Synthesis of a novel pentacycle: 8-Methyl-10-phenylpyrazolo[4′, 3′: 5,6]-pyrano[3,2-c]-[1,10]phenanthrolin-7(10H)-one

Article abstract of DOI:10.1007/s10593-008-0106-5

The title compound - a derivative of a hitherto unknown pentacyclic ring system - results from the reaction of 3-methyl-1-phenyl-2-pyrazolin-5-one and 4-chloro-1,10-phenanthroline-3-carbonyl chloride in the presence of Ca(OH) ₂ in boiling 1,4-dioxane.

Full text of DOI:10.1007/s10593-008-0106-5

Chemistry of Heterocyclic Compounds, Vol. 44, No. 6, 2008
SYNTHESIS OF A NOVEL PENTACYCLE:
8-METHYL-10-PHENYLPYRAZOLO[4',3':5,6]-
PYRANO[3,2-c]-[1,10]PHENANTHROLIN-
7(10H)-ONE
G. A. Eller, D. Habicht, and W. Holzer
The title compound – a derivative of a hitherto unknown pentacyclic ring system – results from the
reaction of 3-methyl-1-phenyl-2-pyrazolin-5-one and 4-chloro-1,10-phenanthroline-3-carbonyl chloride
in the presence of Ca(OH)2 in boiling 1,4-dioxane.
Keywords: pyrazolones, acylations, fused ring systems, NMR spectroscopy.
In the course of our investigations on novel heteroaromatic ring systems bearing a pyrano-
[2,3-c]pyrazol-4(1H)-one moiety [1–5], we envisaged the synthesis of a new representative containing a
1,10-phenanthroline-ring system. Similarly to our previous works, the planned synthesis should include the
selective C(4)-acylation of a pyrazolone (2-pyrazolin-5-one) with an appropriate o-haloarenecarbonyl chloride
O
O
OEt
HN
NH2
OEt
COOEt
HN
N
N
N
POCl3
EtOCH=C(COOEt)2
O
O
∆
–EtOH
3
2
1
O
O
O
OH
SOCl2/DMF
HN
OH
OEt
N
N
N
N
N
1. KOH/H2O
2. HCl/H2O
Cl
Cl
N
+
5
6
4
O
Cl
N
Cl
7
__________________________________________________________________________________________
Department of Drug and Natural Product Synthesis, University of Vienna, A-1090 Vienna, Austria;
e-mail: gernot.eller@univie.ac.at; e-mail: wolfgang.holzer@univie.ac.at. Translated from Khimiya
Geterotsiklicheskikh Soedinenii, No. 6, pp. 884-890, June, 2008. Original article submitted January 20, 2008.
0009-3122/08/4406-0709©2008 Springer Science+Business Media, Inc.
709

(i.e., 4-chloro-1,10-phenanthroline-3-carbonyl chloride (7)) under "Jensen" conditions (Ca(OH)2, refluxing
1,4-dioxane) [6] and subsequent cyclization of the resulting ketone to form the central pyrone moiety.
The preparation of that acid chloride – key intermediate 7 – was accomplished via a multi-step
procedure. According to [7], the reaction of 8-aminoquinoline (1) with diethyl ethoxymethylenemalonate gave
enamine 2, which was cyclized into the phenanthroline derivative 3 in hot diphenyl ether. Subsequent treatment
of 3 with thionyl chloride/DMF converted the oxygen function in position 4 into a chlorine substituent
(compound 4) [8].
Saponification of ester 4 by treatment with aqueous KOH resulted in a precipitate, which after
acidification should give the desired o-chlorocarboxylic acid 5. However, NMR spectroscopic analysis (in
DMSO-d6 due to solubility reasons) of the thus obtained product revealed a mixture of initially two species 5
and 6, with the amount of compound 5 rapidly decreasing for the benefit of compound 6. Obviously, in polar
DMSO-d6, always containing more or less trace water, the chloro group of compound 5 is replaced by an OH
function resulting in the formation of compound 6, which is present as phenanthrolin-4-one. As this process
1
occurred relatively fast, only H NMR data could be acquired from compound 5. Fortunately, when the raw
material resulting from the saponification reaction was treated with SOCl2 the acid chloride 7 was formed as the
sole product, which was immediately employed in the next reaction step without any further purification.
