Functionalized Nitroalkanes as Useful Reagents for Alkyl Anion Synthons

Rosini, Goffredo; Ballini, Roberto

doi:10.1055/s-1988-27726

Cited by 341 publications

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“…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].…”

Section: Abstract: Imidazolylpyridines Catalysis Copper Complex Almentioning

confidence: 99%

“…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]. 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].…”

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confidence: 99%

“…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].…”

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

et al. 2006

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New chiral nitrogen ligands based on the substituted mono-and bis(imidazolyl)pyridines have been prepared and characterised. Their complexes with cupric acetate were used as catalysts in the nitroaldolisation reaction. In the case of optically pure complexes of mono(imidazolyl)pyridine, the isolated products were 2-nitro-1-(2-nitrophenyl)ethanols or 2-nitro-1-(4-nitrophenyl)ethanols in overall yields of 49-93 % and with the maximum enantiomeric excess of 15.6 %. The complexes of bis(imidazolyl)pyridine also catalyse the nitroaldol reaction, the yields being 64-90 %, but with zero enantioselective excess. Keywords: imidazolylpyridines, catalysis, copper complex, aldolisation reactionIn recent years, the development of new chiral ligands and their complexes with transition metals has been dynamically increasing [1,2]. These complexes are predominantly exploited as homogeneous catalysts within a broad spectrum of asymmetrical syntheses [3]. 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]. 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]. In the previous paper, the synthesis and characterisation of (R,S)-, (R,R)-, (S,S)-2,6-bis(4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-on-2-yl)pyridines and their complexes with ferric chloride was described [23].The aim of the present paper is the synthesis and characterisation of new chiral optically pure 2-(4-isopropyl-1,4-dimethyl-4,5-dihydro-1H-imidazol-5-on-2-yl)pyridine (I ) and 2,6-bis(4-isopropyl-1,4-dimethyl-4,5-dihydro-1H-imidazol-5-on-2-yl)pyridine (II ). These ligands were prepared by Nmethylation of the optically pure 2-(4-isopropyl-4-methyl-4,5-dihydro-1Himidazol-5-on-2-yl)pyridine or 2,6-bis(4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-on-2-yl)pyridine (Scheme 1).

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Section: Abstract: Imidazolylpyridines Catalysis Copper Complex Almentioning

confidence: 99%

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

et al. 2006

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“…These are recognized as versatile synthetic building blocks which can be either transformed into biologically active compounds such as tetrahydropyrans, amino acids, pyrrolidines and lactones [7][8][9], or readily converted into other functionalities such as ketones, amines, carboxylic acids, nitrile oxides, etc. [10][11][12][13]. Extensive studies have been devoted to the development of catalytic systems for Michael additions of various active methines such as pronucleophiles to nitroalkenes including cinchona organocatalysts [14], enzymes [15], various chiral amines [16,17], transition metal-free organocatalysts [18][19][20] and chiral metal complexes [21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

A Greener, Efficient Approach to Michael Addition of Barbituric Acid to Nitroalkene in Aqueous Diethylamine Medium

et al. 2014

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An efficient method for the synthesis of a variety of pyrimidine derivatives 3a-t by reaction of barbituric acids 1a,b as Michael donor with nitroalkenes 2a-k as Michael acceptor using an aqueous medium and diethylamine is described. This 1,4-addition strategy offers several advantages, such as using an economic and environmentally benign reaction media, high yields, versatility, and shorter reaction times. The synthesized compounds were identified by 1 H-NMR, 13 C-NMR, CHN, IR, and MS. The structure of compound 3a was further confirmed by single crystal X-ray structure determination.

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“…It is the base catalyzed addition of a nitroalkane to a carbonyl compound and gives access to various substrates. The nitroaldol product, a 2-nitroalkanol, can be easily transferred into other substance classes like nitro alkenes, 2-amino alcohols and -nitro ketones [1,2]. All these substance classes are highly functionalized organic molecules and thus very useful in natural product synthesis.…”

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confidence: 99%