Nitrosylation of 3a-substituted 2,3,3a,4-tetrahydro-1h-benzo[d]-pyrrolo[1, 2-a]imidazol-1-ones

Full text of DOI:10.1007/s10593-011-0790-4

Chemistry of Heterocyclic Compounds, Vol. 47, No. 4, July 2011 (Russian original Vol. 47, No. 4, April, 2011)
NITROSYLATION OF 3a-SUBSTITUTED
2,3,3a,4-TETRAHYDRO-1H-BENZO[d]-
PYRROLO[1,2-a]IMIDAZOL-1-ONES
V. S. Grinev1* and A. Yu. Yegorova2
Keywords: 2,3,3a,4-tetrahydro-1H-benzo[d]pyrrolo[1,2-a]imidazol-1-ones, intramolecular NO+ cation
migration, nitrosylation, Fischer-Hepp rearrangement.
We report the nitrosylation of previously synthesized 3a-substituted 2,3,3a,4-tetrahydro-1H-benzo[d]-
pyrrolo[1,2-a]imidazol-1-ones 1a,b in the reaction of 5R-3H-furan-2-ones with 1,2-diaminobenzene [1]. The
nitrosylation reaction was carried out at 0–5°C in aqueous acetonitrile. Nitrous acid was generated in situ and
introduced directly to react with the substrate. The crystalline products have a color characteristic for nitroso
compounds.
+
NO
R
R
R
N
ON
H
O
O
O
N
N
HN
HN
N
+
+
NO
N
O
1a,b
2a,b
1, 2 a R = Ph, b R = 4-MeC6H4
__________
*To whom correspondence should be addressed; e-mail: grinev@ibppm.sgu.ru.
1 Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13
Entuziastov Pr., Saratov 410049, Russia.
2N. G. Chernyshevsky Saratov State University, 83 Astrakhanskaya St., Saratov 410001, Russia;
e-mail: yegorovaay@mail.ru.
__________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 624–625, April, 2011. Original
article submitted March 13, 2011.
0009-3122/11/4704-0517©2011 Springer Science+Business Media, Inc.
517

Since imidazolones 1a,b possess two reaction sites capable of reacting with electrophilic reagents, we
could expect the formation of products of N-nitrosylation and/or C-nitrosylation.
The nitrosonium cation is a weak electrophile and, thus, attack at the secondary amino group in imida-
zolones 1a,b is more likely and would obey kinetic control. However, the NMR spectral data indicate the
formation of compounds 2a,b, which were identified as 7-nitroso-3a-R-2,3,3a,4-tetrahydro-1H-benzo[d]pyr-
rolo[1,2-a]imidazol-1-ones. The formation of these nitroso products is possible through a Fischer-Hepp
rearrangement, which proceeds under acid catalysis conditions as an intramolecular migration of the NO+ cation,
leading to the thermodynamically more stable C-nitrosylation products 2a,b.
1
The H NMR spectra were taken on a Varian-400 spectrometer at 400 MHz at 20–25°C in CDCl3 with
TMS as internal standard.
7-Nitroso-3a-phenyl-2,3,3a,4-tetrahydro-1H-benzo[d]pyrrolo[1,2-a]imidazol-1-one (2a). Excess
concentrated sulfuric acid was added to a solution of NaNO2 (0.07 g, 1 mmol) in cold water (3–5 ml), followed
by a solution of compound 1a (0.25 g, 1 mmol) in 4:1 acetonitrile-water (10 ml) and then water (50 ml). The
mixture was stirred for 2 h at room temperature. The precipitate was filtered off and washed with water to give
1
0.21 g (75%) pale-yellow crystalline nitroso derivative 2a; mp 96–98°C. H NMR spectrum, , ppm (J, Hz):
1.62 (1H, br.s, NH); 3.61 (2H, t, J = 6.2, H-2); 3.88 (2H, t, J = 6.2, H-3); 7.47 (1H, d, J = 2.0, H-8); 7.49–7.65
(5H, m, C6H5); 8.12 (1H, d, J = 8.0, H-6); 8.25 (1H, d, J = 8.0, H-5). Found, %: C 69.00; H 5.15; N 15.23.
C16H13N3O2 .Calculated, %: C 68.81; H 4.69; N 15.05.
3a-(4-Methylphenyl)-7-nitroso-2,3,3a,4-tetrahydro-1H-benzo[d]pyrrolo[1,2-a]imidazol-1-one (2b)
was obtained in 73% yield analogously from compound 1b (0.26 g, 1 mmol) and NaNO2 (0.07 g, 1 mmol);
mp 120–122°C. 1H NMR spectrum, , ppm (J, Hz): 1.68 (1H, br.s, NH); 2.26 (3H, s, CH3); 3.24 (2H, t, J = 6.0,
H-2); 3.44 (2H, t, J = 6.2, H-3); 7.21, 7.39 (4H, d, J = 8.0, p-Tol); 7.47 (1H, d, J = 2.0, H-8); 8.12 (1H, d,
J = 8.0, H-6); 8.25 (1H, d, J = 8.0, H-5). Found, %: C 69.49; H 5.06; N 14.69. C17H15N3O2. Calculated, %:
C 69.61; H 5.15; N 14.33.
This work was carried out with the financial support of the Russian Basic Research Fund, Grant 10-03-
00640-a.
REFERENCES
1.
V. S. Grinev, O. A. Amal'chieva, A. Yu. Yegorova, and E. V. Lyubun', Zh. Org. Khim., 46, 1376 (2010).
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