Wittig rearrangement 2,3 -, chiral induction

Asymmetric Wittig rearrangements.7 High 1,2-asymmetric induction obtains in the [2,3]Wittig rearrangement of the chiral dioxolanes 1 and 3. In each case the... 

Scheme 6.11. Asymmetric induction and chirality transfer in [2,3]-Wittig rearrangements of allylic benzyl [78], ally [78], and trimethylsilylpropargyl [79] ethers.

Hydroxy-amides. - Wittig rearrangement of acetamide (424) [LDA, -85 C] provides almost exclusively the erythro-a-hydroxy-amide (425). The likely transition-state geometry suggests that the presence of vinylic substituents larger than methyl should at least maintain this level of selectivity during rearrangement. Unfortunately similar reactions of chiral amides derived from prolinol result in only moderate asymmetric induction. 

A study of chiral induction in the asymmetric [2,3]-Wittig rearrangement of allyl benzyl ether in the presence of a bis(oxazoline) chiral ligand [(5,5)-Box-r-Bu] has been reported (Scheme 45). °... 

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