Solid-phase synthesis of tetrasubstituted pyrrolo[2,3-d]pyrimidines

Article abstract of DOI:10.1039/c2ob06899k

A facile solid phase synthesis of 2,4,6,7-tetrasubstituted pyrrolo[2,3-d]pyrimidines is described. The synthesis involves a highly efficient five-step route starting from resin-bound dimeric peptoids. To demonstrate the versatility of our method, a representative library of 108 tetrasubstituted pyrrolo[2,3-d]pyrimidines of high quality was synthesized.

Full text of DOI:10.1039/c2ob06899k

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PAPER
Solid-phase synthesis of tetrasubstituted pyrrolo[2,3-d]pyrimidines†
Ji Hoon Leea and Hyun-Suk Lim*a,b
Received 10th November 2011, Accepted 2nd April 2012
DOI: 10.1039/c2ob06899k
A facile solid phase synthesis of 2,4,6,7-tetrasubstituted pyrrolo[2,3-d]pyrimidines is described. The
synthesis involves a highly efficient five-step route starting from resin-bound dimeric peptoids. To
demonstrate the versatility of our method, a representative library of 108 tetrasubstituted pyrrolo[2,3-d]
pyrimidines of high quality was synthesized.
Introduction
The pyrrolo[2,3-d]pyrimidine scaffold is considered a privileged
structure1 and is frequently found in numerous biologically
active molecules, including protein kinase inhibitors,2–7 E1
enzyme inhibitors,8 insulin-like growth factor 1 receptor inhibi-
Fig. 1 Structures of 2,6,7-trisubstituted (1) and 2,4,6,7-tetrasubstituted
tors,9 antibiotics,10 STAT6 inhibitors,11 deazapurine nucleo-
sides,12 microtubule targeting agents,13 and neurogenesis-
inducing molecules.14 Consequently, methods that allow for
efficient preparation of diversely functionalized pyrrolo[2,3-d]-
pyrimidines are of great interest in medicinal chemistry and
chemical biology. However, in contrast to other structurally
related privileged scaffolds,1 such as pyrrolo[3,2-d]pyrimi-
dines,15,16 purines17 and indoles,18 solid-phase methodology for
the preparation of pyrrolo[2,3-d]pyrimidines has yet to be
explored.
(2) pyrrolo[2,3-d]pyrimidines.
We have recently developed a solid-phase synthetic route for
2,6,7-trisubstituted pyrrolo[2,3-d]pyrimidine derivatives 1,
which were designed as α-helix mimetics (Fig. 1).19 This scaf-
fold has three points of diversification that could mimic the
spatial orientation of three key residues (i, i + 3 or i + 4, and
i + 7) on one face of an α-helix involved in protein–protein inter-
actions.20 As a result, suitably functionalized pyrrolo[2,3-d]pyri-
midine structures could serve as inhibitors of α-helix-mediated
protein–protein interactions. For solid-phase synthesis of the
designed scaffold 1, we utilized as a key intermediate dimeric
peptoids 5 (Scheme 1), which can be easily synthesized by a
standard submonomer route.21 The resin-bound peptoids 5 were
coupled with 4,6-dichloro-2-(methylthio)pyrimidine–carbalde-
hyde 6 to furnish 7. The formation of bicyclic pyrrolopyrimidine
Scheme 1 Solid-phase synthesis of 2,6,7-trisubstituted pyrrolo[2,3-d]
pyrimidines 1.
ring 8 was achieved by intramolecular aldol reaction and conco-
mitant dimethylamination at position 4. It is known that an acti-
vated chloride group on aromatic systems can be displaced with
a dimethylamino group by DMF under thermal conditions.22
Oxidation of the thioether 8 with m-chloroperbenzoic acid
(mCPBA), followed by amine displacement reaction afforded the
2,6,7-trisubstituted pyrrolo[2,3-d]pyrimidines 1 in good yields.
Using this method, we constructed a 900-member combinatorial
library of the trisubstituted pyrrolo[2,3-d]pyrimidines 1, in
which a few members of the library were identified as MDM2/
MDMX inhibitors.19 Despite the utility as α-helix mimetics, the
applicability of trisubstituted pyrrolo[2,3-d]pyrimidines 1 is
limited; they have three diversification points on the same face.
To expand the scope and versatility of the pyrrolo[2,3-d]pyrimi-
dine scaffold, herein we report the efficient and convenient solid
aDepartment of Biochemistry and Molecular Biology, and Indiana
University Simon Cancer Centre, Indiana University School of
Medicine, Indianapolis, Indiana 46202, USA
bDepartment of Chemistry, Pohang University of Science and
Technology (POSTECH), Pohang 790-784, South Korea.
E-mail: hslim@postech.ac.kr; Fax: +82-54-279-3399;
Tel: +82-54-279-2131
†Electronic supplementary information (ESI) available: Characterization
data of compounds 14 and 15. See DOI: 10.1039/c2ob06899k
This journal is © The Royal Society of Chemistry 2012
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Table 1 Results of cyclization
Scheme 2 Synthesis of 4-substituted pyrrolo[2,3-d]pyrimidine inter-
mediate 12.
phase synthesis of 2,4,6,7-tetrasubstituted pyrrolo[2,3-d]pyrimi-
dines 2.
