OCH2), 126.9 (CH), 128.5 (2CH), 128.6 (CH), 128.8
(CH),129.2 (2CH),129.4 (CIV), 130.8 (CH), 132.4 (CH), 133.8 (CIV),142.1
(CIV), 167.9 (CO), 175.1 (CO); ESIeMS: m/z ¼ 282 (M þ H)þ.
6.1.3.9. 2-(1-Carboxy-2-phenylethyl)benzoic acid 3i. White crystals
(97%). Mp 165 ꢃC (154e167 ꢃC, [34,35]); 1H NMR (300 MHz,
6.1.4.2. 2-Benzyloxy-4-ethylisoquinoline-1,3(2H,4H)-dione 4b. After
column chromatography of the residue (eluent: hexane/AcOEt,
80/20), 4b was obtained as a colourless oil (79%). Keto form: 100%.
acetone-d6):
d
¼ 3.02 (dd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 5.8 Hz), 3.35
(dd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 9.1 Hz), 5.12 (dd, 1H, CH, 3J ¼ 5.8 Hz,
3J ¼ 9.1 Hz), 7.10e7.59 (m, 8H, HAr), 7.95 (dd, 1H, H6, 3J ¼ 7.2 Hz,
1H NMR (300 MHz, CDCl3):
d
¼ 0.65 (t, 3H, CH3, 3J ¼ 7.3 Hz), 1.88 (m,
1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 7.3 Hz, 3J ¼ 5.1 Hz), 2.17 (m, 1H, CH2,

542
M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
2J ¼ 13.5 Hz, 3J ¼ 7.3 Hz, 3J ¼ 5.1 Hz), 3.90 (t,1H, CH, 3J ¼ 5.1 Hz), 5.09
(s, 2H, OCH2), 7.16e7.39 (m, 6H, HAr), 7.52 (m, 2H, HAr), 8.17 (dd, 1H,
(m, 8H, CH2), 1.84 (qd, 1H, CHeCH2eCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.4 Hz),
2.07 (qd,1H, CHeCH2eCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.4 Hz), 3.94 (t,1H, CH,
3J ¼ 5.4 Hz), 5.14 (s, 2H, OCH2), 7.10e7.40 (m, 5H, HAr), 7.45e7.68 (m,
3H, HAr), 8.18 (dd, 1H, H8, 3J ¼ 7.8 Hz, 4J ¼ 1.9 Hz); 13C NMR (75 MHz,
H8, 3J ¼ 7.6 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, CDCl3):
¼ 9.1 (CH3),
d
29.7 (CH2), 48.1 (CH, C4), 78.0 (OCH2), 125.1 (CIV), 126.8 (CH), 127.5
(CH), 127.8 (CIV), 128.1 (2CH), 128.3 (CH), 128.8 (CH), 129.6 (2CH),
133.8 (CH), 137.9 (CIV), 161.2 (CO), 169.2 (CO); ESIeMS: m/z ¼ 296
(M þ H)þ
CDCl3):
d
¼ 13.7 (CH3), 22.2 (CH2), 24.7 (CH2), 28.7 (CH2), 31.1 (CH2),
36.5 (CH2), 47.3 (CH, C4), 77.8 (OCH2), 125.0 (CIV), 126.8 (CH), 127.3
(CH), 128.1 (2CH), 128.4 (CH), 128.7 (CH), 129.6 (2CH), 133.6 (CH),
133.9 (CIV), 138.4 (CIV), 161.1 (CO), 169.2 (CO); ESIeMS: m/z ¼ 352
(M þ H)þ.
6.1.4.3. 2-Benzyloxy-4-propylisoquinoline-1,3(2H,4H)-dione 4c. After
column chromatography of the residue (eluent: hexane/AcOEt,
70/30), 4c was obtained as a yellow oil (51%). Keto form: 100%. 1H
6.1.4.8. 2-Benzyloxy-4-heptylisoquinoline-1,3(2H,4H)-dione 4h. After
column chromatography of the residue (eluent: hexane/AcOEt,
80/20), 4h was obtained as a yellow oil (88%). Keto form: 100%. 1H
NMR (300 MHz, CDCl3):
d
¼ 0.79 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.06e1.25
(m, 2H, CH2eCH2eCH3), 1.86 (qd, 1H, CHeCH2eCH2, 2J ¼ 13.5 Hz,
3J ¼ 5.3 Hz), 2.03 (qd, 1H, CHeCH2eCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.3 Hz),
3.95 (t,1H, CH, 3J ¼ 5.3 Hz), 5.12 (s, 2H, OCH2), 7.21e7.44 (m, 6H, HAr),
7.52 (m, 2H, HAr), 8.17 (dd, 1H, H8, 3J ¼ 7.3 Hz, 4J ¼ 2.0 Hz); 13C NMR
NMR (300 MHz, CDCl3):
d
¼ 0.95 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.20e1.40
(m, 10H, CH2), 1.98 (m, 2H, CH2), 3.96 (t, 1H, CH, 3J ¼ 6.0 Hz), 5.15 (s,
2H, OCH2), 7.16e7.47 (m, 7H, HAr), 7.65 (td, 1H, HAr, 3J ¼ 7.5 Hz,
4J ¼ 1.9 Hz), 8.17 (dd, 1H, H8, 3J ¼ 7.5 Hz, 4J ¼ 1.9 Hz); 13C NMR
(75 MHz, CDCl3):
d
¼ 13.7 (CH3), 18.4 (CH2), 39.0 (CH2), 47.6 (CH, C4),
78.2 (OCH2), 125.2 (CIV), 127.0 (CH), 127.6 (CH), 128.3 (2CH), 128.7
(CH),129.0 (CH),129.9 (2CH), 133.9 (CH),134.0 (CIV),138.5 (CIV),161.4
(CO), 169.5 (CO); ESIeMS: m/z ¼ 310 (M þ H)þ.
