Structure-activity relationships of novel 2-substituted quinazoline antibacterial agents

Article abstract of DOI:10.1021/jm9903500

High-throughput screening of in-house compound libraries led to the discovery of a novel antibacterial agent, compound 1 (MIC: 12-25 μM against S. pyogenes). In an effort to improve the activity of this active compound, a series of 2-substituted quinazolines was synthesized and evaluated in several antibacterial assays. One such compound (22) displayed improved broad- spectrum antibacterial activity against a variety of bacterial strains. This molecule also inhibited transcription/translation of bacterial RNA, suggesting a mechanism for its antibiotic effects. Structure-activity relationship studies of 22 led to the synthesis of another 24 compounds. Although some of these molecules were found to be active in bacterial growth assays, none were as potent as 22. Compound 22 was tested for its ability to cure a systemic K. pneumonia infection in the mouse and displayed moderate effects compared with a control antibiotic, gentamycin.

Full text of DOI:10.1021/jm9903500

J . Med. Chem. 1999, 42, 4705-4713
4705
Str u ctu r e-Activity Rela tion sh ip s of Novel 2-Su bstitu ted Qu in a zolin e
An tiba cter ia l Agen ts
Pei-Pei Kung,* Martin D. Casper, Kimberley L. Cook, Laura Wilson-Lingardo, Lisa M. Risen,
Timothy A. Vickers, Ray Ranken, Lawrence B. Blyn, J acqueline R. Wyatt, P. Dan Cook, and David J . Ecker
Ibis Therapeutics, a Division of Isis Pharmaceuticals, and Medicinal Chemistry, Isis Pharmaceuticals, 2292 Faraday Avenue,
Carlsbad, California 92008
Received J uly 8, 1999
High-throughput screening of in-house compound libraries led to the discovery of a novel
antibacterial agent, compound 1 (MIC: 12-25 µM against S. pyogenes). In an effort to improve
the activity of this active compound, a series of 2-substituted quinazolines was synthesized
and evaluated in several antibacterial assays. One such compound (22) displayed improved
broad-spectrum antibacterial activity against a variety of bacterial strains. This molecule also
inhibited transcription/translation of bacterial RNA, suggesting a mechanism for its antibiotic
effects. Structure-activity relationship studies of 22 led to the synthesis of another 24
compounds. Although some of these molecules were found to be active in bacterial growth assays,
none were as potent as 22. Compound 22 was tested for its ability to cure a systemic K.
pneumonia infection in the mouse and displayed moderate effects compared with a control
antibiotic, gentamycin.
In tr od u ction
The spread of antibiotic resistance among pathogenic
bacteria has become a serious problem for the clinical
management of infectious diseases and has resulted in
a clear need for novel antibacterial agents other than
analogues of existing antibiotics.1 In an effort to identify
such novel agents, our antibacterial program routinely
screens large in-house libraries of small synthetic
compounds for active leads. Compound 1 (Figure 1,
Table 1) was indicated from these screening efforts to
have moderate antibacterial activity against the Gram-
positive bacterium, Streptococcus pyogenes. Intrigued by
the novel structure of 1, we subsequently conducted
structure-activity relationship (SAR) studies to (1)
define the functionalities responsible for the observed
antibacterial activity and (2) further improve the anti-
biotic potency of the molecule. In this work, we report
on the initial SAR studies of compound 1 which led to
improved broad-spectrum antibacterial activity.
F igu r e 1. Structure of antibacterial lead from high-through-
put screening.
Ta ble 1. SAR of Compound 1 with Fixed “C” Portion
S. pyogenes (#14289) E. coli imp-
compd
R
B
(µM)
(µM)
Resu lts a n d Discu ssion
1
7
35
36
37
Q
Q
Boc
H
Pip
HN-NH
Pip
12-25
>25
>50
>25
>25
>50
Inspection of the chemical structure of 1 suggested
that the compound could be divided into three sub-
units: the quinazoline fragment (A), the 4-aminopip-
eridine linker (B), and the pyrazine moiety (C) (Figure
1). Initial SAR studies were performed by modification
of the parent compound to determine if any of the
subunits which comprise 1 displayed antibacterial
activity. As seen in Table 1, replacement of the 4-amino-
piperidine linker B with a simple hydrazine moiety
resulted in complete loss of antibacterial activity (com-
pound 7). Replacement of the quinazoline fragment (A)
with either Boc, hydrogen, or benzyl functionalities
(compounds 35-37, respectively) resulted in similar loss
of activity. Therefore, we concluded that both A and B
>50
>25
>25
>50
Pip
PhCH2 Pip
fragments were required for antibacterial activity, and
subsequent SAR studies were conducted with molecules
containing such moieties.
10.1021/jm9903500 CCC: $18.00 © 1999 American Chemical Society
Published on Web 10/14/1999

4706 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 22
Ta ble 2. SAR of Compound 1 with Fixed “A” and “B” Portions
Kung et al.
Ta ble 3. SAR with Fixed “B” Portion
S. pyogenes (#14289) E. coli imp-
compd
A
R
(µM)
(µM)
4
5
22
46
48
49
50
Q
Q
Q
CH3
C(CH3)3
H
5-25
3-6
>25
>25
>25
>25
>25
5-25
6-12
0.4-2
>25
S. pyogenes E. coli imp-
compd
X
Y
Z
W
R
(#14289) (µM)
(µM)
PhCH2 CH3
1
2
N
N
Cl
H
H
NH2 CH3
NH2 CH3
12-25
>50
>25
PhCH2 C(CH3)3
>25
N
N
>50
H
C(CH3)3
H
>25
>25
3
CH N
H
CH3
25-50
5-25
3-6
>50
PhCH2
4
CH CH H
CH CH H
CH CH NO2
H
CH3
C(CH3)3
5-25
6-12
25-50
>100
>25
5
H
H
6
C(CH3)3
50-100
>100
>25
>50
>20
18
19
20
21
22
N
N
N
N
Cl
H
NH2
NH2
H
H
H
H
H
H
CH N
H
>50
>20
CH CH NO2
CH CH H
H
H
>25
0.4-2
benzoic acids/esters without negatively affecting their
antibacterial activity.
Modifications to the pyrazine moiety present in 1 (the
C fragment) were then undertaken (Table 2). Removal
of the 6-chloro substituent from the pyrazine ring
resulted in diminished antibacterial activity relative to
1 (compound 2). However, removal of the 3-amino group
and substitution of a CH moiety for the nitrogen at the
1 position of the dehalogenated pyrazine returned
antibacterial activity to nearly that displayed by com-
pound 1 (compare pyridine 3 with 1). Additional CH for
N substitution further improved antibacterial activity
relative to 1 when the resulting compound (4) was tested
against both S. pyogenes and Escherichia coli, imp-
bacterial strains. This dual-strain antibiotic effect could
be further improved by incorporation of a tert-butyl ester
moiety into the compound structure (5) but was im-
paired when a nitro group was introduced on the
benzene C ring (compound 6).
We next attempted modification of the quinazoline A
fragment contained in the most active compounds 5 and
22 (Table 4). Replacement of the quinazoline moiety of
either 5 or 22 with simple (less functionalized) aromatic
groups resulted in loss of antibacterial activity (compare
compounds 8, 11, and 12 with 5 and compare 23, 26,
and 27 with 22). Variation of the linking functionality
between one such simple aromatic group (naphthyl) and
the 4-aminopiperidine moiety did not restore the lost
antibacterial activity (compounds 9, 10, 24, and 25).
