Search

Biohydrolysis of various alpha-methylstyrene oxide derivatives, differently substituted at the aromatic ring, was studied using 10 epoxide hydrolases from various sources. Findings showed that the enantioselectivity of these biohydrolyses strongly depends on the nature of the enzyme and of the substituent. Using some of these enzymes, this strategy permitted the preparation of these epoxides in high optical purity. The capability to perform efficient preparative-scale resolution using such a biocatalyst was demonstrated by the four-step synthesis of (S)-ibuprofen.

Research was conducted to examine the rate of biohydrolysis and the regioselectivity of several styrene oxide derivatives. These oxides were catalyzed by an epoxide hydrolase activity located in the soluble cell extract of the 'Syncephalastrum racemosum' fungus. Results show that the electronic character of the para substituent affects regioselectivity to and from the terminal and the benzylic carbon atom.

INTRODUCTION Enantiopure epoxides (often incorrectly called 'chiral' epoxides) are valuable intermediates in organic synthesis. Their corresponding vicinal diols, which can be either transformed into the epoxide itself or used as [...]

An approach for the asymmetric synthesis of enantiopure para-substituted styrene oxides is discussed. The method utilizes two fungi Aspergillus niger and Beauveria sulfurescens as reaction catalysts. The microorganisms perform biotransformation of the para-substituted styrene oxide derivatives via production of epoxide hydrolases which afford the reaction with high enantioselectivity.

rac-1 is enantioselectively hydrolyzed by two fungi, Aspergillus niger and Beauveria sulfurescens. Styrene oxide enantiomers show opposite enantioselectivity depending on the two fungi. A high level of enantiomeric purity is observed in the (S) enantiomer and the (R) antipode of styrene epoxide. Either enantiomers can be generated in adequate quantities due to microbiological conversions in large amounts. The total structure of the product diol is not opposite, despite the opposite enantioselectivity toward the epoxide, due to the occurrence of the (R) enantiomer in both cases.

Enantioselective or diastereoselective hydrolysis of epoxide mixtures is seen in a total cell microbiological method. The utility of this method is analyzed. Epoxides with high enantiomeric purity are synthesized in a multigram preparative-scale method. Anaerobic conditions improve the process. The fungus, Aspergillus niger, is used in selective hydrolyses, and is possibly controlled by an intracellular EH enzyme, revealing high enantioselectivity or diastereoselectivity, and ideal regio- and stereoselectivity during the interaction.

Conflicting optical rotation signs, and thus opposite absolute configurations for alpha-methylstyrene oxide (1), have been found in various publications. Thus, researchers should be more careful in determining the absolute configuration attributions. A study which investigated such conflicting configurations on 1 led to the interesting observation that the biocatalyzed hydrolysis of 1, employing either Agrobacterium niger or A. radiobacter epoxide hydrolases, were enantiocomplementary. This permitted the preparation of both enantiomers of 1 by simply selecting the proper biocatalyst.