A novel and efficient synthesis of anti-cancer agent, mereletinib

Article abstract of DOI:10.3184/174751915X14320297505570

A convenient route for the synthesis of a third-generation epidermal growth factor receptor inhibitor, mereletinib (AZD9291) using starting materials that are commercially available has been achieved through reactions that are readily conducted under mild conditions. Importantly, a 5 g scale synthesis was also accomplished and this method could therefore be useful in the synthesis of similar drugs.

Full text of DOI:10.3184/174751915X14320297505570

318 RESEARCH PAPER
VOL. 39 JUNE, 318–320
JOURNAL OF CHEMICAL RESEARCH 2015
A novel and efficient synthesis of anti-cancer agent, mereletinib
ac
b
b
b
b
d
a,c*
Haidong Liu , Yongfeng Lv , Yuan Li , Jin Cai , Junqing Chen , Yu Qin and Min Ji
a
b
School of Biological Science & Medical Engineering, Southeast University, and School of Chemistry & Chemical Engineering, Southeast University Si Pai Lou
2
#, Nanjing City 210096, P.R. China
c
Suzhou Key Laboratory of Biomaterials and Technologies & Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou, 215123, P.R. China
Chia Tai Tianqing Pharmaceutical Group Co. Ltd., Nanjing, 210096, P.R. China
d
A convenient route for the synthesis of a third-generation epidermal growth factor receptor inhibitor, mereletinib (AZD9291) using
starting materials that are commercially available has been achieved through reactions that are readily conducted under mild conditions.
Importantly, a 5 g scale synthesis was also accomplished and this method could therefore be useful in the synthesis of similar drugs.
Keywords: irreversible inhibitor, non-small-cell lung cancer, AZD9291, epidermal growth factor receptor, mereletinib, 3-(pyrimidin-4-yl)indole
In the clinic, patients suffering from non-small-cell lung cancer
NSCLC) with activating mutations have been treated with
epidermal growth factor receptor (EGFR) inhibitors for many
years. As reversible small-molecule ATP analogues, the
first-generation gefitinib and the second-generation erlotinib
We now describe the development of a novel, highly efficient
method for the preparation of AZD9291 1 starting from readily
available starting materials.
(
1-6
7-10
Results and discussion
(
(
(
Fig. 1) were originally designed to inhibit the tyrosine kinase
TK) activity of wild-type EGFR. Both of these TK inhibitors
TKI) were found to be most effective in patients with advanced
Our plan for the synthesis of 1 is shown in Scheme 1.
Retrosynthetically, 1 can be broken into two fragments,
3-(2-chloro-pyrimidin-4-yl)-1-methyl-1H-indole
2 and the
NSCLC during their clinical development. However, both are
associated with side effects such as skin rash and diarrhoea
that are due to the inhibition of wild-type EGFR in skin and
gastrointestinal organs. Mereletinib (AZD9291) (Fig. 1) is a
novel oral, potent and selective third-generation irreversible
inhibitor of both EGFR-sensitising (EGFRm+) and T790M-
resistance mutations with selectivity over the wild type form
trisubstituted N-aryl-acrylamide 3. We synthesised fragment 2
11,14
by the reported method, so the focus was on establishing an
efficient method to prepare the trisubstituted N-aryl-acrylamide
3. Our synthesis of 3 began with reduction of the nitro group
of the commercially available 4-fluoro-2-methoxy-1-nitro-
benzene 4 to yield an amine, nitration of which gave 5 in 93%
yield (Scheme 2). We found that N1,N1,N2-trimethylethane-
1,2-diamine failed to react with the amine 5 under the reported
11-13
of the receptor.
This mono-anilino–pyrimidine compound
11
is structurally distinct from other third-generation EGFR TKIs
and offers a pharmacologically differentiated profile from those
of an earlier generation. As a result FDA granted AZD9291
Breakthrough Therapy Designation last year.
reaction conditions. As is well known electron-donating
substituents decrease the reactivity of nucleophilic aromatic
15-17
substitution.
