Crystal structure of 5-hydroxy-2,3,8,8-tetramethyl-4H,8H-benzo[1,2-b: 5,4-b']dipyran-4-one, C16H16O4

Ci6Hi604, monoclinic, PYl\lc\ (no. 14), a = 9.149(2) A, b = 13.029(3) A, c = 11.608(2) A,jS = 99.90(3)°, V= 1363.1 A, Z = 4, Rgt(F) = 0.046, wR^F2) = 0.122, T= 296 K. Source of material Title compound was prepared from a modified literature procedure [1] via a reaction of one equivalent of 5,7-dihydroxy-2,3-dimethyl-4//-benzo[ 1,2-£]pyran-4-one with three equivalents of 4,4-dimethoxy-2-methyl-2-butanol in the presence of pyridine heated at 160 °C for ten hours under an argon atmosphere. Solvent was removed under vacuum and residue was dissolved in ethyl acetate, washed with water and dried over anhydrous sodium sulfate. The ethyl acetate layer on evaporation gave a yellow mixture which was purified over a silica gel column using dichloromethane as the eluent. Material was then crystallized from ethyl acetate/hexane to yield colorless crystals. Elemental analysis: found C, 70.04 %; H, 5.91 %; calc. for C16H16O4 C, 70.58 %; H, 5.92 %. Discussion Title compound was synthesized within a project aimed at finding agents that would exhibit significant anti-HTV activity [2]. The crystal structure indicates an angle of 22.6(2)° between the planes formed from C9-C8-C7-03 and 03-C6-C10-C9. In addition intramolecular hydrogen bonding was exhibited for 04—01, 2.569(3) A, 0 4 H 4 A 0 1 , 155(3)°. All other bonding parameters were similar to those in pyrano-isoflavone [3]. Table 1. Data collection and handling. Crystal: colorless block, size 0.20 x 0.20 x 0.40 mm Wavelength: Mo Ka radiation (0.71073 Â) 0.95 cm" Diffractometer, scan mode: Siemens P4, <0