Two-Photon Excitable Photoremovable Protecting Groups Based on the Quinoline Scaffold for Use in Biology

Article abstract of DOI:10.1021/acs.joc.9b02780

Photoremovable protecting groups (PPGs) are powerful tools for physiological studies, harnessing light as an on/off switch to provide tight spatio-temporal control over the release of biological effectors through two-photon excitation (2PE) in tissue culture and whole-animal studies. We carried out a series of systematic structural modifications to the (8-cyano-7-hydroxyquinolin-2-yl)methyl (CyHQ) chromophore to conduct an SAR study with the aim of enhancing its photochemical properties, especially its two-photon uncaging action cross section (δ_u). The best results were obtained when substituents were added at the C4 position, which improved δ_u for release of acetate up to 7-fold, while retaining all the other excellent properties of the CyHQ PPG, including high quantum yield (φ_u), low susceptibility to spontaneous hydrolysis in the dark, and good aqueous solubility. Hammett correlation analysis suggested that photolysis efficiency is favored by electron-rich substituents at C4, giving important insights into the mechanism of the photolysis reaction. The four best CyHQ derivatives were used to mediate the efficient release of homopiperonylic acid in high yield under simulated physiological conditions. Our efforts have led to the development of 2PE-sensitive PPGs with remarkable δ_u values (up to 2.64 GM), excellent quantum yields (up to 0.88), and high-yielding effector release (up to 92%).

Full text of DOI:10.1021/acs.joc.9b02780

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Article
Two-Photon Excitable Photoremovable Protecting Groups
Based on the Quinoline Scaffold for Use in Biology
Anna-Lisa K. Hennig, Davide Deodato, Naeem Asad, Cyril Herbivo, and Timothy M. Dore
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.9b02780 • Publication Date (Web): 06 Dec 2019
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Two-Photon Excitable Photoremovable Protecting Groups Based on the
Quinoline Scaffold for Use in Biology
Anna-Lisa K. Hennig,†,§ Davide Deodato,†,§ Naeem Asad,†,§ Cyril Herbivo, and Timothy M. Dore*
†
,†,‡
†
New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates
Department of Chemistry, University of Georgia, Athens, GA 30602, USA
‡
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§These authors contributed equally.
ABSTRACT
Photoremovable protecting groups (PPGs) are powerful tools for physiological studies, harnessing light as an
on/off switch to provide tight spatio-temporal control over the release of biological effectors through two-
photon excitation (2PE) in tissue culture and whole-animal studies. We carried out a series of systematic
structural modifications to the (8-cyano-7-hydroxyquinolin-2-yl)methyl (CyHQ) chromophore to conduct an
SAR study with the aim of enhancing its photochemical properties, especially its two-photon uncaging action
cross-section (d
improved d for release of acetate up to 7-fold, while retaining all the other excellent properties of the CyHQ
PPG, including high quantum yield (F ), low susceptibility to spontaneous hydrolysis in the dark, and good
u
). The best results were obtained when substituents were added at the C4 position, which
u
u
aqueous solubility. Hammett correlation analysis suggested that photolysis efficiency is favored by electron-rich
substituents at C4, giving important insights into the mechanism of the photolysis reaction. The four best CyHQ
derivatives were used to mediate the efficient release of homopiperonylic acid in high yield under simulated
physiological conditions. Our efforts have led to the development of 2PE-sensitive PPGs with remarkable d
u
values (up to 2.64 GM), excellent quantum yields (up to 0.88), and high-yielding effector release (up to 92%).
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INTRODUCTION
In recent years, therapeutic agents and biologically active molecules have been increasingly employed to
study biological systems and understand the physiological processes involved therein. Nevertheless, these
probes can have unwanted side effects and reactions caused by activation of off-target receptors resulting from
the systemic application of and poor control over the diffusion of an agent in a tissue preparation. To address
this issue, there is a need to develop new tools that can turn “OFF” the biological activity of these molecules
during administration and delivery to the desired location within the biological sample and turn it back “ON”
with an external stimulus. Light (especially in the IR region) is an ideal exogenous, non-chemical stimulus that
can be employed to turn on the bioactivity, while causing negligible harm to the biological system. In this
regard, light-sensitive probes such as photoremovable protecting groups (PPGs)1-3 are extremely powerful tools
for studying physiological processes. PPGs (also referred to as “caging” groups or phototriggers) are useful
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because of their ability to render a bioactive agent inactive by masking its biological function, while being
simple to use. They offer the means of delivering bioactive molecules such as neurotransmitters,4,5 Ca
2+ 6
second
,
7
messengers, etc., to small addressable targets and enable experiments that follow physiological events in real
time. These tools have proven useful for studying physiological processes in cell cultures,8,9 tissues,10,11 and
whole animals.12,13
For use in biological systems, “good caging groups” possess several atributes:1-3 (i) optimal solubility at
physiological pH; (ii) rapid release kinetics; (iii) high quantum yields (F ) of the photolysis reaction; (iv)
u
stability to hydrolysis in the dark; (v) low or no toxicity of the PPG and its photoproducts; and (vi) good
absorption at long wavelengths to avoid photodamage, allow deeper tissue penetration, and minimize the
undesirable photochemical reactions that occur at high-energy wavelengths. Over the last 30 years, the library of
biologically useful PPGs has significantly increased and many of those currently employed satisfy most of the
aforementioned conditions. Nevertheless, there is still a void in the development of PPGs that can efficiently
release the active component through excitation in IR region. Any PPGs that have been designed to absorb near-
IR light tend to suffer from various limitations, such as inefficient photolysis, lower excited state energy, or
limited solubility in the case of extended chromophores.14,15 Two-photon excitation (2PE) is an attractive
16
method for releasing PPGs at longer wavelengths. This photophysical phenomenon, first described
17
theoretically by Maria Göppert-Mayer, occurs when two photons are absorbed simultaneously by the
chromophore and exciting it, which triggers a photolysis reaction. The efficiency of a PPG toward 2PE is
defined by the two-photon uncaging action cross-section (d ), expressed in Göppert-Mayer (GM) and described
u
by the following equation:
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(
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d
u
= d
a
F
u
where d
a
is the two-photon absorbance cross-section and F is the quantum yield of the photochemical reaction.
u
Photochemistry driven by 2PE not only provides precise temporal control, but is also highly localized,
conferring much better spatial control by releasing the biological effector in femtoliter-sized volumes at the
focal point of the laser beam.18,19 This strategy affords a red-shifting of the light-induced photorelease into the
therapeutic window (∼650–950 nm) resulting in deeper tissue penetration, reduced photodamage to the
biological system, and enhanced 3-dimensional resolution of biological effector activation.
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It is evident that 2PE-sensitive PPGs have numerous differences than those excited by traditional one-
photon excitation (1PE). Nevertheless, chromophores with adequate properties for use in biology are extremely
rare, with most of those that exist exhibiting low sensitivity to 2PE (d
biological incompatibility (low aqueous solubility, poor cellular uptake, and toxicity)10,20-26 (Figure 1). Based on
bleaching experiments and diffusion rates, a d value of nearly 4 GM is required to achieve a large, steady-state
concentration of activated effector within the focal volume of the laser. Coumarin-based PPGs represent the
most successful example to date, possessing high d
values (> 1 GM) and fast kinetics.19,28,29 Coumarin PPGs,
u
< 1 GM), slow photorelease kinetics, or
u
2
7
u
however, display a high level of fluorescence upon excitation, which particularly limits their applicability when
fluorescent indicators are used to observe the physiological event, as is common. Thus, there is a need to
develop PPGs with better 2PE properties that can be used in experiments that require precise timing and
location of photoactivation in tissue culture, ex vivo organs, and whole animals.
OMe
O
MeO
LG
NO2
MeO
MeO
R
O
R
LG
NO2
DMNB
LG
LG
N
LG
HO
OH
NO2
LG
NO2
R
PMNB
NDBF
MNI
DHC
R
LG
O
COOH
COOH
Br
LG
N
H
R1
N
LG
HO
N
R2
HO
O
O
Et N
2
O
O
CN
BHQ: R = OH, R = Br
CyHQ: R = OH, R = CN
-DMAQ: R = NMe , R = H
-DMAQ: R = H, R = NMe
2
1
2
1
2
Bhc
DEAC450
C4-substituted CyHQ
7
8
1 2 2
1
2
Figure 1. Examples of PPGs photolyzed through two-photon excitation. LG, Leaving Group.
A promising direction toward the discovery of PPGs with improved sensitivity to 2PE without
compromising biological compatibility is to turn toward quinoline-based PPGs, which possess high photolysis
efficiencies, extremely fast release kinetics, excellent aqueous solubilities, low cellular toxicities, and are able to
release a wide variety of functional groups (carboxylic acids, phenols, aldehydes, diols, amines, and
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phosphates).18,30-34 These compounds also exhibit low levels of fluorescence, enabling them to be used alongside
fluorescent dyes.32,35 One drawback to quinoline-based PPGs is the low values of d
which limits their application in tissues or whole animal studies. A high d
quadrupolar structure in which a fluorene group was inserted between the C5-positions of two 8-
(generally < 0.6 GM),30,36,37
u
u
value (2.3 GM) was reported for a
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dimethylaminoquinoline (8-DMAQ, Figure 1) PPGs, but this value was measured in 1:1 acetonitrile/TRIS
buffer, which could never be used in a biological preparation. Furthermore, at 366 nm (1PE), a powerful 8-W
lamp required 1 to 5 hours to deplete 1 mL of a 0.1-mM solution (i.e., 100 µmol of substrate) of the PPG, and
the d measurements were conducted by exposing a 45-µL sample to 5 hours of 100-mW, 730-nm laser
u
irradiation without any evaporation of the solvent. These observations run counter to the argument that these
PPGs photolyze efficiently. A 5-para-carboxyphenyl substituent on 8-DMAQ resulted in a more water-soluble
PPG, and the authors reported d = 2.0 GM, but provided insufficient information on how the cross-section
u
measurement for the photolysis reaction was made.39
The (8-bromo- (BHQ) and (8-cyano-7-hydroxyquinolin-2-yl)methyl (CyHQ) PPGs (Figure 1), which have
3
0
d = 0.59 and 0.32 GM, respectively, for their corresponding protected acetates, represent interesting scaffolds
u
that have been used successfully for the photoactivation of biological effectors to study different physiological
processes.13,33,40-42 BHQ and CyHQ rapidly photolyze on the nanosecond timescale31,43,44 and 3 mL of a 0.1-mM
solution (i.e, 300 µmol of substrate) fully cleaves in approximately 2 min or less with 8-12 mW of 365-nm light
from an LED.31,45,46 In the present study, we introduced chemical modifications to these chromophores to
enhance the photochemical properties, especially the d values. Our efforts led to the identification of a set of
u
C4-substituted chromophores (Figure 1) that showed almost an order of magnitude increase in d , while
u
retaining the other excellent properties of the quinoline-based PPGs.
RESULTS AND DISCUSSION
Despite having a slightly higher cross-section, BHQ suffers a secondary photo-debromination reaction
4
3
when irradiated that limits its utility, and when we placed a phenyl group in the C4 position, debromination
was the exclusive product. For this reason, we chose CyHQ, a PPG with clean and robust photochemistry, as a
model compound for an optimization campaign. Acetate was selected as a model leaving group to simplify the
synthesis and for comparison with literature data.
The value of d
u
is affected by two parameters: d
a
and F
u
. Enhancing either parameter will increase d
u
.
Enhancing d of organic molecules has proved to be an extremely difficult challenge and has been the subject of
a
many review articles.16,47-50 General strategies include extending conjugation, adding planarity, introducing
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molecular symmetry or multibranched oligomers, or inserting strong donor/acceptor pairs. All these
modifications tend to require the introduction of multiple large, lipophilic, aromatic rings that negatively impact
the solubility of the chromophore. Alternatively, F depends on the rate constants of the bond reorganization
u
events happening after light absorption and can be significantly affected by small structural modifications that
have only a slight impact on chromophore solubility.
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Taking these considerations into account, we introduced point modifications on the CyHQ PPG with the
aim of increasing d
u
by modulating F
u
. We investigated the effects of a primary vs secondary carbon alpha to
) for
the leaving group, since this modification has been shown to increase the photolysis rate (and ultimately F
u
4
6
CyHQ-protected anilines. Six derivatives (1a-f), bearing substituents that would impart different electronic
and steric effects at the 2-methyl position, were designed and synthesized (Scheme 1). The secondary alcohols
used as starting materials (MOM-CyHQ-R-OH) were obtained through a Grignard reaction on the
corresponding aldehyde (MOM-CyHQ-CHO30,31), using a protocol described previously. The modified
CyHQ-protected acetates 1a-f were prepared by acetylation of the alcohols, followed by MOM-deprotection.
All compounds were isolated as racemic mixtures.
46
Scheme 1. Synthesis and photolysis reaction of 2-methyl substituted acetates 1a-f.
RMgBr
O
*
OH
MOMO
N
THF, 0 °C
MOMO
N
CN
MOM-CyHQ-CHO
CN
R
MOM-CyHQ-R-OH
1
. Ac O, DMAP, Py, CH Cl
2 2 2
*
OAc
HO
N
2
. TFA, CH Cl
2
2
CN
a: R = Me
1b: R = iPr
c: R = Ph
d: R = cyclopropyl
1e: R = CF3
f: R = allyl
R
30-87%
1
1
1
1
AcO
OH
hν
*
OAc
*
O
N
(365 or 740 nm)
KMOPS buffer
pH 7.2
O
N
CN
R
CN
R
1
a-f
2a-f
The photochemistry induced by 1PE and 2PE of the modified CyHQ-protected acetates 1a-f was
investigated by irradiating 0.1 mM solutions of each of them in simulated physiological buffer (potassium 3-
morpholinopropane-1-sulfonate (KMOPS), pH 7.2) with 365-nm light (1PE) from an LED or 740-nm light from
a Ti:sapphire laser (2PE). The photochemical reactions were sampled at different time intervals to monitor the
course of the photolysis reaction by HPLC (see Supporting Information for full details). The photochemical and
photophysical properties determined are shown in Table 1.
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Table 1. Photophysical and photochemical data for 2-methyl-substituted CyHQ-protected acetates.a
l
abs
e
365
1
Sensitivity
d
u
Compound
F
u
-
-1
b
(
nm)
(M cm )
(
e F
u
)
(GM)
0.32
0.29
0.35
c
CyHQ-OAc
364
362
362
365
363
367
345
7700
0.31
0.28
0.16
0.13
0.47
0.35
0.39
2387
1977
1600
1461
2773
2013
2048
1
1
a
7010
b
10000
11240
5900
d
1
c
n.p.
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d
0.19
0.14
0.06
1
e
5750
1
f
5250
a
b
-
0
.1 mM solution in KMOPS buffer, pH 7.2. GM = 10
50
4
c
30 d
cm s/photon. Taken from literature. No
photolysis.
These data showed no improvement in the 2PE-mediated photolysis reaction; the d values measured were
u
in most cases lower than those of the parent compound CyHQ-OAc, except for the isopropyl derivative 1b,
which showed a slightly higher value (0.35 GM). The cyclopropyl derivative 1d displayed improved 1PE
quantum yield and sensitivity (e·F ), a measure of the efficacy of a PPG at a given wavelength, but was less
u
sensitive to 2PE than CyHQ-OAc. Taken together, these results demonstrate that altering the electronic and
steric properties of the methyl group at the C2 position of the quinoline ring has no positive effect on the 2PE-
mediated photolysis of CyHQ-OAc.
The next modification was carried out on the C4 position to exploit the so-called “meta-effect” first
described by Zimmerman and coworkers.54-57 This effect arises from the selective transmission of electron
density to the meta position of an aromatic ring in the first excited state (in contrast to the ortho/para
transmission in the ground state), and has been shown to increase the rate of light-induced heterolysis of various
PPGs.58-60 Furthermore, adding chlorine to the 4-position of 7-DMAQ-OAc (a previously reported quinoline-
3
0
based PPG, Figure 1) improved its d
the photochemical properties of this family of PPGs. Several CyHQ-OAc derivatives with C4 modifications
were synthesized to investigate the influence of meta substitution on the d and F values. The effects of
u
by more than 3-fold, suggesting a positive impact of a 4-substituent on
u
u
electron withdrawing groups (chloro, cyano), electron donating groups (dimethyl amino, morpholino, methyl),
and aromatic (phenyl, pyrrole) substituents at C4 were explored. A series of derivatives with substituted phenyl
groups at the C4 position was also synthesized to modulate the electronics of the quinoline ring, and a 4-
ethynylbenzene derivative was prepared to extend the conjugation of the quinoline.
The synthesis of this new series of CyHQ-based PPGs required the preparation of the C4-activated
compounds 7 and 8, which were obtained according to a high-yielding pathway (Scheme 2). The synthesis
began with a condensation reaction between meta-anisidine and ethyl acetoacetate, and the corresponding imine
was then cyclized by refluxing with diphenyl ether to afford the 4-hydroxyquinoline 3. Chlorination with POCl
3
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yielded the 4-chloro derivative 4, which was then deprotected with HBr, resulting in the formation of 7-
hydroxyquinoline 5. Subsequent bromination with NBS afforded 8-bromo-7-hydroxyquinoline 6, which was
3
1
converted to the corresponding 8-cyano compound 7 using a previously described method. The protocol
involved protection of the phenol with an acetyl group, followed by subsequent cyanation with copper (I)
cyanide and further treatment with ammonium hydroxide solution to remove copper complexes. To facilitate the
subsequent Suzuki reaction, 4-iodo intermediate 8 was prepared from the chloride 7 by nucleophilic aromatic
substitution and subsequent MOM-protection.
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Scheme 2. Synthesis of common intermediates 7 and 8.
OH
O
O
1
2
.
