Abstract Previously unexplored enantiopure zwitterionic ammonium dienolates have been utilized in this work as reactive intermediates that act as diene components in hetero-Diels– Alder reactions (HDAs) with aldehydes to produce optically active δ-lactones, subunits of numerous bioactive products. The dienolates were generated in situ from E/Z mixtures of α, β-unsaturated acid chlorides by use of a nucleophilic quinidine derivative and Sn (OTf) 2 ...
