FREE RADICAL DESULFENYLATION AND DESELENYLATION OF α-SULFUR AND α-SELENO SUBSTITUTED PHOSPHONATES WITH THE<i>n-</i>Bu₃SnH/AIBN REAGENTS SYSTEM¹

Abstract

Abstract Selective desulfenylation and deselenylation of α-sulfur- and α-seleno-substituted phosphonates under free radical conditions are described. Chemoselectivity and scope of the title reactions were studied using phosphonates additionally functionalized in the α-position by alkyl, phenyl, ethoxy, chloro, car-bonyl and sulfenyl groups. It was found that reduction of a halogen tolerates the presence of the sulfenyl group and the latter could be reduced in the presence of the sulfinyl and sulfonyl moieties. Moreover, one sulfenyl group was selectively removed from α-phosphoryl dithioacetals and the phenylsulfenyl group was reduced preferentially in the presence of the methylsulfenyl one.