Efficient solution-phase synthesis of 4,5,7-trisubstituted pyrrolo[3,2- d ]pyrimidines

Article abstract of DOI:10.1021/co300106f

We have developed an efficient and robust route to synthesize 4,5,7-trisubstituted pyrrolo[3,2-d]pyrimidines as potent kinase inhibitors. This solution-phase synthesis features a S_NAr substitution reaction, cross-coupling reaction, one-pot reduction/reductive amination and N-alkylation reaction. These reactions occur rapidly with high yields and have broad substrate scopes. A variety of groups can be selectively introduced into the N5 and C7 positions of 4,5,7-trisubstituted pyrrolopyrimidines at a late stage of the synthesis, thereby providing a highly efficient approach to explore the structure-activity relationships of pyrrolopyrimidine derivatives. Four synthetic analogs have been profiled against a panel of 48 kinases and a new and selective FLT3 inhibitor 9 is identified.

Full text of DOI:10.1021/co300106f

Research Article
pubs.acs.org/acscombsci
Efficient Solution-Phase Synthesis of 4,5,7-Trisubstituted
Pyrrolo[3,2‑d]pyrimidines
Weihe Zhang, Jing Liu, Michael A. Stashko, and Xiaodong Wang*
Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry,
UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599, United States
S
* Supporting Information
ABSTRACT: We have developed an efficient and robust route to synthesize 4,5,
7-trisubstituted pyrrolo[3,2-d]pyrimidines as potent kinase inhibitors. This solution-
phase synthesis features a SNAr substitution reaction, cross-coupling reaction, one-pot
reduction/reductive amination and N-alkylation reaction. These reactions occur
rapidly with high yields and have broad substrate scopes. A variety of groups can be
selectively introduced into the N5 and C7 positions of 4,5,7-trisubstituted pyr-
rolopyrimidines at a late stage of the synthesis, thereby providing a highly efficient approach to explore the structure−activity
relationships of pyrrolopyrimidine derivatives. Four synthetic analogs have been profiled against a panel of 48 kinases and a new and
selective FLT3 inhibitor 9 is identified.
KEYWORDS: pyrrolopyrimidine, SNAr displacement, coupling reaction, reductive amination, N-alkylation
Although these methods are useful, the yields are poor for some
cases.11b In addition, the substituents R1 and R2 on the pyr-
rolopyrimidine core have to be introduced prior to the ring
formation, which renders further modification of these sub-
stituents difficult. In contrast, approach B starts with a simple
pyrrolopyrimidine core and the substituents are introduced late
in the synthesis, enabling exploration of diverse analogues
possible at lower cost and in a timely fashion. However, to date
there has been no reported method for this approach. In our
efforts to employ pyrrolopyrimidines as selective kinase inhibi-
tors, an efficient and robust method has been developed to
synthesize 4,5,7-trisubstituted pyrrolo[3,2-d]pyrimidine ana-
logues through approach B.
INTRODUCTION
■
Pyrrolopyrimidines have been broadly used as synthetic phar-
macophores in drug discovery due to their structural similarity to
purines with numerous associated biological activities. Accord-
ingly, pyrrolopyrimidines have been exploited as inhibitors of
kinases (VEGFR,1 FGFR,2 HGF,3 Akt,4 MMP,5 JAK,6 Lck,7 etc.),
methylthioadenosine phosphorylase (MTAP),8 purine nucleo-
side phosphorylase (PNP),9 and HIV replication.10 In one of our
drug discovery programs, we are interested in 4,5,7-trisubstituted
pyrrolo[3,2-d]pyrimidines as potential kinase inhibitors. Con-
sequently, it is important to develop facile and efficient methods
to synthesize this family of molecules. Retrosynthetic analysis
suggests that 4,5,7-trisubstituted pyrrolo[3,2-d]pyrimidines can
be synthesized through two general approaches (Scheme 1).
RESULTS AND DISCUSSION
■
Scheme 1. Approaches for Synthesis of Pyrrolopyrimidine
Derivatives
Compound 1 (Scheme 2) was chosen as the key building block
for our synthesis for the following reasons. First, the chloride
on the C4 position could be potentially displaced by various
nuclophiles to introduce diversified R1 substituents. Second, the
NO2/NH2 group at the C7 position could be used as a handle for
introduction of N-containing R2 substituents. Third, the R3
group could be attached through N-alkylation at the N5 position.
The key building block 1 was synthesized by chlorination of
the known compound 7-nitro-3H-pyrrolo[3,2-d]pyrimidin-
4(5H)-one with neat phosphorus(V) oxychloride under reflux
(Scheme 2). For 2-halopyrimidines, the halogen atom could be
replaced smoothly by various nuclophiles.12 However, the addi-
tional pyrrole ring in pyrrolopyrimidine makes the replacement
reaction more difficult. With 2-(trimethylsilyl)ethoxymethyl
(SEM) protecting group at nitrogen of the pyrrole ring, SNAr
Received: September 10, 2012
Revised: November 19, 2012
Published: November 26, 2012
Approach A is focused on the construction of the pyrrole
ring using substituted pyrimidines as the starting materials.11
© 2012 American Chemical Society
10
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
Scheme 2. Synthesis of the Key Building block 1 and Its Transformations
displacement ofchlorideattheC4positionof2 with 4-phenylphenol
went smoothly at room temperature in high yield. The direct dis-
placement of chloride in the key building block 1 with phenols,
however, was challenging and only occurred after heating at 175 °C
for 50 min under microwave irradiation. Because direct displacement
of chloride in 1 would circumvent the need for protection and
deprotection steps, this reaction was further explored (Table 1).
In the presence of potassium carbonate, phenol (entry 1),
para-substituted phenols (entries 2 and 5), and meta-substituted
phenol (entry 3) underwent the SNAr substitution reactions
smoothly with 1 in good yields, while ortho-substituted phenol
(entry 4) gave poor yield possibly because of the steric hindrance.
The ester functional group did not tolerate the reaction condi-
tions (entry 6) and an aliphatic alcohol was not reactive under
these conditions. However, conversion to an alkoxide (entry 7)
completed the transformation at lower temperature (120 vs
175 °C) and in a shorter reaction time (20 min vs 50 min).
Amines including aniline (entries 8−10) were better nucleo-
philes and reacted under much milder reaction conditions
(conventional heating at 80 °C for overnight) with higher yields.