Since the Boc-protected amino group is a
moderate to weak electron-donating group compared with the
amino group, the amine 5 was Boc-protected with di-t-butyl
pyrocarbonate to give 6 in 98% yield. Gratifyingly, the reaction
of 6 with N1,N1,N2-trimethylethane-1,2-diamine under mild
conditions displaced the fluoro group to give 7 in quantitative
yield. Catalytic reduction of the intermediate 7 with hydrogen
over Pd/C gave a quantitative yield of the corresponding
amine, a light yellow compound, acylation of which with
acryloyl chloride gave the corresponding intermediate 8 in
The synthesis of mereletinib has been a challenging and costly
task due to the high temperature and inefficient, impractical
synthetic routes. There are two synthetic methods documented
for the synthesis of AZD9291. The first one uses acryloyl chloride
11
as the acrylating reagent and gave a low yield (32%). The
second requires a very high temperature and the reduction of a
nitro group by Fe/ammonium chloride which is environmentally
14
hazardous, and moreover is an inefficient process.
N
N
N
O
O
N
O
O
N
O
O
O
NH
O
N
N
N
N
N
HN
NH
O
HN
Cl
F
gefitinib
erlotinib
mereletinib
Fig 1.
N
N
N
N
O
N
N
O
NH
O
N
Cl
+
N
N
H
2
N
NH
N
NH
O
AZD9291 (1)
(2)
(3)
Scheme 1
*
Correspondent. E-mail: 101010516@seu.edu.cn

JOURNAL OF CHEMICAL RESEARCH 2015 319
1
)Pd/C, H , rt
O
F
2
(Boc) O
O
F
2
o
H
2
N
NO
2
DCM, 40 C
8%
O
2
N
2)H
2
SO
4
/HNO
3
9
9
3%
(4)
(5)
N
O
F
O
N
2
Pd/C, H , rt
HN
N
HN
Boc
NO
2
o
MeOH, 95%
DMA,60 C
HN
NO
2
99%
Boc
(7)
(6)
O
O
N
N
O
N
Cl
N
MeOH/HCl
HN
NH
H
2
N
NH
THF/H
2
O, 96%
95%
Boc
O
O
(8)
(3)
Scheme 2
excellent yield. The Boc-protected 5-amino group of 8 resisted
a Michael reaction due to its decreased nucleophilicity, and
so de-protection of the Boc-group of 8 with 2N HCl/MeOH
gave the desired salt of target compound 3 in 95% yield. In a
final step, the indolyl-2-pyrazoyl chloride 2 reacted with the
trisubstituted N-aryl-acrylamide 3 in butanol in the presence
of 4-methylbenzenesulfonic acid under very mild conditions
4-yl)-1-methylindole (5.08 g, 62%) as a white solid. m.p. 201°C dec.
1
(acetonitrile/water); H NMR (CDCl
) δ 8.45 (m, 2H), 8.35 (m, 1H),
+
3
7.37–7.95 (m, 4H), 3.89 (s, 3H); MS calcd for C H ClN [M] 243.1;
13 10
3
found: 244.1
-Fluoro-2-methoxy-5-nitro-phenylamine (5): 4-Fluoro-2-methoxy-
aniline (12.0g, 85.0 mmol) was added to cooled concentrated H SO
4
2
4
14
o
(
(
80 mL). The mixture was stirred at 0–10 C for 15–30 min. KNO3
8.6g, 85.0 mmol) was added to the mixture. The resulting mixture was
(40°C/2.5 h) and, conveniently, cooling the reaction mixture to
o
stirred at 0–5 C for 1–2 h and then poured into ice/water. The mixture
0
°C produced crystalline 3 (AZD9291) in 92% yield.
was neutralised with concentrated NH OH. The resulting solid was
4
To further evaluate the synthetic potential of this protocol,
filtered off and dried under vacuum. A suspension of crude product
and Pd/C (0.35g, 0.3%) in methanol (200 mL) was stirred under one
atm hydrogen at room temperature for 2–3 h. Filtration of the Pd/C
was effected through celite and the solid cake washed with methanol.
