Antimicrobial activity of various 4- and 5-substituted 1-phenylnaphthalenes

Article abstract of DOI:10.1016/j.ejmech.2012.12.027

Bacterial cell division occurs in conjunction with the formation of a cytokinetic Z-ring structure comprised of FtsZ subunits. Agents that can disrupt Z-ring formation have the potential, through this unique mechanism, to be effective against several of the newly emerging multi-drug resistant strains of infectious bacteria. 1- and 12-Aryl substituted benzo[c]phenanthridines have been identified as antibacterial agents that could exert their activity by disruption of Z-ring formation. Substituted 4- and 5-amino-1-phenylnaphthalenes represent substructures within the pharmacophore of these benzo[c] phenanthridines. Several 4- and 5-substituted 1-phenylnaphthalenes were synthesized and evaluated for antibacterial activity against Staphylococcus aureus and Enterococcus faecalis. The impact of select compounds on the polymerization dynamics of S. aureus FtsZ was also assessed.

Full text of DOI:10.1016/j.ejmech.2012.12.027

European Journal of Medicinal Chemistry 60 (2013) 395e409
Contents lists available at SciVerse ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Antimicrobial activity of various 4- and 5-substituted
1-phenylnaphthalenes
,
Cody Kelleya, Songfeng Lu b, Ajit Parhi b, Malvika Kaul c, Daniel S. Pilch c, Edmond J. LaVoie a
*
a Department of Medicinal Chemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8020, USA
b TAXIS Pharmaceuticals Inc., North Brunswick, NJ, 08902, USA
c Department of Pharmacology, The University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Bacterial cell division occurs in conjunction with the formation of a cytokinetic Z-ring structure
comprised of FtsZ subunits. Agents that can disrupt Z-ring formation have the potential, through
this unique mechanism, to be effective against several of the newly emerging multi-drug resistant strains
of infectious bacteria. 1- and 12-Aryl substituted benzo[c]phenanthridines have been identified as
antibacterial agents that could exert their activity by disruption of Z-ring formation. Substituted 4- and
5-amino-1-phenylnaphthalenes represent substructures within the pharmacophore of these benzo[c]
phenanthridines. Several 4- and 5-substituted 1-phenylnaphthalenes were synthesized and evaluated
for antibacterial activity against Staphylococcus aureus and Enterococcus faecalis. The impact of select
compounds on the polymerization dynamics of S. aureus FtsZ was also assessed.
Received 15 August 2012
Received in revised form
10 December 2012
Accepted 11 December 2012
Available online 20 December 2012
Keywords:
Antibacterial
1-Phenylnaphthalenes
FtsZ-targeting
Ó 2012 Elsevier Masson SAS. All rights reserved.
Enterococcus faecalis
Staphylococcus aureus
1. Introduction
that chelerythrine (b) has similar effects on S. aureus and Bacillus
subtilis. In addition, the presence of hydrophobic functionality at
Nosocomial infections associated with multi-drug resistant
pathogens such as methicillin-resistant Staphylococcus aureus
(MRSA) and vancomycin-resistant enterococci (VRE) represent
a major health concern. Bacterial resistance to conventional anti-
biotics has created a critical need for the identification of novel
therapeutic antibacterial targets [1,2]. FtsZ is an essential and
highly conserved bacterial protein involved in cytokinesis [3e8].
Cell division in bacteria occurs at the site of formation of a cytoki-
netic Z-ring polymeric structure comprised of FtsZ subunits [3].
Several recent reviews have discussed the potential of antibacterial
agents that target FtsZ, as well as recent advances in the discovery
of small molecules that perturb processes in which FtsZ is involved
[9e13]. FtsZ-targeting antibacterial agents can exert their disrup-
tive effects on the Z-ring by either enhancing or inhibiting FtsZ
self-polymerization [14e21].
either the 12-or 1-positionof benzo[c]phenanthridines, as inthe case
of (c) and (d), significantly enhanced antibacterial activity relative to
either (a) or (b) [22,23]. These compounds (aed) have a constitutive
cationic charge that can adversely affect their desired pharmacoki-
netic properties. 4- and 5-Substituted 1-phenylnaphthalenes repre-
sent a truncated form within the core structure of these alkaloids.
Similar results were observed within a series of substituted dibenzo
[a,g]quinolizinium derivatives [24]. In the present study, we exam-
ined the relative structureeactivity relationships associated with
the potential antibacterial activity of several 4- and 5-substituted
1-phenylnaphthalene derivatives (Fig. 1). Unlike sanguinarine and
chelerythrine, the 4- and 5-substituted 1-phenylnaphthalene deriv-
atives selected for synthesis and evaluation did not possess a consti-
tutive cationic charge. Instead, theycontained functionalityat the site
inproximitytothatof theiminium cationofcompounds (aed), which
would to some extent be protonated at physiological pH. Using ami-
nomethyl, alkylamidinomethyl, oralkyl guanidinomethyl derivatives,
the functionality of different base strengths was assessed. Increasing
the alkyl linkage to two carbons from the naphthyl-ring further
increases basic properties and the degree to which these derivatives
will be protonated under physiological conditions.
Sanguinarine (a) (Fig.1) is a plant alkaloid that has been identified
as a small molecule that alters FtsZ Z-ring formation and has modest
antibacterial activity [15]. Studies in our laboratory have also shown
* Corresponding author. Tel.: þ1 848 445 2674; fax: þ1 732 445 6312.
E-mail address: elavoie@pharmacy.rutgers.edu (E.J. LaVoie).
0223-5234/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.ejmech.2012.12.027

396
C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
O
O
OCH3
OCH3
N
N
O
CH3
O
CH3
O
O
(a)
(b)
OCH3
OCH3
OCH3
OCH3
N
N
H3CO
CH3
H3CO
Cl
CH3
Cl
OCH3
OCH3
(d)
(c)
Y
X
5-Substituted 1-Phenylnaphthalene
4-Substituted 1-Phenylnaphthalene
Fig. 1. The structure of sanguinarine (a), chelerythrine (b), 2,3,7,8-tetramethoxy-5-methyl-12-phenylbenzo[c]phenathridin-5-ium chloride (c), and 2,3,7,8-tetramethoxy-5-methyl-
1-phenylbenzo[c]phenathridin-5-ium chloride (d).
2. Chemistry
Table 1
4- and 5-substituted 1-phenylnaphthalenes.
The methods used for preparation of the 4-substituted-1-
phenylnaphthalenes listed in Table 1 are outlined in Scheme 1.
Treatment of 4-hydroxy-1-naphthaldehyde with triflic anhydride
followed by Suzuki coupling with 4-(t-butyl)phenylboronic acid
provided 4-(4-(t-butyl)phenyl)-1-naphthaldehyde. This interme-
diate was reduced with NaBH4 to its hydroxymethyl derivative,
which was converted to its azidomethyl derivative allowing for
reduction with PPh3 to give 1. Alternatively, this benzyl alcohol
intermediate was treated under Mitsunobu conditions to provide
the bis-N-Boc protected guanidinomethyl intermediate, which was
treated with trifluoroacetic acid to yield 3. Condensation of 4-(4-(t-
butyl)phenyl)-1-naphthaldehyde with nitromethane provided the
X
Y
R1
R2
2-nitroethylene intermediate, which was reduced with LAH to give
2. Treatment of with 1,3-di-Boc-2-(trifluoromethylsulfonyl)
1
2
3
4
5
6
7
8
CH2NH2
CH2CH2NH2
CH2NC(NH2)2
CH2CH2NC(NH2)2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
t-butyl
t-butyl
t-butyl
t-butyl
t-butyl
t-butyl
t-butyl
t-butyl
t-butyl
cyclopropyl
Cl
Br
CF3
CF3
CF3
CF3
CF3
CF3
CF3
2
guanidine followed by treatment with TFA provided the
2-guanidinoethyl derivative, 4.
The 5-substituted-1-phenylnaphthalenes listed in Table 1 were
synthesized as outlined in Schemes 2e4. 1-Naphthaldehyde was
converted to 5-bromo-1-naphthaldehyde as previously described
[25]. 5-Bromo-1-naphthaldehyde was subjected to a Suzuki coupling
reaction to form the appropriate 5-phenyl-1-naphthaldehyde,
which was then reduced to its hydroxymethyl derivative with
NaBH4. These 5-phenyl-1-hydroxymethylnaphthalenes were then
treated under Mitsunobu conditions with 1,3-bis(t-butoxycarbonyl)
guanidine followed by treatment with TFA to provide the guanidi-
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
CH2NH2
CH2CH2NH2
CH2CNH(NH2)
CH2NC(NH2)2
CH2CH2NC(NH2)2
CH2NC(NH2)2
CH2NC(NH2)2
CH2NC(NH2)2
CH2CNH(NH2)
CH2NC(NH2)2
CH2CH2NC(NH2)2
CH2CH2NH2
CH2CH2NH2
CH2NC(NH2)2
CH2CH2NC(NH2)2
9
10
11
12
13
14
15
16
17
18
19
nomethyl derivatives,
8
and 14. Alternatively, 5-bromo-1-
OCH3
OH
OCH3
OCH3
hydroxymethylnaphthalene was converted first to its bis-(N-Boc)
guanidinomethyl derivative and subsequently subjected to a Suzuki
coupling followed by treatment with TFA to provide the

C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
397
OH
d,e
a, b
c
NH2
CHO
CHO
OH
1
j,i
f,g
h,i
N
N
NH2
NH2
H2N
NH2
NH2
4
2
3
Scheme 1. Preparation of 1-(4-t-butylphenyl)-4-naphthalene derivatives. Reagents and conditions: (a) Tf2O, Et3N, DCM, ꢀ78 ꢁC; (b) 4-t-butylphenylboronic acid, Pd(OAc)2, XPhos,
K2CO3, ACN/H2O, 90 ꢁC; (c) NaBH4, EtOH, rt; (d) DPPA, DBU, THF, 0 ꢁC to rt; (e) PPh3 polymer bound, THF/H2O, rt; (f) CH3NO2, NH4OAc, reflux; (g) LAH, THF, rt; (h) 1,3-di-Boc-2-
(trifluoromethylsulfonyl)guanidine, Et3N, CH2Cl2, rt; (i) TFA, CH2Cl2, 0 ꢁC to rt; (j) 1,3-bis(t-butoxycarbonyl)guanidine, PPh3, DIAD, toluene, 0 ꢁC to rt.
1-guanidinomethyl-5-phenyl substituted naphthalene, 18. In
the case of 5-(4-t-butylphenyl)-1-hydroxymethylnaphthalene,
formation of its mesylate followed by treatment with sodium
azide and reduction with triphenylphosphine provided the
1-aminomethyl derivative, 5.
The 5-[(4-trifluoromethyl)phenyl]- and 5-[(4-t-butyl)phenyl]-
1-amidinomethylnaphthalenes, 7 and 13, were synthesized from
their respective bromomethylnaphthalenes, which were synthe-
sized by treatment of their 1-hydroxymethylnaphthalene deriva-
tives with PBr3.
3. Results and discussion
3.1. In vitro antibacterial activity
The antibiotic activities of several 4- and 5-substituted
1-phenylnaphthalenes are provided in Table 2.
The data in Table 2 include the relative activities of (4-t-butyl)
phenylnaphthalenes with identical substituents at either the 4- or
5-position (1e9). Among the pairs of similarly substituted deriva-
tives are the aminomethyl derivatives, 1 and 5; 2-aminoethyl
derivatives, 2 and 6; guanidinomethyl derivatives, 3 and 8 and;
2-guanidinoethyl derivatives, 4 and 9. The only notable difference
in activity is that the 5-substituted guanidinoalkyl derivatives,
8 and 9, tend to be slightly more active than their comparable
4-substituted isomers, 3 and 4, in S. aureus. The data suggest that, at
either the 4- or 5-position, the more basic guanidine derivatives
(3, 8 and 4, 9) have a tendency to be more potent than their cor-
responding aminomethyl (1, 5) and 2-aminoethyl (2, 6) derivatives.
While less active than the 5-guanidinomethyl derivative, 8, the
5-amidinomethyl derivative, 7, exhibited antibacterial activity
comparable to 5 and 6.
The 1-(2-aminoethyl)-5-phenylnaphthalenes,
6
and 16,
were prepared as outlined in Scheme 3. In one instance, the
1-naphthaldehyde intermediates could be condensed with
nitromethane and then reduced with LAH. Alternatively, the
1-hydroxymethyl intermediates could be converted to their
mesylates, reacted with NaCN and then reduced with LAH.
Treatment of the requisite 2-aminoethyl derivative with 1,3-di-
Boc-2-(trifluoromethylsulfonyl)guanidine followed by TFA
provided the 2-guanidinoethyl derivatives, 9, 15 and 19.
Preparation of 10 was accomplished by coupling 5-(4-
bromophenyl)-1-naphthaldehyde with cyclopropylboronic acid,
yielding an aldehyde that was reduced to its hydroxymethyl
derivative, which was converted to the bis-(N-Boc)guanidino-
methyl derivative and then treated with TFA. The preparation of 11
and 12 was accomplished by conversion of 5-bromo-1-
naphthaldehyde to its borane ester, which was Suzuki-coupled
Compound 8 was most active against MSSA of the 1-(4-t-
butylphenyl)naphthalenes (1e9),with an MIC of 0.5
mg/mL.
Compounds 1e9 are significantly less active against MRSA, VSE and
VRE. These data prompted further assessment of various 1-phenyl-
5-guanidinomethylnaphthalene derivatives wherein the phenyl
moiety had in place of the p-(t-butyl) substituent a cyclopropyl (10),
chloro (11), bromo (12), or trifluoromethyl group (14e19).
5-Amidinomethyl-1-(4-trifluoromethyl)phenylnaphthalene (13) is
8-fold less active against MSSA and 4-fold less active against
with
either
1-bromo-4-chlorobenzene
or
1-bromo-4-
iodobenzene. The resulting 5-(4-chlorophenyl)-1-naphthaldehyde
and 5-(4-bromophenyl)-1-naphthaldehyde were reduced to their
hydroxymethyl derivatives, treated under Mitsunobu conditions
and subsequently treated with TFA.
MRSA
than
8.
5-(2-Guanidinoethyl)-1-(4-trifluoromethyl)