More importantly, a few cross-coupling reactions also worked
using 1 as a reactant which further diversified the available R1
substituents. Accordingly, the R1 substituents of 4 could be
introduced either from a boronic acid/ester via Suzuki-Miyaura
coupling conditions13 (entries 11−15) or from a zinc reagent via
the Negishi coupling reaction14 (entries 16 and 17). In general,
electron donating groups increase while electron withdrawing
groups decrease reactivity of boronic acid in a Suzuki−Miyaura
couping reaction. For example, (2-methoxyphenyl)boronic
acid (entry 12) provided product 4k with higher yield than
(3-fluorophenyl)boronic acid (para-methoxyl) (entry 13). In
addition, furan could be introduced to the R1 position (entry 14)
and boronic ester (entry 15) also worked under the same reac-
tion conditions. While Suzuki-Miyaura coupling reaction is
suitable to introduce aromatic groups at the R1 position, Negishi
coupling reaction works better when R1 is an alkyl group. As shown
in Table 1, decant yields were obtained when two different zinc
reagents were used (entries 16 and 17).
We were also able to introduce tertiary amines and amide
groups at the C7 position of pyrrolopyrimidines by stepwise
approaches as illustrated in Scheme 4. First, the nitro group in 4g
was reduced to the corresponding amine in 8. Next, alkylation or
acylation of 8 provided 9 and 10, respectively. Although there are
three NH groups in 8, the newly formed primary amine is more
reactive likely due to the low electron density and/or steric
hindrance on the other two basic nitrogen atoms. The yield for
the alkylated 9 was 81% while those for acylated 10 with various
acid chlorides were lower because of competing N-diacylation at
the same position.
Finally, R3 substituents at the N5 position of pyrrolopyr-
imidines were introduced by N-alkylation (Table 2). Primary
alkyl chlorides reacted with 7 at 150 °C for 15 min under micro-
wave irradiation to provide the desired N-alkylated products
(entries 1−3). For secondary chlorides (entry 4), a larger excess
of halide (3 equivalents) and longer reaction time (30 min) were
needed. Primary bromides (entries 5−8) also gave the desired
N-alkylation products under the same reaction conditions as
for primary chlorides. However, cyclohexyl bromide or iodide
(entry 9) did not provide any desired alkylation product, pre-
sumably due to the elimination reaction of the bromide/iodide.
The final products 11 were obtained by removal of the Boc group
under acidic conditions.
A selectivity issue arises for compounds with a NHR group
at the C4 position such as 4g and 4i (Table 1) in the final
N-alkylation reaction because the nitrogen at the C4 position of
the pyrimidine demonstrated reactivity similar to the pyrrole
nitrogen. Accordingly, the nitrogen at the C4 position had to be
protected early in the synthesis. For example, compound 4h
(Table 1) could serve as an intermediate for this purpose as the
nitrogen at the C4 position was protected by a benzyl (Bn)
group. N-alkylation reaction of 4h with trans-tert-butyl (4-(bro-
momethyl)cyclohexyl)carbamate proceeded smoothly in good
yield (Scheme 5). After the reduction of the nitro group in 12 and
N-acylation of 13, compound 14 was obtained. The Bn protect-
ing group in 12 survived under the reductive hydrogenation
conditions but could subsequently be removed under acidic
conditions with higher temperature. The BOC protecting group
was removed by trifluoroacetic acid (TFA) after the removal of the
Bn group in 14 to provide 15. Through this alternative route, the
pyrrole nitrogen could be selectively alkylated.
Next, we explored the introduction of R2 substituents at the C7
position of pyrrolo[3,2-d]pyrimidines. Since coupling reactions
had been successfully applied to introduce the C-substituents,
such as aryl, heteroaryl, vinyl, alkynyl and benzyl, at this position
in a similar system,15 our focus was mainly on the introduction of
the diversified N-substituents. The most efficient way to achieve
this goal was through a one-pot reduction of the nitro group and
in situ reductive amination with aldehydes under hydrogen
atmosphere in the presence of palladium on activated charcoal.
Using this one-pot protocol, 3 was converted to 5 in high yield
(Scheme 3). The NHEt group at the C7 position in 5 was pro-
tected as a tert-butyl carbamate (Boc) (6) to minimize the
potential interference with the next N-alkylation on the N5 posi-
tion. Subsequently, the SEM protecting group in 6 was selectively
removed by treatment with TBAF to provide 7.
We have also investigated the potential applications of the
synthetic analogs as kinase inhibitors. Four structurally different
compounds 9, 10b, 11a, 15 were selected for the initial study.
Each of the four compounds was tested for its capacity to inhibit a
panel of 48 kinases using the Profiler Pro Kit (Caliper Life Sciences)
at a concentration of 10 μM. All the experiments were carried out in
duplicate. To our delight, the fms-like receptor tyrosine kinase-3
(FLT3) was the only kinase that was inhibited by more
than 50% and only by 9 (details in Supporting Information).
FLT3 is a validated target for drug discovery for a variety of
diseases.16 We thus further tested the inhibitory activity of 9 in
a concentration-dependent manner. The inhibition of FLT3
11
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
kinase activity was measured at the ATP Km using a microfluidic
capillary electrophoresis (MCE) assay,17 in which phosphorylated and
unphosphorylated substrate peptides were separated and analyzed
through a LabChip EZ Reader. The IC50 of 9 in this assay was
1.92 μM. Further SAR exploration to improve the potency of 9 is
currently ongoing and will be reported in due course.
Table 1. SNAr Substitution and Coupling Reactions of 1
12
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
Table 1. continued
a
b
c
1.5 equiv phenol, 3.0 equiv K2CO3, DMF, μW, 175 °C, 50 min. 1.2 equiv NaH, 2.0 equiv propanol, THF, μW, 120 °C, 20 min. 1.2 equiv
d
e
aniline/amine, iPrOH, 80 °C, overnight. 1.5 equiv boronic acid, 5% Pd(PPh3)4, DMF/H2O, μW, 150 °C, 15 min. 3 equiv benzylzinc bromide,
toluene, 10% Pd(PPh3)4, 100 °C, overnight.
Scheme 3. Introduction of Secondary Amine Groups at the C7 Position of Pyrrolopyrimidines
Scheme 4. Introduction of Tertiary Amines and Amide Groups at the C7 Position of 8
reaction, cross-coupling reaction, one-pot reduction/reductive
amination and N-alkylation reaction. These reactions occur
rapidly with high yields and have broad substrate scopes. A
variety of R2 and R3 groups can be selectively introduced into
CONCLUSION
■
In summary, we have developed an efficient and robust route to
prepare 4,5,7-trisubstituted pyrrolopyrimidines from the com-
mon intermediate 1. The synthesis features a SNAr substitution
13
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
Table 2. N-Alkylation at the N5 Position of 7
a
b
1.5 equiv R3X, DMF, μW, 150 °C, 15 min. In product 11c, the Boc group on the aniline nitrogen has been removed as well under the treatment of
c
TFA. 3 equiv halide, DMF, μW, 150 °C, 30 min.
