Synthesis of N-benzylated indole-, indazole- and benzotriazole-4,7-diones

Article abstract of DOI:10.1016/j.tet.2006.10.086

The benzylation of 4,7-dimethoxy-1H-indole (5) followed by an oxidative demethylation led to 1-benzyl-1H-indole-4,7-dione (2) with a 73% overall yield. From the commercially available 7-nitro-1H-indazole (7), a three-step pathway was developed to access 1

Full text of DOI:10.1016/j.tet.2006.10.086

Tetrahedron 63 (2007) 735–739
Synthesis of N-benzylated indole-, indazole- and
benzotriazole-4,7-diones
*
Christelle Marminon, Jacques Gentili, Roland Barret and Pascal Nebois
´
Laboratoire de Chimie Organique, Universite de Lyon, Lyon, F-69003, France; universite Lyon 1, ISPB,
EA 3741 ‘Ecosysteꢀmes et Molecules Bioactives’, 8 avenue Rockefeller, Lyon Cedex 08, F-69373, France
´
´
Received 3 October 2006; revised 25 October 2006; accepted 29 October 2006
Available online 15 November 2006
Abstract—The benzylation of 4,7-dimethoxy-1H-indole (5) followed by an oxidative demethylation led to 1-benzyl-1H-indole-4,7-dione (2)
with a 73% overall yield. From the commercially available 7-nitro-1H-indazole (7), a three-step pathway was developed to access 1-benzyl-
1H-indazole-4,7-dione (3). Two of these steps were investigated in order to improve the process. The direct synthesis of 1-benzyl-1H-benzo-
triazole-4,7-dione (4), through a 1,3-dipolar cycloaddition between benzyl azide and para-benzoquinone (13), was also studied. The simplicity
of the methodologies described offers wide perspectives in obtaining 1-alkylated indole-, indazole- and benzotriazole-4,7-diones.
Ó 2006 Elsevier Ltd. All rights reserved.
OMe
OMe
OMe
OMe
O
O
1. Introduction
1) NaH, DMF
2) BnBr
84%
PIFA
MeCN/H2O
87%
As part of a programme directed to the search of new anti-
parasitic compounds1–3 we previously described2,4 a synthe-
sis of 1-benzyl-1H-benzimidazole-4,7-dione (1) (Fig. 1).
N
H
N
Bn
N
Bn
5
6
2
Scheme 1.
O
Trials to oxidize 6 into 2 with CAN failed, while the use of
phenyliodine(III) bis(trifluoroacetate) (PIFA)8,9 led to the
quinone in good yield.
1 : X=CH, Y=N
Y
2 : X=CH, Y=CH
X
3 : X=N, Y=CH
4 : X=N, Y=N
N
Bn
O
The most useful method to obtain indazole-4,7-dione skele-
ton is the reaction between diazomethane or its derivatives
and a 1,4-benzoquinone substituted at C-2 or/and C-3 posi-
tion(s).10–13 As we needed a C-5 and C-6 unsubstituted qui-
none (3), we developed a new strategy, which is summarized
in Scheme 2.
Figure 1. N-Benzylated benzimidazole-, indole-, indazole- and benzotri-
azole-4,7-diones.
In order to measure the influence of the number and the po-
sition of intracyclic nitrogen atoms on the biological activity,
we planned to develop short routes to indole (2), indazole (3)
and benzotriazole (4) analogues of 1.
Our first attempt of benzylation14 of the commercially avail-
able 7-nitro-1H-indazole (7) gave a mixture of isomers 8 and
9, with a very important selectivity in favour of compound 9
(Table 1, entry 1). We then investigated different alkylating
conditions for improving the ratio of isomer 8. The reaction
temperature seemed to have poor effect (entry 2) while the
substitution of THF by DMF as solvent led to an important
increase in the proportion of 8 (entry 3). By contrast neither
the changes of the time of formation of the anion (entries 4
and 5) nor the amount of the base (entry 6) provided en-
hancement of the ratio. At last, the use of KOH15 (entry 7)
instead of NaH led to the more interesting result, with
a smooth selectivity in favour of the isomer 8 and a quantita-
tive overall yield.
2. Results and discussion
The starting material used in the synthesis of 1-benzyl-1H-in-
dole-4,7-dione (2) was the readily available 4,7-dimethoxy-
1H-indole (5),5–7 which was easily benzylated to afford 6
(Scheme 1).