Finally, the pyrazolone 8 was reacted with the acid chloride 7 in the presence of Ca(OH)2 in boiling
1,4-dioxane. The thus obtained solid turned out to be already the desired pentacyclic title compound 10, which
was proved by means of C,H,N-analysis and MS, IR, 1H, and 13C NMR spectra. As expected, due to fact that the
chloro atom in position 4 of the phenanthroline system is located in an "activated" position, the cyclization
occurred under the conditions of the acylation reaction and thus no intermediate 4-aroylpyrazol-5-ol (9) could be
isolated [1, 2, 4, 5].
O
Me
Me
Ca(OH)2
N
7
+
N
N
N
1,4-dioxane
O
O
H
N
N
Cl
Ph
Ph
8
9 (not isolated)
O
6
7
Me
8
N
N
N
3
2
O
N
12
Ph
13
1
10
All the compounds prepared except the intermediate acid chloride 7 were thoroughly investigated with
respect to their NMR spectra. Thus, unambiguous assignment of all proton, carbon, and nitrogen resonances was
13
1
carried out by combined application of different standard NMR methods [9]. Moreover, many C, H coupling
constants could be unequivocally assigned using 2D (δ, J) INEPT spectra with selective excitation [10]. Thus,
for instance, the two ethyl ester moieties at the exocyclic double bond of compound 2 could be distinguished
3
considering the vicinal JCO,=CH coupling constants: Whereas the (Z)-ester carbonyl-C resonance showed such a
coupling of 10.0 Hz, the corresponding (E)-C=O signal was split with 4.3 Hz, indicating the cis position of the
coupled nuclei in the latter case.
The NMR spectra of compound 3 clearly revealed this compound to exist solely as phenanthrolin-4-one
and not as 4-hydroxyphenanthroline in DMSO-d6 solution. This assignment was based on the following criteria:
710

The relatively large chemical shift of C-4 (δ 173.0 ppm), indicating this carbon to be a carbonyl-type C-atom, a
pronounced NOE on the signal due to H-2 upon irradiation of the resonance of the acidic proton, and mainly the
low-field chemical shift of N-1 (δ −249.5 ppm) – which cannot be a pyridine-type N-atom – and its correlation
15
1
to the acidic H (δ 12.77 ppm) in an N, H HSQC experiment. In comparison, the 15N chemical shift of N-1 in
the "aromatic" 4-chlorophenathroline 4 is -82.4 ppm. On basis of similar criteria the phenanthrolin-4-one
structure of the acid 6 was proved.
Selected NMR data of compounds 2 and 3
–249.5 ppm
3J = 4.3 Hz
NOE
HMBC
12.77 ppm
H
H
3J = 10.0 Hz
HN
H
COOEt
O
COOCH2CH3
COOCH2CH3
HMBC
N
HSQC
N
N
173.0 ppm
3 (DMSO-d6)
2 (CDCl3)
Selected NMR data of compound 10
10.30
O
H
13.9
2.81
172.5
106.5
148.4
H3C
116.2
N
147.6
149.2
145.5
151.3
N
H
N
H
9.36
7.65
O
H
N
*
156.8
118.6
137.3
124.3
H
8.23
129.9
128.7
H
H
136.3
119.0
121.7
8.47
H
H
130.0
H
7.66
8.33
8.06
128.0
H
7.46
10 (pyridine-d5)
* not found
The title compound 10 turned out to have a very limited solubility. Thus, in DMSO-d6 solution only a
1H NMR spectrum could be taken in a long-time run. However, a slightly better solubility in pyridine-d5
permitted the unequivocal identification of all 13C resonances.
EXPERIMENTAL
Melting points were determined on a Reichert–Kofler hot-stage microscope and are uncorrected. Mass
spectra were obtained on a Shimadzu QP 1000 instrument (EI, 70 eV). IR spectra were recorded on a Perkin–
Elmer FTIR 1605 spectrophotometer. Elemental analyses were performed at the Microanalytical Laboratory,
711

1
University of Vienna. The H and 13C NMR spectra were recorded on a Varian UnityPlus 300 spectrometer at
28°C or on a Bruker Avance 500 spectrometer at 293 K. The center of the solvent signal was used as an internal
standard which was related to TMS with δ = 7.26 (1H in CDCl3), δ = 2.49 (1H in DMSO-d6), δH-4 = 7.55 (1H in
pyridine-d5), δ = 77.0 (13C in CDCl3), δ = 39.5 (13C in DMSO-d6), and δC-4 = 135.5 ppm (13C in pyridine-d5). The
digital resolutions were 0.2 Hz/data point in the 1H NMR spectra and 0.4 Hz/data point in the 13C NMR spectra
(1H broadband decoupling or gated decoupling). 15N NMR spectra were obtained on a Bruker Avance 500
instrument with a "directly" detecting broadband observe probe and were referenced against external
nitromethane (coaxial capillary). Systematic names were generated with ACD/Name [11] according to the
IUPAC recommendations and were also checked manually to ensure correct use of nomenclature within this
publication [12]. Compound 8 was purchased from Sigma-Aldrich, Germany. Product yields were not
optimized.
