Continuous-flow organocatalyzed Diels–Alder reactions have been performed with excellent enantioselectivity for the first time in a chiral “homemade” HPLC column, packed with silica on which a MacMillan catalyst has been supported by a straightforward immobilization procedure. The versatility of the system was also proven by running with the same column continuous-flow stereoselective reactions with
Poly(methylhydrosiloxane)-supported chiral imidazolinones: new versatile, highly efficient and recyclable organocatalysts for stereoselective Diels–Alder cycloaddition reactions
作者:Stefania Guizzetti、Maurizio Benaglia、Jay S. Siegel
DOI:10.1039/c2cc17919a
日期:——
supported organic catalysts promoted the Diels-Alder reaction of dienes with alpha,beta-unsaturated aldehydes, also in pure water, in yields and enantiomeric excesses comparable to those observed with the non-supported catalysts (up to 93% ee). Recycling of the catalysts was performed with no loss of enantioselectivity for at least five reaction cycles.
Solid Supported Chiral <i>N</i>
-Picolylimidazolidinones: Recyclable Catalysts for the Enantioselective, Metal- and Hydrogen-Free Reduction of Imines in Batch and in Flow Mode
organocatalysts for the catalytic reduction of imines with trichlorosilane has been developed. Polystyrene proved to be a more effective support than silica in terms of both chemical and stereochemical efficiency. Even with a loading as low as 1 mol% the best performing supported catalyst showed a remarkable activity and stereocontrol ability, promoting the reduction with stereoselectivities reaching 98% ee and