Modification of the 4-amino substituent on the quinazo-
line ring predominately afforded less active antibacterial
agents (compare 13-15 with 5 and compare 28-31 with
22) although amine substitution was tolerated in one
case (compare 16 to 5). Similar reduction in antibacte-
rial potency was observed when the 6- and 7-methoxy
substituents were removed from the quinazoline ring
(compounds 17 and 32).
In addition to the molecules described above bearing
C rings with ester moieties, we also examined the
corresponding carboxylic acid-containing compounds
(compounds 18-22, Table 2). In most cases, replace-
ment of the ester functional group with the free acid
resulted in loss of or no improvement in antibacterial
activity (compare 18 with 1, 19 with 2, and 20 with 3).
However, in the example of compound 5, such acid-for-
ester substitution resulted in reduced activity against
S. pyogenes but substantially improved activity against
E. coli, imp- (compound 22). Therefore, compounds
containing C rings comprised of substituted benzoic
acids and/or esters were examined in greater detail with
an additional SAR study.
Having completed the above SAR studies, three of the
most potent compounds (4, 5, and 22) were selected to
be screened against additional bacterial strains as
shown in Table 5. In these assays, 22 displayed moder-
ate activity against the pathogenic bacteria, Klebsiella
pneumoniae (6-12 µM) and Staphylococcus aureus (6-
12 µM), but was inactive against several other strains.
Compounds 4 and 5 exhibited somewhat less potent
broad-spectrum activity than 22, and the latter molecule
was therefore selected for in vivo testing. In the event,
compound 22 displayed moderate antibacterial activity
in mice infected with K. pneumoniae and afforded a 40%
survivor rate when administrated at 100 mg/kg. This
result was compared with that provided by the known
antibiotic, gentamycin, which afforded a 70% survivor
rate when dosed at 3 mg/kg.
Several truncated molecules related to 4, 5, and 22
were examined to confirm that the antibacterial activity
exhibited by these compounds was related to all three
subunits (A, B, and C, Figure 1) of the molecules (Table
3). Replacement of the quinazoline moiety (A fragment)
of 4, 5, and 22 with a benzyl group resulted in loss of
antibacterial activity (compounds 46, 48, and 50, re-
spectively). A similar loss in activity was noted for a
molecule related to 5 which contained no A fragment
(compound 49). Thus, as was observed for the pyrazine-
containing molecules above, the quinazoline fragment
could not be removed from compounds incorporating
In addition, compound 22 inhibited a luciferase-based
bacterial transcription/translation assay with an IC50
) 12-12.5 µM. Further testing of compound 22 in the
transcription/translation assay showed that the re-
sponse was dose-dependent (Figure 2a) and that the
compound did not directly inhibit luciferase (data not
shown). This inhibition was specific to bacterial tran-
scription/translation as shown by the inability of the
compound to effectively inhibit a rabbit reticulocyte

SAR of Novel 2-Substituted Quinazolines
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 22 4707
Ta ble 4. SAR of Compounds 5 and 22 with Different “A” Portion
S. pyogenes
(#14289) (µM)
E. coli imp-
(µM)
compd
A
L
R
5
8
Q
C(CH3)3
3-6
6-12
>25
Naph
Naph
Naph
Pyr
C(CH3)3
>25
9
SO2
CO
C(CH3)3
>25
>25
10
11
12
13
14
15
16
17
22
23
24
25
26
27
28
29
30
31
32
C(CH3)3
>25
>25
C(CH3)3
>25
>25
Bnim
QH
QME
QOH
QPH
QDME
Q
Naph
Naph
Naph
Pyr
Bnim
QH
C(CH3)3
>100
>20
>100
>20
C(CH3)3
C(CH3)3
<100a
>100
2.5-5
<100a
>25
<100a
>100
10-20
<100a
0.4-2
>25
C(CH3)3
C(CH3)3
C(CH3)3
H
H
H
H
H
H
H
H
H
H
H
>25
SO2
CO
>25
>25
>25
>25
>25
>25
>25
>25
>20
>20
QME
QOH
QPH
QDME
>20
>20
>20
>20
>20
>20
>100
>100
a
About 90% inhibition at 100 µM.
Ta ble 5. Comparison of Lead Compounds in Broad-Spectrum Antibacterial Screening
K. pneumoniae
(#13883)
(µM)
E. coli
(#25922)
(µM)
S. pyogenes
(#49399)
S. aureus
(#13709)
(µM)
E. faecalis
(#29212)
(µM)
compd
R
(µM)
4
5
22
CH3
C(CH3)3
H
>100
>100
6-12
>100
>100
60-80
5-25
6-12
>25
>100
>100
6-12
20-40
6-12
>100
transcription/translation system (Figure 2b, IC50 ) 190
µM). To provide information about the specific mecha-
nism of action of compound 22, we looked at its ability
to inhibit incorporation of [3H]UTP into RNA (Figure
3). Even at the highest doses, there was no effect on
RNA synthesis, indicating that the compound worked
at the translational level. Interestingly, incorporation
of tritiated amino acids into luciferase was not signifi-
cantly inhibited by compound 22. This result suggested
that compound 22 might function by allowing misin-
corporation of amino acids into the luciferase protein.
Indeed, compound 22 provided a 50% signal increase
in an amino acid misincorporation1d,2 experiment when
tested at 500 µM. The difference in compound concen-
tration required to see results in the two assays may
be due, in part, to the high sensitivity of luciferase to
small changes in protein sequence and the relatively
high tolerance to amino acid substitution by the type of
misincorporation assay used in this work. Together,
these results suggest that the antibacterial effects
exhibited by 22 may be due to a mechanism in which
the compound causes misincorporation during transla-
tion.
To conclude, this work describes the initial SAR study
of quinazoline-containing antibacterial agents which
resulted in the identification of several moderately
potent broad-spectrum antibacterial compounds of novel
structure. One such compound (22) was active in an in

4708 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 22
Kung et al.
general, the B-C fragments of these molecules were
assembled using either aromatic nucleophilic substitu-
tion chemistries (SNAr)4 or palladium-catalyzed cross-
coupling methods.5 An example of the former method-
ology is given by the synthesis of compounds 1-3 and
18-20 (Scheme 1). Thus, SNAr coupling of commer-
cially available pyrazine 34 with the known6 Boc-
protected 4-aminopiperidine (41) afforded the B-C
product 35 in moderate yield. Removal of the Boc moiety
and subsequent coupling of the resulting amine hydro-
chloride salt (36) with 4-amino-2-chloro-6,7-dimethoxy-
quinazoline then provided the antibacterial agent 1.7
The carboxylic acid (18) corresponding to 1 was pre-
pared by basic hydrolysis of the latter.
A second example of SNAr synthetic methodology is
provided by the preparation of compounds 2, 3, 19, and
20 (Scheme 1). In this example, commercially available
4-amino-1-benzylpiperidine (45) was derivatized via
SNAr chemistries with either pyrazine 34 or pyridine
33 to provide the corresponding coupling products (37
and 39, respectively). These intermediates were deben-
zylated, and the resulting free amines (38 and 40) were
condensed with 4-amino-2-chloro-6,7-dimethoxyquinazo-
line to provide antibacterial agents 2 and 3 in moderate
yields. As described for the preparation of compound 18
above, basic hydrolysis of the ester moiety present in 2
and 3 afforded the corresponding carboxylic acids 19 and
20, respectively.
F igu r e 2. Specificity of compound 22 for inhibition of bacterial
transcription/translation. (a) Compound 22 was tested at
increasing doses for its ability to inhibit a bacterial cell-free
coupled transcription/translation system. The IC50 of com-
pound 22 in this system was ∼12-12.5 µM. (b) Compound 22
was tested at increasing doses for its ability to inhibit a rabbit
reticulocyte cell-free coupled transcription/translation system.