Diethyl [(quinolin-8-ylamino)methylidene]propanedioate (2). This compound was prepared similarly
to a known procedure [7] starting of 8-aminoquinoline (1) (5.02 g, 35 mmol) and diethyl
ethoxymethylenemalonate (7.53 g, 35 mmol) to yield 9.56 g (87%) of compound 2 as green-brownish needles;
1
mp 111–112°C (mp 110–112°C [7]). IR spectrum (KBr), ν, cm−1: 1683, 1645. H NMR spectrum (300 MHz,
CDCl3), δ, ppm (J, Hz): 12.32 (1H, d, 3JNH,=CH = 14.4, NH); 8.93 (1H, dd, 3J2,3 = 4.2, 4J2,4 = 1.7, H-2); 8.77 (1H,
3
3
4
d, JCH,NH = 14.4, =CH); 8.14 (1H, dd, J3,4 = 8.3, J4,2 = 1.7, H-4); 7.51 (2H, m, H-5,6); 7.50 (1H, t, H-7); 7.46
(1H, dd, 3J3,2 = 4.2, 3J3,4 = 8.3, H-3); 4.41 (2H, q, 3JOCH2,CH3 = 7.1, (Z)-ester OCH2); 4.29 (2H, q, 3JOCH2,CH3 = 7.1,
3
3
(E)-ester OCH2); 1.44 (3H, t, JCH3,OCH2 = 7.1, (Z)-ester CH3); 1.36 (3H, t, JCH3,OCH2 = 7.1, (E)-ester CH3). 13C
NMR spectrum (75 MHz, CDCl3), δ, ppm (J, Hz): 167.7 (3JCO,=CH = 10.0, JCO,OCH2 = 3.0, (Z)-ester CO); 166.1
3
(3JCO,=CH = 4.3, JCO,OCH = 3.1, (E)-ester CO); 149.4 (1J = 180.0, JC-2,H-3 = 3.7, JC-2,H-4 = 7.7, C-2); 148.8
3
2
3
2
(1J = 167.9, =CH); 138.7 (C-8a); 136.0 (C-8); 135.9 (C-4); 128.6 (C-4a); 126.6 (C-6); 122.4 (C-5); 122.1
(1J = 164.3, JC-3,H-2 = 9.0, C-3); 110.3 (C-7); 95.4 (C(COOEt)2); 60.4 (1J = 147.5, JOCH ,CH = 4.4, (Z)-ester
2
2
2
3
OCH2); 60.1 (1J = 147.1, JOCH ,CH = 4.4, (E)-ester OCH2); 14.4 (1J = 126.7, JCH ,OCH = 2.7, (E)-ester CH3);
2
2
2
3
3
2
14.3 (1J = 126.9, JCH ,OCH = 2.7, (Z)-ester CH3). 15N NMR spectrum (50 MHz, CDCl3), δ, ppm: −87.1 (N-1);
2
3
2
-260.5 (NH). Mass spectrum, m/z (Irel, %): 314 [M]+ (9), 241 (81), 213 (27), 196 (26), 195 (26), 169 (25), 168
(100), 155 (33), 140 (23), 129 (38), 128 (36), 101 (20).
