Synthesis of [1,2]oxazolo[5,4-e]indazoles as antitumour agents

Article abstract of DOI:10.1016/j.tet.2013.05.083

A series of 40 derivatives of the [1,2]oxazolo[5,4-e]indazoles ring system have been prepared with good yields using a versatile and convenient route. Annelation of the [1,2]oxazole ring on the indazole-4-one system was achieved by reaction of the corresp

Full text of DOI:10.1016/j.tet.2013.05.083

Tetrahedron 69 (2013) 6474e6477
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Synthesis of [1,2]oxazolo[5,4-e]indazoles as antitumour agents
*
ꢀ
Paola Barraja , Virginia Spano, Daniele Giallombardo, Patrizia Diana,
Alessandra Montalbano, Anna Carbone, Barbara Parrino, Girolamo Cirrincione
Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche, Via Archirafi 32, 90123 Palermo, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of 40 derivatives of the [1,2]oxazolo[5,4-e]indazoles ring system have been prepared with good
yields using a versatile and convenient route. Annelation of the [1,2]oxazole ring on the indazole-4-one
system was achieved by reaction of the corresponding enaminoketones with hydroxylamine hydro-
chloride. Derivatives of the title ring system were tested by the National Cancer Institute of Bethesda and
one of them (13t) showed growth-inhibitor activity against all the 54 human tumour cell lines generally
at low micromolar concentrations.
Received 10 December 2012
Received in revised form 6 May 2013
Accepted 20 May 2013
Available online 29 May 2013
Keywords:
Lonidamine
Ó 2013 Elsevier Ltd. All rights reserved.
[1,2]Oxazolo[5,4-e]indazoles
Enaminoketones
Hydroxylamine hydrochloride
Antiproliferative activity
1. Introduction
tissue acting via inhibition of the energy metabolism, nowadays in
phase III clinical trials.4e6
Although scarcely found in nature, pyrazoles are known for
their wide range of pharmacological applications as herbicides,
antipsychotic, antibacterial, antimycotic and antiinfiammatory
agents.1e3 Benzocondensation to the pyrazole nucleus, leads to
indazole derivatives, which are reported to be endowed with re-
markable antitumour activity by different mechanisms. Leading
examples are Lonidamine 1 (LND) and analogues 2 and 3 (Chart 1).
LND is a potent antitumour drug, used in the treatment of several
neoplasia as breast, lung, kidney, bladder as well as sarcomas of soft
Moreover LND acts as a photosensitizer thus potentiating the
cytotoxic effect of UV light targeting mainly mitochondria and
membrane structures.7 The potent activity of LND, encouraged
through the years the synthesis of several analogues,8e11 and have
attracted our attention also because of our recent interest on
antitumour agents including those with photosensitizing proper-
ties,12e22 encouraging us the development of new molecules con-
taining the pyrazole core. We have recently turned our attention to
the incorporation of the [1,2]oxazole moiety on tricyclic systems
containing the pyrrole ring. In fact several examples of compounds
incorporating an [1,2]oxazole are reported as potent antitumour
agents.23,24 Thus, we synthesized the ring system [1,2]oxazolo[4,5-
g]indole 4, which demonstrated very promising antitumour prop-
erties when tested at the NCI of Bethesda on a panel of 60 human
tumour cell lines.25
R
2
N
O1
N
O
R
N
N
3
8
N
7
N
4
R1
N
R1
6
5
R1
In consideration of the potent antitumour activity of compounds
bearing the pyrazole and [1,2]oxazole moieties we planned the
synthesis of a series of [1,2]oxazolo[5,4-e]indazoles (5) with the
intent of investigating the effect of the simultaneous presence
in the tricyclic system of both the pyrazole and the [1,2]oxazole
systems.
R1
4
5
1 LND R = COOH R1=Cl
2 YD-3 R =
R1=H
R1=H
COOEt
3 YC-1 R =
CH2OH
O
Chart 1. Structures of LND (1), YD-3 (2), YC-1 (3), [1,2]oxazolo[4,5-g]indole (4), [1,2]
oxazolo[5,4-e]indazole (5).
