Dithioacetals disulfones

Hough and Richardson58 explored the reaction of unacetylated hexose dithioacetals with peroxypropanoic acid the sulfone 15 initially formed is only marginally stable, and undergoes dehydration to mixtures of the unsaturated disulfone (18) and the 2,6-anhydro-l-deoxy-l,l-bis(ethylsulfo-nyl)alditol (19). All three products are degraded by aqueous ammonia to the next lower sugar (16) and bis(ethylsulfonyl)methane (17). This degradation is much slower for 18 than for 15, and it was concluded that hydration of 18 to 15 precedes disproportionation (Scheme 8). 

The diethyl (LXXXVI) and ethylene (XC) dithioacetals of scyllo-inosose are known,208 and they have been oxidized to the corresponding disulfones LXXXYII and XCI.208 209 Treatment of the disulfone LXXXVII with am-... 

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-... 

A novel method for the synthesis of alkenes is based on the coupling of aldehydes with dithioacetals to give the corresponding hydroxy thioacetals, which afford vicinal disulfides via reductive phenylthio migration.242 The syn-diastereomers are the major products from symmetrical compounds while the anti-isomers are obtained with high selectivity with unsymmetrical compounds. Separation of the diastereomers, oxidation to the 1,2-disulfones, and reductive elimination give the corresponding alkenes with moderate stereoselectivities (Eq. 137).242... 

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). 

This reaction was first reported by MacDonald and Fischer in 1952. It is the degradation of hexoses into pentoses involving the steps of formation of dithioacetal, oxidation to unsaturated disulfone by means of perphthalic acid, hydrazine treatment, and benzalde-hyde splitting of the corresponding hydrazone. Therefore, the whole process is known as the MacDonald-Fischer degradation. In addition, when the unsaturated disulfone is dissolved in aqueous ammonia or methanol saturated with ammonia, 2-deoxy-2-amino sugar is resolved. This reaction in combination with mass spectroscopy was used to study the structure and stereochemistry of carbohydrates. ... 

An important degradation reaction of aldoses proceeds via the disulfone of the dithioacetal ... 

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