Rearrangement of derivatives of bis(ethylsulphonyl)-α-d-lyxopyranosylmethane

Bis(ethylsulphonyl)(2,3-O-isopropylidene-a-d-lyxopyranosyl)methane (3) undergoes rearrangement in pyridine or methanolic sodium methoxide to give, at equilibrium, a mixture containing equal amounts of bis (ethylsulphonyl)-(2,3,O-iso-propylidene-a-d-lyxofuranosyl)methane (10), the corresponding ß-furanoid (12), and 3 itself. The rearrangement is completely suppressed by C-methylation of the bis(ethylsulphonyl) moiety. The mechanism of the MacDonald-Fischer degradation of bis (ethylsulphonyl) derivatives of sugars is discussed in the light of these observations. © 1987.