Dithioacetals, reaction with sulfonyl

Other studies of selective sulfonylation at a primary hydroxyl group of sugars were made with 5-deoxy-l,2-0-isopropylidene-a-D-xy/o-hexofuranose at —12° to give the 6-p-toluenesulfonate and 6-methanesulfonate. On wanning the reaction mixture to 25°, these derivatives were converted into 3,6-anhydro-5-deoxy-l,2-0-isopropyl-idene-a-D-xyio-hexofuranose. The formation of 2,5-anhydrides on p-toluenesulfonylation of dialkyl dithioacetals of pentoses probably proceeds similarly, through the 5-p-toluenesulfonates. 

MacDonald and H. O. L. Fischer372 oxidized D-glucose diethyl dithioacetal pentaacetate (24) and its D-manno isomer with mono-peroxyphthalic acid in ether, isolating not the epimeric disulfones but a common product, to which they assigned the structure 3,4,5,6-tetra- O - acetyl -1,2- dideoxy-1,1 -bis (ethylsulfonyl)-D-arabtno-hex-1-enitol (176). Ammonolysis of 176 and reacetylation afforded 177, which was also prepared by oxidation of 2-acetamido-3,4,5,6-tetra-0-acetyl-2-deoxy-D-glucose diethyl dithioacetal, whereas the action of hydrazine in methanol on 176 produced a retroaldol reaction (and saponification) affording D-arabinose (179, 40% yield) and bis(ethyl-sulfonyl)methane (178). The latter reaction accords with earlier ob-... 

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