4,5,7-trisubstituted pyrrolopyrimidines at a late stage of the syn-
thesis. This synthetic strategy is highly desirable when large numbers
of 4,5,7-trisubstituented pyrrolopyrimidine analogues are needed in
high yields and purity for SAR development via biological evalua-
tion. In addition, a new and selective FLT3 inhibitor 9 has been
identified from the synthesized pyrrolopyrimidine analogues.
EXPERIMENTAL PROCEDURES
■
General Experimental Details. All reagents were commer-
cially available and used without any further purification. Micro-
wave reaction was carried out using a Discover-S reactor with a
vertically focused IR external temperature sensor and an Explorer
14
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
Scheme 5. Selective N-Alkylation at N5 Position in 4h
72 autosampler. The dynamic mode was used to set up the
desired temperature and hold time with the following fixed
parameters: PreStirring, 1 min; Pressure, 200 psi; Power, 200 W;
PowerMax, off; Stirring, high. Flash chromatography was carried
out on Teledyne ISCO Combi Flash Rf using prepacked silica gel
disposable columns. A gradient from 0% to 100% ethylacetate
(100−0% hexane) for nonpolar compounds or to 20% methanol
(100−80% CH2Cl2) for polar compounds was used as elutes.
Analytical thin-layer chromatography (TLC) was performed
with silica gel 60 F254, 0.25 mm precoated TLC plates. TLC
plates were visualized using UV254 or phosphomolybdic acid with
pyrimidine (2) (1.6 g), which was used directly for the next step.
A mixture of 2 (1.6 g, 4.88 mmol), [1,1′-biphenyl]-4-ol (1.66 g,
9.76 mmol), and K2CO3 (2.02 g, 14.64 mmol) in 25 mL of DMF
was stirred for 5.0 h at room temperature. The reaction was
quenched by water and extracted with ether (3×). The combined
organic layers were dried (Na2SO4) and concentrated. The residue
was purified by column chromatography with ISCO system to
provide the title compound 3 (2.1 g, 91% over 2 steps) as a light
yellow solid. 1H NMR (400 MHz, CDCl3) δ 8.78 (s, 1H), 8.45 (s,
1H), 7.73−7.67 (m, 2H), 7.63−7.58 (m, 2H), 7.49−7.43 (m, 2H),
7.40−7.35 (m, 1H), 7.34−7.29 (m, 2H), 5.87 (s, 2H), 3.77−3.65
(m, 2H), 1.03−0.93 (m, 2H), −0.02 (s, 9H); 13C NMR (101 MHz,
CDCl3) δ 156.3, 154.0, 150.8, 144.1, 140.2, 139.8, 133.8, 129.1,
129.0, 128.7, 127.7, 127.3, 122.1, 115.2, 79.4, 67.8, 18.0, −1.3; LC-
MS (ESI+) tR = 6.285 min, m/z 463.2 [M + 1]+.
7-Nitro-4-phenoxy-5H-pyrrolo[3,2-d]pyrimidine (4a). Gen-
eral Procedure A. A 10 mL microwave tube was charged with 1
(92 mg, 0.46 mmol), K2CO3 (193 mg, 1.4 mmol), anhydrous
DMF (2.5 mL), and phenol (66 mg, 0.70 mmol). The resulting
mixture was heated at 175 °C for 50 min under microwave
irradiation. After it was cooled to room temperature, the reaction
mixture was diluted with EtOAc and water. The aqueous phase
was extracted with EtOAc (3×). The combined organic extracts
were washed with brine and dried (Na2SO4), concentrated under
reduced pressure. The residue was purified by column chro-
matography with ISCO system to provide the title compound 4a
(88 mg, 75%) as a white solid. 1H NMR (400 MHz, DMSO-d6) δ
13.83 (s, 1H), 8.94 (s, 1H), 8.56 (s, 1H), 7.52−7.45 (m, 2H),
7.35−7.28 (m, 3H); 13C NMR (101 MHz, DMSO-d6) δ 156.2,
153.0, 152.1, 143.3, 134.3, 130.3, 128.3, 126.4, 122.5, 115.1;
HRMS (TOF, ESI+) m/z [M + H]+ calculated for C12H9N4O3,
257.0675; found 257.0659.
1
charring. All H NMR spectra were obtained with a 400 MHz
spectrometer and 13C NMR spectra were obtained with a 101
MHz spectrometer. Preparative HPLC was performed with the
UV detection at 220 or 254 nm. LC-MS was performed with the
UV detection at 220 nm, 254 nm, and 280 nm, and a single
quadrupole mass spectrometer using electrospray ionization
(ESI) source. High-resolution (positive ion) mass spectra
(HRMS) were acquired using a LCMS-TOF mass spectrometer.
4-Chloro-7-nitro-5H-pyrrolo[3,2-d]pyrimidine (1). The sol-
ution of 7-nitro-3H-pyrrolo[3,2-d]pyrimidin-4(5H)-one (5.0 g,
27.8 mmol) in POCl3 (12.6 g, 83.3 mmol) was heated under
reflux for 5.0 h. Then the mixture was cooled to room tempera-
ture and poured onto the chipped ice with vigorous stirring, then,
basified with K2CO3 to PH 8−9. The resulting mixture was
filtered and washed with water (2×) and EtOAc (3×) to provide
1
the title compound (4.5 g, 82%) as yellow powder. H NMR
(400 MHz, DMSO-d6) δ 9.11 (s, 1H), 8.90 (s, 1H); 13C NMR
(101 MHz, DMSO-d6) δ 153.1, 144.7, 142.8, 137.1, 128.1, 124.6;
HRMS (TOF, ESI+) m/z [M + H]+ calculated for C6H4ClN4O2,
199.0023; found 198.9869
4-([1,1′-Biphenyl]-4-yloxy)-7-nitro-5-((2-(trimethylsilyl)-
ethoxy)methyl)-5H-pyrrolo[3,2-d]pyrimidine (3). To a DMF
(10 mL) solution of 1 (1.0 g, 5.0 mmol) and SEMCl (1.1 mL, 6.0
mmol) was added NaH (0.4 g, 60 wt % in mineral oil, 10 mmol)
at 0 °C. The resulting mixture was warmed to room temperature
and stirred overnight. The reaction was quenched by water. The
aqueous phase was extracted by ether (2×) and EtOAc (2×).
