The biocatalytic approach to the preparation of enantiomerically pure chiral building blocks

Santaniello, Enzo; Ferraboschi, Patrizia; Grisenti, Paride; Manzocchi, Ada

doi:10.1021/cr00013a016

Cited by 525 publications

(125 citation statements)

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“…When N-bromosuccinimide (NBS) was used as the electrophile, the reactions successfully proceeded to give 2a (R 1 ϭR 2 ϭH, XϭBr) having the newly formed four chiral centers and other stereoisomers in good yields with fairly good diastereoselective manners (entries 3-5). A lower reaction temperature also gave better results (entries 3 vs. 4) and CH 3 ϭH, XϭBr) as the major products in fairly good yields (entries 7,8). Mixed solvent (CH 3 CN/CH 2 Cl 2 ϭ4/1) was used in entry 7 due to low solubility of 1c to CH 3 CN.…”

Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis by the Intramolecular Haloetherification Reaction of Ene Acetal: Discrimination of Prochiral Dienes in Cyclohexane Systems

Fujioka

Kotoku

Sawama

et al. 2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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Asymmetric synthesis based on the desymmetrization of symmetric compounds is one of the most powerful ways to get optically pure compounds, especially for the substrates having prochiral carbon atom(s), and many methodologies by chemical reactions, for examples refs. 1-4, [1][2][3][4] and enzymatic ones, for examples refs. 5-9, 5-9) have already been developed. Recently, we have developed a new asymmetric synthesis of 1,4-and 1,5-diols from the ene aldehydes involving the intramolecular haloetherification reaction of their C 2 -symmetric acetals as a key step (Eq. 1). 10,11) (1)We then planned to extend this methodology to the symmetric compounds with two prochiral olefins. If the reaction can successfully discriminate the diastereotopic groups and their faces, it will be quite useful for constructing optically active compounds because it can produce chiral non-racemic compounds bearing multichiral centers and the remaining olefin can be used for further transformations (Eq. 2). (For examples of discrimination of prochiral two olefinic groups by halocyclization using chiral auxiliary, see refs 12-18.) [12][13][14][15][16][17][18] (2)Based on this idea, we studied the intramolecular haloetherification reaction of cyclohexa-1,4-dienes 1 having the C 2 -symmetric acetal on the side chain and found that the reaction discriminated the two prochiral olefins in a highly diastereoselective manner to give 2 as the major product (Chart 1).19) The alkoxy group of the mixed acetals was then converted to an alkyl group. The obtained alkylated compounds 3 were subjected to several transformation reactions forming optically active cyclohexane derivatives with multichiral centers. We now present the full details of our study. Results and DiscussionThe optically active monosubstituted cyclohexadiene acetals (1a, b) were synthesized as follows (Chart 2). The cyclohexadiene acetals (4, 5) were prepared from benzoic acid according to a literature procedure. 20) Their transacetalization with (ϩ)-hydrobenzoin 21) gave 1a and 1b in good yields. The disubstituted cyclohexadiene acetals (1c, d) were synthesized from compound 6, which was obtained by reductive alkylation 22) of methyl benzoate followed by reduction with DIBAL-H (Chart 3). Protection of the hydroxy group of 6 by the tert-butyldiphenylsilyl (TBDPS) group and selective deprotection of the resulting disilyl ether afforded 7 in good yield. The Swern oxidation 23) of 7 followed by acetalization with (ϩ)-hydrobenzoin produced the optically active 3,3-disubstituted cyclohexadiene acetal silyl ether 1c. The desilyla- A novel asymmetric synthesis of the cyclohexane derivative functionalized by some substituents has been developed from the diene acetals (1), prepared from the corresponding diene aldehyde and (؉)-hydrobenzoin. The treatment of 1 with NBS in the presence of MeOCH 2 CH 2 OH predominantly afforded 2 in a stereoselective manner. Subsequent alkylation of the methoxyethoxy group produced the optically active cyclohexene compounds (3) in good yields. The stereoselective ch...