(75 MHz, CDCl3):
d
¼ 13.7 (CH3), 21.2 (CH2), 22.2 (CH2), 25.6 (CH2),
28.6 (CH2), 31.3 (CH2), 36.4 (CH2), 44.9 (CH), 77.8 (OCH2), 124.9 (CIV),
126.7 (CH), 127.1 (CH), 127.4 (2CH), 127.9 (2CH), 128.6 (CH), 130.0
(CH), 134.9 (CH), 134.9 (CIV), 138.2 (CIV), 160.6 (CO), 167.5 (CO);
ESIeMS: m/z ¼ 366 (M þ H)þ.
6.1.4.4. 2-Benzyloxy-4-isopropylisoquinoline-1,3(2H,4H)-dione 4d.
After column chromatography of the residue (eluent: hexane/
AcOEt, 70/30), 4d was obtained as a yellow oil (51%). Keto form:
6.1.4.9. 4-Benzyl-2-benzyloxy-isoquinoline-1,3(2H,4H)-dione 4i. After
column chromatography of the residue (eluent: hexane/AcOEt,
80/20), 4i was obtained as a colourless oil (81%). Keto form: 100%. 1H
100%. 1H NMR (300 MHz, CDCl3):
d
¼ 0.82 (t, 3H, CH3, 3J ¼ 7.0 Hz),
0.99 (d, 3H, CH3, 3J ¼ 7.0 Hz), 2.30 (dsept, 1H, CH, 3J ¼ 7.0 Hz,
3J ¼ 4.0 Hz), 3.85 (d, 1H, CH, 3J ¼ 4.0 Hz), 5.12 (s, 2H, OCH2),
7.22e7.48 (m, 5H, HAr), 7.58 (m, 3H, HAr), 8.19 (dd, 1H, H8,
NMR (300 MHz, acetone-d6):
d
¼ 3.37 (dd, 1H, CH2, 2J ¼ 13.0 Hz,
3J ¼ 5.0 Hz), 3.57 (dd, 1H, CH2, 2J ¼ 13.0 Hz, 3J ¼ 5.6 Hz), 4.44 (t, 1H,
CH, 3J ¼ 5.3 Hz), 4.86 (d, 1H, OCH2, 2J ¼ 9.1 Hz), 4.99 (d, 1H, OCH2,
2J ¼ 9.1 Hz), 7.06e7.63 (m, 11H, HAr), 8.02 (m, 3H, HAr); 13C NMR
3J ¼ 7.8 Hz, 4J ¼ 1.8 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 17.9 (CH3),
19.0 (CH3), 36.7 (CH), 53.6 (CH), 77.8 (OCH2), 125.3 (CIV), 127.2 (CH),
127.3 (CH), 127.8 (2CH), 128.0 (CH), 128.5 (CH), 129.3 (2CH), 132.9
(CH), 133.5 (CIV), 136.9 (CIV), 161.1 (CO), 168.2 (CO); ESIeMS: m/
z ¼ 310 (M þ H)þ.
(75 MHz, acetone-d6):
d
¼ 42.9 (CH2), 49.1 (CH, C4), 78.3 (OCH2),
125.8 (CH), 126.4 (CH), 128.0 (CH), 128.2 (CH), 128.5 (2CH), 128.7
(2CH), 128.8 (CH), 129.2 (2CH), 129.3 (2CH), 130.4 (CH), 131.8 (CIV),
133.8 (CIV),139.0 (CIV), 139.8 (CIV), 161.2 (CO), 169.0 (CO); ESIeMS: m/
z ¼ 358 (M þ H)þ.
6.1.4.5. 2-Benzyloxy-4-butylisoquinoline-1,3(2H,4H)-dione 4e. After
column chromatography of the residue (eluent: hexane/AcOEt,
80/20), 4e was obtained as a yellow oil (98%). Keto form: 100%. 1H
6.1.4.10. 2-Benzyloxy-4-(4-methylbenzyl)isoquinoline-1,3(2H,4H)-
dione 4j. After column chromatography of the residue (eluent:
hexane/AcOEt, 80/20), 4j was obtained as a yellow oil (98%). Keto
NMR (300 MHz, CDCl3):
d
¼ 0.78 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.05e1.26
(m, 4H, (CH2)b,c), 1.86 (qd, 1H, CHeCH2eCH2, 2J ¼ 13.5 Hz,
3J ¼ 5.3 Hz), 2.07 (qd, 1H, CHeCH2eCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.3 Hz),
3.95 (t,1H, CH, 3J ¼ 5.3 Hz), 5.11 (s, 2H, OCH2), 7.15e7.43 (m, 6H, HAr),
7.60 (m, 2H, HAr), 8.18 (dd, 1H, H8, 3J ¼ 7.3 Hz, 4J ¼ 2.0 Hz); 13C NMR
form: 100%. 1H NMR (300 MHz, CDCl3):
d
¼ 2.22 (s, 3H, CH3), 3.28
(dd, 1H, CH2, 2J ¼ 13.0 Hz, 3J ¼ 4.4 Hz), 3.45 (dd, 1H, CH2,
2J ¼ 13.0 Hz, 3J ¼ 5.8 Hz), 4.26 (t, 1H, CH, 3J ¼ 4.8 Hz), 4.89 (d, 1H,
(75 MHz, CDCl3):
d
¼ 13.5 (CH3), 22.1 (CH2), 26.8 (CH2), 36.3 (CH2),
OCH2, 2J ¼ 8.9 Hz), 5.02 (d, 1H, OCH2, 2J ¼ 8.9 Hz), 6.66 (d, 2H, HAr
,
47.4 (CH, C4), 77.9 (OCH2), 124.9 (CIV), 126.8 (CH), 127.4 (CH), 128.0
(2CH), 128.4 (CH), 128.8 (CH), 129.7 (2CH), 133.8 (CH), 133.9 (CIV),
138.4 (CIV), 161.2 (CO), 169.3 (CO); ESIeMS: m/z ¼ 324 (M þ H)þ.
