Novel Quinazolinone Inhibitors of ALK2 Flip between Alternate Binding Modes: Structure-Activity Relationship, Structural Characterization, Kinase Profiling, and Cellular Proof of Concept

Article abstract of DOI:10.1021/acs.jmedchem.8b00782

Structure-activity relationship and crystallographic data revealed that quinazolinone-containing fragments flip between two distinct modes of binding to activin receptor-like kinase-2 (ALK2). We explored both binding modes to discover potent inhibitors and characterized the chemical modifications that triggered the flip in binding mode. We report kinase selectivity and demonstrate that compounds of this series modulate ALK2 in cancer cells. These inhibitors are attractive starting points for the discovery of more advanced ALK2 inhibitors.

Full text of DOI:10.1021/acs.jmedchem.8b00782

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pubs.acs.org/jmc
Cite This: J. Med. Chem. XXXX, XXX, XXX−XXX
Novel Quinazolinone Inhibitors of ALK2 Flip between Alternate
Binding Modes: Structure−Activity Relationship, Structural
Characterization, Kinase Profiling, and Cellular Proof of Concept
§
§
†
Liam Hudson, James Mui, Santiago Vazquez, Diana M. Carvalho,§ Eleanor Williams,‡ Chris Jones,§
́
Alex N. Bullock,‡ and Swen Hoelder*,§
§Institute of Cancer Research, 15 Cotswold Road, Sutton, Surrey SM2 5NG, United Kingdom
‡Structural Genomics Consortium, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ,
United Kingdom
†
̀
̀
̀
́
Laboratori de Química Farmaceutica (Unitat Associada al CSIC), Facultat de Farmacia i Ciencies de l’Alimentacio, and Institute of
Biomedicine (IBUB), Universitat de Barcelona, Av. Joan XXIII s/n, Barcelona E-08028, Spain
S
* Supporting Information
ABSTRACT: Structure−activity relationship and crystallo-
graphic data revealed that quinazolinone-containing fragments
flip between two distinct modes of binding to activin receptor-
like kinase-2 (ALK2). We explored both binding modes to
discover potent inhibitors and characterized the chemical
modifications that triggered the flip in binding mode. We
report kinase selectivity and demonstrate that compounds of
this series modulate ALK2 in cancer cells. These inhibitors are
attractive starting points for the discovery of more advanced
ALK2 inhibitors.
ALK2 inhibitors have been reported and fall into two series
(Figure 1). The first contains a pyrazolo[1,5-a]pyrimidine core
and derives from dorsomorphin. Dorsomorphin was initially
reported as an adenosine monophosphate (AMP)-activated
INTRODUCTION
■
ALK2 (gene: ACVR1) is a serine/threonine kinase in the bone
morphogenetic protein (BMP) pathway and one of seven
(ALK1−7) type-I receptors in the BMP and transforming
growth factor beta (TGFβ) signaling pathways.1
Signaling through ALK2 is deregulated in two disease
contexts. The first is fibrodysplasia ossificans progressiva
(FOP), an extremely rare condition of ectopic bone formation
resulting in a progressive loss of mobility.2 Heterozygous
missense mutations in ACVR1 (most commonly R206H) lead
to neofunction in response to activin A as well as increased
BMP signaling through SMAD1/5/8the driving force in
FOP.3 The second disease is diffuse intrinsic pontine glioma
(DIPG), a highly infiltrative tumor originating in the pons of
the brainstem.4 DIPGs arise with a peak age of incidence of 6−
7 years and have a fatality of 100%; median survival is 9−12
months.4 As DIPGs grow diffusely throughout the vital midline
brain region, surgical resection is generally considered
impossible, and the current treatment of radiotherapy, while
providing short-term relief of symptoms, does not prevent
rapid disease progression.5
ACVR1 mutations are observed in 24% of DIPG patients.4
These mutations occur in the cytoplasmic domains of ALK2
and modulate kinase activity though (i) destabilizing the
inactive conformation of the kinase and (ii) disrupting the
binding of a negative regulator protein, FKBP12.2 The high
frequency of ALK2 mutations in DIPG strongly suggests a
contribution to disease phenotype.
Figure 1. A selection of ALK2 and ALK5 inhibitors (the atom marked
in red is the main anchor point to the kinase hinge residues).
Received: May 16, 2018
© XXXX American Chemical Society
A
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a
protein kinase inhibitor, but was found in a zebrafish embryo
dorsalization assay to selectively inhibit BMP signaling through
SMAD1/5/8.6 Further development led to LDN-193189,7
LDN-212854,8 and ML347,9 which had improved microsomal
stability, potency, and selectivity. In addition, these molecules
demonstrated efficacy in mouse models of FOP.8 However,
these compounds have a number of kinase off-targets and
display dose-limiting toxicity with a 10% loss in body weight in
animal models.10 A second series of inhibitor based on a
pyridine core (e.g., K0228811 and LDN-21411712), with
equivalent biochemical potency and improved kinome
selectivity, has also been reported (Figure 1).
Table 1. SAR at Quinazolinone 6-Position
RESULTS
■
We identified 6-pyrazole quinazolinone, 1, as a ligand efficient
inhibitor of ALK2 (IC50 = 8.2 μM; LE = 0.45) through cross-
screening of a focused kinase fragment library, using
Invitrogen’s LanthaScreen binding assay. 1 shares features
with reported ALK5 inhibitors such as PF-0367114813 and
compound 19.14 These are known to bind to the hinge of
ALK5 through a single polar contact at the N-1 position of the
quinazolinone moiety, with the 2-methylpyridine directing
toward the ALK5 Ser280 gatekeeper residue, forming a key
water mediated hydrogen bond to Lys232 (Figure 2).14
Figure 2. (A) Docking pose of 4 in ALK2 (structure used: 3Q4U).
(B) X-ray structure of analogous naphthyridine-based inhibitor
(compound 19) of ALK514 (PDB 1VJY).
Interestingly, PF-03671148 has been shown to be selective
against ALK1 likely due a larger gate keeper (Thr) causing a
clash with the pyridine substituent.13 Given that ALK2 also
features a threonine gatekeeper residue (Thr283), it is also
unlikely to be potently inhibited by PF-03671148.
Unfortunately, attempts to solve the structure of 1 bound to
ALK2 were not successful. However, since 1 did not feature
the pyridine substituent of the published ALK5 inhibitor
(compound 19), we initially hypothesized that it explored a
similar binding mode when binding to ALK5 (Figure 2).
We sought to investigate whether quinazolinone 1 could be
optimized into an independent series of ALK2 inhibitor and
characterize its binding mode.
a
IC50 data is an average of 2−4 measurements by LanthaScreen Eu
kinase binding assay.
the pyrazole for a bicycle (7−9). Since DIPG requires brain
penetrable drugs, this had the added benefit of reducing the
TPSA, a well-established predictor for passive permeability
across the blood−brain barrier.15 Gratifyingly, this afforded a
40−80-fold improvement in potency over the initial hit. As the
4- and 5-quinoline examples (7 and 8) represented the most
promising compounds so far, with sub-μM potency, good
ligand efficiency and low TPSA, we decided to focus further
modification on these isomers.
We started our investigations at the quinazolinone 6-
position, by modifying the pyrazole moiety (Table 1). N-
Methylation of pyrazole (2) had a minor negative effect on
ALK2 binding affinity, whereas substitution at the pyrazole 3-
position was tolerated. Interestingly, increasing the size from
methyl to cyclopropyl (4) was not only tolerated but led to a
21-fold potency increase. A 3,5-dimethylpyrazole (6) main-
tained sub-μM potency and was the most efficiently binding
pyrazole derivative with an impressive LE of 0.51. This initial
set of compounds, particularly compounds 2 and 6, suggested
that the pyrazole was not the hinge binding motif and instead
binds to Lys235 through a water bridge, as observed for
compound 19 in Figures 1 and 2. This prompted us to replace
On the basis of the observed structure−activity relationship
(SAR), we hypothesized that the compounds presented in
Table 1 adopted a binding mode in which the variable
heteroaromatic group occupied the ALK2 central pocket,
extending toward the catalytic lysine (Lys235), similarly to
reported ALK5 inhibitors (Figure 2).14 We also expected that
this binding mode would be preserved between the pyrazoles
and quinolines, which are present in several reported ALK2
inhibitors (Figure 1). However, it was still not clear how the
quinazolinone core interacted with the hinge region. In an
effort to shed light on this question, we positioned a methyl
group at various positions around the quinazolinone ring
(Table 2).
B
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a
a
Table 2. Quinazolinone Methyl Scan SAR
Table 3. SAR at Quinazolinone 3-Position
a
IC50 data is an average of 2−4 measurements by LanthaScreen Eu
kinase binding assay.
a
The 30-fold gain in potency achieved through the addition of
morpholine (16) to phenyl-only compound 17 suggests that
the phenyl ring is acting as a linker for this polar function.
However, a simple propyl linker (19) to the morpholine unit
does not afford a similar potency boost. In addition,
maintaining the phenyl ring, but removing the ether
functionality [of 16], leaving a dimethyl aniline (20) had a
negligible effect on bindingstrongly suggesting that the
amine, and its precise position, are key to achieving potent
inhibitors of ALK2.
IC50 data is an average of 2−4 measurements by LanthaScreen Eu
kinase binding assay.
When compared to the desmethyl analogues (7 and 8), a 5-
methyl group (10 and 11) did not alter potency. This was
consistent with the binding mode suggested in Figure 2, where
the additional methyl group would direct toward solvent. 3-
Methyl isomers 12 and 13 were also of equivalent potency,
which again was consistent with a binding mode as in Figure 2
where the 3-methyl directs toward the solvent channel of
ALK2. Surprisingly, analogous 2-methyl isomers (14 and 15)
also displayed equal potency at ALK2. This was an unexpected
result given that a 2-position substituent should clash with
protein under the proposed binding model.
While this surprising tolerance to substitution at all three
positions (Table 2) did not clearly suggest a preferred hinge
binding motif, the 3-methyl isomer 12 stood out due to the
low TPSA and closest analogy to published inhibitors.7
We decided to explore further substitution at the
quinazolinone 3-position and incorporated solvent channel
groups that had led to activity gains in other series, e.g., the
pyrazolo[1,5-a]pyrimidine series. Introduction of a 4-morpho-
linophenyl group (16) was found to increase the potency 5-
fold (Table 3) and yielded the most potent compound up to
this point. However, the additional 12 heavy atoms from the 4-
morpholinophenyl group did inflict a 0.11−0.19 LE unit
penalty, suggesting that the solvent channel group was
suboptimal.
With more potent compounds in hand, we reattempted
cocrystallization and indeed managed to obtain the cocrystal
structure of 16 with ALK2 to 2.2 Å resolution (Figure 3). The
compound indeed displayed a binding mode similar to the
reported inhibitor LDN-193189quinazolinone N-1 interacts
as an HBA for the ALK2 hinge residue His286, the 4-
morpholino phenyl group directs through the solvent channel,
and the 4-quinoline occupies the central pocket, with the
quinoline-N-atom forming a water-bridged interaction to
Lys235. Other similarities between the solved structure of 16
and LDN-193189 include the variable position of morpholine
and methylpiperidine in the solvent channelmultiple
conformations exist for both compounds in their respective
asymmetric units suggesting that while the phenyl-bonded N
atoms may have a significant role in binding the distal N-Me/
O atom is unlikely to contribute heavily. We can only speculate
on the reason why the morpholine amine contributes so
strongly to binding. It is unlikely that this amine is charged due
to the aniline character and electron withdrawing ether
function. However, upon inspection of the electron density
map for 16 a water bridged hydrogen bond to V214 is visible
in one ALK2 chain in the asymmetric unit and may contribute
to the gain in potency (Figure 3A). A notable difference versus
available structures of pyrazolo[1,5-a]pyrimidine-based ALK2
inhibitors (PDB 3Q4U) is that the central pocket quinoline
penetrates deeper toward Lys235 (Figure 3B), by virtue of the
larger hinge-binding core.
To understand why only modest potency gains were
afforded a series of truncated and modified analogues were
prepared: phenyl (17), cyclohexyl (18), 3-morpholinopropyl
(19), and 4-dimethyl aniline (20). Comparison of these
analogues showed that the phenyl ring alone leads to a loss of
activity compared to the methyl derivative, 12. Replacement by
a cyclohexyl group did not drastically reduce binding further,
suggesting that saturated or otherwise three-dimensional
groups may be tolerated in this region of the ALK2 pocket.
C
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Figure 3. (A) Cocrystal structure of 16 in ALK2 showing three H-
bond acceptors for H286, K235, and V214 (PDB 6GIN). (B) Overlay
of 16 (brown) with LDN-193189 (green, PDB 3Q4U) showing
deeper penetrance of 4-quinoline toward K235 for 16, and slight
change in position of the solvent channel group.