OEt
POCl3
88%
. Ph O, reflux
NH2
2
MeO
60%
MeO
N
meta-anisidine
3
Cl
N
Cl
HBr
NBS
CH Cl
2
8
4%
2
MeO
HO
HO
N
98%
4
5
Cl
Cl
1
. TEA, AcCl, CH CN
3
2
3
. CuCN, DMAc
. 33% NH OH
N
HO
N
4
Br
CN
5
1%
6
7
I
1
. TFA, CH Cl
2 2
2
. NaI, CH CN
3
MOMO
N
3. MOM-Cl, TEA,CH Cl2
2
CN
8
89%
The key step toward the synthesis of the target 4-substituted CyHQ derivatives 9a-t was a Michael
addition or Suzuki or Sonogashira coupling at C4 of the 4-chloro and 4-iodo intermediates 7 and 8, respectively
(Scheme 3). The Michael addition reactions were performed on substrate 7 in refluxing N,N¢-dimethylacetamide
with the addition of the nucleophile (copper cyanide for 9b, dimethylamine generated by decomposition of the
solvent for 9c, or morpholine for 9d). A Sonogashira coupling reaction was used to prepare the phenylacetylene
derivative 9e from iodide 8. Suzuki coupling reactions on iodide 8 under typical conditions (boronic acid,
palladium acetate, and phosphine ligand in anhydrous dioxane) afforded 4-substituted compounds 9f-t in good
to high yields. (Scheme 3).
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1
1
1
1
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1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
Scheme 3. Synthesis of 4-substituted quinolines 9a-t.
Michaeal addition reactions
Cl
Cl
R
N
MOMCl, Et N
1. Nucleophile, Me NAc
2
3
CH Cl
2. MOMCl, Et N, CH Cl
2
3
2
2
2
MOMO
N
HO
N
MOMO
CN
CN
CN
9b: R = CN
9c: R = NMe2
9
a
7
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
O
9
d: R =
N
Suzuki and Sonogashira reactions
R
I
R-PhB(OH)2
Pd(OAc)
RuPhos, Cs CO3
phenylacetylene
2
Pd(OAc) , CuI
2
2
MOMO
N
Et N, dioxane
dioxane
3
CN
MOMO
N
MOMO
N
8
NTIPS
CN
2
CN
ioxane
B(OH)2
9
e
9h: R = H
9i: R = 4 Me
9j: R = 4-OMe
k: R = 4-CN
9o: R = 3-Me
9p: R = 3-OMe
9q: R = 3-F
, d
Pd(OAc)
3
2CO
,
Pd(OAc) , RuPhos
-
2
2
Cs CO , dioxane
2
3
9
9r: R = 3-NMe2
MeB(OH)
RuPhos, Cs
9l: R = 4-CO t-Bu 9s: R = 3,5-(OMe)2
NTIPS
2
9
m: R = 4-F
n: R = 4-NMe2
9t: R = 3,4,5-(OMe)3
Me
N
9
MOMO
MOMO
N
CN
CN
9g
9
f
The pathway leading to 4-substituted CyHQ-protected acetates 12a-v began with a Riley oxidation
reaction of 9a-t, followed by reduction of the intermediate aromatic aldehydes with NaBH , to yield benzylic
4
alcohols 10a-v. During the first step of the process, the two dimethylaminophenyl derivatives 9n and 9r
partially underwent an over-oxidation reaction generating, together with the expected derivatives 10n and 10r,
the N-formylated products 10u and 10v, which were isolated and carried forward separately (Scheme 4). The
acetate leaving group was added by acetylation followed by deprotection of the MOM group with TFA,
affording the 4-substituted CyHQ-protected acetates 12a-v. For the 4-pyrrole derivative 12g, an additional step
was necessary: treatment with tetra-butyl ammonium fluoride solution to cleave the triisopropylsilyl protecting
group (Scheme 4).
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Scheme 4. Synthesis of 4-substituted CyHQ-protected acetates 12a-v.
R
R
1. SeO2
t-BuOOH
dioxane
OH
MOMO
N
MOMO
N
CN
a-t
2. NaBH
4
, EtOH
CN
10a-v
9
11-84%
R
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Ac O
A: TFA, CH Cl , 45-99%
2 2
2
DMAP, Py
OAc B: 1. TBAF, THF
MOMO
N
CH Cl2
2. TFA, CH
2 2
Cl
2
CN
11a-v
21-96%
65%
a: R = Cl
h: R = Ph
i: R = 4-MePh
j: R = 4-MeOPh
k: R = 4-NCPh
R
b: R = CN
c: R = NMe2
O
OAc d: R =
l: R = 4-HO CPh
m: R = 4-FPh
2
HO
N
N
CN
e: R =
n: R = 4-Me NPh
2
o: R = 3-MePh
p: R = 3-MeOPh
q: R = 3-FPh
1
2a-v
f: R = Me
g: R =
NH
r: R = 3-Me NPh
2
s: R = 3,5-(MeO) Ph
2
via path B
t: R = 3,4,5-(MeO) Ph
3
u: R = 4-Me(CHO)NPh
v: R = 3-Me(CHO)NPh
The photolysis reactions proceeded cleanly, generating alcohols 13a-v and released acetate as the only
photoproducts (Figure 2). The time-course for each photolysis reaction (through 1PE or 2PE) was monitored by
HPLC (selected examples are shown in Figure 3; all of the time-courses are reported in the Supporting
Information). At 365 nm (1PE), the reactions are extremely fast since in most cases the starting material is
completely consumed within a minute of irradiation. The time-courses of the photolysis at 740 nm (2PE) are, as
expected, considerably slower due to the small illumination volume, but we could reach up to 25% consumption
of starting material within 30 min of irradiation (250-350 mW average laser power) for compound 12i. From
could be calculated as previously described (Table 2).28,30,31,45 The average
these curves, values of d
power used to measure d
order to detect changes to the concentration of the starting material and products by HPLC in a reasonable
u
and F
u
u
is larger than what would be used in biological studies on a microscope (< 10 mW) in
amount of time, because the laser focal volume is smaller than the sample volume. The value of d measured
u
with this technique does not depend on the average laser power.
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1
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1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
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4
4
4
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5
5
5
5
5
5
5
5
5
6
R
R
AcO
hν
OAc (365 or 740 nm)
KMOPS buffer
pH 7.2
OH
O
N
O
N
CN
CN
1
2a-v
13a-v
ꢀ
ꢁꢂ
hv
6
0 s
0
1
2
3
4
5
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9
0
1
2
3
4
5
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7
8
9
0
1
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9
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9
0
1
2
3
4
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7
8
9
0
hv
1
0 s
ꢀꢀꢀ
1
ꢀꢀ
dark
0
2
4
6
8
Retention time (min)
Figure 2. Photolysis of 4-substituted CyHQ acetates. (top) Photochemical reaction. (bottom) HPLC traces for
the photolysis of 12t at 365 nm (LED source, 1PE) at different time intervals. Absorbance was monitored at 320
nm.
1
00
1
1
1
2c
2d
2f
80
12i
6
4
0
0
12s
20
0
-0
100
50
100
Time (s)
150
200
8
6
4
2
0
0
0
0
0
12c
1
1
1
2d
2f
2i
12s
10
-0
20
30
40
50
60
Time (min)
Figure 3. Time courses for the photolyses of 12c,d,f,i,s mediated by (top) 1PE (LED, 365 nm) and (bottom)
2PE (Ti:sapphire laser, 740 nm). Percentage remaining was determined by HPLC analysis and is the average of
three runs. Lines are least-squares fits of the data to a simple exponential decay. All fits for the photolyses via
2PE approach zero asymptotically. Error bars represent the standard deviation of the mean.
The photophysical and photochemical properties of the library of 4-substituted CyHQ-protected acetates
were compared with the literature data for BHQ-OAc and CyHQ-OAc (Table 2). All the derivatives tested
exhibited good solubility (> 0.1 mM) in the simulated physiological buffer KMOPS used for the photochemical
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experiments. The values of molar absorptivity (e) at 365 nm (the wavelength used to perform 1PE experiments)
-1
-1
30,31,45,46
ranged from 4150 to 8200 M cm , in line with those of other CyHQ-based PPG-effector conjugates.
Substitution at the 4-position of the quinoline core had a large impact on the photochemical behavior of
the chromophore. Strong electron-withdrawing groups (e.g., cyano 12b) and extended conjugation (e.g.,
ethynylbenzene 12e) resulted in red-shifted absorption and emission wavelengths (33 and 19 nm, respectively),
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
but the photolysis quantum yield was low (F = 0.00025 and 0.04, respectively). This can be explained by the
u
larger Stokes shift. The Stokes shift is the difference between the wavelengths of emission and absorbance of
the same electronic transition, and gives an account of the energy lost through vibrational relaxation and solvent
6
1
reorganization processes. High Stokes shift values correspond to a lower energy of the S singlet excited state,
1
which can result in a decreased reaction quantum yield. The introduction of strong electron-donating
substituents (e.g., dimethylamino 12c) also negatively impacted the photochemical properties, whereas weaker
electron-donating groups (e.g., morpholino 12d and methyl 12f) had a positive effect. In particular, the 4-methyl
derivative 12f exhibited a 4-fold increase of d (1.21 GM, Table 2) compared to unsubstituted CyHQ-OAc (0.32
u
GM), while retaining a good quantum yield. Furthermore, this compound had the lowest Stokes shift for the
whole series (80 nm) reinforcing the hypothesis that this parameter is an important predictor of efficient
photolysis reaction.
Table 2. Photophysical and photochemical data for 4-substituted CyHQ acetatesa
C4
λ
abs
λ
em
Stokes shift
ε
365
Sensitivity
(ε
754
δ
u
t
d
(h)
Compound
F
u
-1
-1
b
c
Substituent
(nm)
369
364
369
397
348
355
383
365
364
371
369
371
363
361
370
363
370
370
370
369
370
370
378
370
(nm)
500
449
460
523
443
447
504
445
458
470
465
465
516
495
467
454
474
485
489
473
476
476
462
485
(nm)
(M cm )
2600
7700
6650
4560
4670
5860
5580
5840
4800
4480
5020
6710
6750
6480
8200
7930
5220
6260
7810
4890
5000
6000
4150
4960
F
u
)
(GM)
0.59
0.32
0.48
d
BHQ-OAc
H
H
131
85
0.29
0.31
0.30
0.00025
0.22
0.48
0.04
0.24
0.44
0.44
0.50
0.42
0.04
0.19
0.14
0.002
0.44
0.23
0.14
0.003
0.31
0.40
0.39
0.35
71
484
217
1283
213
338
262
373
379
405
400
572
1199
1421
672
402
393
787
592
126
339
1356
616
538
d
CyHQ-OAc
2387
1981
1
1
2a
2b
Cl
CN
91
e
1
126
95
n.p.
1
2c
2d
2e
2f
NMe
2
1016
2791
198
0.10
1.10
1
morpholine
ethynylbenzene
Me
92
e
1
121
80
n.p.
1
1424
2119
1979
2779
2869
262
1.21
f
e
1
2g
3-pyrrole
Ph
94
n.p.
1
2h
99
0.67
2.12
1.43
0.04
0.07
0.96
1
2i
4-Me-Ph
4-MeO-Ph
4-CN-Ph
96
1
2j
94
1
2k
153
134
97
12l
12m
12n
12o
12p
4-CO
2
H-Ph
1247
1164
20
4-F-Ph
e
4-Me
2
N-Ph
91
n.p.
3-Me-Ph
3-MeO-Ph
3-F-Ph
104
115
119
104
106
106
84
2282
1443
1071
13
1.11
0.73
0.99
1
2q
e
1
2r
2s
3-Me
3,5-(MeO)
3,4,5-(MeO)
2
N-Ph
-Ph
-Ph
n.p.
1
2
1520
2412
1614
1733
2.07
1.83
0.55
0.50
1
2t
3
1
2u
2v
4- Me(CHO)N-Ph
3-Me(CHO)N-Ph
1
115
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a0.1 mM solution in KMOPS buffer, pH 7.2. GM = 10 cm s/photon. Time constant of dark hydrolysis in
b
-50
4
c
d
30
e
KMOPS buffer at room temperature. Data from literature except for λem which was measured in this work. No
photolysis. Secondary photoproducts detected. See Table S1 in the Supporting Information for additional data.
f
Modulating the electronic properties of the C4 substituent had dramatic effects on the photochemical
behavior of the CyHQ PPG. For this reason, we synthesized a series of CyHQ derivatives with a range of C4-
phenyl groups bearing different substituents (EWG, EDG) at the para or meta positions (12h-v). Electron
deficient C4-substituents (12k and 12l) resulted in a marked decrease of the photolysis quantum yield (Table 2)
and attributable to high Stokes shift values (153 and 134 nm, respectively). The introduction of a para or meta
dimethylamino group (12n and 12r) also dramatically reduced the quantum yield, and these compounds
exhibited no reactivity through 2PE, as similarly observed for the dimethylamino derivative 12c. Changing the
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
aromatic group to 3-pyrrole (12g) resulted in an increase of the quantum yield (F
of sensitivity to 2PE. When a weak EWG or EDG was attached to the aromatic ring, we observed an increase in
the value of d (0.49-2.12 GM) compared to CyHQ-OAc. Compounds bearing a weakly electron withdrawing
group (e.g., 4-fluoro 12m, 3-methoxy 12p, 3-fluoro 12q), despite having high d values, suffer from low
quantum yields, possibly caused by the increased Stoke shift values. The introduction of a second methoxy
group (12s) restored the F value to that of 4-unsubstituted CyHQ (0.31) and enhanced d by more than 6-fold
2.07 GM). The 3,4,5-trimethoxy derivative 12t showed a high d value (1.83 GM) and excellent quantum yield
= 0.40). The best PPG of the series was derivative 12i, bearing a para-tolyl group at the 4-position, which
(2.12 GM) and F (0.50). The former represents a 7-fold increase from the
u
= 0.44), but a complete loss
u
u
u
u
(
(
u
F
u
exhibited the highest values of d
value of d for CyHQ-OAc.
An important requirement for a good PPG for biological use is the stability toward spontaneous hydrolysis
u
u
u
in the dark to avoid the activation of the target before light exposure. The time constants of dark hydrolysis (t
for each derivative (Table 2) were obtained by incubating the compounds in KMOPS buffer at room
temperature in the dark, monitoring the degradation at different time intervals over 7 days by HPLC. All
d
)
compounds displayed excellent stability in the dark with values of t typically above 10 days.
d
From the evaluation of the photophysical and photochemical properties of the of the C4-substituted
acetates, several compounds stand out as good PPGs with enhanced sensitivity to 2PE compared to
unsubstituted CyHQ. The 4-methylphenyl derivative 12i represents the best compound in terms of photolysis
efficiency and sensitivity to 2PE, together with the 3,5-dimethoxyphenyl derivative 12s, which exhibits the
second highest value of d
u
. Compound 12t is interesting because it is extremely stable toward dark hydrolysis
(t
d
= 56 days), while retaining an excellent quantum yield and 2PE sensitivity; therefore, it would be useful for
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protecting buffer-labile molecules. The 4-methyl derivative 12f has good potential, despite having slightly
inferior photolysis performance, because it displays high solubility (data not shown) in aqueous media and
would be suitable for mediating the photolytic release of lipophilic leaving groups.
Hammett analysis was used to verify the correlation between the electronic effects on position C4 and the
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
photochemical properties. The sensitivity (e·F
u
) and d
u
values of compounds 12h-v were plotted against the
6
2
2
Hammett constants (s) of the substituents and fitted to a linear curve (Figure 4). A good correlation (R =
0.81) was found when comparing s values with sensitivity, demonstrating the positive effect of an electron-rich
C4-phenyl group on the photochemistry. This result corroborated previous mechanistic studies that suggested
4
3
the development of positive charge on the C2 methylene group during the course of the cleavage reaction. The
enhanced transmission of electron-density from the meta position results in stabilization of the cation, increasing
its lifetime and enabling more efficient photolysis. A similar observation was made when d vs Hammett
u
constant was plotted, albeit with a lower value of R2.
3
2
2
1
1
000
500
000
500
000
ꢀ
ꢁꢂꢃꢄꢅꢄꢆꢇꢈꢉꢈꢊꢋꢌꢂꢄꢍꢄꢇꢎꢏꢐꢊꢑꢄ
ꢇ
ꢒ ꢄꢅꢄꢎꢊꢓꢐꢇꢋ
5
00
0
-
0.5
-0.2
0.1
0.4
0.7
1
Hammett Constant
3
ꢀ
ꢁꢂꢃꢄꢅꢄꢆꢇꢈꢉꢊꢉꢋꢂꢄꢌꢄꢇꢈꢍꢊꢎꢄ
ꢍ
ꢏ ꢄꢅꢄꢐꢈꢑꢒꢐꢊ
2
1
0
.5
2
.5
1
.5
0
-
0.5
-0.2
0.1
0.4
0.7
1
Hammett Constant
Figure 4. Hammett correlation plots for compounds 12h-v. (Top) Sensitivity values were plotted against the
6
2
Hammett constant and fitted to a linear curve (blue line). (Bottom) The values of d were plotted against the
u
6
2
Hammett constant and fitted to a linear curve (red line). Compounds 12m and 12r were omitted because they
do not photolyze through 2PE.
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3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
We prepared an additional set of derivatives bearing a leaving group with a strong UV absorbance to
monitor and quantify the released product, because acetate release cannot be monitored by HPLC.
-
1
-1
Homopiperonylic acid (e = 1870 M cm at 280 nm) was selected as the leaving group, and it was conjugated to
those 4-substituted CyHQ PPGs that showed the best overall photochemical properties, generating compounds
16f,i,s,t (Scheme 5). CyHQ-protected homopiperonylate 15 was prepared for comparison. The synthesis of this
set of derivatives required the preparation of acyl chloride 14 from homopiperonylic acid with oxalyl chloride
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
6
3
and DMF (cat.) in toluene (97% yield). Subsequently, 14 was reacted with MOM-CyHQ-OH and each primary
alcohol 10f,i,s,t, followed by MOM group deprotection in TFA, affording the target compounds 15 and 16f,i,s,t
(Scheme 5).
Scheme 5. Synthesis and photolysis reaction of 4-substituted CyHQ-protected homopiperonylic acids 15 and
1
6f,i,s,t.