The IC50 of compound 22 in this system was ∼190 µM.
A final example of the SNAr synthetic approach is
given by the preparation of compounds 6 and 21
(Scheme 2). Thus, SNAr coupling of protected piperidine
41 with the chlorinated benzoic acid ester 42 prepared
by reacting the corresponding acid chloride with tert-
butyl alcohol provided intermediate 43 in moderate
yield. Boc deprotection was then effected in the presence
of the tert-butyl ester moiety,8 and the resulting amine
hydrochloride salt was condensed with 4-amino-2-chloro-
6,7-dimethoxyquinazoline to afford compound 6. The
carboxylic acid corresponding to 6 (21) was subsequently
prepared by acidic deprotection of the tert-butyl ester
moiety.
An alternate method of assembling the B-C frag-
ments of the compounds described in this work involved
use of palladium-catalyzed cross-coupling methodology.5
An example of such an alternative synthetic method is
given in Scheme 3 by the preparation of compounds 4,
5, and 22. Thus, Pd-mediated coupling of 4-bromoben-
zoic acid methyl ester with 4-amino-1-benzylpiperidine
(45) provided either methyl ester 46 or tert-butyl ester
48 depending on the reaction conditions.10 The benzyl
protecting group in both products was subsequently
removed, and the resulting amines (47 and 49) were
condensed with 4-amino-2-chloro-6,7-dimethoxyquinazo-
line to afford compounds 4 and 5 in moderate yields.
The carboxylic acid 22 was prepared by acidic depro-
tection of compound 5.
F igu r e 3. Effect of compound 22 on incorporation of [3H]UTP
into cellular RNA. The effect of compound 22 on bacterial
transcription was measured by the incorporation of [3H]UTP
into cellular RNA. Increasing concentrations of compound 22
were compared to a rifampicin control. Rifampicin had an IC50
of 1 µM, while compound 22 had no detectable IC50 in this
assay.
Scheme 4 illustrates the preparation of several com-
pounds described in this work which were synthesized
by modifications of the methods depicted above. Thus,
the key intermediate 49 (described in Scheme 3 above)
was independently derivatized with 2-naphthalene-
sulfonyl chloride or 2-naphthoyl chloride to afford
coupling products 9 and 10, respectively. The tert-butyl
esters present in these compounds were subsequently
vivo model of bacterial infection and was suggested to
exert its antibacterial effects by altering RNA transla-
tion. Additional studies of these novel antibacterial
agents will be reported in due course.3
Ch em istr y
The synthetic routes used to prepare the compounds
described in this work are depicted in Schemes 1-4. In

SAR of Novel 2-Substituted Quinazolines
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 22 4709
Sch em e 1a
a
Reagents and conditions: (a) 5.5 equiv N,N′-diisopropylethylamine, DMF, 25 °C, 12 h, 78-99%; (b) HCl in 1,4-dioxane, 25 °C, 12 h;
(b′) 10 equiv ammonium formate, ethanol, 80 °C, 12 h, quantitative yield 86%; (c) 1.0 equiv 4-amino-2-chloro-6,7-dimethoxyquinazoline,
isoamyl alcohol, 120 °C, 12 h, 49-68%; (d) potassium hydroxide, 1:9 MeOH:H2O, 85 °C, 12 h, HCl, 93-99%.
Sch em e 2a
a
Reagents and conditions: (a) 2.7 equiv N,N′-diisopropylethylamine, DMF, 110 °C, 24 h, 55%; (b) HCl in 1,4-dioxane, 25 °C, 12 h, 59%;
(c) 1.0 equiv 4-amino-2-chloro-6,7-dimethoxyquinazoline, n-pentanol, 120 °C, 12 h, 64%; (d) TFA, 25 °C, 12 h, 78%.
Sch em e 3a
a
Reagents and conditions: (a) 0.003 equiv Pd2(dba)3, 0.01 equiv (()-BINAP, 1.3 equiv cesium carbonate, toluene, 80 °C, 12 h, 35%;
0.003 equiv Pd2(dba)3, 0.01 equiv (()-BINAP, 2.6 equiv sodium tert-butoxide, toluene, 80 °C, 12 h, 49%; (b) 10 equiv ammonium formate,
ethanol, 80 °C, 12 h, 92-94%; (c) 1.0 equiv 4-amino-2-chloro-6,7-dimethoxyquinazoline, tert-butyl alcohol, 120 °C, 12 h, 59-83%; (d) HCl
in 1,4-dioxane, 25 °C, 12 h, 91%.
in the literature.11,12 Sodium borohydride reduction of 2,4-
removed to provide carboxylic acids 24 and 25. Alter-
natively, 49 could be coupled with a variety of hetero-
cycles (2-bromonaphthalene, 2-bromopyrimidine, and
2-chloro-5-methoxybenzimidazole) to give products 8,
dichloro-6,7-dimethoxyquinazoline gave QH in about 37%
yield,11 and compound 52 (2-chloro-4-hydroxyl-6,7-dimethoxy-
quinazoline) was obtained as a major side product due to
sodium hydroxide contamination in the commercially available
sodium borohydride. 2,4-Dichloro-6,7-dimethoxyquinazoline
11, and 12 in moderate yields. As described above, the
tert-butyl esters present in these molecules were sub-
sequently removed to afford carboxylic acids 23, 26, and
27, respectively.
was treated with sodium methoxide to give QME in quantita-
tive yield.12 Compounds QPH and QDME were gifts from Dr.
Karl Hargrave of Boehringer Ingelheim, and their preparation
procedures are reported in the literature.13,14 SNAr chemistry
similar to that depicted in Scheme 3 was used to prepare
compounds 13, 14, 16, and 17 which correspond to compounds
QH, QME, QPH, and QDME, respectively. Compound 15 was
obtained in the course of synthesizing compound 14 through
in situ hydrolysis of the quinazoline 4-methoxy group.15
Compounds 13-17 were converted to the corresponding car-
boxylic acid derivatives 28-32 by treatment with trifluoro-
acetic acid.
Exp er im en ta l Section
Gen er a l. Chemicals, reagents, and solvents were purchased
and used as received unless otherwise noted. Flash column
chromatography16 was performed using silica gel 60 (Merck
Art 9385). Proton and carbon NMR spectra were recorded at
200 MHz utilizing a Varian Gemini spectrometer. Chemical
shifts are reported in ppm (δ) downfield relative to internal
tetramethylsilane, and coupling constants are given in Hertz.
2-Chloro-4-substituted-quinazolines (QH, QME) were pre-
pared from 2,4-dichloro-6,7-dimethoxyquinazoline as described
Gen er a l P r oced u r e for Cou p lin g w ith 4-Am in o-2-
ch lor o-6,7-d im eth oxyqu in a zolin e a n d Der iva tives. Com-

4710 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 22
Kung et al.