398
C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
R1
R1
Br
Br
c, d
a, b
8, R1 = t-butyl
14, R1 = CF3
CHO
b, c
OH
N
H2N
NH2
e, f
R1
h, i
N
BocHN
a, d
NHBoc
CF3
CN
g
NH2
R1
5
OCH3
NH2
NH
N
7, R1 = t-butyl
13, R1 = CF3
H2N
NH2
18
Scheme 2. Methods used in the preparation of 5-substituted 1-(4-t-butylphenyl)naphthalenes, 5, 7, and 8, and 1-(4-trifluoromethylphenyl)naphthalene derivatives, 13, 14, and 18.
Reagents and conditions: (a) R1R2-phenylboronic acid, Pd(OAc)2, XPhos, K2CO3, ACN/H2O, 90 ꢁC; (b) NaBH4, EtOH, rt; (c) 1,3-bis(t-butoxycarbonyl)guanidine, PPh3, DIAD, toluene,
0
ꢁC to rt; (d) TFA/CH2Cl2, 0 ꢁC to rt; (e) PBr3, CH2Cl2, 0 ꢁC to rt; (f) KCN, DMF, rt; (g) (i) 4 N HCl/dioxane, Et2O, MeOH, 0 ꢁC; (ii) NH4Cl, EtOH, 85 ꢁC [26]; (h) NaN3, PPh3, DMF/CCl4,
90 ꢁC; (i) polymer-bound PPh3, THF/H2O, rt.
phenylnaphthalene (15) had comparable activity to 9 against MSSA,
but is less active against MRSA, VSE and VRE. The addition of an
o-methoxyl group to the 1-phenyl substituent did slightly improve
the activity of 18 relative to 14 against Enterococcus faecalis, but
slightly decreased the potency of 19 relative to 15 against S. aureus.
As anticipated from the previous structureeactivity studies, the
5-(2-aminoethyl) derivatives, 16 and 17, are less active than simi-
larly substituted 5-(guanidinoalkyl)-1-(4-trifluoromethyl)phenyl-
naphthalenes (15 and 19).
derivatives (1e9) wherein each instance there is less than a one
well difference in potency between pairs of sensitive and resistant
bacterial strains. The potency of these compounds against resistant
bacteria is clearly evident in a comparison of their activity to that
observed with the five known antibiotics used as control agents in
this study. Compounds 3, 8, and 9 had comparable MICs to van-
comycin against MRSA. Compounds 1e9 all had lower MIC values
(2.0e8.0
mg/mL) against VRE than the clinical antibiotics evaluated
in this study.
All of these compounds were more active than chelerythrine
against both E. faecalis strains and only in the case of the
vancomycin-sensitive E. faecalis did one compound, 17, exhibit less
active antibacterial activity than sanguinarine. Several of these
compounds (8e10, and 15) were more active against methicillin-
sensitive S. aureus than either sanguinarine or chelerythrine.
When evaluated for their antibacterial activity against methicillin-
resistant S. aureus, the more potent 1-phenylnaphthalene deriva-
tives had comparable or slightly reduced potency relative to
sanguinarine.
3.2. FtsZ polymerization assays
The selectionof various 4- and 5-susbtituted 1-phenylnaphthalenes
evaluated in this study was based upon the reported activity of
sanguinarine to alter FtsZ Z-ring formation, as well as the observation
that chelerythrine has a similar effect in S. aureus and B. subtilis [15,22].
It has been speculated that agents that alter or perturb the formation of
FtsZ Z-ring could be effective against bacteria that have shown multi-
drug resistance, such as MRSA and VRE [6e9]. Recent studies have
shown that agents that stimulate FtsZ polymerization can cause an
inhibition of FtsZ Z-ring formation [14,17,18]. To determine whether
this mechanism of antibacterial activity may be associated with the
antibacterial activity observed for these 4- and 5-substituted
The various 4- and 5-susbtituted 1-phenylnaphthalenes did not
exhibit pronounce cross-resistance between MSSA and MRSA, as
well as between VSE and VRE, strains of bacteria. This is particularly
apparent among the various 1-(t-butylphenyl)naphthalene

C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
399
R1
R1
R1
R2
R2
R2
Br
c, d, e
a, b
f, g
CHO
i
OH
NH2
N
NH2
NH2
6, R1 = t-butyl; R2 = H
16, R1 = CF3; R2 = OCH3
h
17, R1 = CF3; R2 = OH
9, R1 = t-butyl, R2 = H
19, R1 = CF3, R2 = OCH3
CF3
CF3
CF3
j, e
f, g
N
NH2
NH2
CHO
NH2
15
Scheme 3. Methods used in the preparation of 5-substituted 1-(4-t-butylphenyl)naphthalenes, 6 and 9, and 1-(4-trifluoromethylphenyl)naphthalene derivatives, 15e17 and 19.
Reagents and conditions: (a) R1R2-phenylboronic acid, Pd(OAc)2, XPhos, K2CO3, ACN/H2O, 90 ꢁC; (b) NaBH4, EtOH, rt; (c) MsCl, Et3N, CH2Cl2, 0 ꢁC to rt; (d) KCN, DMF, rt; (e) LAH,
ether; (f) 1,3-di-Boc-2-(trifluoromethylsulfonyl)-guanidine, Et3N, CH2Cl2, rt; (g) TFA/CH2Cl2; (h) BBr3, CH2Cl2, 0 ꢁC to rt; (i) 4-trifluoromethylphenylboronic acid, Pd(OAc)2, XPhos,
K2CO3, ACN/H2O, 90 ꢁC; (j) nitromethane, NH4OAc, 100 ꢁC.
R1
Br
c, d
a, b
e, f
CHO
d
CHO
OH
N
H2N
NH2
10
R1
R1
e, f
11, R1 = Cl
12, R1 = Br
N
OH
H2N
NH2
Scheme 4. Methods used in the preparation of 5-substituted 1-phenylnaphthalenes, 10e12. Reagents and conditions: (a) borane ester, Pd(OAc)2, KOAc, DMF, 80 ꢁC; (b) 4-bromo-X-
benzene [X ¼ Cl or I], Pd(PPh3)4, K2CO, dioxane/H2O, 100 ꢁC; (c) cyclopropylboronic acid, Pd(OAc)2, Pcy3, K3PO4, toluene/H2O, 100 ꢁC; (d) NaBH4, EtOH, rt; (e) 1,3-bis(t-butox-
ycarbonyl)guanidine, PPh3, DIAD, toluene, 0 ꢁC to rt; (f) TFA/CH2Cl2, 0 ꢁC to rt.

400
C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
Table 2
1-phenylnaphthalenes, we examined the effects of select compounds
on the dynamics of FtsZ self-polymerization. To this end, we used
a turbidity assay to monitor the self-polymerization of purified
S. aureus FtsZ (SaFtsZ). In this assay, FtsZ polymerization is detected in
solutionbya time-dependentincreasein solution turbidity, as reflected
by a corresponding increase in solution absorbance at 340 nm (A340).
As illustrative examples, Fig. 2 shows the time-dependent A340
profiles of SaFtsZ in the absence and presence of 6, 8, or the non-
FtsZ-targeting control antibiotic vancomycin at a concentration of
Antistaphylococcal and antienterococcal activities of 4- and 5-substituted
1-phenylnaphthalenes.
Compound
aMIC (
mg/mL)
S. aureus
8325-4
(MSSA)
S. aureus
ATCC 33591
(MRSA)
E. faecalis
ATCC 19433
(VSE)
E. faecalis
ATCC 51575
(VRE)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
4.0
4.0
2.0
2.0
4.0
2.0
4.0
0.5
1.0
1.0
2.0
2.0
4.0
2.0
1.0
8.0
8.0
2.0
2.0
2.0
4.0
0.06
1.0
0.13
0.06
0.03
8.0
4.0
2.0
4.0
4.0
4.0
4.0
2.0
2.0
8.0
8.0
8.0
8.0
8.0
4.0
16
8.0
4.0
2.0
2.0
8.0
2.0
4.0
2.0
2.0
8.0
8.0
8.0
4.0
8.0
4.0
8.0
16
4.0
4.0
8.0
32
8.0
1.0
1.0
0.5
2.0
8.0
4.0
2.0
4.0
8.0
4.0
8.0
4.0
2.0
8.0
8.0
8.0
8.0
16
4.0
8
16
4.0
4.0
16
40 mg/mL. As expected, vancomycin exerts a negligible impact on
SaFtsZ polymerization since its antibacterial target is the bacterial
cell wall. In striking contrast to vancomycin, compounds 6 and
8 markedly increase both the kinetics and extent of SaFtsZ poly-
merization. Stimulation of FtsZ polymerization has been shown to
be the antibacterial mechanism of action for agents such as the
substituted benzamide class of compounds (e.g., PC190723)
[14,17,18]. Our polymerization results suggest that the antibacterial
activity of the phenylnaphthalenes is associated with the stimula-
tory impact of the compounds on the dynamics of FtsZ
polymerization.
17
18
19
16
8.0
8.0
2.0
4.0
>64
2.0
>64
64
4. Conclusions
Sanguinarine
Chelerythrine
Oxacillin
Vancomycin
Erythromycin
Tetracycline
Clindamycin
The antistaphylococcal activities of several 4- and 5-substituted
1-phenylnaphthalenes, as measured by their MIC values, are
significant. Particularly noteworthy are the antibacterial activities
observed against methicillin-resistant S. aureus, which in several
32
>64
>64
>64
>64
>64
instances ranged between 2.0 and 4.0
mg/mL. These values are
>64
comparable to that observed with vancomycin and are well below
the MICs observed with several clinical antibiotics evaluated in this
study. Similar activity against MRSA was observed for sanguinarine
or chelerythrine. As these alkaloids have a constitutive cationic
charge, the physico-chemical properties of several of these
1-phenylnaphthalenes, would be expected to favor their in vivo
absorption and distribution. In addition, the relative MIC values for
several of these 1-phenylnaphthalenes against vancomycin-
resistant E. faecalis (VRE) are lower than the clinical antibiotics or
the two alkaloids evaluated in this study. Our studies with FtsZ
polymerization suggest that the antibacterial activity of the phe-
nylnaphthalenes is associated with the stimulatory impact of the
compounds on the dynamics of FtsZ polymerization. These data
suggest that compounds that interfere with FtsZ polymerization
may prove to be useful in the development of antibiotics against
multi-drug resistant bacteria.
MIC is defined as the lowest compound concentration at which bacterial growth is
ꢂ90% inhibited.
a
Minimum inhibitory concentration (MIC) assays were conducted in accordance
with Clinical Laboratory Standards Institute (CLSI) guidelines for broth micro-
dilution [27].
1.20
1.00
5. Experimental
0.80
5.1. Chemistry: general methods
Vehicle
6
All reactions, unless otherwise stated, were done under nitrogen
atmosphere. Reaction monitoring and follow-up were done using
aluminum backed Silica G TLC plates (UV254 e Sorbent Technolo-
gies), visualizing with ultraviolet light. Flash column chromatog-
raphy was done on a Combi Flash Rf Teledyne ISCO using hexane,
ethyl acetate, dichloromethane, and methanol. The 1H (400 MHz or
300 MHz) and 13C (100 MHz) NMR spectra were done in CDCl3,
Methanol-d4, and DMSO-d6 and recorded on a Bruker Avance III
(400 MHz) Multinuclear NMR Spectrometer or a Varian Unity
INOVA (300 MHz) NMR Spectrometer. Data is expressed in parts
per million relative to the residual nondeuterated solvent signals,
spin multiplicities are given as s (singlet), d (doublet), dd (doublet
of doublets), t (triplet), dt (doublet of triplets), q (quartet), m
(multiplet), bs (broad singlet), and bt (broad triplet), and coupling
constants (J) are reported in Hertz. Melting points were determined
using Mel-temp II apparatus and are uncorrected. HRMS
8
0.60
Vancomycin
0.40
0
50
100
150
200
250
300
Time (minutes)
Fig. 2. Impact of select phenylnaphthalenes on the polymerization of S. aureus FtsZ
(SaFtsZ), as determined by monitoring time-dependent changes in absorbance at
340 nm (A340). Polymerization profiles of SaFtsZ (10
vehicle (violet) or 40 g/mL of either 6 (black), 8 (red), or the non-FtsZ-targeting
comparator antibiotic vancomycin (green) are depicted.
mM) in the presence of DMSO
m

