Ene-iminium intermediates resulting from reaction between glyoxal and β-amino alcohols rearrange by an aza-Cope process. Three different tandem reactions are thus carried out; their first component is this cationic rearrangement, the second step being either an iminium hydrolysis, a nucleophile-induced ene-iminium cyclization or a Mannich reaction. The last two sequences lead to homochiral proline