Asymmetric Reduction of Acetoacetic Ester by Chirally Modified Sodium Borohydride

Polyak, F. D.; Solodin, I. V.; Dorofeeva, T. V.

doi:10.1080/00397919108021032

Cited by 14 publications

(4 citation statements)

References 9 publications

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“…The use of NaBH 4 modified with optically active carboxylic acids was investigated by Nasipuri [21] and Bianchi [22] using mandelic and lactic acids, while Adams [23] and Yamazaki [24] utilized tartaric acid. Additional work by Yatagai [25,26] and Polyak [27] with tartaric acid-modified NaBH 4 gave moderate ee values for the reduction of some α-and β-substituted ketones, though enantioselectivities were lower for simple, unmodified ketones.…”

Section: Introductionmentioning

confidence: 93%

Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH₄ and TarB‐NO₂: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System

et al. 2005

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High enantioselectivities are obtained for the reduction of a series of ketones using the inexpensive and mild reducing agent NaBH4 with TarB‐NO2 (1). This easily prepared tartaric acid‐based reagent combines a Lewis acid with carboxylic acids in a single bifunctional reagent. When combined with NaBH4, the resulting chiral acyloxyborohydride mediates the reduction of aromatic ketones to provide the product alcohols in enantiomeric excesses of 93–98 %. Several aliphatic ketones were also reduced with moderate to excellent enantioselectivity. A unique mechanism is provided with supporting calculations for the proposed active species and transition state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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Section: Introductionmentioning

confidence: 93%

Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH₄ and TarB‐NO₂: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System

et al. 2005

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“…According to Yatagai the NaBH 4 /tartaric acid complex was able to selectively reduce hindered ketones such as α-ketoesters, β-ketoesters, and functionalized acetophenones with good ee. Polyak, however, was unable to reproduce Yatagai's results and achieved much lower ee's using the same reagents (eq 1) …”

Section: Use Of Tartaric Acid With Nabh4 In Asymmetric Reductionmentioning

confidence: 95%

“…Polyak, however, was unable to reproduce Yatagai's results and achieved much lower ee's using the same reagents (eq 1). 48 Nozaki combined (L)-tartaric acid and boronic acid to form a chiral Lewis acid reducing agent. 49 The bisboronate ester showed promising results in the reduction of aminosubstituted aryl ketones.…”

Section: Use Of Tartaric Acid With Nabh 4 In Asymmetric Reductionmentioning

confidence: 99%

Asymmetric Reductions Involving Borohydrides: A Practical Asymmetric Reduction of Ketones Mediated by (l)-TarB−NO₂: A Chiral Lewis Acid

Kim

Suri

Cordes

et al. 2006

Org. Process Res. Dev.

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The asymmetric reduction of prochiral ketones has been achieved through a myriad of different methods. Early reductions gave low to moderate enantiomeric excesses (ee's), but more modern reagents have led to dramatic increases in enantioselectivity. The development of (L)-TarB-NO 2 boronic ester is extensively reviewed in the context of other well-known asymmetric reducing reagents. In combination with NaBH 4 , the chiral intermediate is able to reduce prochiral ketones to optically active secondary alcohols in ee's as high as 99% and can be easily recovered under basic conditions.

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“…Generally, NaBH 4 is used as a mild and selective reducing agent, and reducing reagents modified with chiral sources are very useful for the asymmetric reduction of ketones. For example, use of phase transfer catalysts, protein, amino acids, monosaccharide derivatives, and carboxylic acids 12f, as chiral sources have been reported in ketone reductions. This information motivated us to study the asymmetric reduction of 3 with NaBH 4 and chiral sources.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Reduction of a 1,5-Benzothiazepine Derivative with Sodium Borohydride−(S)-α-Amino Acids: An Efficient Synthesis of a Key Intermediate of Diltiazem

et al. 1996

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A key intermediate of diltiazem synthesis, (2S,3S)-2,3-dihydro-3-hydroxy-2-(4-methoxyphenyl)-1,5-benzothiazepin-4(5H)-one [(2S,3S)-1], has been efficiently synthesized by an asymmetric reduction of the prochiral ketone, 2-(4-methoxyphenyl)-1,5-benzothiazepine-3,4(2H,5H)-dione (3), with NaBH4 and chiral α-amino acids. As the chiral sources, β-branched-chain amino acids, such as (S)-valine, (S)-isoleucine, and (S)-tert-leucine, were found to be effective. In particular, using (S)-tert-leucine as a ligand resulted in the formation of (2S,3S)-1 with excellent enantioselectivity. (95% ee for cis-isomers). The addition of AcOH to the reaction permitted further improvement of both conversion and stereoselectivity. As a result, optically pure (2S,3S)-1 could be isolated in 86% yield. This asymmetric reduction proceeded via dynamic kinetic resolution and made it possible to control the two adjacent asymmetric carbons through keto−enol tautomerism.

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Asymmetric Reduction of Acetoacetic Ester by Chirally Modified Sodium Borohydride

Cited by 14 publications

References 9 publications

Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH₄ and TarB‐NO₂: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System

Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH₄ and TarB‐NO₂: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System

Asymmetric Reductions Involving Borohydrides: A Practical Asymmetric Reduction of Ketones Mediated by (l)-TarB−NO₂: A Chiral Lewis Acid

Asymmetric Reduction of a 1,5-Benzothiazepine Derivative with Sodium Borohydride−(S)-α-Amino Acids: An Efficient Synthesis of a Key Intermediate of Diltiazem

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Asymmetric Reduction of Acetoacetic Ester by Chirally Modified Sodium Borohydride

Cited by 14 publications

References 9 publications

Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH4 and TarB‐NO2: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System

Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH4 and TarB‐NO2: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System

Asymmetric Reductions Involving Borohydrides: A Practical Asymmetric Reduction of Ketones Mediated by (l)-TarB−NO2: A Chiral Lewis Acid

Asymmetric Reduction of a 1,5-Benzothiazepine Derivative with Sodium Borohydride−(S)-α-Amino Acids: An Efficient Synthesis of a Key Intermediate of Diltiazem

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Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH₄ and TarB‐NO₂: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System

Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH₄ and TarB‐NO₂: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System

Asymmetric Reductions Involving Borohydrides: A Practical Asymmetric Reduction of Ketones Mediated by (l)-TarB−NO₂: A Chiral Lewis Acid