C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
401
experiments were conducted by Washington University Resource
for Biomedical and Bioorganic Mass Spectrometry Department of
Chemistry. All compounds tested for biological activity were
analyzed for purity using a Shimadzu LC-20AT Prominence chro-
matograph equipped with an SPD-20A UVeVIS detector moni-
toring absorbances at both 254 and 280 nm. Compounds were
0.5 N HCl and extracted with EtOAc. Organic layer was collected,
dried over sodium sulfate, and concentrated. Chromatography
using ISCO max gradient 20% EtOAc/hexane yielded product as
a white solid (78 mg, 76% yield); mp 80e81 ꢁC; 1H NMR (400 MHz)
(CDCl3)
(m, 1H), 7.58e7.50 (m, 4H), 7.49e7.44 (m, 3H), 4.85 (s, 2H), 1.46 (s,
9H); 13C NMR (100 MHz) (CDCl3)
150.4, 141.7, 137.4, 132.3, 131.7,
d
8.13 (d, J ¼ 8.0 Hz, 1H), 8.06 (d, J ¼ 8.0 Hz, 1H), 7.65e7.61
analyzed using a PrincetonSPHER-100 5
mM C18 reverse-phase
d
column (150 mm ꢃ 4.6 mm), using gradients of 0.1% TFA in water
with increasing percentages of 0.1% TFA in acetonitrile. Under these
solvent conditions, compounds eluted within 12 min using a flow
rate of 1.0 mL/min and a gradient from 10 to 100% of acetonitrile
containing 0.1% TFA.
130.2, 129.7, 127.3, 127.0, 126.6, 126.2, 126.1, 125.3, 123.7, 53.3,
34.7, 31.5.
5.2.5. (4-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanamine (1)
1-(Azidomethyl)-4-(4-(t-butyl)phenyl)naphthalene (70 mg,
0.222 mmol) was combined in a flask with polymer supported
(3 mmol/g loading) PPh3 (111 mg, 0.333 mmol), THF (5 mL), and
H2O (0.5 mL). Reaction was stirred overnight at RT. Resin was then
filtered off and filtrate concentrated. Chromatography using ISCO
max gradient 10% MeOH/DCM yielded product as a golden oil
5.2. General procedure for the synthesis of compound (1)
5.2.1. 4-Formylnaphthalen-1-yl trifluoromethanesulfonate
4-Hydroxy-1-naphthaldehyde (250 mg, 1.45 mmol) and Et3N
(0.4 mL, 2.9 mmol) in anhydrous DCM (20 mL) were cooled
to ꢀ78 ꢁC. Tf2O (0.3 mL, 1.74 mmol) was slowly added to the
mixture and was stirred for 30 min at ꢀ78 ꢁC. Reaction was then
quickly diluted with additional DCM and washed with saturated
NaHCO3. Organic layer was dried over sodium sulfate and
concentrated. Chromatography using ISCO max gradient 30%
EtOAc/hexane yielded product as a brown oil (192 mg, 44% yield);
(43 mg, 67% yield); 1H NMR (400 MHz) (CD3OD)
d
8.12 (d, J ¼ 8.0 Hz,
1H), 7.89 (d, J ¼ 8.0 Hz, 1H), 7.56e7.49 (m, 4H), 7.42e7.38 (m, 1H),
7.34e7.32 (m, 3H), 4.30 (s, 2H), 1.39 (s, 9H); 13C NMR (100 MHz)
(CD3OD)
d 151.4, 141.2, 139.2, 138.1, 133.4, 132.8, 130.8, 128.0, 127.6,
127.2, 126.7, 126.3, 125.5, 124.4, 43.9, 35.5, 31.9; HRMS (ESI): calcd
for C21H24N (M þ H)þ 290.1903, found 290.1903.
1H NMR (400 MHz) (CDCl3)
d
10.28 (s, 1H), 9.18 (d, J ¼ 8.0 Hz, 1H),
5.3. General procedure for the synthesis of compound (2)
8.06e8.04 (m, 1H), 7.90 (d, J ¼ 8.0 Hz, 1H), 7.71e7.61 (m, 2H), 7.51
(d, J ¼ 8.0 Hz, 1H); 13C NMR (100 MHz) (CDCl3)
d
191.8, 149.5, 135.6,
5.3.1. 1-(4-(t-Butyl)phenyl)-4-(2-nitrovinyl)naphthalene
132.2, 131.2, 130.4, 128.7, 126.5, 125.2, 121.2, 120.2e117.1 (m), 116.8.
4-(4-(t-Butyl)phenyl)-1-naphthaldehyde (5.2.2) (168 mg,
0.583 mmol) and NH4OAc (52 mg, 0.67 mmol) innitromethane (4 mL)
were refluxed at 102 ꢁC for 2 h. Solvents were then evaporated.
Chromatography using ISCO max gradient 10% EtOAc/hexane yielded
product as a yellow solid (160 mg, 83% yield); mp 151 ꢁC; 1H NMR
5.2.2. 4-(4-(t-Butyl)phenyl)-1-naphthaldehyde
4-Formylnaphthalen-1-yl trifluoromethanesulfonate (190 mg,
0.625 mmol), 4-t-butylphenylboronic acid (134 mg, 0.75 mmol),
Pd(OAc)2 (14 mg, 0.0625 mmol), XPhos (60 mg, 0.125 mmol), and
K2CO3 (259 mg, 1.875 mmol) in dioxane (6 mL) and H2O (3 mL)
were combined in a flask and degassed. Reaction was refluxed at
100 ꢁC for 1 h. Reaction was then cooled to RT, diluted with EtOAc,
and washed with saturated NaHCO3. Organic layer was collected,
dried over sodium sulfate, and concentrated. Chromatography
using ISCO max gradient 30% EtOAc/hexane yielded product as
a sticky golden oil (158 mg, 88% yield); 1H NMR (400 MHz) (CDCl3)
(400 MHz) (CDCl3)
d
8.84 (d, J ¼ 12.0 Hz, 1H), 8.13 (d, J ¼ 8.0 Hz, 1H),
7.97 (d, J ¼ 8.0 Hz, 1H), 7.74 (d, J ¼ 4.0 Hz, 1H), 7.61 (d, J ¼ 4.0 Hz, 1H),
7.60e7.56(m,1H),7.48e7.44(m, 3H),7.40(d, J¼8.0Hz,1H), 7.37e7.34
(m, 2H), 1.34 (s, 9H); 13C NMR (100 MHz) (CDCl3)
d 151.1, 145.1, 138.3,
136.8, 136.3, 132.2, 132.1, 129.6, 127.5, 126.7, 126.6, 126.2, 126.0, 124.4,
123.2, 34.7, 31.4; HRMS (ESI): calcd for C22H21NO2 (M)þ 331.1572,
found 331.1569.
d
10.45 (s, 1H), 9.41 (d, J ¼ 8.0 Hz, 1H), 8.08e8.05 (m, 2H), 7.75e7.72
5.3.2. 2-(4-(4-(t-Butyl)phenyl)naphthalen-1-yl)ethanamine (2)
To a cooled solution of 1-(4-(t-butyl)phenyl)-4-(2-nitrovinyl)
naphthalene (160 mg, 0.483 mmol) in anhydrous THF (5 mL) was
carefully added LAH (55 mg, 1.45 mmol) at 0 ꢁC. Reaction was then
stirred at RT overnight and quenched with H2O over an ice bath.
Reaction mixture was then diluted with EtOAc and washed with 1 N
NaOH solution. Organic layer was collected, dried over sodium
sulfate, and concentrated. Chromatography using ISCO max
gradient 10% MeOH/DCM/0.1% NH4OH yielded product as a tan
solid (75 mg, 51% yield); mp 101e102 ꢁC; 1H NMR (400 MHz)
(m, 1H), 7.63e7.55 (m, 4H), 7.47 (d, J ¼ 8.0 Hz, 2H), 1.46 (s, 9H); 13C
NMR (100 MHz) (CDCl3)
d 193.3, 151.2, 147.6, 136.9, 136.3, 132.1,
131.2, 130.5, 129.6, 128.8, 127.0, 126.9, 126.1, 125.4, 125.1, 34.8, 31.4;
HRMS (ESI): calcd for C21H21O (M þ H)þ 289.1587, found 289.1582.
5.2.3. (4-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanol
NaBH4 (48 mg, 1.26 mmol) was carefully added to a solution of
4-(4-(t-butyl)phenyl)-1-naphthaldehyde (120 mg, 0.42 mmol) in
EtOH (5 mL). Reaction was stirred at RT for 1 h then quenched with
acetone (5 drops), filtered, and concentrated. Chromatography
using ISCO max gradient 40% EtOAc/hexane yielded product as
a glassy white solid (95 mg, 78% yield); mp 114e115 ꢁC; 1H NMR
(400 MHz) (CDCl3)
7.62e7.38 (m, 8H), 5.22 (s, 2H), 1.46 (s, 9H); 13C NMR (100 MHz)
(CDCl3) 150.2, 140.9, 137.7, 135.5, 132.2, 131.6, 129.8, 127.1, 126.5,
(CD3OD)
d
8.18 (d, J ¼ 12.0 Hz, 1H), 7.90e7.88 (m, 1H), 7.55e7.50 (m,
3H), 7.43e7.39 (m, 2H), 7.37e7.34 (m, 2H), 7.31 (d, J ¼ 8.0 Hz, 1H),
3.30 (t, J ¼ 16.0 Hz, 2H), 3.07e3.03 (m, 2H), 1.41 (s, 9H); 13C NMR
d
8.23 (d, J ¼ 8.0 Hz, 1H), 8.05 (d, J ¼ 8.5 Hz, 1H),
(100 MHz) (CD3OD) d 151.3, 140.6, 139.4, 136.1, 133.6, 130.8, 127.9,
127.5, 127.4, 126.9, 126.6, 126.2, 125.0, 43.4, 37.1, 35.5, 31.9; HRMS
d
(ESI): calcd for C22H26N (M þ H)þ 304.2060, found 304.2052.
126.2, 125.9, 125.2, 125.1, 123.9, 63.8, 34.7, 31.5; HRMS (ESI): calcd
for C21H22NaO (M þ Na)þ 313.1563, found 313.1560.
5.4. General procedure for the synthesis of compound (3)
5.2.4. 1-(Azidomethyl)-4-(4-(t-butyl)phenyl)naphthalene
5.4.1. 1,3-Di-Boc-2-((4-(4-(t-butyl)phenyl)naphthalen-1-yl)methyl)
guanidine
(4-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanol (5.2.3) (40 mg,
0.14 mmol), PPh3 (60 mg, 0.23 mmol), and 1,3-bis(t-butox-
ycarbonyl)guanidine (70 mg, 0.27 mmol) in anhydrous toluene
(3 mL) at 0 ꢁC was added diisopropylazodicarboxylate (0.04 mL,
(4-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanol
(95
mg,
0.328 mmol) in anhydrous THF (3 mL) was cooled to 0 ꢁC. DPPA
(0.14 mL, 0.656 mmol) was then added drop-wise followed by DBU
(0.1 mL, 0.656 mmol). Reaction was kept stirring over ice and was
warmed to RT overnight. Reaction mixture was then poured into