The combined organic layers were dried (Na2SO4) and concen-
trated. The residue was passed a short silica pad to provide 4-chloro-
7-nitro-5-((2-(trimethylsilyl)ethoxy)methyl)-5H-pyrrolo[3,2-d]-
7-Nitro-4-propoxy-5H-pyrrolo[3,2-d]pyrimidine (4f). To a
suspension of NaH (23.1 mg, 60% in mineral oil, 0.57 mmol)
in anhydrous THF (2.0 mL) was added propanol (57.6 mg,
0.96 mmol) at 0 °C in a 10 mL microwave tube. After it was
stirred for 30 min at 0 °C, 1 (95 mg, 0.48 mmol) was added, and
the resulting mixture was heated at 120 °C for 20 min under
microwave irradiation. After it was cooled to room temperature,
the reaction was diluted with EtOAc and water. The aqueous
phase was extracted with EtOAc (3×). The combined organic
15
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
extracts were dried (Na2SO4) and concentrated under reduced
pressure. The residue was purified by column chromatography
with ISCO system to provide the title compound 4f (77 mg, 72%)
as a white solid. 1H NMR (400 MHz, DMSO-d6) δ 13.49 (s, 1H),
8.76 (s, 1H), 8.61 (s, 1H), 4.49 (t, J = 6.6 Hz, 2H), 1.86−1.76
(m, 2H), 1.01 (t, J = 7.4 Hz, 3H); 13C NMR (101 MHz, DMSO-d6)
δ 156.6, 153.3, 142.2, 133.2, 128.2, 115.0, 68.4, 22.2, 10.7; HRMS
(TOF, ESI+) m/z [M + H]+ calculated for C9H11N4O3, 223.0831;
found 223.0810.
0.10 mmol) and Pd/C (4.6 mg, 10 wt % Pd/C) in MeOH
(5.0 mL) was added a solution of acetaldehyde (4.4 mg, 0.10 mmol)
in MeOH (0.5 mL) drop-wisely under hydrogen atmosphere. After
4.0 h, the resulting mixture was filtered over a Celite pad and
washed with MeOH. After removal of MeOH solvent, the crude
product was dissolved in 2.0 mL CH2Cl2. To this solution was
added Et3N (20 mg, 0.20 mmol) and Boc2O (65 mg, 0.3 mmol).
The reaction was stirred 6.0 h at room temperature and quen-
ched with a saturated aqueous NH4Cl solution. After extraction
with CH2Cl2 (3×), the combined organic layers were con-
centrated. The resulting residue was purified by a short silica
column to provide 6 (50 mg), which was used directly for
the next step. To a solution of 6 (50 mg, 0.088 mmol) in THF
(0.5 mL) was added a solution of TBAF (0.22 mL, 1.0 M in THF,
0.22 mmol) and ethylenediamine (6.6 mg, 0.11 mmol) at room
temperature. After refluxing for 1.0 h, the reaction mixture was
diluted with EtOAc and washed with water. The combined
organic layers are dried (Na2SO4) and concentrated. The residue
was purified by column chromatography with ISCO system to
provide the title compound 7 (25 mg, 58% over 3 steps) as a light
yellow solid. 1H NMR (400 MHz, CD3OD) δ 8.50 (bs, 1H),
7.86 (bs, 1H), 7.77−7.70 (m, 2H), 7.68−7.62 (m, 2H), 7.49−
7.43 (m, 2H), 7.42−7.33 (m, 3H), 3.74 (q, J = 7.1 Hz, 2H), 1.46
(bd, 9H), 1.20 (bs, 3H); LC-MS (ESI+) tR = 5.927 min, m/z
431.2 [M + 1]+.
N-Butyl-7-nitro-5H-pyrrolo[3,2-d]pyrimidin-4-amine (4g).
General Procedure B. To a solution of 1 (200 mg, 1.01 mmol)
in anhydrous i-PrOH (15 mL) was added butylamine (89 mg,
1.21 mmol). The resulting mixture was heated at 80 °C for over-
night under nitrogen atmosphere. After cooling to room tem-
perature, the reaction was diluted with EtOAc and water. The
aqueous phase was extracted with EtOAc (3×). The combined
organic extracts were and washed with brine and dried (Na2SO4),
concentrated under reduced pressure. The residue was purified
by column chromatography with ISCO system to provide the
1
title compound 4g (215 mg, 92%) as a yellow solid. H NMR
(400 MHz, CDCl3 + CD3OD) δ 8.21 (s, 1H), 8.05 (s, 1H), 3.55
(t, J = 7.1 Hz, 2H), 1.64−1.56 (m, 2H), 1.42 − 1.33 (m, 2H), 0.89
(t, J = 7.4 Hz, 3H); 13C NMR (101 MHz, CDCl3 + CD3OD) δ
151.8, 147.4, 129.9, 127.3, 125.2, 112.8, 41.1, 30.6, 19.6, 12.6;
HRMS (TOF, ESI+) m/z [M + H]+ calculated for C10H14N5O2,
236.1147; found 236.1128.
N4-Butyl-5H-pyrrolo[3,2-d]pyrimidine-4,7-diamine (8). The
solution of 4g (85 mg, 0.36 mmol) and 10% palladium on actived
carbon (53.9 mg, 0.30 mmol) in MeOH (15.0 mL) was stirred
under hydrogen atmosphere at room temperature for 3.0 h. Then
the reaction mixture was filtered though a pad of Celite to afford
7-Nitro-4-phenyl-5H-pyrrolo[3,2-d]pyrimidine (4j). General
procedure C. A 10 mL microwave tube was charged with 1
(150 mg, 0.76 mmol), K2CO3 (262 mg, 1.90 mmol), phenyl-
boronic acid (139 mg, 1.14 mmol), Pd(PPh3)4 (44 mg, 0.038 mmol),
DMF (2.0 mL) and H2O (1.0 mL). The resulting mixture was stirred
at room temperature for 3.0 min and then heated at 150 °C for
15 min. After it was cooled to room temperature, the mixture was
partitioned in H2O and Et2O. The aqueous phase was extracted with
Et2O (3×). The combined organic layers were dried (Na2SO4) and
concentrated under reduced pressure. The residue was purified by
column chromatography with ISCO system to provide the title
compound 4j (159 mg, 87%) as a white solid. 1H NMR (400 MHz,
DMSO-d6) δ 9.14 (s, 1H), 9.00 (s, 1H), 8.05−8.01 (m, 2H), 7.64−
7.60 (m, 3H); 13C NMR (101 MHz, DMSO-d6) δ 153.7, 151.0,
142.8, 136.8, 135.0, 131.4, 129.5, 129.4, 129.2, 127.7; HRMS (TOF,
ESI+) m/z [M + H]+ calculated for C12H9N4O2, 241.0726; found
241.0719.
