Pictet–Spengler reaction based on in situ generated α-amino iminium ions through the Heyns rearrangement

A useful tandem reaction via the Heyns rearrangement and Pictet–Spengler reaction was developed which ensured the synthesis of complex N-heteropolycycles containing tetrahydro-β-carboline with high yield (up to 96%) and dr (99 : 1). The reaction proceeded smoothly with a catalytic Bronsted acid as a catalyst. The reaction mechanism was investigated which demonstrated that the tandem reaction proceeded due to the in situ produced α-amino iminium ions via the Heyns rearrangement.