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...

In the title compound, C(25)H(29)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. The nitro group is rotationally disordered over two orientations in a 0.544 (6):0.456 (6) ratio. In the crystal, we...

In the title compound, C(26)H(25)FO(5), the terminal cyclo-hexane rings of the xanthene ring system adopt half-boat conformations. The 4H-chromene ring make a dihedral angle of 87.94 (5)° with the xanthene ring system and its carbonyl O atom lies above the xanthene O atom. In the crystal, mol-ecules are linked into ribbons propagating along the a-axis direction by C-H⋯O hydrogen bonds. Aromatic...

In the xanthene ring system in the title compound, C19H18O4, the 4H-pyran ring has a maximum deviation of 0.110 (2) Å from planarity and the cyclo-hexene ring exhibits a puckered conformation [puckering parameters Q T = 0.452 (3) Å, θ = 57.0 (4) and ϕ = 131.7 (4)°]. The cyclo-hexene ring attached to the xanthene system adopts an envelope conformation, with the middle of the three methylene C at...

The title compound, C(35)H(35)ClN(4)O(3), resulted from a spiro-lactam ring closure of rhodamine B dye. The xanthene ring system is approximately planar [r.m.s. deviation = 0.050 (9) Å for the xanthene ring]. The dihedral angles formed by the spiro-lactam and 5-chloro-2-hy-droxy-benzene rings with the xanthene ring system are 87.9 (7) and 79.1 (7)°, respectively.

Cellulose bonded N-propyl diethylene tetra sulfamic acid (CBPDETSA) was successfully applied as a green and recyclable acidic catalyst for the synthesis of tetrahydrobenzo [a] xanthene-11-one as an important class of potentially bioactive compounds. The products are obtained by the coupling of 2-naphtol , cyclohexadione and aldehyde derivatives in good to high yields (70- 92%) under solvent-fre...

A simple and ecofriendly method was developed for the synthesis of arylmethylene[bis(5,5- dimethyl-3-hydroxy-2-cyclohexene-1-ones)] from the reaction of 5,5-dimethylcyclohexane- 1,3-dione and aromatic aldehydes in an aqueous media without any catalyst via Knoevenagel condensation followed by rapid Michael addition. No cyclization product was down to convert these enolic forms to xanthene deriva...