402
C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
0.20 mmol) drop-wise over 15 min. Reaction was stirred at RT
overnight then concentrated to an oil residue. Chromatography
using ISCO max gradient 30% EtOAc/hexane yielded product as
a white fluffy solid (70 mg, 97% yield); mp 88e90 ꢁC; 1H NMR
Chromatography using ISCO max gradient 50% EtOAc/hexane yiel-
ded product as a glassy white residue (490 mg, 88% yield); 1H NMR
(300 MHz) (CDCl3)
d
10.45 (s, 1H), 9.29 (d, J ¼ 6.0 Hz, 1H), 8.24 (d,
J ¼ 9.0 Hz, 1H), 8.00 (d, J ¼ 9.0 Hz, 1H), 7.76e7.70 (m, 1H), 7.60e7.51
(m, 4H), 7.42e7.39 (m, 2H), 1.42 (s, 9H); HRMS (ESI): calcd for
C21H20NaO (M þ Na)þ 311.1412, found 311.1406.
(400 MHz) (CDCl3)
d
9.46 (bs, 1H), 9.39 (bs, 1H), 7.97 (d, J ¼ 8.4 Hz,
1H), 7.91 (d, J ¼ 8.0 Hz, 1H), 7.46e7.41 (m, 3H), 7.37e7.28 (m, 3H),
7.28 (d, J ¼ 7.4 Hz, 1H), 7.12 (d, J ¼ 7.4 Hz, 1H), 5.67 (s, 2H), 1.37
(s, 9H), 1.33 (s, 9H), 1.10 (s, 9H); 13C NMR (100 MHz) (CDCl3)
d
163.8,
5.6.2. (5-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanol
161.0, 155.2, 150.1, 139.2, 137.8, 133.7, 131.8, 131.0, 129.8, 127.0, 126.3,
125.7, 125.5, 125.1, 123.1, 121.6, 84.1, 79.0, 45.3, 34.6, 31.5, 28.3, 27.6;
HRMS (ESI): calcd for C32H42N3O4 (M þ H)þ 532.3175, found
532.3185.
A mixture of 5-(4-(t-butyl)phenyl)-1-naphthaldehyde (750 mg,
2.6 mmol) and NaBH4 (70 mg, 1.85 mmol) in 95% EtOH/MeOH
(20 mL) was stirred at RT for 1 h. Reaction was then filtered and
filtrate was concentrated. Residue was taken back up in EtOAc and
washed with saturated NaHCO3 solution followed by brine. Organic
layer was collected, dried over magnesium sulfate, and concen-
trated. Chromatography using ISCO max gradient 30% EtOAc/
hexane yielded product as a white solid (740 mg, 99% yield); mp
5.4.2. 2-((4-(4-(t-Butyl)phenyl)naphthalen-1-yl)methyl)guanidine (3)
To a cooled solution of 1,3-di-Boc-2-((4-(4-(t-butyl)phenyl)
naphthalen-1-yl)methyl)guanidine (70 mg, 0.13 mmol) in anhy-
drous DCM (0.5 mL) was slowly added TFA (0.5 mL). Reaction was
stirred at RT overnight then solvents were evaporated. Chroma-
tography using ISCO max gradient 10% MeOH/DCM/0.1% NH4OH
yielded product as a white solid (35 mg, 80% yield); mp 85e87 ꢁC;
81e83 ꢁC; 1H NMR (400 MHz) (CDCl3)
d
8.18 (d, J ¼ 8.5 Hz, 1H), 7.96
(d, J ¼ 8.6 Hz, 1H), 7.64e7.60 (m, 1H), 7.57e7.52 (m, 3H), 7.49 (dd,
J ¼ 7.0 Hz, J ¼ 1.2 Hz, 1H), 7.46e7.40 (m, 3H), 5.22 (s, 2H), 1.45
(s, 9H); 13C NMR (100 MHz) (CDCl3)
d 150.2, 141.0, 137.9, 136.4,
1H NMR (400 MHz) (CD3OD)
d
8.07 (d, J ¼ 8.4 Hz, 1H), 7.95
132.2, 131.6, 129.8, 128.6, 127.0, 126.9, 125.9, 125.4, 125.2, 123.0,
64.0, 34.6, 31.5; HRMS (ESI): calcd for C21H22NaO (M þ Na)þ
313.1568, found 313.1565.
(d, J ¼ 8.5 Hz, 1H), 7.65e7.61 (m, 1H), 7.57e7.48 (m, 4H), 7.43e7.37
(m, 3H), 4.93 (s, 2H), 1.42 (s, 9H); 13C NMR (100 MHz) (CD3OD)
d
158.9, 151.7, 142.6, 138.9, 133.6, 132.8, 131.9, 130.8, 128.1, 127.7,
127.4, 127.2, 126.4, 126.3, 124.3, 44.5, 35.5, 31.9; HRMS (ESI): calcd
5.6.3. 1-(Azidomethyl)-5-(4-(t-butyl)phenyl)naphthalene
for C22H26N3 (M þ H)þ 332.2121, found 332.2137.
(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanol
(66
mg,
0.23 mmol), NaN3 (18 mg, 0.27 mmol), and PPh3 (125 mg,
0.48 mmol) in DMF (4 mL) and CCl4 (1 mL) were heated to 90 ꢁC
overnight. Solvents were then evaporated without further purifi-
cation yielded product as a clear oil (50 mg, 69% yield); 1H NMR
5.5. General procedure for the synthesis of compound (4)
5.5.1. 1,3-Di-Boc-2-(2-(4-(4-(t-butyl)phenyl)naphthalen-1-yl)
ethyl)guanidine
(400 MHz) (CDCl3)
7.54e7.50 (m,1H), 7.44e7.38 (m, 4H), 7.35e7.28 (m, 3H), 4.72 (s, 2H),
1.33 (s, 9H); 13C NMR (100 MHz) (CDCl3)
150.3, 141.2, 137.7, 132.3,
d
7.95 (d, J ¼ 8.5 Hz, 1H), 7.79 (d, J ¼ 8.6 Hz, 1H),
2-(4-(4-(t-Butyl)phenyl)naphthalen-1-yl)ethanamine
(2)
(25 mg, 0.08 mmol), 1,3-di-Boc-2-(trifluoromethylsulfonyl)-guani-
dine (40 mg, 0.1 mmol), and Et3N (0.03 mL, 0.22 mol) in anhydrous
DCM (4 mL) were stirred at RT overnight then concentrated to an oil
residue. Chromatography using ISCO max gradient 10% EtOAc/
hexane yielded product as a white solid (38 mg, 84% yield); 1H NMR
d
131.8, 131.1, 129.8, 127.8, 127.3, 127.2, 126.2, 125.2, 125.1, 122.8, 53.4,
34.7, 31.5.
5.6.4. (5-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanamine (5)
1-(Azidomethyl)-5-(4-(t-butyl)phenyl)naphthalene (50 mg,
crude material) was combined in a flask with polymer supported
(3 mmol/g loading) PPh3 (300 mg), THF (5 mL), and H2O (0.5 mL).
Reaction was stirred overnight at RT. Resin was then filtered off and
filtrate concentrated. Chromatography using ISCO max gradient
10% MeOH/DCM yielded product as an oily residue (34 mg, 74%
(300 MHz) (CDCl3)
d
8.50 (m, 1H), 8.35 (d, J ¼ 9.0 Hz, 1H), 8.18
(d, J ¼ 6.0 Hz, 1H), 7.56e7.34 (m, 7H), 3.82 (m, 2H), 3.42
(t, J ¼ 6.0 Hz, 2H), 1.55 (s, 9H), 1.49 (s, 9H), 1.42 (s, 9H).
5.5.2. 2-(2-(4-(4-(t-Butyl)phenyl)naphthalen-1-yl)ethyl)guanidine
(4)
To a cooled solution of 1,3-di-Boc-2-(2-(4-(4-(t-butyl)phenyl)
naphthalen-1-yl)ethyl)guanidine (36 mg, 0.07 mmol) in anhydrous
DCM (0.8 mL) was slowly added TFA (0.8 mL). Reaction was stirred
at RT overnight then solvents were evaporated. Chromatography
using ISCO max gradient 10% MeOH/DCM/0.1% NH4OH yielded
product as a white solid (21 mg, 91% yield); mp 115e116 ꢁC; 1H NMR
yield); 1H NMR (400 MHz) (CDCl3)
(d, J ¼ 8.0 Hz, 1H), 7.51 (m, 1H), 7.44e7.29 (m, 7H), 4.31 (s, 2H), 1.58
(bs, 2H), 1.34 (s, 9H); 13C NMR (100 MHz) (CD3OD)
151.5, 142.5,
139.5, 138.6, 133.5, 132.9, 130.8, 127.9, 127.0, 126.8, 126.5, 126.2,
d
8.03 (d, J ¼ 8.0 Hz, 1H), 7.80
d
126.1, 123.5, 44.0, 35.5, 31.9; HRMS (ESI): calcd for C21H23
N
(M þ H)þ 290.1903, found 290.1891.
(300 MHz) (CD3OD)
d
8.16 (d, J ¼ 6.0 Hz, 1H), 7.92 (d, J ¼ 6.0 Hz, 1H),
7.57 (m, 3H), 7.47 (m, 2H), 7.38 (m, 3H), 3.66 (t, J ¼ 6.0 Hz, 2H), 3.44
5.7. General procedure for the synthesis of compound (6)
(t, J ¼ 6.0 Hz, 2H), 1.43 (s, 9H); 13C NMR (100 MHz) (CD3OD)
d 158.7,
151.5, 141.2, 139.2, 134.6, 133.6, 133.5, 130.8, 128.1, 127.7, 127.6, 127.2,
126.8, 126.3, 124.6, 43.1, 35.5, 33.0, 31.9; HRMS (ESI): calcd for
C23H28N3 (M þ H)þ 346.2278, found 346.2284.
5.7.1. 2-(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)acetonitrile
To a solution of (5-(4-(t-butyl)phenyl)naphthalen-1-yl)meth-
anol (5.6.2) (1.0 g, 3.4 mmol) and Et3N (0.8 mL, 5.8 mmol) in DCM
(25 mL) at 0 ꢁC was slowly added MsCl (0.33 mL, 4.3 mmol). The
reaction was stirred at 0 ꢁC for 30 min then quenched with satu-
rated NaHCO3 and extracted with EtOAc. Organic layer was
collected, dried over magnesium sulfate, and concentrated to an oil.
To this oil residue was added KCN (310 mg, 4.8 mmol) in DMSO
(10 mL). The reaction was stirred at RT overnight then diluted with
H2O and extracted with EtOAc. Extract was then washed with
additional H2O followed by brine. Organic layer was collected, dried
over magnesium sulfate, and concentrated. Chromatography using
ISCO max gradient 50% EtOAc/hexane yielded product as a pale oil
5.6. General procedure for the synthesis of compound (5)
5.6.1. 5-(4-(t-Butyl)phenyl)-1-naphthaldehyde
5-Bromo-1-naphthaldehyde (500 mg, 2.1 mmol), 4-t-butyl-
phenylboronic acid (470 mg, 2.6 mmol), and K2CO3 (880 mg,
6.4 mmol) in dioxane (15 mL) and H2O (3 mL) were degassed and
Pd(PPh3)4 (73 mg, 0.06 mmol) was quickly added. Reaction was
then refluxed at 100 ꢁC for 5 h then cooled to RT. Solution was dried
over
magnesium
sulfate,
filtered,
and
concentrated.

