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A Mesoporous Organosilica-Supported Organocatalyst
J. Y. Shi, C. A. Wang, Z. J. Li, Q. Wang, Y. Zhang, W. Wang*
Lanzhou University, P. R. of China
20 July 2011 (online)
A chiral imidazolidinone catalyst (MacMillan catalyst) was supported on hollow-structured phenylene-bridged periodic mesoporous organosilica (H-PhPMO) spheres. Thus, the supported catalyst (H-PhPMO-Mac) was prepared from 1,4-bis(triethoxysilyl)benzene and trimethoxysilylpropyl azide with hematite (α-Fe2O3) nanoparticles as hard templates through condensation, etching (removal of α-Fe2O3), and Huisgen 1,3-dipolar cycloaddition. The Diels-Alder cycloaddition of trans-cinnamaldehyde (0.25 mmol) and 1,3-cyclopentadiene (1.25 mmol) was carried out with H-PhPMO-Mac (0.05 mmol) to give 3-phenylbicyclo-[2,2,1]hept-5-ene-2-carbaldehyde in 98% yield [endo/exo = 1:1.1; 81% ee (endo) and 81% ee (exo)].