Enaminones are gaining increasing interest because of their unique properties and their importance in organic synthesis as versatile building blocks. N,N-Dimethyl enaminones offer a better leaving group (a dimethylamine group) than other enaminones, and allow further elaboration via a range of facile chemical transformations. Over the past five years, there have been an increasing number of reports describing the synthetic applications of N,N-dimethyl enaminones. This review provides a comprehensive overview on the synthetic applications of N,N-dimethyl enaminones that have been reported since 2016. 1 Introduction 2 Direct C(sp²)–H α-Functionalization 2.1 Synthesis of α-Sulfenylated N,N-Dimethyl Enaminones 2.2 Synthesis of α-Thiocyanated N,N-Dimethyl Enaminones 2.3 Synthesis of α-Acyloxylated N,N-Dimethyl Enaminones 3 Functionalization Reactions via C=C Double Bond Cleavage 3.1 Synthesis of Functionalized Methyl Ketones 3.2 Synthesis of α-Ketoamides, α-Ketoesters and 1,2-Diketones 3.3 Synthesis of N-Sulfonyl Amidines 4 Construction of All-Carbon Aromatic Scaffolds 4.1 Synthesis of Benzaldehydes 4.2 Synthesis of the Naphthalenes 5 Construction of Heterocyclic Scaffolds 5.1 Synthesis of Five-Membered Heterocycles 5.2 Synthesis of Six-Membered Heterocycles 5.3 Synthesis of Quinolines 5.4 Synthesis of Functionalized Chromones 5.5 Synthesis of Other Fused Polycyclic Heterocycles 6 Conclusions and Perspectives Received: 20 August 2020 Accepted after revision: 10 September 2020 Publication Date: 03 November 2020 (online) © 2020. Thieme. All rights reserved Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Divergent cascade syntheses constitute a highly attractive and challenging area in synthetic chemistry, and can exhibit unexpected chemoselectivity. Herein, a Brønsted acid-controlled protocol is described for the efficient catalysis of two different reactions, namely acylation cascade- and [1+2+3]-type cyclization of enaminones and isatins for the concise synthesis of highly functionalized pyrrolo[3,4-c]quinolin-1-ones and spirooxindoles in the presence of carboxylic acids and KHSO₄, respectively. The observed chemoselectivity was reasonably explained by trapping the intermediate α,β-unsaturated 2-oxindoles, and the source of the hydroxyl group, carbocation intermediate, and amination reaction were also evaluated.