C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
403
(510 mg, 50% yield); 1H NMR (400 MHz) (CDCl3)
d
8.01 (d, J ¼ 8.6 Hz,
133.5, 130.8, 129.6, 129.5, 128.4, 127.6, 127.4, 126.7, 126.3, 123.2,
54.8, 35.5, 31.8; HRMS (ESI): calcd for C22H25N2 (M þ H)þ
317.2012, found 317.2019.
1H), 7.91 (d, J ¼ 8.5 Hz, 1H), 7.70e7.63 (m, 2H), 7.57e7.53 (m, 3H),
7.46e7.42 (m, 3H), 4.21 (s, 2H), 1.45 (s, 9H); 13C NMR (100 MHz)
(CDCl3)
d 150.5, 141.5, 137.5, 132.2, 131.2, 129.8, 127.5, 127.4, 126.6,
126.4, 125.9, 125.4, 125.2, 121.7, 117.7, 34.7, 31.4, 22.1; HRMS (ESI):
calcd for C22H21N (M)þ 299.1674, found 299.1672.
5.9. General procedure for the synthesis of compound (8)
5.7.2. 2-(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)ethanamine (6)
LAH (1.0M/THF, 0.9 mL) was added drop-wise to a cooled 0 ꢁC
solution of 2-(5-(4-(t-butyl)phenyl)naphthalen-1-yl)acetonitrile
(85 mg, 0.28 mmol) in anhydrous THF (5 mL). The resultant
mixture was then refluxed for 7 h. Reaction was cooled to 0 ꢁC and
carefully treated with aqueous NaOH solution and extracted with
EtOAc. Organic layer was collected, dried over magnesium sulfate,
and concentrated. Chromatography using ISCO max gradient 20%
1.5% NH4OH/MeOH/DCM solution yielded product as a pale oil
5.9.1. 1,3-Di-Boc-2-((5-(4-(t-butyl)phenyl)naphthalen-1-yl)methyl)
guanidine
(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanol (5.6.2) (106 mg,
0.364 mmol), PPh3 (100 mg, 0.38 mmol), and 1,3-bis(t-butox-
ycarbonyl)guanidine (132 mg, 0.52 mmol) in anhydrous toluene
(3 mL) at 0 ꢁC was added diisopropylazodicarboxylate (0.1 mL,
0.52 mmol) drop-wise over 15 min. Reaction was stirred at RT
overnight then 2 drops H2O were added, and the solution was
concentrated. Chromatography using ISCO max gradient 30% EtOA-
c/hexane yielded product as a yellow solid (104 mg, 54% yield); 1H
(15 mg, 17% yield); 1H NMR (300 MHz) (CDCl3)
d 8.99 (d,
J ¼ 6.0 Hz, 1H), 7.77 (d, J ¼ 6.0 Hz, 1H), 7.50e7.41 (m, 3H), 7.34 (m,
NMR (400 MHz) (CDCl3) d 9.55 (bs, 1H), 9.50 (bs, 1H), 8.06 (d,
3H), 7.29 (m, 2H), 3.21 (t, J ¼ 6.0 Hz, 2H), 3.08 (t, J ¼ 6.0 Hz, 2H),
J ¼ 8.0 Hz, 1H), 7.87 (d, J ¼ 8.0 Hz, 1H), 7.59e7.51 (m, 3H), 7.47e7.43
(m, 2H), 7.39e7.37 (m, 2H), 7.18 (d, J ¼ 4.0 Hz, 1H), 5.77 (s, 2H), 1.46
(s, 9H), 1.43 (s, 9H), 1.20 (s, 9H).
1.92 (bs, 2H), 1.34 (s, 9H); 13C NMR (100 MHz) (CD3OD)
d 151.3,
140.6, 139.4, 136.1, 133.6, 130.8, 127.9, 127.5, 127.4, 126.9, 126.2,
125.0, 43.5, 37.1, 35.5, 31.9; HRMS (ESI): calcd for C22H25
N
(M þ H)þ 304.2060, found 304.2046.
5.9.2. 2-((5-(4-(t-Butyl)phenyl)naphthalen-1-yl)methyl)guanidine (8)
1,3-Di-Boc-2-((5-(4-(t-butyl)phenyl)naphthalen-1-yl)methyl)
guanidine (20 mg, 0.07 mmol) was stirred at RT in a mixture of
anhydrous DCM (0.5 mL) and TFA (0.5 mL) overnight. Solvents were
then evaporated. Chromatography using ISCO max gradient 20% 3%
NH4OH/MeOH/DCM solution yielded product as a white solid
(17 mg, 74% yield); mp 160e163 ꢁC; 1H NMR (400 MHz) (CD3OD)
5.8. General procedure for the synthesis of compound (7)
5.8.1. 1-(Bromomethyl)-5-(4-(t-butyl)phenyl)naphthalene
(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)methanol
(5.6.2)
(600 mg, 2.0 mmol) in anhydrous DCM (15 mL) was cooled to 0 ꢁC
and PBr3 (0.4 mL) was added drop-wise. The reaction was stirred at
d
8.00e7.60 (m, 5H), 7.56e7.36 (m, 5H), 4.89 (s, 2H), 1.41 (s, 9H); 13
NMR (100 MHz) (CD3OD) 158.8, 151.7, 142.7, 139.1, 133.6, 132.9,
C
0
ꢁC for 1 h then quenched with saturated NaHCO3 and extracted
d
with DCM. Organic layer was collected, dried over magnesium
sulfate, and concentrated to yield product as a pale oil (670 mg, 86%
132.8, 130.8, 128.3, 128.2, 127.3, 126.7, 126.4, 126.3, 126.3, 44.7, 35.5,
31.8; HRMS (ESI): calcd for C22H25N3 (M þ H)þ 332.2121, found
332.2104.
yield); 1H NMR (300 MHz) (CDCl3)
d
8.21 (d, J ¼ 9.0 Hz, 1H), 8.00 (d,
J ¼ 9.0 Hz, 1H), 7.69 (m, 2H), 7.60e7.50 (m, 3H), 7.46e7.36 (m, 3H),
5.06 (s, 2H), 1.45 (s, 9H).
5.10. General procedure for the synthesis of compound (9)
5.8.2. 2-(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)acetonitrile
1-(Bromomethyl)-5-(4-(t-butyl)phenyl)naphthalene (200 mg,
0.57 mmol) and KCN (55 mg, 0.85 mmol) in DMSO (6 mL) were
stirred at RT overnight. Reaction was then diluted with H2O and
extracted with ether. Organic layer was collected, dried over
magnesium sulfate, and concentrated. Chromatography using ISCO
max gradient 20% EtOAc/hexane yielded product as a pale oil
5.10.1. 1,3-Di-Boc-2-(2-(5-(4-(t-butyl)phenyl)naphthalen-1-yl)
ethyl)guanidine
2-(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)ethanamine
(5.7.2)
(35 mg, 0.12 mmol), 1,3-di-Boc-2-(trifluoromethylsulfonyl)-guani-
dine (55 mg, 0.14 mmol), and Et3N (0.04 mL, 0.29 mmol) in anhy-
drous DCM (6 mL) were stirred at RT overnight. Solvents were then
evaporated. Chromatography using ISCO max gradient 20% EtOAc/
hexane yielded product as a white solid (51 mg, 81% yield); 1H NMR
(120 mg, 74% yield); 1H NMR (400 MHz) (CDCl3)
d 8.01 (d,
J ¼ 8.6 Hz, 1H), 7.91 (d, J ¼ 8.5 Hz, 1H), 7.70e7.63 (m, 2H), 7.57e
7.53 (m, 3H), 7.46e7.42 (m, 3H), 4.21 (s, 2H), 1.45 (s, 9H); 13C
(300 MHz) (CDCl3)
d
8.50 (t, J ¼ 3.0 Hz, 1H), 8.30 (d, J ¼ 9.0 Hz, 1H),
NMR (100 MHz) (CDCl3)
d
150.5, 141.5, 137.5, 132.2, 131.2, 129.8,
7.87 (dd, J ¼ 6.0 Hz, J ¼ 3.0 Hz, 1H), 7.62e7.50 (m, 3H), 7.46e7.33 (m,
4H), 3.80 (m, 2H), 3.43 (t, J ¼ 6.0 Hz, 2H), 1.56 (s, 9H), 1.43 (s, 9H),
1.41 (s, 9H).
127.5, 127.4, 126.6, 126.4, 125.9, 125.4, 125.2, 121.7, 117.7, 34.7, 31.4,
22.1; HRMS (ESI): calcd for C22H21
299.1672.
N
(M)þ 299.1674, found
5.10.2. 2-(2-(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)ethyl)
guanidine (9)
5.8.3. 2-(5-(4-(t-Butyl)phenyl)naphthalen-1-yl)acetimidamide (7)
A solution of 2-(5-(4-(t-butyl)phenyl)naphthalen-1-yl)aceto-
nitrile (120 mg, 0.4 mmol) in anhydrous Et2O (2 mL) was cooled
to 0 ꢁC and treated with 4 N HCl/dioxane solution (2 mL).
Reaction was stirred at 0 ꢁC for 4 h. The mixture was then placed
in the refrigerator overnight. The precipitated solids were filtered
out then treated with NH4OH/EtOH (6 mL) and heated to reflux
for 6 h. Solvents were then evaporated. Chromatography using
ISCO max gradient 20% 3% NH4OH/MeOH/DCM solution yielded
product as pale solid (37 mg, 29% yield); mp 266e269 ꢁC; 1H
1,3-Di-Boc-2-(2-(5-(4-(t-butyl)phenyl)naphthalen-1-yl)ethyl)
guanidine (40 mg, 0.09 mmol) was stirred at RT in a mixture of
anhydrous DCM (0.8 mL) and TFA (0.8 mL) overnight. Solvents were
then evaporated. Chromatography using ISCO max gradient 15% 3%
NH4OH/MeOH/DCM solution yielded product as a white solid
(29 mg, 96% yield); mp 185 ꢁC; 1H NMR (300 MHz) (CD3OD)
d
8.13 (d, J ¼ 9.0 Hz, 1H), 7.81 (d, J ¼ 9.0 Hz, 1H), 7.65e7.55 (m, 3H),
7.45e7.36 (m, 5H), 3.66 (t, J ¼ 6.0 Hz, 2H), 3.46 (t, J ¼ 6.0 Hz, 2H),
1.43 (s, 9H); 13C NMR (100 MHz) (CD3OD)
158.7,151.6,142.6, 139.4,
d
NMR (300 MHz) (CD3OD)
(m, 3H), 7.52e7.45 (m, 3H), 7.40 (m, 1H), 4.41 (s, 2H), 1.44 (s, 9H);
13C NMR (100 MHz) (CD3OD)
171.8, 151.8, 142.9, 139.0, 133.7,
d
7.96 (m, 2H), 7.68 (m, 1H), 7.59e7.57
135.5, 133.7, 133.6, 130.8, 128.1, 127.9, 126.8, 126.7, 126.5, 126.3,
123.7, 43.2, 35.5, 33.3, 31.9; HRMS (ESI): calcd for C23H28N3
(M þ H)þ 346.2278, found 346.2281.
d

404
C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
5.11. General procedure for the synthesis of compound (10)
and the solution was concentrated. Solid was then dissolved in
DCM and passed through silica column and resulting crude
product was then re-dissolved in anhydrous DCM (1.5 mL) and
cooled to 0 ꢁC. TFA (1.5 mL) was then added. Reaction was taken
off ice bath and stirred at RT for 2 h then solvents were evapo-
rated. Solid was then taken back up in DCM and precipitate was
filtered off yielded product as a gummy tan solid (18 mg, 20%
5.11.1. 5-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-1-
naphthaldehyde
To a stirred mixture of 5-bromo-naphthaldehyde (500 mg,
2.21 mmol), diborane (810 mg, 3.19 mmol), and KOAc (800 mg,
6.3 mmol) in anhydrous DMF (10 mL) was added Pd(OAc)2 (20 mg,
0.09 mmol). Reaction mixture was degassed then heated at 80 ꢁC
for 6 h. Reaction was cooled to RT and diluted with EtOAc and
washed with brine. Organic layer was collected, dried over
magnesium sulfate, and concentrated. Chromatography using ISCO
max gradient 15% EtOAc/hexane yielded product as a clear oil
yield over 2 steps); 1H NMR (400 MHz) (CD3OD)
d 8.02e8.00
(m, 1H), 7.90e7.88 (m, 1H), 7.67e7.63 (m, 1H), 7.54e7.50
(m, 2H), 7.47e7.42 (m, 1H), 7.33e7.31 (m, 2H), 7.24e7.22
(m, 2H), 4.93 (s, 2H), 2.06e1.99 (m, 1H), 1.06e1.02 (m, 2H),
0.79e0.76 (m, 2H); 13C NMR (100 MHz) (CD3OD)
d
158.9, 144.9,
(410 mg, 68% yield); 1H NMR (400 MHz) (CDCl3)
d 10.40 (s, 1H), 9.42
142.7, 139.1, 133.6, 132.8, 131.0, 129.4, 128.2, 128.1, 127.3, 126.7,
(d, J ¼ 8.0 Hz, 1H), 9.12 (d, J ¼ 8.0 Hz, 1H), 8.21 (d, J ¼ 8.0 Hz, 1H),
126.6, 126.4, 123.3, 44.7, 16.0, 9.7; HRMS (ESI): calcd for C21H22N
8.01 (d, J ¼ 8.0 Hz, 1H), 7.73e7.69 (m, 2H), 1.46 (s, 12H).
(M þ H)þ 316.1808, found 316.1805.
5.11.2. 5-(4-Bromophenyl)-1-naphthaldehyde
5.12. General procedure for the synthesis of compound (11)
A flask containing 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)-1-naphthaldehyde (209 mg, 0.7 mmol), 4-bromoiodobenzene
(230 mg, 0.8 mmol), and K2CO3 (200 mg, 1.4 mmol) in dioxane
(8 mL) and H2O (1.5 mL) was purged with N2. Pd(PPh3)4 (40 mg,
0.03 mmol) was then quickly added and resultant mixture
was heated at 100 ꢁC for 5 h. Reaction was cooled to RT, dried
over magnesium sulfate, and concentrated. Chromatography using
ISCO max gradient 50% EtOAc/hexane yielded product as a light
5.12.1. 5-(4-Chlorophenyl)-1-naphthaldehyde
A flask containing 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)-1-naphthaldehyde (200 mg, 0.7 mmol), 4-chlorobromobenzene
(160 mg, 0.8 mmol), and K2CO3 (200 mg, 1.4 mmol) in dioxane
(6 mL) and H2O (1.5 mL) was purged with N2. Pd(PPh3)4 (40 mg,
0.03 mmol) was then quickly added and resultant mixture was
heated at 100 ꢁC for 5 h. Reaction was cooled to RT, dried over
magnesium sulfate, and concentrated. Chromatography using ISCO
max gradient 15% EtOAc/hexane yielded product as a pale solid
yellow solid (142 mg, 65% yield); 1H NMR (300 MHz) (CDCl3)
d 10.50
(s, 1H), 8.15 (d, J ¼ 9.0 Hz, 1H), 8.05 (d, J ¼ 9.0 Hz, 1H), 7.76 (m, 2H),
7.69e7.60 (m, 3H), 7.55 (d, J ¼ 9.0 Hz, 1H), 7.39e7.36 (m, 2H).
(160 mg, 84% yield); 1H NMR (300 MHz) (CDCl3)
d 10.50 (s, 1H), 8.15
(d, J ¼ 9.0 Hz, 1H), 8.06 (d, J ¼ 9.0 Hz, 1H), 7.77 (m, 1H), 7.63 (m, 1H),
5.11.3. (5-(4-Bromophenyl)naphthalen-1-yl)methanol
7.56e7.50 (m, 4H), 7.44e7.14 (m, 2H).
5-(4-Bromophenyl)-1-naphthaldehyde (140 mg, 0.45 mmol)
and NaBH4 (12 mg, 0.32 mmol) in 95% EtOH/MeOH (8 mL) were
stirred at RT for 2 h. Reaction mixture was then filtered and filtrate
concentrated. Chromatography using ISCO max gradient 30%
EtOAc/hexane yielded product as a clear oil (140 mg, quantitative);
5.12.2. (5-(4-Chlorophenyl)naphthalen-1-yl)methanol
5-(4-Chlorophenyl)-1-naphthaldehyde (160 mg, 0.6 mmol) and
NaBH4 (16 mg, 0.42 mmol) in 95% EtOH/MeOH (10 mL) were stirred
at RT for 1 h. Reaction mixture was then filtered and filtrate
concentrated. Residue was then taken back up in DCM and washed
with saturated NaHCO3 solution followed by brine. Organic layer
was collected, dried over magnesium sulfate, and concentrated.
Chromatography using ISCO max gradient 30% EtOAc/hexane yiel-
ded product as a clear oil (160 mg, quantitative); 1H NMR
1H NMR (300 MHz) (CDCl3)
d
8.11 (d, J ¼ 9.0 Hz, 1H), 7.74 (d,
J ¼ 9.0 Hz, 1H), 7.56e7.47 (m, 4H), 7.36e7.26 (m, 4H), 5.14 (s, 2H).
5.11.4. (5-(4-Cyclopropylphenyl)naphthalen-1-yl)methanol
(5-(4-Bromophenyl)naphthalen-1-yl)methanol
(130
mg,
0.415 mmol), cyclopropylboronic acid (71 mg, 0.83 mmol),
Pd(OAc)2 (5 mg, 0.021 mmol), tricyclohexylphosphine (12 mg,
0.0415 mmol), and K3PO4 (308 mg, 1.45 mmol) were combined in
a flask with toluene (3 mL) and H2O (1 mL) and degassed. Reaction
mixture was then refluxed at 100 ꢁC for 3 h. Solution was cooled to
RT then diluted with EtOAc and washed with saturated NaHCO3.
Organic layer was dried over sodium sulfate and concentrated.
Chromatography using ISCO max gradient 35% EtOAc/hexane yiel-
ded product as a brown oil (86 mg, 75% yield); 1H NMR (400 MHz)
(300 MHz) (CDCl3)
7.66e7.58 (m, 2H), 7.52e7.48 (m, 6H), 5.23 (s, 2H); 13C NMR
(100 MHz) (CDCl3) 139.7, 139.4, 136.6, 133.4, 131.9, 131.6, 131.4,
d
8.21 (d, J ¼ 9.0 Hz, 1H), 7.84 (d, J ¼ 9.0 Hz, 1H),
d
128.5, 127.0, 126.3, 125.8, 125.7,125.4, 123.6, 63.8; HRMS (ESI): calcd
for C17H14ClO (M þ H)þ 291.0547, found 291.0541.
5.12.3. 1,3-Di-Boc-2-((5-(4-chlorophenyl)naphthalen-1-yl)methyl)
guanidine
To a solution of (5-(4-chlorophenyl)naphthalen-1-yl)methanol
(50 mg, 0.186 mmol), PPh3 (73 mg, 0.278 mmol), and 1,3-bis(t-
butoxycarbonyl)guanidine (96 mg, 0.37 mmol) in anhydrous toluene
(3 mL) at 0 ꢁC was added diisopropylazodicarboxylate (0.06 mL,
0.31 mmol) drop-wise over 15 min. Reaction was stirred at RT
overnight, and the solution was then concentrated to an oil residue.
Chromatography using ISCO max gradient 30% EtOAc/hexane yiel-
ded product as a pale solid (46 mg, 48% yield); 1H NMR (300 MHz)
(CDCl3)
d
8.17e8.15 (m, 1H), 7.96e7.94 (m, 1H), 7.61 (dd, J ¼ 8.0 Hz,
J ¼ 8.0 Hz, 1H), 7.56e7.53 (m, 2H), 7.49e7.47 (m, 1H), 7.43e7.40 (m,
2H), 7.25e7.23 (m, 2H), 5.19 (s, 2H), 2.08e2.01 (m,1H),1.11e1.06 (m,
2H), 0.87e0.83 (m, 2H); 13C NMR (100 MHz) (CDCl3)
d 143.2, 138.0,
136.5, 132.2, 131.6, 130.1, 130.1, 138.3, 126.8, 125.8, 125.6, 125.4,
125.3, 123.0, 63.9, 15.3, 9.4; HRMS (ESI): calcd for C20H18NaO
(M þ Na)þ 297.1250, found 297.1251.
(CDCl3)
d
8.06 (d, J ¼ 9.0 Hz,1H), 7.75 (d, J ¼ 9.0 Hz,1H), 7.61e7.37 (m,
5.11.5. 2-((5-(4-Cyclopropylphenyl)naphthalen-1-yl)methyl)
guanidine (10)
7H), 7.21 (d, J ¼ 6.0 Hz, 1H), 5.80 (s, 2H), 1.47 (s, 9H), 1.21 (s, 9H).
To
a
solution of (5-(4-cyclopropylphenyl)naphthalen-1-yl)
5.12.4. 2-((5-(4-Chlorophenyl)naphthalen-1-yl)methyl)guanidine (11)
1,3-Di-Boc-2-((5-(4-chlorophenyl)naphthalen-1-yl)methyl)
guanidine (46 mg, 0.09 mmol) in a mixture of anhydrous DCM
(0.8 mL) and TFA (0.8 mL) was stirred at RTovernight. Solvents were
then evaporated. Chromatography using ISCO max gradient 20% 3%
NH4OH/MeOH/DCM solution yielded product as a white solid
methanol (80 mg, 0.292 mmol), PPh3 (115 mg, 0.584 mmol), and
1,3-bis(t-butoxycarbonyl)guanidine (151 mg, 0.438 mmol) in
anhydrous toluene (3 mL) at 0 ꢁC was added diisopropylazodi-
carboxylate (0.09 mL, 0.438 mmol) drop-wise over 15 min.
Reaction was stirred for 3 h at RT then 2 drops H2O were added,

