3-Azidothieno[2,3-b]pyridine Thermolysis as a Route to Novel peri-Annelated Heterocyclic Derivatives - Benzo(furo)thieno[2,3,4-ij]-2,7-naphthyridines

Article abstract of DOI:10.1055/s-0034-1379983

Synthesis of novel benzo(furo)thieno[2,3,4-ij]-2,7-naphthyridines based on alkyl(aryl) 3-azido-4-aryl(furyl)thieno[2,3-b]pyridine-2-carboxylate thermolysis is elaborated. The structures of the synthesized materials were assigned by their NMR, IR, and MS analysis.

Full text of DOI:10.1055/s-0034-1379983

SYNLETT
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5
2
1
4
1
4
3
7
-
2
0
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©
Georg Thieme Verlag Stuttgart · New York
2015, 26, 755–758
755
letter
Synlett
V. K. Vasilin et al.
Letter
3
-Azidothieno[2,3-b]pyridine Thermolysis as a Route to Novel
peri-Annelated Heterocyclic Derivatives – Benzo(furo)thieno
2,3,4-ij]-2,7-naphthyridines
[
Vladimir K. Vasilin*
Eugeniya A. Kanishcheva
Tatyana A. Stroganova
Gennady D. Krapivin
A
A
NH
S
N3
R2
reflux
R2
O
O
O
O
C6H5Cl
Kuban State Technological University, Moskovskaya st. 2,
Krasnodar 350072, Russian Federation
vasvk@mail.ru
S
N
N
R1
R1
A = Ar, 5-methylfur-2-yl
57–67%
Received: 28.11.2014
Accepted: 17.12.2014
Published online: 29.01.2015
DOI: 10.1055/s-0034-1379983; Art ID: st-2014-d0982-l
Subsequently, we have been interested in the construc-
tion of new heterocyclic systems by the thermolysis of 3-
azidothieno[2,3-b]pyridines containing suitable for intra-
molecylar cyclization aryl substituents at position 4 of the
thienopyridine framework. In our opinion, such a cycliza-
tion could lead us to construct new polycyclic thienopyri-
dines fused with six-membered azaheterocycle. A similar
ring formation was used earlier in pyridoacridine alkaloid
Abstract Synthesis of novel benzo(furo)thieno[2,3,4-ij]-2,7-naphthyri-
dines based on alkyl(aryl) 3-azido-4-aryl(furyl)thieno[2,3-b]pyridine-2-
carboxylate thermolysis is elaborated. The structures of the synthesized
materials were assigned by their NMR, IR, and MS analysis.
Key words thieno[2,3-b]pyridine, azides, fused-ring systems, ther-
molysis, nitrene, cyclization, naphthyridine
4–7,11
syntheses.
Herein, we present a synthesis of novel peri-annelated
thienopyridine derivatives – benzo(furo)thieno[2,3,4-ij]-
2,7-naphthyridines – by azido group thermolysis in alkyl-4-
aryl(furyl)-3-azidothieno[2,3-b]pyridine carboxylates 1 fol-
lowed by an intramolecular cyclization of the intermediate
nitrene.
The chemistry of azides has attracted the attention of
chemists for many years. The thermal and photochemical
reactions of aryl azides are widely used in synthetic organic
1
chemistry. Thus, a cyclization of o-azidoarene derivatives
by photolysis or thermolysis has been developed into a
powerful synthetic method for the construction of pyr-
The starting materials 1a–e were prepared from the
corresponding 3-cyanopyridine-2-thiones 2 and alkyl(aryl)
chloroacetates 3 using the synthetic sequence depicted in
Scheme 1.1
1
a,b,2
3
role
and azepine ring. This methodology is widely used
2,13
for syntheses of such natural compounds as pyridoacridine
4
alkaloids and their analogues, cystodytin J, diplamine and
Thermolysis of the compounds 1a–e was carried out in
refluxing in chlorobenzene (Scheme 2) to give compounds
shermilamine B, the kuanoniamines and dercitins,6
5
7
14
norsegoline, and the indoloisoquinoline alkaloids crypto-
5a–e as the major products in 57–67% yields.
8
tackieine and cryptosanguinolentine.
