Sugars ethylene acetal deriv

The formation and chemistry of dithioacetals of sugars have been reviewed. 4,6-Dichloro-4,6-dideoxy-D-gaIactose reacted with cyclohexanone ethylene acetal in the presence of an acid catalyst to give the acyclic derivative (48), which was converted into the corresponding 5-ulose. Treatment with base converted (48) into the 5,6-anhydro-derivative, which was hydrolysed to give the L-idose diacetal (49), presumably by way of a4,5-anhydro-D-glucose derivative. 

Some of the ester derivatives of polysaccharides, such as cellulose acetates or nitrates, are of considerable industrial importance (Chapter XII). Those of the sugars have not been commercialized to any great extent, with the possible exception of sucrose octaacetate. An important series of surface-active materials are provided by alditols and their anhydro derivatives partially esterified with long-chain fatty acids (Chapter VII). For the latter derivatives, increased solubility in water is provided by reaction with ethylene oxide. 

Corey and Hase have found that 1,3-dithiolans and 1,3-dithians can be converted in good yields into dimethyl acetals, cyclic acetals, or thioacetals (or thioketals) upon reaction of the mono-5-methylated derivatives with methanol, ethylene glycol, and mercaptoethanol, respectively. These interchanges do not appear to involve the free carbonyl compound. The disulphonium salt prepared by the reaction of triethyloxonium tetrafluoroborate with 2-phenyl-l,3-dithiolan can be used to prepare benzylidene derivatives of 1,2-, 1,3-, and 1,4-diols (30— 80%) under basic conditions. This reaction appears to have considerable potential as a route to benzylidenated sugars. 

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