The binding mode revealed by the crystal structure was
consistent with our earlier hypothesis of preferred binding
mode (cf. Figure 2 with the key hinge binding interaction
between the quinazolinone N-1 and His286). An interesting
observation was that some compounds (e.g., 14 and 15)
maintained potency even though the additional 2-methylation
would likely cause a clash with the hinge residues of ALK2
suggesting that they bind through an alternate binding mode.
We therefore sought to solve additional structures and were
able to obtain the structure of compound 11. Interestingly, 11
displayed a flipped binding mode (Figure 4A) in which the
quinazolinone core bound to His286 through the amide, as a
donor and acceptor. This also altered the vector from the
quinazolinone 6-position such that the quinoline also flipped in
order to fill the same volume in the ALK2 central pocket as for
16 (Figure 4B).
Figure 4. (A) Cocrystal structure of 11 with ALK2 (PDB 6GI6). (B)
Superposition of costructures of 11 (blue) and 16 (brown). (C)
Superposition of the costructures of 11 (blue) and 21 (orange, PDB
6GIP).
a
Table 4. SAR of Flipped Binding Series
Inspection of the compound bound in the flipped binding
mode (11) suggested that introduction of small hydrophobic
groups in the 2-position should not only be tolerated but
would lead to additional hydrophobic interaction (Table 4).
Interestingly, while introduction of the 2- and 5-methyl groups
individually (Table 2) was tolerated but did not lead to an
increase in activity, introduction of both (21) afforded a 6-fold
increase in potency (Table 4). We hypothesized that this
cooperative increase in potency can be explained by the change
in binding mode: 2-methylation forces adoption of the flipped,
and presumably lower preference binding mode [for
unsubstituted quinazolinones] (Figure 4C); however, there is
no change in potency due to the addition of a methyl group in
a relatively nonpolar part of the binding pocket. 5-Methylation
a
IC50 data is an average of 2−4 measurements by LanthaScreen Eu
Kinase Binding Assay.
fills the excluded volume created by flipping binding mode,
which in the absence of 2-methylation is apparently enough to
D
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compensate for adopting the less energetically favored flipped
binding mode. Once the flipped mode is induced by one
methyl substituent, addition of the second does not incur a
further penalty and reaps the benefit of the newly formed
interaction.
To assess the available space at the quinazolinone 2-position
of the inhibitors binding in the flipped binding mode, we
designed and prepared a few additional compounds.
Crystallography suggested that the 2-methyl group could be
replaced by larger groups. This was indeed the case. Increasing
the size of the 2-substitutent to ethyl (22) or benzyl (23) was
tolerated but did lead to a modest reduction in potency
mirroring the phenyl-only compound for the precedented
binding mode (13), suggesting that there is scope to further
investigate substituents at this position.
Furthermore, as the flipped binders do not appear to make
use of N-1 for interaction with ALK2, we hypothesized that
replacement with a C atom would result in additional
hydrophobic interaction and loss of the desolvation penalty
upon binding due to the polar heteroatom. The resulting
isoquinolinone 24 indeed displayed 10 nM potency with a
superb LE of 0.49.
At this stage, two divergent series with quinazolinone cores
were developed to the stage of a having potency < 50 nM. We
hypothesized that inhibitors of the normal and flipped modes
would display distinct selectivity profiles. To test this
hypothesis, the most potent normal and flipped binding
quinazolinones (16 and 21 respectively) were assessed in
DiscoveRx’s scanEDGE panel of 97 diverse kinases, plus all
reported off-targets of the pyrazolo[1,5-a]pyrimidine and
pyridine series (Table S1).8,9,12
Both quinazolinone based inhibitors displayed excellent
selectivity in the kinome panel tested, though some notable
differences were evident (Figure 5). At 1 μM the normal
binder, 16, showed similarly potent inhibition of ALK6,
platelet-derived growth factor receptor (PDGFR) A and B and
Proto-Oncogene receptor tyrosine kinase KIT. While the
flipped binder, 21, showed selectivity confined to the tyrosine
kinase-like (TKL) family of kinasesa surprising result given
its low molecular weight. Aside from the highly homologous
ALKs 1, 4, 5, and 6, RAF1 and BRAF were also inhibited by
21. These results indicate that the two different compounds
have distinct inhibition profiles within the kinome, versus each
other as well as reported inhibitors and that both have a highly
encouraging level of selectivity against the panel of kinases
screened.
KD values were obtained for ALKs 1−6 and all off-targets
identified in Figure 5, for both 16 and 21 (Table 5) using
DiscoverX’s KdELECT assay. 16 had similar affinity for ALKs
1, 2, 3, and 6 (which all signal through SMADs 1, 5, and 8)
with moderate selectivity over ALKs 4 and 5 (which signal
through SMADs 2 and 3). This profile is similar to reported
ALK2 inhibitors.8,9,12 The smaller, flipped binder, 21,
displayed an atypical profilewith lower selectivity over
ALKs 4 and 5 and considerable variance in affinity for ALKs
1, 2, 3, and 6. The fact that 21 binds ALKs 1 and 6 16-fold
more potently than ALK2 shows that 21 is not yet favorable
for FOP and DIPG which harbor various activating mutations
in ALK2. However, this is the first case, to our knowledge, of a
small molecule with ALK1 selectivity over ALK2, which shares
79% sequence identity in their kinase domains.11 This is a
potentially useful property if developed further to investigate
Figure 5. Kinase selectivity profile of 16 and 21 at 1 μM. Blue circle −
ALK2; Green circles ≤ 65% probe displacement; small red circle =
65−90% probe displacement; intermediate circle = 90−95% probe
displacement; larger red circle = 95−99% probe displacement.
Table 5. KD’s for ALKs 1−6 and All off-Targets Identified
a
for Compounds 16 and 21
KD (nM)
kinase
ALK1
16
420
21
41
ALK2
ALK3
ALK4
ALK5
ALK6
BRAF
RAF1
330
610
11000
19000
96
640
2700
690
1000
39
65
330
KIT
54
PDGRFA
PDGRFB
43
250
a
KD’s calculated from duplicate 11-point dose−response curves;
KdELECT, DiscoverX
E
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a
the role of ALK1 in various disease contexts, particularly in
regulating angiogenesis.16
Scheme 3. Synthesis of Isoquinolinones
Finally, to achieve proof of concept that this class of
compound shows activity in cells, we tested if 24 modulates
the BMP pathway downstream of ALK2 (Figure 6) in HSJD-
a
Figure 6. Dose-dependent reduction in markers of ALK2 inhibition in
(a) Piperidine, 110 °C, 64%; (b) (i) NEt3, acetone, ethyl
chloroformate, 0 °C − RT; (ii) NaN3, water, RT, 97%; (c) I2, 1,2-
dichlorobenzene, 140−180 °C, 50% [3:2] 29:30; (d) PdCl2(PPh3)2,
Na2CO3(aq), 1,4-dioxane, 150 °C, 61%.
HSJD-DIPG7 cells.
DIPG-007 patient derived cells (H3F3A K27M and ACVR1
R206H) at three different concentrations (0.1 μM, 1 μM, and
10 μM). Encouragingly, 24 displayed a dose-dependent
reduction of pSMAD1/5/8 and ID1.
Compounds were prepared principally by a multicomponent
reaction between orthoesters, amines, and anthranillic acids,
followed by a Suzuki coupling (Scheme 1). For non-
chromatographic separation, the major product (29) was
functionalized by a Suzuki coupling.
DISCUSSION AND CONCLUSIONS
■
In conclusion, we identified a ligand efficient quinazolinone
fragment (1) for inhibition of the ALK2 kinase domain
through systematic cross screening. We found that the 6-
pyrazole of 1 could be modified or replaced with bicyclic
groups for gains in potency and that the activity was
surprisingly tolerant to addition of methyl groups at the
quinazolinone 2-, 3-, and 5-positions. Guided by crystallog-
raphy, we were able to rationalize this tolerance through a
flipped binding mode. We explored both binding modes to
discover potent inhibitors. Our work shows that there is scope
for further investigation of the SAR of both series and that the
kinome selectivity profiles for example compounds (16 and
21) are not only distinct from one another but also do not hit
off-targets for previously reported ALK2 inhibitors at the
concentration tested. Finally we demonstrated that compound
24 modulates ALK2 in cells in a dose-dependent manner.
The compounds presented here thus represent attractive
starting points to discover potent and selective inhibitors of
activin receptor-like kinases.
a
Scheme 1. General Route to Quinazolinone Derivatives
a
(a) 110 °C, 16−100%; (b) PdCl2(PPh3)2, NaOH(aq), 1,4-dioxane,
120−150 °C, 12−100%.
commercially available pyrazole boronic acids/esters, the
parent pyrazole was brominated, then tosyl-protected (ix−x),
which allowed for a one-pot borylation and Suzuki protocol.
2-Benzyl quinazolinones were prepared by treatment of
benzylcyanide with hydroxylamine, forming an intermediate
amidoxime (Scheme 2).17 In the same pot, reaction with
anthranillic acid, 25, afforded 6-bromo intermediate 26, which
was functionalized by Suzuki coupling.
a
Scheme 2. Synthesis of 2-Benzyl Quinazolinones
EXPERIMENTAL SECTION
■
Unless otherwise stated, commercially available reagents and solvents
were used without further purification. Yields were not optimized.
NMR experiments were performed on a BrukerAvance 500 MHz
spectrometer using an internal deuterium lock. Chemical shifts were
measured in parts per million (ppm) relative to the residual signal of
the deuterated solvent. Data are presented in the following format:
chemical shift (multiplicity [s = singlet, d = doublet, t = triplet, q =
quartet, p = pentet, m = multiplet, and br = broad], coupling
constants (J in Hz), integration). Where mixed solvent systems were
used residual solvent peaks to which the spectra are referenced are
underlined. Assignment of 13C NMR data was achieved through
analysis of 2D NMR spectra (HSQC, HMBC, COSY, and NOSEY).
LCMS analyses and high resolution mass spectrometry were
performed on an Agilent 1200 series HPLC and diode array detector
coupled to a 6210 time-of-flight mass spectrometer with dual
multimode APCI/ESI source (methods A and B) or a Waters
Acquity UPLC and diode array detector coupled to a Waters G2
QToF mass spectrometer fitted with a multimode ESI/APCI source
(method C); see Supporting Information for method details. All
a
(a) (i) 50% NH2OH(aq), 120 °C, (ii) 25, 150 °C, 24%; (b)
PdCl2(PPh3)2, NaOH(aq), 1,4-dioxane, 100 °C, 51−100%.
Isoquinolinones were prepared by a Doebner-modified
Knoevenagel condensation with 4-bromo-3-methylbenzalde-
hyde, leading to 27 (Scheme 3).18 Preparation of a mixed
anhydride with ethyl chloroformate followed by treatment with
sodium azide gave 28, and subsequent Curtius rearrangement
allowed for intramolecular trapping of the isocyanate to yield a
3:2 mixture of isoquinolinone regioisomers (29 and 30). After
F
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compounds described herein exhibited spectral data consistent with
their proposed structures and, with the exception of 6 (purity >90%),
had purities >95% as determined by HPLC.
General Procedure 1: Multicomponent Reaction. A mixture
of an anthranillic acid or isatoic anhydride (1.0 equiv), amine (1.0
equiv), and orthoester (1.0 equiv) was stirred for 1−16 h at 110 °C,
until LCMS indicated that reaction was complete. The mixture was
cooled to RT, and the product was purified either by crystallization or
trituration with hot EtOH unless otherwise indicated.
dimethylbenzene-1,4-diamine (565 mg; 4.15 mmol; 1.0 equiv), and
triethoxymethane (615 mg; 4.15 mmol; 1.0 equiv) were used to yield
6-bromo-3-(4-(dimethylamino)phenyl)quinazolin-4(3H)-one (833
mg; 2.43 mmol; 59%) as a glittery, dark-purple solid. 1H NMR
(500 MHz, CDCl3) δ 8.50 (d, J = 2.3 Hz, 1H), 8.14 (s, 1H), 7.87 (dd,
J = 8.7, 2.3 Hz, 1H), 7.64 (d, J = 8.6 Hz, 1H), 7.26−7.22 (m, 2H),
6.84−6.79 (m, 2H), 3.04 (s, 6H). 13C NMR (126 MHz, CDCl3) δ
160.13, 150.74, 147.30, 146.84, 137.46, 129.70, 129.30, 127.41,
125.62, 123.88, 120.99, 112.49, 40.46. HRMS (ESI) m/z calc
C16H15BrN3O [M + H]+ 344.0393; found = 344.0403.
6-Bromo-3-(4-morpholinophenyl)quinazolin-4(3H)-one, i.
