Catalytic ADH

In fact, although good enantioselectivities in ADH of dialkyl substituted olefins could be previously obtained through the use of stoichiometric reagents at low temperature [34], the catalytic ADH developed by Sharpless is by far the best method that the synthetic organic chemist has presently at his hands. l... 

Shatpless and his group have also prepared polymer-bound alkaloid derivatives which allow the use of heterogenous catalytic ADH. TLe reactions proceed in good to excellent enantioselectivities in the case of rrans-stilbene, and the Os04-polymer complex can be used for iterative processes [35]. 

Sharpless and his group have also studied a series of selective transformations of r/jreo-2,3-dihydroxy esters (6) -prepared by catalytic ADH of a,P-unsaturated esters 5- which lead to very useful and highly elaborated synthetic intermediates [36], such as a-(sulfonyloxy)-P-hydroxyesters (2), P-acetoxy-a-bromo esters or a-acetoxy-p-bromo esters (8 and 9), threo- and erythro-glycidxc. esters QO and U.) and P-hydroxy esters (12). The substituent at the p-position plays an important role in determining the regiochemistry of the bromination of the 2,3-dihydroxy esters whereas a P-alkyl substituent leads to p-acetoxy-a-bromo esters, a phenyl group directs formation of the a-acetoxy-P-bromo esters (Scheme 10.5). 

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