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)(2)P(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-(OBu)-Bu-t (HT-(OBu)-Bu-t) by the interaction of (KOBu)-Bu-t 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-(OBu)-Bu-t is found to be an efficient solid base for WE reactions for the simple synthesis of alpha, beta-unsaturated esters and nitriles for the first time. The HT-(OBu)-Bu-t, composed of various ratios of Mg/Al (i.e., 2, 2.5, and 3) and different contents of (BuO-)-Bu-t (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. (C) 2003 Elsevier Inc. All rights reserved.