Synthesis of novel chiral Schiff-base ligands and their application in asymmetric nitro aldol (Henry) reaction

Chiral Schiff-bases 3a-f based on ferrocene were designed and synthesized using solvent-free methods by mixing ferrocene carbaldehyde 1 with amino alcohols and amines 2a-f under microwave irradiation and classical method for the enantioselective nitroaldol (Henry) reaction. The Schiff-bases were obtained in shorter reaction times and improved yield under microwave irradiation method over classical method. The highest enantioselectivity was observed in ligand 3e (95% ee) when CH(2)Cl(2) was used as solvent.

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“…Asymmetric Henry Reaction was performed according to our previous method procedure published in literature 27, 29…”

Section: Methodsmentioning

confidence: 99%

Solvent‐free synthesis of chiral Schiff‐base ligands based on ferrocene under microwave irradiation and application to enantioselective nitroaldol (Henry) reaction

2011

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“…Initially, C 2 -symmetric di- aldehyde was prepared according to the procedure described in the literature. 26 The 2 chiral amines, (R) -α -phenylethylamine and (R)-α -(1-naphthyl)ethylamine, were used as chiral sources for synthesis of diamines 1 and 2 (Scheme 1). The reactions of the dialdehyde with the 2 chiral amines in MeOH following by treatment of reactions mixtures with NaBH 4 gave C 2 -symmetric chiral diamines (1 and 2) with quantitative yields.…”

Section: Synthesismentioning

confidence: 99%

C2-Symmetric chiral diamine ligands for enantiomeric recognition of amino acid esters and mandelic acid by proton NMR titration method

Aral¹,

Aral

Çolak³

et al. 2013

Turk J Chem

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Two novel C 2 -symmetric chiral diamines containing α -phenylethyl and α -(1-naphthyl)ethyl chiral subunits were prepared with quantitative yields. Enantiomeric recognition properties of these simple structured diamine ligands towards D-and L-amino acid esters and D-and L-mandelic acid were examined by the 1 H NMR titration method.These ligands exhibited strong complexation (with K f up to 2481 M −1 ) and good enantioselectivity (up to K L /K D = 4.08) towards the mandelic acid enantiomers. The results show that simple structured and easily accessible acyclic C 2 -symmetrical compounds can also be used for enantiomeric recognition of racemic amino acids and mandelic acid in addition to complex molecules such as crown ethers and other cyclic molecules.

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“…Shibasaki has reported the first asymmetric version of nitroaldol reaction in 1992 [3][4][5][6][7][8][9][10][11]. Since then various metals [3][4][5][6][7][12][13][14][15][16][17] and non-metal based catalysts [18,19] have been investigated for the asymmetric nitroaldol reaction with chiral ligands such as BINOL [5,10,20], amino alcohol [21,22], bis(oxazoline) [23][24][25][26][27][28][29][30][31], bis(thiazoline) [32], bis(imidazoline) [33][34][35], sulfonyl diamine [36], salen [37][38][39][40], Schiff bases [41][42][43][44]…”

Section: Introductionmentioning

confidence: 99%

Chiral Cu(II) Complexes as Recyclable Catalysts for Asymmetric Nitroaldol (Henry) Reaction in Ionic Liquids as Greener Reaction Media

et al. 2010

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Chiral Cu (II) complexes generated in situ from C 2 -symmetric chiral secondary bis-amines 1 0 -4 0 based on 1,2-diaminocyclohexane structure having H, t-Bu and Cl substituents at 3, 3 0 , 4, 4 0 and 5, 5 0 with copper acetate. They were used as catalysts for an environmentally benign protocol for highly enantioselective nitroaldol reaction of various aldehydes with nitromethane in the presence of different ionic liquids as a greener reaction medium at 0°C. Excellent yields (up to 90% with respect to aldehyde) of b-nitroalcohols with high enantioselectivity (ee, up to 94%) was achieved when [emim]BF 4 was used as ionic liquid. The present ionic liquid mediated nitroaldol protocol is recyclable (up to five cycles) with no significant loss in its performance.

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Synthesis of novel chiral Schiff-base ligands and their application in asymmetric nitro aldol (Henry) reaction

Cited by 53 publications

References 33 publications

Solvent‐free synthesis of chiral Schiff‐base ligands based on ferrocene under microwave irradiation and application to enantioselective nitroaldol (Henry) reaction

Solvent‐free synthesis of chiral Schiff‐base ligands based on ferrocene under microwave irradiation and application to enantioselective nitroaldol (Henry) reaction

C2-Symmetric chiral diamine ligands for enantiomeric recognition of amino acid esters and mandelic acid by proton NMR titration method

Chiral Cu(II) Complexes as Recyclable Catalysts for Asymmetric Nitroaldol (Henry) Reaction in Ionic Liquids as Greener Reaction Media

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