3J ¼ 7.6 Hz), 6.92 (d, 2H, HAr, 3J ¼ 7.6 Hz), 7.20 (m, 2H, HAr), 7.40 (m,
3H, HAr), 7.59 (m, 3H, HAr), 8.12 (dd,1H, H8, 3J ¼ 7.6 Hz, 4J ¼ 2.0 Hz);
13C NMR (75 MHz, CDCl3):
d
¼ 20.7 (CH3), 42.3 (CH2), 48.7 (CH),
77.9 (OCH2), 125.0 (CIV), 127.3 (CH), 127.5 (CH), 127.9 (CH), 128.1
(2CH), 128.6 (2CH), 128.7 (CH), 129.0 (2CH), 129.5 (2CH), 131.8
(CIV), 133.3 (CIV), 134.0 (CIV), 136.5 (CH), 137.3 (CIV), 160.6 (CO),
168.5 (CO); ESIeMS: m/z ¼ 372 (M þ H)þ.
6.1.4.6. 2-Benzyloxy-4-pentylisoquinoline-1,3(2H,4H)-dione 4f. After
column chromatography of the residue (eluent: hexane/AcOEt,
80/20), 4f was obtained as a yellow oil (97%). Keto form: 100%. 1H
NMR (300 MHz, CDCl3):
d
¼ 0.76 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.00e1.27
(m, 6H, (CH2)b,c,d), 1.82 (qd, 1H, CHeCH2eCH2, 2J ¼ 13.5 Hz,
3J ¼ 5.3 Hz), 2.03 (qd, 1H, CHeCH2eCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.3 Hz),
3.92 (t, 1H, CH, 3J ¼ 5.3 Hz), 5.11 (s, 2H, OCH2), 7.10e7.37 (m, 5H,
HAr), 7.47e7.60 (m, 3H, HAr), 8.15 (dd, 1H, H8, 3J ¼ 8.0 Hz,
6.1.4.11. 2-Benzyloxy-4-(4-trifluoromethyl)phenylisoquinoline-1,3(2H,-
4H)-dione 4k. After column chromatography of the residue (eluent:
hexane/AcOEt, 80/20), 4k was obtained as a yellow oil (80%). Keto
form: 100%. 1H NMR (300 MHz, acetone-d6):
d
¼ 3.48 (dd, 1H, CH2,
4J ¼ 2.0 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.6 (CH3), 22.1 (CH2),
2J ¼ 13.5 Hz, 3J ¼ 5.0 Hz), 3.62 (dd, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 5.6 Hz),
4.54 (t,1H, CH, 3J ¼ 5.3 Hz), 4.88 (d,1H, OCH2, 2J ¼ 9.1 Hz), 4.99 (d,1H,
OCH2, 2J ¼ 9.1 Hz), 7.04 (d, 2H, HAr, 3J ¼ 7.9 Hz), 7.30e7.70 (m, 10H,
HAr), 8.02 (dd, 1H, H8, 3J ¼ 7.7 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz,
24.4 (CH2), 31.1 (CH2), 36.4 (CH2), 47.3 (CH, C4), 77.8 (OCH2), 124.9
(CIV), 126.8 (CH), 127.3 (CH), 128.0 (2CH), 128.4 (CH), 128.7 (CH),
129.6 (2CH), 133.6 (CH), 133.8 (CIV), 138.3 (CIV), 161.1 (CO), 169.3
(CO); ESIeMS: m/z ¼ 338 (M þ H)þ.
acetone-d6):
d
¼ 42.4 (CH2), 49.1 (CH), 78.5 (OCH2), 125.7 (q, 2CH, 3JC-
¼ 7.6 Hz), 127.48 (CIV), 127.54 (CH), 128.5 (q, CF3, 1JC-F ¼ 270.0 Hz),
F
6.1.4.7. 2-Benzyloxy-4-hexylisoquinoline-1,3(2H,4H)-dione 4g. After
column chromatography of the residue (eluent: hexane/AcOEt,
80/20), 4g was obtained as a yellow oil (90%). Keto form: 100%. 1H
128.66 (2CH), 128.74 (CH), 128.8 (q, 2CH, 4JC-F ¼ 3.8 Hz), 129.1 (2CH),
129.3 (q, CIV, 2JC-F ¼ 35.0 Hz), 130.3 (CH), 133.3 (CH), 134.7 (CH), 135.6
5
(CIV), 138.4 (CIV), 141.7 (q, CIV, JC-F ¼ 1.1 Hz), 161.4 (CO), 169.1 (CO);
NMR (300 MHz, CDCl3):
d
¼ 0.84 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.01e1.35
ESIeMS: m/z ¼ 426 (M þ H)þ.

M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
543
6.1.4.12. 2-Benzyloxy-4-(2-phenyl)ethylisoquinoline-1,3(2H,4H)-di-
one 4l. After column chromatography of the residue (eluent:
hexane/AcOEt, 80/20), 4l was obtained as a yellow oil (48%). Keto
6.1.5.3. 2-Hydroxy-4-propylisoquinoline-1,3(2H,4H)-dione 5c. Brown
oil (75%). Keto form (5c): 90%.1H NMR (300 MHz, CDCl3):
d
¼ 0.75 (t,
3H, CH3, 3J ¼ 7.3 Hz), 1.04 (m, 2H, CHeCH2eCH3), 1.92 (qd, 1H,
CHeCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.4 Hz), 2.11 (qd,1H, CHeCH2, 2J ¼ 13.5 Hz,
3J ¼ 5.4 Hz), 4.04 (t, 1H, CH, 3J ¼ 5.4 Hz), 7.25e7.40 (m, 2H, HAr), 7.58
(td, 1H, HAr, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz), 8.09 (dd, 1H, H8, 3J ¼ 7.6 Hz,
form: 100%. 1H NMR (300 MHz, CDCl3):
d
¼ 3.32e3.35 (m, 4H,
(CH2)2), 4.39 (t, 1H, CH, 3J ¼ 5.0 Hz), 5.07 (s, 2H, OCH2), 6.78 (m, 4H,
HAr), 7.16e7.68 (m, 9H, HAr), 8.08 (dd, 1H, H8, 3J ¼ 7.6 Hz,
4J ¼ 2.0 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 31.1 (CH2), 37.8 (CH2),
4J ¼ 1.6 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.7 (CH3), 18.1 (CH2),
46.7 (CH), 77.9 (OCH2), 125.1 (CIV), 125.9 (CH), 126.8 (CH), 127.6
(CH), 128.16 (2CH), 128.22 (2CH), 128.24 (2CH), 128.6 (CH), 128.8
(CH), 129.7 (2CH), 133.8 (CH), 133.9 (CIV), 138.1 (CIV), 140.1 (CIV),
161.0 (CO), 168.9 (CO); ESIeMS: m/z ¼ 372 (M þ H)þ.