Ratio of products
(%)b
Entry R4R4′NH
Conditionsa
7a 12
11
13
Results and discussion
1
2
DBU/NMP/60 °C
28
51
72
49
0
0
0
0
DBU/NMP-MeOH/
60 °C
DIEA/NMP/60 °C
Our initial synthetic strategy was to synthesize 4-chloropyrrolo-
pyrimidine 10 as an intermediate via cyclization of 7, which can
then be converted into 4-substituted pyrrolo[2,3-d]pyrimidines
12 by subsequent amination with R4R4′NH (Scheme 2). In our
previous work (Scheme 1), DMF acts both as a source of
dimethylamino group and as a solvent, generating pyrrolopyrimi-
dine ring 8 in one step from 7. Thus, we anticipated that the use
of an alternative solvent instead of DMF would provide a
cyclized product 10 without dimethylamination. Unexpectedly,
however, this cyclization reaction did not proceed under various
reaction conditions using different solvents such as DMSO, N-
methylpyrrolidone (NMP), and THF and bases such as 1,8-dia-
zabicyclo[5.5.0]undec-7-ene (DBU), N,N-diisopropylethylamine
(DIEA), Et3N, NaH, and NaOMe (Scheme 2). Given the fact
that cyclization occurs only in the presence of DMF, it is likely
that dimethylamine displacement of the chloride takes place first,
and the resulting dimethylamino group on the heterocycle then
facilitates the cyclization. Hence, we postulated that if an amine
is employed in the reaction, the cyclization can be achieved
along with the concurrent amination, thereby providing a desired
product 12 in one-pot reaction.
To test this hypothesis, we carried out the cyclization reaction
in the presence of various amines (R4R4′NH) to be introduced at
position 4 (Table 1). Indeed, treatment of aldehyde intermediate
7a with methoxyethylamine and DBU (as a base) in NMP or
NMP-MeOH led to the cyclized product 12. However, the reac-
tion was incomplete, yielding a large amount of remaining start-
ing material 7a (entries 1–2, Table 1). When using DIEA instead
of DBU, the yield was dramatically increased (entry 3, Table 1).
Encouraged by this result, we examined the reactivity with
different amines. However, the reaction with other amines such
as isobutylamine and dichlorophenethylamine gave a mixture of
aldehydes 11 and imine intermediates 13, with no cyclized pro-
ducts 12 (entries 4–5, Table 1). Elevating the reaction tempera-
ture resulted in a somewhat increased ratio of imines 13 over
aldehydes 11, but the intended products 12 were not observed
(entries 6–7, Table 1). Since the amino portion (dimethylamino
group) of DMF in our previous work (Scheme 1)19 is a second-
ary amine, it is possible to reason that the cyclized products 12
are formed via a reactive iminium intermediate, but not through
less active aldehydes 11 or imines 13 obtained from primary
3
4
0
0
98
0
2
0
DIEA/NMP/60 °C
DIEA/NMP/60 °C
71 29
77 23
5
0
0
6
7
DIEA/NMP/90 °C
DIEA/NMP/90 °C
0
0
0
0
49 51
45 55
8
9
DIEA/NMP/90 °C
DIEA/NMP/90 °C
0
0
0
0
100
0
0
100
0
10
11
(i) DIEA/NMP/60 °C
(ii) NaOMe/DMF/rt
(i) DIEA/NMP/60 °C
(ii) NaOMe/DMF/rt
0
0
100
100
0
0
0
12
13
14
15
(i) DIEA/NMP/60 °C
(ii) NaOMe/DMF/rt
(i) DIEA/NMP/60 °C
(ii) NaOMe/DMF/rt
(i) DIEA/NMP/60 °C
(ii) DBU/DMF/90 °C
(i) DIEA/NMP/60 °C
(ii) DBU/DMF/90 °C
0
0
0
0
100
100
100
100
0
0
0
0
0
0
0
0
a All reactions were carried out overnight. b Calculated from integrated
peak areas recorded by HPLC analysis.
amines (entries 1–7, Table 1). To test this, we employed second-
ary amines. The reaction with dimethylamine and morpholine
showed a similar result, giving aldehydes 11 with no trace of
cyclized products 12 or iminium intermediates (entries 8–9,
Table 1).
Given that both aldehydes 11 and imines 13 are the precursors
of pyrrolo[2,3-d]pyrimidines 12, it was envisaged that the use of
a stronger base would promote the intramolecular aldol reaction,
thereby converting the precursors into the product 12. Indeed,
treatment of the mixture of 11 and 13 with NaOMe afforded
exclusively 12 without any detectable by-products (entries
10–13, Table 1). Although the desired products 12 were success-
fully prepared using NaOMe, it remains unclear why in our
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Table 2 Purities of 4-substituted pyrrolo[2,3-d]pyrimidines 14a–h
Compd
14a
R2
–NR4R4′
Purity (%)a
99
99
14b
14c
97
14d
14e
98
96
14f
98
14g
14h
98
98
Fig. 2 Synthesis of 2,4,6,7-tetrasubstituted pyrrolo[2,3-d]pyrimidines
15 and representative HPLC traces for crude products 15.
(ESI,† Table S2), clearly demonstrating the robustness of our
solid-phase synthesis method. It is important to note that this
method is significantly more efficient in terms of yield and
purity, compared to our previous method which generates trisub-
stituted pyrrolo[2,3-d]pyrimidines in 80% purity on average.