Sch em e 4a
a
Reagents and conditions: (a) 3 equiv 2-naphthalenesulfonyl chloride, 5 equiv triethylamine, CH2Cl2, 25 °C, 12 h, 93%; 3 equiv
2-naphthoyl chloride, 5 equiv triethylamine, CH2Cl2, 25 °C, 12 h, 50%; (b) 1 equiv 2-bromonaphthalene, 0.005 equiv Pd2(dba)3, 0.014
equiv (()-BINAP, 2.6 equiv sodium tert-butoxide, toluene, 80 °C, 12 h, 59%; 1 equiv 2-bromopyrimidine, tert-butyl alcohol, 25 °C, 12 h,
89%; 1 equiv 2-chloro-5-methoxybenzimidazole, n-pentanol, 25 °C, 12 h, 83%; (c) HCl in 1,4-dioxane, 25 °C, 12 h; (d) TFA, 25 °C, 12 h.
pound 49 (36, 38, 40, 44, 47) was added to a solution of
4-amino-2-chloro-6,7-dimethoxyquinazoline or derivatives (0.9
equiv) in isoamyl alcohol (3-methyl-1-butanol) or n-pentanol
(10 mL/mmol) at 25 °C. The mixture was then stirred at 120
°C for 12 h, cooled to room temperature, and filtered and rinsed
with acetone to give the desired compounds (1-6, 11-14, 16,
17).
3-Am in o-5-[1-(4-a m in o-6,7-d im eth oxyqu in a zolin -2-yl)-
p ip er id in -4-yla m in o]-6-ch lor op yr a zin e-2-ca r boxylic a cid
m eth yl ester (1): 1H NMR (CDCl3) δ 6.93 (s, 1H), 6.82 (s,
1H), 5.44 (d, 1H, J ) 7.8), 5.21 (br s, 2H), 4.77 (d, 2H, J )
13.7), 4.19 (m, 1H), 3.97 (s, 3H), 3.92 (s, 3H), 3.90 (s, 3H), 3.12
(t, 2H, J ) 11.3), 2.12 (d, 2H, J ) 12.6), 1.56 (m, 2H); 13C NMR
(CDCl3) δ 166.6, 160.7, 158.4, 155.6, 155.4, 150.8, 149.6, 146.1,
121.5, 110.6, 105.8, 102.8, 101.7, 56.3, 56.1, 51.9, 48.9, 43.0,
31.8; HRMS (FAB) m/z 621.0766 (M + Cs)+ (C21H25N8O4Cl
requires 621.0742). Anal. (C21H25N8O4Cl‚1/2HCl‚1/4CH3OH) C,
H, N.
(d, 2H, J ) 13.2), 3.87 (s, 3H), 3.83 (s, 3H), 3.82 (m, 1H), 3.73
(s, 3H), 3.43 (m, 2H), 2.05 (m, 2H), 1.44 (m, 2H); 13C NMR
(CDCl3) δ 166.3, 161.4, 155.2, 151.7, 151.0, 146.7, 136.0, 131.0,
115.8, 111.3, 104.9, 101.6, 99.2, 56.2, 56.0, 51.2, 47.9, 43.4, 31.0.
Anal. (C23H27N5O4‚1HCl) C, H, N.
4-[1-(4-Am in o-6,7-d im eth oxyqu in a zolin -2-yl)p ip er id in -
4-yla m in o]ben zoic a cid ter t-bu tyl ester (5): 1H NMR
(DMSO) δ 12.20 (br s, 1H), 8.66 (br, 2H), 7.76 (s, 1H), 7.66 (d,
2H, J ) 8.7), 7.53 (s, 1H), 6.67 (d, 2H, J ) 8.7), 6.51 (d, 1H, J
) 7.4), 4.56 (d, 2H, J ) 13.6), 3.90 (s, 3H), 3.86 (s, 3H), 3.76
(m, 1H), 3.46 (m, 2H), 2.07 (d, 2H, J ) 11.1), 1.52 (s, 9H), 1.44
(m, 2H); 13C NMR (DMSO) δ 165.3, 161.4, 155.3, 151.4, 151.1,
146.8, 136.4, 131.0, 117.8, 111.3, 105.0, 101.6, 99.2, 79.1, 56.3,
56.1, 48.0, 43.4, 31.0, 28.1; HRMS (FAB) m/z 480.2616 (M +
H)+ (C26H33N5O4 requires 480.2611). Anal. (C26H33N5O4‚1HCl)
C, H, N.
4-[1-(4-Am in o-6,7-d im eth oxyqu in a zolin -2-yl)p ip er id in -
4-yla m in o]-3-n itr oben zoic a cid ter t-bu tyl ester (6): 1H
NMR (DMSO) δ 12.23 (s, 1H), 8.89 (s, 1H), 8.65 (s, 1H), 8.56
(s, 1H, J ) 2.0), 8.23 (d, 1H, J ) 7.8), 7.94 (d, 1H, J ) 9.2),
7.74 (s, 1H), 7.55 (s, 1H), 7.34 (d, 1H, J ) 9.3), 4.62 (d, 2H, J
) 13.3), 4.15 (m, 1H), 3.87 (s, 3H), 3.84 (s, 3H), 3.35 (t, 2H, J
) 11.6), 2.10 (d, 2H, J ) 11.3), 1.74 (m, 2H), 1.53 (s, 9H); 13C
NMR (DMSO) δ 163.5, 161.4, 155.2, 151.2, 146.8, 146.2, 136.3,
135.8, 130.6, 128.2, 117.9, 115.1, 104.9, 101.6, 99.1, 80.8, 56.2,
56.0, 48.8, 43.5, 30.5, 27.8; HRMS (FAB) m/z 525.2456 (M +
H)+ (C26H32N6O6 requires 525.2454). Anal. (C26H32N6O6‚1HCl)
C, H, N.
4-[1-(5-Me t h oxy-1H -b e n zim id a zol-2-yl)p ip e r id in -4-
yla m in o]ben zoic a cid ter t-bu tyl ester (12): 1H NMR
(DMSO) δ 13.40 (br s, 1H), 7.63 (d, 2H, J ) 8.3), 7.29 (d, 1H,
J ) 8.7), 6.91 (s, 1H), 6.83 (d, 1H, J ) 8.4), 6.65 (d, 2H, J )
8.3), 6.50 (s, 1H), 4.13 (d, 2H, J ) 12.7), 3.77 (s, 3H), 3.73 (m,
1H), 3.47 (m, 4H), 2.06 (d, 2H, J ) 11.0), 1.48 (s, 9H); 13C NMR
(DMSO) δ 165.2, 156.1, 151.3, 149.8, 131.0, 130.9, 124.0, 117.8,
111.8, 111.3, 110.2, 96.4, 79.0, 55.7, 47.3, 45.6, 30.2, 30.0;
HRMS (FAB) m/z 423.2388 (M + H)+ (C24H30N4O3 requires
423.2389). Anal. (C24H30N4O3‚1HCl‚1/2H2O) C, H, N.
4-[1-(6,7-Dim eth oxy-4-p-tolyla m in oqu in a zolin -2-yl)p i-
p er id in -4-yla m in o]b en zoic Acid ter t-Bu t yl E st er (16).
Compound QPH (BI2758-159C) (0.099 g, 0.3 mmol) was added
to a solution of 49 (0.10 g, 0.37 mmol) in n-pentanol (5 mL) at
25 °C. The mixture was heated to 120 °C and maintained at
3-Am in o-5-[1-(4-a m in o-6,7-d im eth oxyqu in a zolin -2-yl)-
p ip er id in -4-yla m in o]p yr a zin e-2-ca r boxylic a cid m eth yl
1
ester (2): H NMR (DMSO) δ 7.59 (d, 1H, J ) 7.7), 7.41 (s,
1H), 7.22 (s, 1H), 7.15 (br s, 4H), 6.73 (s, 1H), 4.63 (d, 2H, J )
13.2), 4.10 (m, 1H), 3.82 (s, 3H), 3.77 (s, 3H), 3.69 (s, 3H), 2.99
(t, 2H, J ) 9.8), 1.90 (d, 2H, J ) 10.0), 1.39 (m, 2H); 13C NMR
(DMSO) δ 167.0, 161.1, 158.0, 156.6, 154.7, 154.2, 144.8, 123.0,
109.5, 104.9, 103.7, 102.6, 98.4, 55.8, 55.4, 50.8, 47.1, 42.4, 31.2;
HRMS (FAB) m/z 455.2143 (M + H)+ (C21H26N8O4 requires
455.2155). Anal. (C21H26N8O4‚1/2H2O‚1/2CH3OH) C, H, N.
