Highly ordered acid functionalized SBA-15: a novel organocatalyst for the preparation of xanthenes

Abstract

Post-synthesis modification of SBA-15 has been carried out to design highly ordered acid functionalized hybrid mesoporous organosilica, AFS-1. This material has been used as an efficient heterogeneous organocatalyst for the syntheses of xanthenes under mild conditions in the absence of any other metal co-catalyst.

Urea–pyridine bridged periodic mesoporous organosilica: An efficient hydrogen-bond donating heterogeneous organocatalyst for Henry reaction

“…The development of new heterogeneous organocatalysts other than metal-based heterogeneous catalysts has attracted a lot of attention owing to their several advantages including the robustness, low toxicity without metal-leaching problem during the reactions, inertness to moisture and oxygen, and simple handling and storage capability in the vicinity of green chemistry [10,11]. Recently, a few successful studies have been reported regarding the incorporation of urea based HBD molecules onto the solid architectures to overcome abovementioned problems.…”

Functionalized mesoporous materials as efficient organocatalysts for the syntheses of xanthenes

“…In one approach surface carboxylic acid ( CO 2 H) functionalized mesoporous silica has been prepared via Schiff-base condensation of 3-aminopropyl grafted SBA-15 [36]. In the other case sulfonic acid ( SO 3 H) functionalized mesoporous silica has been prepared from 3-mercaptopropyl grafted MCM-41 via partial oxidation with hydrogen peroxide (H 2 O 2 ).…”

“…Both the acid functionalized materials can be used as catalyst for the condensation reaction of aromatic aldehyde and 2-naphthol to prepare different value added xanthene derivatives. The CO 2 H functionalized mesoporous silica can be used as a catalyst under ambient conditions in the presence of dichloromethane (DCM) as the solvent, whereas for the SO 3 H functionalized material catalysis proceeds under solvent-free conditions at 363 K. Synthesis of CO 2 H functionalized mesoporous silica, AFS-1 has been carried out as described in our previous communication (Scheme 1) [36].…”

Phosphosulfonic acid, an efficient solid acid catalyst for the one-pot preparation of 14-aryl-14H-dibenzo[a,j]xanthenes and 1,8-dioxo-octahydro-xanthenes under solvent-free conditions

“…A literature search revealed that many procedures have been developed for the preparation of the biologically important xanthene derivatives, 14-aryl-14H--dibenzo[a,j]xanthenes, through the dehydration of β-naphthol and aromatic aldehydes in the presence of various catalysts, such as AcOH-H 2 SO 4 , 7 selectfluor (1-(chloromethyl-4-fluoro-1,4-diazoniabicyclo [2.2.2]octane bis(tetrafluoroborate)), 8 wet cyanuric chloride, 9 Sc[N(SO 2 C 8 F 17 ) 2 ] 3 in a fluorine-containing solvent, 10 17 and sulfonic acid-functionalized silica (SiO 2 -Pr-SO 3 H). 18 In the same manner, the synthesis of 1,8-dioxooctahydroxanthenes was achieved through the dehydration of dimedone (5,5-dimethylcyclohexane-1,3--dione) and aromatic aldehydes in pseudo three-component reactions in the presence of a catalyst, such as, tetrabutylammonium hydrogen sulfate, 19 Sc 3+ -montmorillonite, 20 HClO 4 -SiO 2 and polyphosphoric acid (PPA)-SiO 2 , 21 phosphomolybdic acid (PMA)-SiO 2 , 22 acidic ionic liquids, 23 heteropoly tungstic acid (HPWA) loaded Si-mobile crystalline material (HPWA-MCM-41) mesoporous molecular sieves, 24 silica-supported Preyssler nanoparticles (SPNP), 25 MCM--41-RSO 3 H, 26 acid functionalized SBA-15 and MCM-41, 27 and silica-bonded N-propylsulfamic acid (SBNPSA).…”