Reduction of heterocyclic carboxaldehydes via Meerwein–Ponndorf–Verley reaction

A series of Mg/Al and Mg/Al/Zr layered double hydroxides (LDHs) was prepared for use as catalysts in the Meerwein–Ponndorf–Verley (MPV) reaction of heterocyclic carboxaldehydes. Analysis of the solids revealed that zirconium is in fact incorporated into the LDH structure; as a result, their calcination produces Mg/Al/Zr oxides that are effective catalysts for the MPV reduction of heterocyclic compounds. In fact, the catalysts thus obtained exhibited higher activity than a catalyst obtained from an LDH containing Mg and Al only. The reaction was conducted under very mild conditions (viz. atmospheric pressure and a temperature of 82 °C) and provided conversions close to 90 and 100% selectivity in all instances.