In recent years, para-quinone methides (p-QMs) have emerged as attractive and versatile synthons in organic synthesis owing to their high reactivity. Consequently, p-QM chemistry has attracted increasing attention and remarkable advances have been achieved. Among the numerous transformations involving p-QMs, catalytic reactions play a pivotal role, and a variety of catalytic systems mediated by Lewis acids, Brønsted acids, bases, transition metals, N-heterocyclic carbenes, and other catalysts have been established for performing 1,6-conjugate addition reactions. Various molecular scaffolds have been constructed using p-QMs to obtain the core structures of numerous natural and synthetic substances of chemical and biomedical relevance. In this review, we provide a comprehensive overview of recent progress in this rapidly growing field by summarizing the 1,6-conjugate addition and annulation reactions of p-QMs with consideration of their mechanisms and applications.

Over the past years, impressive progress has been made on the development of the chemoselective and direct formation of carbon–carbon and carbon–heteroatom bonds involving internal alkynes under catalytic oxidative systems. These transformations heavily rely on the in situ generation of reactive radical intermediates that are initiated by oxidants, visible light photocatalysis, or electrocatalysis and so on. Numerous chemically and biomedically important building blocks have been synthesized, and will continue to be obtained by taking advantage of the radical transformation of internal alkynes in the following years. In this review, we highlight the recent progress in this rapidly growing area by presenting a series of catalytic oxidative reactions, mechanisms and applications which have appeared in the most recent literature.

Catalytic bicyclization of 1,5-enynes anchored by α,β-conjugates with arylsulfonyl radicals was established using TBAI and Cu(OAc)₂as co-catalysts.

A new cascade three-component halosulfonylation of 1,7-enynes for efficient synthesis of densely functionalized 3,4-dihydroquinolin-2(1H)-ones has been established from readily accessible arylsulfonyl hydrazides and NIS (or NBS). The reaction pathway involves in situ-generated sulfonyl radical-triggered α,β-conjugated addition/6-exo-dig cyclization/radical coupling sequence, resulting in continuous multiple bond-forming events including C–S, C–C and C–I (or C–Br) bonds to rapidly build up molecular complexity.