For compounds 1d,e (R = Ar) two ways for an intramo-
lecular attack of nitrene derived from azide decomposition
(Scheme 2) were possible: Path a involves nitrene attack
onto the aryl substituent in position 4 of the thieno[2,3-
b]pyridine core to give the thieno[2,3,4-ij]-2,7-naphthyri-
dine framework. Followong path b, the nitrene could attack
the aryl ring of the ester group to yield an oxazepine. It was
found that path a was preferred, and naphthyridines 5d,e
were isolated as the major products. Probably, formation of
the 18π-electron peri-annelated aromatic heterocyclic sys-
tem may be responsible for such direction of the cycliza-
tion.
In the context of our studies on the application of thie-
no[2,3-b]pyridines for the preparation of new fused hetero-
cyclic systems bearing the thienopyridine unit, earlier we
have described syntheses of novel pyrido[3′,2′:4,5]thie-
9
no[3,2-b]indoles
and
6H-pyrido[3′,2′:4,5]thieno[3,2-
10
b][1,5]benzodiazepine-6-ones, based on thermal decom-
position of the corresponding 3-azidothieno[2,3-b]pyri-
dines. It should be noted that in these examples an inter-
molecular attack of a nitrene derived from thermolysis of
an azido group was directed onto the subsituent at position
2
of the thienopyridine framework.
©
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V. K. Vasilin et al.
Letter
A
A
NH2
N
R2
O
O
O
KOH
DMF
+
Cl
R2
S
N
H
S
O
N
3
R1
R1
2
4a–e
1) NaNO2, H2SO4
, 4 a A = Ph, R1 = H, R = Et [1a (75%), 4a (59%)];
2
2) NaN3
1
1
2
b A = 4-MeC6H4, R = Me, R = Am [1b (76%), 4b (63%)];
c A = 5-methylfur-2-yl, R = H, R2 = Et [1c (79%), 4c (61%)];
1
A
d A = Ph, R1 = H, R2 = Ph [1d (84%), 4d (58%)];
e A = 4-MeOC6H4, R1 = H, R2 = 4-MeC6H4 [1e (80%), 4e (68%)]
N3
S
O
O
R2
N
R
1a–e
Scheme 1
The structure of the products 5 was assigned consider-
ation of their mass, IR, H NMR, and C NMR spectra. In the
H NMR spectra of 1a–e, singlets at δ = 9.97–10.75 ppm cor-
responded to NH signals.
References and Notes
1
13
(1) (a) Moses, J. E.; Moorhouse, A. D. Chem. Soc. Rev. 2007, 36, 1249.
1
(
(
b) Gritsan, N. P.; Platz, M. S. Chem. Rev. 2006, 106, 3844.
c) Braese, S.; Gil, C.; Knepper, K.; Zimmermann, V. Angew.
In conclusion, several derivatives of novel benzo(furo)-
thieno[2,3,4-ij]-2,7-naphthyridines have been synthesized
by thermolysis of alkyl(aryl) 3-azidothieno[2,3-b]pyridine-
Chem. Int. Ed. 2005, 44, 5188. (d) Scriven, E. F. V.; Turnbull, K.
Chem. Rev. 1988, 88, 297. (e) Gritsan, N. P.; Pritchina, E. A. Russ.
Chem. Rev. 1992, 61, 500. (f) Schuster, G. B.; Platz, M. S. Adv.
Photochem. 1992, 69. (g) Smith, P. A. S. In Azides and Nitrenes,
Reactivity and Utility; Academic Press: New York, 1984, 95.
2-carboxylates containing an aryl or heteroaryl substituent
at position 4 of the thienopyridine core. These results
demonstrate that this method will provide a useful tool for
the synthesis of novel peri-annelated aromatic tetracyclic
derivatives of thieno[2,3-b]pyridines.
(
h) Driver, T. G. Org. Biomol. Chem. 2010, 8, 3831.
2) (a) Mamidyala, S. K.; Cooper, M. A. Сhem. Commun. 2013, 49,
407. (b) Takeuchi, H.; Maeda, M.; Mitani, M.; Koyama, K. J.
(
8
Chem. Soc., Perkin Trans. 1 1987, 57. (c) Shi, Z.; Ren, Y.; Li, B.; Lu,
S.; Zhang, W. Chem. Commun. 2010, 46, 3973. (d) Dang, H. V.;
Knobloch, B.; Habib, N. S.; Kappe, T.; Stadlbauer, W. J. Hetero-
cycl. Chem. 2005, 42, 85. (e) Riedl, Z.; Monsieurs, K.;
Krajsovszky, G.; Dunkel, P.; Maes, B. U. W.; Tapolcsányi, P.;
Egyed, O.; Boros, S.; Mátyus, P.; Pieters, L.; Lemiére, G. L. F.;
Hajos, G. Tetrahedron 2006, 62, 121. (f) Stockmann, V.; Bakke, J.