Moreover, no detectable by-products were found in our new syn-
thetic strategy, whereas several impurities were inevitably
observed in our previous method.19 Hence, libraries constructed
by this method can be directly used for biological testing
without further purification.
a Purity of crude products assessed by HPLC.
previous work cyclization occurred without using a strong base.
To investigate this, the precursors (11 and 13) substituted with
different amines were subjected to the same reaction conditions
(DBU/DMF/90 °C). Remarkably, the reaction with DMF in the
presence of DBU furnished 12 in excellent yield (entries 14–15,
Table 1). Consequently, in accordance with our hypothesis, syn-
thesis of pyrrolopyrimidines 12 was accomplished by amination
and subsequent cyclization with either NaOMe or DBU/DMF.
To further assess the efficiency of this method, we synthesized
a series of compounds 14a–h by employing various amine
monomers (Table 2). The crude products released from resin
were analysed by LC/MS (ESI,† Fig. S1). Notably, compared to
the previous cyclization step (Scheme 1) that entails the pro-
duction of ∼5% of by-products,19 the new method was remark-
ably efficient, furnishing the products 14a–h in almost
quantitative yields in all cases (Table 2). The crude compounds
Conclusion
In conclusion, we developed a highly efficient and convenient
solid-phase synthetic pathway for the preparation of structurally
diverse 2,4,6,7-tetrasubstituted pyrrolo[2,3-d]pyrimidine deriva-
tives. This method not only generates the desired compounds in
remarkably excellent yields, but also offers a greater diversifica-
tion at four substitution positions. Importantly, our method uses
inexpensive and readily available amines as building blocks,
making it suitable for constructing a diversely functionalized
pyrrolo[2,3-d]pyrimidine library. Further work involving syn-
thesis of a large combinatorial library and biological testing is
currently in progress.
were purified by HPLC and further characterized by H and 13C
NMR spectroscopy (Fig. S2†) and high resolution mass spec-
trometry (HRMS).
1
To illustrate the versatility of our synthetic method, we con-
structed a 108-member combinatorial library of fully tetrasubsti-
tuted pyrrolo[2,3-d]pyrimidines 15 (Fig. 2) following the
method described above. We employed a variety of amines as
building blocks (9 R4R4′NH and 12 R3R3′NH) (ESI,† Table S1).
Synthesis of the 108 compounds was accomplished by a manual
parallel synthesis on MBHA Rink amide resin. After synthesis,
the cleaved crude compounds were characterized by LC/MS
(Fig. 2). The average purity of the library molecules was 93%
Experimental
General
Unless otherwise noted, all chemicals and reagents were pur-
chased from commercial suppliers and used without further
purification. Rink amide MBHA resin (0.75 mmol g−1) was
This journal is © The Royal Society of Chemistry 2012
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purchased from Novabiochem. LC/MS characterization was per-
formed using a C18 reversed phase HPLC column (2 μm,
4.6 mm × 50 mm). A gradient elution of 90% A in 2 min fol-
lowed by 100% B in 14 min was used at flow rate of 0.8 mL
min−1 (solvent A: 95% H2O, 5% MeOH, 0.01% TFA; B:
MeOH, 0.01% TFA). Reverse-phase HPLC purification was per-
formed with a C18 reversed-phase column (5 μm, 21.2 mm ×
125 mm) using a linear gradient from 10% B to 100% B by
changing solvent composition over 40 minutes. Peptoid syn-
thesis under microwave conditions was performed in a kitchen
microwave oven with 10% power. Thermal reactions were
carried out in a heating mantle filled with sea sand using 4 ml
glass vials.
(ESI) calculated for C24H33N6O3S [M + H]+ 485.2335, found:
485.2339.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-(cyclopentylamino)-7-(2-
methoxyethyl)-2-(methylthio)-7H-pyrrolo[2,3-d]pyrimidine-6-car-
boxamide·TFA (14b). 1H NMR (500 MHz, CDCl3) δ 1.36–1.68
(m, 8H), 2.59 (s, 3H), 3.35 (s, 3H), 3.58 (m, 1H), 3.63 (br s,
2H), 4.27 (s, 2H), 4.76 (br s, 2H), 4.83 (s, 2H), 5.88 (s, 1H),
6.54 (s, 1H), 6.87 (s, 1H), 7.24–7.47 (m, 5H), 10.78 (s, 1H). 13
C
NMR (126 MHz, CDCl3) δ 13.4, 23.7, 32.8, 42.5, 49.7, 53.4,
55.6, 59.2, 71.8, 96.3, 100.0, 104.8, 125.5, 127.9, 129.4, 136.1,
149.8, 151.9, 159.4, 164.5, 170.8. HRMS (ESI) calculated for
C25H33N6O3S [M + H]+ 497.2335, found: 497.2338.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-((2,4-dichlorophenethyl)-
amino)-7-(2-methoxyethyl)-2-(methylthio)-7H-pyrrolo[2,3-d]pyri-
midine-6-carboxamide·TFA (14c). 1H NMR (500 MHz, CDCl3)
δ 2.60 (s, 3H), 2.94 (br s, 2H), 3.33 (m, 5H), 3.63 (br s, 2H),
4.23 (s, 2H), 4.74 (br s, 2H), 4.82 (s, 2H), 6.53 (s, 1H), 6.60 (s,
1H), 7.05 (s, 1H), 7.14–7.34 (m, 8H), 10.88 (s, 1H). 13C NMR
(126 MHz, CDCl3) δ 13.5, 31.9, 42.6, 43.4, 49.4, 53.5, 59.2,
71.7, 96.5, 100.0, 104.2, 125.6, 127.5, 128.1, 129.3, 129.5,
132.1, 133.4, 133.7, 134.5, 135.4, 149.9, 152.4, 159.3, 164.3,
172.2. HRMS (ESI) calculated for C28H31Cl2N6O3S [M + H]+
601.1555, found: 601.1557.
