Recent advances in the synthesis of polycyclic and spiro N-heterocycles via aryl alkyne-based strategies

Abstract

Aryl alkynes have emerged as versatile building blocks for the construction of structurally diverse heterocycles owing to their rich reactivity in cascade cyclization processes. Recent advances have enabled the efficient synthesis of fused and spiro N-heterocycles through aryl alkyne-based cascade reactions under photocatalytic, electrochemical, thermal, and transition-metal-catalyzed conditions. These strategies allow rapid assembly of complex molecular architectures with high step economy via simultaneous C–C and C–heteroatom bond formation. This review summarizes recent progress in radical-triggered aryl alkyne cascade cyclization, with emphasis on halogen-, chalcogen-, phosphorus-, and fluoroalkyl-centered radicals, and discusses current challenges and future opportunities in sustainable heterocycle synthesis.