2. Results and discussion
Our approach to the synthesis of the title ring system consisted
on the preparation of a number of tetrahydroindazole-4-ones of
* Corresponding author. Tel.: þ39 091 6161606; fax: þ39 091 23860854; e-mail
address: paola.barraja@unipa.it (P. Barraja).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.05.083

P. Barraja et al. / Tetrahedron 69 (2013) 6474e6477
6475
type 8 and 9, which could be further functionalized in
a
position to
and 10% Pd/C in reasonable yields (50e69%). From reaction of the
tosylhydrazone 7a, spontaneous elimination of toluenesulfonic
acid occurred and the NH indazoles 8aed were obtained. Inda-
zoles 8aed were then subjected to alkylation at the pyrrole ni-
trogen with benzylchlorides or bromides, in the presence of NaH
yielding the N(1)-substituted derivatives 9aey (10e83%). Among
these, the N(1)-benzyl and 4-methoxybenzyl derivatives 9aed, iel
were isolated as main components (65e83%) from mixtures with
their corresponding N(2) regioisomers 9eeh, mep (10e15%), be-
ing the N(1) isomers the most favoured of the two. Spectroscopic
data of 9eeh, mep are in agreement with the N(2) structure of
8eet.26
the carbonyl group with an enamino functionality to give com-
pounds 10 and 11, key synthons for the annelation of the [1,2]
oxazole moiety (Scheme 1). Tetrahydroindazol-4-ones 8aet were
conveniently prepared by reaction of the commercially available
cyclohexane-1,3-dione 6, with substituted hydrazines to give
achieve the corresponding hydrazones 7aed in very good yield
(74e96%).
O
O
Recently we have reported that the enamino functionality can
H
N
O
H2NHNR
i
be introduced in
a position to the annular carbonyl in tetrahy-
N
H
R
O
droindolone systems using tert-butoxybis(dimethylamino)meth-
ane (TBDMAM), in the case of poor reactive substrates,17e22 or
alternatively dimethylformamide dimethylacetal (DMFDMA), less
reactive but indeed available at low cost. Thus, tetrahydroindazol-
4-ones 8eet and 9aey were converted into the corresponding
enaminoketones 10eet and 11aey in DMFDMA under microwave
irradiation (PW 150, T 150 ꢀC) in 45e95% and 68e98% yields,
respectively.
Annelation of the [1,2]oxazole ring was accomplished by re-
action of enaminoketones 10,11 with hydroxylamine hydrochloride
as 1,3 dinucleophile, in refluxing ethanol and catalytic amount of
acetic acid. By this route 40 derivatives (12eet, 13aey) of the [1,2]
oxazolo[5,4-e]indazoles were generally obtained in good yields
(50e92%, Table 1).
7a-d
a R = Ts; b R = C6H5; c R = 4-OMe-C6H4; d R = 4-NO2-C6H4
OH
6
R1CHO
for 7a
-TsOH
ii
O
R1
O
R1
N2
when R=H
N
N
H
R
N
1
8a-d
8a-t
a-d (R = H): (a) R1 = C6H5, (b) R1 = 4-OMe-C6H4,