4-Benzyl-7-nitro-5H-pyrrolo[3,2-d]pyrimidine (4o). General
Procedure D. To a solution of 1 (96 mg, 0.48 mmol) and
Pd(PPh3)4 (112 mg, 0.097 mmol) in anhydrous toluene (12 mL)
was added a 0.5 M solution of benzylzinc(II) bromide in THF
(2.0 mL) at room temperature. The resulting mixture was heated
at 110 °C for 12 h and quenched by water (4.0 mL). The solvent
was removed under the reduced pressure. The residue was dis-
solved in water and extracted with EtOAc (3×). The combined
organic layers were dried (Na2SO4), and concentrated under
reduced pressure. The residue was purified by column chro-
matography with ISCO system to give the title compound 4o
(78 mg, 64%) as a yellow solid. 1H NMR (400 MHz, CD3OD +
CDCl3) δ 9.00 (s, 1H), 8.43 (s, 1H), 7.25−7.11 (m, 5H), 4.35
(s, 2H); 13C NMR (101 MHz, CD3OD+CDCl3) δ 154.5, 153.4,
141.3, 136.1, 133.8, 128.7, 128.7, 127.1, 125.7, 39.2; LC-MS
(ESI+) tR = 4.558 min, m/z 255.10 [M + 1]+; HRMS (TOF,
ESI+) m/z [M + H]+ calculated for C13H11N4O2, 255.0882;
found 255.0879.
1
the title compound 8 (68 mg, 92%) as a brown oil. H NMR
(400 MHz, CD3OD) δ 8.20 (s, 1H), 7.03 (s, 1H), 3.58 (t, J = 7.1 Hz,
2H), 1.75 − 1.60 (m, 3H), 1.56 − 1.43 (m, 2H), 0.99 (t, J = 7.4 Hz,
3H); 13C NMR (101 MHz, CD3OD) δ 150.0, 147.5, 135.2,
121.6, 114.9, 112.6, 40.1, 31.2, 19.7, 12.7; HRMS (TOF, ESI+) m/z
[M + H]+ calculated for C10H16N5, 206.1406; found 206.1396.
N-Butyl-7-(piperazin-1-yl)-5H-pyrrolo[3,2-d]pyrimidin-4-
amine (9). Bis(2-chloroethyl)amine (95.6 mg, 0.54 mmol) was
added into the solution of 8 (110.1 mg, 0.54 mmol) in i-PrOH
(10.0 mL) at room temperature. Then Na2CO3 (114.5 mg, 1.1
mmol) was added, the resulting reaction mixture was stirred
overnight at reflux. Then water (20 mL) was added and extracted
with dichloromethane (3×). The combined organic layers
were dried (Na2SO4), filtered, and condensed. The residue was
purified by column chromatography with ISCO system to pro-
vide the title compound 9 (118.9 mg, 81%) as red oil. 1H NMR
(400 MHz, CD3OD) δ 8.13 (s, 1H), 6.98 (s, 1H), 3.52 (t, J =
7.1 Hz, 2H), 3.17−3.08 (m, 4H), 3.09−2.99 (m, 4H), 1.72−1.62
(m, 2H), 1.51−1.42 (m, 2H), 0.98 (t, J = 7.4 Hz, 3H); 13C NMR
(101 MHz, CD3OD) δ 150.0, 148.4, 137.9, 130.8, 113.8,
113.5, 51.7, 44.7, 40.0, 31.2, 19.8, 12.7; HRMS (TOF, ESI+) m/z
[M + H]+ calculated for C14H23N6, 275.1984; found 275.1978.
N-(4-(Butylamino)-5H-pyrrolo[3,2-d]pyrimidin-7-yl)-
benzamide (10a). General Procedure E. To the solution of 8
(0.30 mmol, 1.0 equiv), DIEA (0.45 mmol, 1.5 equiv) and dichlo-
romethane (3.0 mL) was added benzoyl chloride (13 mg, 0.090
mmol) at room temperature. After it was stirred for 8.0 h at room
temperature, the reaction was quenched with a sat. NaHCO3
solution (5.0 mL) and extracted with dichloromethane (3×).
The combined organic phases were dried (Na2SO4), filtered and
concentrated under the reduced pressure. The residue was
purified through prep-HPLC to provide the title compound 10a
(10 mg, 39%) as a white solid. 1H NMR (400 MHz, CDCl3) δ
tert-Butyl (4-([1,1′-biphenyl]-4-yloxy)-5H-pyrrolo[3,2-d]-
pyrimidin-7-yl)(ethyl)carbamate (7). A mixture of 3 (46 mg,
16
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
12.78 (s, 1H), 10.45 (s, 1H), 8.85 (d, J = 5.5 Hz, 1H), 8.23
(s, 1H), 8.02−7.92 (m, 2H), 7.81 (d, J = 2.9 Hz, 1H), 7.49 (t, J =
7.4 Hz, 1H), 7.38 (t, J = 7.7 Hz, 2H), 3.64 (dd, J = 13.0, 7.2 Hz,
2H), 1.69−1.62 (m, 2H), 1.40 (dq, J = 14.6, 7.3 Hz, 2H), 0.93
(t, J = 7.4 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ 166.5, 151.6,
142.9, 132.4, 132.3, 128.6, 127.7, 124.3, 120.9, 112.7, 112.5, 41.5,
30.9, 19.9, 13.6; HRMS (TOF, ESI+) m/z [M + H]+ calculated
for C17H20N5O, 310.1668; found 310.1664.
4.44 (d, J = 7.3 Hz, 2H), 3.93−3.84 (m, 2H), 3.34 (s, 3H), 1.93
(d, J = 10.7 Hz, 2H), 1.69 (d, J = 11.9 Hz, 2H), 1.42 (s, 9H), 1.32
(t, J = 7.2 Hz, 3H), 1.25−1.13 (m, 4H); 13C NMR (101 MHz,
CD3OD) δ 156.4, 150.3, 145.7, 136.1, 128.8, 128.5, 127.5, 127.2,
123.9, 118.8, 111.1, 78.5, 56.2, 52.0, 49.4, 48.4, 44.5, 39.5, 37.8,
31.7, 28.2, 27.4, 12.4; HRMS (TOF, ESI+) m/z [M + H]+
calculated for C27H39N6O2, 479.3134; found 479.3128.