R
Cl
1
. DMAP
O
+
OH
Py, CHCl
3
O
MOMO
N
2
. TFA, CH Cl
O
R
N
2
2
CN
MOM-CyHQ-OH (R = H)
1
4
15-23%
1
0f,i,s,t
f: R = Me
i: R = 4-MePh
s: R = 3,5-(MeO) Ph
O
HO
2
t: R = 3,4,5-(MeO) Ph
CN
O
3
O
O
15 (R = H)
1
6f,i,s,t
R
R
N
OH
O
N
CN
O
hν
buffer*
O
17
8f,i,s,t
1
CN
O
O
O
O
O
O
1
5 (R = H)
6f,i,s,t
O
*20% CH CN in
3
1
KMOPS, pH 7.2
19
The homopiperonylate derivatives were subjected to the same photochemical evaluation performed for
compounds 12a-v. In this case, the solubility of the constructs was affected by the lipophilicity of the leaving
group, so acetonitrile (20% v/v) was added to the KMOPS buffer to facilitate complete solubilization. The
photophysical constants (labs, lem, Stokes shift, and e365) were equivalent to those of the corresponding acetates
(Table 3), suggesting that the introduction of the homopiperonylate group did not impact the photophysical
properties of the 4-substituted CyHQ PPG. The photochemical properties were greatly enhanced by this new
leaving group. The new constructs were exceptionally stable toward hydrolysis in the dark, showing almost no
spontaneous decomposition for up to 7 days of incubation in KMOPS buffer (Table 3). The photolysis reaction
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was extremely efficient at 365 nm (1PE) and 740 nm (2PE) and high yielding (Figure 5). The photocleavage
was generally completed within 30-40 s at 365 nm (1PE). Through 2PE (740 nm), the 4-substituted CyHQ
derivatives 16f,i,s,t released homopiperonylate faster and more effectively than the parent CyHQ derivative 15.
Compounds 16f,i,s,t exhibited the highest values of F
= 0.62-0.88 and d = 1.84-2.64 GM). It is evident that the high values of F
substitution since the unsubstituted control derivative 15 displays only modest increases of F
u
and d
u
ever recorded for quinoline-based PPGs (F
and d are determined by the 4-
and d (0.4 and
u
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
u
u
u
u
u
0.66 GM, respectively) compared to CyHQ-OAc. We monitored and quantified by HPLC the release of
homopiperonylate, and the chemical yields obtained were 63-92% (Table 3, Figures S34 and S35, Supporting
Information), confirming the efficiency of these 4-substituted CyHQ PPGs and the broad applicability of the
strategy. A systematic evaluation of the solubility of the derivatives in pure KMOPS buffer was carried out to
check this aspect of the biocompatibility of the probes (Table 3). With the exception of compound 16s, the PPG
constructs display solubility values compatible with the typical concentrations used for photoactivation
experiments in biological preparations (1-10 µM).64,65
Table 3. Photophysical and photochemical data for 4-substituted CyHQ-protected homopiperonylic acids 15
and 16f,i,s,t.a
Stokes
shift
(nm)
C4
l
(nm)
abs
l
(nm)
em
e
365
Sensitivity
e F
d
u
t
(h)
d
Yield
(%)
Solubility
µ
( M)
Cmp
F
u
d
-1
-1
b
c
e
Substituent
(M cm )
(
u
)
(GM)
15
H
Me
367
367
373
374
374
449
444
463
481
471
82
77
6560
3500
4530
4310
5240
0.40
0.88
0.74
0.81
0.62
2605
3097
3346
3494
3260
0.66
1.84
2.25
2.64
2.37
2568
1783
78
73
74
63
92
109
98
1
6f
6i
f
1
4-Me-Ph
90
n.h.
24
g
1
6s
6t
3,5-(MeO)
2
Ph
107
97
n.h.
n.s.
18
1
3,4,5-(MeO)
3
-Ph
n.h.
4
a0.1 mM solution in KMOPS buffer, pH 7.2, with 20% of CH
constant of hydrolysis in KMOPS buffer (with 20% CH
Chemical yield of released homopiperonylate under 1PE. In KMOPS buffer without acetonitrile co-solvent.
CN added. GM = 10 (cm s)/photon. Time
b
-50
c
3
3
CN added) in the dark at room temperature.
d
e
f
g
No hydrolysis (< 2% hydrolysis detected after 7 days). Not soluble. See Table S2 in the Supporting
Information for additional data.
1
00
80
60
40
20
0
-0
20
40
Time (s)
60 100
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6
100
1
1
5
6f
8
6
0
0
16i
1
1
1
1
6s
6t
9 from 15
9 from 16f
0
1
2
3
4
5
6
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8
9
0
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9
0
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8
9
0
1
2
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9
0
1
2
3
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5
6
7
8
9
0
40
19 from 16i
19 from 16s
2
0
19 from 16t
0
-
0
10 20 30 40 50 60
Time (min)
Figure 5. Time courses for the photolyses of 15 and 16f,i,s,t through (top) 1PE (LED, 365 nm) and (bottom)
PE (Ti:sapphire laser, 740 nm)). The percentage remaining was determined by HPLC analysis and is the
average of three runs. The percent yield of homopiperonylic acid 19 is also given. Lines are least-squares fits of
a simple exponential decay (solid lines) and an exponential rise to max (dotted lines). All fits for the photolyses
via 2PE approach zero asymptotically. Error bars represent the standard deviation of the mean.
2
To demonstrate that the photochemistry was driven by 2PE at 740 nm, we conducted a power dependence
2PE-mediated photolysis experiment on compounds 16i and 16s. The photolysis of PPGs through 2PE will
depend quadratically on the average power of the laser.17,66 Solutions of 16i and 16s were each irradiated for 15
minutes using different laser powers (250-650 mW) and the resulting percentage of photolysis was plotted
b
2
against the laser power (Figure 6). The data for compound 16s fit to a power curve (y = ax ) with b = 2.09 (R =
2
0
.999), confirming a 2PE mechanism. Derivative 16i fit less well (b = 1.28, R = 0.996). Both compounds
2
exhibited a quadratic dependence of the photolysis reaction on the laser power, giving R =0.999 for the
corresponding curve fits, which also support a 2PE mechanism.
4
3
2
1
0
0
0
0
16i
6s
1
0
0
200
400
600
800
Laser Average Power (mW)
Figure 6. Dependence of photolysis rate on average laser power. Compounds 16i (blue dots) and 16s (red dots)
were photolyzed at different laser powers for 15 min. Remaining concentrations were determined by HPLC
analysis and are the average of three runs. Lines are least-squares fits of a power equation (y = ax ). For 16i, a =
.86 ´ 10 , b = 1.28. For 16s, a = 3.36 ´ 10 , b = 2.09. The data also fit a quadratic equation (y = ax + bx + c).
b
-
3
-5
2
5
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-5
-2
-2
-5
-2
For 16i a = 2.29 ´ 10 , b = 2.21 ´ 10 , c = 1.21 ´ 10 , R
1
2
= 0.999. For 16s a = 6.51 ´ 10 , b = 4.43 ´ 10 , c =
-2
2
.01 ´ 10 , R = 0.999. Error bars represent the standard deviations of the mean.
CONCLUSION
We have created a series of PPGs that are efficiently photolyzed through 2PE and are well-suited for
physiological studies. Functionalizing the C4 position of the CyHQ PPG with electron-donating substituents
remarkably improved the photochemical properties, in particular F (0.50) and d (2.12 GM). Moreover, these
-substituted-CyHQ PPGs exhibited good solubility at physiological pH and stability toward spontaneous
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
u
u
4
hydrolysis in the dark, and underwent rapid, clean photochemical reactions without generating harmful side
products. Hammett analysis showed a good correlation between the electronic effects and the photolysis
efficiency, demonstrating the positive influence on the photochemistry of an electron-rich group at the 4-
position of CyHQ. This result was in accordance to our previous mechanistic investigations suggesting a
positive charge development on the C2 methylene group during the course of the cleavage reaction. Studies on
the photocleavage of several 4-substituted CyHQ PPG-homopiperonylic acid conjugates demonstrated a high
chemical yield of a model biological effector (63-92%). The photochemical efficiency of these derivatives was
higher than the corresponding acetates: F
u
= 0.62-0.88 and d = 1.84-2.64 GM. Taken together, these factors
u
will make these quinoline-based PPGs useful for photoactivation experiments in vitro as well as in tissue and
whole animals, where irradiation at long wavelengths is required to ensure low photodamage and deeper tissue
penetration. Results of experiments that demonstrate the effectiveness of these probes in physiology will be
reported in due course.
EXPERIMENTAL SECTION
Synthesis
General
Reagents and solvents were purchased from commercial sources and used without purification. For reactions
carried out above room temperature, an oil bath was used as the source of heating. The UV spectra were
recorded on a Lambda25 UV-Vis-NIR spectrophotometer (Perkin Elmer). Emission spectra were obtained with
1
13
a Perkin Elmer LS 55 fluorescence spectrometer. H NMR and C NMR spectra were recorded using a Bruker
Avance III HD 500 or 600 MHz NMR spectrometer. uHPLC analysis and preparative HPLC purifications were
carried on an Agilent Infinity series system with an autosampler and diode array detector using Zorbax eclipse
C-18 reverse phase columns, having a mobile phase composed of water with 0.1% TFA and acetonitrile. HRMS
was performed on an Agilent 6540 HD Accurate Mass QTOF/LC/MS with electrospray ionization (ESI).
Purification was carried out using flash chromatography on an Isolera Spektra 4 with Biotage SNAP cartridges
packed with KPSIL silica. KMOPS buffer consisted of 100 mM KCl and 10 mM MOPS (3-(N-
morpholino)propanesulfonic acid) titrated to pH 7.2 with NaOH 0.1 N.
General procedure for the preparation of 2-methyl-substituted acetates 1a-f.
To a solution of MOM-CyHQ-R-OH (30 mg, 1 eq) in CH
4
6
2
Cl (5 mL), pyridine (5 eq), and 4-
2
dimethylaminopyridine (1 eq) were added. The mixture was cooled to 0 °C with an ice-bath and acetic
anhydride (4 eq) was added dropwise. The mixture was stirred at 0 °C for 30 min, then at room temperature for
h. The reaction mixture was diluted with CH
saturated ammonium chloride solution (10 mL) and H
dryness. The resulting residue was purified by column chromatography (hexanes/EtOAc gradient) to yield the
corresponding MOM-protected acetate, which was dissolved in CH Cl (2 mL). TFA (0.2 mL) was added
6
2
Cl
2
(20 mL), and the resulting solution was washed with a
2
O (2 × 10 mL), dried over MgSO , and concentrated to
4
2
2
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8
9
1
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1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
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5
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5
5
6
dropwise, and the reaction was stirred for up to 5 h until HPLC showed complete consumption of the starting
material. After evaporation of the solvent, the resulting residue was purified either by trituration with
tetrahydrofuran or by column chromatography with MeOH/CH
2
Cl
2
, affording the respective acetates 1a-f.
1
1-(8-cyano-7-hydroxyquinolin-2-yl)ethyl acetate (1a). (26 mg, 87% yield). H NMR (500 MHz, methanol-d
4
,
d): 8.26 (d, J = 8.4 Hz, 1H), 8.01 (d, J = 9.0 Hz, 1H), 7.47 (d, J = 8.3 Hz, 1H), 7.27 (d, J = 9.0 Hz, 1H), 6.02 (q,
1
3
J = 6.8 Hz, 1H), 2.20 (s, 3H), 1.68 (d, J = 6.8 Hz, 3H); C NMR{1H} (126 MHz, methanol-d
4
, d): 171.0,
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
164.13, 162.9, 148.3, 137.3, 133.7, 121.5, 117.7, 116.4, 114.7, 94.5, 73.2, 19.7, 19.4; HRMS (ESI-QTOF) m/z:
+
[M + H] calcd for C14
H
13
N
2
3
O , 257.0921; found, 257.0913.
1
1-(8-cyano-7-hydroxyquinolin-2-yl)-2-methylpropyl acetate (1b). (22 mg, 75% yield). H NMR (500 MHz,
methanol-d , d): 8.24 (d, J = 8.4 Hz, 1H), 8.01 (d, J = 9.0 Hz, 1H), 7.41 (d, J = 8.3 Hz, 1H), 7.26 (d, J = 9.0 Hz,
1H), 5.75 (d, J = 5.5 Hz, 1H), 2.54 – 2.35 (m, 1H), 2.22 (s, 3H), 0.99 (dd, J = 18.9, 6.8 Hz, 6H); C NMR{1H}
(126 MHz, methanol-d , d): 171.2, 164.0, 161.7, 148.3, 136.7, 133.7, 121.4, 117.6, 117.3, 114.8, 94.5, 81.1,
32.5, 19.5, 18.1; HRMS (ESI-QTOF) m/z: [M + H] calcd for C16
4
1
3
4
+
H
17
N
2
O
3
, 285.1234; found, 285.1234.
1
(
8-cyano-7-hydroxyquinolin-2-yl)(phenyl)methyl acetate (1c). (20 mg, 69% yield). H NMR (500 MHz,
methanol-d , d): 8.16 (d, J = 8.4 Hz, 1H), 7.93 (d, J = 9.1 Hz, 1H), 7.56 – 7.50 (m, 2H), 7.42 (d, J = 8.4 Hz, 1H),
4
1
3
7
.36 (dd, J = 8.3, 6.6 Hz, 2H), 7.33 – 7.27 (m, 1H), 7.24 (d, J = 9.0 Hz, 1H), 6.93 (s, 1H), 2.29 (s, 3H); C
NMR{1H} (126 MHz, methanol-d , d): 170.7, 164.1, 161.3, 148.3, 138.4, 137.2, 133.7, 128.3, 128.1, 127.2,
4
+
1
3
21.4, 117.8, 117.1, 114.8, 94.6, 78.3, 19.7; HRMS (ESI-QTOF) m/z: [M + H] calcd for C19
19.1077; found, 319.1081.
H
15
N
2
3
O ,
1
(
8-cyano-7-hydroxyquinolin-2-yl)(cyclopropyl)methyl acetate (1d). (9 mg, 30% yield). H NMR (500 MHz,
methanol-d , d): 8.26 (d, J = 8.4 Hz, 1H), 8.01 (d, J = 9.1 Hz, 1H), 7.52 (d, J = 8.4 Hz, 1H), 7.27 (d, J = 9.0 Hz,
H), 5.34 (d, J = 8.7 Hz, 1H), 2.20 (s, 3H), 1.44 (dddd, J = 12.9, 8.5, 6.5, 4.9 Hz, 1H), 0.73 – 0.58 (m, 4H); C
NMR{1H} (126 MHz, methanol-d , d): 171.0, 164.0, 161.7, 148.3, 137.1, 133.7, 121.6, 117.6, 117.0, 114.7,
4
1
3
1
4
+
9
2
4.6, 80.6, 19.7, 15.0, 3.1, 2.2; HRMS (ESI-QTOF) m/z: [M + H] calcd for C16
83.1079.
H
15
N
2
O
3
, 283.1077; found,
1
1
-(8-cyano-7-hydroxyquinolin-2-yl)-2,2,2-trifluoroethyl acetate (1e). (15 mg, 49% yield). H NMR (500 MHz,
methanol-d , d): 8.38 (d, J = 8.4 Hz, 1H), 8.09 (d, J = 9.1 Hz, 1H), 7.62 (d, J = 8.4 Hz, 1H), 7.35 (d, J = 9.1 Hz,
4
1
3
1
H), 6.46 (q, J = 6.9 Hz, 1H), 2.30 (s, 3H); C NMR{1H} (126 MHz, methanol-d
4
, d): 168.8, 164.5, 153.1,
1
48.3, 137.7, 133.8, 123.1 (q, J = 287.3 Hz), 122.3, 118.9, 117.6, 114.3, 94.7, 73.0 (q, J = 32.3 Hz), 19.0;
+
HRMS (ESI-QTOF) m/z: [M + H] calcd for C14
H
10
F
3
N
2
O
3
, 311.0638; found, 311.0605.
1
1
d
–
-(8-cyano-7-hydroxyquinolin-2-yl)but-3-en-1-yl acetate (1f). (20 mg, 68% yield). H NMR (500 MHz, DMSO-
6
, d): 8.37 (d, J = 8.5 Hz, 1H), 8.11 (d, J = 9.1 Hz, 1H), 7.47 (d, J = 8.4 Hz, 1H), 7.35 (d, J = 9.1 Hz, 1H), 5.92
5.86 (m, 1H), 5.86 – 5.77 (m, 1H), 5.12 (dq, J = 17.1, 1.6 Hz, 1H), 5.06 (ddd, J = 10.3, 2.1, 1.1 Hz, 1H), 2.81
dddt, J = 14.5, 6.5, 5.0, 1.4 Hz, 1H), 2.76 – 2.66 (m, 1H), 2.15 (s, 3H); C NMR{1H} (126 MHz, DMSO-d
13
(
6
,
d): 170.5, 164.6, 161.5, 148.3, 138.1, 134.6, 133.9, 121.58, 118.8, 118.6, 117.7, 115.7, 94.5, 75.7, 38.7, 21.3;
+
HRMS (ESI-QTOF) m/z: [M + H] calcd for C16
H
15
N
2
3
O , 283.1077; found, 283.1066.
Preparation of intermediates 7 and 8
7-methoxy-2-methylquinolin-4-ol (3). A mixture of meta-anisidine (2.24 mL, 20.00 mmol, 1 eq) and ethyl
acetoacetate (3.04 mL, 24.00 mmol, 1.2 eq) was stirred at 100 °C for 16 h. The reaction mixture was cooled to
room temperature and added dropwise to a refluxing (260 °C) solution of diphenyl ether (25 mL). After stirring
at reflux for 1.5 h, the mixture was cooled to room temperature and stirred overnight. The resulting precipitate
was collected by filtration, washed with diethyl ether (3 × 30 mL), and dried under vacuum to yield 3 as a dark
1
brown, powdery solid (1.05 g, 5.55 mmol, 60%). H NMR (500 MHz, chloroform-d, δ): 10.43 (s, 1H), 8.25 (d, J
1
3
= 8.9 Hz, 1H), 6.92 (dd, J = 9.0, 2.3 Hz, 1H), 6.88 (s, 1H), 6.11 (s, 1H), 3.83 (s, 3H), 2.41 (s, 3H); C
NMR{1H} (126 MHz, DMSO-d , d): 162.1, 157.1, 130.5, 127.1, 123.9, 119.1, 113.0, 108.6, 99.3, 55.8, 19.8;
6
+
HRMS (ESI-QTOF) m/z: [M + H] calcd for C11
H
12NO , 190.0863; found, 190.0860.