(c) R1 = 3,4-(OMe)2-C6H3, (d) R1 = 3,4,5-(OMe)3-C6H2;
e-h (R = C6H5): (e) R1 = C6H5, (f) R1 = 4-OMe-C6H4,
(g) R1 = 3,4-(OMe)2-C6H3, (h) R1 = 3,4,5-(OMe)3-C6H2;
i-l (R = 4-OMe-C6H4): (i) R1= C6H5, (j) R1 = 4-OMe-C6H4,
(k) R1 = 3,4-(OMe)2-C6H3, (l) R1 = 3,4,5-(OMe)3-C6H2;
m-p (R = 4-NO2-C6H4): (m) R1 = C6H5, (n) R1 = 4-OMe-C6H4,
(o) R1 = 3,4-(OMe)2-C6H3, (p) R1 = 3,4,5-(OMe)3-C6H2;
q-t (R = 4-NH2-C6H4): (q) R1 = C6H5, (r) R1 = 4-OMe-C6H4,
(s) R1 = 3,4-(OMe)2-C6H3, (t) R1 = 3,4,5-(OMe)3-C6H2
iv
O
Table 1
R1
N
[1,2]Oxazolo[5,4-e]indazoles 12, 13
R1
R
Yields (%)
N
R
iii
12e
12f
12g
12h
12i
12j
12k
12l
12m
12n
12o
12p
12q
12r
12s
12t
13a
13b
13c
13d
13e
13f
13g
13h
13i
13j
13k
13l
13m
13n
13o
13p
13q
13r
13s
13t
13u
13v
13x
13y
C6H5
C6H5
C6H5
C6H5
C6H5
56
70
78
74
86
72
90
92
62
68
50
50
58
60
70
72
72
86
84
56
68
58
50
65
80
64
60
72
63
76
68
54
50
54
58
54
70
70
72
66
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
9a-y
v
a-d (R = N(1)Bn): (a) R1 = C6H5, (b) R1 = 4-
OMe-C6H4, (c) R1 = 3,4-(OMe)2-C6H3, (d)
R1 = 3,4,5-(OMe)3-C6H2;
4-OMeeC6H4
4-OMeeC6H4
4-OMeeC6H4
4-OMeeC6H4
4-NO2eC6H4
4-NO2eC6H4
4-NO2eC6H4
4-NO2eC6H4
4-NH2eC6H4
4-NH2eC6H4
4-NH2eC6H4
4-NH2eC6H4
N(1)Bn
N(1)Bn
N(1)Bn
N(1)Bn
N(2)Bn
N(2)Bn
N(2)Bn
N(2)Bn
N(1)4-OMeeBn
N(1)4-OMeeBn
N(1)4-OMeeBn
N(1)4-OMeeBn
N(2)4-OMeeBn
N(2)4-OMeeBn
N(2)4-OMeeBn
N(2)4-OMeeBn
N(1)3,4-(OMe)2eBn
N(1)3,4-(OMe)2eBn
N(1)3,4-(OMe)2eBn
N(1)3,4-(OMe)2eBn
N(1)3,4,5-(OMe)3eBn
N(1)3,4,5-(OMe)3eBn
N(1)3,4,5-(OMe)3eBn
N(1)3,4,5-(OMe)3eBn
R1
N
O
e-h (R = N(2)Bn): (e) R1 = C6H5, (f) R1 = 4-
OMe-C6H4, (g) R1 = 3,4-(OMe)2-C6H3, (h)
R1= 3,4,5-(OMe)3-C6H2;
Me2N
v
N
i-l (R = N(1)4-OMe-Bn): (i) R1 = C6H5, (j) R1
= 4-OMe-C6H4, (k) R1 = 3,4-(OMe)2-C6H3,
(l) R1 = 3,4,5-(OMe)3-C6H2;
R
10e-t (from 8e-t),
11a-y (from 9a-y)
m-p (R = N(2)4-OMe-Bn): (m) R1 = C6H5,
(n) R1 = 4-OMe-C6H4, (o) R1 = 3,4-(OMe)2-
C6H3, (p) R1 = 3,4,5-(OMe)3-C6H2;
vi
q-t (R = N(1)3,4-(OMe)2-Bn): (q) R1 = C6H5,
(r) R1 = 4-OMe-C6H4, (s) R1 = 3,4-(OMe)2-
C6H3, (t) R1 = 3,4,5-(OMe)3-C6H2;
2
O1
R1
8
N
u-y (R = N(1)3,4,5-(OMe)3-Bn): (u) R1 =
C6H5, (v) R1 = 4-OMe-C6H4, (x) R1 = 3,4-
(OMe)2-C6H3, (y) R1 = 3,4,5-(OMe)3-C6H2
3
N
N
4
5
R
6
12e-t (from 10e-t),
13a-y (from 11a-y)
see Table 1
Scheme 1. Synthesis of [1,2]oxazolo[5,4-e]indazoles 12 and 13. Reagents: (i) 80%
AcOH/water (1:1) for 7a or water for 7bed, 0 ꢀC then rt 10 mine2 h, 74e96%; (ii) DMF,
AcOH, piperidine, 80e100 ꢀC, 50 mine3 h, 70e98%; (iii) EtOH, H2, 10% Pd/C, 50e69%,
rt, 24 h; (iv) benzylhalides, NaH, DMF, 0 ꢀC then rt or reflux, 1e24 h, 10e83%; (v)
DMFDMA, MW (PW 150, T 150 ꢀC), 15 mine2 h, 45e98%; (vi) NH2OH, MeOH/AcOH
(2:1), reflux, 50 min, 50e92%.