38.4 (CH2), 48.6 (CH, C4), 124.3 (CIV), 127.0 (CH), 127.7 (CH), 128.6
(CH), 134.1 (CH), 138.4 (CIV), 160.9 (CO), 169.1 (CO); ESIeMS:
m/z ¼ 220 (M þ H)þ; Anal. Calc. For C12H13NO3: C, 65.74, H, 5.98, N,
6.39; Found: C, 65.66, H, 6.08, N, 6.57.
6.1.4.13. 2-Benzyloxy-4-(3-phenyl)propylisoquinoline-1,3(2H,4H)-di-
one 4m. After column chromatography of the residue (eluent:
hexane/AcOEt, 80/20), 4m was obtained as a yellow oil (98%). Keto
6.1.5.4. 2-Hydroxy-4-isopropylisoquinoline-1,3(2H,4H)-dione 5d.
Beige solid (47%). Keto form (5d): 100%. Mp 109e111 ꢃC; 1H NMR
(300 MHz, DMSO-d6):
d
¼ 0.76 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.00 (d, 3H,
form: 100%.1H NMR (300 MHz, CDCl3):
d
¼ 1.54e1.98 (m, 4H, 2CH2),
CH3, 3J ¼ 7.0 Hz), 2.34 (dsept, 1H, CH, 3J ¼ 7.8 Hz, 3J ¼ 7.0 Hz), 3.97
(d, 1H, 3J ¼ 7.8 Hz), 7.47 (m, 2H, HAr), 7.66 (td, 1H, HAr, 3J ¼ 7.7 Hz,
4J ¼ 1.6 Hz), 8.06 (dd, 1H, H8, 3J ¼ 7.7 Hz, 4J ¼ 1.6 Hz); 13C NMR
2.65 (m, 2H, CH2), 4.32 (t, 1H, CH, 3J ¼ 5.1 Hz), 4.98 (d, 1H, OCH2,
2J ¼ 9.1 Hz), 5.04 (d, 1H, OCH2, 2J ¼ 9.1 Hz), 7.00e7.24 (m, 5H, HAr),
7.35e7.54 (m, 6H, HAr), 7.54 (td,1H, HAr, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz), 7.64
(dd, 1H, H3, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz), 7.89 (dd, 1H, H8, 3J ¼ 7.6 Hz,
(75 MHz,) DMSO-d6:
d
¼ 18.1 (CH3), 20.0 (CH3), 37.9 (CH), 53.9
(CH), 126.7 (CIV), 128.3 (CH), 128.4 (CH), 128.9 (CH), 134.1 (CH),
138.8 (CIV), 161.8 (CO), 168.6 (CO); ESIeMS: m/z ¼ 220 (M þ H)þ;
Anal. Calc. For C12H13NO3: C, 65.74, H, 5.98, N, 6.39; Found: C,
65.59, H, 6.13, N, 6.22.
4J ¼ 1.6 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 26.4 (CH2), 35.2 (CH2),
35.4 (CH2), 45.9 (CH), 78.6 (OCH2),126.4 (CH),127.7 (CH),128.3 (CH),
128.5 (CH), 128.6 (CH), 128.7 (2CH), 128.9 (2CH), 129.3 (2CH), 129.5
(CIV),130.0 (2CH),130.6 (CIV),133.8 (CH),134.3 (CIV),137.6 (CIV),163.6
(CO), 166.8 (CO); ESIeMS: m/z ¼ 386 (M þ H)þ.