Keywords: N-Benzylation; Oxidative demethylation; Catalytic hydrogena-
tion; 1,3-Dipolar cycloaddition.
* Corresponding author. Tel.: +33 4 78777138; fax: +33 4 78772867;
e-mail: nebois@univ-lyon1.fr
0040–4020/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.10.086

736
C. Marminon et al. / Tetrahedron 63 (2007) 735–739
5.8%
6.2%
benzylation
step
H
3
3
H
N
N
N Bn
CH2
N
N
N
N
N
N
N
H
H
11.1%
H
Bn
8: R=NO2
NO2
R
R
CH2
NH2
NH2
6.0%
9: R=NO2
7
reduction
step
16.7%
4.8%
H
12.0%
5.9%
1.9%
10
11
11: R=NH2
10: R=NH2
PIFA
MeCN/H2O
PIFA
85%
63%
MeCN/H2O
Figure 2. Correlations observed from NOE experiments carried out on
compounds 10 and 11.
O
O
O
N
N
N
Bn
ꢁ
Because of the failures noticed in the presence of Fremy’s
N
Bn
salt,21 oxidations of amino derivatives 10 and 11 were finally
O
achieved using PIFA.8
3
12
Scheme 2.
Structural assignments of regioisomers were based on the
structural determination of amino derivatives 10 and 11,
which was established from NOE experiments (Fig. 2).
No correlation was observed for H-3 in the case of com-
pound 10, while a significant one was evidenced for com-
pound 11.
Table 1. Benzylation of 7-nitro-1H-indazole (7)
Entry Base (equiv) Solvent Timea Temp Ratio
Overall
yield
(min)
(ꢀC)
8/9
1
2
3
4
5
6
7
NaH (1,2)
NaH (1,2)
NaH (1,2)
NaH (1,2)
NaH (1,2)
NaH (2)
THF
THF
20
20
20
2
60
60
60
20
0
2/98b
85
71
98
85
67
100
99
6/94
40/60
39/61
39/61
43/57
52/48
Benzotriazole-4,7-dione (4) was obtained from a direct path-
way using a 1,3-dipolar cycloaddition22 of benzyl azide23 on
para-benzoquinone (13)24,25 (Scheme 3).
DMF
DMF
DMF
DMF
DMF
20
20
20
20
20
KOH (1,2)
O
O
O
O
a
Bn
Before addition of BnBr.
A similar ratio was previously reported16 using KOH/Me2SO4 in water.
b
N
N
N
N
N
N
N
N
N
N3Bn
N
N
N
N
N
N
Bn
Bn
Bn
Bn
O
13
O
O
14
O
15
After separation of compounds 8 and 9 by column chroma-
tography, we studied the reduction of the nitro group of 8.
The use of tin/hydrochloric acid17,18 (Table 2, entry 1)
gave surprisingly a poor yield of amino derivative 10 with
an important formation of a by-product. The mass spectra
of this one indicated a probable chlorination of the benzenic
ring, as previously reported.17 In the presence of N,N-di-
methylhydrazine and ferric chloride19 (entry 2), the yield
of 10 was appreciably increased, but the best result was
obtained from catalytic hydrogenation in acidic medium20
(entry 3). The same method was used to obtain compound
11 from isomer 9 (yield: 63%).
4
Scheme 3.
The first reaction, carried out at 40 ꢀC, gave a mixture of 4
and undesirable tricyclic derivative 14 (Table 3, entry 1).
In order to reduce the formation of di-addition compound,
we explored different reaction conditions. A lower tempera-
ture led to better result, but a much longer time of reaction
was required to obtain acceptable yield of 4 (entry 2). The
substitution of ethyl acetate by acetonitrile as solvent had
no significant effect (entry 3) while reducing the amount
of benzyl azide (entry 4) gave the best result. In the presence
of 2 equiv of benzyl azide in refluxed ethyl acetate (entry 5),
a mixture of regioisomers 14 and 15 was obtained. In all the
above experiments, formation of numerous side products
was encountered. Structural assignments of 14 and 15
were based on their 13C NMR spectrum. In the case of
compound 14, only one signal was observed in the range
of carbonyl chemical shifts, while two distinct singlets were
present for 15.