Ethyl 4-oxo-1,4-dihydro-1,10-phenanthroline-3-carboxylate (3). This compound was prepared
similarly to a known procedure [7] starting from 4.06 g (13 mmol) of compound 2 to yield 1.87 g (54%) of oxo
1
ester 3 as a beige powder; mp 242–246°C (mp 237–241°C [7]). IR spectrum (KBr), ν, cm−1: 1706, 1631. H
3
4
NMR spectrum (300 MHz, DMSO-d6), δ, ppm (J, Hz): 12.77 (1H, s, NH); 9.03 (1H, dd, J9,8 = 4.3, J9,7 = 1.6,
3
4
3
H-9); 8.51 (1H, s, H-2); 8.50 (1H, dd, J7,8 = 7.8, J7,9 = 1.6, H-7); 8.18 (1H, d, J5,6 = 8.8, H-5); 7.83 (1H, d,
3J6,5 = 8.8, H-6); 7.78 (1H, dd, J8,7 = 7.8, J8,9 = 4.3, H-8); 4.24 (2H, q, JOCH2,CH3 = 7.1, OCH2); 1.28 (3H, t,
3JCH3,OCH2 = 7.1, CH3). 13C NMR spectrum (75 MHz, DMSO-d6), δ, ppm (J, Hz): 173.0 (3JC-4,H-2 = 6.6, 3JC-4,H-5 = 3.2,
C-4); 164.5 (3JCO,CH2 = 3.3, 3JCO,H-2 = 3.7, CO); 149.9 (1J = 180.9, 2JC-9,H-8 = 3.7, 3JC-9,H-7 = 7.6, C-9); 143.8 (1J = 179.8,
C-2); 138.6 (3JC-10a,H-9 = 12.2, 3JC-10a,H-6 = 6.5, 3JC-10a,H-7 = 5.8, C-10a); 136.6 (1J = 165.6, 3JC-7,H-6 = 4.2, 3JC-7,H-9 = 5.8,
C-7); 136.0 (3JC-10b,H-5 = 7.1, C-10b); 129.0 (2JC-6a,H-6 = 1.9, 2JC-6a,H-7 = 1.5, 3JC-6a,H-5 = 9.7, 3JC-6a,H-8 = 7.5, 4JC-6a,H-9 = 1.3,
3
4
3
C-6a); 126.0 (3JC-4a,H-6 = 8.7, C-4a); 124.2 (1J = 166.5, JC-8,H-9 = 8.8, C-8); 123.4 (1J = 164.4, JC-6,H-5 = 1.7,
3JC-6,H--7 = 4.7, C-6); 122.4 (1J = 164.5, 2JC-5,H-6 = 1.6, C-5); 112.6 (C-3); 59.7 (1J = 147.5, 2JOCH2,CH3 = 4.4, OCH2);
14.3 (1J = 126.7, 2JCH3,OCH2 = 2.6, CH3). 15N NMR spectrum (50 MHz, DMSO-d6), δ, ppm: -83.4 (N-10); -249.5
(N-1). Mass spectrum, m/z (Irel, %): 268 [M]+ (15), 223 (20), 222 (17), 196 (100), 168 (33), 140 (46).
Ethyl 4-chloro-1,10-phenanthroline-3-carboxylate (4) was prepared similarly to a known procedure
[8] starting of compound 3 (3.99 g, 15 mmol) and SOCl2 (15 ml) to yield 3.99 g (93%) as a beige solid; mp
112-116°C (mp 121°C [13]). IR spectrum (KBr), ν, cm−1: 1709. 1H NMR spectrum (300 MHz, CDCl3), δ, ppm
(J, Hz): 9.38 (1H, s, H-2); 9.17 (1H, dd, 3J9,8 = 4.3, 4J9,7 = 1.7, H-9); 8.27 (1H, d, 3J5,6 = 9.1, H-5); 8.20 (1H, dd,
3J7,8 = 8.0, 4J7,9 = 1.7, H-7); 7.84 (1H, d, 3J6,5 = 9.1, H-6); 7.63 (1H, dd, 3J8,7 = 8.0, 3J8,9 = 4.3, H-8); 4.49 (1H, q,
2
2
712

3
3JOCH2,CH3 = 7.1, OCH2); 1.44 (1H, t, JCH3,OCH2 = 7.1, CH3). 13C NMR spectrum (75 MHz, CDCl3): δ, ppm (J, Hz):
3
2
3
164.4 (3JCO,OCH2 = 3.2, JCO,H-2 = 2.2, CO); 151.0 (1J = 181.1, JC-9,H-8 = 3.5, JC-9,H-7 = 7.6, C-9); 150.0 (J = 188.0,
C-2); 147.9 (3JC-4,H-2 = 13.4, 2JC-4,H-5 = 5.8, 3JC-4,H-6 = 1.0, C-4); 145.3 (3JC-10a,H-6 = 6.4, 3JC-10a,H-7 = 5.6, 3JC-10a,H-9 = 10.8,
C-10a); 142.7 (3JC-10b,H-2 = 8.0, JC-10b,H-5 = 5.0, C-10b); 135.9 (J = 163.1, JC-7,H-6 = 4.7, JC-7,H-9 = 5.8, C-7); 129.1
3
3
3
(2JC-6a,H-6 = 2.3, 2JC-6a,H-7 = 1.2, JC-6a,H-5 = 9.5, JC-6a,H-8 = 7.4, C-6a); 128.2 (1J = 162.8, JC-6,H-7 = 5.1, C-6); 126.5
3
3
3
(3JC-4a,H-6 = 9.4, C-4a); 125.1 (2JC-3,H-2 = 8.1, C-3); 124.0 (1J = 164.9, 3JC-8,H-9 = 9.1, C-8); 122.4 (1J = 165.8, C-5); 62.2
(1J = 148.5, JOCH2,CH3 = 4.4, OCH2); 14.1 (1J = 127.4, JCH3,OCH2 = 2.6, CH3). 15N NMR spectrum (50 MHz,
DMSO-d6): δ, ppm: −75.6 (N-10); −82.4 (N-1). Mass spectrum, m/z (Irel, %): 288 [M]+ (22), 286 [M]+ (60), 243 (20),
242 (25), 241 (100), 213 (82), 178 (35), 151 (61), 75 (24).
