A practical and efficient synthesis of new class of isoxazoli­dinyl epoxides by direct treatment of 4,5-unsubstituted 2,3-dihydroisoxazoles with Oxone and NaHCO3 in acetone/water solution is described. All epoxidation reactions proceed with excellent anti-selectivity and provide stable products in very good yields. A concept for the development of stereoselective approach to 3,4-trans-hydroxy-substituted isoxazolidines, namely triazole derivatives as important molecules in medicinal chemistry is presented. The synthesis is characterized by highly syn-stereoselective conversion of epoxides to anomeric bromoisoxazolidines, which are found to be powerful reaction intermediates for the coupling reactions with various nucleophiles.

Styrene monooxygenases are a group of highly selective enzymes able to catalyse the epoxidation of alkenes to corresponding chiral epoxides in excellent enantiopurity. Chiral compounds containing oxirane ring or products of their hydrolysis represent key building blocks and precursors in organic synthesis in the pharmaceutical industry, and many of them are produced on an industrial scale. Two-component recombinant styrene monooxygenase (SMO) from Marinobacterium litorale was expressed as a fused protein (StyAL2StyB) in Escherichia coli BL21(DE3). By high cell density fermentation, 35 gDCW/L of biomass with overexpressed SMO was produced. SMO exhibited excellent stability, broad substrate specificity, and enantioselectivity, as it remained active for months and converted a group of alkenes to corresponding chiral epoxides in high enantiomeric excess (˃95–99% ee). Optically pure (S)-4-chlorostyrene oxide, (S)-allylbenzene oxide, (2R,5R)-1,2:5,6-diepoxyhexane, 2-(3-bromopropyl)oxirane, and (S)-4-(oxiran-2-yl)butan-1-ol were prepared by whole-cell SMO.

A synthetic approach towards new 1,2,3‐triazoles bearing the 3‐hydroxymethylated 4‐hydroxyisoxazolidine moiety has been described. The strategy has relied on dihydroxylation and epoxidation reactions of 4,5‐unsubstituted 2,3‐dihydroisoxazoles, allowing the introduction of the hydroxy group at the isoxazolidine ring in a trans stereoselective manner with respect to the substituent at C‐3 carbon atom. The requisite 5‐azidoisoxazolidines have been prepared from activated isoxazolidines possessing a good leaving group at C‐5 carbon atom by treatment with trimethylsilyl azide and Lewis acid (isoxazolidinyl benzoates) or with sodium azide (chloroisoxazolidines). The 1,2,3‐triazole moiety has been synthesized through copper(I)‐catalyzed azide‐alkyne cycloaddition.

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