General procedure 1 for the synthesis of dimeric peptoids
(5). Rink amide MBHA resin (100 mg, 75 μmol) was swollen
with DMF (2 mL) in a 5 mL fritted syringe for 2 h. The Fmoc
protecting group on the resin was removed by treating with 20%
piperidine in DMF (2 × 10 min). Two peptoid residues were
added by a standard submonomer route23 using a microwave-
assisted protocol.24 Briefly, to the resin was added 1.5 mL of 2
M bromoacetic acid in DMF and 1.5 mL of 2 M diisopropylcar-
bodiimide (DIC) in DMF. The reaction mixture was subjected to
microwave irradiation at 10% power (2 × 15 seconds). The beads
were shaken manually for 10 seconds between microwave pulses
for proper mixing. At the end of the reaction, the reaction
mixture was drained, and the resins were washed with DMF (3 ×
2 mL), CH2Cl2 (2 × 2 mL), MeOH (2 × 2 mL), and DMF (3 ×
2 mL). To the resin was added 2 mL of an amine (2M in DMF),
and the same microwave reaction was carried out. This process
was repeated to prepare dimeric peptoids.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-(dimethylamino)-7-(2-
methoxyethyl)-2-(methylthio)-7H-pyrrolo[2,3-d]pyrimidine-6-
carboxamide·TFA (14d). 1H NMR (500 MHz, CDCl3) δ 2.56
(s, 3H), 3.07 (s, 6H), 3.28 (s, 3H), 3.60 (br s, 2H), 4.25 (s, 2H),
4.72 (br s, 2H), 4.81 (s, 2H), 6.00 (s, 1H), 6.47 (s, 1H), 7.11 (s,
1H), 7.25–7.42 (m, 5H). 13C NMR (126 MHz, CDCl3) δ 14.2,
39.7, 42.7, 49.7, 53.5, 59.1, 71.9, 98.7, 100.0, 104.8, 125.8,
127.9, 129.3, 136.4, 149.1, 155.5, 163.2, 165.1, 172.0. HRMS
(ESI) calculated for C22H29N6O3S [M + H]+ 457.2022, found:
457.2019.
General procedure 2 for the synthesis of 4,6,7-trisubstituted 2-
(methylthio)-7H-pyrrolo[2,3-d]pyrimidines (14). The peptoid-
loaded resin (5) was treated with 4,6-dichloro-2-methylthio-5-
formylaldehyde (6) (5 equiv.) and DIEA (5 equiv.) in THF at
room temperature overnight. The reaction mixture was drained
and washed with DMF (3 × 2 mL), CH2Cl2 (2 × 2 mL), MeOH
(2 × 2 mL), and DMF (3 × 2 mL). To a suspension of the resin-
bound aldehyde (7) in DIEA (20 equiv.) and NMP (1 mL) was
added an amine (20 equiv.). The mixture was shaken at 60 °C
overnight. After thorough washing, to the resin was added a sol-
ution of NaOMe (25 wt% in MeOH, 20 equiv.) in DMF (1 mL).
The mixture was agitated at room temperature overnight. The
resin was filtered and thoroughly washed with DMF (3 × 2 mL),
CH2Cl2 (2 × 2 mL), MeOH (2 × 2 mL), and DMF (3 × 2 mL).
