Multicomponent domino reactions (MDRs) serve as a rapid and efficient tool for the synthesis of versatile heterocycles, particularly those containing structural diversity and complexity, by a one-pot operation. These reactions can dramatically reduce the generation of chemical wastes, costs of starting materials, and the use of energy and manpower. Moreover, the reaction period can be substantially shortened. This Review covers recent advances on multicomponent domino reactions for the construction of five-, six-, and seven-membered heterocyclic skeletons and their multicyclic derivatives.

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.

A metal‐free [2+2] cycloaddition and 1,4‐addition sequence induced by S‐centered radicals has been achieved by treating benzene‐linked allene‐ynes with aryldiazonium tetrafluoroborates and DABCO‐bis(sulfur dioxide) in a one‐pot procedure. The reaction provides a greener and more practical access to functionalized cyclobuta[a]naphthalen‐4‐ols with valuable applications. More than 50 examples are demonstrated with excellent diastereoselectivity and chemical yields. The reaction pathway is proposed to proceed by the following steps:[2+2] cycloaddition, insertion of SO2, 1,4‐addition, diazotization, and tautomerization.

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.

A novel application of highly stable Fe(OTf) 3 as an efficient catalyst for carbon-carbon bond formation via the activation of a terminal alkyne C-H bond under solvent-free conditions is described. Notably, this protocol of green synthesis, which produced quinolines from the reaction of amines, aldehydes and terminal aryl alkynes, shows attractive characteristics including concise onepot conditions, high atom economy, very limited energy consumption, and the sequential catalytic process requires only a catalytic (5 mol%) amount of Fe(OTf) 3 with short reaction periods (3 h). Meanwhile, the catalyst was easily recovered from the reaction system and reused smoothly with only a little loss of activity.