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
C6H5
4-OMeeC6H4
3,4-(OMe)2eC6H3
3,4,5-(OMe)3eC6H2
Benzaldehyde and its mono-, di- and tri-methoxy substituted
derivatives were reacted with 7aed in a mixture of dime-
thylformamide and acetic acid in the presence of catalytic amount
of piperidine to furnish the desired tetrahydroindazoles 8aep in
70e98% yields. The nitro derivatives 8mep were converted into
the corresponding amino derivatives 8qet by reduction with H2

6476
P. Barraja et al. / Tetrahedron 69 (2013) 6474e6477
The structure of all synthesized compounds were confirmed
4.2. General procedure for the synthesis of compounds 7aed
(7a as an example)
by spectroscopic data (IR, 1H and 13C NMR) and elemental analysis
(C, H, N) reported in the Supplementary data. [1,2]Oxazolo[5,4-e]
indazoles 12 and 13 were submitted at the NCI of Bethesda for the
in vitro antitumour screenings. Among these derivatives 12eel, qet
and 13aey were prescreened according to the NCI protocol at
the 10ꢁ5 M dose on the full panel of 60 human cancer cell
lines derived from nine human cancer cell types that have been
grouped in disease sub-panels including leukaemia, non-small-cell
lung, colon, central nervous system, melanoma, ovarian, renal,
prostate, and breast tumour cell lines. Disappointingly, only 6-(3,
4-dimethoxylbenzyl)-8-(3,4,5-trimethoxyphenyl)-5,6-dihydro-4H-
[1,2]oxazolo[5,4-e]indazole 13t, was selected for further screenings
at five concentrations at 10-fold dilution (10ꢁ4e10ꢁ8 M) on the full
panel reaching micromolar and submicromolar concentrations
To a solution of cyclohexane-1,3-dione 6 (2.8 g, 25 mmol) in 80%
AcOH/water (1:1) (100 mL) for 7a or water (100 mL) for 7bed (see
supplementary data), a solution of suitable hydrazine (25 mmol) in
water (70 mL) was added at 0 ꢀC and the reaction mixture was
stirred at rt. From the reaction mixture a solid was separated. Then
it was filtered off and dried.
4.2.1. 4-Methyl-N0-(3-oxocyclohex-1-en-1-yl)benzenesulfonohy-
drazide (7a). This compound was obtained by reaction with
tosylhydrazine after 10 min at rt according to a reported pro-
cedure.26 White solid; Rf¼0.15 (EtOAc); mp 205e206 ꢀC; yield 82%;
IR cmꢁ1: 3296 (NH), 3294 (NH), 1608 (CO). 1H NMR (DMSO-d6):
against all the 54 tested cell lines with a GI50 range of 0.11e58.1
and a pGI50 MG_MID value of 5.33 (see Table 2 in the supplementary
data). In particular the best selectivity was observed against the HL-
m
M
d
1.68e1.80 (2H, m, CH2), 2.05 (2H, t, J¼5.7 Hz, CH2), 2.21 (2H, t,
J¼5.7 Hz, CH2), 2.39 (3H, s, CH3), 5.14 (1H, s, CH), 7.42 (2H, d,
J¼8.2 Hz, H-30 and H-50), 7.70 (2H, d, J¼8.2 Hz, H-20 and H-60), 8.64
60(TB) cell line of the leukaemia sub-panel (0.11
mM) (Table 2). This
(1H, s, NH), 9.76 (1H, s, NH). 13C NMR (DMSO-d6):
d 21.0 (q), 21.4 (t),
latter subpanel together with the colon, the CNS and the breast
cancer sub-panels are those towards which 13t shows the best se-
25.3 (t), 36.5 (t), 98.0 (d), 127.5 (dꢃ2), 129.7 (dꢃ2), 135.6 (s), 143.5
(s), 143.6 (s), 195.4 (CO). Anal. Calcd for C13H16N2O3S (280.34): C,
55.70; H, 5.75; N, 9.99. Found: C, 55.91; H, 5.87; N, 9.75.
lectivity with GI50 ranges of 0.11e3.76
1.39e7.99 M and 1.94e8.00 M, respectively. Moreover with the
exception of the NCI-H322M cell line (GI50 58.1 M) of the Non-
Small Cell Lung cancer subpanel and the OVCAR-5 (GI50 26.6 M)
and OVCAR-8 cell lines (GI50 19.6 M) of the ovarian cancer, com-
pound 13t shows activity in the low micromolar range (GI50
3.17e6.85 M and 3.02e7.28 M) against the two sub-panels.
mM, 3.63e5.85 mM,
m
m
m
4.3. General procedure for the synthesis of compounds
(8aep)
m
m
To a solution of 7aed (7.14 mmol) in anhydrous DMF (8 mL), the
suitable benzaldehyde (7.14 mmol), AcOH (0.35 mL) and piperidine
(1.4 mL) were added. The reaction mixture was heated at
80e100 ꢀC. Then, it was poured onto crushed ice and the solid
collected and dried. For compounds 8bep see supplementary data.
m
m
3. Conclusions
In conclusion, we have set up a simple and versatile pathway for
the synthesis of new derivatives of the [1,2]oxazolo[5,4-e]indazole
ring system.