After cleavage from the resin with a cleavage cocktail (95%
TFA, 2.5% TIPS, and 2.5% water) for 2 h at room temperature,
the crude products (14) were analysed by LC/MS. For further
characterization, the products were purified by HPLC.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-((3,4-dimethoxybenzyl)-
amino)-7-(2-methoxyethyl)-2-(methylthio)-7H-pyrrolo[2,3-d]pyri-
midine-6-carboxamide·TFA (14e). 1H NMR (500 MHz, CDCl3)
δ 0.78 (br s, 6H), 2.00 (m, 1H), 2.54 (s, 3H), 3.69 (s, 3H), 3.76
(s, 3H), 4.00 (s, 2H), 4.19 (d, J = 6.5 Hz, 2H), 4.38 (s, 2H), 4.66
(s, 2H), 5.83 (s, 1H), 5.97 (s, 1H), 6.33 (s, 1H), 6.49 (s, 1H),
6.59 (s, 1H), 6.69 (s, 1H), 7.11–7.36 (m, 5H), 11.42 (s, 1H). 13
C
NMR (126 MHz, CDCl3) δ 13.5, 20.0, 29.8, 46.7, 48.3, 50.5,
54.3, 55.9, 56.0, 96.0, 100.0, 105.6, 109.9, 111.0, 118.6, 126.5,
128.3, 129.2, 135.6, 148.6, 149.4, 150.5, 153.0, 158.7, 163.8,
170.5, 172.9. HRMS (ESI) calculated for C30H37N6O4S
[M + H]+ 577.2597, found: 577.2599.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-((2,2-diphenylethyl)-
amino)-7-(2-methoxyethyl)-2-(methylthio)-7H-pyrrolo[2,3-d]pyri-
midine-6-carboxamide·TFA (14f). 1H NMR (500 MHz, CDCl3)
δ 0.87 (d, J = 6.5 Hz, 6H), 2.10 (m, 1H), 2.58 (s, 3H), 3.88 (br
s, 2H), 4.10 (s, 2H), 4.28 (d, J = 7.5 Hz, 2H), 4.33 (br s, 1H),
4.80 (s, 2H), 6.05–6.13 (m, 2H), 6.70 (s, 1H), 7.05–7.30 (m,
15H), 10.70 (s, 1H). 13C NMR (126 MHz, CDCl3) δ 12.3, 18.1,
27.8, 28.0, 46.7, 48.0, 48.6, 52.4, 94.3, 98.1, 102.6, 124.2,
125.3, 126.0, 126.5, 126.9, 127.4, 133.6, 138.7, 150.4, 156.7,
162.2, 168.8. HRMS (ESI) calculated for C35H39N6O2S
[M + H]+ 607.2855, found: 607.2863.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-(isobutylamino)-7-(2-meth-
oxyethyl)-2-(methylthio)-7H-pyrrolo[2,3-d]pyrimidine-6-carbox-
amide·TFA (14a). 1H-NMR (500 MHz, CDCl3) δ 0.68 (d, J =
6.0 Hz, 6H), 1.73 (m, 1H), 2.53 (s, 3H), 2.80 (br s, 2H), 3.28 (s,
3H), 3.57 (br s, 2H), 4.18 (s, 2H), 4.68(br s, 2H), 4,75 (s, 2H),
5,84 (s, 1H), 6.46 (s, 1H), 6.80 (s, 1H), 7.17–7.40 (m, 5H),
10.97 (s, 1H). 13C-NMR (126 MHz, CDCl3) δ 13.4, 19.9, 27.9,
42.5, 49.5, 51.5, 53.4, 59.2, 71.7, 96.4, 100.0, 104.3, 125.6,
128.3, 129.5, 135.8, 149.9, 152.6, 159.3, 164.4, 170.8. HRMS
4232 | Org. Biomol. Chem., 2012, 10, 4229–4235
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+
H]+ 546.2829, found:
N-(2-Amino-2-oxoethyl)-N-benzyl-4-((4-hydroxyphenethyl)-
amino)-7-(2-methoxyethyl)-2-(methylthio)-7H-pyrrolo[2,3-d]pyri-
midine-6-carboxamide·TFA (14g). 1H NMR (500 MHz, CDCl3)
δ 0.85 (br s, 6H), 2.09 (m, 1H), 2.58 (s, 3H), 2.74 (br s, 2H),
3.34 (br s, 1H), 3.59 (br s, 1H), 4.12 (s, 2H), 4.25 (d, J = 6.5
Hz, 2H), 4.79 (s, 2H), 5.99 (s, 1H), 6.34 (s, 1H), 6.69–6.86 (s,
4H), 7.16 (s, 1H), 7.20–7.30 (m, 5H), 10.55 (s, 1H). 13C NMR
(126 MHz, CDCl3) δ 8.54, 14.2, 20.0, 29.7, 29.9, 34.6, 45.8,
49.7, 98.9, 100.0, 101.4, 115.7, 125.5, 128.0, 129.0, 129.8,
136.0, 152.6, 155.3, 156.4, 165.3, 166.1, 170.9. HRMS (ESI)
calculated for C29H35N6O3S [M + H]+ 547.2491, found:
547.2480.
calculated for C29H36N7O4 [M
546.2830.
N-(2-Amino-2-oxoethyl)-N-benzyl-2-((cyclohexylmethyl)-
amino)-4-(isobutylamino)-7-(2-methoxyethyl)-7H-pyrrolo[2,3-d]-
pyrimidine-6-carboxamide·TFA (15-3C). 1H-NMR (500 MHz,
CDCl3) δ 0.79 (s, 6H), 0.99 (m, 2H), 1.23 (m, 4H), 1.57 (m,
1H), 1.65 (m, 1H), 1.73 (m, 4H), 2.79 (s, 2H), 3.25 (t, J = 6.5
Hz, 2H), 3.30 (s, 3H), 3.58 (t, J = 4.5 Hz, 2H), 4.21 (s, 2H),
4.60 (t, J = 4.0 Hz, 2H), 4.80 (s, 2H), 6.36–6.44 (m, 3H), 7.06
(s, 1H), 7.25–7.47 (m, 5H), 9.05 (s, 1H). 13C-NMR (126 MHz,
CDCl3) δ 19.8, 25.8, 26.4, 28.4, 30.8, 37.9, 42.0, 47.3, 49.4,
51.3, 53.7, 59.2, 71.9, 92.3, 104.2, 125.6, 127.4, 128.1, 129.4,
135.9, 151.6, 151.8, 153.4, 164.9, 172.4. HRMS (ESI) calcu-
lated for C30H44N7O3 [M + H]+ 550.3505, found: 550.3508.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-((4-sulfamoylphenethyl)-
amino)-7-(2-methoxyethyl)-2-(methylthio)-7H-pyrrolo[2,3-d]pyri-
midine-6-carboxamide·TFA (14h). 1H NMR (500 MHz, CDCl3)
δ 0.79 (br s, 6H), 2.03 (m, 1H), 2.54 (s, 3H), 2.82 (br s, 2H),
3.40 (br s, 2H), 4.10 (s, 2H), 4.18 (d, J = 7.0 Hz, 2H), 4.75 (s,
2H), 5.11 (br s, 2H), 6.13 (s, 1H), 6.26 (s, 1H), 6.39 (s, 1H),
7.15–7.33 (m, 7H), 7.70 (d, J = 7.0 Hz, 2H), 10.56 (s, 1H). 13C
NMR (126 MHz, CDCl3) δ 9.2, 14.2, 20.0, 29.7, 30.0, 35.2,
45.8, 49.7, 99.0, 100.0, 101.5, 125.5, 126.3, 128.0, 128.9,
129.6, 136.0, 140.4, 144.5, 152.3, 156.2, 165.2, 166.2, 171.3.
