The Pictet–Spengler Reaction: A Powerful Strategy for the Synthesis of Heterocycles

Ever since Amé Pictet and Theodor Spengler discovered their way to synthesize tetrahydroisoquinolines and β-carbolines, their method became a powerful methodology for the preparation of many natural products and pharmaceuticals. This method involves the reaction of arylethanamines and a carbonyl compound, such as aldehydes or ketones, under acidic medium. Trifluoroacetic acid and boron trifluoride etherate (BF3 ⋅ Et2O) are the common acidic catalysts employed in this reaction, although, sometimes organocatalysts and the chiral organophosphoric acids may catalyzed this reaction. In this chapter, the development of the Pictet–Spengler reaction is illustrated by the synthesis of various types of heterocyclic compounds.