13 research outputs found
Reversible CâH activation, facile CâB/BâH metathesis and apparent hydroboration catalysis by a dimethylxantheneâbased frustrated Lewis pair
A dimethylxantheneâbased phosphine/borane frustrated Lewis pair (FLP) is shown to effect reversible Candminus;H activation, cleaving phenylacetylene, PhCCH, to give an equilibrium mixture of the free FLP and phosphonium acetylide in CD2Cl2andnbsp;solution at room temperature. This system also reacts with Bandminus;H bonds although in a different fashion: reactions with HBpin and HBcat proceed via Candminus;B/Bandminus;H metathesis, leading to replacement of the âB(C6F5)2andnbsp;Lewis acid component by âBpin/âBcat, and transfer of HB(C6F5)2andnbsp;to the phosphine Lewis base. This transformation underpins the ability of the FLP to catalyze the hydroboration of alkynes by HBpin: the active species is derived from the HB(C6F5)2fragment generated in this exchange process.</p
Reversible CâH activation, facile CâB/BâH metathesis and apparent hydroboration catalysis by a dimethylxantheneâbased frustrated Lewis pair
A dimethylxantheneâbased phosphine/borane frustrated Lewis pair (FLP) is shown to effect reversible CâH activation, cleaving phenylacetylene, PhCCH, to give an equilibrium mixture of the free FLP and phosphonium acetylide in CD2Cl2Â solution at room temperature. This system also reacts with BâH bonds although in a different fashion: reactions with HBpin and HBcat proceed via CâB/BâH metathesis, leading to replacement of the âB(C6F5)2Â Lewis acid component by âBpin/âBcat, and transfer of HB(C6F5)2Â to the phosphine Lewis base. This transformation underpins the ability of the FLP to catalyze the hydroboration of alkynes by HBpin: the active species is derived from the HB(C6F5)2fragment generated in this exchange process.</p