Eine chiral ökonomische Totalsynthese von (<i>R</i>)‐ und (<i>S</i>)‐Muskon via Epoxysulfoncyclofragmentierung

Branca, Quirico; Fischli, Albert

doi:10.1002/hlca.19770600323

Cited by 83 publications

(16 citation statements)

References 28 publications

(21 reference statements)

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“…The latter is a popular chiral building block for the synthesis of vitamins (e.g., a-tocopherol [6] ), fragrance components (e.g., muscone [7] ), and antibiotics (e.g., calcimycin, [8] palinurin, [9] rapamycin, [10] 13-deoxytedanolide, [11] dictyostatin [12] ) and natural products (e.g., spiculoic acid A [13] ). Classical methods for its preparation include the diastereoselective addition of non-racemic alcohols as chiral auxiliaries, [14] the transformation of a chiral homoallylic acetate [15] or involve aldol condensation [16] and -most prominent -the transition metal-catalysed asymmetric hydrogenation of acrylate esters using Rh [17] (ee up to 99%) or Ru [18] (ee up to 94%).…”

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confidence: 99%

Asymmetric Synthesis of (R)‐3‐Hydroxy‐2‐methylpropanoate (‘Roche Ester’) and Derivatives via Biocatalytic CC‐Bond Reduction

et al. 2010

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Enoate reductases from the old yellow enzyme family were employed for the asymmetric bioreduction of methyl 2-hydroxymethylacrylate and its O-allyl, O-benzyl and O-TBDMS derivatives to furnish (R)-configurated methyl 3-hydroxy-2-methylpropionate products in up to > 99% ee Variation of the O-protective group had little influence on the stereoselectivity, but a major impact on the reaction rate.Keywords: biocatalysis; C=C-bioreduction; enoate reductase; old yellow enzyme; substrate engineeringThe asymmetric reduction of C=C bonds creates (up to) two chiral carbon centres and is thus one of the most widely employed strategies for the production of chiral materials. The biocatalytic variant, which is applicable to activated alkenes bearing an electron-withdrawing substituent is catalysed by enoate reductases [EC 1.3.1.X], [1,2] which are members of the old yellow enzyme (OYE) family.[3] Over the past few years, increasing attention has been devoted to these flavoproteins [4] in view of their substrate scope, [5] encompassing a,b-unsaturated carbonyl compounds (such as enals and enones), as well as carboxylic acids and derivatives thereof (such as esters, cyclic imides, nitriles, lactones) and nitroalkenes. As a rule of thumb, the degree of activation of the C=C-bond exerted by the electron-withdrawing effect of the activating substituent goes hand in hand with the substrate acceptance, which ensures generally fast reaction rates for enals, enones and nitroalkenes, whereas (di)carboxylic acids and esters are transformed more slowly.To illustrate the importance of this enzyme class for asymmetric synthesis, we aimed at their applicability for an industrially relevant product, that is, (R)-3-hydroxy-2-methylpropanoate, which is commonly denoted as the Roche ester. The latter is a popular chiral building block for the synthesis of vitamins (e.g., a-tocopherol [6] ), fragrance components (e.g., muscone [7] ), and antibiotics (e.g., calcimycin, [8] palinurin, [9] rapamycin, [10] 13-deoxytedanolide, [11] dictyostatin [12] ) and natural products (e.g., spiculoic acid A [13] ). Classical methods for its preparation include the diastereoselective addition of non-racemic alcohols as chiral auxiliaries, [14] the transformation of a chiral homoallylic acetate [15] or involve aldol condensation [16] and -most prominent -the transition metal-catalysed asymmetric hydrogenation of acrylate esters using Rh [17] (ee up to 99%) or Ru [18] (ee up to 94%). For the biocatalytic synthesis of the Roche ester only few examples are reported: the stereoselective oxidation of 2-methyl-1,3-propanediol by Gluconobacter and Acetobacter spp. [19] (ee up to 97%), the asymmetric reduction of ethyl 4,4-dimethoxy-3-methylcrotonate using bakers yeast [20] and the stereoseletive (formal) b-hydroxylation of isobutyric acid using Pseudomonas putida (ATCC 21244).[21] All of these biotransformations were performed using whole (fermenting) microbial cells with several enzymes being involved. Only recently, was it shown that a non-flavin NADH-dependen...

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confidence: 99%

Asymmetric Synthesis of (R)‐3‐Hydroxy‐2‐methylpropanoate (‘Roche Ester’) and Derivatives via Biocatalytic CC‐Bond Reduction

et al. 2010

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“…Conversion 12 of the alcohol 24 to the bromide 25 proceeded smoothly, as did Grignard formation and addition to the epoxide 20 to give 26 . Using this approach, we routinely prepare several hundred milligrams of clean alcohol 26 in a run.…”

Section: Resultsmentioning

confidence: 95%

Synthesis of (−)-astrogorgiadiol

Taber

Raciti

2011

Tetrahedron

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Astrogorgiadiol is a naturally occurring Vitamin D analogue that, in cell culture, downregulates the production of the cytokine osteopontin (OPN). OPN has been implicated in virulent asthma, and OPN knockout mice do not develop osteoporosis. As we have pursued whole animal studies with astrogorgiadiol, we have increased the scale of the synthesis. We report an improved preparation of the A-ring synthon and the scale-up of the diasteromerically pure D-ring/sidechain chiron.

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“…Finally, the search of enzymes for the synthesis of chiral synthons is an actual research field in bioorganic chemistry. Several procedures have already become of practical importance, that is, the preparation of mevalonolactone (94), antibiotics (95,96), pheromones (97), a-tocopherol (98), and muscone (99).…”

Section: Enzymesmentioning

confidence: 99%

Aspects of biotechnological production of food flavors

Schreier

1989

Food Reviews International

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Three principle technologies and their potential application for bioflavor production are discussed: (i) plant tissue and cell culture, (ii) use of microorganisms, and (iii) use of enzymes. Plant cell and tissue cultures have been received by scientists with great enthusiasm; however, we have now to realize that much more must be learned about chemical and genetic regulation of plant secondary metabolism before any commercial production becomes a reality. Fermentations and microbial transformations are already used in flavor production and there is no doubt that these technologies will become more significant factors in the production of flavor chemicals in the future. As to enzymes, technical biocatalysts already play a role in stereoselective production of fine chemicals. Regarding natural flavors, we have to intensify our studies on biochemistry and bioregulation of enzymic activities from both plants and microorganisms. If this is done, the use of enzymes for the production of complete natural flavors will be realized in the future. 289Copyright© 1989 by Marcel Dekker, Inc.

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Eine chiral ökonomische Totalsynthese von (R)‐ und (S)‐Muskon via Epoxysulfoncyclofragmentierung

Cited by 83 publications

References 28 publications

Asymmetric Synthesis of (R)‐3‐Hydroxy‐2‐methylpropanoate (‘Roche Ester’) and Derivatives via Biocatalytic CC‐Bond Reduction

Asymmetric Synthesis of (R)‐3‐Hydroxy‐2‐methylpropanoate (‘Roche Ester’) and Derivatives via Biocatalytic CC‐Bond Reduction

Synthesis of (−)-astrogorgiadiol

Aspects of biotechnological production of food flavors

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