Radical Reactions of Carbohydrates

Volume II: Radical Reactions in Carbohydrate Synthesis

Appendix I: Hydrogen-Atom Donors

Appendix I is in a portable document file (pdf) and can be viewed by clicking the blue, Appendix I button below. The drawing underneath the button pictures the formation and reaction of a carbohydrate radical produced from a halogenated carbohydrate. Beside the drawing is a description of the reaction. Below the drawing and its description is a summary of Appendix I.

Appendix I: Hydrogen-Atom Donors

This drawing shows a reaction for regenerating tri-n-butyltin hydride.

Drawing Description

Polymethylhydrosiloxane [PMHS, (MeSiHO)n] in the presence of potassium fluoride reacts with tri-n-butyltin halides to produce Bu3SnH (eq 3 in Appendix I). This regeneration of tri-n-butyltin hydride dramatically reduces the amount of tin-containing material needed for radical reaction of carbohydrate halides.

Summary of Appendix I

Since some tin-containing compounds are toxic and can cause puri­fi­cation problems, pro­cedures have been developed both to minimize the amount of these materials needed for successful reaction and to make their removal easier and more complete. Another solution to toxicity and purification problems created by tin-containing compounds is to replace them with less offensive reagents. An effective replacement is tris(trimethylsilyl)silane. For reactive carbohydrate iodides cyclohexane also can be used.