Wadsworth–Emmons reaction: the unique catalytic reaction by a solid base

The near-stoichiometric amount of bases is used both in laboratory and industry in Wadsworth–Emmons (WE) reactions, since the by-product, (EtO)2P(O)OH, formed in the reaction neutralizes the base into an inert salt. A strategy to design, develop, and evolve the recyclable Mg–Al–hydrotalcite–O tBu (HT–O tBu) by the interaction of KO tBu with the calcined hydrotalcite that transforms a well-defined stoichiometric WE reaction into a catalytic one in an effort to minimize the quantum of effluents released and reduce the cost of the process is described here. HT–O tBu is found to be an efficient solid base for WE reactions for the simple synthesis of α,β-unsaturated esters and nitriles for the first time. The HT–O tBu, composed of various ratios of Mg/Al (i.e., 2, 2.5, and 3) and different contents of tBuO− (Mg/Al:3), and their precursors were prepared and well characterized to draw a correlation between structure and reactivity of the hydrotalcites in WE reactions.