2
4
-chloro-7-methoxy-2-methylquinoline (4). A solution of 3 (6.88 g, 36.36 mmol, 1 eq) in POCl
heated to reflux (110 °C) and stirred for 3 h. The reaction mixture was cooled to room temperature and then
added dropwise to a flask containing H O (250 mL) on ice. The pH of the solution was raised to 7 with 2 M
NaOH. The resulting precipitate was collected by vacuum filtration, washing with H O, to yield 4 as a pink,
, d): 7.99 (d, J = 9.2 Hz, 1H), 7.33 (s,
3
(17 mL) was
2
2
1
flaky solid (6.66 g, 32.07 mmol, 88%). H NMR (500 MHz, methanol-d
4
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1
H), 7.26 (d, J = 2.6 Hz, 1H), 7.21 (dd, J = 9.2, 2.6 Hz, 1H), 3.94 (s, 3H), 2.63 (s, 3H); C NMR{1H} (126
MHz, methanol-d , d): 161.8, 159.4, 149.7, 142.6, 124.6, 119.6, 119.4, 119.3, 105.7, 54.7, 23.1; HRMS (ESI-
QTOF) m/z: [M + H] calcd for C11
4
+
H11ClNO, 208.0524; found, 208.0529.
4-chloro-2-methylquinolin-7-ol (5). A solution of 4 (6.66 g, 32.07 mmol, 1 eq) in 48% HBr (133.25 mL), was
heated to reflux (125 °C) under a N atmosphere and stirred overnight. The reaction mixture was then cooled to
room temperature, placed in an ice-bath, and diluted with H O (50 mL). K CO (powder) was added until the
mixture reached pH 7. The mixture was stirred for a few hours to ensure all of the product had precipitated, and
the precipitate was collected by filtration, washed with H O (4 × 100 mL), and dried under vacuum to yield 5 as
a brown powder (5.19 g, 26.80 mmol, 84%). H NMR (500 MHz, methanol-d , d): 8.09 (d, J = 9.1 Hz, 1H), 7.39
(s, 1H), 7.28 (d, J = 2.3 Hz, 1H), 7.24 (dd, J = 9.0, 2.4 Hz, 1H), 2.67 (s, 3H); C NMR{1H} (126 MHz,
methanol-d , d): 160.3, 159.3, 149.6, 143.1, 125.0, 119.4, 119.0, 118.8, 108.5, 22.8; HRMS (ESI-QTOF) m/z:
[M + H] calcd for C10 ClNO, 194.0367; found, 194.0378.
2
2
2
3
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
2
1
4
1
3
4
+
H
9
8
-bromo-4-chloro-2-methylquinolin-7-ol (6). To a solution of 5 (3.00 g, 15.49 mmol, 1 eq) in CH
acetic acid (0.93 mL, 16.32 mmol, 1.05 eq) was added slowly, followed by NBS (3.3 g, 18.53 mmol, 1.2 eq).
The mixture was stirred at room temperature overnight, then diluted with CH Cl (500 mL) and washed with
O (3 × 200 mL). The aqueous layers were combined and back-extracted with CH Cl (3 × 200 mL). The
organic layers were combined and the solvent was evaporated under vacuum to yield 6 as a dark brown solid
2
2
Cl (38 mL),
2
2
H
2
2
2
1
(4.14 g, 15.19 mmol, 98% yield). H NMR (500 MHz, methanol-d
4
, d): 8.08 (d, J = 9.1 Hz, 1H), 7.43 (s, 1H),
.32 (d, J = 9.1 Hz, 1H), 2.72 (s, 3H); C NMR{1H} (126 MHz, methanol-d , d): 160.4, 157.0, 147.0, 143.0,
23.8, 119.7, 118.4, 110.4, 106.0, 23.3; HRMS (ESI-QTOF) m/z: [M + H] calcd for C10 BrClNO, 271.9472;
1
3
7
1
4
+
H
8
found, 271.9486.
4
-chloro-7-hydroxy-2-methylquinoline-8-carbonitrile (7). To a solution of 6 (4.43 g, 16.34 mmol, 1 eq) in
acetonitrile (35 mL), triethylamine (5.7 mL, 40.40 mmol, 2.5 eq) was added while stirring. The mixture was
cooled to 0 °C with an ice-bath, and a solution of acetyl chloride (1.4 mL, 19.56 mmol, 1.2 eq) in acetonitrile (7
mL) was added dropwise. The ice-bath was removed and the mixture was allowed to reach room temperature
and stirred for 1 h. The solvent was evaporated under vacuum, and the resulting residue was partitioned between
O (100 mL). The layers were separated, and the organic layer was washed with a
O (2 × 50 mL). The organic layer was then evaporated to dryness.
The resulting crude product was dissolved in N,N-dimethylacetamide (20 mL) and added dropwise to a
refluxing (160 °C) solution of copper (I) cyanide (2.93 g, 32.70 mmol, 2 eq) in N,N-dimethylacetamide (15
EtOAc (100 mL) and H
saturated NaHCO solution (50 mL) and H
2
3
2
mL). The reaction mixture was stirred for 1 h and then cooled. Once the temperature had reached 50 °C, H
(100 mL) was slowly added. The resulting slurry was stirred for 1 h at room temperature, and then the
2
O
precipitate was collected by filtration, washed with H
(copper adducts) was suspended in 33 wt% ammonium hydroxide solution (100 mL) and stirred at room
temperature for 1 h. The mixture was filtered through alumina. The pH of the filtrate was adjusted to 3 using
2
O (75 mL), and dried under vacuum. The crude product
36% HCl and then extracted with 2-butanol (3 × 100 mL). The organic layers were combined, washed with H
(50 mL), and then concentrated to dryness. The resulting solid was stirred in acetonitrile (100 mL) and filtered
to remove any insoluble salts. The filtrate was concentrated to dryness to yield 7 as a brown solid (1.83 g, 8.37
, d): 8.13 (d, J = 9.3 Hz, 1H), 7.47 (s, 1H), 7.35 (d, J = 9.3 Hz, 1H),
2.62 (s, 3H); C NMR{1H} (126 MHz, DMSO-d , d): 164.9, 162.0, 149.7, 142.0, 129.9, 120.9, 118.9, 118.1,
2
O
1
mmol, 51%). H NMR (500 MHz, DMSO-d
6
1
3
6
+
115.6, 94.8, 25.1; HRMS (ESI-QTOF) m/z: [M + H] calcd for C11
H
8
ClN O, 219.0320; found, 219.0316.
2
4
-iodo-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (8). To a suspension of 7 (460 mg, 2.10 mmol, 1
Cl (6 mL), TFA (0.96 mL, 12.57 mmol, 6 eq) was added, and the reaction mixture was stirred at
room temperature for 30 minutes. The solvent was removed under vacuum to yield the corresponding
pyridinium salt, which was suspended in anhydrous acetonitrile (30 mL) under a N atmosphere. NaI (3.15 g,
1.04 mmol, 10 eq) was added and the mixture was heated to reflux and stirred for 6 h. The reaction mixture
was then cooled to room temperature, and the solvent evaporated under vacuum. The remaining solid was
dissolved in EtOAc (100 mL) and washed with 5% NaHSO (2 × 20 mL) and H O (3 × 50 mL). The organic
layer was then evaporated to dryness. The residue was suspended in CH Cl (50 mL) and cooled to 0 °C with an
ice-bath. Triethylamine (1.17 mL, 8.40 mmol, 4 eq) was added, followed by a 2 M solution of MOM-Cl (3.15
mL, 6.30 mmol, 3 eq) in CH Cl . The ice-bath was removed and the mixture was stirred at room temperature
overnight. The reaction mixture was diluted with CH Cl (100 mL), then washed with a saturated NaHCO
solution (50 mL) and H O (2 × 50 mL). The organic layer was dried over MgSO and concentrated to dryness.
The crude product was purified by column chromatography (hexanes/EtOAc gradient) to yield 8 as a white solid
eq) in CH
2
2
2
2
3
2
2
2
2
2
2
2
3
2
4
1
(
7
662 mg, 1.87 mmol, 89% over three steps). H NMR (500 MHz, chloroform-d, δ): 8.10 (d, J = 9.4 Hz, 1H),
.86 (s, 1H), 7.52 (d, J = 9.3 Hz, 1H), 5.47 (s, 2H), 3.59 (s, 3H), 2.74 (s, 3H); C NMR{1H} (126 MHz,
13
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2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
chloroform-d, δ): 162.4, 162.0, 148.1, 137.4, 133.0, 123.8, 115.8, 114.4, 111.2, 99.5, 95.1, 56.9, 24.9; HRMS
+
(ESI-QTOF) m/z: [M + H] calcd for C13
H12IN
2
2
O , 354.9938; found, 354.9945.
Preparation of compounds 9a-e
4-chloro-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (9a). A suspension of 7 (261 mg, 1.2 mmol, 1
eq) in CH Cl (30 mL) was cooled to 0 °C with an ice-bath. Triethylamine (0.67 mL, 4.8 mmol, 4 eq) was
added, followed by a 2 M solution of MOM-Cl (1.8 mL, 3.6 mmol, 3 eq) in CH Cl . The ice-bath was removed
and the mixture was stirred at room temperature overnight. The reaction mixture was diluted with CH Cl (50
mL) and washed with a saturated NaHCO solution (30 mL) and H O (2 × 30 mL). The organic layer was dried
over MgSO and concentrated to dryness. The crude product was purified by column chromatography
hexanes/EtOAc gradient) to yield 9a as a white solid (298 mg, 1.14 mmol, 95%). H NMR (500 MHz,
chloroform-d, δ): 8.33 (d, J = 9.4 Hz, 1H), 7.57 (d, J = 9.4 Hz, 1H), 7.38 (s, 1H), 5.47 (s, 2H), 3.60 (s, 3H), 2.78
2
2
2
2
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
2
2
3
2
4
1
(
1
3
(
1
s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.5, 162.5, 149.6, 142.6, 130.0, 121.7, 120.0, 115.4,
+
14.5, 99.7, 95.1, 57.0, 25.5; HRMS (ESI-QTOF) m/z: [M + H] calcd for C13
H12ClN
2
2
O , 263.0582; found,
263.0578.
7-(methoxymethoxy)-2-methylquinoline-4,8-dicarbonitrile (9b). Compound 7 (300 mg, 1.37 mmol, 1 eq) was
dissolved in N,N-dimethylacetamide (5 mL) and added dropwise to a refluxing (160 °C) solution of copper (I)
cyanide (490 mg, 5.48 mmol, 4 eq) in N,N-dimethylacetamide (5 mL). The reaction mixture was stirred
overnight and then cooled. Once the temperature had reached 50 °C, H
resulting slurry was stirred for 1 h at room temperature, and then the precipitate was collected by filtration,
washed with H O (75 mL), and dried under vacuum. The crude product (copper adducts) was suspended in 33
2
O (100 mL) was slowly added. The
2
wt% ammonium hydroxide solution (100 mL) and stirred at room temperature for 1 h. The mixture was filtered
through alumina. The pH of the filtrate was adjusted to 3 using 36% HCl and then extracted with 2-butanol (3 ×
1
00 mL). The organic layers were combined, washed with H O (50 mL), and then concentrated to dryness. The
2
resulting solid was stirred in acetonitrile (100 mL), then filtered to remove any insoluble salts. The filtrate was
concentrated to dryness, and the resulting residue was subjected to the procedure described for converting 7 into
the MOM ether 9a, purifying by column chromatography (hexanes/EtOAc gradient) to yield 9b as a dark solid
1
(120 mg, 0.47 mmol, 35%). H NMR (500 MHz, chloroform-d, δ): 8.27 (d, J = 9.3 Hz, 1H), 7.70 (d, J = 9.3 Hz,
1
3
1H), 7.62 (s, 1H), 5.50 (s, 2H), 3.61 (s, 3H), 2.87 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 163.0,
162.0, 148.6, 130.4, 125.3, 119.1, 119.0, 117.0, 114.9, 113.9, 100.3, 95.2, 57.1, 25.5; HRMS (ESI-QTOF) m/z:
+
[M + H] calcd for C14
H
12
N
3
2
O , 254.0924; found, 254.0913.
4-(dimethylamino)-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (9c). A solution of 7 (300 mg, 1.37
mmol, 1 eq) in N,N-dimethylacetamide (10 mL) was stirred at reflux (160 °C) overnight. After cooling, a
saturated solution of ammonium chloride (20 mL) was added and the resulting slurry was extracted with EtOAc
(
3 × 50 mL). The combined EtOAc extracts were dried over MgSO and concentrated to dryness. The resulting
4
residue was subjected to the procedure described for converting 7 into the MOM ether 9a, purifying by column
1
chromatography (hexanes/EtOAc gradient) to yield 9c as a dark solid (180 mg, 0.66 mmol, 48%). H NMR (500
MHz, chloroform-d, δ): 8.15 (d, J = 9.4 Hz, 1H), 7.33 (d, J = 9.4 Hz, 1H), 6.63 (s, 1H), 5.43 (s, 2H), 3.59 (s,
1
3
3
1
H), 3.03 (s, 6H), 2.70 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.5, 161.3, 157.7, 150.9, 130.5,
+
16.5, 115.4, 112.0, 107.6, 99.6, 94.9, 56.8, 43.9, 29.3; HRMS (ESI-QTOF) m/z: [M + H] calcd for
C
15
H
18
N
3
2
O , 272.1394; found, 272.1409.
7-(methoxymethoxy)-2-methyl-4-morpholinoquinoline-8-carbonitrile (9d). To a solution of 7 (100 mg, 0.45
mmol, 1 eq) in N,N-dimethylacetamide (2 mL), K CO (190 mg, 1.37 mmol, 3 eq) and morpholine (78 µL, 0.90
2
3
mmol, 2 eq) were added. The mixture was stirred overnight at 100 °C. After cooling, a saturated solution of
ammonium chloride (20 mL) was added, and the resulting slurry was extracted with EtOAc (3 × 50 mL). The
combined EtOAc extracts were dried with MgSO
4
and concentrated to dryness. The resulting residue was
subjected to the procedure described for converting 7 into the MOM ether 9a, purifying by column
1
chromatography (hexanes/EtOAc gradient) to yield 9d as a dark yellow solid (58 mg, 0.18 mmol, 39%). H
NMR (500 MHz, Chloroform-d, δ) 8.07 (d, J = 9.4 Hz, 1H), 7.35 (d, J = 9.3 Hz, 1H), 6.70 (s, 1H), 5.39 (s, 2H),
1
3
3.94 (t, J = 4.6 Hz, 4H), 3.54 (s, 3H), 3.23 – 3.09 (m, 4H), 2.67 (s, 3H).; C NMR{1H} (126 MHz, methanol-
, d): 166.9, 161.1, 155.5, 142.6, 132.6, 115.8, 112.0, 111.8, 106.5, 88.1, 66.0, 52.5, 19.3; HRMS (ESI-QTOF)
d
4
+
m/z: [M + H] calcd for C17
H
20
N
3
3
O , 314.1499; found, 314.1497.
7-(methoxymethoxy)-2-methyl-4-(phenylethynyl)quinoline-8-carbonitrile (9e). To a solution of 8 (60 mg, 0.17
mmol, 1 eq) in anhydrous dioxane (5 mL) under a N atmosphere, triethylamine (0.12 mL, 0.8 mmol, 4.5 eq)
2
and phenylacetylene (0.04 mL, 0.34 mmol, 2 eq) were added dropwise, followed by dropwise addition of a
solution of RuPhos (7 mg, 0.017 mmol, 0.1 eq), palladium acetate (2 mg, 0.008 mmol, 0.05 eq), and copper (I)
20
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2
3
4
5
6
7
8
9
iodide (2 mg, 0.008 mmol, 0.05 eq) in anhydrous dioxane (2 mL). The mixture was heated to 80 °C and stirred
under a N
celite. The filtrate was washed with H
MgSO , concentrated to dryness, and purified by column chromatography (hexanes/EtOAc gradient) to yield 9e
as a clear oil (48 mg, 0.15 mmol, 87%). H NMR (500 MHz, chloroform-d, δ): 8.40 (d, J = 9.2 Hz, 1H), 7.66 –
2
atmosphere for 1 h. After cooling, the mixture was diluted with EtOAc (50 mL) and filtered through
2
O (2 × 50 mL) and brine (50 mL). The organic layer was dried over
4
1
1
3
7.61 (m, 2H), 7.55 – 7.51 (m, 1H), 7.48 – 7.40 (m, 4H), 5.46 (s, 2H), 3.59 (s, 3H), 2.78 (s, 3H); C NMR{1H}
(126 MHz, chloroform-d, δ): 162.1, 161.9, 148.6, 132.0, 131.8, 129.9, 129.6, 128.7, 124.0, 121.8, 121.1, 114.9,
+
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
114.8, 99.6, 98.9, 95.1, 84.3, 56.9, 25.5; HRMS (ESI-QTOF) m/z: [M + H] calcd for C21
H
17
N
2
2
O , 329.1285;
found, 329.1274.
General procedure for Suzuki coupling reaction
Compound 8 (100 mg, 0.28 mmol, 1 eq), the boronic acid (0.42 mmol, 1.5 eq), and cesium carbonate (184 mg,
.56 mmol, 1 eq) were dissolved in anhydrous dioxane (7 mL) under a N atmosphere. A solution of RuPhos (13
mg, 0.028 mmol, 0.1 eq), palladium acetate (4 mg, 0.017 mmol, 0.05 eq) in anhydrous dioxane (2 mL) was
added dropwise. The mixture was heated to 80 °C and stirred under a N atmosphere. Upon completion of the
reaction (4-12 h), the mixture was cooled, diluted with EtOAc (50 mL), and filtered through celite. The filtrate
was washed with H O (50 mL), saturated NaHCO solution (50 mL), and brine (50 mL). The organic layer was
dried over MgSO , concentrated to dryness, and purified by column chromatography (hexanes/EtOAc gradient)
to yield the pure C4-substituted compound.
0
2
2
2
3
4
1
7
-(methoxymethoxy)-2,4-dimethylquinoline-8-carbonitrile (9f). (40 mg, 59% yield). H NMR (500 MHz
chloroform-d, δ): 8.08 (d, J = 9.3 Hz, 1H), 7.45 (d, J = 9.3 Hz, 1H), 7.11 (s, 1H), 5.44 (s, 2H), 3.58 (s, 3H), 2.72
13
(
1
s, 3H), 2.64 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.2, 161.4, 148.8, 144.4, 129.7, 122.6,
+
21.8, 115.2, 114.0, 99.8, 95.0, 56.8, 25.5, 18.4; HRMS (ESI-QTOF) m/z: [M + H] calcd for C14
H
15
N
2
2
O ,
243.1189; found, 243.1186.