M.; Bruheim, P.; Fiksdahl, A. Tetrahedron 2009, 65, 3668.
Acknowledgment
The study was supported by The Ministry of Education and Science of
the Russian Federation; Project 2515.
A
A
NH
S
HN
S
path b
path a
1a–e
O
O
R2
O
C6H5Cl
reflux
R2 = Ph
N
O
N
R1
R1
5
5
5
5
5
a 57%
b 59%
c 63%
d 60%
e 67%
Scheme 2
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 755–758

7
57
Synlett
V. K. Vasilin et al.
Letter
(
3) (a) Hollywood, F.; Nay, B.; Scriven, E. F. V.; Suschitzky, H.; Khan,
Z. U.; Hull, R. J. Chem. Soc., Perkin Trans. 1982, 421.
b) Broggini, G.; Molteni, G.; Zecchi, G. Synthesis 1995, 647.
c) Beccalli, E.; Broggini, G.; Paladino, G.; Pilati, T.; Pontremoli,
(17), 44 (13), 43 (37). Anal. Calcd for C21H18N O S: C, 66.65; H,
4.79; N, 7.40. Found: C, 66.80; H, 4.85; N, 7.51.
Phenyl 3-Amino-4,6-diphenylthieno[2,3-b]pyridine-2-car-
boxylate (4d)
2
3
1
(
(
G. Tetrahedron: Asymmetry 2004, 15, 687. (d) Broggini, G.;
Garanti, L.; Molteni, G.; Pilati, T. Tetrahedron: Asymmetry 2001,
Yield 58%; bright yellow crystals; mp 178–179 °C. IR (ATR):
–1 1
3493 (asym. NH ), 3356 (sym. NH ), 1686 (C=O) cm
.
H NMR
2
2
12, 1201. (e) Santagada, V.; Perissutti, E.; Fiorino, F.; Vivenzio,
(400 MHz, DMSO-d ): δ = 5.95 (2 H, br s, NH ), 7.21 (2 H, d, J =
6
2
B.; Caliendo, G. Tetrahedron Lett. 2001, 42, 2397.
8.1 Hz, 2,6-H OPh), 7.27 (1 H, t, J = 7.3 Hz, 4-H OPh), 7.38–7.46
(4) Ali, N. M.; Chattopadhyay, Sh. K.; McKillop, A.; Perret-Gentil, R.
M.; Ozturk, T.; Rebelo, R. A. Chem. Soc., Chem. Commun. 1992,
(2 H, m, HPh), 7.47–7.53 (3 H, m, HPh), 7.58–7.64 (5 H, m, HPh),
7.79 (1 H, s, HPy), 8.21 (2 H, dd, J = 7.7, 2.5 Hz, HPh). C NMR (100
13
1453.
MHz, DMSO-d ): δ = 93.7, 118.8, 120.4, 122.5 (2 C), 126.3, 127.8
6
(
(
(
(
5) Ciufolini, M. A.; Shen, Y.-C. Tetrahedron Lett. 1995, 36, 4709.
6) Bishop, M. J.; Ciufolini, M. A. J. Am. Chem. Soc. 1992, 114, 10081.
7) Dunn, S. H.; McKillop, A. J. Chem. Soc., Perkin Trans. 1 1993, 879.
8) (a) Fresneda, P. M.; Molina, P.; Delgado, S. Tetrahedron 2001, 57,
(2 C), 129,0 (2 C), 129.4 (2 C), 129.5 (2 C), 129.8, 129.9 (2 C),
130.6, 136.6, 137.6, 148.8, 149.7, 150.6, 157.4, 161.8, 163.2. MS
(EI, 70 eV): m/z (%) = 423 (16) [M + 1], 422 (90) [M] , 331 (12),
+
330 (24), 329 (100), 301 (18), 300 (35), 299 (11), 241 (5), 227
(4), 224 (4). Anal. Calcd for C26H18N O S: C, 73.91; H, 4.29; N,
6197. (b) Fresneda, P. M.; Molina, P.; Delgado, S. Tetrahedron
2
2
Lett. 1999, 40, 7275.
