Recent Advances in the Interrupted Nazarov Reaction

In recent decades there have been significant improvements in the efficiency of synthesis as a result of considerable progress in tandem reactions, cascade transformations and related one-pot processes. These methodologies are less time-consuming, more cost-effective, and produce less waste compared to the classical stepwise protocols. The Nazarov cyclization is an important and versatile method for the synthesis of five-membered carbocycles which are found in many natural compounds and functional molecules. Current activities in the field of the Nazarov reaction are focused on development of better catalysts, asymmetric options and increasing the efficiency of synthesis. This transformation is suitable for applying to an intensified step-economy in interrupted versions and one-pot protocols. Interrupted Nazarov reactions in particular take advantage of the stereospecific nature of the electrocyclization. The universality of these reactions has facilitated an access to a plethora of complex small molecules of high medicinal relevance. In this review, we present a comprehensive summary of recent advances in the interrupted Nazarov-type cyclization, and classify these reactions according to the structure of the substrate or the reaction mechanism. This is the first review that presents a survey on various types of interrupted Nazarov cyclization and deals with the recent advances, especially using tandem/domino or one-pot reaction strategies and covers the literature from 2009 to 2019.