HRMS (ESI) calculated for C29H36N7O4S2 [M + H]+ 610.2270,
found: 610.2279.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-(cyclopentylamino)-2-((2,4-
dichlorophenethyl)amino)-7-(2-methoxyethyl)-7H-pyrrolo[2,3-d]-
pyrimidine-6-carboxamide·TFA (15-4D). 1H-NMR (500 MHz,
CDCl3) δ 1.34 (m, 2H), 1.43 (m, 4H), 1.63 (m, 2H), 3.01 (t, J =
6.5 Hz, 2H), 3.31 (s, 3H), 3.52 (m, 3H), 3.65 (d, J = 6.5 Hz,
2H), 4.24 (s, 2H), 4.60 (br s, 2H), 4.80 (s, 2H), 6.38 (s, 1H),
6.45 (m, 2H), 7.16 (s, 1H), 7.19–7.43 (m, 8H), 8.95 (s, 1H).
13C-NMR (126 MHz, CDCl3) δ 23.7, 29.7, 33.0, 33.1, 40.6,
42.0, 49.7, 53.5, 55.2, 59.2, 72.1, 92.4, 104.6, 125.5, 127.4,
127.9, 129.4, 132.0, 133.2, 134.7, 134.8, 136.2, 151.1, 151.4,
153.0, 164.9, 172.0. HRMS (ESI) calculated for C32H38Cl2N7O3
[M + H]+ 638.2413, found: 638.2400.
General procedure 3 for the synthesis of 2,4,6,7-tetrasubsti-
tuted 7H-pyrrolo[2,3-d]pyrimidines (15). The resin-bound 4,6,7-
trisubstituted 2-(methylthio)-7H-pyrrolo[2,3-d]pyrimidines (12)
were treated with m-CPBA (10 equiv.) and NaHCO3 (15 equiv.)
in THF (2 mL)/H2O (400 μL) at room temperature for 2 h. After
washing, to the resin was added a solution of an amine (20
equiv.) and DIEA (100 equiv.) in NMP, and the mixture was
shaken at 170 °C overnight. The resin was filtered and washed
with DMF (3 × 2 mL), CH2Cl2 (2 × 2 mL), MeOH (2 × 2 mL),
and CH2Cl2 (3 × 2 mL). After cleavage from the resin followed
by evaporation, the products (15) were analysed by LC/MS. For
further characterization, the products were purified by HPLC.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-((3,4-dimethoxybenzyl)-
amino)-2-((2,2-diphenylethyl)amino)-7-(2-methoxyethyl)-7H-
pyrrolo[2,3-d]pyrimidine-6-carboxamide·TFA (15-5E). 1H-NMR
(500 MHz, CDCl3) δ 3.30 (s, 3H), 3.66 (s, 2H), 3.78 (s, 3H),
3.80 (s, 3H), 4.03 (s, 3H), 4.14 (s, 2H), 4.20 (m, 2H), 4.33 (s,
1H), 4.60 (s, 2H), 4.73 (s, 2H), 6.26 (br s, 1H), 6.38 (s, 1H),
6.45 (s, 1H), 6.55 (s, 1H), 6.65 (s, 1H), 6.76 (br s, 1H), 6.95 (s,
1H), 7.19–7.49 (m, 15H), 9.54 (s, 1H). 13C-NMR (126 MHz,
CDCl3) δ 42.4, 45.9, 47.1, 49.5, 50.5, 53.8, 56.1, 59.4, 72.0,
92.8, 104.7, 110.2, 111.3, 119.0, 126.3, 127.1, 128.0, 129.5,
136.1, 141.7, 149.0, 149.7, 151.5, 152.3, 153.5, 164.8, 172.1.