4.3.1. 3-Phenyl-1,5,6,7-tetrahydro-4H-indazol-4-one (8a). This com-
pound was obtained from the reaction of 7a with benzaldehyde after
1 h at 85 ꢀC. White solid; Rf¼0.20 (CH2Cl2/EtOAc 95:5); mp
187e188 ꢀC; yield 92%; IR cmꢁ1: 3210 (NH), 1649 (CO). 1H NMR
Variously substituted indazol-4-ones were prepared and
converted into the corresponding enaminoketones using
DMFDMA for the direct introduction of the enamino function-
ality, thus giving us the chance to investigate the reactivity
of pyrazole derivatives in comparison with our previous series
containing the pyrrole moiety. Preliminary results of the
in vitro studies at the NCI of Bethesda indicated the [1,2]oxazolo
[5,4-e]indazole 13t as a hit candidate of the series with in-
hibitory activity in the submicromolar and low micromolar
range encouraging further optimization from a structural point
of view.
(DMSO-d6):
d
1.99e2.12 (2H, m, CH2), 2.46 (2H, t, J¼6.1 Hz, CH2), 2.87
(2H, t, J¼6.1 Hz, CH2), 7.35e7.48 (3H, m, H-300, H-400 and H-500), 8.04
(2H, d, J¼7.5 Hz, H-200 and H-600), 13.38 (1H, s, NH). 13C NMR (DMSO-
d6):
d
21.6 (t), 23.0 (t), 39.2 (t), 113.9 (s), 114.0 (s), 127.9 (dꢃ2), 128.2
(dꢃ2), 128.5 (d), 131.5 (s) 153.8 (s), 192.7 (CO). Anal. Calcd for
C13H12N2O (212.25): C, 73.56; H, 5.70; N, 13.20. Found: C, 73.71; H,
5.53; N, 13.11. MS m/z 213 (MHþ). HRMS: [MH]þ, found 213.1058.
C13H12N2O requires 213.1022.
4. Experimental section
4.1. General
4.4. General procedure for the synthesis of compounds (8qet)
To a solution of 8mep (1.5 mmol) in ethanol, palladium 10% on
carbon was added and the reaction mixture was stirred under hy-
drogen atmosphere for 24 h. Then it was filtered and the filtrate was
dried under reduced pressure. The crude was purified by chroma-
tography column, using dichloromethane: ethyl acetate (9:1) as
eluent. For compounds 8ret see supplementary data.
All melting points were taken on a BuchieTottoli capillary
apparatus and were uncorrected; IR spectra were determined,
in CHBr3, with a Shimadzu FT/IR 8400S spectrophotometer; 1H
and 13C NMR spectra were measured in DMSO-d6 or CDCl3
solutions (TMS as internal reference), at 200 and 50.3 MHz, re-
spectively, using a Bruker Avance II series 200 MHz spectrometer.
Column chromatography was performed with Merck silica gel
230e400 Mesh ASTM or with a SEPACORE chromatography appa-
4.4.1. 2-(4-Aminophenyl)-3-phenyl-2,5,6,7-tetrahydro-4H-indazol-
4-one (8q). This compound was obtained from 8m. Yellow solꢁid1;
Rf¼0.14 (CH2Cl2/EtOAc 95:5); mp 207e208 ꢀC; yield 69%; IR cm
:
ratus BUCHI. Elemental analyses (C, H, N) were within ꢂ0.4% of the
3430e3346 (NH2), 1664 (CO). 1H NMR (DMSO-d6):
d 2.01e2.14 (2H,
€
theoretical values. Reaction under microwave irradiations was
performed using a CEM Discover Labmate TM apparatus. Mass
spectra were obtained using a MarinerÔ mass spectrometer, Ap-
plied Biosystems (Foster City, CA). A Harvard model 11 syringe
pump (Holliston, MA) was used to infuse the sample solutions. The
ESI source was operated in positive ion mode with an electrospray
voltage of 4.5 kV.
