Zinc Catalyzed Hydroboration of Esters and Nitriles with Pinacolborane

Abstract

We developed a bench-stable iminopyridine-ligated zinc complex for the effective catalytic hydroboration of esters and nitriles under solvent-free conditions. Various esters and nitriles bearing different functionalities were selectively reduced to form corresponding alcohols and amines in good yields. Detailed Hammett plots are provided to explain the electronic effects on the phenyl ring.

Zinc hydride catalyzed hydroboration of esters

“…H ). 13 Authors also utilized commercially available zinc salts as catalysts. However, Schiff base stabilized zinc diiodide acts as a superior catalyst.…”

Magnesium(ii) complexes supported by indole- and pyrrole-containing Schiff-base ligands: syntheses, structures, and applications as precatalysts in the hydroboration of nitriles and alkynes

“…30,31 Since Nikonov and coworkers discovered that a Mo(IV) complex could catalyse the hydroboration of nitriles in 2012, 32,33 research on the hydroboration of nitriles or alkynes has been increasing. A plethora of transition-metal complexes, such as zirconium, 34 manganese, 35 iron, 36,37 cobalt, 22,[38][39][40][41][42][43] nickel, [44][45][46] zinc, [47][48][49][50][51][52][53] ruthenium, [54][55][56] palladium, 57 and many rare-earth metal complexes, [58][59][60] can catalyse the hydroboration of nitriles or alkynes. In recent years, earth-abundant, nontoxic and inexpensive main group-metal compounds have become favourable catalysts in these research fields.…”

Tri-coordinated zinc alkyl complexes with N^S/Se coordination of imino-phosphanamidinate chalcogenide ligands as precursors for efficient hydroboration of nitriles and esters

“…Recently zinc complexes have also started to gain the attention of researchers as potential catalysts for hydroboration reactions. 33–39 Yao et al and Mukherjee et al independently reported multidentate phenolate ligand-supported zinc alkyl complexes and N -heterocyclic carbine-based zinc complexes as catalysts for regioselective hydroboration of N -heteroarenes. 40,41 The Nembenna group established a conjugated bis-guanidinate zinc hydride complex as a catalyst for the hydroboration of isonitriles, nitriles and esters.…”