In situ ball-milling gram-scale preparation of polyoxoniobate-intercalated MgAl-layered double hydroxides for selective aldol and Michael addition cascade reactions

Abstract

The gram-scale preparation of efficient polyoxometalate catalysts is an everlasting yet challenging goal for sustainable organic conversion processes. Herein we report a facile ball-milling strategy to prepare polyoxoniobate-intercalated layered double hydroxide (Mg₃Al-LDH-Nb₆) that shows quite high catalytic activity for the Aldol and Michael addition cascade reactions, e.g. selective synthesis of polysubstituted cyclohexanols and 1,5-diones from arylaldehydes and arylketones. The gram-scale preparation and high reusability with negligible loss of catalytic activity of the Mg₃Al-LDH-Nb₆ catalyst would greatly promote its industrial applications. Additionally, some catalysts exhibit good inhibition effects against human cervix tumor cells (HeLa) and lung cancer human alveolar basal epithelial cells (A549). This work not only develops a facile method for the gram-scale preparation of a new polyoxoniobate-intercalated layered double hydroxide catalyst but also highlights promising biological applications of the catalytic products.