7
-(methoxymethoxy)-2-methyl-4-(1-(triisopropylsilyl)-1H-pyrrol-3-yl)quinoline-8-carbonitrile (9g). (56 mg,
1
67% yield). H NMR (500 MHz, chloroform-d, δ): 8.46 (d, J = 9.4 Hz, 1H), 7.40 (d, J = 9.4 Hz, 1H), 7.25 (s,
1H), 7.05 (t, J = 1.7 Hz, 1H), 6.92 (t, J = 2.4 Hz, 1H), 6.59 (dd, J = 2.8, 1.4 Hz, 1H), 5.43 (s, 2H), 3.58 (s, 3H),
2.77 (s, 3H), 1.52 (hept, J = 7.5 Hz, 3H), 1.16 (d, J = 7.5 Hz, 18H); C NMR{1H} (126 MHz, chloroform-d, δ):
1
3
161.9, 161.4, 149.7, 143.6, 132.4, 125.5, 124.5, 122.4, 120.7, 120.6, 115.5, 113.7, 111.8, 99.5, 94.9, 56.8, 25.6,
+
17.8, 11.7; HRMS (ESI-QTOF) m/z: [M + H] calcd for C26
H
36
N
3
O
2
Si, 450.2571; found, 450.2571.
1
7
-(methoxymethoxy)-2-methyl-4-phenylquinoline-8-carbonitrile (9h). (36 mg, 50% yield). H NMR (500 MHz,
chloroform-d, δ): 8.01 (d, J = 9.4 Hz, 1H), 7.57 – 7.49 (m, 3H), 7.48 – 7.42 (m, 2H), 7.41 (d, J = 9.4 Hz, 1H),
1
3
7
.23 (s, 1H), 5.43 (s, 2H), 3.58 (s, 3H), 2.82 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 161.9, 161.7,
1
49.4, 148.7, 137.2, 131.9, 129.4, 128.7, 121.9, 120.4, 115.2, 114.4, 107.3, 99.7, 95.0, 56.8, 25.6; HRMS (ESI-
+
QTOF) m/z: [M + H] calcd for C19
H
17
N
2
2
O , 305.1285; found, 305.1272.
1
7
-(methoxymethoxy)-2-methyl-4-(p-tolyl)quinoline-8-carbonitrile (9i). (90 mg, 99% yield). H NMR (500
MHz, methanol-d , d): 7.98 (d, J = 9.5 Hz, 1H), 7.44 (d, J = 9.5 Hz, 1H), 7.36 – 7.28 (m, 4H), 7.22 (s, 1H), 5.46
4
1
3
(
s, 2H), 3.55 (s, 3H), 2.71 (s, 3H), 2.43 (s, 3H); C NMR{1H} (126 MHz, methanol-d
4
, d): 162.0, 161.9, 149.2,
1
48.9, 138.8, 133.9, 131.9, 129.1, 129.1, 121.6, 120.1, 114.5, 114.3, 98.2, 94.9, 55.7, 23.9, 19.9; HRMS (ESI-
+
QTOF) m/z: [M + H] calcd for C20
H
19
N
2
2
O , 319.1441; found, 319.1443.
1
7
-(methoxymethoxy)-4-(4-methoxyphenyl)-2-methylquinoline-8-carbonitrile (9j). (59 mg, 63% yield). H NMR
(
500 MHz, methanol-d , d): 8.13 (d, J = 9.4 Hz, 1H), 7.54 (d, J = 9.5 Hz, 1H), 7.50 – 7.40 (m, 2H), 7.32 (s, 1H),
.17 – 7.07 (m, 2H), 5.51 (s, 2H), 3.90 (s, 3H), 3.58 (s, 3H), 2.77 (s, 3H); C NMR{1H} (126 MHz, methanol-
4
1
3
7
d
5
4
, d): 163.2, 158.7, 149.6, 137.5, 135.5, 133.5, 130.7, 129.5, 127.8, 116.0, 114.8, 114.2, 113.9, 113.5, 77.3,
+
5.2, 53.5, 29.7; HRMS (ESI-QTOF) m/z: [M + H] calcd for C20
H
19
N
2
O
3
, 335.1390; found, 335.1398.
1
4
-(4-cyanophenyl)-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (9k). (50 mg, 54% yield). H NMR
(
5
500 MHz, chloroform-d, δ): 7.90 – 7.83 (m, 3H), 7.63 – 7.57 (m, 2H), 7.46 (d, J = 9.4 Hz, 1H), 7.22 (s, 1H),
.45 (s, 2H), 3.59 (s, 3H), 2.85 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.0, 161.9, 149.4, 146.5,
13
1
41.9, 132.5, 130.9, 130.2, 121.8, 119.6, 118.3, 115.1, 114.8, 112.9, 100.03, 95.0, 56.9, 25.7; HRMS (ESI-
+
QTOF) m/z: [M + H] calcd for C20
H
16
N
3
2
O , 330.1237; found, 330.1236.
1
tert-butyl 4-(8-cyano-7-(methoxymethoxy)-2-methylquinolin-4-yl)benzoate (9l). (68 mg, 60% yield). H NMR
(500 MHz, chloroform-d, δ): 8.16 (d, J = 7.9 Hz, 2H), 7.94 (d, J = 9.4 Hz, 1H), 7.52 (d, J = 7.9 Hz, 2H), 7.42 (d,
1
3
J = 9.4 Hz, 1H), 7.23 (s, 1H), 5.44 (s, 2H), 3.59 (s, 3H), 2.84 (s, 3H), 1.66 (s, 9H); C NMR{1H} (126 MHz,
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chloroform-d, δ): 165.2, 162.0, 161.8, 149.3, 147.8, 141.2, 132.4, 131.5, 129.8, 129.3, 121.8, 120.0, 115.0,
+
114.7, 99.8, 95.0, 81.6, 56.9, 28.2, 25.7; HRMS (ESI-QTOF) m/z: [M + H] calcd for C24
H
25
N
2
O
4
, 405.1809;
found, 405.1814.
1
4-(4-fluorophenyl)-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (9m). (90 mg, 99% yield). H NMR
(500 MHz, chloroform-d, δ): 7.97 (d, J = 9.4 Hz, 1H), 7.48 – 7.38 (m, 3H), 7.23 (dd, J = 16.4, 7.8 Hz, 3H), 5.44
1
3
1
(s, 2H), 3.58 (s, 3H), 2.81 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 164.1 ( JC–F = 249.5 Hz), 162.0,
4
3
2
0
1
2
3
4
5
6
7
8
9
0
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0
1
2
3
4
5
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7
8
9
0
1
2
3
4
5
6
7
8
9
0
161.7, 149.4, 147.7, 133.1 ( JC–F = 3.8 Hz), 131.6, 131.1 ( JC–F = 8.6 Hz), 122.0, 120.3, 115.9 ( JC–F = 21.6 Hz),
115.1, 114.6, 99.7, 95.0, 56.9, 25.6; HRMS (ESI-QTOF) m/z: [M + H] calcd for C19
+
H
16FN
2
2
O , 323.1190;
found, 323.1188.
4
-(4-(dimethylamino)phenyl)-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (9n). (49 mg, 51% yield).
1
H NMR (500 MHz, methanol-d
.31 (s, 1H), 6.97 – 6.90 (m, 2H), 5.51 (s, 2H), 3.59 (s, 3H), 3.06 (s, 6H), 2.77 (s, 3H); C NMR{1H} (126
MHz, chloroform-d, δ): 166.0, 159.9, 157.6, 151.2, 146.2, 132.5, 130.2, 127.3, 125.8, 119.8, 114.0, 112.1,
4
, d): 8.24 (d, J = 9.5 Hz, 1H), 7.54 (d, J = 9.5 Hz, 1H), 7.46 – 7.37 (m, 2H),
1
3
7
+
104.5, 98.3, 94.9, 55.7, 39.1, 23.8; HRMS (ESI-QTOF) m/z: [M + H] calcd for C21
H
22
N
3
O
2
, 348.1935; found,
348.1933.
1
7
-(methoxymethoxy)-2-methyl-4-(m-tolyl)quinoline-8-carbonitrile (9o). (81 mg, 91% yield). H NMR (500
MHz, chloroform-d, δ): 8.03 (d, J = 9.4 Hz, 1H), 7.46 – 7.38 (m, 2H), 7.33 (d, J = 7.7 Hz, 1H), 7.30 – 7.23 (m,
1
3
2
H), 7.22 (s, 1H), 5.44 (s, 2H), 3.59 (s, 3H), 2.82 (s, 3H), 2.46 (s, 3H); C NMR{1H} (126 MHz, chloroform-d,
δ): 161.9, 161.7, 149.3, 148.9, 138.5, 137.1, 132.0, 130.0, 129.5, 128.6, 126.5, 121.9, 120.4, 115.2, 114.3, 99.6,
+
9
5.0, 56.8, 25.6, 21.5; HRMS (ESI-QTOF) m/z: [M + H] calcd for C20
H
19
N
2
O
2
, 319.1441; found, 319.1441.
1
7
-(methoxymethoxy)-4-(3-methoxyphenyl)-2-methylquinoline-8-carbonitrile (9p). (93 mg, 99% yield). H
NMR (500 MHz, chloroform-d, δ): 8.04 (d, J = 9.4 Hz, 1H), 7.51 – 7.34 (m, 2H), 7.23 (s, 1H), 7.10 – 7.00 (m,
13
2
H), 6.98 (dd, J = 2.6, 1.6 Hz, 1H), 5.44 (s, 2H), 3.88 (s, 3H), 3.58 (s, 3H), 2.82 (s, 3H); C NMR{1H} (126
MHz, chloroform-d, δ ): 161.9, 161.7, 159.8, 149.3, 148.6, 138.5, 131.9, 129.8, 122.5, 121.8, 120.4, 115.2,
+
115.1, 114.4, 114.2, 99.6, 95.0, 56.8, 55.4, 25.6; HRMS (ESI-QTOF) m/z: [M + H] calcd for C20
H
19
N
2
3
O ,
335.1390; found, 335.1399.
1
4-(3-fluorophenyl)-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (9q). (83 mg, 92% yield). H NMR
(500 MHz, chloroform-d, δ): 7.96 (d, J = 9.4 Hz, 1H), 7.51 (td, J = 7.9, 5.7 Hz, 1H), 7.42 (d, J = 9.4 Hz, 1H),
1
3
7.23 (d, J = 8.1 Hz, 2H), 7.20 – 7.12 (m, 2H), 5.43 (s, 2H), 3.57 (s, 3H), 2.80 (s, 3H); C NMR{1H} (126 MHz,
1
7
chloroform-d, δ): 162.7 ( JC–F = 247.6 Hz), 162.0, 161.7, 149.28, 147.3 ( JC–F = 1.8 Hz (Position 4 of
4
3
5
quinoline)), 139.2 ( JC–F = 7.3 Hz), 131.5, 130.5 ( JC–F = 8.4 Hz), 125.2 ( JC–F = 3.25 Hz), 121.8, 120.0, 116.5
2
6
( JC–F = 21.6 Hz), 115.7 ( JC–F = 20.8 Hz), 115.0, 114.7, 99.7, 95.0, 56.8, 25.6; HRMS (ESI-QTOF) m/z: [M +
+
H] calcd for C19
H16FN
2
O
2
, 323.1190; found, 323.1197.
4
-(3-(dimethylamino)phenyl)-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (9r). (79 mg, 82% yield).
1
H NMR (500 MHz, chloroform-d, δ): 8.11 (d, J = 9.3 Hz, 1H), 7.42 – 7.34 (m, 2H), 7.25 (s, 1H), 6.86 (dd, J =
1
3
8.5, 2.7 Hz, 1H), 6.76 (t, J = 5.9 Hz, 2H), 5.44 (s, 2H), 3.59 (s, 3H), 3.03 (s, 6H), 2.82 (s, 3H); C NMR{1H}
(
1
126 MHz, chloroform-d, δ): 161.9, 161.6, 150.6, 149.8, 149.3, 138.0, 132.3, 129.3, 121.8, 120.7, 117.5, 115.3,
+
14.2, 113.2, 112.6, 99.5, 95.0, 56.8, 40.5, 25.7; HRMS (ESI-QTOF) m/z: [M + H] calcd for C21
H
22
N
3
2
O ,
348.1707; found, 348.1685.
1
4-(3,5-dimethoxyphenyl)-7-(methoxymethoxy)-2-methylquinoline-8-carbonitrile (9s). (92 mg, 90% yield). H
NMR (500 MHz, chloroform-d, δ): 8.07 (d, J = 9.4 Hz, 1H), 7.41 (d, J = 9.5 Hz, 1H), 7.23 (s, 1H), 6.63 – 6.57
13
(
m, 2H), 6.57 (s, 1H), 5.44 (s, 2H), 3.86 (s, 6H), 3.59 (s, 3H), 2.82 (s, 3H); C NMR{1H} (126 MHz,
chloroform-d, δ): 161.9, 161.7, 160.9, 149.3, 148.7, 139.1, 132.0, 121.6, 120.3, 115.2, 114.4, 111.0, 108.4,
+
1
07.6, 100.5, 99.5, 95.0, 94.3, 56.8, 55.6, 25.6; HRMS (ESI-QTOF) m/z: [M + H] calcd for C21
H
21
N
2
4
O ,
365.1496; found, 365.1478.
1
7-(methoxymethoxy)-2-methyl-4-(3,4,5-trimethoxyphenyl)quinoline-8-carbonitrile (9t). (80 mg, 72% yield). H
NMR (500 MHz, chloroform-d, δ): 8.09 (d, J = 9.3 Hz, 1H), 7.44 (d, J = 9.4 Hz, 1H), 7.24 (s, 1H), 6.66 (s, 2H),
1
3
5.45 (s, 2H), 3.97 (s, 3H), 3.91 (s, 6H), 3.60 (s, 3H), 2.83 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ):
162.0, 161.7, 153.8, 153.4, 149.4, 148.8, 138.4, 132.7, 131.9, 121.7, 120.4, 115.2, 114.4, 106.6, 99.6, 95.0, 93.0,
+
61.1, 56.9, 56.3, 56.0, 25.7; HRMS (ESI-QTOF) m/z: [M + H] calcd for C22
H
23
N
2
5
O , 395.1601; found,
395.1608.
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General procedure for the preparation of primary alcohols 10a-v
To a suspension of selenium dioxide (0.9 mmol, 3 eq) in dioxane (8 mL), a 70% tert-butyl hydroperoxide
solution (0.3 mmol, 1 eq) in H O was added, and the mixture was stirred at 50 °C for 15 min. A solution of one
2
of the quinolines 9a-t (0.3 mmol, 1 eq) in dioxane (2 mL) was added dropwise. The mixture was heated to 70
°C and stirred until competition of the reaction (1-12 h), monitoring by LC-MS. After cooling, the reaction
mixture was diluted with EtOAc (60 mL) and filtered through celite. The filtrate was washed with H
2
O (30 mL),
saturated NaHCO solution (30 mL), and brine (30 mL). The organic layer was dried over MgSO and
3
4
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9
0
concentrated to a dry residue that was dissolved in ethanol (10 mL). Sodium borohydride (0.9 mmol, 3 eq) was
added in small portions, and the mixture was stirred at room temperature for 6 h. The solvent was evaporated
under vacuum, and the residue was dissolved in EtOAc (50 mL), and the resulting solution was washed with
H
2
O (3 × 30 mL) and brine (30 mL), dried over MgSO
4
, concentrated to dryness, and purified by column
chromatography (hexanes/EtOAc gradient) to yield the respective pure primary alcohol 10a-v.
1
4-chloro-2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-8-carbonitrile (10a). (130 mg, 42% yield). H NMR
(
(
500 MHz, chloroform-d, δ): 8.30 (d, J = 9.4 Hz, 1H), 7.59 (d, J = 9.5 Hz, 1H), 7.44 (s, 1H), 5.48 (s, 2H), 4.93
s, 2H), 3.59 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 163.0, 162.7, 148.3, 143.5, 130.2, 120.7,
1
3
+
118.2, 116.0, 114.1, 99.4, 95.2, 64.2, 57.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for C13
H
12ClN
2
3
O ,
279.0531; found, 279.0534.
1
2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-4,8-dicarbonitrile (10b). (10 mg, 11% yield). H NMR (500
MHz, chloroform-d, δ): 8.35 (d, J = 9.3 Hz, 1H), 7.81 – 7.74 (m, 2H), 7.47 – 7.39 (m, 1H), 5.53 (s, 2H), 5.06 (d,
13
J = 3.2 Hz, 2H), 3.62 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 163.2, 162.7, 147.6, 130.7, 122.0,
+
120.3, 119.8, 117.7, 114.7, 113.5, 113.2, 95.3, 64.5, 57.2; HRMS (ESI-QTOF) m/z: [M + H] calcd for
C
14
H
12
N
3
O
3
, 270.0873; found, 270.0859.
4
-(dimethylamino)-2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-8-carbonitrile (10c). (50 mg, 31% yield).
1
H NMR (500 MHz, chloroform-d, δ): 8.19 (d, J = 9.4 Hz, 1H), 7.40 (d, J = 9.4 Hz, 1H), 6.60 (s, 1H), 5.46 (s,
2H), 4.85 (s, 2H), 4.46 (s, 1H), 3.60 (s, 3H), 3.08 (s, 6H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.1,
1
3
161.5, 158.3, 149.6, 130.8, 117.4, 114.8, 112.5, 103.4, 99.6, 94.9, 67.1, 64.1, 53.4, 43.9; HRMS (ESI-QTOF)
+
m/z: [M + H] calcd for C15
H
18
N
3
3
O , 288.1343; found, 288.1365.
1
2-(hydroxymethyl)-7-(methoxymethoxy)-4-morpholinoquinoline-8-carbonitrile (10d). (12 mg, 30% yield). H
NMR (500 MHz, chloroform-d, δ): 8.15 (d, J = 9.4 Hz, 1H), 7.46 (d, J = 9.5 Hz, 1H), 6.75 (s, 1H), 5.46 (s, 2H),
1
3
4.88 (s, 2H), 4.38 (s, 1H), 3.99 (t, J = 4.6 Hz, 4H), 3.60 (s, 3H), 3.24 (t, J = 4.6 Hz, 4H); C NMR{1H} (126
MHz, chloroform-d, δ): 162.9, 161.8, 157.8, 149.2, 129.8, 117.9, 114.6, 113.7, 105.4, 99.8, 95.0, 66.7, 64.3,
+
5
6.9, 52.8; HRMS (ESI-QTOF) m/z: [M + H] calcd for C17
H
20
N
3
O
4
, 330.1448; found, 330.1437.
