A Rapid Synthesis of 2,3,11,11a-Tetrahydro-6H-pyrazino[1,2-b]isoquinoline-1,4-diones Through an Amido Iminium Ion Cyclization

Abstract

7,10-Dimethoxy-6-methyl-2,3,11,11a-tetrahydro-6H-pyrazino[1,2-b]isoquinoline-1,4-diones (5) and (6) were synthesized from glycine anhydride and 2,5-dimethoxybenzaldehyde through an amido iminium ion cyclization reaction. This method for the construction of the tetrahydroisoquinoline ring will be useful for the synthesis of saframycins.