The combined solvents were evaporated under reduced pressure.
The corresponding amine was used in the next step without further
purification.
gram-scale reactions were performed under the optimized
reaction conditions. Gratifyingly, the reactions proceeded
smoothly to give the corresponding products in 90% isolated
yields. Because AZD9291 is a solid, it was isolated in high
yield without chromatography. The overall yield was 75%
from 3-(2-chloropyrimidin-4-yl)-1H-indole. Finally, there was
1
good agreement between the H NMR spectra at 400 MHz of
(4-Fluoro-2-methoxy-5-nitro-phenyl)-carbamic acid t-butyl ester
(6): A solution of 4-fluoro-2-methoxy-5-nitroaniline (8.0g, 43.0 mmol)
11,14
AZD9291 in CDCl and previously reported spectral data.
3
o
in DCM (dichloromethane) (100 mL) was cooled to 0–5 C in an ice/
Experimental
water bath. Boc O (9.4g, 43.0 mmol) in DCM (30 mL) was added to
2
the mixture slowly. The progress of the reaction was monitored by
TLC. After completion of the reaction, the reaction mixture was
concentrated to dryness under reduced pressure. The crude product
was purified by flash silica chromatography, with gradient 10−40%
EtOAc in hexane to yield intermediate (6) (12.0 g, 42.1 mmol, 98%)
All reagents including analytical-grade solvents were purchased from
Sigma–Aldrich (USA), Aladdin (China), or Sinopharm Chemical
Reagent (China) and used without further purification. Melting points
are uncorrected. NMR spectra were obtained on a Bruker 400 MHz
1
13
spectrometer ( H NMR at 400 Hz, C NMR at 100 Hz) in CDCl or
3
1
as a yellow solid. m.p. 88–90 °C (EtOAc /hexane); H NMR (CDCl )
DMSO-d using TMS as internal standard. Chemical shifts (δ) are
3
6
δ 8.91 (br, 1H), 6.99 (s, 1H), 6.72 (d, J=12.0, 1H), 4.0 (s, 3H), 1.567 (s,
given in ppm and coupling constants (J) in Hz. Mass spectra (MS)
were obtained from Finnigan (USA) MAT-95 Spectrometry Services.
The synthesised compounds were obtained as detailed below. Silica gel
1
3
9
1
1
H); C NMR (CDCl ) δ 153.5, 152.6, 152.5,152.2, 150.9, 124.7, 124.7,
3
14.7, 100.0, 99.7, 56.8, 28.3, 7.9; IR 3432, 2985, 1723, 1536, 1485,
158. MS calcd for C H FN O [M-H] 285.0887; found: 285.0865
-
(
200–300 µm) for flash chromatography was purchased from Qingdao
12 15 2 5
{
4-[(2-Dimethylamino-ethyl)-methyl-amino]-2-methoxy-5-nitro-
phenyl}-carbamic acid t-butyl ester (7): N1,N1,N2-Trimethylethane-
,2-diamine (2.7 g, 27.0 mmol) was added to a solution of (4-fluoro-2-
Haiyang Chemical (China).
Synthesis of 3-(2-Chloropyrimidin-4-yl)-1-methylindole (2)
1
11
This compound was prepared by the procedure of Finlay et al.
