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-1Hpyrrole-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. Compounds IIIa and IIIb are likely to be formed via thermal [4 + 2]-cycloaddition of the conjugated O=C– C=C 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: 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-methylphenyl)-1,2,3,6,7,7a-hexahydropyrano[4,3-b]pyrrole-2,3-dione (IIIb) was synthesized in a similar way. Yield 78%, mp 150–151°C. IR spectrum, ν, cm: 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.