6.1.5.5. 2-Hydroxy-4-butylisoquinoline-1,3(2H,4H)-dione 5e,5e0. Pink
solid (75%). Mp 75e77 ꢃC; Keto form (5e): 90%. 1H NMR (300 MHz,
6.1.5. Preparation of the 2-hydroxisoquinoline-1,3(2H,4H)-dione
derivatives 5aem [19]
CDCl3):
d
¼ 0.72 (t, 3H, CH3, 3J ¼ 7.3 Hz), 1.00e1.18 (m, 4H, (CH2)b,c),
2.00 (dq, 1H, (CH2)a, 2J ¼ 13.5 Hz, 3J ¼ 5.1 Hz), 2.17 (dq, 1H, (CH2)a,
2J ¼ 13.5 Hz, 3J ¼ 5.1 Hz), 4.04 (tapp, 1H, CH, 3J ¼ 5.1 Hz), 7.28 (dd, 1H,
H5, 3J ¼ 7.6 Hz, 4J ¼ 1.3 Hz), 7.38 (td, 1H, HAr, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz),
7.58 (td, 1H, HAr, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz), 8.10 (dd, 1H, H8, 3J ¼ 7.6 Hz,
After boron tribromide or trichloride treatment, keto and enol
forms were isolated in most cases by precipitation of the organic
residues in dichloromethane and ethyl acetate, respectively. Keto
and enol forms could be undoubtedly identified by 1H and 13C
NMR measurements. The 1H NMR and 13C spectra of the keto
forms displayed peaks around 4.0e5.0 ppm and 40e50 ppm,
which could be attributed to the H4 proton and C4 carbon,
respectively. The signal characteristic of the H4 proton dis-
appeared for the enol forms whereas the signal characteristic of
the C4 carbon was shifted to 80e90 ppm. IR spectroscopy
corroborated the NMR data. There were two absorption bands at
1670 and 1725 cmꢀ1 (carbonyl functions) for the keto forms. In
contrast the IR spectra of the enol forms only displayed one
carbonyl vibration around 1625 cmꢀ1 and a new band (enol
4J ¼ 1.6 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.6 (CH3), 22.4 (CH2),
26.8 (CH2), 36.1 (CH2), 46.6 (CH, C4), 124.4 (CIV), 127.0 (CH), 127.8
(CH), 128.6 (CH), 134.1 (CH), 138.4 (CIV), 160.8 (CO), 169.0 (CO); Enol
form (5e0): 10%. 1H NMR (300 MHz, CDCl3): d ¼ 1.06 (t, 3H, CH3, 3J ¼
7.0 Hz), 1.20e1.28 (m, 4H, (CH2)b,c), 2.83 (dq, 1H, (CH2)a, 2J ¼ 12.7 Hz,
3J ¼ 4.5 Hz), 2.95 (dq, 1H, (CH2)a, 2J ¼ 12.7 Hz, 2J ¼ 4.1 Hz), 7.63 (td,
1H, HAr, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz), 7.81 (td, 1H, HAr, 3J ¼ 7.6 Hz, 4J ¼ 1.6
Hz), 7.96 (dd, 1H, H5, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz), 8.15 (dd, 1H, H8, 3J ¼ 7.6
Hz, 4J ¼ 1.6 Hz); 13C NMR (75 MHz, CDCl3): d ¼ 13.7 (CH3), 22.3
(CH2), 28.1 (CH2), 41.9 (CH2), 76.4 (CIV, C4), 125.8 (CIV), 127.5 (CH),
129.0 (CH), 129.7 (CH), 135.2 (CH), 138.9 (CIV), 159.4 (CO), 161.3 (CO);
ESIeMS: m/z ¼ 233 (M þ H)þ; Anal. Calc. For C13H15NO3: C, 66.94, H,
6.48, N, 6.00; Found: C, 67.14, H, 6.32, N, 5.85.
function) appeared at 1550 cmꢀ1
.
6.1.5.1. 2-Hydroxy-4-methylisoquinoline-1,3(2H,4H)-dione 5a. Light
green solid (55%). Keto form (5a): 60%. 1H NMR (300 MHz, acetone-
6.1.5.6. 2-Hydroxy-4-pentylisoquinoline-1,3(2H,4H)-dione 5f. White
solid (89%). Keto form (5f): 90%. Mp 84e85 ꢃC; 1H NMR (300 MHz,
d6):
d
¼ 1.65 (d, 3H, CH3, 3J ¼ 7.6 Hz), 4.12 (q, 1H, CH, 3J ¼ 7.6 Hz),
7.45e7.55 (m, 2H, HAr), 7.68 (td, 1H, HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz),
CDCl3):
d
¼ 0.70 (t, 3H, CH3, 3J ¼ 7.0 Hz),1.09 (m, 6H, CH2),1.95 (qd,1H,
8.09 (dd, 1H, H8, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, acetone-
CHeCH2eCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.1 Hz), 2.15 (qd, 1H, CHeCH2eCH2,
2J ¼ 13.5 Hz, 3J ¼ 5.1 Hz), 4.01 (t,1H, CH, 3J ¼ 5.1 Hz), 7.24e7.37 (m, 2H,
HAr), 7.55 (td, 1H, HAr, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz), 8.07 (dd, 1H, H8,
d6):
d
¼ 20.9 (CH3), 41.0 (CH, C4), 124.1 (CIV), 127.3 (CH), 127.5 (CH),
127.7 (CH), 133.7 (CH), 140.0 (CIV), 161.3 (CO), 170.1 (CO); ESIeMS: m/
z ¼ 192 (M þ H)þ; Anal. Calc. For C10H9NO3: C, 62.82, H, 4.74, N, 7.33;
Found: C, 62.66, H, 4.85, N, 7.42.
3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.7 (CH3),
22.0 (CH2), 24.2 (CH2), 31.2 (CH2), 36.2 (CH2), 46.5 (CH, C4),124.3 (CIV),
126.8 (CH), 127.6 (CH), 128.5 (CH), 134.0 (CH), 138.3 (CIV), 161.0 (CO),
169.2 (CO); ESIeMS: m/z ¼ 248 (M þ H)þ; Anal. Calc. For C14H17NO3:
C, 68.00, H, 6.93, N, 5.66; Found: C, 68.29, H, 6.75, N, 5.43.
6.1.5.2. 2-Hydroxy-4-ethylisoquinoline-1,3(2H,4H)-dione 5b. Beige oil
(75%). Keto form (5b): 100%. 1H NMR (300 MHz, CDCl3):
d
¼ 0.69 (t,
3H, CH3, 3J ¼ 7.3 Hz), 2.08 (dq, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 4.8 Hz), 2.35
(dq, 1H, CH2, 2J ¼ 13.5 Hz, 3J ¼ 5.4 Hz), 4.06 (tapp, 1H, CH, 3J ¼ 5.2 Hz),
7.31 (dd, 1H, H5, 3J ¼ 7.6 Hz, 4J ¼ 1.3 Hz), 7.42 (td, 1H, HAr, 3J ¼ 7.6 Hz,
4J ¼ 1.3 Hz), 7.65 (td, 1H, HAr, 3J ¼ 7.6 Hz, 4J ¼ 1.3 Hz), 8.14 (dd, 1H, H8,
3J ¼ 7.9 Hz, 4J ¼ 1.3 Hz), 9.38 (s,1H, N-OH); 13C NMR (75 MHz, CDCl3):
6.1.5.7. 4-Hexyl-2-hydroxy-isoquinoline-1,3(2H,4H)-dione 5g,5g0.
