Spiro-heterocyclization of pyrrolobenzoxazinetriones effected by thiourea

Full text of DOI:10.1134/S107042800710034X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 10, pp. 1577−1578. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © A.V. Babenysheva, V.A. Maslivets, A.N. Maslivets, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 10,
pp. 1579−1580.
SHORT
COMMUNICATIONS
Spiro-Heterocyclization of Pyrrolobenzoxazinetriones
Effected by Thiourea
A. V. Babenysheva, V. A. Maslivets, and A. N. Maslivets
Perm State University, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received April 26, 2007
DOI: 10.1134/S107042800710034X
oxazine ring suffered cleavage at the C4–O5 bond, but
the expected rupture of the ring at the C3a–N10 bond did
not occur under the conditions used.
Reaction of 3-aroyl-2,4-dihydro-1H-pyrrolo[2,1-c]-
[1,4]benzoxazine-1,2,4-triones with thiourea at boiling
in a mixture acetonitrile–DMF was found to give 3-[α-
(5-oxo-2-thioxo-4-imidazolidinylidene)phenacyl]-2H-
1,4-benzoxazin-2-ones [1].
The described reaction is an example of a regio-
selective building up of the previously inaccessible spiro-
bis-heterocyclic system imidazole-4-spiro-2'-pyrrole with
desired substituents variation in several positions of both
heterocycles.
In reaction of 3-methoxycarbonyl- and 3-benzoyl-7-
methyl-2,4-dihydro-1H-pyrrolo[2,1-C][1,4]benzoxazine-
1,2,4-triones I and II with thiourea (III) in a ratio 1:1.5
at boiling in anhydrous benzene for 10–15 min we
obtained in good yield spiro compounds IV and V
respectively. The spectral characteristics of imidazole-
4-spiro-2'-pyrroles IV and V and model indole-3-spiro-
2'-pyrroles whose structure was confirmed by X-ray
analysis are very similar (see Scheme).
Methyl 8-hydroxy-6-(2-hydroxyphenyl)-4,7-dioxo-
2-thioxo-1,3,6-triazaspiro[4,4]non-8-ene-9-carboxy-
late (IV). A solution of 3.6 mmol of compound I and
5.5 mmol of thiourea (III) in 15 ml of anhydrous benzene
was boiled for 15 min (till discoloration), then it was
cooled, and the separated precipitate was filtered off.
Yield 74%, mp 179–181°C (from acetone). IR spectrum,
cm–1: 3330 (NH), 3180 br (OH), 1713 (C=O, COO).
1H NMR spectrum, δ, ppm: 3.68 s (3H, MeO), 6.76–
7.26 m (4H, C6H4), 9.00 s (1H, OHphenol.), 9.23 s (1H,
Evidently in the reaction of pyrrolobenzoxazine-
triones I and II with thiourea the amino groups of the
binucleophile attack in succession the carbon atoms in
positions 3a and 4 of pyrrolobenzoxazinetriones, and the
Scheme.
H2N
NH
S
H2NCSNH2
R
OH
H
R
O
N
O
R
O
N
O
O
N
S
III
COR'
COR'
N
NH
COR'
O
O
OH
O
O
OH
I, II
IV, V
I, IV, R = H, R' = OMe; II, V, R = Me, R' = Ph.
1577

BABENYSHEVA et al.
1578
NH), 9.68 s (1H, NH), 12.30 br.s (1H, OHenol.). 13C NMR
spectrum (DMSO-d6), δ, ppm: 51.43 (CH3O), 84.52
(Cspiro), 109.42–130.53 (CAr), 154.75 (C8), 154.81
(C7=O), 161.65 (COO), 164.12 (C4=O), 183.28 (C=S).
Found, %: C 48.10; H 3.25; N 12.01; S 9.22.
C14H11N3O6S. Calculated, %: C 48.14; H 3.17; N 12.00;
S 9.18.
C20H15N3O5S. Calculated, %: C 58.67; H 3.69; N 10.26;
S 7.83.
IR spectra of compounds obtained were recorded on
a spectrophotometer FMS-1201 from mulls in mineral
oil. 1H and 13C NMR spectra were registered on a spec-
trometer Bruker WP-400 in DMSO-d6, internal reference
TMS. The homogeneity of compounds obtained was
checked by TLC on Silufol plates, eluent ethyl acetate,
development in iodine vapor.
9-Benzoyl-8-hydroxy-6-(2-hydroxy-4-methyl-
phenyl)-2-thioxo-1,3,6-triazaspiro[4,4]non-8-ene-4,7-
dione (V). A solution of 3.0 mmol of compound II and
4.5 mmol of thiourea (III) in 15 ml of anhydrous benzene
was boiled for 10 min (till discoloration), then it was
cooled, and the separated precipitate was filtered off.
Yield 74 %, mp 208–210°C (from acetonitrile). IR
spectrum, cm–1: 3366 (NH), 3152 br (OH), 1709, 1690
br (C=O). 1H NMR spectrum, δ, ppm: 2.25 s (3H, Me),
6.60–7.75 m (8H, Ph + C6H3), 8.85 s (1H, NH), 9.13 s
(1H, OHphenol), 9.43 s (1H, NH), 12.50 br.s (1H, OHenol).
13C NMR spectrum (DMSO-d6), δ, ppm: 20.89 (CH3),
85.20 (Cspiro.), 116.85–140.22 (CAr), 153.05 (C8), 154.45
(C7=O), 164.96 (C4=O), 183.73 (C=S), 188.00 (COPh).
Found, %: C 58.65; H 3.76; N 10.23; S 7.89.
The study was carried out under a financial support
from the Russian Foundation for Basic Research (grant
no. 07-03-96036).
REFERENCES
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 10 2007