tert-Butyl ((1r,4r)-4-((4-(Ethyl(phenethyl)amino)-7-(4-me-
thoxybenzamido)-5H-pyrrolo[3,2-d]pyrimidin-5-yl)methyl)-
cyclohexyl)carbamate (14). To a solution of 13 (80 mg,
0.17 mmol), triethyl amine (25.3 mg, 0.25 mmol), catalytic amount
of DMAP in anhydrous THF (3.0 mL) was added 4-metho-
xybenzoyl chloride (28.4 mg, 0.17 mmol) at room temperature. The
resulting mixture was stirred for 5.0 h and quenched with water and
diluted with EtOAc (20 mL). The aqueous phase was extracted with
EtOAc (3×). The combined organic phase was dried (Na2SO4),
filtered and condensed. The residue was purified by column
chromatography with ISCO system to give the title compound
4-([1,1′-Biphenyl]-4-yloxy)-N-ethyl-5-(3-morpholinoprop-
yl)-5H-pyrrolo[3,2-d]pyrimidin-7-amine (11a). General Pro-
cedure F. A mixture of 7 (65 mg, 0.15 mmol), K2CO3 (62 mg,
0.45 mmol), 4-(3-chloropropyl)morpholine (40 mg, 0.23 mmol),
and DMF (2 mL) in a microwave tube was heated under
microwave irradiation at 150 °C for 10 min. After it was cooled
to room temperature, the mixture was washed with brine and
extracted with EtOAc (3×). The combined organic layers was
dried (Na2SO4) and concentrated. The residue was puri-
fied by column chromatography with ISCO system to pro-
vide the desired intermediate. This intermediate was dissolved in
a mixture of 2.0 mL of CH2Cl2 and 0.5 mL of TFA. After it was
stirred at room temperature for 2.0 h, the solution was con-
centrated and purified through prep-HPLC to provide the title
compound 11a (64 mg, 93%) as a yellow oil. 1H NMR
(400 MHz, CD3OD) δ 8.43 (s, 1H), 8.08 (s, 1H), 7.77−7.70 (m, 2H),
7.67−7.60 (m, 2H), 7.48−7.32 (m, 5H), 4.67 (t, J = 7.0 Hz, 2H),
3.97 (bs, 2H), 3.76 (bs, 2H), 3.65 (q, J = 7.3 Hz, 2H), 3.48 (bs,
2H), 3.30−3.24 (m, 2H), 3.11 (bs, 2H), 2.54−2.39 (m, 2H), 1.40
(t, J = 7.3 Hz, 3H); 13C NMR (100 MHz, CD3OD) δ 157.0,
152.6, 151.2, 145.23, 141.4, 140.6, 130.0, 129.4, 128.6, 128.0,
123.5, 116.6, 116.0, 113.6, 64.9, 55.4, 53.1, 47.9, 47.1, 27.1, 11.7;
HRMS (TOF, ESI+) m/z [M + H]+ calculated for C27H32N5O2,
458.2556; found 458.2536.
tert-Butyl ((1r,4r)-4-((4-(Benzyl(ethyl)amino)-7-nitro-5H-
pyrrolo[3,2-d]pyrimidin-5-yl)methyl)cyclohexyl)carbamate
(12). A 10 mL microwave tube was charged with 4h (297 mg,
1.0 mmol), K2CO3 (345 mg, 2.5 mmol), DMF (2.0 mL), and
trans-tert-butyl (4-(bromomethyl)cyclohexyl)carbamate (436 mg,
1.5 mmol). The resulting mixture was heated at 150 °C for 45 min
under microwave irradiation. After it was cooled to room tem-
perature, the reaction was diluted with EtOAc and washed with
brine. The aqueous phase was extracted with EtOAc (3×). The
combined organic extracts were dried (Na2SO4) and concentrated
under reduced pressure. The residue was purified by column
chromatography with ISCO system to provide the title compound
12 (361 mg, 71%) as a white solid. 1H NMR (400 MHz, CD3OD)
δ 8.50 (s, 1H), 7.44−7.22 (m, 6H), 4.61 (d, J = 6.9 Hz, 2H), 3.34
(s, 5H), 1.91 (d, J = 11.9 Hz, 2H), 1.69−1.60 (m, 3H), 1.41 (s, 9H),
1.34−1.29 (m, 3H), 1.20−1.08 (m, 4H); 13C NMR (101 MHz,
CD3OD) δ 156.3, 151.9, 147.3, 138.8, 136.3, 128.5, 128.2, 127.5,
127.4, 125.8, 110.0, 78.6, 59.5, 52.1, 49.3, 48.7, 44.5, 37.1, 31.8, 28.1,
27.6; HRMS (TOF, ESI+) m/z [M + H]+ calculated for C27H37N6O4,
509.2876; found 509.2869.
1
14 (53 mg, 51% yield) as a yellow solid. H NMR (400 MHz,
CDCl3) δ 7.90 (d, J = 7.8 Hz, 2H), 7.65 (s, 1H), 7.56 (s, 1H),
7.35−7.19 (m, 5H), 6.94 (d, J = 8.7 Hz, 2H), 5.29 (s, 2H), 5.13 −
5.00 (m, 1H), 4.44 (s, 1H), 3.96 (d, J = 6.9 Hz, 2H), 3.86 (s, 3H),
3.37−3.25 (m, 1H), 1.94−1.81 (m, 3H), 1.51−1.45 (m, 2H),
1.41 (s, 9H), 1.35−1.18 (m, 3H), 0.96 (t, J = 9.7 Hz, 4H); 13
C
NMR (101 MHz, CD3OD) δ 169.1, 163.0, 156.4, 151.3,
142.8, 137.9, 131.0, 129.2, 128.1, 127.3, 127.0, 125.6, 113.5, 105.7,
78.5, 56.3, 54.6, 36.7, 31.6, 28.6, 27.3; HRMS (TOF, ESI+) m/z
[M + H]+ calculated for C35H45N6O4, 613.3502; found 613.3498.
N-(5-(((1r,4r)-4-Aminocyclohexyl)methyl)-4-(ethylamino)-
5H-pyrrolo[3,2-d]pyrimidin-7-yl)-4-methoxybenzamide (15).