Yield (70%). Keto form (5g): 70%. Brown oil. 1H NMR (300 MHz,
CDCl3):
d
¼ 0.73 (t, 3H, CH3, 3J ¼ 7.3 Hz), 1.09e1.15 (m, 8H, CH2), 1.96
(qd, 1H, CHeCH2eCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.1 Hz), 2.15 (qd, 1H,
CHeCH2eCH2, 2J ¼ 13.5 Hz, 3J ¼ 5.1 Hz), 4.03 (t, 1H, CH, 3J ¼ 5.1 Hz),
7.27 (dd, 1H, H5, 3J ¼ 7.8 Hz, 4J ¼ 2.0 Hz), 7.36 (td, 1H, HAr, 3J ¼ 7.8 Hz,
4J ¼ 2.0 Hz), 7.57 (td,1H, HAr, 3J ¼ 7.8 Hz, 4J ¼ 2.0 Hz), 8.09 (dd,1H, H8,
d
¼ 9.1 (CH3), 29.6 (CH2), 47.4 (CH, C4), 124.6 (CIV), 127.1 (CH), 127.9
(CH), 128.9 (CH), 134.3 (CH), 138.0 (CIV), 160.7 (CO), 168.6 (CO);
ESIeMS: m/z ¼ 206 (M þ H)þ; Anal. Calc. For C11H11NO3: C, 64.38, H,
5.40, N, 6.83; Found: C, 64.56, H, 5.25, N, 6.62.
3J ¼ 7.8 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 13.9 (CH3),

544
M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
22.4 (CH2), 24.7 (CH2), 29.9 (CH2), 31.3 (CH2), 36.3 (CH2), 46.7 (CH, C4),
124.4 (CIV), 127.0 (CH), 127.7 (CH), 128.6 (CH), 134.1 (CH), 138.4 (CIV),
160.9 (CO), 169.1 (CO); ESIeMS: m/z ¼ 262 (M þ H)þ; Anal. Calc. For
C15H19NO3: C, 68.94, H, 7.33, N, 5.36; Found: C, 68.85, H, 7.43, N, 5.28.
Enol form (5g0): 30%. Beige solid. Mp 97e99 ꢃC; 1H NMR
6.1.5.11. 2-Hydroxy-4-(4-trifluoromethylbenzyl)isoquinoline-1,3(2H,-
4H)-dione 5k. Brown oil (36%). Keto form (5k): 100%. 1H NMR
(300 MHz, CDCl3):
d
¼ 3.38 (dd, 1H, CH2, 2J ¼ 13.4 Hz, 3J ¼ 4.0 Hz),
3.56 (dd, 1H, CH2, 2J ¼ 13.4 Hz, 3J ¼ 5.1 Hz), 4.36 (dd, 1H, CH,
3J ¼ 5.1 Hz, 3J ¼ 4.0 Hz), 6.84 (d, 2H, HAr, 3J ¼ 7.6 Hz), 7.23 (dd,1H, H5,
(300 MHz, acetone-d6):
d
¼ 0.82 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.10e1.30
3J ¼ 7.9 Hz, 4J ¼ 1.8 Hz), 7.33 (d, 2H, HAr, 3J ¼ 7.6 Hz), 7.43 (td, 1H, HAr
,
(m, 6H, CH2),1.52 (m, 2H, CH2), 2.68 (t,1H, CeCH2eCH2, 3J ¼ 7.0 Hz),
7.23 (td, 1H, HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz), 7.60 (m, 2H, HAr), 8.16 (dd,
1H, H8, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, acetone-d6):
3J ¼ 7.9 Hz, 4J ¼ 1.8 Hz), 7.58 (td,1H, HAr, 3J ¼ 7.9 Hz, 4J ¼ 1.8 Hz), 8.02
(dd, 1H, H8, 3J ¼ 7.9 Hz, 4J ¼ 1.8 Hz); 13C NMR (75 MHz, CDCl3):
1
d
¼ 42.4 (CH2), 48.0 (CH), 124.5 (q, CF3, JC-F ¼ 280.0 Hz), 125.4 (q,
3
2
d
¼ 13.9 (CH3), 22.1 (CH2), 23.5 (CH2), 28.5 (CH2), 29.1 (CH2), 31.2
2CH, JC-F ¼ 7.0 Hz), 125.8 (CIV), 126.9 (CH), 127.4 (q, CIV, JC-
4
(CH2), 89.5 (CIV), 121.4 (CH), 121.7 (CH), 122.0 (CIV), 126.8 (CH), 131.0
(CIV), 136.3 (CH), 146.9 (CO), 152.4 (CO); ESIeMS: m/z ¼ 262
(M þ H)þ; Anal. Calc. For C15H19NO3: C, 68.94, H, 7.33, N, 5.36;
Found: C, 69.12, H, 7.03, N, 5.42.
¼ 27.0 Hz), 127.7 (CH), 128.8 (CH), 129.1 (q, 2CH, JC-F ¼ 3.0 Hz),
F
130.2 (CH), 134.1 (CIV), 143.8 (CIV), 160.0 (CO), 167.2 (CO); ESIeMS:
m/z ¼ 336 (M þ H)þ; Anal. Calc. For C17H12F3NO3: C, 60.90, H, 3.61,
N, 4.18; Found: C, 61.1, H, 3.78, N, 3.99.
