Supported and Unsupported Chiral Squaramides as Organocatalysts for Stereoselective Michael Additions: Synthesis of Enantiopure Chromenes and Spirochromanes
作者:José M. Andrés、Jorge Losada、Alicia Maestro、Patricia Rodríguez-Ferrer、Rafael Pedrosa
DOI:10.1021/acs.joc.7b01177
日期:2017.8.18
Novel supported chiral bifunctional squaramides have been easily prepared starting from diamines derivedfrom natural amino acids and commercially available aminoalkyl polystyrene resins. These squaramides behave as excellent stereoselective recoverable organocatalysts in different Michael additions, in neat conditions at room temperature. The reaction on 2-(2-nitrovinyl) phenol as electrophile lead
The first squaramide-decorated covalent organic framework has been successfully constructed, which exhibited excellent performance in biomimetic hydrogen-bonding organocatalysis.
第一个以方酰胺修饰的共价有机框架已成功构建,表现出在生物模拟氢键有机催化中的优异性能。
A Polystyrene-Supported, Highly Recyclable Squaramide Organocatalyst for the Enantioselective Michael Addition of 1,3-Dicarbonyl Compounds to β-Nitrostyrenes
作者:Pinar Kasaplar、Paola Riente、Caroline Hartmann、Miquel A. Pericàs
DOI:10.1002/adsc.201200526
日期:2012.11.12
A chiral squaramide has been supported onto a polystyrene (PS) resin through a copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction and used as a very active, easily recoverable and highly reusable organocatalyst for the asymmetric Michaeladdition of 1,3-dicarbonylcompounds to β-nitrostyrenes. The PS-supported squaramide could be recycled up to 10 times.
motifs in organocatalysis, whereas efficient 1,3‐diamine‐derived organocatalysts are very rare. Herein we report a highly efficient camphor‐1,3‐diamine‐derived squaramideorganocatalyst. Its catalytic activity in Michaeladditions of 1,3‐dicarbonyl nucleophiles to trans‐β‐nitrostyrene derivatives provides excellent enantioselectivities (up to >99% ee).
Tether-Free Immobilized Bifunctional Squaramide Organocatalysts for Batch and Flow Reactions
作者:György Kardos、Tibor Soós
DOI:10.1002/ejoc.201300626
日期:2013.7
accessible, and robust immobilizedbifunctionalorganocatalysts. There was no need to employ any tether to secure high enantio- and diastereoselectivities in various Michael addition reactions. The synthetically useful Michael adducts were obtained within reasonable reaction times with the advantage of easy product isolation and the possibility of automation by using a flow chemistry apparatus.