Microbiological Reduction Ofcarbonyl Groupings: Preparation of Stereoisomers Acyclic Chiral α-Diols

Bel-Rhlid, Rachid; Fauve, A.; Renard, Marcel; Veschambre, H.

doi:10.3109/10242429209065251

Cited by 24 publications

(9 citation statements)

References 30 publications

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“…The absolute stereochemistry was confirmed by ozonolysis of the alkene 32 and measurement of the optical rotation of the resulting (S)-3-hydroxypent-2-one {[a] 25 D 48 (c 0.05, CHCl 3 ); lit. : [30] [a] 52 (c 7, CHCl 3 )}. Benzylation of the allylic alcohol 32 with NaH/ THF was capricious and often did not proceed to completion even after extended reaction time.…”

Section: Resultsmentioning

confidence: 99%

The Synthesis of (+)-Allopumiliotoxin 323B′

Tan¹,

Holmes²

2001

Chem. Eur. J.

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This paper describes the synthesis of (+)-allopumiliotoxin 323B' (1) using the intramolecular [3 + 2]-cycloaddition reaction of the (Z)-N-alkenylnitrone 4. This synthesis began with (R)-tert-butyl-3-hydroxy-pent-4-enoate [(R)-13] which was obtained by enzymatic resolution with Amano PS lipase. A series of manipulations gave intermediate 17 and in situ coupling with 4-benzoyloxybutanal lead to the (Z)-N-alkenylnitrone 4 which underwent an intramolecular [3 + 2]-cycloaddition reaction to give the isoxazolidine 3 as the major cycloadduct. Isoxazolidine 3 provided the piperidinone 24 which upon diastereofacial selective addition of MeMgBr gave the required tertiary alcohol 25. Formation of the indolizidine core 2 was achieved by an intramolecular S(N)2 reaction. The side chain was assembled from a Wittig reaction between the phosphorane 8 and the enantiomerically pure aldehyde 9. Further modifications afforded the aldehyde 7 which underwent an aldol condensation with the potassium enolate of the indolizidone core 2. Dehydration gave the enone 37 which was converted into the anti-diol 38 by intramolecular hydride reduction. Finally, deprotection of the BOM protecting group gave (+)-allopumiliotoxin 323B' (1).

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Section: Resultsmentioning

confidence: 99%

The Synthesis of (+)-Allopumiliotoxin 323B′

Tan¹,

Holmes²

2001

Chem. Eur. J.

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“…Lipase‐catalysed racemic resolution of 2‐hydroxy ketones12 has also been applied to aliphatic acyloins,13a together with other enzymatic approaches such as diketone reductions 13b–13d. The use of aliphatic aldehydes as substrates in benzoin‐type condensations provides access to enantiomerically pure acyloins in 100 % theoretical yield.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Synthesis of Aliphatic 2‐Hydroxy Ketones by Enzymatic Carboligation of Aldehydes

et al. 2007

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Keywords: Enzyme catalysis / Carboligation / Benzaldehyde lyase / Benzoylformate decarboxylase / Aldehydes / 2-Hydroxy ketonesBenzaldehyde lyase (BAL) and benzoylformate decarboxylase (BFD) catalyse the asymmetric ligation of aliphatic aldehydes to afford enantiomerically enriched 2-hydroxy ketones. Carboligation of linear aldehydes with both enzymes results in high levels of conversion and in enantioselectivities of up to 80 % ee. In cases involving branched ali-

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“…The most common approach so far has been the reduction of 1,2-diketones either with enzymes or by microbial reduction with whole-cell systems. [1,4,21,22] Frequently encountered drawbacks of these methods are overreduction to diols and also a lack of regioselectivity, yielding two regioisomeric acyloins. A reductive resolution of α-hydroxy ketones to give enantiopure syn diols and chiral acyloins, albeit one resulting in a relatively low isolated yield of the optically pure acyloin, has also been described.…”

Section: Introductionmentioning

confidence: 99%

A New Route to Protected Acyloins and Their Enzymatic Resolution with Lipases

et al. 2004

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A series of 16 different 3-acyloxy methyl ketones, the acyloin acetates and butyrates (±)-5, was synthesised by a straightforward new method through alkylation of tert-butyl 2-acyloxyacetoacetates 3, followed by chemoselective dealkoxycarbonylation of the tert-butyloxycarbonyl group in the presence of other ester groups. Subsequent hydrolysis of (±)-5 can be achieved with base to give racemic acyloins 6, or with lipase catalysis to afford the corresponding non-racemic acyloins (S)-6. The remaining (R)-acyloin esters 5 can be ra-

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Microbiological Reduction Ofcarbonyl Groupings: Preparation of Stereoisomers Acyclic Chiral α-Diols

Cited by 24 publications

References 30 publications

The Synthesis of (+)-Allopumiliotoxin 323B′

The Synthesis of (+)-Allopumiliotoxin 323B′

Asymmetric Synthesis of Aliphatic 2‐Hydroxy Ketones by Enzymatic Carboligation of Aldehydes

A New Route to Protected Acyloins and Their Enzymatic Resolution with Lipases

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