Metal-doped mesoporous ZrO2 catalyzed chemoselective synthesis of allylic alcohols from Meerwein–Ponndorf–Verley reduction of α,β-unsaturated aldehydes

Abstract

Meerwein–Ponndorf–Verley reduction (MPVr) is a sustainable route for the chemoselective transformation of α,β-unsaturated aldehydes. However, tailoring ZrO₂ catalysts for improved surface-active sites and maximum performance in the MPV reaction is still a challenge. Here, we synthesized mesoporous zirconia (ZrO₂) and metal-doped zirconia (M_ZrO₂, M = Cr, Mn, Fe, and Ni). The incorporation of metal dopants into zirconia's crystal framework alters its physico-chemical properties such as surface area and total acidity-basicity. The prepared catalysts were evaluated in the MPVr using 2-propanol as a hydrogen donor under mild reaction conditions. The catalysts' remarkable reactivity depends mainly on their surface mesostructure's intrinsic properties rather than the specific surface area. Cr_ZrO₂, which is stable and sustainable, presented superior activity and 100% selectivity to unsaturated alcohols. The synergistic effect between Cr and Zr species in the binary oxide facilitated the Lewis acidity-induced performance of the Cr_ZrO₂ catalyst. Our work presents the first innovative application of a well-designed mesoporous Cr_ZrO₂ in the green synthesis of unsaturated alcohols with exceptional reactivity.