Following general procedure 1, 6-bromo-2H-benzo[d][1,3]oxazine-
2,4(1H)-dione (1.00 g; 4.15 mmol; 1.0 equiv), 4-morpholinoaniline
(740 mg; 4.15 mmol; 1.0 equiv), and triethoxymethane (940 mg; 4.15
mmol; 1.0 equiv) were used to yield 6-bromo-3-(4-
morpholinophenyl)quinazolin-4(3H)-one (1.59 g; 4.13 mmol;
6-Bromo-2-methylquinazolin-4(3H)-one, vi. 6-Bromo-2H-
benzo[d][1,3]oxazine-2,4(1H)-dione (1.00 g; 4.15 mmol; 1.0
equiv), NH4OAc (385 mg; 5.00 mmol; 1.2 equiv), and triethoxy-
methane (673 mg; 4.15 mmol; 1.0 equiv) were stirred at 110 °C for
18 h. The crude reaction product was loaded onto silica using CH2Cl2
and purified by column chromatography with a solvent system of 0−
8% MeOH in CH2Cl2. 6-Bromo-2-methylquinazolin-4(3H)-one (212
1
100%) as a light purple solid. H NMR (500 MHz, CDCl3) δ 8.41
(d, J = 2.3 Hz, 1H), 8.08 (s, 1H), 7.84 (dd, J = 8.6, 2.3 Hz, 1H), 7.59
(d, J = 8.6 Hz, 1H), 7.26−7.23 (m, 2H), 7.00−6.97 (m, 2H), 3.86−
3.82 (m, 4H), 3.21−3.18 (m, 4H). 13C NMR (126 MHz, CDCl3) δ
160.07, 151.65, 147.00, 146.44, 137.80, 129.57, 129.04, 128.43,
127.52, 123.54, 121.30, 115.86, 66.64, 48.63. HRMS (ESI) m/z calc
C18H17BrN3O2 [M + H]+ 386.0499; found = 386.0501.
1
mg; 0.891 mmol; 21%) was isolated as a cream solid. H NMR (500
MHz, CDCl3/MeOH) δ 8.28 (d, J = 2.3 Hz, 1H), 7.76 (dd, J = 8.7,
2.4 Hz, 1H), 7.45 (d, J = 8.7 Hz, 1H), 2.40 (s, 3H). 13C NMR (126
MHz, CDCl3/MeOH) δ 161.87, 154.36, 147.56, 137.82, 128.72,
128.20, 121.88, 119.82, 21.36. HRMS (ESI) m/z calc C9H8BrN2O [M
+ H]+ 238.9815; found = 238.9822.
6-Bromo-3-phenylquinazolin-4(3H)-one, ii. 6-Bromo-2H-
benzo[d][1,3]oxazine-2,4(1H)-dione (1.00 g; 4.15 mmol; 1.0
equiv), aniline (379 μL; 4.15 mmol; 1.0 equiv), and triethoxymethane
(615 mg; 4.15 mmol; 1.0 equiv) were stirred at 110 °C for 18 h. The
resulting tar was loaded onto silica with CH2Cl2 and purified by
column chromatography in a solvent system of 0−5% MeOH in
CH2Cl2. 6-Bromo-3-phenylquinazolin-4(3H)-one (387 mg; 1.29
6-Bromo-2,5-dimethylquinazolin-4(3H)-one, vii. 6-Amino-3-
bromo-2-methylbenzoic acid (950 mg; 4.15 mmol; 1.0 equiv),
NH4OAc (385 mg; 5.00 mmol; 1.2 equiv) and triethoxymethane
(673 mg; 4.15 mmol; 1.0 equiv) were stirred at 110 °C for 48 h. The
crude reaction product was loaded onto silica using CH2Cl2 and
purified by column chromatography with a solvent system of 0−8%
MeOH in CH2Cl2. 6-Bromo-2,5-dimethylquinazolin-4(3H)-one (255
1
mmol; 31%) was obtained as a beige solid. H NMR (500 MHz,
1
mg; 1.01 mmol; 24%) was isolated as a cream solid. H NMR (500
CDCl3) δ 8.51 (d, J = 2.2 Hz, 1H), 8.15 (s, 1H), 7.90 (dd, J = 8.7, 2.3
Hz, 1H), 7.66 (d, J = 8.6 Hz, 1H), 7.60−7.56 (m, 2H), 7.55−7.51 (m,
1H), 7.45−7.42 (m, 2H). 13C NMR (126 MHz, CDCl3) δ 159.61,
146.75, 146.41, 137.79, 137.19, 129.76, 129.74, 129.43, 129.34,
126.91, 123.79, 121.34. HRMS (ESI) m/z calc C14H10BrN2O [M +
H]+ 300.9971; found = 300.9977.
MHz, CDCl3/MeOH) δ 7.77 (dd, J = 8.8, 1.5 Hz, 1H), 7.25 (d, J =
8.3 Hz, 1H), 2.90 (s, 3H), 2.33 (s, 3H). 13C NMR (126 MHz,
CDCl3/MeOH) δ 166.76, 157.95, 153.44, 143.71, 142.04, 129.43,
127.89, 124.22, 25.22, 24.73. HRMS (ESI) m/z calc C10H10BrN2O
[M + H]+ 252.9971; found = 252.9980.
6-Bromo-3-cyclohexylquinazolin-4(3H)-one, iii. 6-Bromo-2H-
benzo[d][1,3]oxazine-2,4(1H)-dione (1.00 g; 4.15 mmol; 1.0 equiv),
cyclohexanamine (475 μL; 4.15 mmol; 1.0 equiv) and triethoxy-
methane (615 mg; 4.15 mmol; 1.0 equiv) were stirred at 110 °C for
18 h. The resulting tar was loaded onto silica with CH2Cl2 and
purified by column chromatography in a solvent system of 0−5%
MeOH in CH2Cl2. 6-Bromo-3-phenylquinazolin-4(3H)-one (429 mg;
1.40 mmol; 34%) was obtained as a light yellow solid. 1H NMR (500
MHz, CDCl3) δ 8.45 (d, J = 2.2 Hz, 1H), 8.13 (s, 1H), 7.83 (dd, J =
8.7, 2.3 Hz, 1H), 7.58 (d, J = 8.7 Hz, 1H), 4.81 (tt, J = 12.3, 3.7 Hz,
1H), 2.05−1.99 (m, 2H), 1.99−1.93 (m, 2H), 1.81 (ddtd, J = 14.7,
4.9, 3.2, 1.4 Hz, 1H), 1.71−1.59 (m, 2H), 1.54 (qt, J = 13.2, 3.3 Hz,
2H), 1.28 (qt, J = 13.0, 3.7 Hz, 1H). 13C NMR (126 MHz, CDCl3) δ
159.55, 146.38, 144.22, 137.29, 129.52, 129.11, 123.33, 120.68, 53.65,
32.58, 25.86, 25.24. HRMS (ESI) m/z calc C14H16BrN2O [M + H]+
307.0441; found = 307.0448.
6-Bromo-3-(3-morpholinopropyl)quinazolin-4(3H)-one, iv.
6-Bromo-2H-benzo[d][1,3]oxazine-2,4(1H)-dione (1.0 g; 4.15
mmol; 1.0 equiv), 3-morpholinopropan-1-amine (598 mg; 4.15
mmol; 1.0 equiv), and triethoxymethane (940 mg; 6.35 mmol; 1.5
equiv) were stirred at 110 °C for 5 h. The resulting tar was loaded
onto silica with CH2Cl2 and purified by column chromatography in a
solvent system of 0−8% MeOH in CH2Cl2 to yield 6-bromo-3-(3-
morpholinopropyl)quinazolin-4(3H)-one (1.06 g; 3.02 mmol; 73%)
as a yellow oil. 1H NMR (500 MHz, DMSO) δ 8.43 (s, 1H), 8.22 (d,
J = 2.4 Hz, 1H), 7.96 (dd, J = 8.7, 2.4 Hz, 1H), 7.63 (d, J = 8.7 Hz,
1H), 4.02 (t, J = 6.9 Hz, 2H), 3.44 (t, J = 4.7 Hz, 4H), 2.31 (t, J = 6.6
Hz, 2H), 2.27 (br-s, 4H), 1.86 (p, J = 6.7 Hz, 2H). 13C NMR (126
MHz, DMSO) δ 159.68, 149.44, 147.48, 137.47, 130.02, 128.52,
123.66, 119.77, 66.52, 55.58, 53.50, 45.53, 24.79. HRMS (ESI) m/z
calc C15H19BrN3O2 [M + H]+ 352.0655; found = 352.0636.
6-Bromo-2-ethyl-5-methylquinazolin-4(3H)-one, viii. 6-
Amino-3-bromo-2-methylbenzoic acid (950 mg; 4.15 mmol; 1.0
equiv), NH4OAc (385 mg; 5.00 mmol; 1.2 equiv), and triethyl
orthopropionate (731 mg; 4.15 mmol; 1.0 equiv) were stirred at 110
°C for 48 h. The crude reaction product was loaded onto silica using
CH2Cl2 and purified by column chromatography with a solvent
system of 0−8% MeOH in CH2Cl2. 6-Bromo-2-ethyl-5-methylquina-
zolin-4(3H)-one (418 mg; 1.57 mmol; 38%) was isolated as an off-
white solid. 1H NMR (500 MHz, DMSO) δ 12.17 (s, 1H), 7.91 (d, J
= 8.7 Hz, 1H), 7.36 (d, J = 8.7 Hz, 1H), 2.92 (s, 3H), 2.58 (q, J = 7.5
Hz, 2H), 1.23 (t, J = 7.5 Hz, 3H). 13C NMR (126 MHz, DMSO) δ
162.45, 159.18, 150.45, 138.98, 137.79, 127.17, 122.94, 121.18, 27.87,
21.54, 11.57. HRMS (ESI) m/z calc C11H12BrN2O [M + H]+
267.0128; found = 267.0135.
4-Bromo-3-cyclopropyl-1-tosyl-1H-pyrazole, ix. To a solution
of 4-bromo-3-cyclopropyl-1H-pyrazole (100 mg; 0.538 mmol; 1.0
equiv) in CH2Cl2 (10 mL; 0.054 M) was added NaOH(aq) (118 μL; 5
M; 0.591 mmol; 1.1 equiv) and 4-toluenesulfonyl chloride (113 mg;
0.591 mmol; 1.1 equiv). The mixture was heated to reflux and stirred
for 72 h before being diluted with water (400 mL) and extracted with
CH2Cl2 (2 × 200 mL). The combined organic portions were washed
with brine, dried (Na2SO4), and filtered, and solvent was removed
under reduced pressure. The crude product was washed through an
SCX-II column with MeOH to yield 4-bromo-3-cyclopropyl-1-tosyl-
1H-pyrazole (103 mg; 0.303 mmol; 56%) as a white solid after
removal of solvent under reduced pressure. 1H NMR (500 MHz,
DMSO) δ 8.68 (s, 1H), 7.86−7.81 (m, 2H), 7.48 (d, J = 8.1 Hz, 2H),
2.40 (s, 3H), 1.84 (tt, J = 8.3, 4.9 Hz, 1H), 0.99−0.93 (m, 2H), 0.78−
0.73 (m, 2H). 13C NMR (126 MHz, DMSO) δ 158.61, 146.80,
133.46, 133.17, 130.88, 128.12, 99.30, 21.64, 8.83, 7.76. HRMS (ESI)
m/z calc C13H13BrN2O2SNa [M + Na]+ 362.9779; found = 362.9771.
4-Bromo-3-ethyl-1-tosyl-1H-pyrazole, x. p-Toluene sulfonyl
chloride (194 mg; 1.02 mmol; 1.1 equiv) was added to a solution of
4-bromo-3-ethyl-1H-pyrazole (162 mg; 0.930 mmol; 1.0 equiv) and
6-Bromo-3-(4-(dimethylamino)phenyl)quinazolin-4(3H)-
one, v. Following general procedure 1, 6-bromo-2H-benzo[d][1,3]-
oxazine-2,4(1H)-dione (1.0 g; 4.15 mmol; 1.0 equiv), N1,N1-
G
DOI: 10.1021/acs.jmedchem.8b00782
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Journal of Medicinal Chemistry
Article
[5 M] NaOH solution (0.2 mL; 1.02 mmol; 1.1 equiv) in CH2Cl2
(18.5 mL), and the mixture was stirred at 38 °C. After 16 h the
reaction mixture was washed with water (15 mL) and the aqueous
layer was extracted with CH2Cl2 (2 × 20 mL). The combined organic
fractions were washed with brine, dried over MgSO4, filtered, and
concentrated under vacuum. The crude mixture was purified by
normal phase flash chromatography in a solvent system of 0−5%
EtOAc in cyclohexane to afford 4-bromo-3-ethyl-1-tosyl-1H-pyrazole
mg; 0.214 mmol; 1.1 equiv), and PdCl2(PPh3)2 (6.8 mg; 9.70 μmol;
0.05 equiv) were charged to a microwave vial. The vial was sealed and
purged of air with avacuum and N2 five times. 1,4-Dioxane (4.4 mL;
0.044 M) was added, and the mixture was heated at 120 °C for 1 h
under microwave irradiation. At RT, 6-bromoquinazolin-4(3H)-one
(44 mg; 0.194 mmol; 1.0 equiv), [0.5 M] Na2CO3(aq) (389 μL; 0.194
mmol; 1.0 equiv), and PdCl2(PPh3)2 (6.8 mg; 9.70 μmol; 0.05 equiv)
were added to the reaction mixture before the vial was sealed and
purged of air with vacuum and N2 five times. The mixture was heated
to 120 °C for 1 h under microwave irradiation. The mixture was then
diluted with water (100 mL) and extracted with CH2Cl2 (3 × 75 mL).