6.63. Found: C, 73.98; H, 4.38; N, 6.54.
(
9) Kanishcheva, E. A.; Vasilin, V. K.; Kasimova, D. R.; Stroganova,
(13) Alkyl(aryl) 3-Azidothieno[2,3-b]pyridine-2-carboxylates 1a–
e; General Procedure
T. A.; Krapivin, G. D. Chem. Heterocycl. Compd. 2013, 48, 1883.
(
10) Kanishcheva, E. A.; Vasilin, V. K.; Stroganova, T. A.; Krapivin,
To a stirred solution of compound 4a–e (10 mmol) in AcOH (75
mL) H SO (10 mmol, 0.52 mL) was added, and the mixture was
G. D. Chem. Heterocycl. Compd. 2013, 49, 1387.
2
4
(
11) Gellerman, G.; Rudi, A.; Kashman, Y. Tetrahedron Lett. 1992, 33,
577.
cooled to 7–10 °C. After that a solution of NaNO (15 mmol, 1.02
2
5
g) in H O (2 mL) was added, and the mixture was stirred for 15
2
(12) Alkyl(aryl) 3-Aminothieno[2,3-b]pyridine-2-carboxylates 4;
General Procedure
min. The excess HNO was neutralized with urea, and a solution
2
of NaN3 (15 mmol, 0.96 g) in H O (2 mL) was added. After 30
2
To solution of the requisite pyridine-2-thione (2, 2 mmol) in
DMF (20 mL) and aq KOH (10%, 11.2 mL, 2 mmol) was added
the alkylating agent 3 (2 mmol), and the resulted mixture was
stirred for 30–40 min until a solid formed. The precipitate was
filtered off, washed with cold EtOH (7 mL), and air-dried. Then
the solid was dissolved in DMF (10 mL), another portion of KOH
solution (5.6 mL, 1 mmol) was added, and the mixture was
stirred for a further 0.5–1 h until a yellow precipitate formed.
The crystals were filtered off, washed with cold EtOH, and
dried to yield 3-aminothieno[2,3-b]pyridines 4a–e in 58–68%
yields.
min the mixture was poured into 200 mL of cold H O, the resul-
2
tant solid was filtered off, washed thoroughly with H O, and
2
dried over P O to give azides 1a–e in 75–84% yield. Due to their
2
5
instability, compounds 1 were used for the next stage without
additional purification.
Ethyl 3-Azido-4,6-diphenylthieno[2,3-b]pyridine-2-carbox-
ylate (1a)
Yield 75%; bright yellow powder; mp (decomp.) 165–166 °C. IR
–1
(ATR): 2125 (N ), 1703 (C=O) cm
.
3
Ethyl
3-Azido-4-(5-methyl-2-furyl)-6-phenyl-thieno[2,3-
b]pyridine-2-carboxylate (1c)
Ethyl
boxylate (4a)
3-Amino-4,6-diphenyl-thieno[2,3-b]pyridine-2-car-
Yield 79%; dark red powder; mp (decomp.) 149–150 °C. IR
–1
(ATR): 2119 (N ), 1696 (C=O) cm .
3
Yield 59%; bright yellow powder; mp 154–155 °C. IR (ATR):
Phenyl
boxylate (1d)
3-Azido-4,6-diphenylthieno[2,3-b]pyridine-2-car-
–1 1
3
493 (asym. NH ), 3355 (sym. NH ), 1674 (C=O) cm
.
H NMR
2
2
(
(
400 MHz, DMSO-d ): δ = 1.27 (3 H, t, J = 7.2 Hz, CH CH O), 4.24
Yield 84%; orange powder; mp (decomp.) 184–185 °C. IR (ATR):
6
3
2
–1
2 H, q, J = 7.2 Hz, CH CH O), 5.78 (2 H, br s, NH ), 7.45–7.53 (3
2122 (N ), 1709 (C=O) cm .
3
2
2
3
H, m, HPh), 7.58 (5 H, s, HPh), 7.75 (1 H, s, HPy), 8.15–8.22 (2 H, m,
(14) Thermolysis of Alkyl(aryl) 3-Azidothieno[2,3-b]pyridine-2-
carboxylates 1; General Procedure
13
HPh). C NMR (100 MHz, DMSO-d ): δ = 14.8, 60.6, 95.4, 118.6,
6
1
20.7, 127.7 (2 C), 129.1 (2 C), 139.32 (2 C), 139.34 (2 C), 129.8,
A solution of azide 1 (3 mmol) in chlorobenzene (100 mL) was
heated to reflux for 30 min until termination of gas evolution
and full consumption of the initial compound (TLC control).