m, CH2), 2.43 (2H, t, J¼6.1 Hz, CH2), 2.84 (2H, t, J¼6.1 Hz, CH2), 5.37
(2H, s, NH2), 6.44 (2H, d, J¼8.7 Hz, H-20 and H-60), 6.83 (2H, d,
J¼8.7 Hz, H-30 and H-50), 7.23e7.35 (5H, m, Ar). 13C NMR (DMSO-
d6):
d
22.7 (t), 23.0 (t), 39.3 (t), 113.2 (dꢃ2), 115.7 (s), 126.6 (dꢃ2),
127.2 (s), 127.7 (dꢃ2), 128.7 (d), 128.8 (s), 130.2 (dꢃ2), 142.2 (s),
148.7 (s),155.9 (s),193.0 (CO). Anal. Calcd for C19H17N3O (303.36): C,
75.23; H, 5.65; N, 13.85. Found: C, 75.08; H, 5.92; N, 13.77. MS m/z

P. Barraja et al. / Tetrahedron 69 (2013) 6474e6477
6477
304 (MHþ). HRMS: [MH]þ, found 304.1409. C19H17N3O requires
304.1444.
128.5 (dꢃ2), 128.6 (s), 129.0 (dꢃ2), 129.1 (d), 129.7 (dꢃ2), 137.6 (s),
139.5 (s), 148.7 (d), 152.0 (s), 161.7 (s). Anal. Calcd for C20H15N3O
(313.35): C, 76.66; H, 4.82; N, 13.41. Found: C, 76.47; H, 4.98; N,
13.59. MS m/z 314 (MHþ). HRMS: [MH]þ, found 314.1314.
C20H15N3O requires 314.1288.
4.5. General procedure for the synthesis of compounds
(9aey)
To a solution of 8aed (5.7 mmol) in anhydrous DMF (14 mL),
NaH (5.7 mmol) was added at 0 ꢀC and the reaction mixture was
stirred for 1 h at rt. The suitable benzyl halide (8.55 mmol) was
added at 0 ꢀC and the reaction mixture was stirred at rt or at reflux.
Then, it was poured onto crushed ice and the solid collected and
dried. Purification by chromatography column, using dichloro-
methane as eluent, gave the expected product. For compounds
9bey see supplementary data.
Acknowledgements
This work was financially supported by Ministero dell’Istruzione
ꢀ
dell’Universita e della Ricerca. We thank the National Cancer In-
stitute (Bethesda, MD) for the antitumour tests reported in this
paper.
Supplementary data
4.5.1. 1-Benzyl-3-phenyl-1,5,6,7-tetrahydro-4H-indazol-4-one
(9a). This compound was obtained from the reaction of 8a with
benzyl bromide after 24 h at rt. White solid; Rf¼0.61 (CH2Cl2/EtOAc
95:5); mp 91e92 ꢀC; yield 69%; IR cmꢁ1: 1667 (CO). 1H NMR
Table 2 describing the GI50 values of compound 13t, the spec-
troscopic data (IR, 1H and 13C NMR) and elemental analysis (C, H, N)
of compounds 7bed, 8bep, 9bey, 10fet, 11aey are reported in the
supplementary data. Supplementary data related to this article can
be found at http://dx.doi.org/10.1016/j.tet.2013.05.083.
(DMSO-d6):
d
2.00e2.12 (2H, m, CH2), 2.44 (2H, t, J¼6.2 Hz, CH2),
2.91 (2H, t, J¼6.2 Hz, CH2), 5.41 (2H, s, CH2), 7.25e7.45 (8H, m, Ar),
8.03 (2H, d, J¼7.5 Hz, H-200 and H-600). 13C NMR (DMSO-d6):
d 21.2 (t),
22.5 (t), 38.6 (t), 52.3 (t),115.0 (s),127.4 (dꢃ2),127.7 (d),127.8 (dꢃ2),
128.3 (dꢃ2), 128.4 (d), 128.7 (dꢃ2), 132.2 (s), 136.3 (s) 149.3 (s),
151.8 (s),192.2 (CO). Anal. Calcd for C20H18N2O (302.37): C, 79.44; H,
6.00; N, 9.26. Found: C, 79.32; H, 6.19; N, 9.08. MS m/z 303 (MHþ).
HRMS: [MH]þ, found 303.1521. C20H18N2O requires 303.1491.
References and notes
1. Nauduri, D.; Reddy, G. Chem. Pharm. Bull. 1998, 46, 1254e1260.
2. Tsuji, K.; Nakamurana, K.; Konishi, N.; Tojo, T.; Ochi, T.; Scnoh, H.; Masuo, M.
Chem. Pharm. Bull. 1997, 45, 987e995.
