Addition of Sulfur Based Electrophiles to Glycals

Addition of PhSCl to the bottom face of the //s (d) conformer of D-glucal 69 leads to the episulfonium ion 71 and should be favored relative to the top face addition leading to 70, owing to non-bonded interactions of the PhS- unit with the adjacent TBS ether in the latter case. This diastereofacial selectivity, however, 

Desulfurization is achieved with Raney-nickel in refluxing ethanol or tetrahy-drofuran at room temperature [46], or BusSnH-AIBN in toluene at 100°C [49], 

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