Basic character of rare earth metal alkoxides. Utilization in catalytic carbon-carbon bond-forming reactions and catalytic asymmetric nitroaldol reactions

Recent developments in enantioselective lanthanide-catalyzed transformations

“…Since the first highly enantioselective nitroaldol or Henry reaction reported by Shibasaki et al that was based on the use of heterobimetallic La/Li/BINOL complex [47], this group has developed a series of other lanthanide/alkali metal complexes of this type to be applied in these reactions among others. As a recent example, an heterogeneous heterobimetallic Nd/Na complex 80 was prepared by mixing amide-based ligand 81, Nd 5 O(Oi-Pr) 13 , and NaHMDS in a 2:1:2 ratio in the presence of nitroethane and THF to afford a white suspension, which was further centrifuged to isoScheme 17.…”

“…Nitroaldol reaction of 4-nitro-1-butene with a functionalized a,b-unsaturated aldehyde catalyzed by heterobimetallic Nd/Na/81 complex, and synthesis of zanamivir [47].…”

Development of Atom-Economical Catalytic Asymmetric Reactions under Proton Transfer Conditions: Construction of Tetrasubstituted Stereogenic Centers and Their Application to Therapeutics

“…[40][41][42][43] Almost 100 years have passed since the discovery of the transformation before the reaction was rendered enantioselective in a catalytic manner in 1992 using a LaLi 3 (binaphthoxide) 3 (LLB) catalyst. 44) Since then, catalytic asymmetric nitroaldol reactions have emerged as a useful protocol for the rapid assembly of enantioenriched 1,2-nitro alkanols, which allows for direct access to synthetically versatile 1,2-amino alcohols. Although numerous catalysts for the catalytic asymmetric nitroaldol reactions of nitromethane have been found, progress toward catalytic enantio-and diastereoselective nitroaldol reactions using other nitroalkanes has been limited, except for a few sporadic reports.…”

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].…”