6-[1-(4-Am in o-6,7-d im eth oxyqu in a zolin -2-yl)p ip er id in -
4-yla m in o]n icot in ic a cid m et h yl est er (3): 1H NMR
(DMSO) δ 12.37 (s, 1H), 8.74 (d, 2H, J ) 6.3), 8.57 (d, 1H, J )
2.2), 7.80 (m, 1H), 7.76 (s, 1H), 7.62 (s, 1H), 7.60 (d, 1H, J )
8.8), 6.56 (d, 1H, J ) 8.9), 4.57 (m, 2H), 4.20 (m, 1H), 3.86 (s,
3H), 3.84 (s, 3H), 3.76 (s, 3H), 3.42 (m, 2H), 2.03 (m, 2H), 1.51
(m, 2H); 13C NMR (DMSO) δ 165.6, 161.3, 160.2, 155.1, 151.0,
150.6, 146.6, 136.8, 136.4, 113.1, 107.9, 105.2, 101.5, 99.3, 56.2,
55.9, 51.2, 46.6, 43.4, 30.9; HRMS (FAB) m/z 439.2083 (M +
H)+ (C22H26N6O4 requires 439.2094). Anal. (C22H26N6O4‚1HCl)
C, H, N.
4-[1-(4-Am in o-6,7-d im eth oxyqu in a zolin -2-yl)p ip er id in -
4-yla m in o]ben zoic a cid m eth yl ester (4): 1H NMR (DMSO)
δ 12.15 (s, 1H), 8.75 (d, 2H), 7.73 (s, 1H), 7.69 (d, 2H, J ) 8.7),
7.51 (s, 1H), 6.66 (d, 2H, J ) 8.4), 6.57 (d, 1H, J ) 7.3), 4.52

SAR of Novel 2-Substituted Quinazolines
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 22 4711
that temperature for 12 h. The reaction mixture was then
cooled to room temperature and the desired product was
filtered and rinsed with acetone to give 0.146 g (85.3%) of the
title compound: TLC (Rf ) 0.40; 5% MeOH/CH2Cl2); 1H NMR
(DMSO) δ 12.41 (br s, 1H), 10.71 (br s, 1H), 8.08 (s, 1H), 7.63
(d, 2H, J ) 8.7), 7.57 (s, 1H), 7.55 (d, 2H, J ) 8.3), 7.24 (d,
2H, J ) 8.3), 6.63 (d, 2H, J ) 8.8), 6.44 (d, 1H, J ) 6.9), 4.41
(d, 2H, J ) 12.9), 3.91 (s, 3H), 3.89 (s, 3H), 3.73 (m, 1H), 3.42
(m, 2H), 2.31 (s, 3H), 2.03 (d, 2H, J ) 10.8), 1.49 (s, 9H), 1.41
(m, 2H); 13C NMR (DMSO) δ 165.2, 157.2, 155.2, 151.3, 150.7,
146.9, 136.6, 134.7, 130.9, 129.0, 124.0, 117.7, 111.2, 104.6,
102.3, 99.3, 79.0, 56.5, 56.1, 47.9, 43.7, 30.8, 28.0, 20.6; HRMS
(FAB) m/z 570.3070 (M + H)+ (C33H39N5O4 requires 570.3080).
Anal. (C33H39N5O4‚1HCl) C, H, N.
4-[1-(4-Am in oqu in a zolin -2-yl)p ip er id in -4-yla m in o]ben -
zoic Acid ter t-Bu tyl Ester (17). Compound QDME (BI3163-
162A) (0.070 g, 0.39 mmol) was added to a solution of 49 (0.13
g, 0.47 mmol) in n-pentanol (5 mL) at 25 °C. The mixture was
heated to 120 °C and was maintained at that temperature for
12 h. The reaction mixture was then cooled to room temper-
ature and concentrated to a brown yellow oily residue.
Purification of the residue by flash column chromatography
(gradient elution 0f5% MeOH in CH2Cl2) provided the title
compound (0.12 g, 73%): TLC (Rf ) 0.33; 5% MeOH/CH2Cl2);
1H NMR (CDCl3) δ 7.83 (d, 2H, J ) 8.7), 7.51 (m, 3H), 7.10 (t,
1H, J ) 6.6), 6.57 (d, 2H, J ) 8.8), 5.35 (br s, 2H), 4.81 (d, 2H,
J ) 13.6), 4.00 (br s, 1H), 3.60 (m, 1H), 3.14 (t, 2H, J ) 14.0),
2.13 (d, 2H, J ) 13.2), 1.57 (s, 9H), 1.47 (m, 2H); 13C NMR
(CDCl3) δ 166.1, 161.6, 158.8, 152.0, 150.4, 133.2, 131.5, 125.9,
121.8, 121.3, 120.3, 111.8, 109.7, 79.9, 50.3, 42.8, 32.3, 28.3.
Anal. (C24H29N5O2‚1/4HCl) C, H, N.
48.1, 43.6, 31.2; HRMS (FAB) m/z 424.2003 (M + H)+
(C22H25N5O4 requires 424.1985). Anal. (C22H25N5O4‚2HCl) C,
H, N.
4-(1-Na p h th a len -2-ylp ip er id in -4-yla m in o)ben zoic a cid
(23): 1H NMR (DMSO) δ 8.31 (s, 1H), 8.06 (m, 5H), 7.70 (d,
2H, J ) 8.7), 7.60 (m, 2H), 6.70 (d, 2H, J ) 8.8), 3.76 (m, 5H),
2.17 (m, 4H); 13C NMR (DMSO) δ 167.4, 151.2, 132.7, 131.2,
129.9, 128.0, 127.8, 127.4, 119.3, 117.4, 111.4, 66.3, 29.0;
HRMS (FAB) m/z 347.1770 (M+H)+ (C22H22N2O2 requires
347.1760). Anal. (C22H22N2O2‚2HCl) C, H, N.
4-[1-(Naph th alen e-2-su lfon yl)piper idin -4-ylam in o]ben -
zoic a cid (24): 1H NMR (DMSO) δ 8.44 (s, 1H), 8.20 (m,1H),
8.09 (m, 1H), 7.72 (m, 4H), 7.57 (d, 2H, J ) 5.7), 6.50 (d, 2H,
J ) 6.8), 3.60 (m, 2H), 3.25 (m, 1H), 2.55 (m, 2H), 1.93 (d, 2H,
J ) 11.9), 1.45 (m, 2H); 13C NMR (DMSO) δ 167.4, 151.3, 134.4,
132.7, 131.9, 131.1, 129.3, 129.0, 128.6, 127.9, 122.9, 111.2,
47.2, 45.0, 30.6; HRMS (FAB) m/z 411.1366 (M + H)+
(C22H22N2O4S requires 411.1379). Anal. (C22H22N2O4S‚1/2HCl‚
1/2H2O) C, H, N.