2
2
4-Chloro-1,10-phenanthroline-3-carboxylic acid (5). Compound 4 (573 mg, 2 mmol) was dissolved in
DME (30 ml), and aqueous KOH (40%, 30 ml) was added. The reaction mixture was stirred overnight. Then, the
formed precipitate was filtered off, treated with 1N HCl, and filtered off again and dried to obtain 358 mg of the
beige mixture of compounds 5 and 6; mp 310–314°C. During the recording of the NMR spectra in DMSO-d6,
1
hydrolysis of compound 5 was observed. Compound 5: H NMR spectrum (500 MHz, DMSO-d6), δ, ppm (J,
Hz): 9.44 (1H, s, H-2), 9.38 (1H, m, H-9), 9.36 (1H, m, H-7), 8.40 (1H, m, H-8), 8.58 (1H, d, 3J5,6 = 9.3, H-5),
3
8.48 (1H, d, J5,6 = 9.3, H-6), 4.82 (1H, br. s, COOH). Mass spectrum, m/z (Irel, %): 260 [M]+ (18), 258 [M]+
(38), 241 (38), 196 (83), 168 (87), 140 (37), 111 (26), 98 (43), 97 (30), 81 (33), 69 (71), 57 (66), 55 (71), 45
(58), 43 (100), 41 (62). HRMS (EI, 70 eV), m/z: Found: 258.0202 [M]+. C13H7ClN2O2. Calculated: 258.0196.
1
Compound 6 [13]: H NMR spectrum (500 MHz, DMSO-d6), δ, ppm (J, Hz): 13.84 (2H, 2s, NH); 9.14
3
4
3
4
(1H, dd, J9,8 = 4.3, J9,7 = 1.6, H-9); 8.73 (1H, s, H-2); 8.62 (1H, dd, J7,8 = 8.3, J7,9 = 1.6, H-7); 8.24 (1H, d,
3J5,6 = 8.9, H-5); 8.03 (1H, d, 3J6,5 = 8.9, H-6); 7.91 (1H, dd, 3J8,7 = 8.3, 3J8,9 = 4.3, H-8); 4.82 (1H, br. s, COOH).
13C NMR spectrum (125 MHz, DMSO-d6), δ, ppm (J, Hz): 177.9 (3JC-4,H-2 = 6.4, JC-4,H-5 = 3.3, C-4); 166.2
3
(3JCO,H-2 = 3.5, CO); 150.7 (1J = 181.7, JC-9,H-8 = 3.6, JC-9,H-7 = 7.6, C-9); 143.8 (1J = 182.8, C-2); 138.4
2
3
(3JC-10a,H-9 = 12.3, JC-10a,H-6 = 6.5, JC-10a,H-7 = 5.8, JC-10a,H-5 = 1.0, C-10a); 137.1 (3JC-10b,H-5 = 7.0, C-10b); 137.0
3
3
4
(1J = 166.6, JC-7,H-9 = 6.1, JC-7,H-6 = 4.5, C-7); 129.7 (2JC-6a,H-6 = 2.4, 3JC-6a,H-5 = 9.6, JC-6a,H-8 = 7.5, C-6a); 125.4
(1J = 167.5, 3JC-6,H-7 = 4.6, C-6); 125.2 (1J = 166.9, 2JC-8,H-9 = 8.9, C-8); 123.6 (3JC-4a,H-6 = 8.8, C-4a); 121.3 (1J = 168.2,
C-5); 110.5 (C-3). 15N NMR spectrum (50 MHz, DMSO-d6), δ, ppm: −83.4 (N-10); −236.9 (N-1).