2
-(hydroxymethyl)-7-(methoxymethoxy)-4-(phenylethynyl)quinoline-8-carbonitrile (10e). (30 mg, 59% yield).
1
H NMR (500 MHz, chloroform-d, δ): 8.52 (d, J = 9.3 Hz, 1H), 7.70 – 7.60 (m, 3H), 7.50 – 7.45 (m, 4H), 5.50
1
3
(d, J = 2.8 Hz, 2H), 4.98 (s, 2H), 4.25 (s, 1H), 3.61 (d, J = 2.6 Hz, 3H); C NMR{1H} (126 MHz, chloroform-
d, δ): 162.4, 161.8, 147.5, 132.1, 132.0, 131.0, 129.9, 128.7, 122.3, 121.6, 120.4, 115.6, 114.3, 99.9, 99.6, 95.1,
+
8
4.1, 64.1, 57.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for C21
H
17
N
2
O
3
, 345.1234; found, 345.1207.
1
2-(hydroxymethyl)-7-(methoxymethoxy)-4-methylquinoline-8-carbonitrile (10f). (81 mg, 47% yield). H NMR
(
500 MHz, chloroform-d, δ): 8.15 (d, J = 9.4 Hz, 1H), 7.54 (d, J = 9.4 Hz, 1H), 7.13 (s, 1H), 5.47 (s, 2H), 4.90
13
(d, J = 4.4 Hz, 2H), 3.60 (s, 3H), 2.71 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 161.9, 161.7, 147.4,
+
145.7, 123.0, 122.8, 118.7, 114.8, 114.6, 99.7, 95.0, 64.0, 56.9, 18.7; HRMS (ESI-QTOF) m/z: [M + H] calcd
for C14
H
15
N
2
O
3
, 259.1077; found, 259.1048.
2
-(hydroxymethyl)-7-(methoxymethoxy)-4-(1-(triisopropylsilyl)-1H-pyrrol-3-yl)quinoline-8-carbonitrile (10g).
1
(12 mg, 43% yield). H NMR (500 MHz, chloroform-d, δ): 8.54 (dd, J = 9.5, 3.8 Hz, 1H), 7.50 (dd, J = 9.4, 3.8
Hz, 1H), 7.29 – 7.25 (m, 1H), 7.10 (s, 1H), 6.96 (s, 1H), 6.63 (s, 1H), 5.48 (d, J = 3.8 Hz, 2H), 4.96 (d, J = 3.8
Hz, 2H), 4.51 (s, 1H), 3.62 (d, J = 3.9 Hz, 3H), 1.54 (dq, J = 14.9, 6.8, 5.4 Hz, 3H), 1.18 (dd, J = 7.6, 3.8 Hz,
1
3
18H); C NMR{1H} (126 MHz, chloroform-d, δ): 161.7, 161.5, 148.4, 144.7, 132.7, 125.7, 124.7, 122.3,
+
121.6, 116.8, 114.9, 114.4, 111.8, 99.4, 94.9, 64.1, 56.9, 17.8, 11.6; HRMS (ESI-QTOF) m/z: [M + H] calcd
for C26
H
36
N
3
3
O Si, 466.2520; found, 466.2520.
1
2-(hydroxymethyl)-7-(methoxymethoxy)-4-phenylquinoline-8-carbonitrile (10h). (23 mg, 40% yield). H NMR
(
5
500 MHz, chloroform-d, δ): 8.08 (d, J = 9.5 Hz, 1H), 7.61 – 7.51 (m, 3H), 7.51 – 7.43 (m, 3H), 7.26 (s, 1H),
.47 (s, 2H), 5.00 (s, 2H), 3.60 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.0, 161.8, 149.8, 148.1,
1
3
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36.9, 132.2, 129.4, 129.1, 128.9, 121.5, 118.2, 115.1, 114.5, 99.6, 95.0, 64.2, 56.9; HRMS (ESI-QTOF) m/z:
+
[M + H] calcd for C19
H
17
N
2
3
O , 321.1234; found, 321.1232.
1
2-(hydroxymethyl)-7-(methoxymethoxy)-4-(p-tolyl)quinoline-8-carbonitrile (10i). (28 mg, 84% yield). H NMR
(500 MHz, methanol-d , d): 8.13 (d, J = 9.5 Hz, 1H), 7.61 – 7.54 (m, 2H), 7.44 – 7.38 (m, 4H), 5.51 (s, 2H),
.92 (s, 2H), 3.58 (s, 3H), 2.47 (s, 3H); C NMR{1H} (126 MHz, methanol-d
138.9, 134.2, 132.2, 129.2, 129.1, 121.0, 118.2, 114.9, 114.4, 98.4, 94.9, 64.8, 55.7, 19.91; HRMS (ESI-QTOF)
4
1
3
4
4
, d): 164.2, 162.2, 150.0, 148.5,
+
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
m/z: [M + H] calcd for C20
H
19
N
2
O
3
, 335.1390; found, 335.1390.
2-(hydroxymethyl)-7-(methoxymethoxy)-4-(4-methoxyphenyl)quinoline-8-carbonitrile (10j). (22 mg, 41%
1
yield). H NMR (500 MHz, methanol-d
5.51 (s, 2H), 4.92 (s, 2H), 3.58 (s, 3H), 2.47 (s, 3H); C NMR{1H} (126 MHz, methanol-d
150.0, 148.5, 138.9, 134.2, 132.2, 129.2, 129.1, 121.0, 118.2, 114.9, 114.4, 98.4, 94.9, 64.8, 55.7, 19.91; HRMS
4
, d): 8.13 (d, J = 9.5 Hz, 1H), 7.61 – 7.54 (m, 2H), 7.44 – 7.38 (m, 4H),
1
3
4
, d): 164.2, 162.2,
+
(ESI-QTOF) m/z: [M + H] calcd for C20
H
19
N
2
O
4
, 351.1339; found, 351.1330.
4
-(4-cyanophenyl)-2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-8-carbonitrile (10k). (17 mg, 25% yield).
1
H NMR (500 MHz, DMSO-d
6
, d) 8.11 – 8.06 (m, 2H), 8.01 (d, J = 9.5 Hz, 1H), 7.80 – 7.75 (m, 2H), 7.66 (d, J
1
3
= 9.6 Hz, 1H), 7.63 (s, 1H), 5.55 (s, 2H), 4.82 (s, 2H), 3.48 (s, 3H); C NMR{1H} (126 MHz, DMSO-d
6
, d):
65.8, 162.4, 148.5, 147.6, 142.0, 133.3, 132.3, 130.9, 120.3, 119.1, 119.0, 116.5, 115.2, 112.2, 98.7, 95.3, 65.1,
6.8; HRMS (ESI-QTOF) m/z: [M + H] calcd for C20
1
5
+
H
16
N
3
3
O , 346.1186; found, 346.1186.
tert-butyl 4-(8-cyano-2-(hydroxymethyl)-7-(methoxymethoxy)quinolin-4-yl)benzoate (10l). (16 mg, 30% yield).
1
H NMR (500 MHz, chloroform-d, δ): 8.21 – 8.15 (m, 2H), 8.00 (d, J = 9.4 Hz, 1H), 7.56 – 7.47 (m, 3H), 7.26
1
3
(s, 1H), 5.47 (s, 2H), 5.02 (d, J = 4.6 Hz, 2H), 4.33 (t, J = 4.8 Hz, 1H), 3.60 (s, 3H), 1.67 (s, 9H); C NMR{1H}
(126 MHz, chloroform-d, δ): 165.1, 162.1, 161.8, 148.8, 148.1, 140.8, 132.7, 131.8, 129.9, 129.3, 121.1, 118.1,
+
115.4, 114.4, 99.8, 95.0, 81.7, 64.3, 57.0, 28.2; HRMS (ESI-QTOF) m/z: [M + H] calcd for C24
H
25
N
2
5
O ,
421.1758; found, 421.1790.
4
-(4-fluorophenyl)-2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-8-carbonitrile (10m). (16 mg, 25% yield).
1
H NMR (500 MHz, chloroform-d, δ): 8.03 (d, J = 9.4 Hz, 1H), 7.53 – 7.43 (m, 3H), 7.27 (dd, J = 13.6, 5.1 Hz,
13
3
H), 5.46 (s, 2H), 4.99 (s, 2H), 4.36 (s, 1H), 3.59 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 163.2
1
4
3
( JC–F = 249.4 Hz), 162.0, 161.9, 148.71, 148.11, 132.8 ( JC–F = 3.7 Hz), 131.9, 131.2 ( JC–F = 8.6 Hz), 121.4,
2
+
118.3, 116.1 ( JC–F = 21.8 Hz), 115.3, 114.5, 99.6, 95.0, 64.3, 56.9; HRMS (ESI-QTOF) m/z: [M + H] calcd for
C
19
H16FN
2
O
3
, 339.1139; found, 339.1140.
4-(4-(dimethylamino)phenyl)-2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-8-carbonitrile (10n). (10 mg,
1
32% yield). H NMR (500 MHz, chloroform-d, δ): 8.24 (d, J = 9.4 Hz, 1H), 7.46 (d, J = 9.5 Hz, 1H), 7.39 (d, J
= 8.5 Hz, 2H), 7.20 (s, 1H), 6.86 (d, J = 8.7 Hz, 2H), 5.47 (s, 2H), 4.97 (s, 2H), 3.61 (s, 3H), 3.08 (s, 6H); C
NMR{1H} (126 MHz, chloroform-d, δ): 161.8, 161.5, 150.9, 150.2, 148.3, 132.7, 130.7, 130.5, 124.1, 121.8,
117.7, 114.8, 114.5, 112.1, 99.4, 95.0, 64.2, 56.9, 40.3; HRMS (ESI-QTOF) m/z: [M + H] calcd for
C
1
3
+
21
H
22
N
3
3
O , 364.1656; found, 364.1654.
1
2-(hydroxymethyl)-7-(methoxymethoxy)-4-(m-tolyl)quinoline-8-carbonitrile (10o). (18 mg, 60% yield). H
NMR (500 MHz, chloroform-d, δ): 8.09 (d, J = 9.4 Hz, 1H), 7.48 (d, J = 9.5 Hz, 1H), 7.44 (t, J = 7.6 Hz, 1H),
1
3
7.35 (d, J = 7.7 Hz, 1H), 7.30 – 7.23 (m, 3H), 5.46 (s, 2H), 4.99 (s, 2H), 3.59 (s, 3H), 2.47 (s, 3H); C
NMR{1H} (126 MHz, chloroform-d, δ): 161.9, 161.7, 150.0, 148.1, 138.7, 136.8, 132.4, 130.0, 129.8, 128.7,
+
126.5, 121.5, 118.2, 115.0, 114.6, 99.5, 95.0, 64.2, 56.9, 21.5; HRMS (ESI-QTOF) m/z: [M + H] calcd for
C
20
H
19
N
2
O
3
, 335.1390; found, 335.1390.
2-(hydroxymethyl)-7-(methoxymethoxy)-4-(3-methoxyphenyl)quinoline-8-carbonitrile (10p). (20 mg, 38%
1
yield). H NMR (500 MHz, chloroform-d, δ): 8.10 (d, J = 9.4 Hz, 1H), 7.51 – 7.43 (m, 2H), 7.26 (s, 1H), 7.10 –
7
3
1
.01 (m, 2H), 6.99 (t, J = 2.1 Hz, 1H), 5.46 (s, 2H), 5.00 (d, J = 4.0 Hz, 2H), 4.39 (t, J = 4.9 Hz, 1H), 3.89 (s,
H), 3.60 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.0, 161.8, 159.8, 149.7, 148.0, 138.2, 132.3,
29.9, 121.7, 121.4, 118.1, 115.1, 115.1, 114.6, 114.4, 99.5, 95.0, 64.3, 56.9, 55.5; HRMS (ESI-QTOF) m/z: [M
13
+
+
H] calcd for C20
H
19
N
2
4
O , 351.1339; found, 351.1331.
4
-(3-fluorophenyl)-2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-8-carbonitrile (10q). (30 mg, 34% yield).
1
H NMR (500 MHz, chloroform-d, δ): 8.03 (d, J = 9.4 Hz, 1H), 7.53 (dt, J = 14.2, 8.5 Hz, 2H), 7.30 – 7.15 (m,
13
4
H), 5.46 (s, 2H), 4.99 (s, 2H), 4.35 (s, 1H), 3.58 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.7
1
7
4
( JC–F = 248.1 Hz), 162.1, 162.0, 148.3 ( JC–F = 1.7 Hz (Position 4 of quinoline)), 148.1, 138.8 ( JC–F = 7.6 Hz),
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31.82, 130.6 (3JC–F = 8.4 Hz), 125.2 (5JC–F = 2.8 Hz), 121.1, 118.2, 116.5 ( JC–F = 22.4 Hz), 116.1 (6JC–F = 20.9
2
1
+
Hz), 115.4, 114.5, 99.6, 95.1, 64.3, 56.9; HRMS (ESI-QTOF) m/z: [M + H] calcd for C19
H16FN
2
3
O , 339.1139;
found, 339.1140.
4-(3-(dimethylamino)phenyl)-2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-8-carbonitrile (10r). (15 mg,
1
29% yield). H NMR (500 MHz, chloroform-d, δ): 8.17 (d, J = 9.4 Hz, 1H), 7.47 (d, J = 9.4 Hz, 1H), 7.39 (dd, J
= 8.4, 7.4 Hz, 1H), 7.26 (s, 1H), 6.88 (dd, J = 8.3, 2.6 Hz, 1H), 6.80 – 6.73 (m, 2H), 5.47 (s, 2H), 5.00 (d, J =
1
3
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
4.3 Hz, 2H), 4.44 (t, J = 4.8 Hz, 1H), 3.61 (s, 3H), 3.03 (s, 6H); C NMR{1H} (126 MHz, chloroform-d, δ):
161.9, 161.6, 150.9, 150.6, 148.0, 137.7, 132.6, 129.4, 121.8, 118.0, 117.4, 114.9, 114.7, 113.0, 112.8, 99.5,
+
9
5.0, 64.2, 56.9, 40.5; HRMS (ESI-QTOF) m/z: [M + H] calcd for C21
H
22
N
3
3
O , 364.1656; found, 364.1622.
4
-(3,5-dimethoxyphenyl)-2-(hydroxymethyl)-7-(methoxymethoxy)quinoline-8-carbonitrile (10s). (22 mg, 45%
1
yield). H NMR (500 MHz, chloroform-d, δ): 8.13 (d, J = 9.4 Hz, 1H), 7.48 (d, J = 9.5 Hz, 1H), 7.26 (s, 1H),
6
3
1
.61 (t, J = 2.3 Hz, 1H), 6.58 (d, J = 2.3 Hz, 2H), 5.46 (s, 2H), 4.99 (s, 2H), 4.38 (s, 1H), 3.86 (s, 6H), 3.59 (s,
1
3
H); C NMR{1H} (126 MHz, chloroform-d, δ): 162.0, 161.8, 161.0, 149.8, 148.0, 138.7, 132.3, 121.4, 118.0,
+
15.1, 114.6, 107.6, 100.7, 99.5, 95.0, 64.3, 56.9, 55.6; HRMS (ESI-QTOF) m/z: [M + H] calcd for
C
21
H
21
N
2
5
O , 381.1445; found, 381.1441.
2
4
1
-(hydroxymethyl)-7-(methoxymethoxy)-4-(3,4,5-trimethoxyphenyl)quinoline-8-carbonitrile (10t). (55 mg,
1
5% yield). H NMR (500 MHz, chloroform-d, δ): 8.14 (d, J = 9.5 Hz, 1H), 7.51 (d, J = 9.5 Hz, 1H), 7.27 (s,
13
H), 6.67 (s, 2H), 5.47 (s, 2H), 4.99 (s, 2H), 3.96 (s, 3H), 3.91 (s, 6H), 3.60 (s, 3H); C NMR{1H} (126 MHz,
chloroform-d, δ): 162.0, 161.7, 153.5, 149.8, 148.1, 138.6, 132.4, 132.3, 121.5, 118.1, 115.1, 114.6, 106.6, 99.5,
+
9
5.0, 64.3, 61.1, 57.0, 56.4; HRMS (ESI-QTOF) m/z: [M + H] calcd for C22
H
23
N
2
6
O , 411.1551; found,
411.1557.
N-(4-(8-cyano-2-(hydroxymethyl)-7-(methoxymethoxy)quinolin-4-yl)phenyl)-N-methylformamide (10u). (10
mg, 23% yield). The crude product was carried forward to the next step without further purification. HRMS
+
(ESI-QTOF) m/z: [M + H] calcd for C21
H
20
N
3
4
O , 378.1448; found, 378.1427.
N-(3-(8-cyano-2-(hydroxymethyl)-7-(methoxymethoxy)quinolin-4-yl)phenyl)-N-methylformamide (10v). (8
mg, 16% yield). The crude product was carried forward to the next step without further purification. HRMS
+
(ESI-QTOF) m/z: [M + H] calcd for C21
H
20
N
3
4
O , 378.1448; found, 378.1414.
General procedure for the preparation of MOM-protected acetates 11a-v
To a solution of one of the primary alcohols 10a-v (0.1 mmol, 1 eq) in CH
2
2
Cl (5 mL), pyridine (0.5 mmol, 5
eq) and 4-dimethylaminopyridine (0.1 mmol, 1 eq) were added. The mixture was cooled to 0 °C with an ice-
bath, and acetic anhydride (0.4 mmol, 4 eq) was added dropwise. The mixture was stirred at 0 °C for 30 min,
then at room temperature for 6 h. The reaction mixture was diluted with CH
solution was washed with a saturated ammonium chloride solution (10 mL) and H
MgSO , and concentrated to dryness. The resulting crude product was purified by column chromatography
hexanes/EtOAc gradient) to yield the respective MOM-protected acetate 11a-v.
2
Cl
2
(20 mL) and the resulting
2
O (2 × 10 mL), dried over
4
(
1
(
4-chloro-8-cyano-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11a). (15 mg, 45% yield). H NMR (500
, d): 9.09 (d, J = 9.3 Hz, 1H), 8.41 (s, 1H), 8.29 – 8.24 (m, 1H), 6.12 (s, 2H), 3.96 – 3.95 (m,
MHz, methanol-d
4
1
3
3H), 2.98 (s, 3H), 2.03 (s, 2H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.6, 162.8, 159.5, 149.1, 143.7,
+
1
C
30.1, 120.9, 118.6, 116.4, 114.1, 100.1, 95.1, 66.2, 57.0, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for
, 321.0637; found, 321.0632.