Next, the mixture was evaporated under reduced pressure to
1/3 of the initial volume, the hot solution was diluted with PE
(10–15 mL) and left to allow crystallization. The crystals formed
were filtered off, washed with PE and recrystallized from DMF
to give products 5a–e in 57–67% yields.
130.4, 136.8, 137.7, 147.9, 148.5, 156.8, 161.4, 164.8. MS (EI, 70
+
eV): m/z (%) = 375 (26) [M + 1], 374 (100) [M] , 345 (14), 327
(22), 326 (44), 301 (17), 300 (10), 299 (16), 298 (53), 59 (10), 58
(11), 43 (41), 42 (26). Anal. Calcd for C22H18N O S: C, 70.57; H,
2
2
4.85; N, 7.48. Found: C, 70.64; H, 4.76; N, 7.50.
Ethyl
3-Amino-4-(5-methyl-2-furyl)-6-phenyl-thieno[2,3-
b]pyridine-2-carboxylate (4c)
Yield 61%; yellow powder; mp 140–141 °C. IR (ATR): 3454
Ethyl 2-Phenyl-6H-benzo[c]thieno[2,3,4-ij]-2,7-naphthyri-
dine-5-carboxylate (5a)
–1 1
(
asym. NH ), 3344 (sym. NH ), 1666 (C=O) cm
.
H NMR (400
2
2
MHz, DMSO-d ): δ = 1.30 (3 H, t, J = 7.1 Hz, CH CH O), 2.44 (3 H,
Yield 57%; yellow crystals; mp 202–203 °C. IR (ATR): 3317 (NH),
1645, 1618, 1594, 1536, 1458, 1415, 1289, 1274, 1223, 1157,
6
3
2
s, CH -Fur), 4.25 (2 H, q, J = 7.1 Hz, CH CH O), 6.43 (1 H, d, J = 3.6
3
3
2
–1 1
Hz, 4-H Fur), 6.84 (2 H, br s, NH ), 7.24 (1 H, d, J = 3.6 Hz, 3-H
1075, 1024, 743 cm . H NMR (400 MHz, DMSO-d ): δ = 1.34 (3
2
6
Fur), 7.45–7.55 (3 H, m, HPh), 7.97 (1 H, s, HPy), 8.18 (2 H, d, J =
H, t, J = 6.9, CH CH O), 4.32 (2 H, q, J = 6.9 Hz, CH CH O), 7.13 (1
3
2
3
2
13
8
9
1
.1, HPh). C NMR (100 MHz, DMSO-d ): δ = 14.0, 14.9, 60.7,
4.9, 109.7, 115.6, 115.9, 118.7, 127.6 (2 C), 129.3 (2 C), 130.5,
H, dd, J = 8.1, 8.1, 1.1 Hz, H-9), 7.44 (1 H, dd, J = 8.1, 8.2 Hz, H-8),
7.48 (2 H, dd, J = 8.1, 8.3 Hz, 3,5-H Ph), 7.51 (1 H, dd, J = 8.3, 1.7
Hz, 4-H Ph), 7.57 (1 H, dd, J = 8.2, 1.1 Hz, H-7), 8.11 (1 H, s, H-1),
8.16 (2 H, dd, J = 8.1, 1.7 Hz, 2,6-H Ph), 8.24 (1 H, d, J = 8.1 Hz, H-
6
36.2, 137.6, 148.2, 148.7, 155.6, 156.9, 162.5, 165.0. MS (EI, 70
+
eV): m/z (%) = 379 (31) [M + 1], 378 (100) [M] , 350 (15), 332
13
(19), 331 (48), 306 (11), 262 (15), 261 (13), 189 (4), 152 (4), 53
10), 9.97 (1 H, s, NH). C NMR (100 MHz, DMSO-d ): δ = 14.9,
6
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V. K. Vasilin et al.
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6
1
1
0.5, 92.0, 106.2, 117.2, 118.4, 122.7, 123.6, 125.3, 127.8 (2 C),
29.0 (2 C), 130.0, 132.5, 139.0, 139.4, 139.5, 140.2, 160.3,
(24), 102 (10), 92 (20), 91 (59), 77 (13), 76 (39), 51 (16), 44 (13),
43 (33). Anal. Calcd for C21H16N O S: C, 67.00; H, 4.28; N, 7.44.