C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
405
(27 mg, 78% yield); mp 106e109 ꢁC; 1H NMR (300 MHz) (DMSO-d6)
131.6 (m), 130.4, 129.8, 129.4, 127.0, 126.2, 125.9, 125.8, 125.5,
d
8.08 (m, 2H), 7.75e7.59 (m, 4H), 7.53e7.46 (m, 4H), 4.89
125.3e125.2 (m), 124.0, 123.0, 63.9.
(d, J ¼ 3.0 Hz, 2H); 13C NMR (100 MHz) (CD3OD)
d 158.9, 141.3,140.7,
134.7, 133.3, 132.8, 132.6, 129.6, 128.4, 127.6, 127.3, 126.8, 123.9,
44.6; HRMS (ESI): calcd C18H17ClN3 (M þ H)þ 310.1106, found
310.1110.
5.14.3. 2-(5-(4-(Trifluoromethyl)phenyl)naphthalen-1-yl)
acetonitrile
(5-(4-(Trifluoromethyl)naphthalen-1-yl)methanol (300 mg,
0.99 mmol) in anhydrous DCM (10 mL) was cooled to 0 ꢁC and PBr3
(0.14 mL) was added drop-wise. The reaction was stirred at 0 ꢁC for
1 h then quenched with saturated NaHCO3 and extracted with DCM.
Organic layer was collected, dried over magnesium sulfate, and
concentrated to yield crude product as a pale gum which was taken
forward without further purification. This crude 1-(bromomethyl)-
5-(4-(trifluoromethyl)phenyl)naphthalene (300 mg, 0.82 mmol) and
KCN (100 mg, 1.5 mmol) in DMSO were stirred at RT overnight.
Reaction was then diluted with H2O and extracted with ether.
Organic layer was collected, dried over magnesium sulfate, and
concentrated. Chromatography using ISCO max gradient 20% EtOAc/
hexane yielded product as a white solid (260 mg, 85% yield over two
5.13. General procedure for the synthesis of compound (12)
5.13.1. 1,3-Di-Boc-2-((5-(4-bromophenyl)naphthalen-1-yl)methyl)
guanidine
To a solution of (5-(4-bromophenyl)naphthalen-1-yl)methanol
(5.11.3) (40 mg, 0.128 mmol), PPh3 (60 mg, 0.23 mmol), and 1,3-
bis(t-butoxycarbonyl)guanidine (66 mg, 0.26 mmol) in anhydrous
toluene (3 mL) at 0 ꢁC was added diisopropylazodicarboxylate
(0.04 mL, 0.20 mmol) drop-wise over 15 min. Reaction was stirred
at RT overnight, and the solution was then concentrated to an oil
residue. Chromatography using ISCO max gradient 30% EtOAc/
hexane yielded product as a pale solid (46 mg, 47% yield); 1H NMR
steps); mp 44e45 ꢁC; 1H NMR (400 MHz) (CDCl3)
d 7.87 (d,
(300 MHz) (CDCl3)
d
9.60 (bs, 1H), 9.50 (bs, 1H), 8.06 (d, J ¼ 9.0 Hz,
J ¼ 8.6 Hz, 1H), 7.73 (d, J ¼ 8.6 Hz, 1H), 7.69e7.68 (m, 2H), 7.62e7.58
1H), 7.75 (d, J ¼ 9.0 Hz, 1H), 7.66e7.37 (m, 7H), 7.21 (d, J ¼ 6.0 Hz,
(m,1H), 7.56 (d, J ¼ 7.2 Hz, 1H), 7.52e7.51 (m, 2H), 7.43e7.34 (m, 2H),
1H), 5.78 (s, 2H), 1.47 (s, 9H), 1.22 (s, 9H).
4.12 (s, 2H); 13C NMR (100 MHz) (CDCl3)
d 144.2, 140.0, 131.8, 131.2,
130.4, 130.0, 129.7, 127.5, 126.8, 126.7, 126.5, 126.3, 125.9, 125.3, 122.7,
117.5, 22.1; HRMS (ESI): calcd for C19H12F3NNa (M þ Na)þ 334.0820,
found 334.0823.
5.13.2. 2-((5-(4-Bromophenyl)naphthalen-1-yl)methyl)guanidine (12)
1,3-Di-Boc-2-((5-(4-bromophenyl)naphthalen-1-yl)methyl)
guanidine (34 mg, 0.06 mmol) in a mixture of anhydrous DCM
(0.8 mL) and TFA (0.8 mL) was stirred at RTovernight. Solvents were
then evaporated. Chromatography using ISCO max gradient 20% 3%
NH4OH/MeOH/DCM solution yielded product as a white solid
(18 mg, 75% yield); mp 124e127 ꢁC; 1H NMR (300 MHz) (DMSO-d6)
5.14.4. 2-(5-(4-(Trifluoromethyl)phenyl)naphthalen-1-yl)
acetimidamide (13)
A solution of 2-(5-(4-(trifluoromethyl)phenyl)naphthalen-1-
yl)acetonitrile (100 mg, 0.32 mmol) in anhydrous Et2O (2 mL)
was cooled to 0 ꢁC and treated with 4 N HCl/dioxane solution
(2 mL). Reaction was stirred at 0 ꢁC for 4 h. The mixture was then
placed in the refrigerator overnight. The precipitated solids were
filtered out then treated with NH4OH/EtOH (5 mL) and heated to
reflux for 6 h. Solvents were then evaporated. Chromatography
using ISCO max gradient 20% 3% NH4OH/MeOH/DCM solution
yielded product as a pale gummy solid (37 mg, 29% yield); mp
d
8.02 (m, 2H), 7.75e7.67 (m, 2H), 7.52 (m, 2H), 7.12 (m, 4H), 4.90
(s, 2H); 13C NMR (100 MHz) (CD3OD)
d
158.9, 141.3, 141.2, 133.2,
133.1, 132.9, 132.8, 132.6, 131.0, 128.3, 127.6, 127.3, 126.8, 124.0,
122.7, 44.6; HRMS (ESI): calcd for C18H17BrN3 (M þ H)þ 354.0600,
found 354.0599.
5.14. General procedure for the synthesis of compound (13)
1H NMR (300 MHz) (CDCl3)
(d, J ¼ 9.0 Hz, 2H), 7.76e7.67 (m, 3H), 7.62e7.50 (m, 4H), 4.44
(s, 2H); 13C NMR (100 MHz) (CD3OD)
171.7, 141.2, 133.5, 133.2,
d
8.06 (d, J ¼ 6.0 Hz, 1H), 7.86
5.14.1. 5-(4-(Trifluoromethyl)phenyl)-1-naphthaldehyde
5-Bromo-1-naphthaldehyde (500 mg, 2.1 mmol), 4-
trifluoromethylphenylboronic acid (620 mg, 3.2 mmol), and
K2CO3 (880 mg, 6.4 mmol) in dioxane (15 mL) and H2O (3 mL) were
degassed and Pd(PPh3)4 (73 mg, 0.06 mmol) was quickly added.
Reaction was then refluxed at 100 ꢁC for 5 h then cooled to RT.
Solution was dried over magnesium sulfate, filtered, and concen-
trated. Chromatography using ISCO max gradient 30% EtOAc/
hexane yielded product as a pale solid (560 mg, 88% yield); mp 78e
d
131.8, 130.2, 130.0, 129.8, 129.4, 128.6, 127.8, 127.6, 127.4, 127.3,
126.4e126.3 (m), 124.2, 37.2; HRMS (ESI): calcd for C19H16F3N2
(M þ H)þ 329.1260, found 329.1244.
5.15. General procedure for the synthesis of compound (14)
5.15.1. 1,3-Di-Boc-2-((5-(4-(Trifluoromethyl)phenyl)naphthalen-1-
yl)methyl)guanidine
80 ꢁC; 1H NMR (400 MHz) (CDCl3)
d
10.45 (s, 1H), 9.35 (d, J ¼ 8.0 Hz,
1H), 8.08e8.01 (m, 2H), 7.78e7.73 (m, 3H), 7.62e7.58 (m, 3H), 7.52
To a solution of (5-(4-(trifluoromethyl)phenyl)naphthalen-1-
yl)methanol (5.14.2) (40 mg, 0.13 mmol), PPh3 (55 mg,
0.21 mmol), and 1,3-bis(t-butoxycarbonyl)guanidine (70 mg,
0.27 mmol) in anhydrous toluene (3 mL) at 0 ꢁC was added
diisopropylazodicarboxylate (0.04 mL, 0.20 mmol) drop-wise
over 15 min. Reaction was stirred at RT overnight, and the
solution was then concentrated to an oil residue. Chromatog-
raphy using ISCO max gradient 30% EtOAc/hexane yielded
product as a white glassy residue (56 mg, 80% yield); 1H NMR
(d, J ¼ 8.0 Hz, 1H); 13C NMR (100 MHz) (CDCl3)
d 193.4, 144.1, 139.3,
136.6, 132.7, 131.7, 131.0, 130.5, 128.4, 128.0, 125.4, 125.3, 125.2,
125.1, 124.9, 120.3.
5.14.2. (5-(4-(Trifluoromethyl)phenyl)naphthalen-1-yl)methanol
A mixture of 5-(4-(trifluoromethyl)phenyl)-1-naphthaldehyde
(350 mg, 1.16 mmol) and NaBH4 (31 mg, 0.82 mmol) in 95%
EtOH/MeOH (15 mL) was stirred at RT for 1 h. Reaction was then
filtered and filtrate was concentrated. Residue was taken back up in
EtOAc and washed with saturated NaHCO3 solution followed by
brine. Organic layer was collected, dried over magnesium sulfate,
and concentrated. Chromatography using ISCO max gradient 30%
EtOAc/hexane yielded product as a white solid (350 mg, quantita-
(400 MHz) (CDCl3)
d
9.44 (bs, 2H), 8.00 (d, J ¼ 8.0 Hz, 1H), 7.67
(d, J ¼ 8.0 Hz, 2H), 7.61 (d, J ¼ 8.0 Hz, 1H), 7.53e7.48 (m, 3H),
7.35e7.28 (m, 2H), 7.12 (d, J ¼ 4.0 Hz, 1H), 5.68 (s, 2H), 1.37
(s, 9H), 1.12 (s, 9H); 13C NMR (100 MHz) (CDCl3)
d 163.8, 160.9,
155.1, 144.8, 139.4, 134.4, 131.4, 131.0, 130.5, 129.7, 126.8, 125.7,
125.6, 125.3, 125.2e125.1 (m), 124.6, 123.1, 122.1, 84.1, 79.0, 45.4,
28.2, 27.7; HRMS (ESI): calcd for C29H33F3N3O4 (M
544.2423, found 544.2431.
tive); mp 98 ꢁC; 1H NMR (400 MHz) (CDCl3)
1H), 7.79 (t, J ¼ 15.0, 3H), 7.66e7.58 (m, 4H), 7.48e7.43 (m, 2H), 5.22
(s, 2H); 13C NMR (100 MHz) (CDCl3)
144.7, 139.5, 136.7, 131.7e
d
8.23 (d, J ¼ 8.5 Hz,
þ
H)þ
d

