An (E)-selective synthesis of trisubstituted (E)-(alpha),(beta)-unsaturated acid derivatives

Potassium alkoxides of N-acyloxazolidin-2-one derived syn-aldolates undergo a novel tandem intramolecular cyclisation elimination reaction to afford trisubstituted (E)-(alpha),(beta)-unsaturated amides in high d.e., which may be converted into their corresponding acids or oxazolines in good yield.