Toward selective functionalisation of oligosilanes: borane-catalysed dehydrogenative coupling of silanes with thiols

Among established methods for transforming Si-H bonds, carbonyl hydrosilylation and heterodehydrogenative coupling with alcohols catalysed by B(C(6)F(5))(3) are shown to provide exceptionally clean routes to the derivatisation of tetra-substituted disilanes such as [Ph(2)SiII](2), giving no products resulting from Si-Si bond cleavage. Even higher activity is observed for the borane-catalysed dehydrogenative coupling of silanes with alkyl-and arylthiols, the first examples of such Si-S bond formation in the absence of a transition metal catalyst. Clean, quantitative syntheses of a range of thiosilanes are reported, and the lability of the Si-S linkage toward subsequent alcoholysis is investigated. The crystal structure of 2,3-disila-2,2,3,3-tetramethyl-1,4-benzodioxane is presented.