Microencapsulated Chloroperoxidase as a Recyclable Catalyst for the Enantioselective Oxidation of Sulfides with Hydrogen Peroxide

Abstract

Chloroperoxidase can be microencapsulated in silica gel grown around the enzyme by sol-gel techniques. These materials can be usefully employed as catalysts for the asymmetric sulfoxidation of alky aryl sulfides with hydrogen peroxide, with high yields and ee's > 99%. The catalyst an be recycled up to three times without loss of activity and enantioselectivity

7.28 Oxidation of Sulfur, Selenium, and Tellurium

“…446 Microencapsulated CPO into a solid matrix has been developed for biocatalyst recycling. 447 Nicotinamide adenine dinucleotide phosphate-dependent cyclohexanone monooxygenase (CMO) is another useful system for the oxidation of alkyl aryl, dialkyl sulfides, and 1,3-dithiane or 1,3-dithiolane (equation 31, Scheme 68). 448b Active site-directed mutagenesis or random mutagenesis is applicable to improve the activity and stereoselectivity of these enzymes.…”

Recyclable Stereoselective Catalysts

“…Therefore, Strukul et al immobilized chloroperoxidase (CPO) in a microporous silica gel cage to prevent leaching events and catalyst deactivation with hydrogen peroxide (Scheme 1.24 ). Two distinct samples were prepared [173] . Sample A has 3.7 CPO units per 0.3 g of catalyst and gave lower enantioselectivity (73% − 92% ee) than sample B, which has 123 CPO units per 0.3 g ( > 99% ee) (Scheme 1.24 ).…”

Enzymatic synthesis of (R)-modafinil by chloroperoxidase-catalyzed enantioselective sulfoxidation of 2-(diphenylmethylthio) acetamide

“…In this work, an enantioselective synthesis protocol was presented by chloroperoxidase (CPO) catalyzed sulfoxidation of 2-(diphenylmethylthio) acetamide. CPO [13][14][15][16], especially, the epoxidation and sulfoxidation catalyzed by CPO cause great interests [17,18]. However, the actual technical application of CPO was limited because CPO is a highly hydrophilic enzyme, but the poor solubility of organic substrates in aqueous solution prohibits the yield.…”