title: Heterogeneous organocatalysis at work: functionalization of hollow periodic mesoporous organosilica spheres with MacMillan catalyst.
abstract: We report a new method for the synthesis of hollow-structured phenylene-bridged periodic mesoporous organosilica (PMO) spheres with a uniform particle size of 100-200 nm using α-Fe(2)O(3) as a hard template. Based on this method, the hollow-structured phenylene PMO could be easily functionalized with MacMillan catalyst (H-PhPMO-Mac) by a co-condensation process and a "click chemistry" post-modification. The synthesized H-PhPMO-Mac catalyst has been found to exhibit high catalytic activity (98% yield, 81% enantiomeric excess (ee) for endo and 81% ee for exo) in asymmetric Diels-Alder reactions with water as solvent. The catalyst could be reused for at least seven runs without a significant loss of catalytic activity. Our results have also indicated that hollow-structured PMO spheres exhibit higher catalytic efficiency than solid (non-hollow) PMO spheres, and that catalysts prepared by the co-condensation process and "click chemistry" post-modification exhibit higher catalytic efficiency than those prepared by a grafting method.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, PR China.
authors.forename: Jiao Yi
authors.initials: JY
authors.lastname: Shi
authors.forename: Chang An
authors.initials: CA
authors.lastname: Wang
authors.forename: Zhi Jun
authors.initials: ZJ
authors.lastname: Li
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D002384:Catalysis; D057930:Click Chemistry; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013237:Stereoisomerism; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D013501:Surface-Active Agents; D014867:Water; D010165:Palladium; D012822:Silicon Dioxide