Combined organic portions were washed with brine (100 mL), dried
(Na2SO4), and filtered, and solvent was removed under reduced
pressure. The crude product was purified by column chromatography
in a solvent system of 2−15% MeOH in CH2Cl2 to yield 6-(3-ethyl-1-
tosyl-1H-pyrazol-4-yl)quinazolin-4(3H)-one (13 mg; 0.03 mmol;
15%) as a white solid. A solution of the tosyl-protected intermediate
was formed in EtOH (1.1 mL), to which was added [1 M] NaOH(aq)
(0.8 mL; 0.82 mmol). The mixture was stirred at 50 °C for 14 h and
then neutralized using 1 M HCl and purified by SCX-2
chromatography (2 g, 10 mL MeOH then 30 mL 1 M NH3 in
MeOH). The crude mixture was further purified by Biotage column
chromatography (5−12% MeOH in DCM) and concentrated under a
vacuum. The resulting solid was triturated with n-hexane (3 × 1 mL)
to afford 6-(3-ethyl-1H-pyrazol-4-yl)quinazolin-4(3H)-one (7 mg,
0.025 mmol, 82%) as an off-white solid. 1H NMR (500 MHz,
DMSO) δ 12.77 (s, 1H), 12.25 (s, 1H), 8.09 (d, J = 2.1 Hz, 1H), 8.06
(d, J = 3.4 Hz, 1H), 7.90 (dd, J = 8.4, 2.2 Hz, 1H), 7.68 (d, J = 8.5 Hz,
1H), 2.82 (t, J = 7.6 Hz, 2H), 1.22 (t, J = 7.6 Hz, 4H). 13C NMR (126
MHz, DMSO) δ 161.18, 147.14, 145.16, 133.73, 132.92, 128.12,
123.32, 122.97, 18.25, 13.86. HRMS (ESI) m/z calc C13H13N4O [M
+ H]+ 241.1084; found = 241.1084.
1
(246 mg; 0.826 mmol; 81%) as a white solid. H NMR (500 MHz,
CDCl3) δ 8.03 (s, 1H), 7.85−7.93 (m, 2H), 7.30−7.38 (m, 2H), 2.62
(q, J = 7.6, 2H), 2.44 (s, 3H), 1.22 (t, J = 7.6, 3H). 13C NMR (126
MHz, CDCl3) δ 158.69, 145.92, 133.86, 128.13, 98.52, 21.74, 20.38,
12.23. HRMS (ESI) m/z calc C12H14BrN2O2S [M + H]+ 328.9954;
found = 328.9954.
General Procedure 2: Suzuki Coupling. To a Biotage
microwave vial was added the required bromo-aryl (1.0 equiv),
boronic acid or ester (1.0−1.2 equiv), PdCl2(PPh3)2 (0.05 equiv),
Na2CO3(aq) (0.5 M; 1.0 equiv), and 1,4-dioxane or DME. The vial was
sealed and purged of air with 3 rounds of vacuum and N2 or Ar. The
mixture was heated to 120−150 °C for 1 h under microwave
irradiation. The reaction mixture was filtered through Celite, washed
with water, and extracted twice with CH2Cl2. Combined organic
portions were dried (Na2SO4), filtered, and had solvent removed
under reduced pressure. The crude product was purified by column
chromatography in a solvent system of MeOH in CH2Cl2.
6-(1H-Pyrazol-4-yl)quinazolin-4(3H)-one, 1. Following general
procedure 2, 6-bromoquinazolin-4(3H)-one (44 mg; 0.20 mmol) was
reacted with [1-(tert-butoxycarbonyl)-1H-pyrazol-4-yl]boronic acid
pinacol ester (69 mg; 0.24 mmol) in DME to yield 6-(1H-pyrazol-4-
yl)quinazolin-4(3H)-one (22 mg; 54%) as an off-white solid. Reaction
temperature: 150 °C. Purification: 1−8% MeOH in CH2Cl2. 1H
NMR (500 MHz, DMSO) 13.06 (br-s, 1H), 12.21 (br-s, 1H), 8.38
(br-s, 1H), 8.28 (d, J = 2.2 Hz, 1H), 8.08 (dd, J = 8.4, 2.2 Hz, 1H),
8.05 (s, 1H), 8.04 (br-s, 1H), 7.65 (d, J = 8.4 Hz, 1H). 13C NMR
(126 MHz, DMSO) 161.2, 147.4, 145.0, 136.9, 132.1, 128.2, 126.6,
123.5, 121.3, 120.6. HRMS (ESI) m/z calc C11H9N4O [M + H]+
213.0771; found = 213.0779.
6-(1-Methyl-1H-pyrazol-4-yl)quinazolin-4(3H)-one, 2. Fol-
lowing general procedure 2, 6-bromoquinazolin-4(3H)-one (47 mg;
0.21 mmol) was reacted with 1-methylpyrazole-4-boronic acid pinacol
ester (52 mg; 0.25 mmol) in DME to yield 6-(1-methyl-1H-pyrazol-4-
yl)quinazolin-4(3H)-one (42 mg; 88%) as a white solid. Reaction
temperature: 150 °C. Purification: 1−8% MeOH in CH2Cl2. 1H
NMR (500 MHz, DMSO) 12.2 (br-s, 1H), 8.32 (d, J = 0.9 Hz, 1H),
8.23 (d, J = 2.1 Hz, 1H), 8.04 (br-s, 1H), 8.02 (dd, J = 8.5, 2.2 Hz,
1H), 7.99 (d, J = 0.9 Hz, 1H), 7.65 (d, J = 8.5 Hz, 1H), 3.88 (s, 3H).
13C NMR (126 MHz, DMSO) 161.2, 147.4, 145.0, 136.8, 131.8,
128.9, 128.3, 123.6, 121.1, 121.1, 39.2. HRMS (ESI) m/z calc
C12H11N4O [M + H]+ 227.0927; found = 227.0924.
6-(3-Methyl-1H-pyrazol-4-yl)quinazolin-4(3H)-one, 3. Fol-
lowing general procedure 2, 6-bromoquinazolin-4(3H)-one (31 mg;
0.14 mmol) was reacted with 3-methyl-1H-pyrazole-4-boronic acid
pinacol ester (35 mg; 0.17 mmol) and Pd(PPh3)4 (11 mg; 7 mol %)
in DME. After 40 min, additional 3-methyl-1H-pyrazole-4-boronic
acid pinacol ester (29 mg; 0.14 mmol) and Pd(PPh3)4 (8 mg; 0.05
equiv) were added, and the mixture was stirred under microwave
irradiation at 150 °C for 30 min. After this time, the reaction was
purified by SCX-2 chromatography (2 g, 30 mL MeOH then 30 mL 1
M ammonia in MeOH) and column chromatography (10 g SNAP, 3-
9% MeOH in CH2Cl2) to afford 6-(3-methyl-1H-pyrazol-4-yl)-
quinazolin-4(3H)-one (14 mg; 44%) as a cream solid. 1H NMR
(500 MHz, DMSO) δ 12.75 (d, J = 41.8 Hz, 1H), 12.24 (s, 1H), 8.11
(s, 1H), 8.06 (d, J = 3.3 Hz, 1H), 7.94 (dd, J = 8.3, 2.2 Hz, 1H), 7.81
(s, 1H), 7.68 (d, J = 8.5 Hz, 1H), 2.42 (d, J = 30.9 Hz, 3H). 13C NMR
(126 MHz, DMSO) δ 161.19, 147.06, 145.11, 138.75, 135.75, 133.27,
132.88, 128.14, 123.32, 122.47, 117.15, 11.13. HRMS (ESI) m/z calc
C12H11N4O [M + H]+ 227.0927; found = 227.0933.
6-(3-Cyclopropyl-1H-pyrazol-4-yl)quinazolin-4(3H)-one, 5.
4-Bromo-3-cyclopropyl-1-tosyl-1H-pyrazole (30 mg; 0.0882 mmol;
1.0 equiv), KOAc (26 mg; 0.265 mmol; 1.1 equiv), bis(pinacolato)-
diboron (25 mg; 0.0971 mmol; 1.1 equiv), and PdCl2(PPh3)2 (3.1
mg; 4.41 μmol; 0.05 equiv) were charged to a microwave vial. The
vial was sealed and purged of air with a vacuum and N2 five times. 1,4-
Dioxane (2 mL; 0.044 M) was added, and the mixture was heated at
120 °C for 1 h under microwave irradiation. 6-Bromoquinazolin-
4(3H)-one (20 mg; 0.0882 mmol; 1.0 equiv), [0.5 M] Na2CO3(aq)
(176 μL; 0.0882 mmol; 1.0 equiv), and PdCl2(PPh3)2 (3.1 mg; 4.41
μmol; 0.05 equiv) were added to the reaction mixture (<40 °C)
before the vial was sealed and purged of air with a vacuum and N2 five
times. The mixture was heated to 120 °C for 1 h under microwave
irradiation. The mixture was diluted with water (100 mL) and
extracted with CH2Cl2 (3 × 75 mL). The combined organic portions
were washed with brine (100 mL), dried (Na2SO4) and filtered and
solvent was removed under reduced pressure. The crude intermediate
was purified by column chromatography in a solvent system of 2−
15% MeOH in CH2Cl2 to yield 6-(3-cyclopropyl-1-tosyl-1H-pyrazol-
4-yl)quinazolin-4(3H)-one (31 mg; 0.0763 mmol; 87%) as a white
solid. A mixture of 6-(3-cyclopropyl-1-tosyl-1H-pyrazol-4-yl)-
quinazolin-4(3H)-one (5 mg; 0.0123 mmol; 1.0 equiv), [1 M]
NaOH(aq) (308 μL; 0.308 mmol; 25 equiv), and EtOH (1 mL; 0.012
M) was heated at 50 °C for 2 h before being cooled to RT and
neutralized with [1 M] HCl(aq). The mixture had solvent removed
under reduced pressure, and the residue was purified by column
chromatography in a solvent system of 2−10% MeOH in CH2Cl2. 6-
(3-Cyclopropyl-1H-pyrazol-4-yl)quinazolin-4(3H)-one (2.1 mg;
1
0.00833 mmol; 68%) was isolated as a white solid. H NMR (500
MHz, MeOD) δ 8.49 (q, J = 2.1 Hz, 1H), 8.12 (d, J = 8.6 Hz, 1H),
8.10 (s, 1H), 7.87 (s, 1H), 7.75 (d, J = 8.4 Hz, 1H), 2.13−2.06 (m,
1H), 1.12−0.82 (m, 4H). 13C NMR (126 MHz, MeOD) δ 161.90,
146.50, 144.37, 133.76, 133.02, 128.41, 126.83, 125.55, 123.26,
122.52, 118.86, 6.36, 6.35. HRMS (ESI) m/z calc C14H13N4O [M +
H]+ 253.1084; found = 253.1089.
6-(3-Ethyl-1H-pyrazol-4-yl)quinazolin-4(3H)-one, 4. 4-
Bromo-3-ethyl-1-tosyl-1H-pyrazole (66 mg; 0.194 mmol; 1.0 equiv),
KOAc (57 mg; 0.583 mmol; 1.1 equiv), bis(pinacolato)diboron (55
6-(3,5-Dimethyl-1H-pyrazol-4-yl)quinazolin-4(3H)-one, 6.
Following general procedure 2, 6-bromoquinazolin-4(3H)-one (37
mg; 0.165 mmol; 1 equiv) was reacted with 3,5-dimethyl-1H-
H
DOI: 10.1021/acs.jmedchem.8b00782
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Journal of Medicinal Chemistry
Article
pyrazole-4-boronic acid pinacol ester (43 mg; 0.194 mmol; 1.2 equiv)
in DME (1.00 mL; 0.16 M) were reacted to yield 6-(3,5-dimethyl-1H-
pyrazol-4-yl)quinazolin-4(3H)-one (19 mg; 0.0792 mmol; 50%) as a
white solid. Reaction temperature: 150 °C. Purification: 4−11%
mmol; 1.0 equiv), PdCl2(PPh3)2 (4.4 mg; 0.0063 mmol; 0.05 equiv),
6-bromo-5-methylquinazolin-4(3H)-one (30 mg; 0.126 mmol; 1.0
equiv), [0.5 M] Na2CO3(aq) (252 μL; 0.126 mmol; 1.0 equiv) and 1,4-
dioxane (2 mL; 0.063 M) were used to yield 5-methyl-6-(quinolin-4-
yl)quinazolin-4(3H)-one (18 mg; 0.0627 mmol; 50%) as a white
solid. Reaction temperature: 120 °C. Purification: 3−20% MeOH in
1
MeOH in CH2Cl2. H NMR (500 MHz, DMSO) δ 12.17 (s, 1H),
8.11 (d, J = 8.4 Hz, 1H), 8.08 (d, J = 3.5 Hz, 1H), 7.77 (s, 1H), 7.64
(d, J = 1.7 Hz, 1H), 7.59 (dd, J = 8.2, 1.8 Hz, 1H), 3.81 (s, 3H), 2.45
(s, 3H). 13C NMR (126 MHz, DMSO) δ 160.95, 149.73, 146.12,
140.30, 137.33, 136.47, 126.77, 126.12, 124.50, 120.49, 118.82, 36.90,
10.91. HRMS (ESI) m/z calc C13H13N4O [M + H]+ 241.1084; found
= 241.1081.