4-[1-(Naph th alen e-2-car bon yl)piper idin -4-ylam in o]ben -
zoic a cid (25): 1H NMR (DMSO) δ 7.98 (m, 4H), 7.66 (d, 2H,
J ) 8.7), 7.55 (m, 3H), 6.65 (d, 2H, J ) 8.8), 4.41 (m, 2H), 3.67
(m, 1H), 3.15 (m, 2H), 1.95 (m, 2H), 1.40 (m, 2H); 13C NMR
(DMSO) δ 169.0, 167.4, 151.1, 133.6, 133.1, 132.3, 131.1, 128.3,
128.1, 127.7, 127.1, 126.8, 126.1, 124.3, 117.3, 111.6, 48.7, 45.9,
31.2; HRMS (FAB) m/z 375.1693 (M + H)+ (C23H22N2O3
requires 375.1709). Anal. (C23H22N2O3‚11/2HCl‚1/4H2O) C, H,
N.
4-[1-(5-Met h oxy-1H -b en zoim id a zol-2-yl)p ip er id in -4-
yla m in o]ben zoic a cid (27): 1H NMR (DMSO) δ 13.00 (br s,
1H), 7.68 (d, 2H, J ) 8.6), 7.30 (d, 1H, J ) 8.7), 6.92 (d, 1H, J
) 2.2), 6.85 (dd, 1H, J ) 8.0, 2.3), 3.99 (d, 2H, J ) 13.3), 3.78
(s, 3H), 3.70 (m, 1H), 3.46 (t, 2H, J ) 11.2), 2.09 (d, 2H, J )
10.7), 1.56 (m, 2H); 13C NMR (DMSO) δ 167.4, 156.2, 151.3,
150.0, 131.2, 131.0, 124.0, 117.1, 111.9, 111.3, 110.3, 96.6, 55.7,
47.3, 45.4, 30.2; HRMS (FAB) m/z 367.1777 (M + H)+
(C20H22N4O3 requires 367.1765). Anal. (C20H22N4O3‚1CF3COOH‚
3/4H2O) C, H, N.
Gen er a l P r oced u r e for ter t-Bu t yl E st er Clea va ge.
Hydrogen chloride (4 M in 1,4-dioxane) or trifluoroacetic acid
in excess amount was added to the substrate and the reaction
mixture was capped with a drying tube and stirred at 25 °C
for 12 h. The reaction mixture was concentrated to give the
product as either HCl salt or TFA salt.
Gen er a l P r oced u r e for Meth yl Ester Hyd r olysis. An
excess of potassium hydroxide was added to a solution of the
substrate in MeOH/H2O (10%; v/v) at 25 °C. The reaction
mixture was heated to 85 °C for 12 h then cooled to room
temperature. The mixture was concentrated and acidified with
HCl (aq) and the desired product was filtered and rinsed with
cold H2O.
4-[1-(6,7-Dim eth oxy-4-p-tolyla m in oqu in a zolin -2-yl)p i-
p er id in -4-yla m in o]ben zoic a cid (31): 1H NMR (DMSO) δ
12.10 (br s, 1H), 10.56 (br s, 1H), 7.92 (s, 1H), 7.67 (d, 2H, J
) 8.5), 7.51 (d, 2H, J ) 8.3), 7.27 (s, 1H), 7.26 (d, 2H, J ) 7.9),
6.64 (d, 2H, J ) 8.4), 4.32 (d, 2H, J ) 12.6), 3.91 (s, 3H), 3.89
(s, 3H), 3.68 (m, 1H), 3.36 (t, 2H, J ) 10.7), 2.32 (s, 3H), 2.05
(d, 2H, J ) 8.0), 1.47 (m, 2H); 13C NMR (DMSO) δ 167.4, 157.2,
155.4, 151.4, 150.7, 147.0, 136.4, 135.0, 134.6, 131.2, 129.1,
124.0, 117.0, 111.2, 104.3, 102.2, 99.1, 56.3, 56.1, 47.9, 43.5,
30.8, 20.6; HRMS (FAB) m/z 514.2459 (M + H)+ (C29H31N5O4
requires 514.2454). Anal. (C29H31N5O4‚1CF3COOH‚11/4H2O)
C, H, N.
4-[1-(4-Am in oqu in a zolin -2-yl)pip er idin -4-yla m in o]ben -
zoic a cid (32): 1H NMR (DMSO) δ 11.8 (br s, 1H), 9.07 &
8.95 (br s, 2H), 8.20 (d, 1H, J ) 7.8), 7.82 (t, 1H, J ) 7.8), 7.68
(d, 3H, J ) 8.5), 7.42 (t, 1H, J ) 7.4), 6.65 (d, 2H, J ) 8.8),
4.47 (d, 2H, J ) 13.2), 3.73 (m, 1H), 3.42 (t, 2H, J ) 11.3),
2.07 (d, 2H, J ) 10.7), 1.50 (m, 2H); 13C NMR (DMSO) δ 167.4,
162.1, 151.4, 139.8, 135.4, 131.2, 124.6, 120.0, 117.3, 117.0,
111.2, 109.1, 47.8, 43.4, 30.9. Anal. (C20H21N5O2‚11/2CF3-
COOH) C, H, N.
Gen er a l P r oced u r e for Ar om a tic Nu cleop h ilic Su b-
stitu tion Rea ction . Compound 41 or 45 and N,N′-diisopro-
pylethylamine (5.5 equiv) were added sequentially to a solution
of compound 33, 34, or 42 (0.9 equiv) in DMF (3 mL/mmol) at
25 °C. The mixture was stirred at 25 °C for 12 h then was
concentrated and the residue was diluted with a mixture of
H2O/EtOAc (v/v, 50:50). The aqueous layer was extracted with
more EtOAc. The combined organic layer was dried (Na2SO4),
filtered, and concentrated in vacuo to give a dark brown solid
residue. Purification of the residue was effected by flash
column chromatography.
3-Am in o-5-[1-(4-a m in o-6,7-d im eth oxyqu in a zolin -2-yl)-
p ip er id in -4-yla m in o]-6-ch lor op yr a zin e-2-ca r boxylic a cid
(18): 1H NMR (DMSO) δ 12.20 (br s, 1H), 8.50 (br s, 1H), 7.69
(s, 1H), 7.40 & 7.31 (br s, 2H),7.16 (d, 1H, J ) 7.2), 4.70 (d,
2H, J ) 11.5), 4.24 (m, 1H), 3.86 (s, 3H), 3.82 (s, 3H), 3.10 (m,
2H), 1.92 (m, 2H), 1.66 (m, 2H); 13C NMR (DMSO) δ 167.4,
161.3, 155.7, 155.1, 150.6, 146.5, 119.0, 109.2, 104.8, 101.7,
56.2, 55.9, 47.7, 43.9, 30.4; HRMS (FAB) m/z 475.1589 (M +
H)+ (C20H23N8O4Cl requires 475.1604). Anal. (C20H23N8O4Cl‚
2HCl‚1/2H2O) C, H, N.
6-[1-(4-Am in o-6,7-d im eth oxyqu in a zolin -2-yl)p ip er id in -
4-yla m in o]n icotin ic a cid (20): 1H NMR (DMSO) δ 12.36
(br s, 1H), 9.56 (br s, 1H), 8.78 (br s, 2H), 8.36 (s, 1H), 8.07 (d,
1H, J ) 9.2), 7.75 (s, 1H), 7.61 (s, 1H), 7.11 (d, 1H, J ) 9.3),
4.64 (m, 2H), 4.29 (m, 1H), 3.85 (s, 3H), 3.83 (s, 3H), 3.37 (m,
2H), 2.12 (m, 2H), 1.60 (m, 2H); 13C NMR (DMSO) δ 164.7,
161.3, 155.2, 154.4, 151.0, 146.7, 141.8, 140.1, 136.3, 115.2,
112.4, 105.2, 101.6, 99.3, 56.3, 56.0, 48.4, 43.3, 30.4; HRMS
(FAB) m/z 425.1948 (M + H)+ (C21H24N6O4 requires 425.1937).
