In the title compound, C19H16BrClO4, both the fused xanthene rings and one of the cyclo-hexane rings adopt envelope conformations, while the other cyclo-hexane ring is in a chair conformation. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming infinite chains running along [10-1] incorporating R 2 (2)(16) ring motifs. In addition, C-H⋯π inter-actions and weak π-π stacking in...

In the title mol-ecule, C(36)H(25)NO(3), the β-lactam ring is essentially planar, with a dihedral angle of 3.3 (2)° between the two separate three-atom N/C/C planes. The β-lactam ring makes dihedral angles of 28.45 (14), 87.4 (1) and 51.8 (1)° with the mean planes of the benzene, xanthene and anthracene ring systems, respectively. In addition to a weak intra-molecular C-H⋯N hydrogen bond, the c...

nano-silica supported titanium tetrachloride (ticl4.sio2) was prepared and used as an acid catalyst for the 14-aryl or alkyl-14h-dibenzo[a,,j]xanthenesreaction under solvent-free conditions. compared to the classical 14-aryl or alkyl-14h-dibenzo[a,j]xanthenesreaction conditions, this method consistently has the advantage of excellent yields, mild reaction conditions, ease of workup, survival of...

The recent development of the dye laser [1] 1 has opened up an important new field of applications for organic dyes. This has led to a renewed interest in the theory of nonradiative transitions in dyes and also to the synthesis of new highly fluores cent dyes. In this article we review briefly the relations between fluor· escence and molecular structure in the most important classes of laser dy...

The indium(III)-catalyzed cascade cycloisomerization reaction of 1,5-enynes with pendant aryl nucleophiles is reported. proceeds in under mild conditions, using InI3 (5 mol %) as a catalyst range furnished groups (phenyl and phenol) at alkene (E Z isomers) terminal internal alkynes. Using 1-bromo-1,5-enynes, one-pot sequential indium-catalyzed palladium-catalyzed cross-coupling triorganoindium ...

The reaction of 5,5-dimethylcyclohexane-1,3-dione with various heteroarylaldehydes afforded the corresponding heteroaryl substituted xanthene derivatives 1(a-f). The reaction proceeds via the initial Knoevenagel, subsequent Michael, and final heterocyclization reactions using 1,4-diazabicyclo[2.2.2]octane (DABCO) as a catalyst in aqueous media. The synthesized heteroaryl substituted xanthenes 1...

We present a design strategy for fluorescence probes with a high off/on activation ratio in the red wavelength region, based on a novel fluorescein analogue in which the O atom at the 10 position of the xanthene chromophore is replaced with a Si atom. To demonstrate the usefulness of this strategy, we designed and synthesized a red-fluorescent probe for β-galactosidase, and showed that it works...

In the title compound, C(21)H(21)NO(6), each of the cyclo-hexenone rings adopts a half-chair conformation. Each of the pairs of hy-droxy and carbonyl O atoms are oriented to allow for the formation of intra-molecular O-H⋯O hydrogen bonds, which are typical of xanthene derivatives.

A new fluorescent sensor based on a dimethylxanthene skeleton has beensynthesized. Because of its oxyanion hole structure, this receptor includes a suitablecavity for the association of carboxylic acids. The receptor's fluorescence is quenchedupon addition of dinitrobenzoic acid.