[4+2]-cycloaddition of alkyl vinyl ethers to 3-aroylpyrrolo-[2,1-c][1,4] benzoxazine-1,2,4-triones

Full text of DOI:10.1134/S107042801006031X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 6, p. 941. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © E.E. Stepanova, A.V. Babenysheva, A.N. Maslivets, 2010, published in Zhurnal Organicheskoi Khimii, 2010, Vol. 46, No. 6, p. 940.
SHORT
COMMUNICATIONS
[4+2]-Cycloaddition of Alkyl Vinyl Ethers to 3-Aroylpyrrolo-
[2,1-c][1,4]benzoxazine-1,2,4-triones
E. E. Stepanova, A. V. Babenysheva, and A. N. Maslivets
Perm State University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received December 15, 2009
DOI: 10.1134/S107042801006031X
Reactions of 3-aroylpyrrolo[2,1-c][1,4]benzoxa-
zine-1,2,4-triones with activated alkenes were not
reported previously. We examined the reaction of
3-aroylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones Ia
and Ib with alkyl vinyl ethers IIa and IIb at a ratio of
1:5 in boiling benzene (reaction time 30–60 min) and
obtained representatives of a novel difficultly acces-
sible bridged heterocyclic system, 16-alkoxy-14-aryl-
3,15-dioxa-10-azatetracyclo[8.7.0.01,13.04,9]heptadeca-
4,6,8,13-tetraene-2,11,12-triones IIIa and IIIb.
in 60 ml of anhydrous benzene, and the mixture was
heated under reflux until the original violet color dis-
appeared (40 min). The mixture was then cooled, the
solvent was removed, and the residue was recrystal-
lized from toluene. Yield 74%, mp 238–240°C. IR
spectrum, ν, cm–1: 1794 (C2=O), 1728 (C11=O, C12=O).
1H NMR spectrum, δ, ppm: 1.11 t (3H, CH3, J =
7.2 Hz), 2.38 m (2H, 17-H), 3.71 m (1H, OCH2),
3.82 m (1H, OCH2), 5.78 m (1H, CH), 7.32–7.87 m
(8H, Harom). Found, %: C 55.98; H 3.48; N 3.01.
C22H16BrNO6. Calculated, %: C 56.19; H 3.43; N 2.98.
O
O
16-Butoxy-14-phenyl-3,15-dioxa-10-azatetra-
cyclo[8.7.0.01,13.04,9]heptadeca-4,6,8,13-tetraene-
2,11,12-trione (IIIb). Yield 78%, mp 203–204°C. IR
spectrum, ν, cm–1: 1788 (C2=O), 1725 (C11=O, C12=O).
1H NMR spectrum, δ, ppm: 0.83 t (3H, CH3, J =
7.3 Hz), 1.29 m (2H, CH2Me), 1.46 m (2H, OCH2CH2),
2.40 t (2H, 17-H, J = 3.22 Hz), 3.67 m and 3.78 m (1H
each, OCH2), 5.77 m (1H, CH), 7.33–7.93 m (9H,
Harom). 13C NMR spectrum, δC, ppm: 13.57 (Me), 18.37
(CH2Me), 30.92 (OCH2CH2), 38.88 (C17), 54.46
(OCH2), 69.05 (C1), 100.67 (C16), 102.81 (C13), 116.68–
143.13 (Carom), 159.17 (C11), 160.72 (C2), 166.54 (C14),
175.91 (C12). Found, %: C 68.75; H 5.11; N 3.22.
C24H21NO6. Calculated, %: C 68.73; H 5.05; N 3.34.
O
+
N
OAlk
H2C
Ar
O
O
Ia, Ib
IIa, IIb
OAlk
O
O
O
N
Ar
O
O
IIIa, IIIb
Ar = 4-BrC6H4 (a), Ph (b); Alk = Et (a), Bu (b).
The IR spectra were recorded on an FSM-1201
spectrometer from samples dispersed in mineral oil.
Presumably, compounds IIIa and IIIb were formed
via thermally induced [4+2]-cycloaddition involving
the O=C–C3=C3a conjugated bond system in 3-aroyl-
pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones I and
polarized C=C bond in alkyl vinyl ethers II.
1
The H and 13C NMR spectra were measured on
a Bruker AM-400 instrument at 400 and 100 MHz,
respectively, using DMSO-d6 as solvent and tetra-
methylsilane as internal reference. The purity of the
products was checked by TLC on Silufol plates using
benzene–ethyl acetate (5:1) as eluent.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 08-03-01032).
14-(4-Bromophenyl)-16-ethoxy-3,15-dioxa-10-
azatetracyclo[8.7.0.01,13.04,9]heptadeca-4,6,8,13-
tetraene-2,11,12-trione (IIIa). A solution of 5.0 mmol
of ethyl vinyl ether (IIa) in 5 ml of anhydrous benzene
was added to a solution of 1.0 mmol of compound Ia
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