Sulfite esters asymmetric dihydroxylation

The diols (97) from asymmetric dihydroxylation are easily converted to cyclic sulfite esters (98) and thence to cyclic sulfate esters (99). ° This two-step process, reaction of the diol (97) with thionyl chloride followed by ruthenium tetroxide catalyzed oxidation, can be done in one pot if desired and transforms the relatively unreactive diol into an epoxide mimic, i.e. the 1,2-cyclic sulfate (99), which is an excellent electrophile. A survey of reactions shows that cyclic sulfates can be opened by hydride, azide, fluoride, thiocyanide, carboxylate and nitrate ions. ° Benzylmagnesium chloride and the anion of dimethyl malonate can also be used to open the cyclic sulfates.Opening by a nucleophile leads to formation of an intermediate P-sulfate anion (100) which is easily hydrolyzed to a p-hydroxy compound (101). ° Conditions for catalytic acid hydrolysis have been developed that allow for selective removal of the sulfate ester in the presence of other acid sensitive groups such as acetals, ketals and silyl ethers. ... 

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