6.1.5.8. 4-Heptyl-2-hydroxy-isoquinoline-1,3(2H,4H)-dione 5h0. Beige
solid (62%). Enol form (5h0): 100%. Mp 121e123 ꢃC; 1H NMR
6.1.5.12. 2-Hydroxy-4-(2-phenyl)ethylisoquinoline-1,3(2H,4H)-dione
5l. Pink solid (70%). Mp 142e143 ꢃC; Keto form (5l): 100%. 1H NMR
(300 MHz, DMSO-d6):
d
¼ 0.79 (t, 3H, CH3, 3J ¼ 7.0 Hz), 1.07e1.28 (m,
(300 MHz, acetone-d6):
d
¼ 2.37e2.47 (m, 4H, (CH2)2), 4.21 (t, 1H,
3
8H, 4 CH2), 1.52 (m, 2H, CH2), 2.68 (t, 2H, CH2, J ¼ 6.8 Hz), 7.24 (td,
CH, 3J ¼ 7.0 Hz), 7.06e7.20 (m, 4H, HAr), 7.41e7.54 (m, 3H, HAr), 7.66
1H, HAr, 3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz), 7.60 (m, 2H, HAr), 8.16 (dd, 1H, H8,
(td, 1H, HAr
,
3J ¼ 7.6 Hz, 4J ¼ 1.2 Hz), 8.08 (dd, 1H, H8, 3J ¼ 7.6 Hz,
3J ¼ 8.0 Hz, 4J ¼ 2.0 Hz); 13C NMR (75 MHz, DMSO-d6):
d
¼ 13.8 (CH3),
4J ¼ 1.2 Hz); 13C NMR (75 MHz, acetone-d6):
d
¼ 32.0 (CH2), 38.4
21.9 (CH2), 22.0 (CH2), 28.3 (CH2), 28.6 (CH2), 28.8 (CH2), 31.3 (CH2),
89.3 (CIV, C4),121.4 (CH),121.6 (CH),121.9 (CIV) 136.3 (CH),126.7 (CH),
131.0 (CIV), 146.9 (CO), 152.4 (CO); ESIeMS: m/z ¼ 276 (M þ H)þ;
Anal. Calc. For C16H21NO3: C, 69.79, H, 7.69, N, 5.09; Found: C, 70.01,
H, 7.48, N, 4.98.
(CH2), 47.1 (CH), 126.8 (CH), 128.2 (CH), 128.5 (CH), 128.8 (CH), 129.1
(2CH), 129.2 (2CH), 129.5 (CIV), 130.0 (CIV), 134.6 (CH), 141.8 (CIV),
161.5 (CO), 169.3 (CO); ESIeMS: m/z ¼ 282 (M þ H)þ; Anal. Calc. For
C17H15NO3: C, 72.58, H, 5.37, N, 4.98; Found: C, 72.76, H, 5.17, N, 5.08.
6.1.5.13. 2-Hydroxy-4-(3-phenyl)propylisoquinoline-1,3(2H,4H)-di-
6.1.5.9. 4-Benzyl-2-hydroxy-isoquinoline-1,3(2H,4H)-dione 5i,5i0.
Yield (80%). Keto form (5i): 45%. Light yellow solid. Mp 140e142 ꢃC;
one 5m,5m0. Brown oil (75%). Keto form (5m): 70%. 1H NMR
(300 MHz, CDCl3):
d
¼ 1.52e2.13 (m, 6H, 3CH2), 4.02 (t, 1H, CH,
1H NMR (300 MHz, DMSO-d6):
d
¼ 3.36 (dd, 1H, CH2, 2J ¼ 8.9 Hz,
3J ¼ 5.1 Hz), 7.00e7.39 (m, 6H, HAr), 7.54 (m, 2H, HAr), 8.09 (dd, 1H,
3J ¼ 3.5 Hz), 3.45 (dd,1H, CH2, 2J ¼ 8.9 Hz, 3J ¼ 3.1 Hz), 4.56 (t,1H, CH,
3J ¼ 3.4 Hz), 6.70 (m, 2H, HAr), 7.08 (m, 3H, HAr), 7.45 (td, 1H, HAr,
3J ¼ 7.2 Hz, 4J ¼ 1.2 Hz), 7.53 (dd, 1H, H5, 3J ¼ 7.2 Hz, 4J ¼ 1.2 Hz), 7.68
(td, 1H, HAr, 3J ¼ 7.2 Hz, 4J ¼ 1.2 Hz), 7.86 (dd, 1H, H8, 3J ¼ 7.2 Hz,
H8, 3J ¼ 7.6 Hz, 4J ¼ 1.6 Hz); 13C NMR (75 MHz, CDCl3):
d
¼ 26.2
(CH2), 35.1 (CH2), 35.4 (CH2), 46.2 (CH),126.7 (CH),127.6 (CH),128.0
(2CH), 128.1 (2CH), 128.4 (CH), 128.8 (CIV), 128.9 (CIV), 136.2 (CIV),
137.9 (CH),141.0 (CH),160.8 (CO),168.8 (CO); Enol form (5m0): 30%.
4J ¼ 1.2 Hz), 10.40 (s, 1H, OH); 13C NMR (75 MHz, DMSO-d6):
d
¼ 41.1
1H NMR (300 MHz, CDCl3):
d
¼ 1.52e2.13 (m, 6H, 3CH2), 7.00e7.39
(CH2), 47.5 (CH), 125.2 (CIV), 126.6 (CH), 127.7 (CH), 127.8 (CH), 127.9
(2CH), 129.0 (2CH), 129.6 (CH), 133.3 (CH), 135.9 (CIV), 137.6 (CIV),
160.9 (CO), 168.9 (CO); ESIeMS: m/z ¼ 268 (M þ H)þ; Anal. Calc. For
C16H13NO3: C, 71.90, H, 4.90, N, 5.24; Found: C, 71.78, H, 4.99, N, 5.15.
Enol form (5i0): 55%. Brown solid. Mp 135e137 ꢃC; 1H NMR
(m, 8H, HAr), 8.38 (dd, 1H, H8, 3J ¼ 7.9 Hz, 4J ¼ 2.0 Hz); 13C NMR
(75 MHz, CDCl3):
d
¼ 23.5 (CH2), 30.3 (CH2), 33.5 (CH2), 76.5 (CIV),
121.7 (CIV), 123.7 (CH), 124.2 (CH), 125.6 (CH), 125.7 (2CH), 126.7
(CH), 128.4 (2CH), 131.9 (CIV), 136.2 (CIV), 141.6 (CH), 145.2 (COH),
151.2 (CO); ESIeMS: m/z ¼ 296 (M þ H)þ; Anal. Calc. for C18H17NO3:
C, 73.20, H, 5.80, N, 4.74; Found: C, 72.99, H, 5.25, N, 5.01.
