(-)-(3a'S,4'S,9b'S,1R,2S,5R)-4'-Ethyl-3a',4',5',7',8',9b'-hexahydro-2-isopropyl-5-methyl-2'-phenyl­spiro­[cyclo­hexane-1,7'-dioxino[3,2-e]isoindole]-1',3',9'-trione

The title compound, C₂₇H₃₃NO₅, obtained from diethyl ether, crystallizes in space group P2₁ with four molecules in the asymmetric unit. The dioxinone and imide rings are almost planar, whereas the cyclo­hexane and cyclohexene rings form distorted conformations. The crystal structure confirms an earlier proposal about the stereoselectivity of Diels-Alder reactions to spiro­cyclic chiral 1,3-dienes.

Methyl [4-methoxy-3-(methyl­sulfonyl­oxy)­benzoyl]­formate

The crystal structure of the title compound, C₁₁H₁₂O₇S, confirms an earlier proposal concerning the regioselectivity of electrophilic substitution reactions of mesyl guaiacol.

4-(3-Hydroxy-4-methoxy­phenyl)-3-(3,4,5-tri­methoxy­phenyl)-2,5-di­hydro-1H-pyrrole-2,5-dione

The title compound, C₂₀H₁₉NO₇, crystallizes in the space group Pna2₁. X-ray analysis shows the compound has the desired 3'-hydroxy and 4'-methoxy substitution pattern, as in the natural template combretastatin A-4.

3-(1H-Indol-3-yl)-4-(3,4,5-tri­methoxy­phenyl)-2,5-di­hydro-1H-pyrrole-2,5-dione

The crystal structure of the title compound, C₂₁H₁₈N₂O₅, was determined in order to study the electrocyclic reactivity of 3,4-di­aryl-1H-pyrrole-2,5-dione derivatives. Intermolecular hydrogen bonds form sheets.

5,6,7-Tri­methoxy-2,3-di­hydro-1H,8H-benzo­[a]­pyrrolo­[3,4-c]­carbazole-1,3-dione di­methyl sulfoxide solvate

The crystal structure of the title compound, C₂₁H₁₆N₂O₅·C₂H₆OS, was determined to investigate the electrocyclic reactivity of 3,4-di­aryl-1H-pyrrole-2,5-diones (3,4-bisarylmal­eimides) to the yield corresponding carbazole derivatives.

(3RS,1SR)-3-Bromo-3-(1-phenyl­propyl)­chroman-2,4-dione

The title compound, C₁₈H₁₅BrO₃, was obtained by bromination of phenprocoumone with N-bromo­succin­imide. The X-ray structure confirms an earlier proposal concerning the regioselectivity of the reaction to introduce the Br atom at the 3-position.