Asymmetric bicyclo-octane esters

The rearrangement of isopent-3-enyl epoxy esters with Cp2ZrCl2/AgC104 yields ABO esters (2,7,8-trioxabicyclo[3.2.1]octane Asymmetric Bicyclo-Octane esters), which are base-stable protecting groups for carboxylic acids [57,79,80] (Scheme 8.40). 

C-Silylation of Li-Ester Enolates. Further applications of a-diphenylmethylsilyl carhoxylates have been reported. Gais and co-workers employed a-methyldiphenylsilyl acetate (16), prepared from (—)-8-phenylmenthol acetate (15), by lithiation with LDA and reaction with methyldiphenylchlorosilane, in an asymmetric Peterson reaction with the bicyclo[3.3.0]octan-3-one derivative (17) to yield a 89 11 mixture of the (Z)- and ( )-esters (18) and (19) About 50% of the starting material was recovered in the unoptimized procedure (eq 13). ... 

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