Diethyl dithioacetal, oxidation preparation

Whereas ethyl l-thio-d-D-arabinofuranoside cannot be prepared directly, the 5-O-benzoyl diethyl dithioacetal gave 38% of ethyl 5-O-benzoyl-l-thio-0-D-arabinofuranoside, which was debenzoylated to the desired product. The 5-benzoate of ethyl 1-thio-a-D-ribofuranoside was similarly prepared.88 Two other compounds, ethyl 2-acetamido-2-deoxy-l-thio-/3-L-arabino-furanoside72 and ethyl 2-acetamido-2-deoxy-l-thio-a-D-xylofuranoside,73 were prepared from the corresponding d-galacto and d-gluco analogs by periodate oxidation, and subsequent borohydride reduction of the product. 

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-... 

Finally MacDonald and Fischer have prepared the free ajyZo-pento-dialdose (8) by the sulfone-degradation method. The diethyl dithioacetal of scyllo-inosose (12) was oxidized to the corresponding disulfone which, on treatment with ammonia, gave the dialdose (8). The structure was proved by converting the compound into the bis(ethylene dithioacetal) derivative, which was identical with that obtained from a /io-pentodialdose prepared by a previous method. ... 

Under such conditions secondary alcohols rarely afford homogeneous products, as the aldehydes expected as primary products too readily undergo further reactions. Exceptionally, a preparatively useful application has been found in the degradation of aldose diethyl dithioacetals these are oxidized by organic peracids or by hydrogen peroxide in the presence of ammonium molybdate to the disulfones which are cleaved at secondary alcohol groups by dilute ammonia solution.78,79 This method has been applied to acetyl-... 

D-Arabinose 88 l-Deoxy-l,l-bis(ethylsulfonyl)-D-mannitol (1 g) (prepared by oxidation of D-mannose diethyl dithioacetal with peroxypropionic acid in dioxan) is made into a slurry with water (10 ml), and then concentrated aqueous ammonia solution (1 drop) is added. The sulfone dissolves rapidly and after 30 min the precipitated diethyl methylene disulfone is filtered off. The filtrate is extracted four times with chloroform (10-ml portions), and the aqueous phase is evaporated in a vacuum at 40°. The residue is treated with hot methanol (5 ml) and after being kept for 24 h at 4° affords / -D-arabinose (0.32 g, 86%), [a]D20 —102° (c 3.5 at equilibrium in water). 

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