Sulfoxides, «,3-epoxy preparation

Sharpless and Masumune have applied the AE reaction on chiral allylic alcohols to prepare all 8 of the L-hexoses. ° AE reaction on allylic alcohol 52 provides the epoxy alcohol 53 in 92% yield and in >95% ee. Base catalyze Payne rearrangement followed by ring opening with phenyl thiolate provides diol 54. Protection of the diol is followed by oxidation of the sulfide to the sulfoxide via m-CPBA, Pummerer rearrangement to give the gm-acetoxy sulfide intermediate and finally reduction using Dibal to yield the desired aldehyde 56. Homer-Emmons olefination followed by reduction sets up the second substrate for the AE reaction. The AE reaction on optically active 57 is reagent... 

Optically pure (S)-benzyl methyl sulfoxide 139 can be converted to the corresponding a-lithio-derivative, which upon reaction with acetone gave a diastereomeric mixture (15 1) of the /S-hydroxysulfoxide 140. This addition reaction gave preferentially the product in which the configuration of the original carbanion is maintained. By this reaction, an optically active epoxy compound 142 was prepared from the cyclohexanone adduct 141181. Johnson and Schroeck188,189 succeeded in obtaining optically active styrene oxide by recrystallization of the condensation product of (+ )-(S)-n-butyl methyl sulfoxide 143 with benzaldehyde. 

The first synthesis of d4T was accomplished in 1966 by Horwitz from l-(2-deoxy-3,5-epoxy-/3-D-r/2reo-pentosyl)thymine abstraction of a proton from the 2 -position by potassium butoxide in DMSO resulted in an opening of the oxetane ring and formation of d4T. Other syntheses were based on the elimination of sulfoxide or the selenoxide moiety placed at the C-2 position in the nucleoside, which was prepared from cheap lactone 6 (O Scheme 7) [6]. 

These trihydroxy sulfoxides are useful molecules in total synthesis because of the possible transformation of the sulfoxide into aldehyde by a Pummerer rearrangement. Homoallylic 3-hydroxy sulfoxides have also been prepared from 3-epoxy sulfoxides, readily obtained from methyl monochloroacetate (Scheme 61a). ... 

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