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.
The asymmetric challenge! New camphor‐based prolinamides were designed, synthesized, and proven to be a highly efficient organocatalysts for asymmetricMichael reactions. Treatment of unmodified aldehydes with nitroalkenes in the presence of 5–10 mol % organocatalysts provided the desired Michael products in high chemical yields (up to 94 %) and high to excellent levels of diastereo‐ and enantioselectivities
Translating the Enantioselective Michael Reaction to a Continuous Flow Paradigm with an Immobilized, Fluorinated Organocatalyst
作者:Irina Sagamanova、Carles Rodríguez-Escrich、István Gábor Molnár、Sonia Sayalero、Ryan Gilmour、Miquel A. Pericàs
DOI:10.1021/acscatal.5b01746
日期:2015.11.6
enantioselective, continuous flow processes allowing either the multigram synthesis of a single Michael adduct over a 13 h period or the sequential generation of a library of enantiopure Michael adducts from different combinations of substrates (13 examples, 16 runs, 18.5 h total operation). A customized in-line aqueous workup, followed by liquid–liquid separation in flow, allows for product isolation