A general method for the synthesis of enantiopure aliphatic chain alcohols with established absolute configurations. Part 1. Application of the MαNP acid method to acetylene alcohols

Yamamoto, Yoko; Akagi, Megumi; Shimanuki, Kumiko; Kuwahara, Shunsuke; Watanabe, Masataka; Harada, Nobuyuki

doi:10.1016/j.tetasy.2014.10.007

Cited by 8 publications

(14 citation statements)

References 14 publications

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“…The MαNP acid method has been applied to other acetylene alcohols as shown in Figure 43. In the case of 3-butyn-2-ol, the diastereomers 64a / 64b were separated well as shown in figure 42a (α = 1.20, Rs = 2.09) [60]. The result indicated that acetylene and methyl groups are recognized well by HPLC on silica gel.…”

Section: Use Of 2-methoxy-2-(1-naphthyl)propionic Acid (Mαnp Acid)mentioning

confidence: 89%

“…The result indicated that acetylene and methyl groups are recognized well by HPLC on silica gel. In the case of 5-methyl-1-hexyn-3-ol, the iso -butyl group is longer than the methyl group, and hence esters 65a / 65b were much more largely separated (α = 1.54, Rs = 2.97) [60].…”

Section: Use Of 2-methoxy-2-(1-naphthyl)propionic Acid (Mαnp Acid)mentioning

confidence: 99%

“…It was easy to determine the ACs of these esters by applying the MαNP ester diamagnetic anisotropy method as shown Figure 44 [60]. In both cases, acetylene protons showed positive ∆δ values, while methyl and iso -butyl groups showed negative ∆δ values.…”

Section: Use Of 2-methoxy-2-(1-naphthyl)propionic Acid (Mαnp Acid)mentioning

confidence: 99%

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HPLC Separation of Diastereomers: Chiral Molecular Tools Useful for the Preparation of Enantiopure Compounds and Simultaneous Determination of Their Absolute Configurations

Harada

2016

Molecules

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Abstract:To obtain enantiopure compounds, the so-called chiral high performance liquid chromatography (HPLC) method, i.e., HPLC using a chiral stationary phase, is very useful, as reviewed in the present Special Issue. On the other hand, normal HPLC (on silica gel) separation of diastereomers is also useful for the preparation of enantiopure compounds and also for the simultaneous determination of their absolute configurations (ACs). The author and coworkers have developed some chiral molecular tools, e.g., camphorsultam dichlorophthalic acid (CSDP acid), 2-methoxy-2-(1-naphthyl)propionic acid (MαNP acid), and others suitable for this purpose. For example, a racemic alcohol is esterified with (S)-(+)-MαNP acid, yielding diastereomeric esters, which are easily separable by HPLC on silica gel. The ACs of the obtained enantiopure MαNP esters can be determined by the 1 H-NMR diamagnetic anisotropy method. In addition, MαNP or CSDP esters have a high probability of giving single crystals suitable for X-ray crystallography. From the X-ray Oak Ridge thermal ellipsoid plot (ORTEP) drawing, the AC of the alcohol part can be unambiguously determined because the AC of the acid part is already known. The hydrolysis of MαNP or CSDP esters yields enantiopure alcohols with the established ACs. The mechanism and application examples of these methods are explained.

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Section: Use Of 2-methoxy-2-(1-naphthyl)propionic Acid (Mαnp Acid)mentioning

confidence: 89%

Section: Use Of 2-methoxy-2-(1-naphthyl)propionic Acid (Mαnp Acid)mentioning

confidence: 99%

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HPLC Separation of Diastereomers: Chiral Molecular Tools Useful for the Preparation of Enantiopure Compounds and Simultaneous Determination of Their Absolute Configurations

Harada

2016

Molecules

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“…To our knowledge, the first asymmetric catalyst of such kind is reported by Yamamoto et al [40], who designed ruthenium complexes derived from spirocyclic C-arylribosides. Shortly after, cyclopentadienone metal complexes with different substituents on the 2,5-positions, and with an enantiopure carbon center in the cyclic backbone of the ligand were developed by the group of Wills [25,41].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Catalytic Application of Knölker-Type Iron Complexes with a Novel Asymmetric Cyclopentadienone Ligand Design

et al. 2019

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Asymmetric catalysis is an essential tool in modern chemistry, but increasing environmental concerns demand the development of new catalysts based on cheap, abundant, and less toxic iron. As a result, Knölker-type catalysts have emerged as a promising class of iron catalysts for various chemical transformations, notably the hydrogenation of carbonyls and imines, while asymmetric versions are still under exploration to achieve optimal enantio-selectivities. In this work, we report a novel asymmetric design of a Knölker-type catalyst, in which the C2-rotational symmetric cyclopentadienone ligand possesses chiral substituents on the 2- and 5-positions near the active site. Four examples of the highly modular catalyst design were synthesized via standard organic procedures, and their structures were confirmed with NMR, IR, MS, and polarimetry analysis. Density functional theory (DFT) calculations were conducted to elucidate the spatial conformation of the catalysts, and therewith to rationalize the influence of structural alterations. Transfer- and H2-mediated hydrogenations were successfully established, leading to appreciable enantiomeric excesses (ee) values up to 70%. Amongst all reported Knölker-type catalysts, our catalyst design achieves one of the highest ee values for hydrogenation of acetophenone and related compounds.

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“…To prepare enantiopure compounds, we have developed the MaNP acid resolution method, [1][2][3][4][5][6][7][8][9][10][11][12] where (S)-(+)-2-methoxy-2-(1-naphthyl)propionic acid 1 (MaNP acid, Fig. 1) is reacted with a racemic secondary alcohol to yield diastereomeric esters, which are readily separable by HPLC on silica gel.…”

Section: Introductionmentioning

confidence: 99%

Application of the modified 2-methoxy-2-(1-naphthyl)propionic (MαNP) acid method to steroidal alcohols and the most efficient HPLC separation found in diastereomeric MαNP esters

Kasai

Harada

2015

Tetrahedron: Asymmetry

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A general method for the synthesis of enantiopure aliphatic chain alcohols with established absolute configurations. Part 1. Application of the MαNP acid method to acetylene alcohols

Cited by 8 publications

References 14 publications

HPLC Separation of Diastereomers: Chiral Molecular Tools Useful for the Preparation of Enantiopure Compounds and Simultaneous Determination of Their Absolute Configurations

HPLC Separation of Diastereomers: Chiral Molecular Tools Useful for the Preparation of Enantiopure Compounds and Simultaneous Determination of Their Absolute Configurations

Synthesis and Catalytic Application of Knölker-Type Iron Complexes with a Novel Asymmetric Cyclopentadienone Ligand Design

Application of the modified 2-methoxy-2-(1-naphthyl)propionic (MαNP) acid method to steroidal alcohols and the most efficient HPLC separation found in diastereomeric MαNP esters

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