Selective ligand-free cobalt-catalysed reduction of esters to aldehydes or alcohols

Cobalt(II) salts combined with NaBHEt3 and eventually a base catalyse efficiently and selectively the reduction of esters to aldehydes or alcohols through hydrosilylation by using phenylsilane. Catalyst characterisation by XRD, XPS, TEM and STEM analyses indicates the materials were partially crystalline with the presence of cobalt nanoparticles. Control experiments suggested low valent Co(0) was the active catalytic species involved.