1
CH2Cl2. H NMR (500 MHz, CDCl3) δ 8.87 (d, J = 4.4 Hz, 1H),
8.13−8.10 (m, 1H), 7.96 (d, J = 3.7 Hz, 1H), 7.70 (ddd, J = 8.4, 6.8,
1.6 Hz, 1H), 7.62 (d, J = 8.2 Hz, 1H), 7.53−7.51 (m, 1H), 7.43 (ddd,
J = 8.1, 6.7, 1.2 Hz, 1H), 7.37 (dd, J = 8.4, 1.5 Hz, 1H), 7.30−7.25
(m, 1H), 2.49 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 162.63,
150.23, 149.54, 148.41, 147.68, 144.71, 139.31, 136.93, 135.28,
129.98, 129.03, 127.89, 127.22, 125.67, 125.05, 121.85, 121.58, 19.67.
HRMS (ESI) m/z calc C18H14N3O [M + H]+ 288.1132; found =
288.1144.
5-Methyl-6-(quinolin-5-yl)quinazolin-4(3H)-one, 11. Follow-
ing general procedure 2, quinolin-5-ylboronic acid (22 mg; 0.126
mmol; 1.0 equiv), PdCl2(PPh3)2 (4.4 mg; 0.0063 mmol; 0.05 equiv),
6-bromo-5-methylquinazolin-4(3H)-one (30 mg; 0.126 mmol; 1.0
equiv), [0.5 M] Na2CO3(aq) (252 μL; 0.126 mmol; 1.0 equiv) and 1,4-
dioxane (2 mL; 0.063 M) were used to yield 5-methyl-6-(quinolin-5-
yl)quinazolin-4(3H)-one (21 mg; 0.0731 mmol; 58%) was isolated as
a white solid. Reaction temperature: 120 °C. Purification: 3−20%
MeOH in CH2Cl2. 1H NMR (500 MHz, CDCl3) δ 8.86 (dd, J = 4.2,
1.7 Hz, 1H), 8.13 (dt, J = 8.6, 1.1 Hz, 1H), 7.97 (s, 1H), 7.79 (dd, J =
8.6, 7.0 Hz, 1H), 7.76−7.72 (m, 1H), 7.64 (d, J = 8.3 Hz, 1H), 7.58
(d, J = 8.3 Hz, 1H), 7.42 (dd, J = 7.0, 1.2 Hz, 1H), 7.33 (dd, J = 8.5,
4.2 Hz, 1H), 2.50 (s, 3H). 13C NMR (126 MHz, CDCl3) δ 162.37,
150.09, 147.72, 144.30, 139.89, 139.20, 138.41, 137.77, 136.31,
134.56, 129.33, 128.66, 127.78, 127.18, 125.01, 121.43, 120.96, 19.70.
HRMS (ESI) m/z calc C18H14N3O [M + H]+ 288.1132; found =
288.1138.
3-Methyl-6-(quinolin-4-yl)quinazolin-4(3H)-one, 12. Follow-
ing general procedure 2, quinolin-4-ylboronic acid (25 mg; 0.144
mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721 mmol; 0.05 equiv),
6-bromo-3-methylquinazolin-4(3H)-one (34 mg; 0.144 mmol; 1.0
equiv), [0.5 M] Na2CO3(aq) (288 μL; 0.144 mmol; 1.0 equiv), and
1,4-dioxane (2 mL; 0.072 M) were used to yield 3-methyl-6-
(quinolin-4-yl)quinazolin-4(3H)-one (27 mg; 0.0940 mmol; 65%) as
a white solid. Reaction temperature: 130 °C. Purification: 0−8%
MeOH in CH2Cl2. 1H NMR (500 MHz, CDCl3/MeOD) δ 8.77 (d, J
= 4.6 Hz, 1H), 8.31 (d, J = 2.0 Hz, 1H), 8.09 (s, 1H), 8.04−7.99 (m,
1H), 7.79 (dd, J = 8.3, 2.0 Hz, 1H), 7.74 (d, J = 8.5 Hz, 2H), 7.64 (t, J
= 7.6 Hz, 2H), 7.46−7.39 (m, 1H), 7.31 (d, J = 4.6 Hz, 1H), 3.52 (s,
3H). 13C NMR (126 MHz, CDCl3) δ 161.50, 149.40, 149.35, 147.93,
147.87, 147.51, 136.90, 135.46, 129.96, 128.89, 127.45, 127.33,
127.27, 126.40, 125.33, 121.84, 121.57, 34.11. HRMS (ESI) m/z calc
C18H14N3O [M + H]+ 288.1132; found = 288.1124.
3-Methyl-6-(quinolin-5-yl)quinazolin-4(3H)-one, 13. Follow-
ing general procedure 2, quinolin-5-ylboronic acid (25 mg; 0.144
mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721 mmol; 0.05 equiv),
6-bromo-3-methylquinazolin-4(3H)-one (34 mg; 0.144 mmol; 1.0
equiv), [0.5 M] Na2CO3(aq) (288 μL; 0.144 mmol; 1.0 equiv), and
1,4-dioxane (2 mL; 0.072 M) were used to yield 3-methyl-6-
(quinolin-5-yl)quinazolin-4(3H)-one (23 mg; 0.0801 mmol; 56%) as
a white solid. Reaction temperature: 130 °C. Purification: 0−8%
MeOH in CH2Cl2. 1H NMR (500 MHz, CDCl3/MeOD) δ 8.78 (dd,
J = 4.2, 1.7 Hz, 1H), 8.30 (d, J = 1.8 Hz, 1H), 8.14 (ddd, J = 8.6, 1.8,
1.0 Hz, 1H), 8.10 (d, J = 1.4 Hz, 1H), 8.04 (dt, J = 8.5, 1.1 Hz, 1H),
7.78 (dd, J = 8.3, 2.0 Hz, 1H), 7.75 (d, J = 8.4 Hz, 1H), 7.72 (dd, J =
8.6, 7.1 Hz, 1H), 7.49 (dd, J = 7.1, 1.3 Hz, 1H), 7.34 (ddd, J = 8.7,
4.3, 1.3 Hz, 1H), 3.56 (d, J = 1.4 Hz, 3H).13C NMR (126 MHz,
CDCl3/MeOD) δ 161.58, 149.90, 147.74, 147.49, 147.29, 138.73,
138.44, 136.10, 134.47, 129.30, 128.63, 127.92, 127.44, 127.29,
126.47, 121.74, 121.45, 34.11. HRMS (ESI) m/z calc C18H14N3O [M
+ H]+ 288.1132; found = 288.113.
6-(Quinolin-4-yl)quinazolin-4(3H)-one, 7. Following general
procedure 2, quinolin-4-ylboronic acid (44 mg; 0.255 mmol 1.0
equiv), 6-bromoquinazolin-4(3H)-one (57 mg; 0.255 mmol; 1.0
equiv), PdCl2(PPh3)2 (9 mg; 0.0128 mmol; 0.05 equiv), [0.5 M]
Na2CO3 (510 μL; 0.255 mmol; 1.0 equiv) and 1,4-dioxane (1.28 mL;
0.20 M) were used to yield 6-(quinolin-4-yl)quinazolin-4(3H)-one
(38 mg; 0.139 mmol; 55%) as a white solid. Reaction temperature:
120 °C. Purification: 1−8% MeOH in CH2Cl2. 1H NMR (500 MHz,
MeOH) δ 8.91 (d, J = 4.5 Hz, 1H), 8.43 (d, J = 1.9 Hz, 1H), 8.18−
8.12 (m, 1H), 8.12 (s, 1H), 7.97 (dd, J = 8.4, 2.1 Hz, 1H), 7.91 (dd, J
= 8.4, 1.3 Hz, 1H), 7.90 (d, J = 8.5 Hz, 1H), 7.83−7.79 (m, 1H),
7.62−7.57 (m, 1H), 7.49 (d, J = 4.5 Hz, 1H). 13C NMR (126 MHz,
MeOD/CDCl3) δ 161.70, 149.36, 148.78, 148.01, 147.77, 145.49,
136.86, 135.75, 130.05, 128.81, 127.59, 127.41, 127.22, 126.51,
125.43, 122.97, 121.65. HRMS (ESI) m/z calc C17H12N3O [M + H]+
274.0975; found = 274.0985.
6-(Quinolin-5-yl)quinazolin-4(3H)-one, 8. Following general
procedure 2, quinolin-5-ylboronic acid (44 mg; 0.255 mmol 1.0
equiv), 6-bromoquinazolin-4(3H)-one (57 mg; 0.255 mmol; 1.0
equiv), PdCl2(PPh3)2 (9 mg; 0.0128 mmol; 0.05 equiv), [0.5 M]
Na2CO3 (510 μL; 0.255 mmol; 1.0 equiv) and 1,4-dioxane (1.28 mL;
0.20 M) were used to yield 6-(quinolin-5-yl)quinazolin-4(3H)-one
(40 mg; 0.146 mmol; 57%) as a white solid. Reaction temperature:
120 °C. Purification: 1−8% MeOH in CH2Cl2. 1H NMR (500 MHz,
MeOD/CDCl3) δ 8.88 (dd, J = 4.2, 1.6 Hz, 1H), 8.40−8.35 (m, 1H),
8.29 (ddd, J = 8.6, 1.7, 0.9 Hz, 1H), 8.13 (dt, J = 8.6, 1.1 Hz, 1H),
8.11 (s, 1H), 7.93 (dd, J = 8.4, 2.1 Hz, 1H), 7.87 (d, J = 8.3 Hz, 1H),
7.85 (dd, J = 8.5, 7.1 Hz, 1H), 7.63 (dd, J = 7.1, 1.2 Hz, 1H), 7.49
(dd, J = 8.6, 4.2 Hz, 1H). 13C NMR (126 MHz, MeOD/CDCl3) δ
162.26, 149.88, 148.16, 147.70, 145.15, 138.92, 138.09, 136.41,
134.74, 129.44, 128.38, 128.03, 127.58, 127.37, 126.44, 122.70,
121.56. HRMS (ESI) m/z calc C17H12N3O [M + H]+ 274.0975;
found = 274.0984.
6-(Pyrazolo[1,5-a]pyridin-3-yl)quinazolin-4(3H)-one, 9. (4-
Oxo-3,4-dihydroquinazolin-6-yl)boronic acid (30 mg; 0.158 mmol;
1.0 equiv), 3-bromopyrazolo[1,5-a]pyridine (31 mg; 0.158 mmol; 1.0
equiv), K2CO3 (66 mg; 4.74 mmol; 3.0 equiv), bis(di-tert-butyl(4-
dimethylaminophenyl)phosphine)dichloropalladium(II) (5.6 mg;
0.00790 mmol; 5 mol %), DME (1 mL; 0.079 M), and water (1
mL; 0.079 M) were charged to a microwave vial. The vial was sealed
and purged of air with five rounds of vacuum and N2. The mixture
was stirred at 150 °C for 1 h under microwave irradiation. The
reaction mixture was cooled to <40 °C and diluted with CH2Cl2 (50
mL) and passed through a syringe filter, and solvent was removed
under a vacuum. The residue was purified initially by column
chromatography using a solvent system of 0−8% MeOH in CH2Cl2,
followed by purification by preparative HPLC (see Supporting
Information for details). 6-(Pyrazolo[1,5-a]pyridin-3-yl)quinazolin-
4(3H)-one (14 mg; 0.0537 mmol; 34%) was isolated as a white solid.
1H NMR (500 MHz, MeOD) δ 8.53 (dt, J = 7.0, 1.1 Hz, 1H), 8.47
(d, J = 2.2 Hz, 1H), 8.25 (s, 1H), 8.07 (dd, J = 8.4, 2.2 Hz, 1H), 8.01
(s, 1H), 7.99 (dt, J = 9.1, 1.2 Hz, 1H), 7.79 (d, J = 8.5 Hz, 1H), 7.34
(ddd, J = 9.0, 6.7, 1.1 Hz, 1H), 6.94 (td, J = 6.9, 1.3 Hz, 1H). 13C
NMR (126 MHz, MeOD) δ 161.94, 146.63, 144.09, 140.21, 137.18,
133.48, 132.45, 128.82, 127.64, 125.37, 123.09, 123.04, 117.31,
113.02, 111.42. HRMS (ESI) m/z calc C15H11N4O [M + H]+
263.0927; found = 263.0929.
