The asymmetric organocatalytic one-pot synthesis of trans-3,4-disubstituted 3,4-dihydroisoquinolin-1(2H)-ones is described. Starting from 2-(nitromethyl)benzaldehydes and various N-protected aldimines, 5 mol% of a quinine-based squaramide organocatalyst was used to synthesize the title compounds as virtually single diastereomers via an aza-Henry-hemiaminalization-oxidation sequence. Moderate to good yields (39-78%) and moderate to very good enantioselectivities (40-95% ee) were reached.
Keywords: dihydroisoquinolinones; domino reaction; hydrogen bonding; one-pot reaction; organocatalysis.