Table 2. Reduction of 1-benzyl-7-nitro-1H-indazole (8)
Entry Reactants
Time Temp Yield of
(ꢀC)
(h)
10 (%)
1
2
3
Sn, HCl
1.5
100
65
20
14
60
82
Me2NNH2, FeCl3$6H2O, MeOH 18
H2, Pd/C, EtOAc, AcOH 24
Table 3. Reaction of benzyl azide with para-benzoquinone (13)
Entry
Equiv of N3Bn
Solvent
Time (days)
Temp (ꢀC)
Recovered 13 (%)
Yield of 4 (%)
Yield of 14 and 15 (%)
Ratio 14/15
1
2
3
4
5
1
1
1
0.75
2
AcOEt
AcOEt
MeCN
AcOEt
AcOEt
6
21
21
21
2
40
20
20
20
80
21
20
15
28
0
19a
26a
25a
32b
0
5
100/0
—
—
—
78/22
Traces
Traces
Traces
32
a
Calculated as conversion rate of 13.
Calculated from benzyl azide.
b

C. Marminon et al. / Tetrahedron 63 (2007) 735–739
737
3. Conclusion
addition, stirring was maintained for 15 min at 20 ꢀC. The
reaction mixture was extracted with 3ꢁ25 mL of CH2Cl2,
washed with 3ꢁ25 mL of water, dried over Na2SO4
and evaporated under vacuum. The residue was purified
by column chromatography (CH2Cl2/petroleum ether, 4/1);
yield 31 mg (87%). Orange crystals; Rf¼0.55 (CH2Cl2);
We developed useful and short accesses to C-5 and C-6
unsubstituted 1-benzylated indole-, indazole- and benzotri-
azole-4,7-diones. The evaluation of antiparasitic potential
of all compounds synthesized is actually underway. The
versatility of the methodologies described in this paper will
be built on in a future structure–biological activity study.
1
mp 135 ꢀC; IR (KBr) 1650, 1496, 1405 cmꢂ1; H NMR
(CDCl3) d 7.28–7.16 (5H, m, H Ph), 6.84 (1H, d,
J¼2.8 Hz, H-2), 6.55 (1H, d, J¼2.8 Hz, H-3), 6.51 (1H,
d, J¼10.3 Hz, H-5 or H-6), 6.46 (1H, d, J¼10.3 Hz,
H-5 or H-6), 5.49 (2H, s, CH2); 13C NMR (CDCl3) d
183.7, 178.4, 137.7, 137.4, 136.5, 130.0, 129.3 (3C), 128.7
(2C), 128.0, 127.4, 108.1, 52.4. Anal. Calcd for
C15H11NO2$0.15H2O: C, 75.08; H, 4.75; N, 5.84. Found:
C, 75.53; H, 5.22; N, 5.47. HRMS calcd for C15H12NO2:
238.0868 [M+H]+, found: 238.0869.
4. Experimental
4.1. General procedures
€
Melting points were measured with a Buchi apparatus (cap-
illary tube). The H (300 MHz) and 13C NMR (75 MHz)
1
spectra were recorded with a Bruker AM 300 spectropho-
tometer. The chemical shifts are reported in parts per million
(d) using tetramethylsilane (TMS) as an internal reference.
J values are given in hertz. The infrared spectra were recorded
with a Perkin–Elmer 1310 spectrometer. Mass spectra (EI)
were recorded with a GC–MS Nermag R10-10 spectrometer.
Elemental analyses were performed at the Centre de Micro-
analyse du CNRS at Solaize (France). Column chromato-
4.3. Indazole derivatives
4.3.1. 1-Benzyl-7-nitro-1H-indazole (8) and 2-benzyl-7-
nitro-1H-indazole (9). To a solution of 7-nitroindazole (7)
(0.3 g, 1.84 mmol) in dry DMF (3 mL) was added at 20 ꢀC
NaH (60% in mineral oil, 89 mg, 2.21 mmol). After stirring
for 10 min, benzyl bromide (264 mL, 2.21 mmol) was
rapidly added and stirring maintained for 2 h. The solution
was then poured into ice-water (60 mL) and diluted HCl
was added to adjust the pH to about 6. This solution was
extracted with AcOEt (2ꢁ60 mL) and the combined org-
anic layers were washed with water and brine, dried
over Na2SO4 and evaporated under vacuum. The residue
was purified by column chromatography (AcOEt/petroleum
ether, 1/4) leading to 8 (yield 185 mg, 39%) and 9 (yield
275 mg, 59%). Compound 8: orange powder; Rf¼0.67
(AcOEt/petroleum ether, 1/2); mp 65 ꢀC; IR (KBr) 1620,
˚
graphy was carried out with Matrex (60 A, 35–70 mm)
acidic silica gel. 7-Nitroindazole and 1,4-benzoquinone
were obtained from Sigma (L’Isle d’Abeau, France). 4,7-Di-
methoxy-1H-indole 55,6 and benzyl azide23 were prepared
according to the procedures described in the literature.
