Solvent-free Zn (NSNO) complex-catalysed dihydroboration of nitriles

Abstract

N-donors are the most commonly employed Lewis bases in ligand-assisted catalysis. A dimeric zinc complex (Zn-1) employing a tetradentate pyridine-thioether-anilido-aryloxide NSNO ligand (L) effects the quantitative conversion of nitriles to the corresponding double hydroborated products at 1 mol% catalyst loading. Variable Time Normalization Analysis kinetic studies showed a first-order dependence with respect to the nitrile, pinacolborane and zinc and clear evidence for catalyst deactivation. A plausible ligand-assisted reaction pathway involves B–H bond activation by the aryloxide (vs. anilido) donor.