Aryl imines formed in situ from aryl aldehydes and aromatic amines undergo smooth [4 2] cycloaddition reactions with cyclic enol ethers such as 3,4-dihydro-2H-pyran and 2,3-dihydrofuran in the presence of 10 mol % Selectfluor TM in acetonitrile at room temperature to afford pyrano-and furanotetrahydroquinoline derivatives in excellent yields with high endo-selectivity.

D-Glycals undergo smoothly allylic rearrangement with allyltrimethylsilane and trimethylsilyl cyanide in the presence of catalytic amount of bismuth triflate to afford the corresponding 2,3-unsaturated allyl glycosides and glycosyl cyanides in excellent yields with high a-selectivity.

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The molecule of the title compound C19H18O6, adopts anEconformation about the C=C double bond and the C—C=C—C torsion angle is −179.30 (16)°. The molecule is nearly planar, as indicated by the dihedral angle of 6.99 (6)° between the benzene ring and the benzodioxalane ring. In the crystal, molecules are linkedviaweak C—H...O hydrogen bonds, forming zigzag chains propagating along thebaxis.