Anal. (C21H24N6O4‚2HCl‚2H2O) C, H, N.
4-[1-(4-Am in o-6,7-d im eth oxyqu in a zolin -2-yl)p ip er id in -
4-yla m in o]ben zoic a cid (22): 1H NMR (DMSO) δ 12.08 (br
s, 2H), 8.85 (br s, 1H), 8.64 (br s, 1H), 7.73 (s, 1H), 7.67 (d,
2H, J ) 8.7), 7.48 (s, 1H), 6.65 (d, 2H, J ) 8.8), 6.47 (br s,
1H), 4.51 (d, 2H, J ) 13.2), 3.88 (s, 3H), 3.84 (s, 3H), 3.71 (m,
1H), 3.35 (t, 2H, J ) 12.0), 2.06 (d, 2H, J ) 10.4), 1.47 (m,
2H); 13C NMR (DMSO) δ 167.8, 161.6, 155.7, 151.7, 151.1,
147.1, 136.2, 131.6, 117.1, 111.6, 105.0, 101.7, 99.1, 56.5, 56.4,
3-Am in o-5-(1-ter t-bu toxycar bon ylpiper idin -4-ylam in o)-
6-ch lor op yr a zin e-2-ca r boxylic a cid m eth yl ester (35): 1H
NMR (CDCl3) δ 6.50 (br, 2H), 5.46 (d, 1H, J ) 7.4), 4.13 (m,
1H), 4.08 (m, 2H), 3.89 (s, 3H), 2.93 (t, 2H, J ) 11.7), 2.03 (d,

4712 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 22
Kung et al.
2H, J ) 12.0), 1.47 (s, 9H), 1.42 (m, 2H); 13C NMR (CDCl3) δ
166.4, 155.4, 154.5, 150.6, 121.2, 110.5, 79.6, 51.8, 48.3, 42.5,
31.6, 28.3; HRMS (FAB) m/z 408.1429 (M + Na)+ (C16H24N5O4-
Cl requires 408.1415).
3-Am in o-5-(1-b e n zylp ip e r id in -4-yla m in o)-6-ch lor o-
p yr a zin e-2-ca r boxylic a cid m eth yl ester (37): 1H NMR
(CDCl3) δ 7.31 (s, 5H), 5.42 (d, 1H, J ) 7.4), 3.90 (m, 1H), 3.88
(s, 3H), 3.53 (s, 2H), 2.84 (d, 2H, J ) 11.8), 2.17 (t, 2H, J )
11.2), 1.99 (d, 2H, J ) 9.3), 1.60 (m, 2H); 13C NMR (CDCl3) δ
166.5, 155.6, 150.9, 138.4, 128.9, 128.2, 127.0, 121.4, 110.0,
63.0, 52.0, 51.7, 48.2, 31.9; HRMS (FAB) m/z 376.1549 (M)+.
(C18H22N5O2Cl requires 376.1540). Anal. (C18H22N5O2Cl) C, H,
N.
6-(1-Ben zylp ip er id in -4-yla m in o)n icotin ic a cid m eth yl
ester (39): 1H NMR (CDCl3) δ 8.73 (d, 1H, J ) 2.1), 7.95 (m,
1H), 7.30 (m, 5H), 6.32 (d, 1H, J ) 8.8), 5.01 (d, 1H, J ) 7.8),
3.85 (s, 3H), 3.71 (m, 1H), 3.52 (s, 2H), 2.85 (m, 2H), 2.18 (m,
2H), 1.20 (m, 2H), 1.57 (m, 2H); 13C NMR (CDCl3) δ 166.4,
160.1, 151.6, 138.3, 129.0, 128.1, 127.6, 127.0, 115.0, 105.8,
63.0, 52.0, 51.4, 48.4, 32.3; HRMS (FAB) m/z 326.1879 (M +
H)+ (C19H23N3O2 requires 326.1869).
4-(4-ter t-Bu toxyca r bon yl-2-n itr op h en yla m in o)p ip er i-
d in e-1-ca r boxylic a cid ter t-bu tyl ester (43): 1H NMR
(CDCl3) δ 8.81 (s, 1H), 8.36 (d, 1H, J ) 7.3), 8.02 (d, 1H, J )
8.3), 6.88 (d, 1H, J ) 9.3), 4.05 (d, 2H, J ) 13.3), 3.73 (m, 1H),
3.06 (t, 2H, J ) 11.2), 2.07 (d, 2H, J ) 11.1), 1.59 (s, 9H), 1.45
(s, 9H); 13C NMR (CDCl3) δ 164.2, 154.6, 146.3, 136.4, 131.3,
129.5, 119.3, 113.4, 81.4, 80.0, 49.6, 42.0, 31.6, 28.4, 28.2;
HRMS (FAB) m/z 422.2304 (M + H)+ (C21H31N3O6 requires
422.2291).
4-(1-Ben zylp ip er id in -4-yla m in o)ben zoic Acid Meth yl
Ester (46). 4-Bromomethylbenzoate (4.3 g, 20 mmol) was
dissolved in 40 mL of anhydrous toluene. 4-Amino-1-benzyl
piperidine (4.8 mL, 22 mmol), tris(dibenzylideneacetone)-
dipalladium(0) (60 mg, 0.07 mmol), (()-2,2′-bis(diphenylphos-
phino)-1,1′-binaphthyl [(()-BINAP] (124 mg, 0.2 mmol), and
cesium carbonate (9.2 g, 28 mmol) were added sequentially at
25 °C. The resulting mixture was stirred and heated to 80 °C,
maintained at that temperature for 12 h, and then cooled to
25 °C. The reaction mixture was diluted with a mixture of
MeOH/CH2Cl2 (150 mL, v/v, 50:50). The diluted mixture was
filtered through Celite and the filtrate was concentrated under
reduced pressure. The resulting residue was partitioned
between EtOAc (200 mL) and H2O (200 mL). The organic layer
was dried (Na2SO4), filtered, and concentrated in vacuo to give
a deep yellow solid residue. Purification of the residue by flash
column chromatography (gradient elution 30f40% EtOAc in
hexanes) provided the title compound as a pale yellow solid
residue (2.26 g, 35%): TLC (Rf ) 0.40; 60% EtOAc/hexanes);
1H NMR (CDCl3) δ 7.84 (d, 2H, J ) 8.8), 7.31 (s, 5H), 6.52 (d,
2H, J ) 8.9), 4.04 (d, 1H, J ) 7.8), 3.84 (s, 3H), 3.53 (s, 2H),
3.40 (m, 1H), 2.85 (d, 2H, J ) 11.9), 2.16 (t, 2H, J ) 12.7),
1.99 (m, 2H), 1.52 (m, 2H); 13C NMR (CDCl3) δ 167.3, 150.9,
138.2, 131.6, 129.1, 128.2, 127.1, 118.0, 111.7, 63.1, 52.1, 51.5,
49.5, 32.3. Anal. (C20H24N2O2) C, H, N.