To a solution of compound 14 (46 mg, 0.075 mmol) in methanol
(5.0 mL) was added 10% palladium on activated carbon (5 mg,
0.0047 mmol) at room temperature. The resulting mixture was
added 3 drops of acetic acid and was then heat at 60 °C under H2
atmosphere for 6.0 h. The reaction mixture was then diluted with
EtOAc (20 mL) and filtered though a pad of Celite. The solvent
was removed and the residue was purified by column chro-
matography with ISCO system to give the debenzylated inter-
1
mediate (22 mg, 56%) as a white solid. H NMR (400 MHz,
CD3OD) δ 8.47 (s, 1H), 8.02 (d, J = 8.9 Hz, 2H), 7.82 (s, 1H),
7.09 (d, J = 8.9 Hz, 2H), 4.28 (d, J = 7.2 Hz, 2H), 3.89 (s, 3H),
3.80 (q, J = 7.2 Hz, 2H), 2.97 (s, 1H), 1.79−1.76 (m, 4H), 1.50
(s, 2H), 1.37 (t, J = 7.3 Hz, 3H), 1.24−1.07 (m, 5H); 13C NMR
(101 MHz, CD3OD) δ 169.1, 163.5, 150.7, 148.1, 129.8, 129.3,
124.6, 113.7, 112.8, 109.1, 56.6, 54.7, 37.1, 36.1, 31.5, 28.4, 27.3,
13.0. To a solution of the debenzylated intermediate (15 mg,
0.029 mmol) in dichloromethane (5.0 mL) was added trifluoro-
acetic acid (32.7 mg, 0.29 mmol) at room temperature. The
resulting mixture was heated at 60 °C for 4.0 h. Then the reaction
was diluted with dichloromethane (22.0 mL) and washed with
NaHCO3 (sat.), water and brine sequentially. The organic phase
was dried (Na2SO4), filtered, and condensed. The residue was
purified through preparative HPLC to give the title compound
tert-Butyl ((1r,4r)-4-((7-amino-4-(benzyl(ethyl)amino)-5H-
pyrrolo[3,2-d]pyrimidin-5-yl)methyl)cyclohexyl)carbamate
(13). To a suspension of 10% palladium on active carbon (13 mg,
0.013 mmol) in methanol (8.0 mL) was added 12 (125 mg,
0.25 mmol) at room temperature. The resulting mixture was
stirred under hydrogen atmosphere for 3.0 h. Then the mixture
was diluted with EtOAc and filtered through a pad of Celite and
condensed. The residue was purified by column chromatography
with ISCO system to provide the title compound 13 (100 mg,
1
15 (9.2 mg, 75% yield) as a clear oil. H NMR (400 MHz,
CD3OD) δ 8.47 (s, 1H), 8.02 (d, J = 8.9 Hz, 2H), 7.82 (s, 1H),
7.09 (d, J = 8.9 Hz, 2H), 4.28 (d, J = 7.2 Hz, 2H), 3.89 (s, 3H),
3.80 (q, J = 7.2 Hz, 2H), 2.97 (s, 1H), 1.95−1.75 (m, 4H), 1.50
(s, 2H), 1.53−1.46 (m, 3H), 1.24−1.07 (m, 5H); 13C NMR (101
MHz, CD3OD) δ 168.9, 163.5, 150.8, 148.0, 130.1, 129.8, 129.3,
124.5, 113.8, 112.8, 108.9, 56.1, 54.7, 49.5, 36.5, 36.1, 29.3, 27.4,
13.0; HRMS (TOF, ESI+) m/z [M + H]+ calculated for
C23H31N6O2, 423.2508; found 423.2518.
1
84%) as a green oil. H NMR (400 MHz, CD3OD) δ 8.35
(s, 1H), 7.41 (d, J = 4.6 Hz, 1H), 7.37−7.26 (m, 5H), 5.17 (s, 2H),
17
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
(2) Oguro, Y.; Miyamoto, N.; Takagi, T.; Okada, K.; Awazu, Y.; Miki,
H.; Hori, A.; Kamiyama, K.; Imamura, S. N-Phenyl-N′-[4-(5H-
pyrrolo[3,2-d]pyrimidin-4-yloxy)phenyl]ureas as novel inhibitors of
VEGFR and FGFR kinases. Bioorg. Med. Chem. 2010, 18 (20), 7150−
7163.
(3) Saavedra, O. M.; Claridge, S. W.; Zhan, L.; Raeppel, F.; Vaisburg,
A.; Raeppel, S.; Deziel, R.; Mannion, M.; Zhou, N. Z.; Isakovic, L.
Thienopyridine and thienopyrimidine derivatives and their preparation,
pharmaceutical compositions, and use as inhibitors of VEGF receptor
and HGF receptor signaling for treatment of proliferative diseases. Int.
Patent WO2007054831A2, 2007.
(4) Blake, J. F.; Kallan, N. C.; Xiao, D.; Xu, R.; Bencsik, J. R.; Skelton,
N. J.; Spencer, K. L.; Mitchell, I. S.; Woessner, R. D.; Gloor, S. L.; Risom,
T.; Gross, S. D.; Martinson, M.; Morales, T. H.; Vigers, G. P. A.;
Brandhuber, B. J. Discovery of pyrrolopyrimidine inhibitors of Akt.
Bioorg. Med. Chem. Lett. 2010, 20, 5607−5612.
(5) Bluhm, H.; Hochguertel, M.; Kroth, H.; Essers, M.; Gege, C.;
Richter, F.; Taveras, A. Heterobicyclic matrix metalloprotease inhibitors,
their preparation, pharmaceutical compositions, and use in therapy. Int.
Patent WO2008063669A1, 2008.
(6) Flanagan, M. E.; Blumenkopf, T. A.; Brissette, W. H.; Brown, M. F.;
Casavant, J. M.; Chang, S.-P.; Doty, J. L.; Elliott, E. A.; Fisher, M. B.;
Hines, M.; Kent, C.; Kudlacz, E. M.; Lillie, B. M.; Magnuson, K. S.;
McCurdy, S. P.; Munchhof, M. J.; Perry, B. D.; Sawyer, P. S.; Strelevitz,
T. J.; Subramanyam, C.; Sun, J.; Whipple, D. A.; Changelian, P. S.
Discovery of CP-690,550: A potent and selective janus kinase (JAK)
inhibitor for the treatment of autoimmune diseases and organ transplant
rejection. J. Med. Chem. 2010, 53, 8468−8484.
Selectivity Profiling. The selected compounds were
screened against 48 kinases using the Profiler Pro Kit (Caliper
Life Sciences). Briefly, preplated enzyme stocks were recon-
stituted with 15 μL of supplied reconstitution buffer containing
DTT and Protease Inhibitor Cocktail. One microliter of com-
pound at a concentration of 260 μM in 100% DMSO was trans-
ferred to the plate and the reaction was initiated by the addition
of 10 μL substrate solution containing ATP and cofactors
specific for each enzyme. The reaction was incubated at room
temperature for 90 min and 45 μL of termination buffer was
then added to stop the reaction. The plates were read in a Caliper
EZ Reader.
Microfluidic Capillary Electrophoresis (MCE) Assay.
