Microbial oxygenation of cycloheptyl-N-phenylcarbamate and (±)-trans-2-fluorocycloheptyl-N-phenylcarbamate with beauveria bassiana

Pietz, Sylke; Fröhlich, Roland; Haufe, Günter

doi:10.1016/s0040-4020(97)10147-8

Cited by 19 publications

(13 citation statements)

References 54 publications

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“…[9] This result is in agreement with the literature because many other examples of moderate stereoselectivity have been reported [4,15] for the hydroxylating microorganism Beauveria bassiana. However, despite this general trend, a few highly selective biohydroxylations (80Ϫ90% optical purities) have also been observed [7,16,17] for this fungus. This encouraged us to attempt to improve the selectivity of the hydroxylation under consideration.…”

Section: Introductionmentioning

confidence: 87%

Chiral Auxiliaries as Docking/Protecting Groups in Biohydroxylation: The Hydroxylation of Enantiopure Spirooxazolidines Derived from Cyclopentanone UsingBeauveria bassiana ATCC 7159

Raadt¹,

Fetz²,

Griengl³

et al. 2000

Eur. J. Org. Chem.

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The aim of this work was to explore the scope and limitations of chiral docking/protecting groups as chiral auxiliaries in the biohydroxylation of unactivated methylene groups. As a model compound, cyclopentanone 1 was reacted with a range of enantiomerically pure amino alcohols 2a−n as well as 7a and b, varying substituents R 1 and R 2 . The resulting chiral spirooxazolidines 3a−n as well as 8a and b were exposed to the fungus Beauveria bassiana ATCC 7159 and the resultant hydroxylated products were characterised. Introducing chirality into the substrate before the fermentation was found to have a major effect on the course of the biohydroxylation relative to the achiral analogue 3a (Table 1, entry 1). The nature of R 1 /R 2 influenced both the product yield and

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Section: Introductionmentioning

confidence: 87%

Chiral Auxiliaries as Docking/Protecting Groups in Biohydroxylation: The Hydroxylation of Enantiopure Spirooxazolidines Derived from Cyclopentanone UsingBeauveria bassiana ATCC 7159

Raadt¹,

Fetz²,

Griengl³

et al. 2000

Eur. J. Org. Chem.

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“…Relative amounts and absolute configurations of the products are given in Table 2 together with the ratios, yields, and enantiomeric excesses of the products isolated in our earlier study. 7 In contrast to the transformation of the six-membered compounds 3, no products hydroxylated both in an alicyclic and aromatic position were found in the product mixtures of the transformation of 6 under the same conditions.…”

Section: Resultsmentioning

confidence: 91%

“…The products, isolated yields, and enantiomeric excesses of biotransformation of racemic trans-2-fluorocycloheptyl N-phenylcarbamate (()-6 have already been reported (Scheme 3). 7 Two trans-4-hydroxylated compounds (with regard to the haptophoric carbamate function), (-)-15 (24% yield, 82% ee) and (+)-17 (4.5% yield, 79% ee), were isolated. One of those was a 1,4-fluorohydrin, while the other was a 1,3-fluorohydrin, but both of them were hydroxylated in a formal 4-position in relation to the anchoring group.…”

Section: Resultsmentioning

confidence: 99%

“…For the products of transformation of the nonfluorinated seven-membered ring carbamate a 92:8 ratio of trans to cis 4-hydroxylated compounds was found, considering that the ketone isolated in 12% yield was formed exclusively from trans-4-hydroxycycloheptyl N-phenylcarbamate. 7 From (R,R)-(-)-6, the trans-5-hydroxy derivative 15 was formed with a 84:16 selectivity over the cis isomer 16 and the trans-4-hydroxy derivative 17 was formed with a 16:84 selectivity compared to the cis isomer 18. The reverse diastereoselectivity was observed for (S,S)-(+)-6.…”

Section: Resultsmentioning

confidence: 99%

“…The fungus Beauveria bassiana is one of the most frequently used microorganisms for this purpose, and its biocatalytic reactions have been recently reviewed . This fungus is known to hydroxylate, in addition to amides 4-6 and carbamates, − saturated N-containing heterocycles. 4a, Even saturated hydrocarbon positions of cycloalkanes, saturated steroids or terpenes, and side chains of aromatic hydrocarbons not having any electron-rich functional binding group may be hydroxylated 5b. Moreover, it is well-known that this fungus can also p -hydroxylate aromatic rings of N -benzoylamines, N -phenylcarbamates, or substituted heteroaromatics .…”

Section: Introductionmentioning

confidence: 99%

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Selectivity of Biohydroxylation with Beauveria bassiana of trans-2-Fluorocycloalkyl N-Phenylcarbamates

2002

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Biohydroxylation with Beauveria bassiana of racemates and the pure enantiomers of trans-2-fluorocyclohexyl- 3 and trans-2-fluorocycloheptyl N-phenylcarbamates 6 were investigated and compared with results found for the corresponding nonfluorinated parent compounds. In all cases, mixtures of diastereomeric products hydroxylated in the 4-position were isolated, besides products of p-hydroxylation of the aromatic ring and succeeding compounds derived from these primary reaction products. The regioselectivity of hydroxylation by this fungus is not changed by a single fluorine substituent attached closely to the electron-rich anchoring group in the trans-2-position. There is a different influence on the diastereoselectivity of hydroxylation depending on the absolute configuration of the fluorinated substrates. While the transformation of the (S,S)-2-fluorocycloalkyl N-phenylcarbamates is not diastereoselective giving almost 1:1 mixtures of cis- and trans-4-hydroxyl compounds, the corresponding reactions of the (R,R)-isomers led preferentially to the products trans-hydroxylated in the 4-position. The transformation of the racemic fluorinated six-membered N-phenylcarbamate 3 led to products having a very small enantiomeric excess. The fluorine substituent slightly increased the enantioselectivity of transformation of the racemic seven-membered substrate 6 compared to the C(s)()-symmetric nonfluorinated carbamate. Thus, the fluorine substituent in the trans-2-position in these examples did not change the regioselectivity but rather influenced the stereochemistry of biotransformation, depending on the absolute configuration of the substrate and ring size.

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Enantiodivergent Reactions: Divergent Reactions on a Racemic Mixture and Parallel Kinetic Resolution

Russell

Vedejs

2014

Separation of Enantiomers

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Microbial oxygenation of cycloheptyl-N-phenylcarbamate and (±)-trans-2-fluorocycloheptyl-N-phenylcarbamate with beauveria bassiana

Cited by 19 publications

References 54 publications

Chiral Auxiliaries as Docking/Protecting Groups in Biohydroxylation: The Hydroxylation of Enantiopure Spirooxazolidines Derived from Cyclopentanone UsingBeauveria bassiana ATCC 7159

Chiral Auxiliaries as Docking/Protecting Groups in Biohydroxylation: The Hydroxylation of Enantiopure Spirooxazolidines Derived from Cyclopentanone UsingBeauveria bassiana ATCC 7159

Selectivity of Biohydroxylation with Beauveria bassiana of trans-2-Fluorocycloalkyl N-Phenylcarbamates

Enantiodivergent Reactions: Divergent Reactions on a Racemic Mixture and Parallel Kinetic Resolution

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