4.2. Indole derivatives
4.2.1. 1-Benzyl-4,7-dimethoxy-1H-indole (6). A solution
of 4,7-dimethoxy-1H-indole 5 (0.22 g, 1.24 mmol) in dry
DMF (20 mL) was added dropwise at 20 ꢀC, over 15 min,
to a suspension of NaH (60% in mineral oil, 0.134 g,
3.72 mmol) in the same solvent (5 mL). The reaction mix-
ture was stirred for 15 min and benzyl bromide (0.16 mL,
1.24 mmol) was rapidly added. After stirring for 12 h,
DMF was removed under vacuum. The residue was then
dissolved in CH2Cl2 (50 mL). The solution was washed
with a saturated K2CO3 solution (4ꢁ10 mL), dried over
Na2SO4 and evaporated under vacuum. The residue was pu-
rified by column chromatography (CH2Cl2/petroleum ether,
4/1); yield 0.28 g (84%). Light white crystals; Rf¼0.76
(CH2Cl2/petroleum ether, 4/1); mp 62 ꢀC; IR (KBr) 1525,
1538, 1338 cmꢂ1 1H NMR (DMSO-d6) d 8.58 (1H, s,
;
H-3), 8.32 (1H, dd, J¼1.1, 8.0 Hz, H-6), 8.15 (1H, dd,
J¼0.9, 7.7 Hz, H-4), 7.37 (1H, dd, J¼7.7, 8.0 Hz, H-5),
7.31–7.19 (3H, m, H Ph), 6.93 (2H, dd, J¼2.1, 8.1 Hz,
H Ph), 5.84 (2H, s, CH2); 13C NMR (DMSO-d6) d 137.2,
135.5, 134.9, 129.8, 129.1, 128.9 (2C), 128.6, 127.5, 126.5
(2C), 124.9, 120.6, 55.7. Anal. Calcd for C14H11N3O2: C,
66.40; H, 4.38; N, 16.59; O, 12.63. Found: C, 66.10; H,
4.23; N, 16.42; O, 12.60. Compound 9: yellow solid;
Rf¼0.33 (AcOEt/petroleum ether, 1/2); mp 123 ꢀC; IR
(KBr) 1511, 1332, 1295 cmꢂ1 1H NMR (DMSO-d6)
;
d 8.92 (1H, s, H-3), 8.34 (1H, dd, J¼0.8, 8.5 Hz, H-6),
8.31 (1H, d, J¼8.5 Hz, H-4), 7.45–7.32 (5H, m, H Ph),
7.28 (1H, dd, J¼8.3, 8.7 Hz, H-5), 5.83 (2H, s, CH2); 13C
NMR (DMSO-d6)26 d 139.8, 136.6, 136.2, 130.2, 128.7
(2C), 128.1, 128.0 (2C), 127.4, 125.3, 124.9, 119.9, 56.7.
Anal. Calcd for C14H11N3O2: C, 66.40; H, 4.38; N, 16.59;
O, 12.63. Found: C, 66.32; H, 4.42; N, 16.53; O, 12.78.
1
1453, 1260 cmꢂ1; H NMR (CDCl3) d 7.25–7.07 (5H, m,
H Ph), 6.95 (1H, d, J¼3.0 Hz, H-2), 6.59 (1H, d,
J¼3.0 Hz, H-3), 6.50 (1H, d, J¼8.1 Hz, H-5 or H-6), 6.36
(1H, d, J¼8.1 Hz, H-5 or H-6), 5.61 (2H, s, CH2), 3.91
(3H, OCH3), 3.77 (3H, OCH3); 13C NMR (CDCl3)
d 147.6, 142.5 (2C), 139.6 (2C), 128.5 (2C), 128.0, 127.1,
126.6 (2C), 102.6, 99.4, 98.4, 55.9, 55.6, 52.2. Anal. Calcd
for C17H17NO2: C, 76.38; H, 6.41; N, 5.24. Found: C,
76.32; H, 6.37; N, 5.25. HRMS calcd for C17H18NO2:
268.1338 [M+H]+, found: 268.1338.
