Organocatalyzed, tandem Michael-lactonizations and a lactamization employing cyclic 1,3-dicarbonyl and an enamino ketone, respectively, were achieved through the intermediacy of α,β-unsaturated acylammonium salts derived from commodity acid chlorides or in situ generated enol esters. 4-Dimethylaminopyridine (DMAP) promotes this process providing the corresponding polycyclic dihydropyranones and a dihydropyridone in good yields. The utility of this methodology was demonstrated in the formal synthesis of the alkaloid dielsine and the anticoagulant warfarin. Comparative 13C NMR studies of acylammonium salt intermediates provide insights into the impact of their formation on the reactivity of the β-carbon.