water-compatible proline catalysts (4–6) derived from calixarene bearing a hydrophobic nature have been synthesised. It was found that the compound 4 was a highly efficient organocatalyst for aldol reactions occurred in the water. Under optimised reaction conditions, high yields (up to 82%), good enantioselectivities (ee up to 81%) and high diastereoselectivities (dr up to 91:9) were obtained.
successfully used as a cocatalyst for L-proline catalyzed aldolreactions in the presence of water. The anticonfigured products were obtained with good yields (up to 94%), high diastereoselectivities (up to 95:5), and high enantiomeric excesses (up to 93% ee ). The successful results for catalytic efficiency of L-proline in the presence of water reveal the importance of the hydrophobic nature of cholesterol
Design and preparation of a novel prolinamide-based organocatalyst for the solvent-free asymmetric aldol reaction
作者:Rafaela de S. Martins、Mathias P. Pereira、Pedro P. de Castro、Fernanda I. Bombonato
DOI:10.1016/j.tet.2019.130855
日期:2020.1
proline-derived catalyst, providing access to the desired adducts in up to 95% yield, 1:19 syn/anti and 98% e.e. Moreover, even sterically bulky aldehydes and substituted cyclohexanones were well tolerated. DFT calculations and control experiments indicated that several hydrogen bonding interactions between the aldehyde and the enamine intermediate are responsible for the stereoselective chiral induction process
Synthesis of a new chiral organocatalyst derived from (S)-proline containing a 1,2,4-triazolyl moiety and its application in the asymmetric aldol reaction. Importance of one molecule of water generated in situ
作者:Omar Sánchez-Antonio、Eusebio Juaristi
DOI:10.1016/j.tetlet.2019.151128
日期:2019.10
yield. Our triazolyl-containing heterocycle was evaluated as organocatalyst (10 mol% load, under neat reaction conditions) in the enantioselective aldolreaction between four different types of ketones and a variety of aryl aldehydes. Good results in terms of enantioselectivity and chemical yield were observed under solvent-free reaction conditions and in the absence of any additive. Evidence is provided
Synthesis of Chiral Organocatalysts derived from Aziridines: Application in Asymmetric Aldol Reaction
作者:Shikha Gandhi、Vinod K. Singh
DOI:10.1021/jo8019863
日期:2008.12.5
We report the synthesis of a new series of highly efficient chiral organocatalysts derived via the regio- and stereoselective ring opening of chiral aziridines with azide anions. The catalysts have proved to be very efficient for a direct asymmetric aldolreaction, both with cyclic as well as acyclic ketones in brine with 2 mol % of catalyst loading, and afforded the products in excellent yields (up