4.3.2. 7-Amino-1-benzyl-1H-indazole (10). A solution of
nitro compound 8 (1.75 g, 6.92 mmol) in AcOEt (35 mL)
and acetic acid (12.5 mL) was added to a suspension of pre-
reduced 10% Pd/C (0.58 g, 33% w/w) in AcOEt (15 mL).
The mixture was then stirred under dihydrogen pressure
(4 bar) for 6 h, filtered through Celite, neutralized with
diluted cooled NH4OH and extracted with AcOEt
(2ꢁ50 mL). The combined organic layers were washed
with brine, dried over Na2SO4 and evaporated under
vacuum. The residue was then purified by column
4.2.2. 1-Benzyl-1H-indole-4,7-dione (2). A solution of
phenyliodine(III) bis(trifluoroacetate) (PIFA) (0.257 g,
0.6 mmol) in 7.5 mL of acetonitrile and 7.5 mL of water
was added dropwise at 0 ꢀC, over 15 min, to a solution of
1-benzyl-4,7-dimethoxy-1H-indole (6) (40 mg, 0.15 mmol)
in the same mixture of solvents (15 mL). At the end of the

738
C. Marminon et al. / Tetrahedron 63 (2007) 735–739
chromatography (AcOEt/petroleum ether, 1/3) with silica
gel previously neutralized with NEt3; yield 1.270 g (82%).
Light pink solid; Rf¼0.47 (AcOEt/petroleum ether, 1/2);
was filtered and the filtrate evaporated under vacuum. The
residue was purified by column chromatography (dichloro-
methane/petroleum ether, 2/1) leading to recovered 13
(0.217 g) and 4; yield 0.540 g (32% calculated from benzyl
azide). Light brown solid; Rf¼0.34 (dichloromethane);
mp 131 ꢀC; IR (KBr) 3329, 1585, 727 cmꢂ1 1H NMR
;
(DMSO-d6) d 8.01 (1H, s, H-3), 7.33–7.20 (3H, m, H Ph),
7.18–7.11 (2H, m, H Ph), 7.06 (1H, dd, J¼1.0, 8.0 Hz,
H-4), 6.90 (1H, dd, J¼7.3, 8.0 Hz, H-5), 6.63 (1H, dd,
J¼1.0, 7.3 Hz, H-6), 5.86 (2H, s, CH2), 5.17 (2H, br s,
NH2); 13C NMR (DMSO-d6) d 140.0, 134.3, 134.2, 132.1,
129.2, 128.0, 127.9, 127.8, 127.7, 127.1, 122.7, 112.0,
110.4, 54.9. Anal. Calcd for C14H13N3: C, 75.31; H, 5.87;
N, 18.82. Found: C, 75.40; H, 5.97; N, 19.04.
1
mp 110 ꢀC; IR (KBr) 1680, 1497, 1032 cmꢂ1; H NMR
(DMSO-d6) d 7.54–7.43 (2H, m, H Ph), 7.42–7.31 (3H, m,
H Ph), 6.86 (1H, d, J¼10.5 Hz, H-5 or H-6), 6.79 (1H, d,
J¼10.5 Hz, H-5 or H-6), 5.90 (2H, s, CH2); 13C NMR
(DMSO-d6) d 178.5, 176.8, 143.9, 138.3, 136.5, 133.6,
131.6, 129.1, 129.0 (2C), 128.6 (2C), 53.6; HRMS calcd
for C13H10N3O2: 240.0773 [M+H]+, found: 240.0780.
4.3.3. 7-Amino-2-benzyl-2H-indazole (11). Compound 11
was prepared as above from 9 (1.44 g, 5.69 mmol); yield
0.849 g (67%). Red oil; Rf¼0.17 (AcOEt/petroleum ether,
4.4.2. 1,5-Dibenzyl-1H,5H-benzo[1,2-d;4,5-d0]bistriazole-
4,8-dione (14) and 1,7-dibenzyl-1H,7H-benzo[1,2-d;
4,5-d0]bistriazole-4,8-dione (15). A mixture of 1,4-benzo-
quinone (13) (0.5 g, 4.63 mmol) and benzyl azide (1.23 g,
9.26 mmol) in ethyl acetate (73 mL) was refluxed for 54 h.