2-Methyl-6-(quinolin-4-yl)quinazolin-4(3H)-one, 14. Follow-
ing general procedure 2, quinolin-4-ylboronic acid (25 mg; 0.144
mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721 mmol; 0.05 equiv),
6-bromo-2-methylquinazolin-4(3H)-one (34 mg; 0.144 mmol; 1.0
5-Methyl-6-(quinolin-4-yl)quinazolin-4(3H)-one, 10. Follow-
ing general procedure 2, quinolin-4-ylboronic acid (22 mg; 0.126
I
DOI: 10.1021/acs.jmedchem.8b00782
J. Med. Chem. XXXX, XXX, XXX−XXX

Journal of Medicinal Chemistry
Article
equiv), [0.5 M] Na2CO3(aq) (288 μL; 0.144 mmol; 1.0 equiv), and
1,4-dioxane (2 mL; 0.072 M) were used to yield 2-methyl-6-
(quinolin-4-yl)quinazolin-4(3H)-one (29 mg; 0.101 mmol; 70%) as a
white solid. Reaction temperature: 130 °C. Purification: 0−8%
dioxane (2 mL; 0.072 M) were used to yield 3-cyclohexyl-6-(quinolin-
4-yl)quinazolin-4(3H)-one (42 mg; 0.118 mmol; 82%) as a pale
yellow glass. Reaction temperature: 130 °C. Purification: 0−8%
1
MeOH in CH2Cl2. H NMR (500 MHz, CDCl3) δ 8.97 (d, J = 4.4
1
MeOH in CH2Cl2. H NMR (500 MHz, MeOD) δ 8.90 (d, J = 4.5
Hz, 1H), 8.48 (dd, J = 2.0, 0.6 Hz, 1H), 8.22 (s, 1H), 7.90 (dd, J =
8.3, 2.0 Hz, 1H), 7.87 (d, J = 8.1 Hz, 1H), 7.77 (ddd, J = 8.4, 6.8, 1.4
Hz, 1H), 7.66 (ddd, J = 12.0, 8.3, 1.4 Hz, 1H), 7.54 (ddd, J = 8.2, 6.8,
1.3 Hz, 1H), 7.47 (td, J = 7.6, 3.0 Hz, 1H), 7.41 (d, J = 4.4 Hz, 1H),
4.85 (tt, J = 12.3, 3.7 Hz, 1H), 2.09−2.02 (m, 2H), 1.97 (dt, J = 13.8,
3.6 Hz, 2H), 1.82 (d, J = 13.5 Hz, 1H), 1.69 (qd, J = 12.4, 3.4 Hz,
2H), 1.55 (qt, J = 13.1, 3.4 Hz, 2H), 1.34−1.24 (m, 1H). 13C NMR
(126 MHz, CDCl3) δ 160.55, 149.83, 149.75, 148.51, 147.41, 144.68,
136.87, 135.35, 132.02, 129.76, 128.59, 127.87, 127.60, 127.13,
126.47, 122.08, 121.58, 53.67, 32.63, 25.88, 25.24. HRMS (ESI) m/z
calc C23H22N3O [M + H]+ 356.1758; found = 356.1768.
Hz, 1H), 8.36 (d, J = 2.1 Hz, 1H), 8.14 (dt, J = 8.5, 1.0 Hz, 1H), 7.95
(dd, J = 8.4, 2.2 Hz, 1H), 7.93−7.91 (m, 1H), 7.83−7.78 (m, 2H),
7.59 (ddd, J = 8.3, 6.9, 1.2 Hz, 1H), 7.51 (d, J = 4.5 Hz, 1H), 2.53 (s,
3H). 13C NMR (126 MHz, MeOD) δ 162.60, 155.65, 149.36, 148.31,
147.93, 147.88, 135.76, 135.69, 129.94, 128.56, 127.29, 126.97,
126.52, 126.38, 125.41, 121.59, 120.73, 20.69. HRMS (ESI) m/z calc
C18H14N3O [M + H]+ 288.1132; found = 288.1133.
2-Methyl-6-(quinolin-5-yl)quinazolin-4(3H)-one, 15. Follow-
ing general procedure 2, quinolin-5-ylboronic acid (25 mg; 0.144
mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721 mmol; 0.05 equiv),
6-bromo-2-methylquinazolin-4(3H)-one (34 mg; 0.144 mmol; 1.0
equiv), [0.5 M] Na2CO3(aq) (288 μL; 0.144 mmol; 1.0 equiv), and
1,4-dioxane (2 mL; 0.072 M) were used to yield 2-methyl-6-
(quinolin-5-yl)quinazolin-4(3H)-one (24 mg; 0.0836 mmol; 58%) as
a white solid. Reaction temperature: 130 °C. Purification: 0−8%
MeOH in CH2Cl2. 1H NMR (500 MHz, MeOD) δ 8.86 (dd, J = 4.3,
1.7 Hz, 1H), 8.30 (d, J = 2.0 Hz, 1H), 8.27 (ddd, J = 8.6, 1.7, 0.9 Hz,
1H), 8.11 (dt, J = 8.5, 1.1 Hz, 1H), 7.86 (dd, J = 8.4, 2.1 Hz, 1H),
7.82 (dd, J = 8.5, 7.1 Hz, 1H), 7.76 (d, J = 8.4 Hz, 1H), 7.60 (dd, J =
7.1, 1.2 Hz, 1H), 7.46 (dd, J = 8.6, 4.3 Hz, 1H), 2.51 (s, 3H). 13C
NMR (126 MHz, MeOD) δ 162.79, 154.99, 149.84, 148.15, 147.72,
139.04, 137.35, 136.41, 134.78, 129.43, 128.28, 127.96, 127.22,
126.62, 126.43, 121.49, 120.65, 20.96. HRMS (ESI) m/z calc
C18H14N3O [M + H]+ 288.1132; found = 288.1144.
3-(4-Morpholinophenyl)-6-(quinolin-4-yl)quinazolin-4(3H)-
one, 16. Following general procedure 2, 6-bromo-3-(4-
morpholinophenyl)quinazolin-4(3H)-one (333 mg; 0.867 mmol; 1.0
equiv), quinolin-4-yl boronic acid (170 mg; 0.867 mmol; 1.0 equiv),
PdCl2(PPh3)2 (30 mg; 0.0433 mmol; 0.05 equiv), [0.5 M]
Na2CO3(aq) (1.73 mL; 0.867 mmol; 1.0 equiv) and 1,4-dioxane (10
mL; 0.087 M) were used to yield 3-(4-morpholinophenyl)-6-
(quinolin-4-yl)quinazolin-4(3H)-one (180 mg; 0.414 mmol; 48%)
as pale purple solid. Reaction temperature: 150 °C. Purification: 0−
8% MeOH in CH2Cl2. 1H NMR (500 MHz, CDCl3) δ 9.00 (d, J = 4.4
Hz, 1H), 8.54 (dd, J = 1.8, 0.9 Hz, 1H), 8.25−8.20 (m, 2H), 7.95−
7.94 (m, 2H), 7.92−7.89 (m, 1H), 7.78 (ddd, J = 8.3, 6.8, 1.4 Hz,
1H), 7.55 (ddd, J = 8.3, 6.8, 1.3 Hz, 1H), 7.43 (d, J = 4.4 Hz, 1H),
7.37−7.34 (m, 2H), 7.08−7.02 (m, 2H), 3.92−3.88 (m, 4H), 3.29−
3.23 (m, 4H). 13C NMR (126 MHz, CDCl3) δ 160.95, 151.67,
149.96, 148.70, 147.91, 147.22, 146.86, 137.35, 136.15, 135.63,
130.04, 129.59, 128.03, 127.95, 127.67, 127.10, 125.37, 122.62,
121.57, 115.91, 115.87, 66.73, 48.74. HRMS (ESI) m/z calc
C27H23N4O2 [M + H]+ 435.1816; found = 435.1814.
3-(3-Morpholinopropyl)-6-(quinolin-4-yl)quinazolin-4(3H)-
one, 19. Following general procedure 2, quinolin-4-ylboronic acid
(25 mg; 0.144 mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721
mmol; 0.05 equiv), 6-bromo-3-(3-morpholinopropyl)quinazolin-
4(3H)-one (51 mg; 0.144 mmol; 1.0 equiv), [0.5 M] Na2CO3(aq)
(288 μL; 0.144 mmol; 1.0 equiv) and 1,4-dioxane (2 mL; 0.072 M)
were used to yield 3-(3-morpholinopropyl)-6-(quinolin-4-yl)-
quinazolin-4(3H)-one (21 mg; 0.0525 mmol; 36%) as a pale yellow
glass. Reaction temperature: 130 °C. Purification: 0−8% MeOH in
1
CH2Cl2. H NMR (500 MHz, CDCl3) δ 8.93 (d, J = 4.4 Hz, 1H),
8.44 (d, J = 2.0 Hz, 1H), 8.22 (s, 1H), 8.18 (dd, J = 8.6, 1.2 Hz, 1H),
7.90 (dd, J = 8.4, 2.0 Hz, 1H), 7.88−7.84 (m, 2H), 7.76 (ddd, J = 8.4,
6.8, 1.4 Hz, 1H), 7.53 (ddd, J = 8.4, 6.9, 1.3 Hz, 1H), 7.40 (d, J = 4.4
Hz, 1H), 4.12 (t, J = 6.7 Hz, 2H), 3.68 (t, J = 4.6 Hz, 4H), 2.42 (q, J =
6.4 Hz, 6H), 2.02 (p, J = 6.7 Hz, 2H). 13C NMR (126 MHz, CDCl3)
δ 161.04, 149.65, 148.28, 147.93, 147.90, 147.25, 136.97, 135.48,
129.82, 129.48, 127.65, 127.46, 127.24, 126.43, 125.36, 122.21,
121.59, 66.85, 54.91, 53.34, 45.39, 24.85. HRMS (ESI) m/z calc
C24H25N4O2 [M + H]+ 401.1972; found = 401.1984.
3-(4-(Dimethylamino)phenyl)-6-(quinolin-4-yl)quinazolin-
4(3H)-one, 20. Following general procedure 2, quinolin-4-ylboronic
acid (25 mg; 0.144 mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721
mmol; 0.05 equiv), 6-bromo-3-(4-(dimethylamino)phenyl)-
quinazolin-4(3H)-one (49 mg; 0.144 mmol; 1.0 equiv), [0.5 M]
Na2CO3(aq) (288 μL; 0.144 mmol; 1.0 equiv), and 1,4-dioxane (2 mL;
0.072 M) were used to yield 3-(4-(dimethylamino)phenyl)-6-
(quinolin-4-yl)quinazolin-4(3H)-one (45 mg; 0.115 mmol; 80%) as
a white solid. Reaction temperature: 130 °C. Purification: 0−8%
1
MeOH in CH2Cl2. H NMR (500 MHz, CDCl3) δ 9.00 (d, J = 4.4
Hz, 1H), 8.54 (dd, J = 1.6, 1.0 Hz, 1H), 8.23−8.20 (m, 2H), 7.93−
7.92 (m, 2H), 7.91 (ddd, J = 8.5, 1.4, 0.6 Hz, 1H), 7.76 (ddd, J = 8.4,
6.8, 1.4 Hz, 1H), 7.54 (ddd, J = 8.3, 6.9, 1.3 Hz, 1H), 7.42 (d, J = 4.4
Hz, 1H), 7.29 (dd, J = 8.8, 2.0 Hz, 2H), 6.85−6.80 (m, 2H), 3.03 (s,
6H). 13C NMR (126 MHz, CDCl3) δ 161.11, 150.73, 149.98, 148.71,
147.98, 147.65, 146.91, 137.15, 135.47, 130.03, 129.55, 128.03,
127.88, 127.48, 127.06, 126.44, 125.78, 125.42, 122.69, 121.58,
112.50, 40.47. HRMS (ESI) m/z calc C25H21N4O [M + H]+
393.1710; found = 393.1712.
