Anomaly in the modified Mosher's method: Absolute configurations of some marine cembranolides

Kusumi, Takenori; Fujita, Yoshiji; Ohtani, Ikuko I.; Kakisawa, Hiroshi

doi:10.1016/0040-4039(91)80650-u

Cited by 101 publications

(87 citation statements)

References 11 publications

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“…Although we examined only the 6-membered ring in this study, the concept of this method should be applicable to systems of other ring sizes, for example 5-, 7-, 10-membered rings or more. However, care must be taken for the conformation and the ring size of the molecule since the modified Mosher's method is not applicable to the sterically hindered alcohols 3,4 and the spatial orientation of the protons in question might be unclear when the ring is large, about a 10-membered size or more.…”

Section: Cyclic 13-diolsmentioning

confidence: 99%

“…If the Dd L and Dd R values are irregularly distributed, the data are not valid in any case, as previously reported. 3,4 This method is complementary to the CD exciton chirality method for 1,3-diols. Harada et al 17 reported that the CD spectra of acyclic anti-l,3-dibenzoates and 1,3-dibenzoates with a single chiral center show exciton split Cotton effects, from the sign of which the absolute configuration can be determined, whereas in the case of syn-1,3-dibenzoates the CD spectra show a weak single Cotton effect, instead of exciton split Cotton effects.…”

Section: Acyclic 13-diolsmentioning

confidence: 99%

“…The reaction mixture was stirred for 30 min and quenched by the addition of sat. NH 4 Cl aq. After extraction with ethyl acetate, the organic layer was washed with brine, dried over magnesium sulfate, and filtered.…”

Section: Generalmentioning

confidence: 99%

“…3 It is also advantageous to have a self-examination mechanism, recognizing whether the observed data are valid or not. 4 Accordingly, this method has been extensively used over the last decade, thus establishing one of the most reliable and effective methods for determining the absolute configuration of secondary alcohols. 5 This method is also applicable to amines and amino acids.…”

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confidence: 99%

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Determination of absolute configuration of 1,3‐diols by the modified Mosher's method using their di‐MTPA esters

et al. 2001

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1,3-Diols are frequently involved in biologically important compounds and, therefore, determination of the stereochemistry of these structural elements, in particular those in acyclic systems, has been one of the focuses of attention in natural products chemistry. The modified Mosher's method, commonly used for the determination of the absolute configuration of secondary alcohols, was applied to determine the absolute configuration of 1,3-diols with their di-MTPA esters. Several epimeric pairs of syn- and anti-1,3-diols with known absolute configurations were converted to the corresponding di-MTPA esters and the iDelta;delta values were then calculated. For the acyclic syn-1,3-diols, the iDelta;delta values were systematically arranged as predicted from the basic concept of the modified Mosher's method, demonstrating that the method is valid for these compounds. In contrast, the iDelta;delta values were irregularly arranged for the acyclic anti-1,3-diols and, accordingly, this method is not valid for these cases. These results are complementary to those of the previously reported CD exciton chirality method and, hence, the combined use of the modified Mosher's method and the CD exciton chirality method can determine the absolute configuration of the acyclic 1,3-diols. Also, this method is successfully applicable to cyclic 1,3-diols irrespective of their relative stereochemistry.

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Section: Cyclic 13-diolsmentioning

confidence: 99%

Section: Acyclic 13-diolsmentioning

confidence: 99%

Section: Generalmentioning

confidence: 99%

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confidence: 99%

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Determination of absolute configuration of 1,3‐diols by the modified Mosher's method using their di‐MTPA esters

et al. 2001

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“…The optical purity of the AD product 13 was at least 96% ee by chiral GC analysis. The 6S stereochemistry of 13 was con®rmed by Kusumi's modi®ed Mosher method 13 in 99% ee. This tendency of lower yield and less enantioselectivity of AD-mix a compared to b has already been reported for other substrates by Sharpless.…”

Section: Methodsmentioning

confidence: 99%

The Volatile Constituents of the Coffee Flower (Coffea arabica L.)

et al. 1997

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Although coee beans have been well studied, the volatile constituents of the coee¯ower have not previously been investigated. An extract of coee¯ower (Coea arabica L.) was analyzed by GC±MS and found to contain a signi®cant number of nitrogen-containing aromatic compounds as well as phenylethane derivatives. The novel epoxygeraniols (2,3-epoxygeraniol and 6,7-epoxygeraniol) were also detected as minor components. These epoxides were estimated to be an approximately equal mixture of both enantiomers by chiral GC analysis. Optically active 2,3-epoxygeraniols were synthesized by Sharpless's asymmetric epoxydation (AE), and 6,7-epoxygeraniols were prepared utilizing Sharpless's asymmetric dihydroxylation (AD) as a key step in high optical purities (96±99% ee). Epoxygeraniols were found to possess rosy and muguet-like aromas reminiscent of the living¯ower. Considerable dierences of aroma were perceived between the enantiomers. # 1997 by John Wiley & Sons, Ltd.

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Mosher's Acid

2010

Comprehensive Organic Name Reactions and Reagents

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The α‐methoxy‐α‐(trifluoromethyl) phenylacetic acid (MTPA) is generally referred to as the Mosher acid and it has been widely used in the determination of enantiomeric excess of chiral molecules. Its derivative (i.e., acyl chloride) for the preparation of ester or amide from primary or secondary alcohol or amine is known as Mosher's reagent, and the corresponding ester is called the Mosher ester. Several characteristics and usages of the Mosher acid have been presented. It has been found that while the chemical shift of one group attached to the carbinyl location in (R)‐(+)‐MTPA ester moves upfield, the chemical shift of the other group exclusively goes downfield; the reverse movement of chemical shifts are observed for the same carbinol in (S)‐(‐)‐MTPA ester. Also to determine the absolute configuration of a given alcohol, both (R)‐(+)‐MTPA and (S)‐(‐)‐MTPA esters are prepared, and different NMRspectra are measured. This compound has wide application in determination of enantiomeric excess and the absolute configuration of chiral compounds.

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Anomaly in the modified Mosher's method: Absolute configurations of some marine cembranolides

Cited by 101 publications

References 11 publications

Determination of absolute configuration of 1,3‐diols by the modified Mosher's method using their di‐MTPA esters

Determination of absolute configuration of 1,3‐diols by the modified Mosher's method using their di‐MTPA esters

The Volatile Constituents of the Coffee Flower (Coffea arabica L.)

Mosher's Acid

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