15
H14ClN
2
O
4
1
(
4,8-dicyano-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11b). (8 mg, 64% yield). H NMR (500 MHz,
chloroform-d, δ): 8.34 (d, J = 9.4 Hz, 1H), 7.78 (t, J = 4.7 Hz, 2H), 5.52 (s, 2H), 5.50 (s, 2H), 3.61 (s, 3H), 2.30
13
(
s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.5, 163.2, 159.3, 148.2, 130.5, 122.1, 120.2, 119.8,
+
1
18.1, 114.8, 113.5, 100.6, 95.3, 66.0, 57.2, 20.8; HRMS (ESI-QTOF) m/z: [M + H] calcd for C16
H
14
N
3
4
O ,
312.0979; found, 312.0966.
1
(8-cyano-4-(dimethylamino)-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11c). (30 mg, 96% yield). H
NMR (500 MHz, chloroform-d, δ): 8.17 (d, J = 9.4 Hz, 1H), 7.38 (d, J = 9.4 Hz, 1H), 6.74 (s, 1H), 5.44 (s, 2H),
1
3
5.36 (s, 2H), 3.59 (s, 3H), 3.08 (s, 6H), 2.27 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.9, 161.5,
159.0, 158.4, 150.6, 130.6, 117.1, 115.1, 112.7, 104.3, 100.0, 94.9, 67.1, 56.8, 43.9, 21.0; HRMS (ESI-QTOF)
+
m/z: [M + H] calcd for C17
H
20
N
3
4
O , 330.1448; found, 330.1464.
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2
2
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2
2
2
2
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3
3
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3
3
3
3
3
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5
5
5
6
1
(
(
(
8-cyano-7-(methoxymethoxy)-4-morpholinoquinolin-2-yl)methyl acetate (11d). (14 mg, 96% yield). H NMR
500 MHz, chloroform-d, δ): 8.14 (d, J = 9.4 Hz, 1H), 7.46 (d, J = 9.4 Hz, 1H), 6.87 (s, 1H), 5.45 (s, 2H), 5.39
s, 2H), 3.99 (t, J = 4.6 Hz, 4H), 3.58 (s, 3H), 3.24 (t, J = 4.6 Hz, 4H), 2.28 (s, 3H); C NMR{1H} (126 MHz,
chloroform-d, δ): 170.9, 161.8, 159.7, 157.9, 150.1, 129.6, 117.7, 114.8, 114.0, 106.1, 100.3, 94.9, 66.9, 66.7,
1
3
+
56.9, 52.7, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for C19
H
22
N
3
O , 372.1554; found, 372.1557.
5
1
(8-cyano-7-(methoxymethoxy)-4-(phenylethynyl)quinolin-2-yl)methyl acetate (11e). (7 mg, 62% yield). H
NMR (500 MHz, chloroform-d, δ): 8.51 (dd, J = 9.4, 1.1 Hz, 1H), 7.69 – 7.59 (m, 4H), 7.49 – 7.44 (m, 3H),
5.49 (s, 2H), 5.48 (s, 2H), 3.61 (s, 3H), 2.30 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.7, 162.5,
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
3
1
5
58.9, 148.3, 132.0, 131.9, 131.1, 129.8, 128.7, 122.2, 121.7, 120.9, 116.0, 114.4, 100.1, 99.8, 95.1, 84.2, 66.5,
+
6.9, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for C23
H
19
N
2
O
4
, 387.1339; found, 387.1376.
1
(
8-cyano-7-(methoxymethoxy)-4-methylquinolin-2-yl)methyl acetate (11f). (19 mg, 77% yield). H NMR (500
MHz, chloroform-d, δ): 8.15 (d, J = 9.3 Hz, 1H), 7.54 (d, J = 9.3 Hz, 1H), 7.27 (d, J = 12.5 Hz, 1H), 5.46 (s,
H), 5.42 (s, 2H), 3.59 (s, 3H), 2.72 (s, 3H), 2.28 (d, J = 0.9 Hz, 3H); C NMR{1H} (126 MHz, chloroform-d,
δ): 170.9, 161.8, 158.9, 148.4, 145.8, 129.8, 122.7, 119.3, 115.1, 114.8, 100.1, 94.9, 66.7, 56.9, 21.0, 18.8;
1
3
2
+
HRMS (ESI-QTOF) m/z: [M + H] calcd for C16
H
17
N
2
O
4
, 301.1183; found, 301.1185.
(
8-cyano-7-(methoxymethoxy)-4-(1-(triisopropylsilyl)-1H-pyrrol-3-yl)quinolin-2-yl)methyl acetate (11g). (14
mg, 92% yield). H NMR (500 MHz, chloroform-d, δ): 8.51 (d, J = 9.4 Hz, 1H), 7.49 (d, J = 9.5 Hz, 1H), 7.29
s, 1H), 7.09 (s, 1H), 6.96 (t, J = 2.5 Hz, 1H), 6.65 – 6.61 (m, 1H), 5.47 (s, 4H), 3.60 (s, 3H), 2.28 (s, 3H), 1.55
p, J = 7.5 Hz, 3H), 1.19 (d, J = 7.5 Hz, 18H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.9, 161.7, 158.5,
1
(
(
1
1
13
49.3, 144.8, 132.5, 125.7, 124.7, 122.4, 121.5, 117.5, 115.1, 114.7, 111.9, 99.9, 94.9, 66.9, 56.8, 29.7, 21.0,
+
7.8, 11.6; HRMS (ESI-QTOF) m/z: [M + H] calcd for C28
H
38
N
3
O
4
Si, 508.2626; found, 508.2586.
1
(
8-cyano-7-(methoxymethoxy)-4-phenylquinolin-2-yl)methyl acetate (11h). (15 mg, 21% yield). H NMR (600
MHz, chloroform-d, δ): 8.06 (d, J = 9.4 Hz, 1H), 7.60 – 7.53 (m, 3H), 7.52 – 7.45 (m, 3H), 7.37 (s, 1H), 5.51 (s,
2H), 5.46 (s, 2H), 3.59 (s, 3H), 2.28 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.8, 162.0, 158.7,
149.8, 148.9, 137.0, 132.0, 129.4, 129.0, 128.8, 121.4, 118.7, 115.5, 114.7, 100.1, 95.0, 66.7, 56.9, 21.0; HRMS
1
3
+
(ESI-QTOF) m/z: [M + H] calcd for C21
H
19
N
2
4
O , 363.1339; found, 363.1353.
1
(8-cyano-7-(methoxymethoxy)-4-(p-tolyl)quinolin-2-yl)methyl acetate (11i). (10 mg, 74% yield). H NMR (500
MHz, chloroform-d, δ): 8.09 (d, J = 9.5 Hz, 1H), 7.47 (d, J = 9.5 Hz, 1H), 7.36 (d, J = 12.1 Hz, 5H), 5.50 (s,
H), 5.46 (s, 2H), 3.59 (s, 3H), 2.49 (s, 3H), 2.27 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.8,
1
3
2
1
2
61.9, 158.7, 149.9, 149.0, 139.1, 134.1, 132.1, 129.5, 129.4, 121.5, 118.6, 115.3, 114.8, 100.0, 95.0, 67.0, 56.9,
+
9.3, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for C22
H
21
N
2
4
O , 377.1496; found, 377.1515.
1
(
8-cyano-7-(methoxymethoxy)-4-(4-methoxyphenyl)quinolin-2-yl)methyl acetate (11j). (10 mg, 70% yield). H
NMR (500 MHz, chloroform-d, δ): 8.11 (d, J = 9.5 Hz, 1H), 7.48 (d, J = 9.5 Hz, 1H), 7.45 – 7.39 (m, 2H), 7.34
s, 1H), 7.12 – 7.06 (m, 2H), 5.50 (s, 2H), 5.46 (s, 2H), 3.93 (s, 3H), 3.60 (s, 3H), 2.27 (s, 3H); C NMR{1H}
126 MHz, chloroform-d, δ): 170.8, 161.9, 160.3, 158.7, 149.6, 149.1, 132.1, 130.8, 129.3, 121.5, 118.6, 115.3,
1
3
(
(
1
3
+
14.8, 114.3, 100.1, 95.0, 66.8, 57.0, 55.5, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for C22
H
21
N
2
5
O ,
93.1445; found, 393.1458.
1
(
8-cyano-4-(4-cyanophenyl)-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11k). (6 mg, 66% yield). H
NMR (500 MHz, chloroform-d, δ): 7.93 – 7.85 (m, 3H), 7.64 – 7.58 (m, 2H), 7.53 (d, J = 9.5 Hz, 1H), 7.34 (s,
H), 5.52 (s, 2H), 5.47 (s, 2H), 3.60 (s, 3H), 2.28 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.7,
62.2, 158.9, 148.9, 147.6, 141.7, 132.6, 131.0, 130.2, 120.5, 118.5, 118.2, 116.1, 114.4, 113.1, 100.4, 95.0,
13
1
1
6
+
6.6, 57.0, 20.9; HRMS (ESI-QTOF) m/z: [M + H] calcd for C22
H
18
N
3
O , 388.1292; found, 388.1309.
4
tert-butyl 4-(2-(acetoxymethyl)-8-cyano-7-(methoxymethoxy)quinolin-4-yl)benzoate (11l). (5 mg, 60% yield).
H NMR (500 MHz, chloroform-d, δ): 8.21 – 8.15 (m, 2H), 7.98 (d, J = 9.4 Hz, 1H), 7.56 – 7.51 (m, 2H), 7.49
(d, J = 9.5 Hz, 1H), 7.36 (s, 1H), 5.52 (s, 2H), 5.46 (s, 2H), 3.60 (s, 3H), 2.28 (s, 3H), 1.67 (s, 9H); C
NMR{1H} (126 MHz, chloroform-d, δ): 170.8, 165.1, 162.17, 158.8, 148.9, 148.8, 141.0, 132.6, 131.6, 129.9,
129.3, 121.0, 118.5, 115.7, 114.6, 100.2, 95.0, 81.7, 66.7, 56.9, 28.2, 21.0; HRMS (ESI-QTOF) m/z: [M + H]+
1
1
3
calcd for C26
H
27
N
2
6
O , 463.1864; found, 463.1864.
1
(
8-cyano-4-(4-fluorophenyl)-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11m). (20 mg, 95% yield). H
NMR (500 MHz, chloroform-d, δ): 8.01 (d, J = 9.5 Hz, 1H), 7.51 – 7.44 (m, 3H), 7.34 (s, 1H), 7.29 – 7.23 (m,
H), 5.49 (s, 2H), 5.46 (s, 2H), 3.59 (s, 3H), 2.27 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.8,
1
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2
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63.2 (1JC–F = 249.3 Hz), 162.0, 158.7, 148.9, 148.7, 133.0 ( JC–F = 3.7 Hz), 131.7, 131.2 (3JC–F = 8.3 Hz), 121.3,
18.7, 116.0 ( JC–F = 21.8 Hz), 115.6, 114.7, 100.1, 95.0, 66.7, 56.9, 21.0; HRMS (ESI-QTOF) m/z: [M + H]+
2
calcd for C21
H
18FN , 381.1245; found, 381.1240.
2
O
4
(8-cyano-4-(4-(dimethylamino)phenyl)-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11n). (8 mg, 73%
yield). H NMR (500 MHz, chloroform-d, δ): 8.22 (d, J = 9.5 Hz, 1H), 7.46 (d, J = 9.5 Hz, 1H), 7.41 – 7.37 (m,
2H), 7.34 (s, 1H), 6.90 – 6.84 (m, 2H), 5.49 (s, 2H), 5.47 (s, 2H), 3.60 (s, 3H), 3.09 (s, 6H), 2.27 (s, 3H); C
NMR{1H} (126 MHz, chloroform-d, δ): 170.8, 161.8, 158.6, 150.9, 150.2, 149.2, 132.5, 130.6, 124.3, 121.7,
1
1
3
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
+
118.2, 115.0, 114.9, 112.1, 99.9, 94.9, 66.9, 56.9, 40.3, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for
C
23
H
24
N
3
4
O , 406.1761; found, 406.1747.
1
(
(
(
8-cyano-7-(methoxymethoxy)-4-(m-tolyl)quinolin-2-yl)methyl acetate (11o). (15 mg, 74% yield). H NMR
500 MHz, chloroform-d, δ): 8.07 (d, J = 9.5 Hz, 1H), 7.50 – 7.41 (m, 2H), 7.35 (d, J = 4.7 Hz, 2H), 7.30 – 7.24
m, 2H), 5.50 (s, 2H), 5.45 (s, 2H), 3.59 (s, 3H), 2.48 (s, 3H), 2.27 (s, 3H); C NMR{1H} (126 MHz,
chloroform-d, δ): 170.8, 161.9, 158.7, 150.0, 148.9, 138.7, 137.0, 132.1, 130.0, 129.7, 128.7, 126.5, 121.4,
1
3
+
1
C
18.6, 115.4, 114.8, 100.0, 95.0, 66.7, 56.9, 21.5, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for
22
H
21
N
2
O
4
, 377.1496; found, 377.1517.
1
(
8-cyano-7-(methoxymethoxy)-4-(3-methoxyphenyl)quinolin-2-yl)methyl acetate (11p). (19 mg, 85% yield). H
NMR (500 MHz, chloroform-d, δ): 8.08 (d, J = 9.5 Hz, 1H), 7.47 (t, J = 9.1 Hz, 2H), 7.29 (s, 1H), 7.06 (ddd, J
17.1, 7.9, 2.0 Hz, 2H), 6.99 (t, J = 2.0 Hz, 1H), 5.50 (s, 2H), 5.46 (s, 2H), 3.89 (s, 3H), 3.59 (s, 3H), 2.27 (s,
H); C NMR{1H} (126 MHz, chloroform-d, δ): 170. 8, 162.0, 159.8, 158.7, 149.7, 148.9, 138.3, 132.0, 129.9,
21.8, 121.3, 118.5, 115.5, 115.2, 114.7, 114.3, 100.0, 95.0, 66.7, 56.9, 55.5, 21.0; HRMS (ESI-QTOF) m/z: [M
=
3
1
+
13
+
H] calcd for C22
H
21
N
2
5
O , 393.1445; found, 393.1425.
1
(
8-cyano-4-(3-fluorophenyl)-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11q). (29 mg, 86% yield). H
NMR (500 MHz, chloroform-d, δ): 8.02 (d, J = 9.5 Hz, 1H), 7.58 – 7.50 (m, 2H), 7.50 (s, 1H), 7.30 – 7.21 (m,
2H), 7.19 (ddd, J = 9.2, 2.6, 1.6 Hz, 1H), 5.49 (s, 2H), 5.46 (s, 2H), 3.58 (s, 3H), 2.27 (s, 3H); C NMR{1H}
(126 MHz, chloroform-d, δ): 170.8, 162.8 ( JC–F = 248.4 Hz), 162.1, 158.8, 148.9, 148.3 ( JC–F = 1.8 Hz
(Position 4 of quinoline)), 139.5 ( JC–F = 7.6 Hz), 131.6, 130.6 ( JC–F = 8.5 Hz), 125.2 ( JC–F = 3.2 Hz), 121.0,
118.6, 116.5 ( JC–F = 22.2 Hz), 116.0 ( JC–F = 21.4 Hz), 115.8, 114.6, 100.1, 95.0, 66.6, 56.9, 20.9; HRMS (ESI-
1
3
1
7
4
3
5
2
6
+
QTOF) m/z: [M + H] calcd for C21
H18FN
2
O
4
, 381.1245; found, 381.1231.
(
8-cyano-4-(3-(dimethylamino)phenyl)-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11r). (5 mg, 62%
yield). H NMR (500 MHz, chloroform-d, δ): 8.15 (d, J = 9.4 Hz, 1H), 7.46 (d, J = 9.5 Hz, 1H), 7.43 – 7.37 (m,
H), 6.89 (dd, J = 8.9, 2.6 Hz, 1H), 6.81 – 6.73 (m, 2H), 5.51 (s, 2H), 5.46 (s, 2H), 3.60 (s, 3H), 3.04 (s, 6H),
.27 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.8, 161.9, 158.7, 150.9, 150.6, 140.1, 140.0,
1
2
2
1
1
3
37.9, 132.4, 129.4, 118.4, 117.5, 115.2, 114.9, 113.1, 112.7, 95.0, 90.2, 66.8, 56.9, 40.5, 21.0; HRMS (ESI-
+
QTOF) m/z: [M + H] calcd for C23
H
24
N
3
O , 406.1761; found, 406.1759.
4
(
8-cyano-4-(3,5-dimethoxyphenyl)-7-(methoxymethoxy)quinolin-2-yl)methyl acetate (11s). (22 mg, 90% yield).
H NMR (500 MHz, chloroform-d, δ): 8.10 (d, J = 9.5 Hz, 1H), 7.48 (d, J = 9.5 Hz, 1H), 7.36 (s, 1H), 6.62 (t, J
2.3 Hz, 1H), 6.58 (d, J = 2.2 Hz, 2H), 5.50 (s, 2H), 5.46 (s, 2H), 3.87 (s, 6H), 3.59 (s, 3H), 2.27 (s, 3H); C
NMR{1H} (126 MHz, chloroform-d, δ): 170.8, 162.0, 161.0, 158.7, 149.8, 148.8, 138.9, 132.1, 121.3, 118.3,
1
1
3
=
+
1
C
15.4, 114.7, 107.7, 100.6, 100.0, 95.0, 66.7, 56.9, 55.6, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for
23
H
23
N
2
O
6
, 423.1551; found, 423.1558.
(
8-cyano-7-(methoxymethoxy)-4-(3,4,5-trimethoxyphenyl)quinolin-2-yl)methyl acetate (11t). (15 mg, 92%
yield). H NMR (500 MHz, chloroform-d, δ): 8.11 (d, J = 9.5 Hz, 1H), 7.50 (d, J = 9.5 Hz, 1H), 7.36 (s, 1H),
.66 (s, 2H), 5.50 (s, 2H), 5.46 (s, 2H), 3.97 (s, 3H), 3.91 (s, 6H), 3.59 (s, 3H), 2.28 (s, 3H); C NMR{1H} (126
MHz, chloroform-d, δ): 170.8, 162.0, 158.7, 153.5, 149.8, 148.9, 138.5, 132.5, 132.0, 121.4, 118.4, 115.5,
1
13
6
+
114.8, 106.6, 100.0, 95.0, 66.7, 61.1, 56.9, 56.4, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for C24
H
25
N
2
7
O ,
453.1656; found, 453.1653.
