Pictet-Spengler reactions for the synthesis of pharmaceutically relevant heterocycles.

The synthesis of biologically active heterocyclic scaffolds is one of the significant challenges of modern synthetic chemistry. The Pictet-Spengler (PS) reaction, known for approximately a century, remains a particularly popular cyclization method. This review describes recent applications of the PS reaction in the total synthesis of alkaloids and biologically active analogs of tetrahydroisoquinoline and tetrahydro-β-carboline. The utility of PS cyclization in the synthesis of a range of heterocyclic scaffolds is also described.