Construction of 4-spiroannulated tetrahydroisoquinoline skeletons via a sequential ring opening of aziridines and Pictet-Spengler reaction

A stepwise cyclization involving a sequential ring opening of aziridines and Pictet-Spengler reaction has been developed for the synthesis of 4-spiroannulated tetrahydroisoquinoline compounds (22 examples). The novel features of this strategy include high bonding efficiency and cyclization efficiency, broad substrate scope, mild conditions and good generality of the ring size in the product.