Prochiral diol, stereoselective oxidation

Chiral Alcohols and Lactones. HLAT) has been widely used for stereoselective oxidations of a variety of prochiral diols to lactones on a preparative scale. In most cases pro-(3) hydroxyl is oxidized irrespective of the substituents. The method is apphcable among others to tit-1,2-bis(hydroxymethyl) derivatives of cyclopropane, cyclobutane, cyclohexane, and cyclohexene. Resulting y-lactones are isolated in 68—90% yields and of 100% (164,165). 

Isolated enzymes can also be used to catalyse selective oxidation reactions. For, example, galactose oxidase oxidizes xylitol into (L)-xylose (Scheme 4.15), while HLAD catalyses the stereoselective oxidation of prochiral diols of the type (12) to give, initially, a chiral hydroxyaldehyde... 

Efficient synthetic approaches to the optically active spiro-sulfuranes and their oxides have been reported by Martin and Drabowicz [65]. The preparation of optically active spirosulfuranes 45 and 46 was performed by asymmetric dehydration of the corresponding prochiral sulfoxide diols 47, as shown in Scheme 29. The optically active oxides 48 and 49 were prepared by oxidation of 45 and 46 with m-chloroperbenzoic acid (mCPBA). The synthesis of the optically active oxides was conducted by the stereoselective conversion of the chiral sulfuranes using Ru04, according to the procedure reported earlier [66]. 

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