The activity assays were performed in a 384 well, polypropylene
microtiterplate, using 0.3 nM FLT-3 (Life Technologies catalog
PHC9415), in a final volume of 50 μL of 50 mM HEPES pH 7.4
containing 10 mM MgCl2, 1 mM DTT, 0.01% Triton X-100,
0.1% bovine serum albumin (BSA), 1 μM fluorescent peptide
substrate (5-FAM-KKKKEEIYFFF-CONH2) and 275 μM ATP
(at Km for Flt3). All reactions were terminated following a 60-min
incubation, by addition of 20 μL of 70 mM EDTA. Phosphory-
lated and unphosphorylated substrate peptides were separated
on a LabChip EZ Reader equipped with a 12-sipper chip in
separation buffer supplemented with CR-8 and analyzed using
EZ Reader software.
(7) Calderwood, D. J.; Johnston, D. N.; Munschauer, R.; Rafferty, P.
Pyrrolo[2,3-d]pyrimidines containing diverse N-7 substituents as
potent inhibitors of Lck. Bioorg. Med. Chem. Lett. 2002, 12 (12),
1683−6.
(8) Evans, G. B.; Furneaux, R. H.; Lenz, D. H.; Painter, G. F.; Schramm,
V. L.; Singh, V.; Tyler, P. C. Second generation transition state analogue
inhibitors of human 5′-methylthioadenosine phosphorylase. J. Med.
Chem. 2005, 48, 4679−4689.
ASSOCIATED CONTENT
■
S
* Supporting Information
Experimental procedures, characterization of all compounds and
biological methods, and copies of 1H and 13C spectra for all new
compounds. This material is available free of charge via the
Internet at http://pubs.acs.org.
(9) Morris, P. E., Jr.; Elliott, A. J.; Walton, S. P.; Williams, C. H.;
Montgomery, J. A. Synthesis and biological activity of a novel class of
purine nucleoside phosphorylase inhibitors. Nucleosides, Nucleotides
Nucleic Acids 2000, 19, 379−404.
(10) Girardet, J. L.; Koh, Y.-H.; Shaw, S.; Kin, H. W. Preparation of
purines, azapurines, and deazapurines as non-nucleoside reverse
transcriptase inhibitors for treatment of HIV infection. Int. Patent
WO2006122003A2, 2006.
(11) (a) Zhao, L.; Tao, K.; Li, H.; Zhang, J. Practical one-pot protocol
for the syntheses of 2-chloro-pyrrolo[3,2-d]pyrimidines. Tetrahedron
2011, 67, 2803−2806. (b) Norman, M. H.; Chen, N.; Chen, Z.; Fotsch,
C.; Hale, C.; Han, N.; Hurt, R.; Jenkins, T.; Kincaid, J.; Liu, L.; Lu, Y.;
Moreno, O.; Santora, V. J.; Sonnenberg, J. D.; Karbon, W. Structure−
activity relationships of a series of pyrrolo[3,2-d]pyrimidine derivatives
and related compounds as neuropeptide Y5 receptor antagonists. J. Med.
Chem. 2000, 43, 4288−4312.
(12) (a) Cherng, Y.-J. Synthesis of substituted pyridines by the
reactions of halopyridines with sulfur, oxygen and carbon nucleophiles
under focused microwave irradiation. Tetrahedron 2002, 58 (24), 4931−
4935. (b) Luo, G.; Chen, L.; Poindexter, G. S. Microwave-assisted
synthesis of aminopyrimidines. Tetrahedron Lett. 2002, 43 (33), 5739−
5742.
AUTHOR INFORMATION
■
Corresponding Author
*Tel: 919-843-8456. Fax: 919-843-8465. E-mail: xiaodonw@
unc.edu.
Author Contributions
X.W., W.Z., and J.L. conceived and designed the experiments,
W.Z. J.L., and M.S. performed the experiments, X.W., W.Z., and
J.L. wrote the manuscript and Supporting Information.
Funding
This work was supported by the University Cancer Research Fund,
School of Pharmacy, and Federal Funds from the National Cancer
institute, National Institute of Health, under Contract No.
HHSN261200800001E. The content of this publication does not
necessarily reflect the views or policies of the Department of Health
and Human Services nor does mention of trade names, commercial
products, or organizations imply endorsement by the U.S.
Government.
Notes
The authors declare no competing financial interest.
(13) Miyaura, N.; Yamada, K.; Suzuki, A. A new stereospecific cross-
coupling by the palladium-catalyzed reaction of 1-alkenylboranes with 1-
alkenyl or 1-alkynyl halides. Tetrahedron Lett. 1979, 3437−3440.
(14) King, A. O.; Okukado, N.; Negishi, E. Highly general stereo-,
regio-, and chemo-selective synthesis of terminal and internal
conjugated enynes by the palladium-catalyzed reaction of alkynylzinc
reagents with alkenyl halides. J. Chem. Soc., Chem. Commun. 1977, 683−
684.
ACKNOWLEDGMENTS
■
We thank Professor Stephen Frye for comments on manuscript
and Professor K. H. Lee’s lab for HRMS support.
REFERENCES
■
(15) Bambuch, V.; Otmar, M.; Pohl, R.; Masojidkova, M.; Holy, A. C-
Functionalization of 9-deazapurines by cross-coupling reactions.
Tetrahedron 2007, 63, 1589−1601.
(1) Imamura,S.; Oguro, Y. Preparation of fused heterocyclic derivatives,
particularly pyrrolo[3,2-d]pyrimidines and pyrrolo[3,2-b]pyridines, and
their use for treating cancer. Int. Patent WO2007004749A1, 2007.
18
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19

ACS Combinatorial Science
Research Article
(16) Wiernik, P. H. FLT3 inhibitors for the treatment of acute myeloid
leukemia. Clin. Adv. Hematol. Oncol. 2010, 8 (6), 429-36−444.
(17) (a) Pommereau, A.; Pap, E.; Kannt, A. Two simple and generic
antibody-independent kinase assays: comparison of a bioluminescent
and a microfluidic assay format. J. Biomol. Screening 2004, 9 (5), 409−16.
(b) Dunne, J.; Reardon, H.; Trinh, V.; Li, E.; Farinas, J. Comparison of
on-chip and off-chip microfluidic kinase assay formats. Assay Drug Dev.
Technol. 2004, 2 (2), 121−9. (c) Bernasconi, P.; Chen, M.; Galasinski,
S.; Popa-Burke, I.; Bobasheva, A.; Coudurier, L.; Birkos, S.; Hallam, R.;
Janzen, W. P. A chemogenomic analysis of the human proteome:
Application to enzyme families. J. Biomol. Screening 2007, 12 (7), 972−
82.
19
dx.doi.org/10.1021/co300106f | ACS Comb. Sci. 2013, 15, 10−19