Xanthates reductive desulfurization

Reductive desulfurization has been extended to the appropriate ethyl 1-xanthate or ethyl, phenyl, and naphthyl 1-thioglycosides to prepare the 1,5-anhydro derivatives of D-glucitol, D-mannitol, galactitol, cellobiitol, gentiobiitol, maltitol, lactitol, D-arabitol, ribitol, and xylitol (56). When a 1-thioaldofuranoside is reductively desulfurized, the product is the corresponding 1,4-anhydro alditol (57). 

Thermolysis ° and radical-induced reactions (such as reductionf or termination ) offer a solution and can provide complete desulfurization. Radical-induced reduction of low molecular weight thiocarbonylthio compounds is well known.P Radical-induced reduction of xanthates is the basis of the Barton- McCombie reaction for deoxygenation of secondary alco-hols. ° Stannanes are the most efficient reagents for use in this process but are toxic and residual reagent and the devived reaction bydroducts can be difficult to remove. Hypophosphite salts/ including N-ethylpiperidine hjrpophosphite (17)/ have been recommended as an alternative to stannanes in the radical induced reductions. 

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