A Highly Efficient and Stereocontrolled Synthesis of 2‐Deoxy‐1,5‐thioanhydro‐ L ‐hexitols from D ‐Glycals in a Tandem Nucleophilic Displacement Reaction

2‐Deoxy‐1,5‐thioanhydro‐ L ‐hexitols have been synthesized in a concise sequence that includes: i) ring opening of glycals with aqueous mercury( II ) acetate/sodium borohydride; ii) mesylation of the free hydroxy groups of the multifunctionalized open intermediates; and iii) S‐heterocyclization by treatment with sodium sulfide. The thiosugar derivatives are obtained with a 60–80 % yield. Thus, D ‐glucal and D ‐galactal can be converted into the corresponding 2‐deoxy‐1,5‐thioanhydro‐ L ‐hexitols, while L ‐rhamnal gives 3,4‐di‐ O ‐benzyl‐2,6‐dideoxy‐1,5‐thioanhydro‐ D ‐ xylo ‐hexitol. This straightforward chemistry is shown to be useful for the synthesis of glycosyl derivatives of 2‐deoxy‐1,5‐thioanhydro‐ L ‐hexitol, starting from glycosyl glycals such as D ‐lactal, D ‐cellobial, D ‐maltal, D ‐melibial and D ‐gentiobial, thus avoiding the usually lengthy glycosylation procedures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)