Found: C, 67.05; H, 4.36; N, 7.39.
Phenyl 2-Phenyl-6H-benzo[c]thieno[2,3,4-ij]-2,7-naphthyri-
dine-5-carboxylate (5d)
2
3
61.3, 163.6. MS (EI, 70 eV): m/z (%) = 373 (8) [M + 1], 372 (30)
+
[
M] , 371 (15), 327 (10), 326 (32), 300 (36), 299 (31), 298 (100),
297 (20), 254 (10), 252 (10), 239 (17), 226 (10), 148 (10), 43
(
36). Anal. Calcd for C22H16N O S: C, 70.95; H, 4.33; N, 7.52.
Yield 60%; yellow crystals; mp 214–216 °C. IR (ATR): 3375,
1665, 1618, 1594, 1559, 1532, 1481, 1453, 1391, 1294, 1278,
2
2
Found: C, 71.08; H, 4.39; N, 7.44.
Ethyl 8-Methyl-2-phenyl-6H-furo[3,2-c]thieno[2,3,4-ij]-2,7-
naphthyridine-5-carboxylate (5c)
–1 1
1196, 1165, 1141, 1044, 747 cm
d ): δ = 7.17 (1 H, t, J = 7.1 Hz, 4-H OPh), 7.23–7.38 (3 H, m, H ),
. H NMR (400 MHz, DMSO-
6
Ar
Yield 63%; yellow crystals; mp 231–232 °C. IR (ATR): 3308 (NH),
7.40–7.58 (6 H, m, H ), 7.73 (1 H, d, J = 8.3 Hz, H-7), 8.24 (2 H, d,
Ar
1
633, 1601, 1538, 1415, 1367, 1266, 1239, 1165, 1083, 954, 766
J = 6.7, 2,6-H OPh), 8.29 (1 H, s, H-1), 8.57 (1 H, d, J = 7.9 Hz, H-
–1
13
cm . 1H NMR (400 MHz, DMSO-d ): δ = 1.27 (3 H, t, J = 7.2 Hz,
10), 10.63 (1 H, s, NH). C NMR (100 MHz, DMSO-d ): δ = 106.4,
6
6
CH CH ), 2.30 (3 H, s, CH -Fur), 4.21 (2 H, q, J = 7.2 Hz, CH CH ),
117.2, 118.7, 122.7 (2 C), 123.0, 123.4, 125.5, 126.2, 127.9 (2 C),
129.2 (2 C), 129.8 (2 C), 130.3, 132.7, 136.2, 138.7, 139.7, 140.1,
140.9, 159.9, 160.4, 161.5, 161.7. MS (EI, 70 eV): m/z (%) = 217
2
3
3
2
3
6
8
.37 (1 H, s, 4-HFur), 7.15 (1 H, s, H ), 7.42 (3 H, m, 3,4,5-HPh),
Py
.02 (2 H, m, 2,6-HPh), 10.75 (1 H, s, NH). 13C NMR (100 MHz,
+
+
DMSO-d ): δ = 14.5, 15.0, 60.0, 99.2, 101.3, 123.1, 127.4 (2 C),
(100) [M] ,421 (13) [M + 1], 420 (48) [M] , 328 (25), 327 (100),
301 (11), 299 (53), 298 (16), 265 (10), 255 (10), 229 (10), 228
(13), 218 (10), 140 (13), 107 (14), 94 (57), 80 (15), 58 (19), 52
(10), 43 (33), 42 (14), 40 (17). Anal. Calcd for C26H16N O S: C,
6
1
1
+
28.9 (2 C), 129.2, 129.9, 131.7, 132.4, 136.7, 138.9, 140.8,
58.5, 159.8, 160.7, 163.3. MS (EI, 70 eV): m/z (%) = 377 (15) [M
+
1], 376 (71) [M] , 332 (14), 331 (15), 330 (100), 304 (15), 303
2
2
(
(
53), 302 (81), 301 (11), 261 (7), 259 (7), 258 (10), 242 (5), 216
6), 165 (19), 164 (19), 152 (13), 151 (34), 140 (7), 106 (21), 105
72.27; H, 3.84; N, 6.66. Found: C, 72.34; H, 3.79; N, 6.59.
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 755–758

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