) 8.7), 7.31 (s, 5H), 6.51 (d, 2H, J ) 8.8), 3.90 (m, 1H), 3.52 (s,
2H), 2.85 (d, 2H, J ) 12.1), 2.15 (t, 2H, J ) 11.5), 1.99 (m,
2H), 1.56 (s, 9H), 1.47 (m, 2H); 13C NMR (CDCl3) δ 166.1, 150.5,
138.3, 131.4, 129.1, 128.2, 127.1, 120.1, 111.6, 79.8, 63.1, 52.2,
49.6, 32.3, 28.3. Anal. (C23H30N2O2‚1/2 H2O) C, H, N.
4-(P ip er id in -4-yla m in o)ben zoic Acid ter t-Bu tyl Ester
(49). Ammonium formate (4.2 g, 66 mmol) was added to a
solution of 48 (2.7 g, 7.3 mmol) in 120 mL of absolute ethanol.
The mixture was purged with argon; then palladium (1 g, 5%
on activated carbon) was added. The resulting mixture was
heated to 80 °C and maintained at that temperature for 12 h.
After cooling to 25 °C, the mixture was filtered through Celite
and the filtrate was concentrated in vacuo. The residue was
cooled to 0 °C, saturated Na2CO3 (100 mL) was added, and
the resulting mixture was stirred for 30 min. The aqueous
layer was extracted with EtOAc (3 × 100 mL). The combined
organic layers were dried (Na2SO4), filtered, and concentrated
in vacuo to give 1.85 g (92%) of the title compound: TLC (Rf
) 0.20; 10% MeOH/CH2Cl2); 1H NMR (CDCl3) δ 7.80 (d, 2H, J
) 8.7), 6.53 (d, 2H, J ) 8.8), 4.10 (m, 1H), 3.40 (m, 1H), 3.11
(d, 2H, J ) 12.7), 2.70 (t, 2H, J ) 11.9), 2.04 (m, 2H), 1.79 (s,
1H), 1.56 (s, 9H), 1.35 (m, 2H); 13C NMR (CDCl3) δ 166.0, 150.3,
131.2, 119.9, 111.5, 79.6, 49.9, 45.3, 33.5, 28.2. Anal. (C16H24
-
N2O2‚1/4H2O) C, H, N.
4-(1-Na p h th a len -2-ylp ip er id in -4-yla m in o)ben zoic Acid
ter t-Bu tyl Ester (8). Sodium tert-butoxide (0.4 g, 4 mmol) was
added to a solution of 2-bromonaphthalene (0.3 g, 1.48 mmol)
and 49 (0.4 g, 1.48 mmol) in 5 mL of anhydrous toluene at 25
°C. Tris(dibenzylideneacetone)dipalladium(0) (6 mg, 0.007
mmol) and (()-BINAP (12.4 mg, 0.02 mmol) were added
sequentially. The reaction mixture was heated to 80 °C,
maintained at that temperature for 12 h, then was cooled to
25 °C, and diluted with a mixture of CH3OH/CH2Cl2 (150 mL,
v/v, 50:50). The diluted mixture was filtered through Celite
and the filtrate was concentrated in vacuo. The resulting
residue was partitioned between CH2Cl2 (150 mL) and H2O
(150 mL). The organic layer was dried (Na2SO4), filtered, and
concentrated in vacuo to give a deep yellow solid residue.
Purification of the residue by flash column chromatography
(gradient elution 0f25% EtOAc in hexanes) provided the title
compound (0.35 g, 59%): TLC (Rf ) 0.80; 40% EtOAc/hexanes);
1H NMR (CDCl3) δ 7.83 (d, 2H, J ) 8.4), 7.70 (m, 3H), 7.32
(m, 3H), 7.15 (d, 1H, J ) 2.1), 6.56 (d, 2H, J ) 8.7), 4.02 (d,
1H, J ) 7.8), 3.76 (d, 2H, J ) 12.7), 3.54 (m, 1H), 2.98 (t, 2H,
J ) 12.0), 2.20 (d, 2H, J ) 10.7), 1.67 (m, 2H), 1.57 (s, 9H);
13C NMR (CDCl3) δ 166.0, 150.4, 149.1, 134.7, 131.5, 128.7,
128.5, 127.4, 126.7, 126.3, 123.4, 120.6, 119.8, 111.9, 110.7,
79.8, 49.6, 48.8, 32.1, 28.4; HRMS (FAB) m/z 402.2321 (M)+.
(C26H30N2O2 requires 402.2307).
In Vitr o An tiba cter ia l Activity. 1. Ba cter ia l Str a in s.
Streptococcus pyogenes, Klebsiella pneumoniae, Escherichia
coli, Staphylococcus aureus, and Enterococcus faecalis used in
the antibacterial activity studies (ATCC 14289, 49399, 13883,
25922, 13709, and 29212, respectively) were obtained from the
American Type Culture Collection, Rockville, MD. E. coli imp-
is a mutant strain of wild-type E. coli with increased outer
membrane permeability and was a gift of Spenser Benson
(University of Maryland at College Park).17 In initial screens,
E. coli imp- and S. pyrogenes (ATCC 14289) were used. The
E. coli imp- strain was grown in LB broth, and the S. pyogenes
strain was grown in Todd-Hewitt broth. Interesting com-
pounds were further evaluated in screens against other
bacterial strains. S. aureus was grown in trypticase soy broth,
E. faecalis in Todd-Hewitt broth, and wild-type E. coli and
K. pneumoniae in nutrient broth. All bacteria were grown at
37 °C.
4-(1-Ben zylp ip er id in -4-yla m in o)ben zoic Acid ter t-Bu -
tyl Ester (48). Sodium tert-butoxide (5.6 g, 58 mmol) was
added to a solution of 4-bromomethylbenzoate (4.3 g, 20 mmol)
in 40 mL of anhydrous toluene at 25 °C. The resulting mixture
was heated to 80 °C and stirred for 15 min. 4-Amino-1-
benzylpiperidine (4.8 mL, 22 mmol), tris(dibenzylidene-
acetone)dipalladium(0) (60 mg, 0.07 mmol), and (()-BINAP
(124 mg, 0.2 mmol) were added sequentially. The reaction
mixture was maintained at 80 °C for 12 h, then cooled to 25
°C, and diluted with a mixture of MeOH/CH2Cl2 (150 mL, v/v,
50:50). The diluted mixture was filtered through Celite and
the filtrate was concentrated under reduced pressure. The
resulting residue was partitioned between CH2Cl2 (150 mL)
and H2O (150 mL). The organic layer was dried (Na2SO4),
filtered, and concentrated in vacuo to give a deep yellow solid
residue. This residue was stirred for 30 min with a mixture of
EtOAc/hexanes (100 mL, 30/70, v/v) and the desired product
was filtered as a yellowish powder (3.57 g, 49%): TLC (Rf )
2. Deter m in a tion of Min im u m In h ibitor y Con cen tr a -
tion s (MICs). Assays were carried out in 150 µL volume in
duplicate in 96-well clear flat-bottom plates. The bacterial
suspension from an overnight culture growth in appropriate
medium was added to a solution of test compound in 4% DMSO
in water. Final bacterial inoculum was approximately 105-
106 CFU (colony forming units)/well. The percent growth of
the bacteria in test wells relative to that observed for a well
1
0.51; 50% EtOAc/hexanes); H NMR (CDCl3) δ 7.79 (d, 2H, J

SAR of Novel 2-Substituted Quinazolines
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containing no compound was determined by measuring ab-
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Ack n ow led gm en t. We are grateful for many helpful
discussions throughout the course of this work with
Prof. Michael E. J ung. We also thank Dr. Karl D.
Hargrave of Boehringer Ingelheim for providing com-
pounds QPH and QDME. This work was supported by
a grant from the Defense Advanced Research Projects
Agency.
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