HRMS (ESI) calculated for C42H46N7O5 [M + H]+ 728.3560,
found: 728.3555.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-(ethylamino)-7-(2-methoxy-
ethyl)-2-((2-methoxyethyl)amino)-7H-pyrrolo[2,3-d]pyrimidine-
6-carboxamide·TFA (15-1A). 1H-NMR (500 MHz, CDCl3) δ
0.87 (br s, 3H), 2.95 (s, 2H), 3.25 (s, 3H), 3.30 (s, 3H),
3.44–3.54 (m, 6H), 4.17 (s, 2H), 4.54 (s, 2H), 4.74 (s, 2H), 5.75
(s, 1H), 6.30 (s, 1H), 6.39 (s, 1H), 6.83 (s, 1H), 7.24–7.44 (m,
5H), 9.27 (s, 1H). 13C-NMR (126 MHz, CDCl3) δ 13.9, 38.4,
40.8, 42.0, 49.9, 53.7, 59.1, 70.3, 71.9, 92.4, 104.5, 125.6,
127.9, 129.3, 136.3, 151.5, 151.8, 153.1, 164.8, 171.2. HRMS
(ESI) calculated for C24H34N7O4 [M + H]+ 484.2672, found:
484.2674.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-((2,4-dichlorophenethyl)-
amino)-2-((4-hydroxyphenethyl)amino)-7-(2-methoxyethyl)-7H-
pyrrolo[2,3-d]pyrimidine-6-carboxamide·TFA (15-6F). 1H-NMR
(500 MHz, CDCl3) δ 2.80 (t, J = 7.5 Hz, 2H), 2.85 (br s, 2H),
3.28 (m, 5H), 3.55 (m, 4H), 4.18 (s, 2H), 4.57 (s, 2H), 4.77 (s,
2H), 6.31 (s, 1H), 6.37 (s, 1H) 6.42 (s, 1H), 6.73 (d, J = 8.5 Hz,
2H), 7.06 (m, 3H), 7.15 (s, 1H), 7.19–7.35 (m, 7H), 9.12 (s,
1H). 13C-NMR (126 MHz, CDCl3) δ 32.2, 34.5, 42.1, 43.1,
49.3, 53.6, 59.3, 71.9, 92.6, 115.5, 125.6, 127.5, 128.0, 129.3,
129.6, 129.9, 130.5, 132.1, 133.4, 133.7, 134.5, 135.8, 151.2,
151.7, 153.3, 154.6, 164.8, 171.9. HRMS (ESI) calculated for
C35H38Cl2N7O4 [M + H]+ 690.2362, found: 690.2345.
N-(2-Amino-2-oxoethyl)-N-benzyl-2-(benzylamino)-7-(2-methoxy-
ethyl)-4-((2-methoxyethyl)amino)-7H-pyrrolo[2,3-d]pyrimidine-
6-carboxamide·TFA (15-2B). 1H-NMR (500 MHz, CDCl3) δ
3.18–3.27 (m, 10H), 3.46 (s, 2H), 4.22 (s, 2H), 4.57 (s, 2H),
4.60 (s, 2H), 4.79 (s, 2H), 5.81 (s, 1H), 6.29 (s, 1H), 6.79 (s,
N-(2-Amino-2-oxoethyl)-N-benzyl-2-(isobutylamino)-7-(2-meth-
oxyethyl)-4-((naphthalen-2-ylmethyl)amino)-7H-pyrrolo[2,3-d]-
pyrimidine-6-carboxamide·TFA (15-7G). 1H-NMR (500 MHz,
methanol-d4) δ 0.81 (br s, 6H), 1.81 (m, 1H), 3.27 (m, 5H), 3.71
(br s, 2H), 4.08 (s, 2H), 4.46 (s, 2H), 4.74 (s, 2H), 5.22 (s, 2H),
3
1H), 7.98 (s, 1H), 7.11–7.34 (m, 10H), 9.06 (s, 1H). C-NMR
(126 MHz, CDCl3) δ 35.6, 42.3, 43.7, 45.0,, 49.8, 53.8, 59.2,
69.9, 71.9, 92.9, 104.8, 126.0, 127.6, 128.1, 128.6, 129.4,
136.5, 138.4, 151.5, 152.5, 153.2, 164.9, 171.6. HRMS (ESI)
This journal is © The Royal Society of Chemistry 2012
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6.96 (s, 1H), 7.29–7.54 (m, 9H), 7.86–8.09 (m, 3H). 13C-NMR
(126 MHz, CDCl3) δ 20.3, 28.6, 29.9, 42.3, 45.2, 48.8, 53.7,
59.3, 71.8, 92.5, 100.7, 104.2, 122.3, 125.5, 126.1, 126.4,
127.3, 128.2, 129.3, 130.3, 134.0, 135.3, 136.4, 151.9, 153.0,
153.5, 164.6, 172.0. HRMS (ESI) calculated for C34H40N7O3
[M + H]+ 594.3192, found: 594.3189.
(500 MHz, CDCl3) δ 0.76 (s, 6H), 1.76 (s, 1H), 1.86 (m, 2H),
2.05 (m, 2H), 2.41 (m, 2H), 2.82 (s, 2H), 3.33 (s, 3H), 3.37 (t, J
= 7.0 Hz, 2H), 3.43 (m, 4H), 3.59 (s, 2H), 4.22 (s, 2H), 4.62 (s,
2H), 4.82 (s, 2H), 5.69 (s, 1H), 6.40 (s, 1H), 6.76 (2, 1H), 6.91
(s, 1H), 7.25–7.44 (m, 5H), 9.00 (s, 1H). 13C-NMR (126 MHz,
CDCl3) δ 17.9, 19.8, 26.9, 28.0, 30.9, 38.8, 40.4, 42.0, 47.3,
49.6, 51.1, 53.4, 59.1, 71.9, 92.4, 104.0, 125.6, 128.0, 129.4,
136.1, 151.3, 153.5, 164.7, 170.8, 175.5. HRMS (ESI) calcu-
lated for C30H43N8O4 [M + H]+ 579.3407, found: 579.3401.
