Intramolecular Pictet–Spengler Reaction of Cyclic Iminium ions: A Novel Access to Benzo[1,4]oxazepine‐Fused Tetrahydroisoquinoline and Tetrahydro‐β‐carboline Analogues

Abstract

AbstractA simple and efficient approach has been developed for the synthesis of benzo[1,4]oxazepino‐fused tetrahydroisoquinoline and tetrahydro‐β‐carboline derivatives via one‐pot cascade reaction sequence. This reaction involves the intramolecular Pictet–Spengler reaction of cyclic iminium ions, which were generated in situ via trifluoroacetic acid (TFA)‐mediated deprotection of an acetal derived from β‐arylethylamines and 2‐(2,2‐diethoxyethoxy)benzaldehyde. All reactions produced a novel library of complex fused polyheterocyclic compounds in good to excellent yields.