Functionalization of Fe3O4 magnetic nanoparticles for organocatalytic Michael reactions
作者:Paola Riente、Carolina Mendoza、Miquel A. Pericás
DOI:10.1039/c1jm10535c
日期:——
(S)-α,α-Diphenylprolinol trimethylsilyl ether supported onto well-defined (5.7 ± 1.1 nm) superparamagnetic Fe3O4 nanoparticles was used as a highly active, magnetically recoverable and reusable catalyst for the asymmetric, organocatalytic Michael addition of propanal to nitroolefins leading to high enantioselectivities. The assembly of the catalytic functional nanoparticles involves two successive steps: (i) introduction of a 3-azidopropyl unit through the formation of Si–O bonds, and (ii) integration of the organocatalytic unit by means of a copper-catalysed alkyne–azide cycloaddition reaction leading to a 1,2,3-triazole linker. Neither the process of nanoparticle assembly nor its catalytic use in dichloromethane solution provokes particle growth or agglomeration, this behaviour being key for the observation of high catalytic activity and for recyclability.
Polystyrene-Supported Diarylprolinol Ethers as Highly Efficient Organocatalysts for Michael-Type Reactions
作者:Esther Alza、Sonia Sayalero、Pinar Kasaplar、Diana Almaşi、Miquel A. Pericàs
DOI:10.1002/chem.201101730
日期:2011.10.4
addition of aldehydes to nitroolefins and of malonates or nitromethane to α,β‐unsaturated aldehydes. The combination of the catalytic unit, the triazole linker, and the polymeric matrix provides unprecedented substrate selectivity, in favor of linear, short‐chain aldehydes, when the organocatalyzed reaction proceeds by an enamine mechanism. High versatility is noted in reactions that proceed via an iminium
A Highly Selective, Polymer-Supported Organocatalyst for Michael Additions with Enzyme-Like Behavior
作者:Esther Alza、Miquelâ A. Pericà s
DOI:10.1002/adsc.200900817
日期:2009.12
A polymer-supported α,α-diarylprolinol silyl ether displays catalytic activity and enantioselectivity comparable to the best homogeneous catalysts in the Michaeladdition of aldehydes to nitroolefins. Above all, the combination of polymer backbone, triazole linker, and catalytic unit confers to it an unprecedented substrate selectivity in favor of linear, short-chain aldehydes.
Superparamagnetic Nanoparticle-Supported (S)-Diphenyl- prolinol Trimethylsilyl Ether as a Recyclable Catalyst for Asymmetric Michael Addition in Water
作者:Bang Gen Wang、Bao Chun Ma、Qiong Wang、Wei Wang
DOI:10.1002/adsc.201000508
日期:2010.11.22
A new superparamagneticnanoparticle-supported (S)-diphenylprolinol trimethylsilylether (Jørgensen–Hayashi catalyst) was synthesized and applied for the asymmetricMichaeladdition of aldehydes to nitroalkenes in water, which gives products in moderate to good yields (up to 96%), good enantioselectivity (up to 90% ee) and diastereoselectivities (up to 99:1). The immobilized catalyst could be easily
“Bottom-Up” Embedding of the Jørgensen-Hayashi Catalyst into a Chiral Porous Polymer for Highly Efficient Heterogeneous Asymmetric Organocatalysis
作者:Chang An Wang、Zhi Kun Zhang、Tao Yue、Ya Lei Sun、Lei Wang、Wei David Wang、Yuan Zhang、Chong Liu、Wei Wang
DOI:10.1002/chem.201200753
日期:2012.5.29
construction of a robust chiralporouspolymer (JH‐CPP) embedded with the Jørgensen–Hayashicatalyst (JH) has been successfully achieved for highlyefficientheterogeneousorganocatalysis. The high BET surface area, wide openings and interconnected nanopores of JH‐CPP increase the accessibility of catalytic sites and as such the catalyst shows excellent activity in catalyzing the asymmetric Michael addition