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چکیده
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Enantiopure epoxides are important and versatile intermediates for the syntheses of pharmaceuticals, fine chemicals and biologically active compounds [1]. Styrene oxides are particularly useful as they present in building blocks of pharmaceutically important compounds such as the antidepressant Sertraline and the adrenergic blockers Nifenalol and Salmeterol [2]. Consequently, in the last 30 years, a variety of direct epoxidation and resolution methods for the synthesis of enantiopure oxiranes have been successfully developed. More convenient and efficient routes to prepare optically pure styrene oxides involve the initial enzymatic or chemical asymmetric reduction of -halogenated acetophenones [3]. Biocatalysis has always been a key focus area in biotechnology and new approaches for the utilization of biocatalysts have continued to emerge over the past year. It has been reported that reduction of ketones may be performed using various plant biocatalysts in different forms: as suspension cell cultures, cell and organ cultures, immobilised plant cells; and also as cuted fresh fruits and vegetables [4]. We report here a simple procedure under mild and green condition for the preparation of enantiopure styrene oxides from simple -halo ketones (Scheme 1), which combines the use of plants as biocatalyst and SN2 closure of the epoxide ring. Structure of products have been identified by NMR spectroscopy and enantiomeric excess determined by polarimeter and HPLC.
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