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Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis by the Intramolecular Haloetherification Reaction of Ene Acetal: Discrimination of Prochiral Dienes in Cyclohexane Systems

Fujioka

Kotoku

Sawama

et al. 2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…Evaporation of the alcohol fractions and the alkaline treatment gave optically pure (S)-82-OH (ee > 99%) in a yield of 73%. It is well known that the enantioselectivity is varied with the factors such as substrate (5)(6)(7)(8)(22)(23)(24), solvent (22,(25)(26)(27) and the reaction temperature (27) for lipase catalyzed transesterification. In the previous papers (28-30), we reported that the enantioselectivity was affected by a combination of substrate and solvent structures, nature of the solvent and the reaction temperature for PCL catalyzed transesterification between tributyrylglycerol (TB) and secondary alcohol in organic solvent.…”

Section: Resolution Of Optically Pure 2-octanol In a Preparative Scmentioning

confidence: 99%

“…in organic solvent (1)(2)(3)(4)(5)(6)(7)(8): IPA and VA irreversibly react with the active serine residue in lipase to give the acetyl-enzyme intermediate [Enz-Ac] because isopropenyl and vinyl alcohols are immediately converted to acetone and acetaldehyde by keto-enol tautomerization and this irreversibility serves to acceleration in the reaction rate (1,7). Such reactions are called "irreversible transesterification" and used for kinetic resolution of various secondary alcohols (2)(3)(4)(5)(6)(7)(8).…”

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Kinetic Resolution of Enantiomers in Racemic and Enantiomerically Enriched 2-Alkanols by <i>Pseudomonas cepacia</i> Lipase Catalyzed Transesterification with Isopropenyl Acetate in Organic Solvent

et al. 2005

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“…[1][2][3][4][5][6] In recent years, biocatalytic methodology, once thought to be an esoteric area and largely confined to the laboratories with necessary expertise, has now become a primary activity of research in most of the leading research laboratories working in the areas of both organic, bioorganic and medicinal chemistry. [7][8][9][10][11][12][13][14] Despite the very useful and attractive applications of chemico-enzymatic methodology in synthetic organic chemistry, there still exists some apprehension amongst organic chemists with respect to handling of the enzymes and experimental techniques. Also most of the commercially available enzymes are expensive.…”

Section: Introductionmentioning

confidence: 99%

Applications of liver acetone powders in enantioselective synthesis

Basavaiah¹

2001

Arkivoc

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Applications of liver acetone powders (crude enzymes) as possible substitutes for purified enzyme preparations, hydrolases, in enantioselective organic transformations have been systematically investigated. (1R, 2R)-2-(4-Alkylphenoxy)cyclohexan-1-ols, (1R, 2R)-& (1S, 2S)-2-nitroxycyclohexan-1-ols, (1R, 2S)-2-arylcyclohexan-1-ols, (3R, 4R)-6-methyl-3-phenylhept-1-en-4-ol, and (R)-1-(naphth-1-yl)ethanol have been synthesized in enantiomerically pure form via the enantioselective hydrolysis of the corresponding racemic acetates mediated by liver acetone powders.

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The biocatalytic approach to the preparation of enantiomerically pure chiral building blocks

Cited by 525 publications

References 0 publications

Asymmetric Synthesis by the Intramolecular Haloetherification Reaction of Ene Acetal: Discrimination of Prochiral Dienes in Cyclohexane Systems

Asymmetric Synthesis by the Intramolecular Haloetherification Reaction of Ene Acetal: Discrimination of Prochiral Dienes in Cyclohexane Systems

Kinetic Resolution of Enantiomers in Racemic and Enantiomerically Enriched 2-Alkanols by <i>Pseudomonas cepacia</i> Lipase Catalyzed Transesterification with Isopropenyl Acetate in Organic Solvent

Applications of liver acetone powders in enantioselective synthesis

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