406
C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
5.15.2. 2-((5-(4-(Trifluoromethyl)phenyl)naphthalen-1-yl)methyl)
guanidine (14)
anhydrous DCM (0.5 mL) and TFA (0.5 mL) overnight. Solvents were
then evaporated. Chromatography using ISCO max gradient 20% 3%
NH4OH/MeOH/DCM solution yielded product as a white solid (11 mg,
1,3-Di-Boc-2-((5-(4-(Trifluoromethyl)phenyl)naphthalen-1-yl)
methyl)guanidine (56 mg, 0.1 mmol) in a mixture of anhydrous
DCM (0.8 mL) and TFA (0.8 mL) was stirred at RT overnight. Solvents
were then evaporated. Chromatography using ISCO max gradient
20% 3% NH4OH/MeOH/DCM solution yielded product as a white
solid (20 mg, 51% yield); mp 198e200 ꢁC; 1H NMR (400 MHz)
85% yield); mp 240 ꢁC; 1H NMR (300 MHz) (CD3OD)
d 8.21
(d, J ¼ 6.0 Hz,1H), 7.84 (d, J ¼ 6.0 Hz, 2H), 7.73e7.64 (m, 4H), 7.51e7.43
(m, 3H), 3.66 (t, J ¼ 6.0 Hz, 2H), 3.46 (t, J ¼ 6.0 Hz, 2H); 13C NMR
(100 MHz) (CD3OD)
d 158.7, 146.4, 140.9, 135.9, 133.5, 133.1, 131.7,
128.4, 128.1, 127.1, 126.8, 126.3, 126.2, 126.1, 124.8, 124.5, 43.1, 33.2;
(CD3OD)
d
8.10 (d, J ¼ 8.6 Hz, 1H), 7.85e7.79 (m, 3H), 7.73e7.69 (m,
HRMS (ESI): calcd for C20H19F3N3 (M þ H)þ 358.1526, found 358.1535.
1H), 7.65 (d, J ¼ 8.0 Hz, 2H), 7.58e7.47 (m, 3H), 4.96 (s, 2H); 13C NMR
(100 MHz) (CD3OD)
d
158.9, 146.2, 141.0, 133.2, 133.1, 132.8, 131.8,
5.17. General procedure for the synthesis of compound (16)
130.9, 128.5, 127.4, 127.3, 127.0, 126.9, 126.4e126.3 (m), 124.5, 124.4,
44.6; HRMS (ESI): calcd for C19H17F3N3 (M þ H)þ 344.1369, found
344.1352.
5.17.1. (5-Bromonaphthalen-1-yl)methanol
To
a
solution of 5-bromo-1-naphthaldehyde (500 mg,
2.13 mmol) in EtOH (20 mL) was slowly added NaBH4 (243 mg,
6.39 mmol) and reaction was stirred at RT for 30 min. Acetone
(2 mL) was then added and solution was filtered through filter
paper. Filtrate was concentrated then re-dissolved in DCM and
washed with H2O. Organic layer was dried over sodium sulfate and
concentrated to yield pure product as a white solid (473 mg, 94%
5.16. General procedure for the synthesis of compound (15)
5.16.1. 1-(2-Nitrovinyl)-5-(4-(trifluoromethyl)phenyl)naphthalene
5-(4-(Trifluoromethyl)phenyl)-1-naphthaldehyde (200 mg,
0.67 mmol) and NH4OAc (60 mg, 0.78 mmol) in nitromethane
(3 mL) were heated to reflux for 6 h. Solvents were then evaporated.
Chromatography using ISCO max gradient 10% EtOAc/hexane yiel-
ded product as a yellow solid (210 mg, 91% yield); 1H NMR
yield); mp 100e101 ꢁC; 1H NMR (400 MHz) (CDCl3)
d 8.19e8.17 (m,
1H), 8.04 (d, J ¼ 8.0 Hz, 1H), 7.75e7.73 (m, 1H), 7.51e7.46 (m, 2H),
7.33e7.29 (m, 1H), 5.08 (d, J ¼ 8.0 Hz, 2H); 13C NMR (100 MHz)
(400 MHz) (CDCl3)
d
8.82 (d, J ¼ 13.4 Hz, 1H), 8.12 (d, J ¼ 8.6 Hz, 1H),
(CDCl3)
d 136.7, 132.6, 132.4, 130.1, 127.8, 126.8, 126.6, 126.2,
7.88 (d, J ¼ 8.6 Hz, 1H), 7.70 (d, J ¼ 7.9 Hz, 3H), 7.66e7.58 (m, 2H),
123.6, 63.6.
7.52 (d, J ¼ 8.0 Hz, 2H), 7.42e7.40 (m, 2H); 13C NMR (100 MHz)
(CDCl3)
d
143.9, 139.9, 138.9, 136.3, 131.9, 131.8, 130.4, 130.1, 127.9,
5.17.2. (5-(2-Methoxy-4-(trifluoromethyl)phenyl)naphthalen-1-yl)
methanol
127.6, 127.1, 126.5, 125.8, 125.4, 125.3, 123.3.
(5-Bromonaphthalen-1-yl)methanol (150 mg, 0.63 mmol),
5.16.2. 2-(5-(4-(Trifluoromethyl)phenyl)naphthalen-1-yl)
2-methoxy-4-trifluromethylphenylboronic
acid
(167
mg,
ethanamine
0.76 mmol), Pd(OAc)2 (14 mg, 0.063 mmol), XPhos (60 mg,
0.13 mmol), and K2CO3 (262 mg, 1.9 mmol) were combined in
a flask with dioxane (5 mL) and H2O (1.6 mL) and degassed. Reac-
tion mixture was then refluxed at 100 ꢁC for 2 h. Solution was
cooled to RT then diluted with EtOAc and washed with saturated
NaHCO3. Organic layer was dried over sodium sulfate and
concentrated. Chromatography using ISCO max gradient 35%
EtOAc/hexane yielded product as a clear oil (180 mg, 86% yield); 1H
LAH (1.0M/THF, 2 mL) was added drop-wise to a cooled 0 ꢁC
solution of 1-(2-nitrovinyl)-5-(4-(trifluoromethyl)phenyl)naph-
thalene (210 mg, 0.62 mmol) in anhydrous THF (10 mL). The
resultant mixture was then refluxed for 7 h. Reaction was cooled to
0 ꢁC and carefully treated with aqueous NaOH solution and diluted
with EtOAc. Solids were filtered off and filtrate washed with 6 N HCl
to extract out amine. 6 N HCl solution was then basified with 4 N
NaOH solution back to pH 9 and extracted with CHCl3. Organic layer
was then washed with brine, collected, dried over magnesium
sulfate, and concentrated yielded product as a pale solid requiring
no further purification (50 mg, 26% yield); 1H NMR (300 MHz)
NMR (400 MHz) (CDCl3)
d
8.24e8.22 (m, 1H), 7.64 (dd, J ¼ 8.0 Hz,
J ¼ 8.0 Hz, 1H), 7.55 (d, J ¼ 8.0 Hz, 1H), 7.51 (d, J ¼ 8.0 Hz, 1H), 7.45e
7.37 (m, 4H), 7.29 (s, 1H), 5.22 (s, 2H), 3.76 (s, 3H); 13C NMR
(100 MHz) (CDCl3)
d 157.5, 136.5, 136.3, 133.5, 132.2, 132.2, 131.5,
(CDCl3)
d
8.16 (d, J ¼ 9.0 Hz, 1H), 7.80e7.71 (m, 3H), 7.63e7.57 (m,
131.3,131.2,127.3,126.6,125.8,125.5e125.4 (m),123.9,122.8,117.5e
117.4 (m), 107.7, 66.0, 55.8; HRMS (ESI): calcd for C19H15F3NaO2
(M þ Na)þ 355.0916, found 355.0919.
3H), 7.44e7.37 (m, 3H), 3.36 (m, 2H), 3.23 (m, 2H).
5.16.3. 1,3-Di-Boc-2-(2-(5-(4-(trifluoromethyl)phenyl)naphthalen-
1-yl)ethyl)guanidine
5.17.3. 2-(5-(2-Methoxy-4-(trifluoromethyl)phenyl)naphthalen-1-
2-(5-(4-(Trifluoromethyl)phenyl)naphthalen-1-yl)ethanamine
(25 mg, 0.08 mmol), 1,3-di-Boc-2-(trifluoromethylsulfonyl)-guani-
dine (40 mg, 0.1 mmol), and Et3N (0.03 mL, 0.22 mmol) in anhy-
drous DCM (6 mL) were stirred at RT overnight. Solvents were then
evaporated. Chromatography using ISCO max gradient 30% EtOAc/
hexane yielded product as a white solid (20 mg, 44% yield); mp
yl)acetonitrile
To
a solution of (5-(2-methoxy-4-(trifluoromethyl)phenyl)
naphthalen-1-yl)methanol (180 mg, 0.54 mmol) and Et3N (0.15 mL,
1.08 mmol) in DCM (5 mL) was added MsCl (0.06 mL, 0.81 mmol),
and the reaction mixture was stirred at RT overnight. Reaction was
then diluted with DCM and washed with saturated NaHCO3.
Organic layer was dried over sodium sulfate and concentrated
without further purification. This crude (5-(2-methoxy-4-(tri-
fluoromethyl)phenyl)naphthalen-1-yl)methyl methanesulfonate
(150 mg, 0.37 mmol) was combined with KCN (48 mg, 0.73 mmol)
in anhydrous DMF (3 mL) and stirred at RT overnight. Reaction
mixture was then diluted with EtOAc and washed with 10% LiCl
solution. Organic layer was dried over sodium sulfate and
concentrated. Chromatography using ISCO max gradient 30%
EtOAc/hexane yielded product as clear oil (125 mg, 68% yield over
134e137 ꢁC; 1H NMR (300 MHz) (CDCl3)
7.60 (m, 6H), 7.44e7.35 (m, 3H), 3.81 (m, 2H), 3.44 (t, J ¼ 6.0 Hz, 2H),
1.56 (s, 9H), 1.50 (s, 9H); 13C NMR (100 MHz) (CDCl3)
163.7, 156.2,
d 8.50e8.40 (m, 1H), 7.78e
d
153.2, 144.9, 139.4, 135.2, 132.4, 131.8, 130.5, 131.8, 127.0, 126.9,
125.9, 125.7, 125.5, 125.2e125.1 (m), 124.9, 124.5, 83.1, 79.1, 41.8,
33.0, 28.4, 28.1; HRMS (ESI): calcd for C30H35F3N3O4 (M þ H)þ
558.2580, found 558.2590.
5.16.4. 2-(2-(5-(4-(Trifluoromethyl)phenyl)naphthalen-1-yl)ethyl)
guanidine (15)
1,3-Di-Boc-2-(2-(5-(4-(trifluoromethyl)phenyl)naphthalen-1-yl)
ethyl)guanidine (20 mg, 0.036 mmol) was stirred at RT in a mixture of
two steps); 1H NMR (400 MHz) (CDCl3)
d
7.97 (d, J ¼ 12.0 Hz, 1H),
7.72e7.68 (m, 1H), 7.63 (d, J ¼ 8.0 Hz, 1H), 7.56 (d, J ¼ 8.0 Hz, 1H),
7.47 (d, J ¼ 4.0 Hz, 1H), 7.44e7.40 (m, 3H), 7.30 (s, 1H), 4.21 (s, 2H),