(8-cyano-7-(methoxymethoxy)-4-(4-(N-methylformamido)phenyl)quinolin-2-yl)methyl acetate (11u); HRMS
+
(ESI-QTOF) m/z: [M + H] calcd for C23
was carried directly to the next step.
H
22
N
3
O , 420.1554; found, 420.1555. Not isolated. The solid obtained
5
(
4
8-cyano-7-(methoxymethoxy)-4-(3-(N-methylformamido)phenyl)quinolin-2-yl)methyl acetate (11v). (4 mg,
3% yield). H NMR (500 MHz, chloroform-d, δ): 8.62 (s, 1H), 8.00 (d, J = 9.5 Hz, 1H), 7.64 – 7.59 (m, 1H),
1
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2
2
2
2
2
2
2
3
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7
.55 – 7.50 (m, 1H), 7.38 – 7.35 (m, 2H), 7.28 (d, J = 2.2 Hz, 2H), 5.52 (s, 2H), 5.47 (s, 2H), 3.60 (d, J = 1.8
13
Hz, 3H), 3.41 (s, 3H), 2.28 (s, 3H); C NMR{1H} (126 MHz, chloroform-d, δ): 170.8, 162.1, 162.0, 158.8,
148.9, 148.5, 142.8, 138.7, 131.4, 130.2, 127.2, 122.8, 122.4, 121.0, 118.6, 115.8, 114.5, 100.3, 95.0, 66.7, 56.9,
+
32.1, 21.0; HRMS (ESI-QTOF) m/z: [M + H] calcd for C23
H
22
N
3
5
O , 420.1554; found, 420.1551.
General procedure for the preparation of acetates 12a-v
To a solution of one of the acetates 11a-v (0.05 mmol, 1 eq) in CH
dropwise. The reaction was stirred for up to 5 h until HPLC showed complete consumption of the starting
material, then concentrated to dryness. The product was purified either by trituration with tetrahydrofuran or by
reverse-phase preparative chromatography (water/CH
2
2
Cl (2 mL), TFA (0.2 mL) was added
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
3
CN), affording the respective protected acetate 12a-v.
1
(4-chloro-8-cyano-7-(hydroxy)quinolin-2-yl)methyl acetate (12a). (12 mg, 90% yield). H NMR (500 MHz,
methanol-d , d): 9.07 (d, J = 9.3 Hz, 1H), 8.39 (s, 1H), 8.24 (d, J = 9.4 Hz, 1H), 6.11 (s, 2H), 3.96 (p, J = 1.7
Hz, 3H); C NMR{1H} (126 MHz, methanol-d , d): 171.4, 160.2, 150.4, 143.8, 130.7, 120.8, 119.8, 118.6,
4
1
3
4
+
1
2
15.9, 95.8, 66.7, 30.2, 21.3; HRMS (ESI-QTOF) m/z: [M + H] calcd for C13
77.0380.
H10ClN
2
3
O , 277.0374; found,
1
(4,8-dicyano-7-(hydroxy)quinolin-2-yl)methyl acetate (12b). (3 mg, 45% yield). H NMR (500 MHz, methanol-
d
3
1
2
4
, d): 8.28 – 8.21 (m, 1H), 7.90 – 7.85 (m, 1H), 7.52 – 7.45 (m, 1H), 5.48 – 5.42 (m, 2H), 2.26 (t, J = 3.9 Hz,
1
3
H); C NMR{1H} (126 MHz, methanol-d , d): 171.0, 165.2, 159.0, 148.6, 130.2, 121.1, 120.4, 119.5, 119.0,
14.6, 113.8, 95.6, 65.6, 19.3; HRMS (ESI-QTOF) m/z: [M + H] calcd for C14
68.0715.
4
+
H
10
N
3
O
3
, 268.0717; found,
1
(8-cyano-4-(dimethylamino)-7-(hydroxy)quinolin-2-yl)methyl acetate (12c). (21 mg, 99% yield). H NMR (500
MHz, methanol-d
4
, d): 8.46 (d, J = 9.6 Hz, 1H), 7.24 (d, J = 9.5 Hz, 1H), 7.00 (s, 1H), 5.37 (s, 2H), 3.54 (s, 6H),
1
3
2
1
2
.22 (s, 3H); C NMR{1H} (126 MHz, methanol-d , d): 170.4, 166.5, 160.1, 149.4, 142.5, 133.8, 114.7, 111.9,
10.6, 102.3, 87.8, 61.7, 43.7, 19.1; HRMS (ESI-QTOF) m/z: [M + H] calcd for C15
86.1205.
4
+
H
16
N
3
3
O , 286.1186; found,
1
(8-cyano-7-(hydroxy)-4-morpholinoquinolin-2-yl)methyl acetate (12d). (14 mg, 99% yield). H NMR (500
MHz, acetonitrile-d3, δ): 8.10 (d, J = 9.4 Hz, 1H), 7.35 (d, J = 9.5 Hz, 1H), 6.97 (s, 1H), 5.29 (s, 2H), 3.91 – 3.86
13
(
1
m, 4H), 3.67 (t, J = 4.7 Hz, 4H), 2.20 (s, 3H); C NMR{1H} (126 MHz, acetonitrile-d3, δ): 170.7, 166.7, 160.1,
52.4, 144.6, 132.2, 116.7, 113.4, 112.5, 104.9, 89.9, 66.1, 63.1, 52.6, 20.0; HRMS (ESI-QTOF) m/z: [M + H]+
calcd for C17
H
18
N
3
4
O , 328.1292; found, 328.1293.
1
(
8-cyano-7-(hydroxy)-4-(phenylethynyl)quinolin-2-yl)methyl acetate (12e). (5 mg, 81% yield). H NMR (500
MHz, methanol-d , d): 8.40 (dd, J = 9.2, 2.1 Hz, 1H), 7.71 (dt, J = 7.9, 2.0 Hz, 2H), 7.57 (d, J = 2.1 Hz, 1H),
7.49 (h, J = 5.2, 4.8 Hz, 3H), 7.35 (dd, J = 9.2, 2.2 Hz, 1H), 5.40 (d, J = 2.2 Hz, 2H), 2.26 (d, J = 2.0 Hz, 3H);
4
1
3
C NMR{1H} (126 MHz, methanol-d
120.6, 119.5, 118.4, 114.5, 99.1, 95.0, 83.6, 66.0, 19.4; HRMS (ESI-QTOF) m/z: [M + H] calcd for
, 343.1077; found, 343.1058.
4
, d): 171.1, 164.4, 158.5, 148.6, 131.7, 131.5, 130.8, 129.6, 128.5, 121.6,
+
C
21
H
15
N
2
O
3
1
(8-cyano-7-(hydroxy)-4-methylquinolin-2-yl)methyl acetate (12f). (18 mg, 99% yield). H NMR (500 MHz,
methanol-d , d): 8.18 (d, J = 9.2 Hz, 1H), 7.31 (s, 1H), 7.26 (d, J = 9.3 Hz, 1H), 5.36 (s, 2H), 2.71 (s, 3H), 2.24
(s, 3H); C NMR{1H} (126 MHz, methanol-d , d): 171.1, 163.9, 158.2, 148.0, 147.2, 130.2, 121.3, 118.2,
117.3, 114.7, 94.5, 65.9, 19.4, 17.3; HRMS (ESI-QTOF) m/z: [M + H] calcd for C14
257.0919.
4
1
3
4
+
H
13
N
2
3
O , 257.0921; found,
(
8-cyano-7-hydroxy-4-(1H-pyrrol-3-yl)quinolin-2-yl)methyl acetate (12g). To a solution of 11g (10 mg, 0.02
mmol, 1 eq) in THF (2 mL) at 0 °C, a 1 M solution of tetrabutylammonium fluoride (0.022 mL, 0.022 mmol,
.1 eq) in THF was added dropwise. The mixture was stirred at 0 °C for 30 min, then at room temperature for 1
1
h. When the reaction was complete, as indicated by LC-MS analysis, the solvent was evaporated. The resulting
residue was subjected to the procedure described for converting 11a into the MOM ether 12a, affording 12g (4
mg, 65% yield). H NMR (500 MHz, acetonitrile-d3, δ): 9.73 (s, 1H), 8.50 (d, J = 9.3 Hz, 1H), 7.42 (s, 1H), 7.33
1
(d, J = 9.3 Hz, 1H), 7.24 (dt, J = 3.2, 1.8 Hz, 1H), 6.99 (q, J = 2.5 Hz, 1H), 6.55 (td, J = 2.7, 1.6 Hz, 1H), 5.34
1
3
(s, 2H), 2.20 (s, 3H); C NMR{1H} (126 MHz, acetonitrile-d3, δ): 170.6, 163.2, 158.2, 149.5, 145.1, 132.6,
+
119.9, 119.5, 119.3, 116.8, 115.4, 109.1, 95.2, 66.4, 52.5, 25.1, 20.1; HRMS (ESI-QTOF) m/z: [M + H] calcd
for C17
H
14
N
3
O
3
, 308.1030; found, 308.1024.
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(
8-cyano-7-hydroxy-4-phenylquinolin-2-yl)methyl acetate (12h). (12 mg, 93% yield). H NMR (500 MHz,
DMSO-d , d): 12.06 (s, 1H), 7.95 (d, J = 9.3 Hz, 1H), 7.64 – 7.51 (m, 5H), 7.39 (s, 1H), 7.35 (d, J = 9.3 Hz,
, d): 170.8, 164.4, 158.5, 149.6, 149.3,
37.2, 132.2, 129.9, 129.4, 129.3, 119.6, 119.1, 118.3, 115.9, 95.0, 66.5, 21.2; HRMS (ESI-QTOF) m/z: [M +
6
13
1
1
H), 5.38 (s, 2H), 2.19 (s, 3H); C NMR{1H} (126 MHz, DMSO-d
6
+
H] calcd for C19
H
15
N
2
3
O , 319.1077; found, 319.1083.
1
(8-cyano-7-(hydroxy)-4-(p-tolyl)quinolin-2-yl)methyl acetate (12i). (10 mg, 99% yield). H NMR (500 MHz,
methanol-d , d): 7.99 (d, J = 9.3 Hz, 1H), 7.38 (s, 4H), 7.34 (s, 1H), 7.21 (d, J = 9.3 Hz, 1H), 5.42 (s, 2H), 2.46
s, 3H), 2.23 (s, 3H); C NMR{1H} (126 MHz, methanol-d
134.1, 131.9, 129.1, 129.1, 119.8, 117.6, 117.5, 114.8, 94.7, 66.1, 19.9, 19.4; HRMS (ESI-QTOF) m/z: [M + H]
calcd for C20 , 333.1234; found, 333.1250.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
4
1
3
(
4
, d): 171.2, 164.0, 158.1, 150.3, 149.0, 138.9,
+
H
17
N
2
O
3
1
(8-cyano-7-(hydroxy)-4-(4-methoxyphenyl)quinolin-2-yl)methyl acetate (12j). (9 mg, 95% yield). H NMR
(500 MHz, methanol-d , d): 8.04 (d, J = 9.3 Hz, 1H), 7.49 – 7.42 (m, 2H), 7.35 (s, 1H), 7.22 (d, J = 9.3 Hz, 1H),
7.16 – 7.10 (m, 2H), 5.43 (s, 2H), 3.91 (s, 3H), 2.23 (s, 3H); C NMR{1H} (126 MHz, methanol-d
164.0, 160.6, 158.1, 150.2, 149.1, 131.9, 130.5, 129.2, 119.9, 117.6, 117.5, 114.8, 114.0, 94.7, 66.1, 54.5, 19.4;
4
1
3
4
, d): 171.2,
+
HRMS (ESI-QTOF) m/z: [M + H] calcd for C20
H
17
N
2
O
4
, 349.1183; found, 349.1176.
1
(
8-cyano-4-(4-cyanophenyl)-7-(hydroxy)quinolin-2-yl)methyl acetate (12k). (6 mg, 99% yield). H NMR (500
MHz, methanol-d , d): 7.99 – 7.93 (m, 2H), 7.90 (d, J = 9.3 Hz, 1H), 7.76 – 7.70 (m, 2H), 7.42 (s, 1H), 7.27 (d,
4
1
3
J = 9.3 Hz, 1H), 5.46 (s, 2H), 2.24 (s, 3H); C NMR{1H} (126 MHz, methanol-d
1
HRMS (ESI-QTOF) m/z: [M + H] calcd for C20
4
, d): 171.2, 164.1, 158.4,
49.2, 148.0, 141.9, 132.4, 131.1, 130.3, 130.2, 119.1, 118.2, 117.9, 117.5, 114.6, 112.5, 95.2, 70.1, 66.1, 19.4;
+
H
14
N
3
O
3
, 344.1030; found, 344.1034.
1
4
-(2-(acetoxymethyl)-8-cyano-7-hydroxyquinolin-4-yl)benzoic acid (12l). (5 mg, 99% yield). H NMR (500
MHz, methanol-d , d): 8.27 – 8.21 (m, 2H), 7.95 (d, J = 9.3 Hz, 1H), 7.68 – 7.59 (m, 2H), 7.42 (s, 1H), 7.26 (d,
4
1
3
J = 9.3 Hz, 1H), 5.46 (s, 2H), 2.24 (s, 3H); C NMR{1H} (126 MHz, methanol-d
1
QTOF) m/z: [M + H] calcd for C20
4
, d): 171.2, 167.8, 164.1,
58.4, 149.2, 149.0, 141.7, 131.4, 131.1, 129.8, 129.4, 119.4, 118.0, 117.5, 114.7, 95.1, 66.1, 19.4; HRMS (ESI-
+
H
15
N
2
5
O , 363.0975; found, 363.0976.
1
(
(
7
1
1
8-cyano-4-(4-fluorophenyl)-7-(hydroxy)quinolin-2-yl)methyl acetate (12m). (18 mg, 94% yield). H NMR
500 MHz, methanol-d , d): 7.96 (d, J = 9.3 Hz, 1H), 7.59 – 7.53 (m, 2H), 7.37 (s, 1H), 7.36 – 7.30 (m, 2H),
.24 (d, J = 9.3 Hz, 1H), 5.44 (s, 2H), 2.24 (s, 3H); C NMR{1H} (126 MHz, methanol-d
63.2 ( JC–F = 248.0 Hz), 158.3, 149.2, 149.0, 137.3, 133.3, 131.5, 131.2 ( JC–F = 8.2 Hz), 119.7, 117.8, 117.7,
15.3 ( JC–F = 22.1 Hz), 95.0, 66.2, 19.4; HRMS (ESI-QTOF) m/z: [M + H] calcd for C19
4
1
3
4
, d): 171.21, 163.97,
1
3
2
+
H14FN
2
O
3
, 337.0983;
found, 337.0970.
1
(
8-cyano-4-(4-(dimethylamino)phenyl)-7-(hydroxy)quinolin-2-yl)methyl acetate (12n). (7 mg, 99% yield). H
NMR (500 MHz, methanol-d , d): 8.06 (d, J = 9.4 Hz, 1H), 7.56 – 7.48 (m, 2H), 7.36 (s, 1H), 7.27 – 7.19 (m,
4
1
3
3
1
H), 5.42 (s, 2H), 3.18 (s, 6H), 2.24 (s, 3H); C NMR{1H} (126 MHz, methanol-d
4
, d): 171.2, 164.0, 158.0,
49.9, 149.2, 148.6, 132.8, 131.9, 130.6, 119.7, 117.5, 117.3, 114.9, 94.7, 66.1, 53.4, 41.3, 19.4; HRMS (ESI-
+
QTOF) m/z: [M + H] calcd for C21
H
20
N
3
O
3
, 362.1499; found, 362.1479.
1
(
8-cyano-7-(hydroxy)-4-(m-tolyl)quinolin-2-yl)methyl acetate (12o). (14 mg, 99% yield). H NMR (500 MHz,
methanol-d , d): 7.95 (d, J = 9.3 Hz, 1H), 7.43 (t, J = 7.6 Hz, 1H), 7.37 – 7.29 (m, 3H), 7.26 (dt, J = 7.4, 1.5 Hz,
H), 7.19 (d, J = 9.3 Hz, 1H), 5.41 (s, 2H), 2.45 (s, 3H), 2.22 (s, 3H); C NMR{1H} (126 MHz, methanol-d
d): 171.2, 164.0, 158.1, 150.4, 149.0, 138.5, 137.0, 131.9, 129.7, 129.3, 128.4, 126.3, 119.8, 117.6, 117.5,
4
13
1
4
,
+
1
3
14.8, 94.7, 66.1, 20.0, 19.4; HRMS (ESI-QTOF) m/z: [M + H] calcd for C20
H
17
N
2
O
3
, 333.1234; found,
33.1259.
1
(
(
8-cyano-7-(hydroxy)-4-(3-methoxyphenyl)quinolin-2-yl)methyl acetate (12p). (18 mg, 99% yield). H NMR
500 MHz, methanol-d , d): 7.96 (d, J = 9.3 Hz, 1H), 7.46 (t, J = 8.1 Hz, 1H), 7.34 (s, 1H), 7.20 (d, J = 9.3 Hz,
4
1
3
1H), 7.11 – 7.07 (m, 1H), 7.05 – 7.00 (m, 2H), 5.41 (s, 2H), 3.87 (s, 3H), 2.22 (s, 3H); C NMR{1H} (126
MHz, methanol-d , d): 171.2, 164.0 160.0, 158.1, 150.0, 149.0, 138.4, 131.8, 129.6, 121.4, 121.3, 119.7, 117.7,
4
+
117.5, 114.8, 114.0, 94.8, 66.1, 54.5, 19.4; HRMS (ESI-QTOF) m/z: [M + H] calcd for C20
H
17
N
2
O
4
, 349.1183;
found, 349.1181.
1
(8-cyano-4-(3-fluorophenyl)-7-(hydroxy)quinolin-2-yl)methyl acetate (12q). (27 mg, 99% yield). H NMR (500
MHz, DMSO-d , d): 12.11 (s, 1H), 7.94 (dd, J = 9.3, 2.4 Hz, 1H), 7.64 (tdt, J = 11.1, 7.7, 3.8 Hz, 1H), 7.47 –
6
29
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