Ring Fused Cyclic Aminals from Tetrahydro-β-Carboline-based Dipeptide Compounds

An acid- and oxidant-promoted intramolecular cyclization of a tetrahydro-β-carboline-based dipeptide has been developed to prepare new indole-fused aminoacetales. This approach involves N-acyliminium formation from readily available precursors, and cyclization in mild reaction conditions. The diastereoselectivity in the formation of the products is influenced by the specific substituents of the starting reagents, which has been rationalized analyzing the energy profile of the related reactions and the relative stability of the proposed structures based on DFT computational methods.