A
methoxy-5-nitro-phenyl)-carbamic acid t-butyl ester (6.3g, 22.0 mmol)
and DIPEA (N,N-Diisopropylethylamine) (3.82 mL, 22.0 mmol) in
DMA (N,N-Dimethylacetamide) (100 mL). The mixture was heated
to 60 °C and stirred at this temperature for 2h. Water (200 mL) was
added to the reaction mixture, which was then extracted with DCM
(50 mL*3). The combined extracts were dried over anhydrous
magnesium sulfate. The solvent was removed under vacuum to give
suspension of 2,4-dichloropyrimidine (5.0 g, 33.6 mmol) and aluminum
chloride (1.83 mL, 33.6 mmol) in DME (1,2-dimethoxyethane)
(50 mL) was stirred at ambient temperature for 15 min. To this was
added 1-methylindole (4.29 mL, 33.6 mmol), and the mixture was
heated at 80 °C for 2–4 h. The cooled reaction mixture was added
dropwise to vigorously stirring water (300 mL) over 20 min. Upon
complete addition, the mixture was stirred for 30 min, filtered
and the solid washed with water (250 mL). The crude product was
purified by flash silica chromatography, eluting with DCM. Pure
fractions were evaporated to dryness to afford 3-(2-chloropyrimidin-
1
7 as an orange solid (7.9 g, 97%); m.p. 92–94 °C (DCM). H NMR
(DMSO) δ 8.12 (m, 2H), 6.74 (s, 1H), 3.90 (s, 3H), 3.21 (m, 2H), 2.81
13
(s, 3H), 2.44 (m, 2H), 2.14 (s, 6H), 1.45 (s, 9H); C NMR (DMSO) δ
153.5, 144.9, 132.1, 120.0, 102.4, 79.8, 56.8, 56.7, 53.1, 45.9, 40.8, 40.6,

320 JOURNAL OF CHEMICAL RESEARCH 2015
4
0.4, 28.5, 27.9; IR 3441, 2979, 2359, 1708, 1546, 1162; MS calcd for
δ 10.19 (br, 1H), 9.88 (s, 1H), 9.13(s, 1H), 8.40(d, 1H), 8.08(t, 1H),
7.75(s, 1H), 7.42 (t, 1H), 7.27 (m, 1H), 6.81 (s, 1H), 6.47 (m, 1H), 5.73
(m, 2H), 4.02(s, 3H), 3.91(s, 3H) , 2.92(m, 2H) , 2.73(s, 3H) , 2.31(s,
+
C H N O [M+H] 369.2132; found: 369.2136. The crude product was
used in the next step without further purification.
N-{5-Amino-2-[(2-dimethylamino-ethyl)-methyl-amino]-4-
methoxy-phenyl}-acrylamide (3): Acryloyl chloride (20 mL, 1M
in THF, 20.0 mmol) was added dropwise to intermediate 7 (7.3 g,
1
7
28
4
5
+
8H); MS calcd for C H N O [M+H] 499.27; found: 500.3
2
8
33
7
2
We are grateful for financial support from the National
Basic Research Program of China (No. 2011CB933503 and
No.2013AA032205).
19.8 mmol) and DIPEA (3.82 mL, 22.0 mmol) in THF (100 mL)
cooled to 0 °C. The resulting mixture was stirred at 0 °C for 2 h. The
reaction mixture was extracted with DCM (100 mL*2) and the organic
extract was washed sequentially with saturated NaHCO (50 mL),
3
Received 16 April 2015; accepted 14 May 2015
Paper 1503316 doi: 10.3184/174751915X14320297505570
Published online: 4 June 2015
water (50 mL), and saturated brine (50 mL). The organic layer was
evaporated to afford the crude product which was purified by flash
silica chromatography, through the gradient elution 0–10% MeOH
in DCM to yield {5-acryloylamino-4-[(2-dimethylamino-ethyl)-
methyl-amino]-2-methoxy-phenyl}-carbamic acid t-butyl ester as a
brown oil. This was dissolved in cooled 3N/MeOH (100mL), and the
mixture stirred at room temperature for 20 h. The solvent was removed
References
1
K. Ohashi, Y. E. Maruvka, F. Michor and W. Pao, J. Clin. Oncol., 2013, 31,
070.
