In this paper, we described the preparation of fused (Het)Aryltetrahydroindolizinones via N-acyl iminium intermediates. Two different routes were also explored to achieve the synthesis. The first one consists in the intramolecular reaction of β-hydroxylactams whereas the second route one is an intermolecular condensation between a 2-formylester or a β-alkoxylactone and an appropriate primary amine