Design, synthesis and application of chiral tetraoxacalix[2]arene[2]triazine‐based organocatalysts in asymmetric Michael addition reactions

Abstract

A novel type of oxacalix[2]arene[2]triazine-based organocatalysts for asymmetric Michael reactions are reported for the first time. Chiral subunits were attached to the heteroatom-bridged calixaromatic platform by a reaction of (R)-and (S)-1-aminotetraline with tetraoxacalix[2]arene[2]triazine in both enantiomeric forms. To evaluate the catalytic efficiency of the novel organocatalysts, isobutyraldehyde reacted with various substituted and unsubstituted aromatic trans-β-nitrostyrenes in tetrahydrofuran (THF), leading to Michael adducts in excellent yields and enantioselectivites (up to 97% yield and 99% ee).

Effective asymmetric Michael addition of anthrone to nitroalkenes using chiral tetraoxacalix[2]arene[2]triazines as organocatalysts

“…We have reported the preparation and catalytic application of upper and lower rim substituted calix[4]arenes bearing various chiral subunits and functionalities and employed as H‐bond donor chiral catalysts in a variety of stereoselective transformations over the past decade. Chiral tetraoxacalix[2]arene[2]triazine derivatives bearing secondary amine functionality have also reported very recently by us as asymmetric organocatalysts for stereoselective Michael additions of isobutyraldehyde to a variety of substituted and unsubstituted aromatic trans ‐ β ‐nitrostyrenes . In this study, we describe a highly effective one‐pot process to synthesize optically active oxacalix[2]arene[2]triazine derivatives from chiral primary amines and the application possibility of these chiral compounds as organocatalysts in the Michael reaction of anthrone with β ‐nitroolefins in mild conditions .…”

“…Chiral tetraoxacalix [2]arene [2]triazine derivatives bearing secondary amine functionality have also reported very recently by us as asymmetric organocatalysts for stereoselective Michael additions of isobutyraldehyde to a variety of substituted and unsubstituted aromatic trans-β-nitrostyrenes. 29 In this study, we describe a highly effective one-pot process to synthesize optically active oxacalix [2]arene [2]triazine derivatives from chiral primary amines and the application possibility of these chiral compounds as organocatalysts in the Michael reaction of anthrone with β-nitroolefins in mild conditions. 30,31 As far as the authors know, this is the first catalytic application report of chiral oxacalix [2]arene [2]triazine derivatives for stereoselective Michael reaction of anthrone.…”

Organocatalysis for the Asymmetric Michael Addition of Aldehydes and α,β-Unsaturated Nitroalkenes

“…As mentioned above, various reactions have been used to study organic catalysts [28][29][30]. However, to design an eco-friendly organocatalyzed reaction, many studies have focused on organic catalyst reactions that do not use solvents or use water.…”

Enantioselective Michael reaction of anthrone catalyzed by chiral tetraoxacalix[2]arene[2]triazine derivatives

“…[49][50][51] Likewise, we have recently reported substituted tetraoxacalix [2]arene [2]triazine derivatives with different purposes as chiral catalysts in the stereoselective Michael additions of isobutyraldehyde using different substituted and unsubstituted aromatic trans-b-nitrostyrenes. 52 Here, we described an efficient one-pot process to synthesize optically active tetraoxacalix [2]arene [2]triazine derivatives and their possible applications as organic catalysts in the Michael addition of anthrone to b-nitroolens under mild conditions. As far as we know, this study is the rst implementation of tetraoxacalix [2]arene [2]triazine catalysts in the enantioselective reactions of anthrone.…”