Then, the mixturewas filtered and pure bistriazole 14 was ob-
tained (0.303 g). The filtrate was evaporated under vacuum
and the residue purified by column chromatography (di-
chloromethane) to afford 0.242 g of an equimolar mixture
(established from the deconvolution of the methylene signals
of 1H NMR spectrum) of the two isomers 14 and 15; overall
yield: 32%, 14/15: 78/22. Compound 14: beige solid;
Rf¼0.39 (dichloromethane); mp 260 ꢀC (degradation); IR
1
1/2); IR (KBr) 3435, 1627, 742 cmꢂ1; H NMR (DMSO-
d6) d 8.31 (1H, s, H-3), 7.45–7.24 (5H, m, H Ph), 6.88
(1H, dd, J¼0.9, 8.1 Hz, H-4), 6.80 (1H, dd, J¼7.0, 8.1 Hz,
H-5), 6.30 (1H, dd, J¼0.9, 7.0 Hz, H-6), 5.64 (2H, s,
CH2), 5,29 (2H, br s, NH2); 13C NMR (DMSO-d6)
d 141.5, 136.5, 135.7, 129.1, 128.1 (2C), 127.4, 127.0
(2C), 122.6, 122.2, 108.3, 104.7, 56.2; HRMS calcd for
C14H14N3: 224.1188 [M+H]+, found: 224.1191.
4.3.4. 1-Benzyl-1H-indazole-4,7-dione (3). A solution of
aminoindazole 10 (40 mg, 0.179 mmol) in acetonitrile
(1.5 mL) and water (0.5 mL) was added dropwise at 0 ꢀC
to PIFA (193 mg, 0.45 mmol) in the same mixture of sol-
vents (2 mL). The solution was stirred for 30 min at 20 ꢀC.
Then, water (50 mL) and AcOEt (50 mL) were added. The
organic layer was washed with brine to adjust the pH to
about 7, dried over Na2SO4 and evaporated under vacuum.
The residue was purified by column chromatography
(AcOEt/petroleum ether, 1/5); yield 40 mg (85%). Red
solid; Rf¼0.64 (AcOEt/petroleum ether, 1/2); mp 111 ꢀC;
1
(KBr) 1699, 1520, 1496, 1476, 1376, 950 cmꢂ1; H NMR
(DMSO-d6) d 7.50–7.35 (10H, m, H Ph), 6.05 (4H, s, CH2);
13C NMR (DMSO-d6) d 168.2 (2C), 135.1 (2C), 134.5 (4C),
128.7 (4C), 128.4 (2C), 128.0 (4C), 52.8 (2C). Anal. Calcd
for C20H14N6O2$0.1H2O: C, 64.55; H, 3.84; N, 22.58;
O, 9.03. Found: C, 64.37; H, 3.76; N, 22.61; O, 9.23.
Compound 15: Rf¼0.39 (dichloromethane); 1H NMR
(DMSO-d6) d 7.50–7.35 (10H, m, H Ph), 6.03 (4H, s, CH2);
13C NMR (DMSO-d6) d 170.7, 165.7, 145.8 (2C), 134.9 (2C),
134.4 (2C), 128.8 (4C), 128.6 (2C), 128.0 (4C), 52.8 (2C).
IR (KBr) 1677, 1526, 712 cmꢂ1 1H NMR (DMSO-d6)
;
References and notes
d 8.31 (1H, s, H-3), 7.45–7.35 (5H, m, H Ph), 6.90 (1H, d,
J¼10.4 Hz, H-5 or H-6), 6.84 (1H, d, J¼10.4 Hz, H-5 or
H-6), 5.76 (2H, s, CH2); 13C NMR (DMSO-d6) d 181.5,
177.6, 138.4, 137.2, 136.4, 135.8, 135.7, 128.6 (2C),
128.0, 127.7 (2C), 121.1, 54.0. Anal. Calcd for
C14H10N2O2: C, 70.58; H, 4.23; N, 11.76; O, 13.43. Found:
C, 70.16; H, 4.23; N, 11.61; O, 13.28.
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H Ph), 6.81 (1H, d, J¼10.4 Hz, H-5 or H-6), 6.74 (1H, d,
J¼10.4 Hz, H-5 or H-6), 5.45 (2H, s, CH2); 13C NMR
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