6.1 Thiol–Ene/Yne Click Reactions: A Powerful Tool Toward Diversity-Oriented Synthesis

The clickable addition reaction between thiols and unsaturated compounds leading to the generation of (branched/linear) thioethers or (branched/linear) vinyl sulfides is known as the hydrothiolation reaction. Based upon the nature of unsaturation, i.e. double bond or triple bond, hydrothiolation reactions are classified as thiol–ene and thiol–yne click reactions, respectively. These reactions have emerged as a powerful and widely used strategy for the generation of carbon–sulfur bonds due to several associated benefits including versatile synthetic procedures, wide functional-group tolerance, high atom economy with few to no byproducts, and simple purification. The hydrothiolation reactions have numerous trapping applications in the fields of polymer chemistry, nanoengineering, pharmaceuticals, natural products, and perhaps most importantly in medicinal chemistry for the synthesis of many drugs and bioactive molecules.

Diversity-Oriented Synthesis: Amino Acetophenones as Building Blocks for the Synthesis of Natural Product Analogs

Diversity-Oriented Synthesis (DOS) represents a strategy to obtain molecule libraries with diverse structural features starting from one common compound in limited steps of synthesis. During the last two decades, DOS has become an unmissable strategy in organic synthesis and is fully integrated in various drug discovery processes. On the other hand, natural products with multiple relevant pharmacological properties have been extensively investigated as scaffolds for ligand-based drug design. In this article, we report the amino dimethoxyacetophenones that can be easily synthesized and scaled up from the commercially available 3,5-dimethoxyaniline as valuable starting blocks for the DOS of natural product analogs. More focus is placed on the synthesis of analogs of flavones, coumarins, azocanes, chalcones, and aurones, which are frequently studied as lead compounds in drug discovery.

The Pseudo-Symmetric N-benzyl Hydroxyethylamine Core in a New Series of Heteroarylcarboxyamide HIV-1 Pr Inhibitors: Synthesis, Molecular Modeling and Biological Evaluation

New series of compounds containing both heterocycle moieties and pseudo-symmetric hydroxyethylamine core were obtained using a simple synthetic path that can provide a library of compounds in few steps and high yields. Furthermore, diversity-oriented synthesis was studied to change different functionalities according to needs. The in vitro inhibition activity against recombinant HIV-1 protease was evaluated. A beneficial effect of this class of compounds can be obtained either for the presence of a bis-benzyl group into the core and for the heterocyclic moiety in P1, specifically the indole ring. Docking analysis was also reported.

Enantioselective Palladium-Catalyzed Decarboxylative Dearomative Asymmetric Allylic Alkylation of Benzofurans: Diversity-Oriented Synthesis of Flavaglines

With the introduction of new Trost-type bisphosphine ligands bearing a chiral cycloalkane framework, the highly efficient and enantioselective Palladium-catalyzed decarboxylative dearomative asymmetric allylic alkylation (AAA) of benzofurans was achieved. This enabled a diversity-oriented synthesis (DOS) of previously unreachable flavaglines, which features two diversification stages. A new avenue for developing flavagline-based drugs was thus established.