Diastereoselective Synthesis of ‐Hydroxy Sulfoxides: Enzymatic and Biomimetic Approaches

Abstract

Stereoselectivities of up to 98 % have been found in the enzymatic synthesis of β‐hydroxy sulfoxides catalyzed by cyclohexanone monooxygenase (CHMO). The diastereoselectivity of the “one‐pot” preparation of the title compounds in the presence of bovine serum albumin has also been investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Recent Developments in Flavin‐Based Catalysis

“…Chiral β-hydroxy sulfoxides represent interesting compounds used as chiral auxiliaries in asymmetric synthesis, asymmetric ligands, or as building blocks for the synthesis of cyclic sulfides, benzoxathiepines, allylic alcohols, or leukotrienes [27]. The sulfoxidation of these substrates is a kinetic resolution, in which both the sulfide and the sulfoxide can be obtained in chiral form.…”

Albumin as a promiscuous biocatalyst in organic synthesis

“…77 Later on, racemic b-hydroxysuldes were studied by a biomimetic approach based on a one-pot in situ thiolysis of epoxides followed by BSA/tBuOOH oxidation. 78 Moderate-to- Fig. 2 Proposed mechanism for the enamine-mediated addition of acetone to 6-methoxy-2-naphthaldehyde promoted by albumin.…”

“…77 Later on, racemic b-hydroxysuldes were studied by a biomimetic approach based on a one-pot in situ thiolysis of epoxides followed by BSA/tBuOOH oxidation. 78 Moderate-to- In addition, the same approach has been investigated by using styrene oxide as an example of an a-substituted 1,2-epoxide (Scheme 22). Nucleophilic attack of thiophenol occurred preferentially at the benzylic position and the subsequent oxidation proceeded with good diastereoselectivity for the major regioisomers, but again with no appreciable enantioselectivity.…”

Recent Developments in the Application of Baeyer–Villiger Monooxygenases as Biocatalysts

“…Chiral β‐hydroxysulfoxides are of special interest as chiral auxiliaries and as building blocks for the synthesis of compounds such as benzoxathiepines, allylic alcohols, or macrolides. Recently, a biocatalyzed procedure for the synthesis of these compounds has been described by oxidizing the corresponding β‐hydroxysulfides by using isolated CHMO Acineto 67. Sulfoxidation of trans ‐2‐(phenylsulfinyl)cyclohexan‐1‐ol occurred with excellent regio‐ and enantioselectivity for the preparation of the (1 S ,2 S )‐β‐hydroxysulfoxide.…”