Arylacetic acid derivatization of 2,3- and internal erythro-squalene diols. Separation and absolute configuration determination |
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Authors: | José-Luis Abad Francisco Camps |
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Institution: | Department of Biological Organic Chemistry, IIQAB-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain |
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Abstract: | We have studied a new approach for the resolution and absolute configuration determination of the enantiomers of squalene diols as intermediate precursors in the chemical synthesis of different squalene oxides (SOs); (3R)- and (3S)-2,3-SO, (6R,7R)- and (6S,7S)-6,7-SO, and (10R,11R)- and (10S,11S)-10,11-SO. Monoderivatization of the corresponding racemic squalene diol intermediates with pure stereoisomers of (S)-(+)-methoxyphenyl acetic acid ((S)-(+)-MPA), (S)-(+)-9-anthrylmethoxyacetic acid ((S)-(+)-9-AMA) and (S)-(+)-acetoxyphenylacetic acid ((S)-(+)-APA) afforded the diastereomeric esters which could be easily separated by column flash chromatography with silica gel. In addition, the absolute configuration for these diastereoisomers of the derivatized diols was advantageously inferred from 1H NMR data according to the models depicted for these derivatizing chiral agents. In order to demonstrate the absolute configuration assignment of the different stereoisomers, (S)-(+)-AMA showed the larger Δδ by 1H NMR, however, (S)-(+)-MPA esters were much more stable derivatives. |
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Keywords: | Squalene oxides Squalene diols Resolution Enantiomers Derivatization Arylacetic acids |
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