Biocatalytic and chemical routes to all the stereoisomers of methionine and ethionine sulfoxides

• Published in: Tetrahedron: asymmetry 1999-07, Vol.10 (15), p.2833-2843
• Main Authors: Holland, Herbert L, Andreana, Peter R, Brown, Frances M
• Format: Article
• Language: English
• ISSN: 0957-4166; 1362-511X
• DOI: 10.1016/S0957-4166(99)00271-2

Biotransformations of the N-phthaloyl derivatives of d- and l-methionine and of d- and l-ethionine by Beauveria bassiana ATCC 7159 or Beauveria caledonica ATCC 64970 produce the corresponding ( S S) sulfoxides in good yield and diastereomeric excess. Pure ( S S S C) diastereomers can be obtained from l-series substrates by crystallisation of the biotransformation extract, and the corresponding ( S S R C) products obtained from d-series substrates by chromatography of the biotransformation extract. Hydrogen peroxide-catalysed oxidation of the N-phthaloyl derivatives of d- and l-methionine and of d- and l-ethionine gives diastereomeric mixtures from which the ( S S S C) and ( R S R C) diastereomers can be obtained by crystallisation, and the ( S S R C) and ( R S S C) diastereomers obtained by chromatography. N-Cbz- and N- t-Boc methionines are also converted to sulfoxides with predominant ( S S) configuration by both B. bassiana and B. caledonica, but the isolated yields and d.e. of products were generally lower than those obtained from the N-phthaloyl substrates. Removal of the N-phthaloyl group from diastereomerically pure methionine and ethionine sulfoxides gave the corresponding amino acid sulfoxides in high yield; removal of N-Cbz and N- t-Boc groups from protected methionine sulfoxides was also achieved without loss of configuration at sulfur.