Reductive Removal of Sulfonyl Groups : Cleavage of Sulfonamides and Sulfonates by Alkali Metal combined with Crown Ether

Abstract

A system of potassium metal-crown ether-diglyme has been proved to be highly effective for reductive removal of the sulfonyl group from O-sulfonates or sulfonamides. The reaction proceeds even with mesylamides of dialkyl amines, which resist reductive cleavage by naphthalene radical anion. It has also been found that a simple combination of potassium metal or sodium-potassium alloy with isopropanol in diglyme or toluene is effective for the cleavage of dialkylamine sulfonamides which are relatively susceptible to reduction. In particular, the use of sodium-potassium alloy gave satisfactory results.