1
2
R.Rosell, E. Carcereny, C. Pallares and G. Altavilla, N. Engl. J. Med., 2010,
362, 2380.
and the residue neutralised with saturated NaHCO aqueous, and then
3
extracted with DCM. The crude product was purified by flash silica
chromatography, with gradient elution 0−10% MeOH in DCM to yield
3
4
5
S. Kobayashi, B. E. Johnson and B. Halmos, N. Engl. J. Med., 2005, 352, 786.
Ou, S.-H. I., Crit. Rev. Oncol. Hematol., 2012, 83, 407.
R. A. Ward, N. Colclough , C. Chuaqui and M. J. Waring, J. Med. Chem.,
1
the intermediate 3 (5.04g, 87%) as a brown oil. H NMR (CDCl ); δ
3
2
013, 56, 7025.
A. O. Walter, R. M. Labenski, Z. Zhu, and A. Allen, Cancer Discovery, 2013,
, 1404.
10.03 (br, 1H), 7.99 (s, 1H), 6.69 (s, 1H), 6.39 (m, 2H), 5.68 (m, 1H),
6
7
8
9
3
.83 (s, 3H), 3.78 (br, 2H), 2.89 (m, 2H), 2.67(s, 6H), 2.30(m, 2H);
3
13
C NMR (CDCl ); δ 163.3, 143.6, 133. 9, 132.4, 132.3, 129.9, 125.9,
3
M. Fukuoka, G. Giaccone, Y. Nishiwaki and J. Baselga, J. Clin. Oncol.,
2003, 12, 2237.
T. S. Mok, Y. Wu, S. Thongprasert and M. Fukuoka, N. Engl. J. Med., 2009,
107.1, 105.2, 57.2, 55.8, 45.15, 44.2; IR 3452, 3342, 2935, 2823, 1670,
+
1526, 1207; MS calcd for C H N O [M+H] 293.1972; found:
15
24
4
2
3
61, 947.
M. Tsao, A. Sakurada, I. Lorimer and F. A. Shepherd, N. Engl. J. Med., 2005,
, 133.
F. A. Shepherd, J. Rodrigues Pereira and L. Seymour, N. Engl. J. Med., 2005,
53, 123.
2
93.1973.
N-[2- (2-Dimethylaminoethylmethylamino) -4-methoxy-5-
[4-(1-methylindol-3-yl)pyrimidin-2-yl]amino]phenyl]prop-2-
enamide. (AZD9291): 4-Methylbenzenesulfonic acid hydrate (6.5 g,
4.2 mmol) was added in one portion to 3-(2-chloropyrimidin-4-yl)-1-
2
[
10
3
3
11
M. Raymond V. Finlay, M. Anderton, and G. L. Wrigley, J. Med. Chem.,
2014, 57, 8249.
methylindole 2 (4.2 g, 17.1 mmol) and intermediate 3 (5.0 g, 17.1 mmol)
in n-butanol (80 mL). The resulting mixture was stirred at 40 °C for
12 D. A. E. Cross, S. E. Ashton, M. R. Ranson and W. Pao, Cancer Discovery,
2014, 4, 1046.
o
2
.5 h. The mixture was cooled to 0–5 C and stirred at this temperature
13
S. Peters, S. Zimmermann and A. A. Adjei, Cancer Treatment Rev., 2014,
0, 917.
for 1–2h. The precipitate was collected by filtration, washed with
n-butanol (20 mL), and dried under vacuum to afford AZD9291 as
a yellow solid. The yellow solid was triturated with MeCN to give a
solid which was collected by filtration and dried under vacuum to give
4
14
S. Butterworth, M. R. V. Finlay and H. M. Redfearn, US20130053409A1.
15 C. F. Bernasconi, Chimia, 1980, 34, 1.
16 M. Makosza and K. Wojciechowski, Liebigs Annalen, 1997, 9, 1805.
17 O. Acevedo and W. L. Jorgensen, Org. Lett., 2004, 6, 2881.
1
AZD9291 (7.8 g,15.7 mmol, 92%) as a yellow solid. H NMR (CDCl )
3