C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
407
3.77 (s, 3H); 13C NMR (100 MHz) (CDCl3)
132.2, 130.9, 127.8, 127.2, 126.6, 126.5, 126.1, 125.5, 122.6, 117.7, 117.5,
117.4, 107.8, 107.7, 55.8, 22.0; HRMS (ESI): calcd for C20H14F3NO
(M)þ 341.1022, found 341.1019.
d
157.4, 136.8, 133.0, 132.2,
5.19.2. 1,3,-Di-Boc-2-((5-(2-methoxy-4-(trifluoromethyl)phenyl)
naphthalen-1-yl)methyl)guanidine
1,3-Di-Boc-2-((5-bromonaphthalen-1-yl)methyl)guanidine
(100 mg, 0.21 mmol), 2-methoxy-4-trifluromethylphenylboronic
acid (55 mg, 0.252 mmol), Pd(OAc)2 (5 mg, 0.021 mmol), XPhos
(20 mg, 0.042 mmol), and K2CO3 (87 mg, 0.63 mmol) were
combined in a flask with dioxane (3 mL) and H2O (1 mL) and
degassed. Reaction mixture was then refluxed at 100 ꢁC for 2 h.
Solution was cooled to RT then diluted with EtOAc and washed with
saturated NaHCO3. Organic layer was dried over sodium sulfate and
concentrated. Chromatography using ISCO max gradient 15%
EtOAc/hexane yielded product as a clear oil (55 mg, 46% yield); 1H
5.17.4. 2-(5-(2-Methoxy-4-(trifluoromethyl)phenyl)naphthalen-1-
yl)ethanamine (16)
A flask was charged with LAH (15.6 mg, 0.41 mmol) in anhy-
drous ether (3 mL). To the suspension was added 2-(5-(2-methoxy-
4-(trifluoromethyl)phenyl)naphthalen-1-yl)acetonitrile (70 mg,
0.21 mmol) in anhydrous ether (2 mL) drop-wise. Reaction was
stirred at RT for 30 min then placed on an ice bath. H2O (10 drops)
was carefully added in to quench remaining LAH then 1 M NaOH
was added to increase pH > 9. Solution was then diluted with
additional ether and organic layer was extracted from aqueous
layer. Organic layer was dried over sodium sulfate and concen-
trated. Chromatography using ISCO max gradient 10% MeOH/DCM
yielded product as clear oil (31 mg, 44% yield); 1H NMR (400 MHz)
NMR (400 MHz) (CDCl3)
d 9.55 (bs, 1H), 9.48 (bs, 1H), 8.08
(d, J ¼ 8.4 Hz, 1H), 7.61e7.57 (m, 1H), 7.42e7.33 (m, 5H), 7.27 (s, 1H),
7.19 (d, J ¼ 4.0 Hz, 1H), 5.86e5.70 (m, 2H), 3.75 (s, 3H), 1.47 (s, 9H),
1.21 (s, 9H); 13C NMR (100 MHz) (CDCl3)
d 163.8, 160.9, 157.4, 155.1,
136.2, 134.7, 132.2, 131.9, 127.0, 125.3, 125.0, 123.0, 121.9, 84.0, 79.0,
55.8, 45.4, 28.3, 27.6; HRMS (ESI): calcd for C30H35F3N3O5 (M þ H)þ
574.2523, found 574.2541.
(CDCl3)
6H), 7.28 (s, 1H), 3.77 (s, 3H), 3.33e3.29 (m, 2H), 3.19 (t, J ¼ 12.0 Hz,
2H); 13C NMR (100 MHz) (CDCl3)
157.5, 136.3, 135.9, 133.7, 132.3,
d
8.15 (d, J ¼ 8.0 Hz, 1H), 7.62e7.58 (m, 1H), 7.43e7.32 (m,
d
5.19.3. 2-((5-(2-methoxy-4-(trifluoromethyl)phenyl)naphthalen-1-
yl)methyl)guanidine (18)
132.2,132.0, 127.0, 126.8, 125.5,125.2, 125.0, 123.9, 117.4, 117.3, 107.7,
55.8, 42.9, 37.5; HRMS (ESI): calcd for C20H19F3NO (M þ H)þ
346.1413, found 346.1415.
To a cooled solution of 1,3-di-Boc-2-((5-(2-methoxy-4-(tri-
fluoromethyl)phenyl)naphthalen-1-yl)methyl)guanidine (55 mg,
0.1 mmol) in anhydrous DCM (1.5 mL) was added TFA (1.5 mL).
Reaction was taken off ice bath and stirred at RT for 2 h then
solvents were evaporated. Chromatography using ISCO max
gradient 10% MeOH/DCM yielded product as a tan gummy solid
5.18. General procedure for the synthesis of 2-(5-(2-aminoethyl)
naphthalen-1-yl)-5-(trifluoromethyl)phenol (17)
(31 mg, 86% yield); 1H NMR (400 MHz) (CD3OD)
1H), 7.59e7.55 (m, 1H), 7.43e7.36 (m, 2H), 7.34e7.28 (m, 5H), 4.84e
4.82 (m, 2H), 3.62 (s, 3H); 13C NMR (100 MHz) (CD3OD)
159.1,
d
7.96 (d, J ¼ 8.0 Hz,
To a cooled solution of 2-(5-(2-methoxy-4-(trifluoromethyl)
phenyl)naphthalen-1-yl)ethanamine (28 mg, 0.081 mmol) in
anhydrous DCM (4 mL) was added BBr3 (1.0 M in DCM, 0.41 mL)
drop-wise. The solution was then stirred at RT for 3 h and reaction
was placed back over ice. H2O was slowly dripped into the flask to
quench the remaining BBr3 and mixture was then diluted with
additional DCM and washed with NaHCO3. Organic layer was dried
over sodium sulfate and concentrated. Chromatography using ISCO
max gradient 10% MeOH/DCM to yield product as a clear oil (13 mg,
d
158.8, 138.1, 135.0, 133.7, 133.2, 132.9, 132.4, 128.6, 128.0, 127.3,
127.0, 126.8, 126.5, 124.1, 118.5, 118.4, 108.9, 56.3, 44.8; HRMS (ESI):
calcd for C20H19F3N3O (M þ H)þ 374.1475, found 374.1470.
5.20. General procedure for the synthesis of compound (19)
5.20.1. 1,3-Di-Boc-2-(2-(5-(2-methoxy-4-(trifluoromethyl)phenyl)
naphthalen-1-yl)ethyl)guanidine
48% yield); 1H NMR (400 MHz) (CD3OD)
d
8.05 (d, J ¼ 8.0 Hz, 1H),
7.48 (dd, J ¼ 8.0 Hz, J ¼ 8.0 Hz, 1H), 7.35 (d, J ¼ 8.0 Hz,1H), 7.29e7.26
(m, 2H), 7.24e7.20 (m, 2H), 7.12e7.10 (m, 2H), 3.20 (t, J ¼ 12.0 Hz,
2-(5-(2-Methoxy-4-(trifluoromethyl)phenyl)naphthalen-1-yl)
ethanamine
(25
mg,
0.073
mmol),
1,3-di-Boc-2-(tri-
2H), 2.96 (t, J ¼ 12.0 Hz, 2H); 13C NMR (100 MHz) (CD3OD)
d
157.0,
fluoromethylsulfonyl)-guanidine (34 mg, 0.087 mmol), and Et3N
(0.01 mL, 0.087 mmol) in anhydrous DCM (2.5 mL) were stirred at
RT overnight. Reaction mixture was then diluted with DCM and
washed with NaHCO3. Organic layer was dried over sodium sulfate
and concentrated. Chromatography using ISCO max gradient 30%
EtOAc/hexane yielded product as a clear oil (37 mg, 88% yield); 1H
138.1, 136.5, 133.8, 133.6, 133.5, 133.4, 132.3, 132.0, 128.3, 127.9,
127.0, 126.6, 126.4, 124.8, 116.8, 113.4e113.3 (m), 43.2, 36.5; HRMS
(ESI): calcd for C19H17F3NO (M þ H)þ 332.1257, found 332.1259.
5.19. General procedure for the synthesis of compound (18)
NMR (400 MHz) (CDCl3)
d
11.50 (bs, 1H), 8.50 (bt, J ¼ 12.0 Hz, 1H),
8.38 (d, J ¼ 8.0 Hz,1H), 7.62 (dd, J ¼ 8.0 Hz, J ¼ 8.0 Hz,1H), 7.43e7.36
(m, 5H), 7.35e7.31 (m, 1H), 7.27 (s, 1H), 3.85e3.79 (m, 2H), 3.76 (s,
3H), 3.50e3.37 (m, 2H),1.57 (s, 9H),1.51 (s, 9H); 13C NMR (100 MHz)
5.19.1. 1,3-Di-Boc-2-((5-bromonaphthalen-1-yl)methyl)guanidine
(5-Bromonaphthalen-1-yl)methanol
(5.17.1)
(275
mg,
1.16 mmol), PPh3 (456 mg, 1.74 mmol), and 1,3-bis(t-butox-
ycarbonyl)guanidine (601 mg, 2.32 mmol) in anhydrous toluene
(5 mL) at 0 ꢁC was added diisopropylazodicarboxylate (0.34 mL,
1.74 mmol) drop-wise over 15 min. Reaction was stirred for 3 h at
RT then 2 drops H2O were added, and the solution was concen-
trated. Chromatography using ISCO max gradient 20% EtOAc/
hexane yielded product as a white solid (493 mg, 90% yield); mp
(CDCl3) d 163.7, 157.5, 156.1, 153.2, 136.2, 135.0, 133.8, 132.2, 132.1,
127.1, 126.8, 125.5, 125.4, 125.3, 124.3, 117.3, 83.0, 79.1, 55.8, 41.8,
33.0, 28.4, 28.1; HRMS (ESI): calcd for C31H37F3N3O5 (M þ H)þ
588.2680, found 588.2698.
5.20.2. 2-(2-(5-(2-Methoxy-4-(trifluoromethyl)phenyl)naphthalen-
1-yl)ethyl)guanidine (19)
164e165 ꢁC; 1H NMR (400 MHz) (CDCl3)
d
9.47 (bs, 2H), 8.11
To a cooled solution of 1,3-di-Boc-2-(2-(5-(2-methoxy-4-(tri-
fluoromethyl)phenyl)naphthalen-1-yl)ethyl)guanidine (35 mg,
0.06 mmol) in anhydrous DCM (1 mL) was added TFA (1 mL).
Reaction was taken off ice bath and stirred at RT for 2 h then
solvents were evaporated. Chromatography using ISCO max
gradient 10% MeOH/DCM yielded product as a clear oil (19 mg, 83%
(d, J ¼ 8.0 Hz,1H), 7.91 (d, J ¼ 8.0 Hz,1H), 7.73 (d, J ¼ 8.0 Hz,1H), 7.46
(t, J ¼ 16.0 Hz, 1H), 7.28 (t, J ¼ 16.0 Hz, 1H), 7.16 (d, J ¼ 8.0 Hz, 1H),
5.62 (s, 2H), 1.36 (s, 9H), 1.07 (s, 9H); 13C NMR (100 MHz) (CDCl3)
d
160.8, 155.0, 135.0, 132.0, 129.9, 126.7, 126.3, 126.2, 123.7, 122.9,
122.7, 84.2, 79.0, 45.1, 28.2, 27.6; HRMS (ESI): calcd for
C22H29BrN3O4 (M þ H)þ 478.1336, found 478.1344.
yield); 1H NMR (400 MHz) (CD3OD)
d
8.16 (d, J ¼ 8.6 Hz, 1H), 7.66e

408
C. Kelley et al. / European Journal of Medicinal Chemistry 60 (2013) 395e409
7.62 (m, 1H), 7.44e7.34 (m, 7H), 3.74 (s, 3H), 3.65 (t, J ¼ 16.0 Hz, 2H),
3.46e3.42 (m, 2H); 13C NMR (100 MHz) (CD3OD)
159.1, 158.7,
138.0, 135.5, 135.3, 133.7, 133.3, 133.2, 128.3, 128.1, 127.0, 126.8,
126.7, 126.6, 124.5, 118.4, 118.3, 108.8, 56.2, 43.2, 33.1; HRMS (ESI):
calcd for C21H21F3N3O (M þ H)þ 388.1631, found 388.1630.
assay kit (Bio-Rad) and bovine serum albumin as the standard. The
final FtsZ concentration was w8 mg/mL and the protein was w90%
pure as determined by SDS-PAGE analysis.
d
5.23. FtsZ polymerization assays
5.21. Minimum inhibitory concentration (MIC) assays
Polymerization of SaFtsZ was monitored using a microtiter
plate-based turbidity assay. Experiments were conducted at 25 ꢁC
in solution containing 50 mM Tris$HCl (pH 7.4), 50 mM KCl, 2 mM
magnesium acetate and 1 mM GTP. GTP was combined with vehicle,
compound, or control drug and the reactions were initiated by
MIC assays were conducted in accordance with Clinical Labo-
ratory Standards Institute (CLSI) guidelines for broth microdilution
[26]. The following bacterial strains were included in these assays:
S. aureus 8325-4 (MSSA); S. aureus ATCC 33591 (MRSA); E. faecalis
ATCC 19433 (VSE) and; E. faecalis ATCC 51575 (VRE). Log-phase
bacteria were added to 96-well microtiter plates (at 105 CFU/mL)
containing 2-fold serial dilutions of compound or comparator
addition of the protein at a final concentration of 10
mM. The
reactions (100 L total volume) were assembled in half-volume,
m
flat-bottom 96-well microtiter plates and their absorbances at
340 nm were continuously monitored using a VersaMaxÒ plate
reader over a time period of 300 min.
drug (at concentrations ranging from 64 to 0.031
mg/mL) in
cation-adjusted Mueller-Hinton (CAMH) broth (for the S. aureus
assays) or brain-heart infusion (BHI) broth (for the E. faecalis
assays). In the MRSA assays, the CAMH broth was supplemented
with 2% NaCl. The final volume in each well was 0.1 mL and the
microtiter plates were incubated aerobically for 24 h at 37 ꢁC.
Bacterial growth was then monitored by measuring OD600 using
a VersaMaxÒ plate reader (Molecular Devices, Inc.), with the MIC
being defined as the lowest compound concentration at which
growth was ꢂ90% inhibited.
Acknowledgments
This study was supported by research agreements between
TAXIS Pharmaceuticals, Inc. and both Rutgers, The State University
of New Jersey (E.J.L.) and the University of Medicine and Dentistry
of New Jersey (D.S.P). We would like to thank Drs. Steve Tuske and
Eddy Arnold (Center for Advanced Biotechnology and Medicine,
Rutgers University) for their assistance with the expression and
purification of S. aureus FtsZ protein. We also appreciate the
editorial review by Greg Mario. S. aureus 8325-4 was the generous
gift of Dr. Glenn W. Kaatz (John D. Dingell VA Medical Center,
Detroit, MI). The Brucker Avance III 400 MHz NMR spectrometer
used in this study was purchased with funds from NCRR Grant No.
1S10RR23698-1A1. Mass spectrometry was provided by the
Washington University Mass Spectrometry Resource with support
from the NIH National Center for Research Resources Grant No.
P41RR0954.
5.22. Expression and purification of S. aureus FtsZ (SaFtsZ)
The FtsZ gene from S. aureus was amplified by polymerase chain
reaction (PCR) from the S. aureus genome obtained from ATCC
(ATCC 33591-D). The amplified gene product was then ligated into
the pET-22b(þ) cloning vector (Novagen-EMD Chemicals, Inc.),
with the sequence of the final recombinant plasmid (pETSAFtsZ)
being verified by sequence analysis and used to transform E. coli
BL21 (DE3) cells.
A single colony of pETSAFtsZ-transformed E. coli cells was used
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