Effect of Ligand Structure on the Zinc-Catalyzed Henry Reaction. Asymmetric Syntheses of (−)-Denopamine and (−)-Arbutamine

Abstract

[reaction: see text] Syntheses of variously modified ligands for the dinuclear zinc catalysts for the asymmetric aldol and nitroaldol (Henry) reactions are reported. Catalytic enantioselective nitroaldol reactions promoted by these modified ligands led to efficient syntheses of the beta-receptor agonists (-)-denopamine and (-)-arbutamine.

Benzotriazole-mediated amidoalkylations of nitroalkanes, nitriles, alkynes and esters

“…Nitronate salts act as carbon nucleophiles in the well-known Michael, 13 Henry, 14 Knoevenagel, 15 and nitro-Mannich reactions, 16 providing valuable derivatives in which the nitro group can be retained, reductively eliminated, or transformed to provide ketones, 17 amines, 18 oximes, 19 or nitriles. 20 Therefore, methodologies to introduce the nitro group into a molecular framework along with other functionalities have gained momentum.…”

Simple Lanthanide Amides [(Me3Si)2N]3Ln(µ‐Cl)Li(THF)3 as Highly Efficient Catalysts for the Nitroaldol Reaction

“…For example, Shibasaki and co-workers 7 for the first time reported nonmetallocene rare earth metal alkoxides as catalysts for the Henry reaction, since then, a series of other nonmetallocene catalysts have been developed for the catalytic Henry reactions, [8][9][10][11][12][13][14][15] and it has been a continuous interest for chemists to develop a new catalytic system applied to this transformation. [10][11][12][13][14][15][16][17][18] More recently, most efforts have been focused on the development of catalytic diastereo- [19][20][21][22][23][24] and enantioselectivity [25][26][27] for Henry reaction.…”

New substituted mono-and bis(imidazolyl)pyridines and their application in nitroaldolisation reaction

“…The ligands prepared in this study on the basis of mono-and bis(imidazolyl)pyridines are formally similar to the ligands with oxazolines "Pymox" [4] and "Pybox" [5], which belong among the best-known and widely applied nitrogen ligands. One of the most advantageous reactions for creating new C-C bonds at mild conditions is nitroaldolisation reaction [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. It is a reaction of carbonyl compound and nitroalkane having α-hydrogen atom, which is usually catalysed by metal complexes in the presence of bases (tertiary amines, sodium acetate) [6][7][8][9][10][11][12].…”

“…It is a reaction of carbonyl compound and nitroalkane having α-hydrogen atom, which is usually catalysed by metal complexes in the presence of bases (tertiary amines, sodium acetate) [6][7][8][9][10][11][12]. Another possibility consists in the catalysis by weak Lewis acids, which are components in complexes with mildly basic ligands (carboxylates) that can act as bases and deprotonate nitroalkane [13][14][15][16][17][18][19][20][21]. The product of nitroaldolisation reaction is β-hydroxynitroalkane, which can further be reduced to 1,2-amino alcohol, can undergo the Neff reaction to give the respective carbonyl compound, or can be dehydrated to nitroalkene [19,22].…”

“…Lower catalytic activity of the complexes comprising N,N,Ntridentate ligand II can be attributed to the steric effects, e.g. compared to complexes derived from 2,6-bis(4-isopropyl-2-oxazolin-2-yl)pyridines used for the same reaction but not containing the two methyl groups situated at the two stereogenic centres [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”