Constructing densely functionalized Hajos–Parrish-type ketones with six contiguous stereogenic centers and two quaternary carbons in a formal [2 + 2 + 2] cycloaddition cascade

Peng, Chieh-Hung; Hong, Bor‐Cherng; Raja, Arun; Chang, Chun-Wei; Lee, Gene‐Hsiang

doi:10.1039/c6ra22430j

Cited by 6 publications

(3 citation statements)

References 71 publications

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“…The SDE refers to the spontaneous fractionation of nonracemic material into enantioenriched and depleted fractions when any physicochemical process is applied under totally achiral conditions [17][18][19]. The purification or separation of nonracemic sample by fractional crystallization and sublimation based on the SDE principle can be recalled from very early times, and is still of interest for many researchers [20][21][22][23]. Additionally, since the seminal works of P. A. Crooks [24] and E. Gil-Av [25], the SDE on different types of achiral chromatography including routine, gravity-driven column chromatography, medium pressure liquid chromatography (MPLC), high-performance liquid chromatography (HPLC) and gas chromatography (GC) has been intensively studied [26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Copper (II) Ions Induced Self-Disproportionation of Enantiomers in Capillary Electrophoresis for the Quantification of Atenolol Enantiomers

2023

Molecules

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Despite the fact that the self-disproportionation of enantiomers (SDE) has been found for several decades and has been widely used in crystallization, sublimation and chromatography for the purification or separation of nonracemic compounds, the phenomenon of SDE in capillary electrophoresis (CE) has never been reported up to now. Here, a new approach to separate enantiomers in CE based on SDE was demonstrated by introducing copper (II) ions into the separation media. The enantiomers of atenolol interact with copper ions to produce positively charged complexes with different electrophoretic mobilities from the single molecules. The dynamic equilibrium between homo- or heterochiral complexes (associates) and single molecules of atenolol enantiomers supports the manifestation of SDE. Different mobilities of the single molecules and associates, and different distribution of two enantiomers between the single molecules and associates caused by their different concentrations, produce a net difference in electrodriven migration velocities of the two enantiomers. The relative movement of two enantiomers causes a zone depleted in one enantiomer at the rear end of sample segment, giving a trapezoidal CE curve with a step at the end. Quantification of enantiomers is achieved according to the step height. The analysis does not rely on the use of enantiomerically pure chiral selector and the result agrees with that obtained by conventional chiral CE using a chiral selector.

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Section: Introductionmentioning

confidence: 99%

Copper (II) Ions Induced Self-Disproportionation of Enantiomers in Capillary Electrophoresis for the Quantification of Atenolol Enantiomers

2023

Molecules

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“…As a continuation of our interest in domino organocatalysis reactions and in the course of subsequent study of the cascade Michael reactions (Scheme a,b), we observed a small amount of an unknown product in the reaction of 2-methylcyclopentane-1,3-dione and nitrostyrene with some organocatalysts. In particular, the unknown products increased in quantity when a cinchona primary amine (Q-NH 2 ) was applied as the catalyst (Scheme c).…”

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confidence: 99%

Catalytic 1,2-Rearrangements: Organocatalyzed Michael/Semi-Pinacol-like Rearrangement Cascade of 1,3-Diones and Nitroolefins

et al. 2019

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New types of organocatalytic 1,2-rearrangements, which resemble the Smiles-like or semi-pinacol-like rearrangement, of Michael adducts of 1,3-dicarbonyl-2-alkyl compounds and nitroalkenes have been realized. Unlike the well-known conjugate addition, the reaction affords the 1-phenyl-1-nitroalkanes via unprecedented rearrangement and cascade reactions. Structures of the appropriate products were unambiguously characterized by X-ray crystallography.

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“…[17] Organocatalysts [18] have been successfully employed in the synthesis of steroids.T he proline-mediated intramolecular aldol reaction, reported in 1971, [19] is alandmark discovery in organocatalysis.This approach is effective for the synthesis of the Wieland-Miescher ketone,akey intermediate of the steroid synthesis. [20] Recently,Hong and co-workers reported the one-pot synthesis of as teroid system through organocatalyst-mediated Michael/Michael/aldol/Henry and Michael/ Michael/Henry reactions, [21] whereas Jørgensen and co-workers reported the construction of the steroid structure by using Torgovsd iene via ad ienamine intermediate. [22] List and coworkers reported as hort synthesis of estrone through chiral disulfonimide-mediated Torgov cyclization as ak ey step.…”

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confidence: 99%

Pot Economy in the Total Synthesis of Estradiol Methyl Ether by Using an Organocatalyst

et al. 2017

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Enantioselective total synthesis of estradiol methyl ether has been accomplished in a pot-economical manner using five reaction vessels and four purifications. The key reaction is a diphenylprolinol silyl ether mediated domino Michael/aldol reaction to afford bicyclo[4.3.0]nonane derivatives, containing the A, C, and D rings of steroids, as a single isomer with excellent enantioselectivity. Six reactions such as oxidation, hydrogenation, formation of acid chloride, Friedel-Crafts reaction, deprotection, and reduction can be carried out in the last one-pot sequence.

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Constructing densely functionalized Hajos–Parrish-type ketones with six contiguous stereogenic centers and two quaternary carbons in a formal [2 + 2 + 2] cycloaddition cascade

Abstract: Efficient construction of Hajos–Parrish-type ketones with six contiguous stereogenic centers in a formal [2 + 2 + 2] cycloaddition cascade. The spontaneous resolution of racemic product without the need for chiral agent has been achieved.

Cited by 6 publications

References 71 publications

Copper (II) Ions Induced Self-Disproportionation of Enantiomers in Capillary Electrophoresis for the Quantification of Atenolol Enantiomers

Copper (II) Ions Induced Self-Disproportionation of Enantiomers in Capillary Electrophoresis for the Quantification of Atenolol Enantiomers

Catalytic 1,2-Rearrangements: Organocatalyzed Michael/Semi-Pinacol-like Rearrangement Cascade of 1,3-Diones and Nitroolefins

Pot Economy in the Total Synthesis of Estradiol Methyl Ether by Using an Organocatalyst

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