Dongdong Wu

Photoinduced reactions of bicycloalkylidenes with isatin and isoquinolinetrione

Photoinduced reactions of isatin and N-methyl-1,3,4-isoquinolinetrione with bicycloalkylidenes such as bicyclopropylidene, cyclopropylidenecyclobutane, cyclopropylidenecyclohexane and bicyclohexylidene were investigated. The reactions gave spirooxetanes as the major products derived from the [2 + 2] photocycloaddition pathway via 1,4-biradical recombination. Unusual products including the [4 + 2 + 2] cycloadducts, the oxoisochroman derivatives and other ring-rearranged products were derived from competitive pathways via 1,6-biradical recombination. The presence of oxygen in the reaction solution was found to be relevant to the distribution of different types of products. Mechanisms were proposed to rationalize the chemo- and regioselectivity in the photoreactions and the origin of the different types of products.

Acid-mediated transformation of spirocyclopropyl oxetanes: a facile approach to spirocyclopropyl butenolides and γ-butyrolactones

Spirocyclic oxetanes were found to undergo versatile transformations under different acid-mediated conditions. Treatment of spirocyclopropyl oxetanes with excess amounts of hydrochloric or hydrobromic acid at room temperature resulted in the formation of spirocyclopropyl fused butenolides with good yields. The transformation of spirocyclopropyl oxetanes mediated by hydroiodic acid led to spirocyclopropyl fused γ-butyrolactones instead of butenolides. Transformation of spirocyclopropyl oxetanes catalyzed by Lewis acid was also explored and found to give distinct products such as spirobutyl indolinones. The reaction mechanisms involved in the acid-mediated transformations were proposed.

6-Meth-oxy-4-methyl-2H-chromen-2-one.

The whole molecule of the title coumarin derivative, C11H10O3, is approximately planar, with a maximum deviation of 0.116 (3) Å from the least-squares plane defined by all non-H atoms. In the crystal, adjacent molecules are linked into chains along [011] via intermolecular C—H⋯O hydrogen bonds.

N-(2-Oxo-2-phenyl­acet­yl)benzamide

In the title compound, C15H11NO3, the two essentially planar benzaldehyde groups [maximum deviations = 0.0487 (12) and 0.0205 (10) Å] are inclined at a dihedral angle of 72.64 (6)° with respect to each other. The bridging C—C—N—C torsion angle is 22.58 (18)°. In the crystal, intermolecular bifurcated acceptor N—H⋯O and C—H⋯O hydrogen bonds link inversion-related molecules into dimers incorporating R 1 2(7) and R 2 2(8) ring motifs. The crystal structure is further stabilized by weak intermolecular C—H⋯π interactions.

1,1′-Bicyclo­hexyl-1,1′-diyl 1,1′-biphenyl-2,2′-dicarboxyl­ate

The title compound, C26H28O4, lies about a crystallographic twofold rotation axis. The cyclohexane rings adopt a chair conformation. The two benzene rings form a dihedral angle of 40.82 (3)°. No significant intra- or intermolecular interactions are observed in the crystal structure.

1,1'-Bicyclo-hexyl-1,1'-diyl 2,2'-bipyridine-3,3'-dicarboxyl-ate.

The title compound, C24H26N2O4, lies about a crystallographic twofold rotation axis. The cyclohexane rings adopts a chair conformation. The two pyridine rings form a dihedral angle of 41.02 (4)°. In the crystal, molecules are linked via C—H⋯O and C—H⋯N hydrogen bonds into a layer parallel to the bc plane.

1-(4-Meth­oxy­phen­yl)ethane-1,2-diyl 1,1′-biphenyl-2,2′-dicarboxyl­ate

In the title molecule, C23H18O5, the methoxy-substituted benzene ring makes dihedral angles of 65.12 (4) and 88.55 (4)° with the other two benzene rings. These two benzene rings form a dihedral angle of 45.70 (4)°. In the crystal, molecules are linked into inversion dimers by pairs of weak C—H⋯O hydrogen bonds.

1-Phenylethane-1,2-diyl 1,1′-biphenyl-2,2′-dicarboxylate

In the title compound, C22H16O4, the 7-phenyl ring is inclined at dihedral angles of 36.73 (9) and 69.37 (9)° with respect to the biphenyl benzene rings. The two benzene rings of the biphenyl unit form a dihedral angle of 55.99 (8)°. There are no significant hydrogen bonds observed in the crystal of this compound.

1-(2-Bromophenyl)ethane-1,2-diyl 1,1′-biphenyl-2,2′-dicarboxylate

In the title compound, C22H15BrO4, the bromobenzene ring is inclined at dihedral angles of 23.87 (11) and 52.37 (11)° with respect to the planes of the two benzene rings. The two benzene rings of the biphenyl unit form a dihedral angle of 49.08 (11)°. In the crystal, molecules are linked into [100] chains by C—H⋯O hydrogen bonds.

2-Phenyl-2,3-dihydro-phenanthro[9,10-b][1,4]dioxine.

In the title compound, C22H16O2, the phenanthrene ring system is essentially planar [maximum deviation = 0.058 (1) Å] and is inclined at an angle of 58.39 (6)° to the phenyl ring. The 1,4-dioxane ring is in a chair conformation. In the crystal, molecules are stacked along the b axis, but no significant hydrogen bonds are observed.