3-Phenyl-6-(quinolin-4-yl)quinazolin-4(3H)-one, 17. Follow-
ing general procedure 2, quinolin-4-ylboronic acid (25 mg; 0.144
mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721 mmol; 0.05 equiv),
6-bromo-3-phenylquinazolin-4(3H)-one (42 mg; 0.144 mmol; 1.0
equiv), [0.5 M] Na2CO3(aq) (288 μL; 0.144 mmol; 1.0 equiv), and
1,4-dioxane (2 mL; 0.072 M) were used to yield 3-phenyl-6-
(quinolin-4-yl)quinazolin-4(3H)-one (37 mg; 0.106 mmol; 74%) as a
white solid. Reaction temperature: 130 °C. Purification: 0−8%
2,5-Dimethyl-6-(quinolin-4-yl)quinazolin-4(3H)-one, 21. Fol-
lowing general procedure 2, quinolin-4-ylboronic acid (25 mg; 0.144
mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721 mmol; 0.05 equiv),
6-bromo-2,5-dimethylquinazolin-4(3H)-one (36 mg; 0.144 mmol; 1.0
equiv), [0.5 M] Na2CO3(aq) (288 μL; 0.144 mmol; 1.0 equiv), and
1,4-dioxane (2 mL; 0.072 M) were used to yield 2,5-dimethyl-6-
(quinolin-4-yl)quinazolin-4(3H)-one (23 mg; 0.0764 mmol; 53%) as
a white solid. Reaction temperature: 130 °C. Purification: 0−8%
1
MeOH in CH2Cl2. H NMR (500 MHz, CDCl3) δ 8.98 (d, J = 4.4
Hz, 1H), 8.54 (dd, J = 1.8, 0.9 Hz, 1H), 8.23 (s, 1H), 8.21 (dt, J = 8.6,
0.8 Hz, 1H), 7.96−7.95 (m, 2H), 7.90 (dd, J = 8.5, 1.4 Hz, 1H), 7.77
(ddd, J = 8.4, 6.9, 1.5 Hz, 1H), 7.63−7.50 (m, 4H), 7.48−7.45 (m,
2H), 7.43 (d, J = 4.4 Hz, 1H). 13C NMR (126 MHz, CDCl3) δ
160.63, 149.82, 149.73, 148.50, 147.80, 146.83, 137.47, 137.24,
135.81, 129.77, 129.77, 129.74, 129.37, 128.04, 127.97, 127.21,
126.96, 126.42, 125.34, 122.57, 121.59. HRMS (ESI) m/z calc
C23H16N3O [M + H]+ 350.1288; found = 350.1303.
3-Cyclohexyl-6-(quinolin-4-yl)quinazolin-4(3H)-one, 18. Fol-
lowing general procedure 2, quinolin-4-ylboronic acid (25 mg; 0.144
mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721 mmol; 0.05 equiv),
6-bromo-3-cyclohexylquinazolin-4(3H)-one (44 mg; 0.144 mmol; 1.0
equiv), [0.5 M] Na2CO3(aq) (288 μL; 0.144 mmol; 1.0 equiv) and 1,4-
1
MeOH in CH2Cl2. H NMR (500 MHz, MeOD) δ 8.89 (d, J = 4.4
Hz, 1H), 8.12 (dt, J = 8.4, 0.9 Hz, 1H), 7.75 (ddd, J = 8.4, 6.7, 1.5 Hz,
1H), 7.56 (d, J = 8.4 Hz, 1H), 7.52 (d, J = 8.4 Hz, 1H), 7.48 (ddd, J =
8.1, 6.7, 1.2 Hz, 1H), 7.44−7.41 (m, 1H), 7.33 (d, J = 4.4 Hz, 1H),
2.51 (s, 3H), 2.46 (s, 3H). 13C NMR (126 MHz, MeOD) δ 163.54,
154.82, 150.45, 149.45, 148.80, 147.55, 139.02, 136.03, 135.27,
130.05, 128.75, 127.39, 127.26, 125.78, 124.12, 121.97, 119.44, 20.65,
19.48. HRMS (ESI) m/z calc C19H16N3O [M + H]+ 302.1288; found
= 302.1282.
J
DOI: 10.1021/acs.jmedchem.8b00782
J. Med. Chem. XXXX, XXX, XXX−XXX

Journal of Medicinal Chemistry
Article
2-Ethyl-5-methyl-6-(quinolin-4-yl)quinazolin-4(3H)-one, 22.
Following general procedure 2, quinolin-4-ylboronic acid (25 mg;
0.144 mmol; 1.0 equiv), PdCl2(PPh3)2 (5.1 mg; 0.00721 mmol; 0.05
equiv), 6-bromo-2-ethyl-5-methylquinazolin-4(3H)-one (38 mg;
0.144 mmol; 1.0 equiv), [0.5 M] Na2CO3(aq) (288 μL; 0.144 mmol;
1.0 equiv), and 1,4-dioxane (2 mL; 0.072 M) were used to yield 2-
ethyl-5-methyl-6-(quinolin-4-yl)quinazolin-4(3H)-one (28 mg;
0.0889 mmol; 62%) as a white solid. Reaction temperature: 130
°C. Purification: 0−8% MeOH in CH2Cl2. 1H NMR (500 MHz,
CDCl3) δ 11.93 (s, 1H), 9.04 (d, J = 4.3 Hz, 1H), 8.24 (dt, J = 8.6, 0.9
Hz, 1H), 7.77 (ddd, J = 8.4, 6.0, 2.2 Hz, 1H), 7.69 (dd, J = 8.3, 0.7
Hz, 1H), 7.59 (d, J = 8.3 Hz, 1H), 7.53−7.47 (m, 2H), 7.34 (d, J =
4.3 Hz, 1H), 2.83 (q, J = 7.6 Hz, 2H), 2.63 (s, 3H), 1.46 (t, J = 7.6
Hz, 3H). 13C NMR (126 MHz, CDCl3) δ 165.23, 158.07, 151.32,
150.00, 148.29, 148.05, 139.05, 136.32, 135.55, 129.88, 129.67,
127.36, 126.99, 125.78, 125.26, 121.92, 119.41, 28.83, 19.77, 11.49.
HRMS (ESI) m/z calc C20H18N3O [M + H]+ 316.1445; found =
316.1449.
2-Benzyl-5-methyl-6-(quinolin-4-yl)quinazolin-4(3H)-one,
23. Following general procedure 2, quinolin-4-ylboronic acid (12 mg;
0.0692 mmol; 1.0 equiv), PdCl2(PPh3)2 (5 mg; 0.00712 mmol; 0.1
equiv), 2-benzyl-6-bromo-5-methylquinazolin-4(3H)-one (23 mg;
0.0692 mmol; 1.0 equiv), [0.5 M] Na2CO3(aq) (138 μL; 0.0692
mmol; 1.0 equiv), and 1,4-dioxane (2 mL; 0.035 M) were used to
yield 2-benzyl-5-methyl-6-(quinolin-4-yl)quinazolin-4(3H)-one (17
mg; 0.0451 mmol; 65%) as a white solid. Reaction temperature:
150 °C. Purification: 0−8% MeOH in CH2Cl2. 1H NMR (500 MHz,
DMSO) δ 12.39 (s, 1H), 9.00 (d, J = 4.3 Hz, 1H), 8.13 (d, J = 8.4 Hz,
1H), 7.80 (ddd, J = 8.4, 6.8, 1.4 Hz, 1H), 7.58 (d, J = 0.7 Hz, 2H),
7.56−7.52 (m, 1H), 7.44−7.41 (m, 3H, 14), 7.39 (ddd, J = 8.5, 1.6,
0.7 Hz, 1H), 7.38−7.34 (m, 2H), 7.30−7.25 (m, 1H), 3.96 (s, 2H),
2.43 (s, 3H). 13C NMR (126 MHz, DMSO) δ 163.35, 156.81, 151.13,
150.75, 148.24, 147.58, 138.26, 137.06, 135.87, 135.32, 130.10,
130.00, 129.32, 128.99, 127.84, 127.29, 127.10, 125.95, 125.49,
122.53, 119.88, 40.31, 19.80. HRMS (ESI) m/z calc C25H20N3O [M
+ H]+ 378.1601; found = 378.1608.
3,8-Dimethyl-7-(quinolin-4-yl)isoquinolin-1(2H)-one, 24.
Following general procedure 2, quinolin-4-ylboronic acid (38 mg;
0.218 mmol; 1.1 equiv), PdCl2(PPh3)2 (7.0 mg; 0.0100 mmol; 0.05
equiv), 7-bromo-3,8-dimethyl-2H-isoquinolin-1-one (50 mg; 0.198
mmol; 1.0 equiv), [0.5 M] Na2CO3(aq) (397 μL; 0.198 mmol; 1.0
equiv), and 1,4-dioxane (2 mL; 0.099 M) were used to yield 3,8-
dimethyl-7-(quinolin-4-yl)isoquinolin-1(2H)-one (36 mg; 0.120
mmol; 61% yield) as a white solid. Reaction temperature: 150 °C.
Purification: 0−8% MeOH in CH2Cl2. 1H NMR (500 MHz, CDCl3)
δ 10.48 (s, 1H), 9.01 (d, J = 4.3 Hz, 1H), 8.21 (dt, J = 8.4, 0.9 Hz,
1H), 7.75 (ddd, J = 8.4, 6.3, 1.9 Hz, 1H), 7.53−7.45 (m, 2H), 7.41−
7.40 (m, 2H), 7.32 (d, J = 4.3 Hz, 1H), 6.32 (d, J = 1.3 Hz, 1H), 2.65
(s, 3H), 2.37 (d, J = 1.1 Hz, 3H). 13C NMR (126 MHz, CDCl3) δ
165.32, 150.08, 148.72, 148.37, 140.67, 139.68, 138.01, 135.92,
133.52, 129.84, 129.50, 127.52, 126.79, 126.00, 123.58, 122.87,
121.94, 104.89, 20.03, 18.89. HRMS (ESI) m/z calc C20H17N2O [M
+ H]+ 301.1335, found = 301.1328.
2-Benzyl-6-bromo-5-methylquinazolin-4(3H)-one, 26. 2-
Phenylacetonitrile (500 mg; 4.27 mmol; 1.0 equiv) and hydroxyl-
amine [50% in water] (424 μL; 6.41 mmol; 1.5 equiv) were stirred at
120 °C for 2 h. The mixture was cooled to <40 °C, and 6-amino-3-
bromo-2-methylbenzoic acid (985 mg; 4.27 mmol; 1.0 equiv) was
added. The mixture was heated to 150 °C, stirred for 2 h, and cooled
to <40 °C. EtOH (20 mL) was added to the reaction mixture which
induced precipitation. The solvent was decanted three times from
EtOH, and the solid residue was dried under high vacuum. 2-Benzyl-
6-bromo-5-methylquinazolin-4(3H)-one (341 mg; 1.04 mmol; 24%)
was isolated at a white solid. 1H NMR (500 MHz, DMSO) δ 12.15 (s,
1H), 7.91 (d, J = 8.7 Hz, 1H), 7.38−7.34 (m, 3H), 7.34−7.30 (m,
2H), 7.26−7.22 (m, 1H), 3.89 (s, 2H), 2.90 (s, 3H). 13C NMR (126
MHz, DMSO) δ 157.94, 156.89, 150.36, 138.88, 137.89, 136.83,
129.32, 128.96, 127.27, 127.14, 122.99, 121.14, 40.81, 21.54. HRMS
(ESI) m/z calc C16H14BrN2O [M + H]+ 329.0284; found = 329.0284.
3-(4-Bromo-3-methylphenyl)-2-methylacrylic acid, 27. A
mixture of 4-bromo-3-methylbenzaldehyde (4.98 g, 25 mmol),
methylmalonic acid (5.90 g, 50 mmol), and piperidine (4.94 mL,
50 mmol) in pyridine (30 mL) was heated at reflux for 24 h. The
mixture was cooled and added to a mixture of ice (ca. 125 g) and
conc. HCl (70 mL). The precipitate formed was filtered off and
washed with cold water. The product was dried under vacuum to
afford 3-(4-bromo-3-methylphenyl)-2-methylacrylic acid (6.1 g,
1
64.3% yield) as a waxy solid. H NMR (500 MHz, CDCl3) δ 11.77
(s, 1H), 7.74 (d, J = 1.6 Hz, 1H), 7.58 (d, J = 8.2 Hz, 1H), 7.30 (d, J =
2.1 Hz, 1H), 7.14 (dd, J = 8.3, 2.2 Hz, 1H), 2.45 (s, 3H), 2.14 (d, J =
1.6 Hz, 3H). 13C NMR (126 MHz, CDCl3) δ 173.72, 139.99, 138.10,
134.72, 132.44, 132.11, 128.49, 127.94, 125.48, 22.98, 13.79.
3-(4-Bromo-3-methylphenyl)-2-methylacryloyl azide, 28.
To a suspension of 3-(4-bromo-3-methylphenyl)-2-methylacrylic
acid (4.80 ;, 18.8 mmol; 1.0 equiv) in acetone (100 mL) at 0 °C
was added triethylamine (3.41 mL; 24.5 mmol; 1.3 equiv). A clear
solution was formed. Then, ethyl chloroformate (2.16 mL; 22.6
mmol; 1.2 equiv) was added, and a thick suspension was formed. The
suspension was allowed to warm to room temperature. After 2 h,
sodium azide (1.83 g; 28.2 mmol; 1.5 equiv) in water (15 mL) was
added dropwise, and the suspension was stirred for a further 2 h. The
suspension was cooled down and diluted with water (50 mL). Ethyl
acetate (200 mL) was added, the layers were separated, and the
aqueous layer was extracted with more ethyl acetate (2 × 50 mL).
