[4+2]-cycloaddition of alkyl vinyl ethers to 4,5-diaroyl-1H-pyrrole-2,3- diones

Full text of DOI:10.1134/S1070428009100261

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 10, p. 1571. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © P.S. Silaichev, A.N. Maslivets, 2009, published in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 10, p. 1582.
SHORT
COMMUNICATIONS
[4+2]-Cycloaddition of Alkyl Vinyl Ethers
to 4,5-Diaroyl-1H-pyrrole-2,3-diones
P. S. Silaichev and A. N. Maslivets
Perm State University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received February 4, 2009
DOI: 10.1134/S1070428009100261
1
Reactions of 4,5-diaroyl-1H-pyrrole-2,3-diones
with activated alkenes were not reported previously.
We examined the reaction of 1-aryl-4,5-diaroyl-1H-
pyrrole-2,3-diones Ia and Ib with alkyl vinyl ethers
IIa and IIb at a ratio of 1:1.5 in anhydrous benzene.
The reaction mixtures were heated at 60–70°C until
the bright red color typical of initial pyrrolediones I
disappeared (25–30 min), and the products were
6-alkoxy-7a-aroyl-1,4-diaryl-7,7a-dihydropyrano-
[4,3-b]pyrrole-2,3(1H,6H)-diones IIIa and IIIb. Com-
pounds IIIa and IIIb are likely to be formed via
thermal [4+2]-cycloaddition of the conjugated O=C–
C4=C5 bond system in pyrrolediones Ia and Ib to the
polarized C=C bond in alkyl vinyl ethers IIa and IIb.
152°C. IR spectrum, ν, cm–1: 1725, 1690. H NMR
spectrum, δ, ppm: 1.18 t (3H, CH3, J = 6.8 Hz), 2.04 s
(3H, CH3), 2.06 s (3H, CH3), 2.18 s (3H, CH3), 2.27 s
(3H, CH3), 2.38 d.d (1H, 7-H, J = 12.8, 9.6 Hz),
2.96 d.d (1H, 7-H, J = 12.8, 4.2 Hz), 3.77 m (1H,
OCH2) 3.81 s (3H, OCH3), 3.94 m (1H, OCH2),
5.64 d.d (1H, CH, J = 9.6, 4.2 Hz), 6.95–7.29 m
(10H, Harom). Found, %: C 73.39; H 6.18; N 2.63.
C33H33NO6. Calculated, %: C 73.45; H 6.16; N 2.70.
6-Butoxy-7a-(4-methylbenzoyl)-1,4-bis(4-methyl-
phenyl)-1,2,3,6,7,7a-hexahydropyrano[4,3-b]pyr-
role-2,3-dione (IIIb) was synthesized in a similar way.
Yield 78%, mp 150–151°C. IR spectrum, ν, cm–1:
1
1720, 1684. H NMR spectrum, δ, ppm: 0.92 t (3H,
CH3, J = 7.2 Hz), 1.39 m (2H, CH2), 1.60 m (2H,
CH2), 2.31 s (3H, CH3), 2.37 s (3H, CH3), 2.41 s (3H,
CH3), 3.04 d.d (1H, 7-H, J = 12.4, 4.8 Hz), 3.35 d.d
(1H, 7-H, J = 12.4, 8.8 Hz), 3.78 m (1H, OCH2),
4.03 m (1H, OCH2), 5.80 d.d (1H, 6-H, J = 8.8,
4.8 Hz), 6.97–7.72 m (12H, Harom). Found, %: C 75.74;
H 6.31; N 2.61. C33H33NO5. Calculated, %: C 75.69;
H 6.35; N 2.67.
Ar2
O
OAlk
H2C
Ar2CO
O
IIa, IIb
O
O
Ar2CO
O
N
AlkO
N
Ar2CO
IIIa, IIIb
Ar1
Ar1
Ia, Ib
I, III, Ar1 = 4-MeOC6H4, Ar2 = 2,5-Me2C6H3 (a), Ar1 = Ar2 =
4-MeC6H4 (b); II, III, Alk = Et (a), Bu (b).
The IR spectra were recorded on an FSM-1201
spectrometer from samples dispersed in mineral oil.
1
The H NMR spectra were obtained on a Bruker AM-
6-Ethoxy-7a-(2,5-dimethylbenzoyl)-4-(2,5-di-
methylphenyl)-1-methoxyphenyl-1,2,3,6,7,7a-hexa-
hydropyrano[4,3-b]pyrrole-2,3-dione (IIIa). A solu-
tion of 1.5 mmol of ethyl vinyl ether in 5 ml of anhy-
drous benzene was added to a solution of 1.0 mmol of
compound Ia in 50 ml of anhydrous benzene. The mix-
ture was heated for 25 min at 60–70°C and cooled, the
solvent was removed, and the residue was recrystal-
lized from benzene–hexane (1:1). Yield 86%, mp 151–
400 instrument at 400 MHz using DMSO-d6 as solvent
and tetramethylsilane as internal reference. The purity
of the isolated compounds was checked by TLC on
Silufol plates using benzene–ethyl acetate (5:1) and
ethyl acetate as eluent.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 08-03-01032).
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