3. Brune, K. Med. Chem. Toxicol. 1986, 1, 1e9.
4. Floridi, A.; Paggi, M. G.; Marcante, M. L.; Silvestrini, B.; Caputo, A.; De Martino,
C. J. Natl. Cancer Inst. 1981, 66, 497e499.
5. Oded, B.-Y.; Lyons, J. C.; Chang, W. S.; Ross, B. D. J. Neuro-Oncol. 1998, 36,
149e157.
4.6. General procedure for the synthesis of compounds
(10eet, 11aey)
6. Di Cosimo, S.; Ferretti, G.; Papaldo, P.; Carlini, P.; Fabi, A.; Cognetti, F. Drugs
Today 2003, 39, 157e173.
7. Chekulayev, V.; Shevchuk, I.; Chekulayeva, L.; Kahru, A. J. Photochem. Photobiol.,
To a solution of the suitable ketone 8eet, 9aey (0.66 mmol) in
anhydrous DMF (2 mL), DMFDMA (0.88 mL, 6.6 mmol) was added
and the mixture was stirred under microwave irradiation (PW 150,
T 150 ꢀC). The reaction mixture was poured onto crushed ice and
solid was filtered off and dried. For compounds 10fet, 11aey see
supplementary data.
B 1997, 41, 11e21.
8. See for example: Georg, I. G.; Tash, J. S.; Chakrasali, R.; Jakkaraj, S. R. U.S. Patent
2009 US7514463; Chem. Abstr. 2009, 151, 236718.
9. Pan, S. L.; Guh, J. H.; Peng, C. Y.; Wang, S. W.; Chang, Y. L.; Cheng, F. C.; Chang, J.
H.; Kuo, S. C.; Lee, F. Y.; Teng, C.-M. J. Pharmacol. Exp. Ther. 2005, 314, 35e42.
10. Yeo, E.-J.; Chun, J.-H.; Chun, Y.-S.; Cho, Y.-S.; Jang, I.-J.; Cho, H. S.; Kim, M.-S.;
Park, J.-W. Cancer Res. 2006, 66, 6345e6352.
4.6.1. 5-[(Dimethylamino)methylidene]-2,3-diphenyl-2,5,6,7-
tetrahydro-4H-indazol-4-one (10e). This compound was obtained
from 8e after 30 min. Brown solid; Rf¼0.68 (CH2Cl2/EtOAc 95:5); mp
147e148 ꢀC; yield 83%; IR cmꢁ1: 1643 (CO). 1H NMR (DMSO-d6):
11. Huang, L. J.; Shih, M.-L.; Chen, H.-S.; Pan, S.-L.; Teng, C.-M.; Lee, F.-Y.; Kuo, S.-C.
Bioorg. Med. Chem. 2006, 14, 528e536.
12. Barraja, P.; Diana, P.; Lauria, A.; Montalbano, A.; Almerico, A. M.; Dattolo, G.;
Cirrincione, G. Bioorg. Med. Chem. Lett. 2003, 13, 2809e2811.
13. Barraja, P.; Sciabica, L.; Diana, P.; Lauria, A.; Montalbano, A.; Almerico, A. M.;
Dattolo, G.; Cirrincione, G. Bioorg. Med. Chem. Lett. 2005, 15, 2291e2294.
14. Barraja, P.; Diana, P.; Montalbano, A.; Dattolo, G.; Cirrincione, G.; Viola, G.;
Vedaldi, D.; Dall’Acqua, F. Bioorg. Med. Chem. 2006, 14, 8712e8728.
15. Barraja, P.; Diana, P.; Montalbano, A.; Carbone, A.; Cirrincione, G.; Viola, G.;
Salvador, A.; Vedaldi, D.; Dall’Acqua, F. Bioorg. Med. Chem. 2008, 16, 9668e9683.
d
2.79 (2H, t, J¼6.2 Hz, CH2), 2.99 (2H, t, J¼6.2 Hz, CH2), 3.07 (6H, s,
2ꢃ CH3), 7.17e7.34 (11H, m, Ar and CH). 13C NMR (DMSO-d6):
d 22.7
(t), 23.4 (t), 43.2 (qꢃ2), 102.6 (s), 117.5 (s), 125.4 (dꢃ2), 127.5 (dꢃ2),
127.6 (d), 128.5 (d), 128.8 (dꢃ2), 129.1 (s), 130.5 (dꢃ2), 139.2 (s),
142.1 (s), 148.4 (d), 154.7 (s), 181.5 (CO). Anal. Calcd for C22H21N3O
(343.42): C, 76.94; H, 6.16; N,12.24. Found: C, 77.11; H, 5.93; N,12.01.
