Pyrimidine-Derived Prolinamides as Recoverable Bifunctional Organocatalysts for Enantioselective Inter- and Intramolecular Aldol Reactions under Solvent-Free Conditions
作者:Pascuala Vizcaíno-Milla、José M. Sansano、Carmen Nájera、Béla Fiser、Enrique Gómez-Bengoa
DOI:10.1002/ejoc.201500007
日期:2015.4
ChiralL-prolinamides 2 containing the (R,R)- and (S,S)-trans-cyclohexane-1,2-diamine scaffold and a 2-pyrimidinyl unit are synthesized and used as general organocatalysts for intermolecular and intramolecular aldolreactions with 1,6-hexanedioic acid as a co-catalyst under solvent-free conditions. The intermolecular reaction between ketone–aldehyde and aldehyde–aldehyde must be performed under wet
Cross-Linked-Polymer-Supported<i>N</i>-{2′-[(Arylsulfonyl)amino][1,1′-binaphthalen]-2-yl}prolinamide as Organocatalyst for the Direct Aldol Intermolecular Reaction under Solvent-Free Conditions
procedure with polymer 5b was extended to the aldolreaction under solvent‐free conditions of other ketones, including functionalized ones, and different aromatic aldehydes (Table 3). In some cases, the addition of a small amount of H2O was required to give the best results (up to 95% ee). Under these reaction conditions, the cross‐aldolreaction between aldehydes proceeded in moderate yield and diastereo‐
catalytic system for the enantioselective direct aldolreaction between different ketones and aldehydes under solvent-free or aqueous conditions. The polystyrene-supported N-sulfonyl-(Ra)-binam-D-prolinamide catalyst in combination with benzoic acid showed similar results to those obtained with unsupported N-tosyl-binam-derived prolinamide under similar reaction conditions. The aldol products were obtained
A Highly Efficient Solvent-Free Asymmetric Direct Aldol Reaction Organocatalyzed by Recoverable (<i>S</i>)-Binam-<scp>l</scp>-Prolinamides. ESI-MS Evidence of the Enamine−Iminium Formation
作者:Gabriela Guillena、Maria del Carmen Hita、Carmen Nájera、Santiago F. Viózquez
DOI:10.1021/jo800773q
日期:2008.8.1
equiv but also the reaction time to give the aldol products with regio-, diastereo-, and enantioselectivities comparable to those in organic or aqueous solvents. Generally anti-isomers are mainly obtained with enantioselectivities up to 97%. The reaction can be carried out under these conditions also using aldehydes as nucleophiles, yielding after in situ reduction of the aldol products the corresponding
Bio-renewable enantioselective aldol reaction in natural deep eutectic solvents
作者:Regina Martínez、Lucía Berbegal、Gabriela Guillena、Diego J. Ramón
DOI:10.1039/c5gc02526e
日期:——
A recoverable glucose based eutectic solvent/l-proline system has been used as a reaction medium to perform the enantioselective organocatalysed aldol reaction.