Enantioselective aza-Henry reaction of t-Boc protected imines and nitroalkanes with bifunctional squaramide organocatalysts

Abstract

A quinine-derived sterically encumbered squaramide organocatalyst afforded high enantioselectivity and excellent conversion in an aza-Henry reaction performed with imines and nitroalkanes.

Synthesis, Anti‐Oomycete and Anti‐fungal Activities of Novel Cinchona Alkaloid Derivatives Containing Sulfonate Moiety

“…Other alkaloids include quinidine (2, Figure 1), cinchonidine (3, Figure 1), and cinchonine (4, Figure 1). [23][24][25][26][27] Quinine and its analogs are not only used in antimalarial drugs, [28][29][30] synthetic catalysts, and ligands, [31][32][33] but also have various biological activities, such as insecticidal, [25][26][27] antibacterial, [34,35] and anticancer activities, [36] etc. Quinine and its analogs have attracted much attention due to their diverse biological activities.…”

Organocatalytic enantioselective synthesis of dihydronaphthofurans and dihydrobenzofurans: reaction development and insights into stereoselectivity

“…In both studies, crucial issues such as long reaction times, high catalyst loading, and low temperature conditions needed improvement. Herein, we report our comprehensive work to construct DHN and DHB cores catalyzed by sterically encumbered amine substituted squaramide type bifunctional organocatalysts, [29][30][31][32][33] with a short reaction time, low catalyst loading, and excellent enantioselectivity, and at ambient temperature.…”

Recyclable Organocatalysts in Asymmetric Synthesis

“…A great interest has been arised to enhance these precious chiral structures to achieve remarkable results in asymmetric synthesis. [1][2][3][4][5] Countless studies have been done in many different types of reactions such as Michael, [5][6][7][8][9] aldol, [10][11][12][13][14][15][16] Diels-Alder, [17][18][19][20][21] Henry, [22][23][24][25][26][27] aza-Henry, [28][29][30][31][32][33] Friedel-Crafts, [34][35][36][37][38] Povarov, [39][40][41][42] decarboxylative Doebner-Knoevenagel [43,44] reactions and many others. Although asymmetric organocatalysis can be considered as the most successful and easy way to synthesize enantioenriched compounds, [45] one of the most debated drawbacks is the possibility of agglomeration and aggregation due to high catalyst loading in the reactions.…”