(300 MHz, DMSO-d6):
d
¼ 3.35 (d, 1H, CH2, 2J ¼ 13.0 Hz), 3.56 (d, 1H,
CH2, 2J ¼ 13.0 Hz), 7.10e7.59 (m, 8H, HAr), 7.98 (dd,1H, H8, 3J ¼ 7.2 Hz,
4J ¼ 1.2 Hz); 13C NMR (75 MHz, DMSO-d6):
¼ 29.3 (CH2), 88.2 (CIV),
d
121.6 (CIV), 122.3 (CH), 122.7 (CH), 125.9 (CH), 126.7 (CH), 127.9 (2CH),
128.4 (2CH), 131.1 (CIV), 136.3 (CIV), 140.7 (CH), 147.7 (CO), 152.7 (CO);
ESIeMS: m/z ¼ 268 (M þ H)þ; Anal. Calc. For C16H13NO3: C, 71.90, H,
4.90, N, 5.24; Found: C, 71.75, H, 4.67, N, 5.32.
6.2. Docking procedure
Previous work revealed that the 2-hydroxyisoquinoline-1,3
(2H,4H)-dione scaffold complexes magnesium as the enol or
enolate form [19]. Preliminary calculations using the SPARC
online calculator [38] indicate that such enols are deprotonated in
aqueous media at physiological pH, hence we chose to model our
ligands as the enolate form. All ligands were created and mini-
mized at the B3LYP/6-31G* level using the Gaussian 03 package
[39]. The study was based on the 3L2T PDB structure containing 2
magnesium cations. The co-crystallized ligand was extracted and
the protein was prepared by adding hydrogens and removing
water molecules and irrelevant heteroatoms in Accelrys DS
Visualizer 2.5.5 [40]. Docking calculations were carried out using
the CCDC GOLD docking suite [26] with the active site defined as
6.1.5.10. 2-Hydroxy-4-(4-methylbenzyl)isoquinoline-1,3(2H,4H)-di-
one 5j,5j0. Beige solid (91%). Mp 138e139 ꢃC; Keto form (5j): 77%.
1H NMR (300 MHz, DMSO-d6):
d
¼ 2.14 (s, 3H, CH3), 3.30 (dd, 1H,
CH2, 2J ¼ 13.5 Hz, 3J ¼ 5.0 Hz), 3.42 (dd, 1H, CH2, 2J ¼ 13.5 Hz,
3J ¼ 4.6 Hz), 4.51 (t,1H, CH, 3J ¼ 4.8 Hz), 6.57 (d, 2H, HAr, 3J ¼ 7.6 Hz),
6.86 (d, 2H, HAr, 3J ¼ 7.6 Hz), 7.39e7.48 (m, 2H, HAr), 7.67 (td,1H, HAr
,
C
3J ¼ 7.6 Hz, 4J ¼ 1.2 Hz), 7.86 (dd, 1H, H8, 3J ¼ 7.6 Hz, 4J ¼ 1.2 Hz); 13
NMR (75 MHz, DMSO-d6):
d
¼ 20.5 (CH3), 40.6 (CH2), 47.5 (CH),
125.1 (CIV), 127.3 (CH), 127.5 (CH), 127.8 (CH), 128.5 (2CH), 128.8
(2CH), 132.7 (CIV), 133.2 (CH), 135.5 (CIV), 137.6 (CIV), 160.9 (CO),
168.9 (CO). Enol form (5j0): 23%. 1H NMR (300 MHz, DMSO-d6):
ꢀ
a sphere containing all atoms within 15 A of the X-ray ligand
d
¼ 2.20 (s, 3H, CH3), 4.01 (s, 2H, CH2), 7.02 (d, 2H, HAr, 3J ¼ 7.6 Hz),
raltegravir. The CHEMPLP fitness function [27] was used at default
settings. After manual editing of atom and bond types in mol2
files, all ligands were submitted to 100 docking runs using
7.13 (d, 2H, HAr, 3J ¼ 7.6 Hz), 7.39e7.55 (m, 3H, HAr), 8.16 (dd,1H, H8,
3J ¼ 7.0 Hz, 4J ¼ 1.2 Hz); 13C NMR (75 MHz, DMSO-d6):
d
¼ 83.9
ꢀ
(CIV), the only detectable peak of this species; ESIeMS: m/z ¼ 282
(M þ H)þ; Anal. Calc. for C17H15NO3: C, 72.58, H, 5.37, N, 4.98;
Found: C, 72.39, H, 5.49, N, 4.76.
a 0.75 A RMSD clustering. The resulting docking poses were
analyzed in DS Visualizer and selected poses were rendered using
POV-Ray [41].

M. Billamboz et al. / European Journal of Medicinal Chemistry 46 (2011) 535e546
545
6.3. Biological procedures
European TRIoH Consortium is gratefully acknowledged. The Mass
Spectrometry facility used in this study was funded by the Euro-
pean Community (FEDER), the Région Nord Pas-de-Calais (France),
the CNRS, and the Université des Sciences et Technologies de Lille.
We are grateful to Martine Michiels, Nam Joo Vanderveken, and
Barbara Van Remoortel for excellent technical assistance.
RNase H and integrase inhibition assays, in vitro anti-HIV and
drug susceptibility assays were performed according previously
reported methods [19].
6.3.1. Integrase inhibition
To determine the susceptibility of the HIV-1 integrase enzyme
to different compounds, an enzyme-linked immunosorbent assay
was used. This assay uses an oligonucleotide substrate in which
one oligo (50-ACTGCTAGAGATTTTCCACACTGACTAAAAGGGTC-30) is
labeled with biotin on the 30 end and in which the other oligo is
labeled with digoxigenin at the 50 end. For the overall integration
assay, the second 50-digoxigenin-labeled oligo is 50-GACCCTTT-
TAGTCAGTGTGGAAAATCTCTAGCAGT-30. The integrase was diluted
Appendix. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.ejmech.2010.11.033.
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