Data. 7-Aryl-7H-bis  benzopyrano [4,3-b: 3', 4'-c] pyran-6, 8-dione (4d): 0.5 g m.p 323 °C. IR (KBr): 1350, 1430, 1600, 1640–1650, 1700, 2820 cm-1. 1H NMR (CDCl3, 400 MHz): δ 7.5–7.9 (12H,m,ArH),4.98 (1H,s,-CH-). m/z 419 (M+), 392, 317, 265, 196, 121, 94 and 60. Same results were obtained when the reaction was carried out at water bath temperatures. A mixture of DMSO (10 ml), acetic anhydride (5 ml) and (1e) (1.5 g) was kept at room temperature for 9 days. A yellow crystalline product
which separated out was Selleck Anti-cancer Compound Library filtered, washed and crystallized from benzene and identified as 7-Aryl-7H-bis  benzopyrano [4,3-b: 3′, 4′-c] pyran-6, 8-dione (4e). The mother liquor upon addition of water and extraction with
ethyl INCB018424 nmr acetate afforded a solid which was crystallized from benzene and identified as (9). Data. 7-Aryl-7H-bis  benzopyrano [4,3-b: 3', 4'-c] pyran-6, 8-dione(4e): (0.5 g) IR (KBr): 1250, 1360, 1600, 1655 and 1720 cm−1. 1H NMR (DMSO-d6, CFT-20): δ 7.45–8. (12H,m,ArH),6.2 (1H,s,-CH-). m/z 422(M+), 409, 393, 317, 265, 176, 121 and 120. (Found C, 68.48; H, 2.58. C25H13NO7 required C,68.33; H, 2.96%). Product (9): m.p 271 °C; (1.6 g). IR (KBr): 1410, 1640, 1700, 1760, 2850 and 3350 cm−11H NMR (CDCl3 EM 390 90 MHz): δ 7–8.25(12H,m,ArH),4.75 (1H,s,-CH-), 3.77(2H,s,-CH2-), 2.84(1H,s,-OH-). m/z 487, 440, 365, 249, 175 and 121. (Found C, 64.18; H, 3.27. C26H17NO9 requires C,64.06; H,3.49%). At room temperature DMSO-acetic anhydride converts (1a) obtained easily by the reaction of 4-hydroxycoumarin with benzaldehyde,5 to a novel product (3) in excellent yields. On the basis of its mass spectrum and elemental analysis the molecular formula of the compound comes out to be C25H14O6 .Two structures (2a) and (3) were possible for the compound but the former is ruled out on the basis of proton magnetic resonance (pmr). The out 1H singlet at δ 4.73 can be assigned to the benzylic and allylic proton. The carbonyl bands at 1790, 1720 and 1680 cm−1
in the infrared spectrum are also at right values for saturated lactone, coumarin and benzoyl carbonyl groups respectively. The treatment of (la) with DMSO-acetic anhydride at 160 °C, proved destructive. At water bath temperature, however, a yellow crystalline solid (4a) gradually separated from the reaction mixture and was filtered off at the end of reaction. Its pmr spectrum shows in addition to thirteen aromatic protons, a singlet at δ 5.17 belonging to doubly allylic and benzylic methine proton suggesting structure (4a) for the compound which was further confirmed by infrared spectrum showing a broad signal at 1720 cm−1 and 1655 cm−1 for two, α–β-unsaturated lactone carbonyls and for enol ethers respectively.