ꢀ
16. Barraja, P.; Spano, V.; Diana, P.; Carbone, A.; Cirrincione, G. Tetrahedron Lett.
2009, 50, 5389e5391.
ꢀ
17. Barraja, P.; Spano, V.; Diana, P.; Carbone, A.; Cirrincione, G.; Vedaldi, D.; Sal-
vador, A.; Viola, G.; Dall’Acqua, F. Bioorg. Med. Chem. Lett. 2009, 19, 1711e1714.
4.7. General procedure for the synthesis of compounds
(12eet, 13aey)
18. Barraja, P.; Caracausi, L.; Diana, P.; Carbone, A.; Montalbano, A.; Cirrincione, G.;
ꢀ
Brun, P.; Palu, G.; Castagliuolo, I.; Dall’Acqua, F.; Vedaldi, D.; Salvador, A. Bioorg.
Med. Chem. 2010, 18, 4830e4843.
19. Dall’Acqua, F.; Cirrincione, G.; Barraja, P.; Salvador, A. PCT Int. Appl. WO
2011013159; Chem. Abstr. 2011, 154, 182531.
20. Barraja, P.; Diana, P.; Montalbano, A.; Carbone, A.; Viola, G.; Basso, G.; Salvador,
A.; Vedaldi, D.; Dall’Acqua, F.; Cirrincione, G. Bioorg. Med. Chem. 2011, 19,
2326e2341.
To
a solution of the suitable enaminones 10eet, 11aey
(1.0 mmol) in methanol:acetic acid (2:1), hydroxylamine hydro-
chloride (1.1 mmol) was added and the reaction mixture was
heated at reflux for 50 min. The solvent was evaporated, the residue
poured onto crushed ice and the precipitated was filtered, dried
and purified by flash chromatography using dichloromethane as
eluent. For compounds 12fet, 13aey see supplementary data.
21. Barraja, P.; Diana, P.; Montalbano, A.; Carbone, A.; Salvador, A.; Brun, P.; Cas-
tagliuolo, I.; Tisi, S.; Dall’Acqua, F.; Vedaldi, D.; Cirrincione, G. ChemMedChem
2011, 6, 1238e1248.
ꢀ
22. Barraja, P.; Diana, P.; Spano, V.; Montalbano, A.; Carbone, A.; Parrino, B.; Cir-
rincione, G. Tetrahedron 2012, 68, 5087e5094.
23. Kaffy, J.; Pontikis, R.; Carrez, D.; Croisy, A.; Monneret, C.; Florent, J.-C. Bioorg.
Med. Chem. 2006, 14, 4067e4077.
4.7.1. 7,8-Diphenyl-5,7-dihydro-4H-[1,2]oxazolo[5,4-e]indazole
(12e). This compound was obtained from the reaction of 10e. Light
green solid; Rf¼0.38 (CH2Cl2/EtOAc 95:5); mp 157e158 ꢀC; yield
24. Hewing, D. S.; Wang, M.; Philpott, M.; Fedorov, O.; Uttarkar, S.; Filippakopoulos, P.;
Picaud, S.; Vuppusetty, C.; Marsden, B.; Knapp, S.; Conway, S. J.; Heightman, T. D.
J. Med. Chem. 2011, 54, 6761e6770.
ꢀ
56%. 1H NMR (CDCl3):
d
2.92 (2H, t, J¼7.2 Hz, CH2), 3.08 (2H, t,
25. Barraja, P.; Caracausi, L.; Diana, P.; Spano, V.; Montalbano, A.; Carbone, A.;
Parrino, B.; Cirrincione, G. ChemMedChem 2012, 7, 1901e1904.
26. Strakova, I.; Strakovs, A.; Petrova, M. Chem. Heterocycl. Comp. 2005, 41,
1398e1404 (English translation).
J¼7.2 Hz, CH2), 7.23e7.46 (10H, m, Ar), 8.15 (1H, s, H-3). 13C NMR
(CDCl3):
d
19.0 (t), 22.0 (t), 109.0 (s), 110.2 (s), 125.1 (dꢃ2), 127.6 (d),