The organic were washed with sat. aq. NaHCO3 (2 × 50 mL), dried
(MgSO4), filtered and concentrated (without heating) to yield the
1
product as a white solid (5.1 g, 97% yield). H NMR (500 MHz,
CDCl3) δ 7.65 (d, J = 1.5 Hz, 1H), 7.58 (d, J = 8.3 Hz, 1H), 7.29−
7.28 (m, 1H), 7.12 (dd, J = 8.3, 2.3 Hz, 1H), 2.44 (s, 3H), 2.12 (d, J =
1.4 Hz, 3H). 13C NMR (126 MHz, CDCl3) δ 174.36, 139.94, 138.23,
134.36, 132.54, 132.22, 129.99, 128.59, 125.92, 22.98, 13.87.
7-Bromo-3,8-dimethyl-2H-isoquinolin-1-one, 29 and 7-
bromo-3,6-dimethyl-2H-isoquinolin-1-one, 30. A suspension of
3-(4-bromo-3-methylphenyl)-2-methylacryloyl azide (4.76 g; 17.0
mmol; 1.0 equiv) in 1,2-dichlorobenzene (70 mL) was heated to 140
°C for 1 h. Then, iodine (431.5 mg; 1.7 mmol; 0.1 equiv) was added,
and the mixture was heated at reflux (ca. 180 °C) for 6 h and cooled
to room temperature. The solution was stirred overnight at room
temperature, and the solid formed was filtered and washed with 20
mL of cyclohexane. The solid was dried for 1 h at 50 °C and 20 Torr
to give a mixture of 29 and 30 (2.16 g; 50% yield) in a ratio 3:2 (1H
NMR). Normal phase flash chromatography of the mixture (0−25%
EtOAc in cyclohexane) gave 116 mg of pure 29, 660 mg of mixture
and 260 mg of pure 30. For 29: 1H NMR (500 MHz, DMSO) δ 11.24
(s, 1H), 7.77 (d, J = 8.5 Hz, 1H), 7.29 (d, J = 8.5 Hz, 1H), 6.27 (dd, J
= 2.0, 1.1 Hz, 1H), 2.95 (s, 3H), 2.16 (d, J = 1.1 Hz, 3H). 13C NMR
(126 MHz, DMSO) δ 163.21, 140.03, 139.80, 139.40, 136.12, 125.89,
124.19, 123.08, 103.48, 21.76, 18.77. HRMS (ESI) m/z calc for
C11H1179BrNO [M + H]+ 252.0019, found = 252.0014. For 30: H
1
NMR (DMSO, 500 MHz) δ 11.30 (br-s, 1H), 8.20 (s, 1H), 7.51 (a,
1H), 6.26 (s, 1H), 2.43 (s, 3H), 2.18 (s, 3H). 13C NMR (DMSO, 126
MHz) δ 161.2, 141.8, 139.5, 137.6, 129.6, 127.4, 123.8, 121.1, 102.0,
22.8, 18.8. HRMS (ESI) m/z calc for C11H1179BrNO [M + H]+
252.0019, found = 252.0015.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.jmed-
chem.8b00782.
■
S
Molecular formula strings (CSV)
Experimental and characterization details for all new
compounds, assay data, crystallographic data and NMR
spectra (PDF)
Accession Codes
The PDB ID codes for 11, 16, and 21 bound to ALK2 are
6GI6, 6GIN and 6GIP, respectively. Authors will release the
K
DOI: 10.1021/acs.jmedchem.8b00782
J. Med. Chem. XXXX, XXX, XXX−XXX

Journal of Medicinal Chemistry
Article
(6) Yu, P. B.; Hong, C. C.; Sachidanandan, C.; Babitt, J. L.; Deng, D.
Y.; Hoyng, S. a; Lin, H. Y.; Bloch, K. D.; Peterson, R. T.
Dorsomorphin inhibits BMP signals required for embryogenesis and
iron metabolism. Nat. Chem. Biol. 2008, 4 (1), 33−41.
(7) Cuny, G. D.; Yu, P. B.; Laha, J. K.; Xing, X.; Liu, J.-F.; Lai, C. S.;
Deng, D. Y.; Sachidanandan, C.; Bloch, K. D.; Peterson, R. T.
Structure-activity relationship study of bone morphogenetic protein
(BMP) signaling inhibitors. Bioorg. Med. Chem. Lett. 2008, 18 (15),
4388−4392.
atomic coordinates and experimental data upon article
publication.
AUTHOR INFORMATION
Corresponding Author
*E-mail: Swen.Hoelder@icr.ac.uk. Phone: +44 (0)
2087224353.
■
ORCID
(8) Mohedas, A. H.; Xing, X.; Armstrong, K. a.; Bullock, A. N.;
Cuny, G. D.; Yu, P. B. Development of an ALK2-biased BMP type I
receptor kinase inhibitor. ACS Chem. Biol. 2013, 8 (6), 1291−1302.
(9) Engers, D. W.; Frist, A. Y.; Lindsley, C. W.; Hong, C. C.;
Hopkins, C. R. Synthesis and structure-activity relationships of a novel
and selective bone morphogenetic protein receptor (BMP) inhibitor
derived from the pyrazolo[1.5-a]pyrimidine scaffold of dorsomorphin:
the discovery of ML347 as an ALK2 versus ALK3 selective MLPCN
probe. Bioorg. Med. Chem. Lett. 2013, 23 (11), 3248−3252.
(10) (i) Vogt, J.; Traynor, R.; Sapkota, G. P. The specificities of
small molecule inhibitors of the TGFß and BMP pathways. Cell.
Signalling 2011, 23 (11), 1831−1842. (ii) Sinha, S.; Mundy, C.;
Bechtold, T.; Sgariglia, F.; Ibrahim, M. M.; Billings, P. C.; Carroll, K.;
Koyama, E.; Jones, K. B.; Pacifici, M. Unsuspected osteochondroma-
like outgrowths in the cranial base of Hereditary Multiple Exostoses
patients and modeling and treatment with a BMP antagonist in mice.
PLoS Genet. 2017, 13 (4), e1006742.
(11) Sanvitale, C. E.; Kerr, G.; Chaikuad, A.; Ramel, M.-C.;
Mohedas, A. H.; Reichert, S.; Wang, Y.; Triffitt, J. T.; Cuny, G. D.; Yu,
P. B.; Hill, C. S.; Bullock, A. N. A new class of small molecule
inhibitor of BMP signaling. PLoS One 2013, 8 (4), e62721.
(12) Mohedas, A.; Wang, Y.; Sanvitale, C. E.; Canning, P.; Choi, S.;
Xing, X.; Bullock, A. N.; Cuny, G. D.; Yu, P. B. Structure−activity
relationship of 3,5-diaryl-2-aminopyridine ALK2 inhibitors reveals
unaltered binding affinity for fibrodysplasia ossificans progressiva
causing mutants. J. Med. Chem. 2014, 57, 7900−7915.
(13) Boys, M. L.; Bian, F.; Kramer, J. B.; Chio, C. L.; Ren, X. D.;
Chen, H.; Barrett, S. D.; Sexton, K. E.; Iula, D. M.; Filzen, G. F.;
Nguyen, M. N.; Angell, P.; Downs, V. L.; Wang, Z.; Raheja, N.;
Ellsworth, E. L.; Fakhoury, S.; Bratton, L. D.; Keller, P. R.; Gowan, R.;
Drummond, E. M.; Maiti, S. N.; Hena, M. a.; Lu, L.; McConnell, P.;
Knafels, J. D.; Thanabal, V.; Sun, F.; Alessi, D.; McCarthy, A.; Zhang,
E.; Finzel, B. C.; Patel, S.; Ciotti, S. M.; Eisma, R.; Payne, N. a.;
Gilbertsen, R. B.; Kostlan, C. R.; Pocalyko, D. J.; Lala, D. S. Discovery
of a series of 2-(1H-pyrazol-1-yl)pyridines as ALK5 inhibitors with
potential utility in the prevention of dermal scarring. Bioorg. Med.
Chem. Lett. 2012, 22 (10), 3392−3397.
́
Santiago Vazquez: 0000-0002-9296-6026
Swen Hoelder: 0000-0001-8636-1488
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
L.H. and J.M. were funded by Wellcome Trust [Grant Number
090171/Z/09/Z]. We acknowledge NHS funding to the
NIHR Biomedical Research Centre and funding from Cancer
Research UK [Grant Number C309/A11566]. S.V. thanks the
́
Spanish Ministerio de Educacion, Cultura y Deporte for a
“Salvador de Madariaga” mobility grant. C.J. and D.C.
acknowledge support from Children with Cancer UK, Abbie’s
Army and the DIPG Collaborative, the Lyla Nsouli Foundation
and Lucas’ Legacy. The authors thank Diamond Light Source
for beamtime (proposal mx10619), as well as the staff of
beamlines I02, I03, and I04 for assistance with crystal testing
and data collection. The SGC is a registered charity (Number
1097737) that receives funds from AbbVie, Bayer Pharma AG,
Boehringer Ingelheim, Canada Foundation for Innovation,
Eshelman Institute for Innovation, Genome Canada, Innova-
tive Medicines Initiative (EU/EFPIA) [ULTRA-DD Grant
No. 115766], Janssen, MSD, Merck KGaA., Novartis Pharma
AG, Ontario Ministry of Economic Development and
Innovation, Pfizer, Sao Paulo Research Foundation-FAPESP,
̃
Takeda, and Wellcome Trust [106169/ZZ14/Z].
ABBREVIATIONS USED
■
ALK, activin receptor-like kinase; DIPG, diffuse intrinsic
pontine glioma; FKBP12, FK506 binding protein 12; SMAD,
small mothers against decapantaplegic; FOP, fibrodysplasia
ossificans progressiva; RAF, rapidly accelerated fibrosarcoma;
PDGFR, platelet-derived growth factor receptor; BMP, bone
morphogenic protein; ID1, inhibitor of DNA binding 1
(14) Gellibert, F.; Woolven, J.; Fouchet, M.-H.; Mathews, N.;
Goodland, H.; Lovegrove, V.; Laroze, A.; Nguyen, V.-L.; Sautet, S.;
Wang, R.; Janson, C.; Smith, W.; Krysa, G.; Boullay, V.; De Gouville,
A.-C.; Huet, S.; Hartley, D. Identification of 1,5-naphthyridine
derivatives as a novel series of potent and selective TGF-β type I
receptor inhibitors. J. Med. Chem. 2004, 47, 4494−4506.
REFERENCES
■
(1) Vogt, J.; Traynor, R.; Sapkota, G. P. The specificities of small
molecule inhibitors of the TGFß and BMP pathways. Cell. Signalling
2011, 23 (11), 1831−1842.
(2) Chaikuad, A.; Alfano, I.; Kerr, G.; Sanvitale, C. E.; Boergermann,
J. H.; Triffitt, J. T.; Von Delft, F.; Knapp, S.; Knaus, P.; Bullock, A. N.
Structure of the bone morphogenetic protein receptor ALK2 and
implications for fibrodysplasia ossificans progressiva. J. Biol. Chem.
2012, 287 (44), 36990−36998.
(3) Hatsell, S. J.; Idone, V.; Wolken, D. M. A.; Huang, L.; Kim, H. J.;
Wang, L.; Wen, X.; Nannuru, K. C.; Jimenez, J.; Xie, L.; Das, N.;
Makhoul, G.; Chernomorsky, R.; D’Ambrosio, D.; Corpina, R. A.;
Schoenherr, C. J.; Feeley, K.; Yu, P. B.; Yancopoulos, G. D.; Murphy,
A. J.; Economides, A. N. ACVR1R206H receptor mutation causes
fibrodysplasia ossificans progressiva by imparting responsiveness to
activin A. Sci. Transl. Med. 2015, 7 (303), 303ra137.
(15) Hitchcock, S. A.; Pennington, L. D. Structure−brain exposure
relationships. J. Med. Chem. 2006, 49 (26), 7559−7583.
́
(16) Larrivee, B.; Prahst, C.; Gordon, E.; del Toro, R.; Mathivet, T.;
Duarte, A.; Simons, M.; Eichmann, A. ALK1 signaling inhibits
angiogenesis by cooperating with the Notch pathway. Dev. Cell 2012,
22, 489−500.
(17) Adib, M.; Ansari, S.; Mohammadi, A.; Bijanzadeh, H. R. A
novel, one-pot, solvent-, and catalyst-free synthesis of 2-aryl/alkyl-4
(3H)-quinazolinones. Tetrahedron Lett. 2010, 51 (1), 30−32.
(18) Gensler, W. J.; Berman, E. Decarboxylative condensation. α-
alkylcinnamic acids from aromatic aldehydes and alkylmalonic acids. J.
Am. Chem. Soc. 1958, 80, 4949−4954.
(4) Taylor, K. R.; Vinci, M.; Bullock, A. N.; Jones, C. ACVR1
mutations in DIPG: lessons learned from FOP. Cancer Res. 2014, 74
(17), 4565−4570.
(5) Warren, K. E. Diffuse intrinsic pontine glioma: poised for
progress. Front. Oncol. 2012, 2 (December), 205.
L
DOI: 10.1021/acs.jmedchem.8b00782
J. Med. Chem. XXXX, XXX, XXX−XXX