4-Chloro-1,10-phenanthroline-3-carbonyl chloride (7) [13]. The crude mixture resulting from
saponification of ester 4 (compound 5 or a mixture of compounds 5 and 6) was suspended in SOCl2 (15 ml), and
DMF (3 drops) was added. The reaction mixture was refluxed for 3 h. After cooling to room temperature, the
solvent was evaporated under reduced pressure to give the crude acid chloride 7, which was used in the
following acylation reaction without further purification.
3
3
3
8-Methyl-10-phenylpyrazolo[4',3':5,6]pyrano[3,2-c][1,10]phenanthrolin-7(10H)-one
(10).
Under
stirring, to a suspension of 3-methyl-1-phenyl-2-pyrazolin-5-one (8) (174 mg, 1 mmol) and Ca(OH)2 (148 mg,
2 mmol) in dioxane (1 ml) was added the crude acid chloride 7 (277 mg, 1 mmol) in dioxane (2 ml) and the
mixture was refluxed for 3 h. After cooling to room temperature, 2N HCl (3 ml) and H2O (5 ml) were added.
After 20 h, the precipitate was filtered off and washed with H2O to obtain the target compound 10. An analytical
sample was recrystallized from ethanol and DMF. Yield 151 mg (40%); beige–pale brownish powder;
mp > 340°C. IR spectrum (KBr), ν, cm−1: 1664. 1H NMR spectrum (500 MHz, DMSO-d6): δ, ppm (J, Hz): 9.70
3
4
3
4
(1H, s, H-6); 9.21 (1H, dd, J3,2 = 4.2, J3,1 = 1.4, H-3); 8.63 (1H, dd, J1,2 =8.1, J1,3 = 1.4, H-1); 8.38 (1H, d,
3J12,13 = 9.1, H-12); 8.29 (1H, d, 3J13,12 = 9.1, H-13); 8.04 (2H, m, H-2,6, Ph); 7.89 (1H, dd, 3J2,3 = 4.2, 3J2,1 = 8.1,
H-2); 7.74 (2H, m, H-3,5, Ph); 7.55 (1H, m, H-4, Ph); 2.65 (3H, s, CH3). H NMR spectrum (500 MHz,
pyridine-d5): δ, ppm (J, Hz): 10.30 (1H, s, H-6); 9.36 (1H, dd, J3,2 = 4.1, J3,1 = 1.7, H-3); 8.47 (1H, d,
3J12,13 = 9.0, H-12); 8.33 (1H, dd, 3J1,2 = 8.1, 4J1,3 = 1.7, H-1); 8.23 (2H, m, H-2,6, Ph); 8.06 (1H, d, 3J13,12 = 9.0,
H-13); 7.66 (2H, m, H-3,5, Ph); 7.65 (1H, dd, J2,3 = 4.1, J2,1 = 8.1, H-2); 7.46 (1H, m, H-4, Ph); 2.81 (3H, s,
CH3). 13C NMR spectrum (125 MHz, pyridine-d5): δ, ppm: 172.5 (C-7); 156.8 (C-11a); 151.3 (C-3); 149.2 (C-4b);
1
3
4
3
3
713

148.4 (C-6); 147.6 (C-8); 145.5 (C-4a); 137.3 (C-1, Ph); 136.3 (C-1); 130.0 (C-3,5, Ph); 129.9 (C-13a); 128.7
(C-13); 128.0 (C-4, Ph); 124.3 (C-2); 121.7 (C-2,6, Ph); 119.0 (C-12); 118.6 (C-11b); 116.2 (C-6a); 106.5 (C-7a);
13.9 (CH3); C-10a was not found. Mass spectrum, m/z (Irel, %): 379 [M + 1]+ (15), 378 [M]+ (100), 189 (12), 155
(13), 91 (24), 77 (63), 51 (29). HRMS (EI, 70 eV), m/z: Found: 378.1120 [M]+. C23H14N4O2. Calculated:
378.1117. Found, %: C 71.88; H 3.91; N 14.26. C23H14N4O2 · ⅓H2O. Calculated, %: C 71.87; H 3.85; N 14.58.
The authors are grateful to Dr. L. Jirovetz for recording the mass spectra.
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