Convenient Methods to Access Chiral Camphanyl Amine Derivatives by ­Sodium Borohydride Reduction of d-(–)-Camphorquinone Imines

Periasamy, Muthu; Sanjeevakumar, Nalluri; Reddy, Polimera Obula

doi:10.1055/s-0032-1317012

Cited by 13 publications

(19 citation statements)

References 4 publications

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“…7 Also, the chiral camphorylpiperazine derivatives were prepared by condensation of ethylenediamine with optically active camphorquinone. 8 A similar condensation process with 1,2 diaminocyclohexane was also reported. 9 Herein, we report methods for synthesis of piperazine derivatives containing chiral bi-2-napthyl moiety.…”

supporting

confidence: 55%

“…Subsequent condensation of this keto ester (R)-3 with ethylenediamine (4) in anhydrous methanol gave the product (R)-5 in 90% yield. We have observed that similar condensation reactions of (R)-3 with 1,2-diaminobenzene (6) and (2R,3R)-1,2-diaminocyclohexane (8) under reflux conditions furnished cyclic products (R)-7 and (R)-9 in 90% and 88% yield, respectively.…”

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confidence: 89%

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Methods for the Synthesis of Piperazine Derivatives Containing a Chiral Bi-2-naphthyl Moiety

Periasamy

Venkanna²,

Miriyala³

et al. 2019

Synthesis

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Piperazine derivatives containing 1,1′-bi-2-naphthyl moiety were synthesized starting from 2,2′-dimethoxy-1,1′-bi-naphthalene via acylation using ethyl chlorooxoacetate and subsequent condensation with 1,2-diamines followed by reduction of the corresponding dihydro-2-piperazinone intermediate using the NaBH4/I2 reagent system. The corresponding chiral piperazine derivatives containing bi-2-napthyl moiety was synthesized by asymmetric reduction of ethyl dimethoxy-bi-2-naphthyloxoacetate by chiral oxazoborolidine catalyst prepared in situ using S-diphenylprolinol (S-DPP), B(OCH3)3 and H3B·THF. The resulting diols were mesylated and cyclized using 1,2-diamines to obtain the corresponding chiral piperazine derivatives.

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confidence: 55%

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confidence: 89%

Methods for the Synthesis of Piperazine Derivatives Containing a Chiral Bi-2-naphthyl Moiety

Periasamy

Venkanna²,

Miriyala³

et al. 2019

Synthesis

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“…Because the generated mine would be hydrolysed in the presence of water, the anhydrous methanol/DMSO mixed solvents were used as the reaction medium in the reaction between melamine and glutaraldehyde. Besides, in order to enhance the stability of the melamine modified layer, NaBH 4 was adopted as the reductant to convert the unstable imine bond into stabilized amine .…”

Section: Resultsmentioning

confidence: 99%

Counter‐current chromatography melamine‐modified column and its separation mechanism

Quan

Huang

Gong

et al. 2018

J of Separation Science

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In this work, to further verify and develop the novel counter‐current chromatography modified column separate mode, a melamine modified counter‐current chromatography column was prepared. Meanwhile, the modified counter‐current chromatography column was used to separate stevioside and rebaudioside A with the same partition coefficient in chosen solvent system to evaluate its separation efficiency. The results show that because of the presence of intermolecular forces between melamine and model compounds, better separation could be achieved on the modified column while it's almost impossible to be separated on the unmodified column. So the results of this research further show that column modified method is a possible approach to further increase the separation ability of counter‐current chromatography. Take advantage of large sample handing capacity of counter‐current chromatography, the mothed may have great potential to be an efficient method of separation and preparation enantiomer compounds.

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“…Chiral piperazine derivative 4 containing a camphanyl moiety was readily prepared by a recently reported method (Scheme ) 7…”

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confidence: 99%

Enantioselective Synthesis of Both Enantiomers of Chiral Allenes Using Chiral N‐Methylcamphanyl Piperazine Templates

2013

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The reaction of unsubstitued camphanyl‐piperazine 4 with ZnCl2, phenylacetylene, and benzaldehyde in toluene gave the corresponding dipropargylamine (i.e., 15) with opposite configurations at the newly formed stereogenic centres, which, upon reaction with ZnI2 resulted in the formation of a racemic mixture of 1,3‐diphenyl allene in 45 % yield. N‐Methylcamphanyl‐piperazine regioisomer 5, prepared by selective N‐methylation of the NH moiety attached to the stereogenic centre with (S)‐configuration, upon reaction with ZnCl2, phenylacetylene, and benzaldehyde in toluene, gave the corresponding propargylamine in 90 % yield, with an (S)‐configuration at the newly formed stereogenic centre, and upon subsequent reaction with ZnI2, this intermediate gave (R)‐1,3‐diphenyl allene in 52 % yield and with 96 % ee. Reaction of N‐methylcamphanyl‐piperazine isomer 5 with several 1‐alkynes and aldehydes in the presence of ZnBr2 gave the corresponding (R)‐allenes in 40–75 % yield and 79–99 % ee. In contrast, regioisomeric N‐methylcamphanyl‐piperazine 6 reacted with ZnBr2 to give the corresponding (S)‐allenes in 38–71 % yield and with 79–99 % ee. The opposite chiral discriminating abilities of the two NH moieties in camphanyl‐piperazines was confirmed by single‐crystal X‐ray analysis of the propargylamines formed. The results are discussed considering mechanisms involving the in situ formation of alkynylzinc halides, followed by diastereoselective addition to chiral iminium ion derivatives to give the corresponding propargylamines, and subsequent conversion to chiral allenes by an intramolecular 1,5‐hydrogen shift.

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Convenient Methods to Access Chiral Camphanyl Amine Derivatives by Sodium Borohydride Reduction of d-(–)-Camphorquinone Imines

Cited by 13 publications

References 4 publications

Methods for the Synthesis of Piperazine Derivatives Containing a Chiral Bi-2-naphthyl Moiety

Methods for the Synthesis of Piperazine Derivatives Containing a Chiral Bi-2-naphthyl Moiety

Counter‐current chromatography melamine‐modified column and its separation mechanism

Enantioselective Synthesis of Both Enantiomers of Chiral Allenes Using Chiral N‐Methylcamphanyl Piperazine Templates

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Convenient Methods to Access Chiral Camphanyl Amine Derivatives by ­Sodium Borohydride Reduction of d-(–)-Camphorquinone Imines

Cited by 13 publications

References 4 publications

Methods for the Synthesis of Piperazine Derivatives Containing a Chiral Bi-2-naphthyl Moiety

Methods for the Synthesis of Piperazine Derivatives Containing a Chiral Bi-2-naphthyl Moiety

Counter‐current chromatography melamine‐modified column and its separation mechanism

Enantioselective Synthesis of Both Enantio­mers of Chiral Allenes Using Chiral N‐Methylcamphanyl Piperazine Templates

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Convenient Methods to Access Chiral Camphanyl Amine Derivatives by Sodium Borohydride Reduction of d-(–)-Camphorquinone Imines

Enantioselective Synthesis of Both Enantiomers of Chiral Allenes Using Chiral N‐Methylcamphanyl Piperazine Templates