N-(2-amino-2-oxoethyl)-N-benzyl-4-((2,2-diphenylethyl)amino)-
7-(2-methoxyethyl)-2-(piperidin-1-yl)-7H-pyrrolo[2,3-d]pyrimi-
dine-6-carboxamide·TFA (15-12H). 1H NMR (500 MHz,
CDCl3) δ 1.62 (s, 6H), 3.33 (s, 3H), 3.58 (s, 2H), 3.64 (s, 4H),
3.73 (s, 2H), 4.18 (s, 2H), 4.31, (s, 1H), 4.56 (t, J = 4.5 Hz, 2H),
4.77 (s, 2H), 5.63 (s, 1H), 6.46 (s, 1H), 6.88 (s, 1H), 7.07–7.30
(m, 15H), 9.72 (s, 1H). 13C NMR (126 MHz, CDCl3) δ 24.1,
25.3, 41.9, 46.8, 48.4, 49.4, 49.7, 53.5, 59.2, 71.7, 92.1, 103.4,
125.5, 127.1, 128.0, 128.4, 128.8, 129.2, 135.7, 140.7, 150.5,
152.2, 153.0, 164.8, 170.7. HRMS (ESI) calculated for
C40H46N7O3 [M + H]+ 646.3506, found: 646.3508.
Acknowledgements
We thank Mr Byungkee Sohn (POSTECH) for collecting NMR
data. This work was supported by the POSTECH Basic Science
Research Institute Grant and IU Simon Cancer Centre EDT
Program.
N-(2-Amino-2-oxoethyl)-N-benzyl-7-(2-methoxyethyl)-2-
((naphthalen-1-ylmethyl)amino)-4-((3-(2-oxopyrrolidin-1-yl)-
propyl)amino)-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide·TFA
(15-9I). 1H-NMR (500 MHz, methanol-d4) δ 1.86 (m, 4H), 2.23
(m, 2H), 2.99–3.27 (m, 6H), 3.40 (s, 3H), 3.71 (s, 2H), 4.04 (s,
2H), 4.41 (s, 2H), 4.71 (br s, 2H), 5.12 (s, 2H), 6.86 (s, 1H),
7.29–7.54 (m, 9H), 7.79 (d, J = 8.5 Hz, 1H), 7.87 (d, J = 7.5
Hz, 1H), 8.11 (d, J = 8.5 Hz, 1H). 13C-NMR (126 MHz, CDCl3)
δ 14.3, 17.7, 22.8, 29.8, 30.9, 40.3, 42.3, 42.9, 47.8, 55.3, 58.9,
71.0, 92.8, 100.0, 106.3, 123.3, 125.3, 125.4, 125.9, 126.6,
128.5, 129.0, 130.1, 131.4, 133.9, 151.1, 151.9, 153.1, 164.7,
172.1, 176.9. HRMS (ESI) calculated for C37H43N8O4 [M + H]+
663.3407, found: 663.3399.
Notes and references
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N-(2-Amino-2-oxoethyl)-N-benzyl-4-(ethylamino)-7-(2-methoxy-
ethyl)-2-((4-sulfamoylphenethyl)amino)-7H-pyrrolo[2,3-d]pyri-
midine-6-carboxamide·TFA (15-10A). 1H-NMR (500 MHz,
CDCl3) δ 0.96 (m, 3H), 2.98 (t, J = 6.5 Hz, 2H), 3.04 (s, 2H),
3.32 (s, 3H), 3.54 (s, 2H), 3.70 (m, 2H), 4.25 (s, 2H), 4.52 (s,
2H), 4.81 (s, 2H), 5.00 (br s, NH2), 6.09 (s, 1H), 6.36 (s, 1H),
6.70 (s, 1H), 6.92 (s, 1H), 7.24–7.47 (m, 7H), 7.81 (d, J = 8.5
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[M + H]+ 609.2607, found: 609.2602.
N-(2-Amino-2-oxoethyl)-N-benzyl-7-(2-methoxyethyl)-4-((2-
methoxyethyl)amino)-2-morpholino-7H-pyrrolo[2,3-d]pyrimi-
dine-6-carboxamide·TFA (15-11B). 1H-NMR (500 MHz,
CDCl3) δ 3.25 (m, 5H), 3.35 (m, 5H), 3.61 (s, 2H), 3.77–3.81
(m, 8H), 4.26 (s, 2H), 4.63 (s, 2H), 4.83 (s, 2H), 5.87 (s, 1H),
6.50 (s, 1H), 6.89 (s, 1H), 7.26–7.46 (m, 5H), 9.89 (s, 1H).
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53.5, 58.9, 59.1, 66.2, 29.6, 71.7, 92.8, 104.8, 125.8, 127.9,
128.9, 129.3, 136.3, 150.9, 152.4, 152.6, 164.7, 171.0. HRMS
(ESI) calculated for C26H36N7O5 [M + H]+ 526.2778, found:
526.2776.
N-(2-Amino-2-oxoethyl)-N-benzyl-4-(isobutylamino)-7-(2-meth-
oxyethyl)-2-((3-(2-oxopyrrolidin-1-yl)propyl)amino)-7H-pyrrolo-
[2,3-d]pyrimidine-6-carboxamide·TFA
(15-8C). 1H-NMR
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4234 | Org. Biomol. Chem., 2012, 10, 4229–4235
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